1 /*
   2  * Copyright (c) 2000, 2023, 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, nullptr) {
  61   assert(arena != nullptr, "invariant");
  62 }
  63 
  64 // Allocate growable array storage in current ResourceArea.
  65 ciTypeFlow::JsrSet::JsrSet(int default_len) : _set(default_len, 0, nullptr) {}
  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 = nullptr;
 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 nullptr;
 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 == nullptr) {
 376       record_failure("cannot reach OSR point");
 377       return nullptr;
 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 == nullptr) {
 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 = nullptr;
 652   ciMethod* callee = str->get_method(will_link, &declared_signature);
 653   assert(declared_signature != nullptr, "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, nullptr,
 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   if (str->is_in_error()) {
 724     trap(str, nullptr, Deoptimization::make_trap_request(Deoptimization::Reason_unhandled,
 725                                                       Deoptimization::Action_none));
 726     return;
 727   }
 728   ciConstant con = str->get_constant();
 729   if (con.is_valid()) {
 730     int cp_index = str->get_constant_pool_index();
 731     BasicType basic_type = str->get_basic_type_for_constant_at(cp_index);
 732     if (is_reference_type(basic_type)) {
 733       ciObject* obj = con.as_object();
 734       if (obj->is_null_object()) {
 735         push_null();
 736       } else {
 737         assert(obj->is_instance() || obj->is_array(), "must be java_mirror of klass");
 738         push_object(obj->klass());
 739       }
 740     } else {
 741       assert(basic_type == con.basic_type() || con.basic_type() == T_OBJECT,
 742              "not a boxed form: %s vs %s", type2name(basic_type), type2name(con.basic_type()));
 743       push_translate(ciType::make(basic_type));
 744     }
 745   } else {
 746     // OutOfMemoryError in the CI while loading a String constant.
 747     push_null();
 748     outer()->record_failure("ldc did not link");
 749   }
 750 }
 751 
 752 // ------------------------------------------------------------------
 753 // ciTypeFlow::StateVector::do_multianewarray
 754 void ciTypeFlow::StateVector::do_multianewarray(ciBytecodeStream* str) {
 755   int dimensions = str->get_dimensions();
 756   bool will_link;
 757   ciArrayKlass* array_klass = str->get_klass(will_link)->as_array_klass();
 758   if (!will_link) {
 759     trap(str, array_klass, str->get_klass_index());
 760   } else {
 761     for (int i = 0; i < dimensions; i++) {
 762       pop_int();
 763     }
 764     push_object(array_klass);
 765   }
 766 }
 767 
 768 // ------------------------------------------------------------------
 769 // ciTypeFlow::StateVector::do_new
 770 void ciTypeFlow::StateVector::do_new(ciBytecodeStream* str) {
 771   bool will_link;
 772   ciKlass* klass = str->get_klass(will_link);
 773   if (!will_link || str->is_unresolved_klass()) {
 774     trap(str, klass, str->get_klass_index());
 775   } else {
 776     push_object(klass);
 777   }
 778 }
 779 
 780 // ------------------------------------------------------------------
 781 // ciTypeFlow::StateVector::do_newarray
 782 void ciTypeFlow::StateVector::do_newarray(ciBytecodeStream* str) {
 783   pop_int();
 784   ciKlass* klass = ciTypeArrayKlass::make((BasicType)str->get_index());
 785   push_object(klass);
 786 }
 787 
 788 // ------------------------------------------------------------------
 789 // ciTypeFlow::StateVector::do_putfield
 790 void ciTypeFlow::StateVector::do_putfield(ciBytecodeStream* str) {
 791   do_putstatic(str);
 792   if (_trap_bci != -1)  return;  // unloaded field holder, etc.
 793   // could add assert here for type of object.
 794   pop_object();
 795 }
 796 
 797 // ------------------------------------------------------------------
 798 // ciTypeFlow::StateVector::do_putstatic
 799 void ciTypeFlow::StateVector::do_putstatic(ciBytecodeStream* str) {
 800   bool will_link;
 801   ciField* field = str->get_field(will_link);
 802   if (!will_link) {
 803     trap(str, field->holder(), str->get_field_holder_index());
 804   } else {
 805     ciType* field_type = field->type();
 806     ciType* type = pop_value();
 807     // Do I want to check this type?
 808     //      assert(type->is_subtype_of(field_type), "bad type for field value");
 809     if (field_type->is_two_word()) {
 810       ciType* type2 = pop_value();
 811       assert(type2->is_two_word(), "must be 2nd half");
 812       assert(type == half_type(type2), "must be 2nd half");
 813     }
 814   }
 815 }
 816 
 817 // ------------------------------------------------------------------
 818 // ciTypeFlow::StateVector::do_ret
 819 void ciTypeFlow::StateVector::do_ret(ciBytecodeStream* str) {
 820   Cell index = local(str->get_index());
 821 
 822   ciType* address = type_at(index);
 823   assert(address->is_return_address(), "bad return address");
 824   set_type_at(index, bottom_type());
 825 }
 826 
 827 // ------------------------------------------------------------------
 828 // ciTypeFlow::StateVector::trap
 829 //
 830 // Stop interpretation of this path with a trap.
 831 void ciTypeFlow::StateVector::trap(ciBytecodeStream* str, ciKlass* klass, int index) {
 832   _trap_bci = str->cur_bci();
 833   _trap_index = index;
 834 
 835   // Log information about this trap:
 836   CompileLog* log = outer()->env()->log();
 837   if (log != nullptr) {
 838     int mid = log->identify(outer()->method());
 839     int kid = (klass == nullptr)? -1: log->identify(klass);
 840     log->begin_elem("uncommon_trap method='%d' bci='%d'", mid, str->cur_bci());
 841     char buf[100];
 842     log->print(" %s", Deoptimization::format_trap_request(buf, sizeof(buf),
 843                                                           index));
 844     if (kid >= 0)
 845       log->print(" klass='%d'", kid);
 846     log->end_elem();
 847   }
 848 }
 849 
 850 // ------------------------------------------------------------------
 851 // ciTypeFlow::StateVector::do_null_assert
 852 // Corresponds to graphKit::do_null_assert.
 853 void ciTypeFlow::StateVector::do_null_assert(ciKlass* unloaded_klass) {
 854   if (unloaded_klass->is_loaded()) {
 855     // We failed to link, but we can still compute with this class,
 856     // since it is loaded somewhere.  The compiler will uncommon_trap
 857     // if the object is not null, but the typeflow pass can not assume
 858     // that the object will be null, otherwise it may incorrectly tell
 859     // the parser that an object is known to be null. 4761344, 4807707
 860     push_object(unloaded_klass);
 861   } else {
 862     // The class is not loaded anywhere.  It is safe to model the
 863     // null in the typestates, because we can compile in a null check
 864     // which will deoptimize us if someone manages to load the
 865     // class later.
 866     push_null();
 867   }
 868 }
 869 
 870 
 871 // ------------------------------------------------------------------
 872 // ciTypeFlow::StateVector::apply_one_bytecode
 873 //
 874 // Apply the effect of one bytecode to this StateVector
 875 bool ciTypeFlow::StateVector::apply_one_bytecode(ciBytecodeStream* str) {
 876   _trap_bci = -1;
 877   _trap_index = 0;
 878 
 879   if (CITraceTypeFlow) {
 880     tty->print_cr(">> Interpreting bytecode %d:%s", str->cur_bci(),
 881                   Bytecodes::name(str->cur_bc()));
 882   }
 883 
 884   switch(str->cur_bc()) {
 885   case Bytecodes::_aaload: do_aaload(str);                       break;
 886 
 887   case Bytecodes::_aastore:
 888     {
 889       pop_object();
 890       pop_int();
 891       pop_objArray();
 892       break;
 893     }
 894   case Bytecodes::_aconst_null:
 895     {
 896       push_null();
 897       break;
 898     }
 899   case Bytecodes::_aload:   load_local_object(str->get_index());    break;
 900   case Bytecodes::_aload_0: load_local_object(0);                   break;
 901   case Bytecodes::_aload_1: load_local_object(1);                   break;
 902   case Bytecodes::_aload_2: load_local_object(2);                   break;
 903   case Bytecodes::_aload_3: load_local_object(3);                   break;
 904 
 905   case Bytecodes::_anewarray:
 906     {
 907       pop_int();
 908       bool will_link;
 909       ciKlass* element_klass = str->get_klass(will_link);
 910       if (!will_link) {
 911         trap(str, element_klass, str->get_klass_index());
 912       } else {
 913         push_object(ciObjArrayKlass::make(element_klass));
 914       }
 915       break;
 916     }
 917   case Bytecodes::_areturn:
 918   case Bytecodes::_ifnonnull:
 919   case Bytecodes::_ifnull:
 920     {
 921       pop_object();
 922       break;
 923     }
 924   case Bytecodes::_monitorenter:
 925     {
 926       pop_object();
 927       set_monitor_count(monitor_count() + 1);
 928       break;
 929     }
 930   case Bytecodes::_monitorexit:
 931     {
 932       pop_object();
 933       assert(monitor_count() > 0, "must be a monitor to exit from");
 934       set_monitor_count(monitor_count() - 1);
 935       break;
 936     }
 937   case Bytecodes::_arraylength:
 938     {
 939       pop_array();
 940       push_int();
 941       break;
 942     }
 943   case Bytecodes::_astore:   store_local_object(str->get_index());  break;
 944   case Bytecodes::_astore_0: store_local_object(0);                 break;
 945   case Bytecodes::_astore_1: store_local_object(1);                 break;
 946   case Bytecodes::_astore_2: store_local_object(2);                 break;
 947   case Bytecodes::_astore_3: store_local_object(3);                 break;
 948 
 949   case Bytecodes::_athrow:
 950     {
 951       NEEDS_CLEANUP;
 952       pop_object();
 953       break;
 954     }
 955   case Bytecodes::_baload:
 956   case Bytecodes::_caload:
 957   case Bytecodes::_iaload:
 958   case Bytecodes::_saload:
 959     {
 960       pop_int();
 961       ciTypeArrayKlass* array_klass = pop_typeArray();
 962       // Put assert here for right type?
 963       push_int();
 964       break;
 965     }
 966   case Bytecodes::_bastore:
 967   case Bytecodes::_castore:
 968   case Bytecodes::_iastore:
 969   case Bytecodes::_sastore:
 970     {
 971       pop_int();
 972       pop_int();
 973       pop_typeArray();
 974       // assert here?
 975       break;
 976     }
 977   case Bytecodes::_bipush:
 978   case Bytecodes::_iconst_m1:
 979   case Bytecodes::_iconst_0:
 980   case Bytecodes::_iconst_1:
 981   case Bytecodes::_iconst_2:
 982   case Bytecodes::_iconst_3:
 983   case Bytecodes::_iconst_4:
 984   case Bytecodes::_iconst_5:
 985   case Bytecodes::_sipush:
 986     {
 987       push_int();
 988       break;
 989     }
 990   case Bytecodes::_checkcast: do_checkcast(str);                  break;
 991 
 992   case Bytecodes::_d2f:
 993     {
 994       pop_double();
 995       push_float();
 996       break;
 997     }
 998   case Bytecodes::_d2i:
 999     {
1000       pop_double();
1001       push_int();
1002       break;
1003     }
1004   case Bytecodes::_d2l:
1005     {
1006       pop_double();
1007       push_long();
1008       break;
1009     }
1010   case Bytecodes::_dadd:
1011   case Bytecodes::_ddiv:
1012   case Bytecodes::_dmul:
1013   case Bytecodes::_drem:
1014   case Bytecodes::_dsub:
1015     {
1016       pop_double();
1017       pop_double();
1018       push_double();
1019       break;
1020     }
1021   case Bytecodes::_daload:
1022     {
1023       pop_int();
1024       ciTypeArrayKlass* array_klass = pop_typeArray();
1025       // Put assert here for right type?
1026       push_double();
1027       break;
1028     }
1029   case Bytecodes::_dastore:
1030     {
1031       pop_double();
1032       pop_int();
1033       pop_typeArray();
1034       // assert here?
1035       break;
1036     }
1037   case Bytecodes::_dcmpg:
1038   case Bytecodes::_dcmpl:
1039     {
1040       pop_double();
1041       pop_double();
1042       push_int();
1043       break;
1044     }
1045   case Bytecodes::_dconst_0:
1046   case Bytecodes::_dconst_1:
1047     {
1048       push_double();
1049       break;
1050     }
1051   case Bytecodes::_dload:   load_local_double(str->get_index());    break;
1052   case Bytecodes::_dload_0: load_local_double(0);                   break;
1053   case Bytecodes::_dload_1: load_local_double(1);                   break;
1054   case Bytecodes::_dload_2: load_local_double(2);                   break;
1055   case Bytecodes::_dload_3: load_local_double(3);                   break;
1056 
1057   case Bytecodes::_dneg:
1058     {
1059       pop_double();
1060       push_double();
1061       break;
1062     }
1063   case Bytecodes::_dreturn:
1064     {
1065       pop_double();
1066       break;
1067     }
1068   case Bytecodes::_dstore:   store_local_double(str->get_index());  break;
1069   case Bytecodes::_dstore_0: store_local_double(0);                 break;
1070   case Bytecodes::_dstore_1: store_local_double(1);                 break;
1071   case Bytecodes::_dstore_2: store_local_double(2);                 break;
1072   case Bytecodes::_dstore_3: store_local_double(3);                 break;
1073 
1074   case Bytecodes::_dup:
1075     {
1076       push(type_at_tos());
1077       break;
1078     }
1079   case Bytecodes::_dup_x1:
1080     {
1081       ciType* value1 = pop_value();
1082       ciType* value2 = pop_value();
1083       push(value1);
1084       push(value2);
1085       push(value1);
1086       break;
1087     }
1088   case Bytecodes::_dup_x2:
1089     {
1090       ciType* value1 = pop_value();
1091       ciType* value2 = pop_value();
1092       ciType* value3 = pop_value();
1093       push(value1);
1094       push(value3);
1095       push(value2);
1096       push(value1);
1097       break;
1098     }
1099   case Bytecodes::_dup2:
1100     {
1101       ciType* value1 = pop_value();
1102       ciType* value2 = pop_value();
1103       push(value2);
1104       push(value1);
1105       push(value2);
1106       push(value1);
1107       break;
1108     }
1109   case Bytecodes::_dup2_x1:
1110     {
1111       ciType* value1 = pop_value();
1112       ciType* value2 = pop_value();
1113       ciType* value3 = pop_value();
1114       push(value2);
1115       push(value1);
1116       push(value3);
1117       push(value2);
1118       push(value1);
1119       break;
1120     }
1121   case Bytecodes::_dup2_x2:
1122     {
1123       ciType* value1 = pop_value();
1124       ciType* value2 = pop_value();
1125       ciType* value3 = pop_value();
1126       ciType* value4 = pop_value();
1127       push(value2);
1128       push(value1);
1129       push(value4);
1130       push(value3);
1131       push(value2);
1132       push(value1);
1133       break;
1134     }
1135   case Bytecodes::_f2d:
1136     {
1137       pop_float();
1138       push_double();
1139       break;
1140     }
1141   case Bytecodes::_f2i:
1142     {
1143       pop_float();
1144       push_int();
1145       break;
1146     }
1147   case Bytecodes::_f2l:
1148     {
1149       pop_float();
1150       push_long();
1151       break;
1152     }
1153   case Bytecodes::_fadd:
1154   case Bytecodes::_fdiv:
1155   case Bytecodes::_fmul:
1156   case Bytecodes::_frem:
1157   case Bytecodes::_fsub:
1158     {
1159       pop_float();
1160       pop_float();
1161       push_float();
1162       break;
1163     }
1164   case Bytecodes::_faload:
1165     {
1166       pop_int();
1167       ciTypeArrayKlass* array_klass = pop_typeArray();
1168       // Put assert here.
1169       push_float();
1170       break;
1171     }
1172   case Bytecodes::_fastore:
1173     {
1174       pop_float();
1175       pop_int();
1176       ciTypeArrayKlass* array_klass = pop_typeArray();
1177       // Put assert here.
1178       break;
1179     }
1180   case Bytecodes::_fcmpg:
1181   case Bytecodes::_fcmpl:
1182     {
1183       pop_float();
1184       pop_float();
1185       push_int();
1186       break;
1187     }
1188   case Bytecodes::_fconst_0:
1189   case Bytecodes::_fconst_1:
1190   case Bytecodes::_fconst_2:
1191     {
1192       push_float();
1193       break;
1194     }
1195   case Bytecodes::_fload:   load_local_float(str->get_index());     break;
1196   case Bytecodes::_fload_0: load_local_float(0);                    break;
1197   case Bytecodes::_fload_1: load_local_float(1);                    break;
1198   case Bytecodes::_fload_2: load_local_float(2);                    break;
1199   case Bytecodes::_fload_3: load_local_float(3);                    break;
1200 
1201   case Bytecodes::_fneg:
1202     {
1203       pop_float();
1204       push_float();
1205       break;
1206     }
1207   case Bytecodes::_freturn:
1208     {
1209       pop_float();
1210       break;
1211     }
1212   case Bytecodes::_fstore:    store_local_float(str->get_index());   break;
1213   case Bytecodes::_fstore_0:  store_local_float(0);                  break;
1214   case Bytecodes::_fstore_1:  store_local_float(1);                  break;
1215   case Bytecodes::_fstore_2:  store_local_float(2);                  break;
1216   case Bytecodes::_fstore_3:  store_local_float(3);                  break;
1217 
1218   case Bytecodes::_getfield:  do_getfield(str);                      break;
1219   case Bytecodes::_getstatic: do_getstatic(str);                     break;
1220 
1221   case Bytecodes::_goto:
1222   case Bytecodes::_goto_w:
1223   case Bytecodes::_nop:
1224   case Bytecodes::_return:
1225     {
1226       // do nothing.
1227       break;
1228     }
1229   case Bytecodes::_i2b:
1230   case Bytecodes::_i2c:
1231   case Bytecodes::_i2s:
1232   case Bytecodes::_ineg:
1233     {
1234       pop_int();
1235       push_int();
1236       break;
1237     }
1238   case Bytecodes::_i2d:
1239     {
1240       pop_int();
1241       push_double();
1242       break;
1243     }
1244   case Bytecodes::_i2f:
1245     {
1246       pop_int();
1247       push_float();
1248       break;
1249     }
1250   case Bytecodes::_i2l:
1251     {
1252       pop_int();
1253       push_long();
1254       break;
1255     }
1256   case Bytecodes::_iadd:
1257   case Bytecodes::_iand:
1258   case Bytecodes::_idiv:
1259   case Bytecodes::_imul:
1260   case Bytecodes::_ior:
1261   case Bytecodes::_irem:
1262   case Bytecodes::_ishl:
1263   case Bytecodes::_ishr:
1264   case Bytecodes::_isub:
1265   case Bytecodes::_iushr:
1266   case Bytecodes::_ixor:
1267     {
1268       pop_int();
1269       pop_int();
1270       push_int();
1271       break;
1272     }
1273   case Bytecodes::_if_acmpeq:
1274   case Bytecodes::_if_acmpne:
1275     {
1276       pop_object();
1277       pop_object();
1278       break;
1279     }
1280   case Bytecodes::_if_icmpeq:
1281   case Bytecodes::_if_icmpge:
1282   case Bytecodes::_if_icmpgt:
1283   case Bytecodes::_if_icmple:
1284   case Bytecodes::_if_icmplt:
1285   case Bytecodes::_if_icmpne:
1286     {
1287       pop_int();
1288       pop_int();
1289       break;
1290     }
1291   case Bytecodes::_ifeq:
1292   case Bytecodes::_ifle:
1293   case Bytecodes::_iflt:
1294   case Bytecodes::_ifge:
1295   case Bytecodes::_ifgt:
1296   case Bytecodes::_ifne:
1297   case Bytecodes::_ireturn:
1298   case Bytecodes::_lookupswitch:
1299   case Bytecodes::_tableswitch:
1300     {
1301       pop_int();
1302       break;
1303     }
1304   case Bytecodes::_iinc:
1305     {
1306       int lnum = str->get_index();
1307       check_int(local(lnum));
1308       store_to_local(lnum);
1309       break;
1310     }
1311   case Bytecodes::_iload:   load_local_int(str->get_index()); break;
1312   case Bytecodes::_iload_0: load_local_int(0);                      break;
1313   case Bytecodes::_iload_1: load_local_int(1);                      break;
1314   case Bytecodes::_iload_2: load_local_int(2);                      break;
1315   case Bytecodes::_iload_3: load_local_int(3);                      break;
1316 
1317   case Bytecodes::_instanceof:
1318     {
1319       // Check for uncommon trap:
1320       do_checkcast(str);
1321       pop_object();
1322       push_int();
1323       break;
1324     }
1325   case Bytecodes::_invokeinterface: do_invoke(str, true);           break;
1326   case Bytecodes::_invokespecial:   do_invoke(str, true);           break;
1327   case Bytecodes::_invokestatic:    do_invoke(str, false);          break;
1328   case Bytecodes::_invokevirtual:   do_invoke(str, true);           break;
1329   case Bytecodes::_invokedynamic:   do_invoke(str, false);          break;
1330 
1331   case Bytecodes::_istore:   store_local_int(str->get_index());     break;
1332   case Bytecodes::_istore_0: store_local_int(0);                    break;
1333   case Bytecodes::_istore_1: store_local_int(1);                    break;
1334   case Bytecodes::_istore_2: store_local_int(2);                    break;
1335   case Bytecodes::_istore_3: store_local_int(3);                    break;
1336 
1337   case Bytecodes::_jsr:
1338   case Bytecodes::_jsr_w: do_jsr(str);                              break;
1339 
1340   case Bytecodes::_l2d:
1341     {
1342       pop_long();
1343       push_double();
1344       break;
1345     }
1346   case Bytecodes::_l2f:
1347     {
1348       pop_long();
1349       push_float();
1350       break;
1351     }
1352   case Bytecodes::_l2i:
1353     {
1354       pop_long();
1355       push_int();
1356       break;
1357     }
1358   case Bytecodes::_ladd:
1359   case Bytecodes::_land:
1360   case Bytecodes::_ldiv:
1361   case Bytecodes::_lmul:
1362   case Bytecodes::_lor:
1363   case Bytecodes::_lrem:
1364   case Bytecodes::_lsub:
1365   case Bytecodes::_lxor:
1366     {
1367       pop_long();
1368       pop_long();
1369       push_long();
1370       break;
1371     }
1372   case Bytecodes::_laload:
1373     {
1374       pop_int();
1375       ciTypeArrayKlass* array_klass = pop_typeArray();
1376       // Put assert here for right type?
1377       push_long();
1378       break;
1379     }
1380   case Bytecodes::_lastore:
1381     {
1382       pop_long();
1383       pop_int();
1384       pop_typeArray();
1385       // assert here?
1386       break;
1387     }
1388   case Bytecodes::_lcmp:
1389     {
1390       pop_long();
1391       pop_long();
1392       push_int();
1393       break;
1394     }
1395   case Bytecodes::_lconst_0:
1396   case Bytecodes::_lconst_1:
1397     {
1398       push_long();
1399       break;
1400     }
1401   case Bytecodes::_ldc:
1402   case Bytecodes::_ldc_w:
1403   case Bytecodes::_ldc2_w:
1404     {
1405       do_ldc(str);
1406       break;
1407     }
1408 
1409   case Bytecodes::_lload:   load_local_long(str->get_index());      break;
1410   case Bytecodes::_lload_0: load_local_long(0);                     break;
1411   case Bytecodes::_lload_1: load_local_long(1);                     break;
1412   case Bytecodes::_lload_2: load_local_long(2);                     break;
1413   case Bytecodes::_lload_3: load_local_long(3);                     break;
1414 
1415   case Bytecodes::_lneg:
1416     {
1417       pop_long();
1418       push_long();
1419       break;
1420     }
1421   case Bytecodes::_lreturn:
1422     {
1423       pop_long();
1424       break;
1425     }
1426   case Bytecodes::_lshl:
1427   case Bytecodes::_lshr:
1428   case Bytecodes::_lushr:
1429     {
1430       pop_int();
1431       pop_long();
1432       push_long();
1433       break;
1434     }
1435   case Bytecodes::_lstore:   store_local_long(str->get_index());    break;
1436   case Bytecodes::_lstore_0: store_local_long(0);                   break;
1437   case Bytecodes::_lstore_1: store_local_long(1);                   break;
1438   case Bytecodes::_lstore_2: store_local_long(2);                   break;
1439   case Bytecodes::_lstore_3: store_local_long(3);                   break;
1440 
1441   case Bytecodes::_multianewarray: do_multianewarray(str);          break;
1442 
1443   case Bytecodes::_new:      do_new(str);                           break;
1444 
1445   case Bytecodes::_newarray: do_newarray(str);                      break;
1446 
1447   case Bytecodes::_pop:
1448     {
1449       pop();
1450       break;
1451     }
1452   case Bytecodes::_pop2:
1453     {
1454       pop();
1455       pop();
1456       break;
1457     }
1458 
1459   case Bytecodes::_putfield:       do_putfield(str);                 break;
1460   case Bytecodes::_putstatic:      do_putstatic(str);                break;
1461 
1462   case Bytecodes::_ret: do_ret(str);                                 break;
1463 
1464   case Bytecodes::_swap:
1465     {
1466       ciType* value1 = pop_value();
1467       ciType* value2 = pop_value();
1468       push(value1);
1469       push(value2);
1470       break;
1471     }
1472   case Bytecodes::_wide:
1473   default:
1474     {
1475       // The iterator should skip this.
1476       ShouldNotReachHere();
1477       break;
1478     }
1479   }
1480 
1481   if (CITraceTypeFlow) {
1482     print_on(tty);
1483   }
1484 
1485   return (_trap_bci != -1);
1486 }
1487 
1488 #ifndef PRODUCT
1489 // ------------------------------------------------------------------
1490 // ciTypeFlow::StateVector::print_cell_on
1491 void ciTypeFlow::StateVector::print_cell_on(outputStream* st, Cell c) const {
1492   ciType* type = type_at(c);
1493   if (type == top_type()) {
1494     st->print("top");
1495   } else if (type == bottom_type()) {
1496     st->print("bottom");
1497   } else if (type == null_type()) {
1498     st->print("null");
1499   } else if (type == long2_type()) {
1500     st->print("long2");
1501   } else if (type == double2_type()) {
1502     st->print("double2");
1503   } else if (is_int(type)) {
1504     st->print("int");
1505   } else if (is_long(type)) {
1506     st->print("long");
1507   } else if (is_float(type)) {
1508     st->print("float");
1509   } else if (is_double(type)) {
1510     st->print("double");
1511   } else if (type->is_return_address()) {
1512     st->print("address(%d)", type->as_return_address()->bci());
1513   } else {
1514     if (type->is_klass()) {
1515       type->as_klass()->name()->print_symbol_on(st);
1516     } else {
1517       st->print("UNEXPECTED TYPE");
1518       type->print();
1519     }
1520   }
1521 }
1522 
1523 // ------------------------------------------------------------------
1524 // ciTypeFlow::StateVector::print_on
1525 void ciTypeFlow::StateVector::print_on(outputStream* st) const {
1526   int num_locals   = _outer->max_locals();
1527   int num_stack    = stack_size();
1528   int num_monitors = monitor_count();
1529   st->print_cr("  State : locals %d, stack %d, monitors %d", num_locals, num_stack, num_monitors);
1530   if (num_stack >= 0) {
1531     int i;
1532     for (i = 0; i < num_locals; i++) {
1533       st->print("    local %2d : ", i);
1534       print_cell_on(st, local(i));
1535       st->cr();
1536     }
1537     for (i = 0; i < num_stack; i++) {
1538       st->print("    stack %2d : ", i);
1539       print_cell_on(st, stack(i));
1540       st->cr();
1541     }
1542   }
1543 }
1544 #endif
1545 
1546 
1547 // ------------------------------------------------------------------
1548 // ciTypeFlow::SuccIter::next
1549 //
1550 void ciTypeFlow::SuccIter::next() {
1551   int succ_ct = _pred->successors()->length();
1552   int next = _index + 1;
1553   if (next < succ_ct) {
1554     _index = next;
1555     _succ = _pred->successors()->at(next);
1556     return;
1557   }
1558   for (int i = next - succ_ct; i < _pred->exceptions()->length(); i++) {
1559     // Do not compile any code for unloaded exception types.
1560     // Following compiler passes are responsible for doing this also.
1561     ciInstanceKlass* exception_klass = _pred->exc_klasses()->at(i);
1562     if (exception_klass->is_loaded()) {
1563       _index = next;
1564       _succ = _pred->exceptions()->at(i);
1565       return;
1566     }
1567     next++;
1568   }
1569   _index = -1;
1570   _succ = nullptr;
1571 }
1572 
1573 // ------------------------------------------------------------------
1574 // ciTypeFlow::SuccIter::set_succ
1575 //
1576 void ciTypeFlow::SuccIter::set_succ(Block* succ) {
1577   int succ_ct = _pred->successors()->length();
1578   if (_index < succ_ct) {
1579     _pred->successors()->at_put(_index, succ);
1580   } else {
1581     int idx = _index - succ_ct;
1582     _pred->exceptions()->at_put(idx, succ);
1583   }
1584 }
1585 
1586 // ciTypeFlow::Block
1587 //
1588 // A basic block.
1589 
1590 // ------------------------------------------------------------------
1591 // ciTypeFlow::Block::Block
1592 ciTypeFlow::Block::Block(ciTypeFlow* outer,
1593                          ciBlock *ciblk,
1594                          ciTypeFlow::JsrSet* jsrs) : _predecessors(outer->arena(), 1, 0, nullptr) {
1595   _ciblock = ciblk;
1596   _exceptions = nullptr;
1597   _exc_klasses = nullptr;
1598   _successors = nullptr;
1599   _state = new (outer->arena()) StateVector(outer);
1600   JsrSet* new_jsrs =
1601     new (outer->arena()) JsrSet(outer->arena(), jsrs->size());
1602   jsrs->copy_into(new_jsrs);
1603   _jsrs = new_jsrs;
1604   _next = nullptr;
1605   _on_work_list = false;
1606   _backedge_copy = false;
1607   _has_monitorenter = false;
1608   _trap_bci = -1;
1609   _trap_index = 0;
1610   df_init();
1611 
1612   if (CITraceTypeFlow) {
1613     tty->print_cr(">> Created new block");
1614     print_on(tty);
1615   }
1616 
1617   assert(this->outer() == outer, "outer link set up");
1618   assert(!outer->have_block_count(), "must not have mapped blocks yet");
1619 }
1620 
1621 // ------------------------------------------------------------------
1622 // ciTypeFlow::Block::df_init
1623 void ciTypeFlow::Block::df_init() {
1624   _pre_order = -1; assert(!has_pre_order(), "");
1625   _post_order = -1; assert(!has_post_order(), "");
1626   _loop = nullptr;
1627   _irreducible_loop_head = false;
1628   _irreducible_loop_secondary_entry = false;
1629   _rpo_next = nullptr;
1630 }
1631 
1632 // ------------------------------------------------------------------
1633 // ciTypeFlow::Block::successors
1634 //
1635 // Get the successors for this Block.
1636 GrowableArray<ciTypeFlow::Block*>*
1637 ciTypeFlow::Block::successors(ciBytecodeStream* str,
1638                               ciTypeFlow::StateVector* state,
1639                               ciTypeFlow::JsrSet* jsrs) {
1640   if (_successors == nullptr) {
1641     if (CITraceTypeFlow) {
1642       tty->print(">> Computing successors for block ");
1643       print_value_on(tty);
1644       tty->cr();
1645     }
1646 
1647     ciTypeFlow* analyzer = outer();
1648     Arena* arena = analyzer->arena();
1649     Block* block = nullptr;
1650     bool has_successor = !has_trap() &&
1651                          (control() != ciBlock::fall_through_bci || limit() < analyzer->code_size());
1652     if (!has_successor) {
1653       _successors =
1654         new (arena) GrowableArray<Block*>(arena, 1, 0, nullptr);
1655       // No successors
1656     } else if (control() == ciBlock::fall_through_bci) {
1657       assert(str->cur_bci() == limit(), "bad block end");
1658       // This block simply falls through to the next.
1659       _successors =
1660         new (arena) GrowableArray<Block*>(arena, 1, 0, nullptr);
1661 
1662       Block* block = analyzer->block_at(limit(), _jsrs);
1663       assert(_successors->length() == FALL_THROUGH, "");
1664       _successors->append(block);
1665     } else {
1666       int current_bci = str->cur_bci();
1667       int next_bci = str->next_bci();
1668       int branch_bci = -1;
1669       Block* target = nullptr;
1670       assert(str->next_bci() == limit(), "bad block end");
1671       // This block is not a simple fall-though.  Interpret
1672       // the current bytecode to find our successors.
1673       switch (str->cur_bc()) {
1674       case Bytecodes::_ifeq:         case Bytecodes::_ifne:
1675       case Bytecodes::_iflt:         case Bytecodes::_ifge:
1676       case Bytecodes::_ifgt:         case Bytecodes::_ifle:
1677       case Bytecodes::_if_icmpeq:    case Bytecodes::_if_icmpne:
1678       case Bytecodes::_if_icmplt:    case Bytecodes::_if_icmpge:
1679       case Bytecodes::_if_icmpgt:    case Bytecodes::_if_icmple:
1680       case Bytecodes::_if_acmpeq:    case Bytecodes::_if_acmpne:
1681       case Bytecodes::_ifnull:       case Bytecodes::_ifnonnull:
1682         // Our successors are the branch target and the next bci.
1683         branch_bci = str->get_dest();
1684         _successors =
1685           new (arena) GrowableArray<Block*>(arena, 2, 0, nullptr);
1686         assert(_successors->length() == IF_NOT_TAKEN, "");
1687         _successors->append(analyzer->block_at(next_bci, jsrs));
1688         assert(_successors->length() == IF_TAKEN, "");
1689         _successors->append(analyzer->block_at(branch_bci, jsrs));
1690         break;
1691 
1692       case Bytecodes::_goto:
1693         branch_bci = str->get_dest();
1694         _successors =
1695           new (arena) GrowableArray<Block*>(arena, 1, 0, nullptr);
1696         assert(_successors->length() == GOTO_TARGET, "");
1697         _successors->append(analyzer->block_at(branch_bci, jsrs));
1698         break;
1699 
1700       case Bytecodes::_jsr:
1701         branch_bci = str->get_dest();
1702         _successors =
1703           new (arena) GrowableArray<Block*>(arena, 1, 0, nullptr);
1704         assert(_successors->length() == GOTO_TARGET, "");
1705         _successors->append(analyzer->block_at(branch_bci, jsrs));
1706         break;
1707 
1708       case Bytecodes::_goto_w:
1709       case Bytecodes::_jsr_w:
1710         _successors =
1711           new (arena) GrowableArray<Block*>(arena, 1, 0, nullptr);
1712         assert(_successors->length() == GOTO_TARGET, "");
1713         _successors->append(analyzer->block_at(str->get_far_dest(), jsrs));
1714         break;
1715 
1716       case Bytecodes::_tableswitch:  {
1717         Bytecode_tableswitch tableswitch(str);
1718 
1719         int len = tableswitch.length();
1720         _successors =
1721           new (arena) GrowableArray<Block*>(arena, len+1, 0, nullptr);
1722         int bci = current_bci + tableswitch.default_offset();
1723         Block* block = analyzer->block_at(bci, jsrs);
1724         assert(_successors->length() == SWITCH_DEFAULT, "");
1725         _successors->append(block);
1726         while (--len >= 0) {
1727           int bci = current_bci + tableswitch.dest_offset_at(len);
1728           block = analyzer->block_at(bci, jsrs);
1729           assert(_successors->length() >= SWITCH_CASES, "");
1730           _successors->append_if_missing(block);
1731         }
1732         break;
1733       }
1734 
1735       case Bytecodes::_lookupswitch: {
1736         Bytecode_lookupswitch lookupswitch(str);
1737 
1738         int npairs = lookupswitch.number_of_pairs();
1739         _successors =
1740           new (arena) GrowableArray<Block*>(arena, npairs+1, 0, nullptr);
1741         int bci = current_bci + lookupswitch.default_offset();
1742         Block* block = analyzer->block_at(bci, jsrs);
1743         assert(_successors->length() == SWITCH_DEFAULT, "");
1744         _successors->append(block);
1745         while(--npairs >= 0) {
1746           LookupswitchPair pair = lookupswitch.pair_at(npairs);
1747           int bci = current_bci + pair.offset();
1748           Block* block = analyzer->block_at(bci, jsrs);
1749           assert(_successors->length() >= SWITCH_CASES, "");
1750           _successors->append_if_missing(block);
1751         }
1752         break;
1753       }
1754 
1755       case Bytecodes::_athrow:     case Bytecodes::_ireturn:
1756       case Bytecodes::_lreturn:    case Bytecodes::_freturn:
1757       case Bytecodes::_dreturn:    case Bytecodes::_areturn:
1758       case Bytecodes::_return:
1759         _successors =
1760           new (arena) GrowableArray<Block*>(arena, 1, 0, nullptr);
1761         // No successors
1762         break;
1763 
1764       case Bytecodes::_ret: {
1765         _successors =
1766           new (arena) GrowableArray<Block*>(arena, 1, 0, nullptr);
1767 
1768         Cell local = state->local(str->get_index());
1769         ciType* return_address = state->type_at(local);
1770         assert(return_address->is_return_address(), "verify: wrong type");
1771         int bci = return_address->as_return_address()->bci();
1772         assert(_successors->length() == GOTO_TARGET, "");
1773         _successors->append(analyzer->block_at(bci, jsrs));
1774         break;
1775       }
1776 
1777       case Bytecodes::_wide:
1778       default:
1779         ShouldNotReachHere();
1780         break;
1781       }
1782     }
1783 
1784     // Set predecessor information
1785     for (int i = 0; i < _successors->length(); i++) {
1786       Block* block = _successors->at(i);
1787       block->predecessors()->append(this);
1788     }
1789   }
1790   return _successors;
1791 }
1792 
1793 // ------------------------------------------------------------------
1794 // ciTypeFlow::Block:compute_exceptions
1795 //
1796 // Compute the exceptional successors and types for this Block.
1797 void ciTypeFlow::Block::compute_exceptions() {
1798   assert(_exceptions == nullptr && _exc_klasses == nullptr, "repeat");
1799 
1800   if (CITraceTypeFlow) {
1801     tty->print(">> Computing exceptions for block ");
1802     print_value_on(tty);
1803     tty->cr();
1804   }
1805 
1806   ciTypeFlow* analyzer = outer();
1807   Arena* arena = analyzer->arena();
1808 
1809   // Any bci in the block will do.
1810   ciExceptionHandlerStream str(analyzer->method(), start());
1811 
1812   // Allocate our growable arrays.
1813   int exc_count = str.count();
1814   _exceptions = new (arena) GrowableArray<Block*>(arena, exc_count, 0, nullptr);
1815   _exc_klasses = new (arena) GrowableArray<ciInstanceKlass*>(arena, exc_count,
1816                                                              0, nullptr);
1817 
1818   for ( ; !str.is_done(); str.next()) {
1819     ciExceptionHandler* handler = str.handler();
1820     int bci = handler->handler_bci();
1821     ciInstanceKlass* klass = nullptr;
1822     if (bci == -1) {
1823       // There is no catch all.  It is possible to exit the method.
1824       break;
1825     }
1826     if (handler->is_catch_all()) {
1827       klass = analyzer->env()->Throwable_klass();
1828     } else {
1829       klass = handler->catch_klass();
1830     }
1831     Block* block = analyzer->block_at(bci, _jsrs);
1832     _exceptions->append(block);
1833     block->predecessors()->append(this);
1834     _exc_klasses->append(klass);
1835   }
1836 }
1837 
1838 // ------------------------------------------------------------------
1839 // ciTypeFlow::Block::set_backedge_copy
1840 // Use this only to make a pre-existing public block into a backedge copy.
1841 void ciTypeFlow::Block::set_backedge_copy(bool z) {
1842   assert(z || (z == is_backedge_copy()), "cannot make a backedge copy public");
1843   _backedge_copy = z;
1844 }
1845 
1846 // Analogous to PhaseIdealLoop::is_in_irreducible_loop
1847 bool ciTypeFlow::Block::is_in_irreducible_loop() const {
1848   if (!outer()->has_irreducible_entry()) {
1849     return false; // No irreducible loop in method.
1850   }
1851   Loop* lp = loop(); // Innermost loop containing block.
1852   if (lp == nullptr) {
1853     assert(!is_post_visited(), "must have enclosing loop once post-visited");
1854     return false; // Not yet processed, so we do not know, yet.
1855   }
1856   // Walk all the way up the loop-tree, search for an irreducible loop.
1857   do {
1858     if (lp->is_irreducible()) {
1859       return true; // We are in irreducible loop.
1860     }
1861     if (lp->head()->pre_order() == 0) {
1862       return false; // Found root loop, terminate.
1863     }
1864     lp = lp->parent();
1865   } while (lp != nullptr);
1866   // We have "lp->parent() == nullptr", which happens only for infinite loops,
1867   // where no parent is attached to the loop. We did not find any irreducible
1868   // loop from this block out to lp. Thus lp only has one entry, and no exit
1869   // (it is infinite and reducible). We can always rewrite an infinite loop
1870   // that is nested inside other loops:
1871   // while(condition) { infinite_loop; }
1872   // with an equivalent program where the infinite loop is an outermost loop
1873   // that is not nested in any loop:
1874   // while(condition) { break; } infinite_loop;
1875   // Thus, we can understand lp as an outermost loop, and can terminate and
1876   // conclude: this block is in no irreducible loop.
1877   return false;
1878 }
1879 
1880 // ------------------------------------------------------------------
1881 // ciTypeFlow::Block::is_clonable_exit
1882 //
1883 // At most 2 normal successors, one of which continues looping,
1884 // and all exceptional successors must exit.
1885 bool ciTypeFlow::Block::is_clonable_exit(ciTypeFlow::Loop* lp) {
1886   int normal_cnt  = 0;
1887   int in_loop_cnt = 0;
1888   for (SuccIter iter(this); !iter.done(); iter.next()) {
1889     Block* succ = iter.succ();
1890     if (iter.is_normal_ctrl()) {
1891       if (++normal_cnt > 2) return false;
1892       if (lp->contains(succ->loop())) {
1893         if (++in_loop_cnt > 1) return false;
1894       }
1895     } else {
1896       if (lp->contains(succ->loop())) return false;
1897     }
1898   }
1899   return in_loop_cnt == 1;
1900 }
1901 
1902 // ------------------------------------------------------------------
1903 // ciTypeFlow::Block::looping_succ
1904 //
1905 ciTypeFlow::Block* ciTypeFlow::Block::looping_succ(ciTypeFlow::Loop* lp) {
1906   assert(successors()->length() <= 2, "at most 2 normal successors");
1907   for (SuccIter iter(this); !iter.done(); iter.next()) {
1908     Block* succ = iter.succ();
1909     if (lp->contains(succ->loop())) {
1910       return succ;
1911     }
1912   }
1913   return nullptr;
1914 }
1915 
1916 #ifndef PRODUCT
1917 // ------------------------------------------------------------------
1918 // ciTypeFlow::Block::print_value_on
1919 void ciTypeFlow::Block::print_value_on(outputStream* st) const {
1920   if (has_pre_order()) st->print("#%-2d ", pre_order());
1921   if (has_rpo())       st->print("rpo#%-2d ", rpo());
1922   st->print("[%d - %d)", start(), limit());
1923   if (is_loop_head()) st->print(" lphd");
1924   if (is_in_irreducible_loop()) st->print(" in_irred");
1925   if (is_irreducible_loop_head()) st->print(" irred_head");
1926   if (is_irreducible_loop_secondary_entry()) st->print(" irred_entry");
1927   if (_jsrs->size() > 0) { st->print("/");  _jsrs->print_on(st); }
1928   if (is_backedge_copy())  st->print("/backedge_copy");
1929 }
1930 
1931 // ------------------------------------------------------------------
1932 // ciTypeFlow::Block::print_on
1933 void ciTypeFlow::Block::print_on(outputStream* st) const {
1934   if ((Verbose || WizardMode) && (limit() >= 0)) {
1935     // Don't print 'dummy' blocks (i.e. blocks with limit() '-1')
1936     outer()->method()->print_codes_on(start(), limit(), st);
1937   }
1938   st->print_cr("  ====================================================  ");
1939   st->print ("  ");
1940   print_value_on(st);
1941   st->print(" Stored locals: "); def_locals()->print_on(st, outer()->method()->max_locals()); tty->cr();
1942   if (loop() && loop()->parent() != nullptr) {
1943     st->print(" loops:");
1944     Loop* lp = loop();
1945     do {
1946       st->print(" %d<-%d", lp->head()->pre_order(),lp->tail()->pre_order());
1947       if (lp->is_irreducible()) st->print("(ir)");
1948       lp = lp->parent();
1949     } while (lp->parent() != nullptr);
1950   }
1951   st->cr();
1952   _state->print_on(st);
1953   if (_successors == nullptr) {
1954     st->print_cr("  No successor information");
1955   } else {
1956     int num_successors = _successors->length();
1957     st->print_cr("  Successors : %d", num_successors);
1958     for (int i = 0; i < num_successors; i++) {
1959       Block* successor = _successors->at(i);
1960       st->print("    ");
1961       successor->print_value_on(st);
1962       st->cr();
1963     }
1964   }
1965   if (_predecessors.is_empty()) {
1966     st->print_cr("  No predecessor information");
1967   } else {
1968     int num_predecessors = _predecessors.length();
1969     st->print_cr("  Predecessors : %d", num_predecessors);
1970     for (int i = 0; i < num_predecessors; i++) {
1971       Block* predecessor = _predecessors.at(i);
1972       st->print("    ");
1973       predecessor->print_value_on(st);
1974       st->cr();
1975     }
1976   }
1977   if (_exceptions == nullptr) {
1978     st->print_cr("  No exception information");
1979   } else {
1980     int num_exceptions = _exceptions->length();
1981     st->print_cr("  Exceptions : %d", num_exceptions);
1982     for (int i = 0; i < num_exceptions; i++) {
1983       Block* exc_succ = _exceptions->at(i);
1984       ciInstanceKlass* exc_klass = _exc_klasses->at(i);
1985       st->print("    ");
1986       exc_succ->print_value_on(st);
1987       st->print(" -- ");
1988       exc_klass->name()->print_symbol_on(st);
1989       st->cr();
1990     }
1991   }
1992   if (has_trap()) {
1993     st->print_cr("  Traps on %d with trap index %d", trap_bci(), trap_index());
1994   }
1995   st->print_cr("  ====================================================  ");
1996 }
1997 #endif
1998 
1999 #ifndef PRODUCT
2000 // ------------------------------------------------------------------
2001 // ciTypeFlow::LocalSet::print_on
2002 void ciTypeFlow::LocalSet::print_on(outputStream* st, int limit) const {
2003   st->print("{");
2004   for (int i = 0; i < max; i++) {
2005     if (test(i)) st->print(" %d", i);
2006   }
2007   if (limit > max) {
2008     st->print(" %d..%d ", max, limit);
2009   }
2010   st->print(" }");
2011 }
2012 #endif
2013 
2014 // ciTypeFlow
2015 //
2016 // This is a pass over the bytecodes which computes the following:
2017 //   basic block structure
2018 //   interpreter type-states (a la the verifier)
2019 
2020 // ------------------------------------------------------------------
2021 // ciTypeFlow::ciTypeFlow
2022 ciTypeFlow::ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci) {
2023   _env = env;
2024   _method = method;
2025   _has_irreducible_entry = false;
2026   _osr_bci = osr_bci;
2027   _failure_reason = nullptr;
2028   assert(0 <= start_bci() && start_bci() < code_size() , "correct osr_bci argument: 0 <= %d < %d", start_bci(), code_size());
2029   _work_list = nullptr;
2030 
2031   int ciblock_count = _method->get_method_blocks()->num_blocks();
2032   _idx_to_blocklist = NEW_ARENA_ARRAY(arena(), GrowableArray<Block*>*, ciblock_count);
2033   for (int i = 0; i < ciblock_count; i++) {
2034     _idx_to_blocklist[i] = nullptr;
2035   }
2036   _block_map = nullptr;  // until all blocks are seen
2037   _jsr_records = nullptr;
2038 }
2039 
2040 // ------------------------------------------------------------------
2041 // ciTypeFlow::work_list_next
2042 //
2043 // Get the next basic block from our work list.
2044 ciTypeFlow::Block* ciTypeFlow::work_list_next() {
2045   assert(!work_list_empty(), "work list must not be empty");
2046   Block* next_block = _work_list;
2047   _work_list = next_block->next();
2048   next_block->set_next(nullptr);
2049   next_block->set_on_work_list(false);
2050   return next_block;
2051 }
2052 
2053 // ------------------------------------------------------------------
2054 // ciTypeFlow::add_to_work_list
2055 //
2056 // Add a basic block to our work list.
2057 // List is sorted by decreasing postorder sort (same as increasing RPO)
2058 void ciTypeFlow::add_to_work_list(ciTypeFlow::Block* block) {
2059   assert(!block->is_on_work_list(), "must not already be on work list");
2060 
2061   if (CITraceTypeFlow) {
2062     tty->print(">> Adding block ");
2063     block->print_value_on(tty);
2064     tty->print_cr(" to the work list : ");
2065   }
2066 
2067   block->set_on_work_list(true);
2068 
2069   // decreasing post order sort
2070 
2071   Block* prev = nullptr;
2072   Block* current = _work_list;
2073   int po = block->post_order();
2074   while (current != nullptr) {
2075     if (!current->has_post_order() || po > current->post_order())
2076       break;
2077     prev = current;
2078     current = current->next();
2079   }
2080   if (prev == nullptr) {
2081     block->set_next(_work_list);
2082     _work_list = block;
2083   } else {
2084     block->set_next(current);
2085     prev->set_next(block);
2086   }
2087 
2088   if (CITraceTypeFlow) {
2089     tty->cr();
2090   }
2091 }
2092 
2093 // ------------------------------------------------------------------
2094 // ciTypeFlow::block_at
2095 //
2096 // Return the block beginning at bci which has a JsrSet compatible
2097 // with jsrs.
2098 ciTypeFlow::Block* ciTypeFlow::block_at(int bci, ciTypeFlow::JsrSet* jsrs, CreateOption option) {
2099   // First find the right ciBlock.
2100   if (CITraceTypeFlow) {
2101     tty->print(">> Requesting block for %d/", bci);
2102     jsrs->print_on(tty);
2103     tty->cr();
2104   }
2105 
2106   ciBlock* ciblk = _method->get_method_blocks()->block_containing(bci);
2107   assert(ciblk->start_bci() == bci, "bad ciBlock boundaries");
2108   Block* block = get_block_for(ciblk->index(), jsrs, option);
2109 
2110   assert(block == nullptr? (option == no_create): block->is_backedge_copy() == (option == create_backedge_copy), "create option consistent with result");
2111 
2112   if (CITraceTypeFlow) {
2113     if (block != nullptr) {
2114       tty->print(">> Found block ");
2115       block->print_value_on(tty);
2116       tty->cr();
2117     } else {
2118       tty->print_cr(">> No such block.");
2119     }
2120   }
2121 
2122   return block;
2123 }
2124 
2125 // ------------------------------------------------------------------
2126 // ciTypeFlow::make_jsr_record
2127 //
2128 // Make a JsrRecord for a given (entry, return) pair, if such a record
2129 // does not already exist.
2130 ciTypeFlow::JsrRecord* ciTypeFlow::make_jsr_record(int entry_address,
2131                                                    int return_address) {
2132   if (_jsr_records == nullptr) {
2133     _jsr_records = new (arena()) GrowableArray<JsrRecord*>(arena(),
2134                                                            2,
2135                                                            0,
2136                                                            nullptr);
2137   }
2138   JsrRecord* record = nullptr;
2139   int len = _jsr_records->length();
2140   for (int i = 0; i < len; i++) {
2141     JsrRecord* record = _jsr_records->at(i);
2142     if (record->entry_address() == entry_address &&
2143         record->return_address() == return_address) {
2144       return record;
2145     }
2146   }
2147 
2148   record = new (arena()) JsrRecord(entry_address, return_address);
2149   _jsr_records->append(record);
2150   return record;
2151 }
2152 
2153 // ------------------------------------------------------------------
2154 // ciTypeFlow::flow_exceptions
2155 //
2156 // Merge the current state into all exceptional successors at the
2157 // current point in the code.
2158 void ciTypeFlow::flow_exceptions(GrowableArray<ciTypeFlow::Block*>* exceptions,
2159                                  GrowableArray<ciInstanceKlass*>* exc_klasses,
2160                                  ciTypeFlow::StateVector* state) {
2161   int len = exceptions->length();
2162   assert(exc_klasses->length() == len, "must have same length");
2163   for (int i = 0; i < len; i++) {
2164     Block* block = exceptions->at(i);
2165     ciInstanceKlass* exception_klass = exc_klasses->at(i);
2166 
2167     if (!exception_klass->is_loaded()) {
2168       // Do not compile any code for unloaded exception types.
2169       // Following compiler passes are responsible for doing this also.
2170       continue;
2171     }
2172 
2173     if (block->meet_exception(exception_klass, state)) {
2174       // Block was modified and has PO.  Add it to the work list.
2175       if (block->has_post_order() &&
2176           !block->is_on_work_list()) {
2177         add_to_work_list(block);
2178       }
2179     }
2180   }
2181 }
2182 
2183 // ------------------------------------------------------------------
2184 // ciTypeFlow::flow_successors
2185 //
2186 // Merge the current state into all successors at the current point
2187 // in the code.
2188 void ciTypeFlow::flow_successors(GrowableArray<ciTypeFlow::Block*>* successors,
2189                                  ciTypeFlow::StateVector* state) {
2190   int len = successors->length();
2191   for (int i = 0; i < len; i++) {
2192     Block* block = successors->at(i);
2193     if (block->meet(state)) {
2194       // Block was modified and has PO.  Add it to the work list.
2195       if (block->has_post_order() &&
2196           !block->is_on_work_list()) {
2197         add_to_work_list(block);
2198       }
2199     }
2200   }
2201 }
2202 
2203 // ------------------------------------------------------------------
2204 // ciTypeFlow::can_trap
2205 //
2206 // Tells if a given instruction is able to generate an exception edge.
2207 bool ciTypeFlow::can_trap(ciBytecodeStream& str) {
2208   // Cf. GenerateOopMap::do_exception_edge.
2209   if (!Bytecodes::can_trap(str.cur_bc()))  return false;
2210 
2211   switch (str.cur_bc()) {
2212     // %%% FIXME: ldc of Class can generate an exception
2213     case Bytecodes::_ldc:
2214     case Bytecodes::_ldc_w:
2215     case Bytecodes::_ldc2_w:
2216       return str.is_in_error();
2217 
2218     case Bytecodes::_aload_0:
2219       // These bytecodes can trap for rewriting.  We need to assume that
2220       // they do not throw exceptions to make the monitor analysis work.
2221       return false;
2222 
2223     case Bytecodes::_ireturn:
2224     case Bytecodes::_lreturn:
2225     case Bytecodes::_freturn:
2226     case Bytecodes::_dreturn:
2227     case Bytecodes::_areturn:
2228     case Bytecodes::_return:
2229       // We can assume the monitor stack is empty in this analysis.
2230       return false;
2231 
2232     case Bytecodes::_monitorexit:
2233       // We can assume monitors are matched in this analysis.
2234       return false;
2235 
2236     default:
2237       return true;
2238   }
2239 }
2240 
2241 // ------------------------------------------------------------------
2242 // ciTypeFlow::clone_loop_heads
2243 //
2244 // Clone the loop heads
2245 bool ciTypeFlow::clone_loop_heads(StateVector* temp_vector, JsrSet* temp_set) {
2246   bool rslt = false;
2247   for (PreorderLoops iter(loop_tree_root()); !iter.done(); iter.next()) {
2248     Loop* lp = iter.current();
2249     Block* head = lp->head();
2250     if (lp == loop_tree_root() ||
2251         lp->is_irreducible() ||
2252         !head->is_clonable_exit(lp))
2253       continue;
2254 
2255     // Avoid BoxLock merge.
2256     if (EliminateNestedLocks && head->has_monitorenter())
2257       continue;
2258 
2259     // check not already cloned
2260     if (head->backedge_copy_count() != 0)
2261       continue;
2262 
2263     // Don't clone head of OSR loop to get correct types in start block.
2264     if (is_osr_flow() && head->start() == start_bci())
2265       continue;
2266 
2267     // check _no_ shared head below us
2268     Loop* ch;
2269     for (ch = lp->child(); ch != nullptr && ch->head() != head; ch = ch->sibling());
2270     if (ch != nullptr)
2271       continue;
2272 
2273     // Clone head
2274     Block* new_head = head->looping_succ(lp);
2275     Block* clone = clone_loop_head(lp, temp_vector, temp_set);
2276     // Update lp's info
2277     clone->set_loop(lp);
2278     lp->set_head(new_head);
2279     lp->set_tail(clone);
2280     // And move original head into outer loop
2281     head->set_loop(lp->parent());
2282 
2283     rslt = true;
2284   }
2285   return rslt;
2286 }
2287 
2288 // ------------------------------------------------------------------
2289 // ciTypeFlow::clone_loop_head
2290 //
2291 // Clone lp's head and replace tail's successors with clone.
2292 //
2293 //  |
2294 //  v
2295 // head <-> body
2296 //  |
2297 //  v
2298 // exit
2299 //
2300 // new_head
2301 //
2302 //  |
2303 //  v
2304 // head ----------\
2305 //  |             |
2306 //  |             v
2307 //  |  clone <-> body
2308 //  |    |
2309 //  | /--/
2310 //  | |
2311 //  v v
2312 // exit
2313 //
2314 ciTypeFlow::Block* ciTypeFlow::clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set) {
2315   Block* head = lp->head();
2316   Block* tail = lp->tail();
2317   if (CITraceTypeFlow) {
2318     tty->print(">> Requesting clone of loop head "); head->print_value_on(tty);
2319     tty->print("  for predecessor ");                tail->print_value_on(tty);
2320     tty->cr();
2321   }
2322   Block* clone = block_at(head->start(), head->jsrs(), create_backedge_copy);
2323   assert(clone->backedge_copy_count() == 1, "one backedge copy for all back edges");
2324 
2325   assert(!clone->has_pre_order(), "just created");
2326   clone->set_next_pre_order();
2327 
2328   // Accumulate profiled count for all backedges that share this loop's head
2329   int total_count = lp->profiled_count();
2330   for (Loop* lp1 = lp->parent(); lp1 != nullptr; lp1 = lp1->parent()) {
2331     for (Loop* lp2 = lp1; lp2 != nullptr; lp2 = lp2->sibling()) {
2332       if (lp2->head() == head && !lp2->tail()->is_backedge_copy()) {
2333         total_count += lp2->profiled_count();
2334       }
2335     }
2336   }
2337   // Have the most frequent ones branch to the clone instead
2338   int count = 0;
2339   int loops_with_shared_head = 0;
2340   Block* latest_tail = tail;
2341   bool done = false;
2342   for (Loop* lp1 = lp; lp1 != nullptr && !done; lp1 = lp1->parent()) {
2343     for (Loop* lp2 = lp1; lp2 != nullptr && !done; lp2 = lp2->sibling()) {
2344       if (lp2->head() == head && !lp2->tail()->is_backedge_copy()) {
2345         count += lp2->profiled_count();
2346         if (lp2->tail()->post_order() < latest_tail->post_order()) {
2347           latest_tail = lp2->tail();
2348         }
2349         loops_with_shared_head++;
2350         for (SuccIter iter(lp2->tail()); !iter.done(); iter.next()) {
2351           if (iter.succ() == head) {
2352             iter.set_succ(clone);
2353             // Update predecessor information
2354             head->predecessors()->remove(lp2->tail());
2355             clone->predecessors()->append(lp2->tail());
2356           }
2357         }
2358         flow_block(lp2->tail(), temp_vector, temp_set);
2359         if (lp2->head() == lp2->tail()) {
2360           // For self-loops, clone->head becomes clone->clone
2361           flow_block(clone, temp_vector, temp_set);
2362           for (SuccIter iter(clone); !iter.done(); iter.next()) {
2363             if (iter.succ() == lp2->head()) {
2364               iter.set_succ(clone);
2365               // Update predecessor information
2366               lp2->head()->predecessors()->remove(clone);
2367               clone->predecessors()->append(clone);
2368               break;
2369             }
2370           }
2371         }
2372         if (total_count == 0 || count > (total_count * .9)) {
2373           done = true;
2374         }
2375       }
2376     }
2377   }
2378   assert(loops_with_shared_head >= 1, "at least one new");
2379   clone->set_rpo_next(latest_tail->rpo_next());
2380   latest_tail->set_rpo_next(clone);
2381   flow_block(clone, temp_vector, temp_set);
2382 
2383   return clone;
2384 }
2385 
2386 // ------------------------------------------------------------------
2387 // ciTypeFlow::flow_block
2388 //
2389 // Interpret the effects of the bytecodes on the incoming state
2390 // vector of a basic block.  Push the changed state to succeeding
2391 // basic blocks.
2392 void ciTypeFlow::flow_block(ciTypeFlow::Block* block,
2393                             ciTypeFlow::StateVector* state,
2394                             ciTypeFlow::JsrSet* jsrs) {
2395   if (CITraceTypeFlow) {
2396     tty->print("\n>> ANALYZING BLOCK : ");
2397     tty->cr();
2398     block->print_on(tty);
2399   }
2400   assert(block->has_pre_order(), "pre-order is assigned before 1st flow");
2401 
2402   int start = block->start();
2403   int limit = block->limit();
2404   int control = block->control();
2405   if (control != ciBlock::fall_through_bci) {
2406     limit = control;
2407   }
2408 
2409   // Grab the state from the current block.
2410   block->copy_state_into(state);
2411   state->def_locals()->clear();
2412 
2413   GrowableArray<Block*>*           exceptions = block->exceptions();
2414   GrowableArray<ciInstanceKlass*>* exc_klasses = block->exc_klasses();
2415   bool has_exceptions = exceptions->length() > 0;
2416 
2417   bool exceptions_used = false;
2418 
2419   ciBytecodeStream str(method());
2420   str.reset_to_bci(start);
2421   Bytecodes::Code code;
2422   while ((code = str.next()) != ciBytecodeStream::EOBC() &&
2423          str.cur_bci() < limit) {
2424     // Check for exceptional control flow from this point.
2425     if (has_exceptions && can_trap(str)) {
2426       flow_exceptions(exceptions, exc_klasses, state);
2427       exceptions_used = true;
2428     }
2429     // Apply the effects of the current bytecode to our state.
2430     bool res = state->apply_one_bytecode(&str);
2431 
2432     // Watch for bailouts.
2433     if (failing())  return;
2434 
2435     if (str.cur_bc() == Bytecodes::_monitorenter) {
2436       block->set_has_monitorenter();
2437     }
2438 
2439     if (res) {
2440 
2441       // We have encountered a trap.  Record it in this block.
2442       block->set_trap(state->trap_bci(), state->trap_index());
2443 
2444       if (CITraceTypeFlow) {
2445         tty->print_cr(">> Found trap");
2446         block->print_on(tty);
2447       }
2448 
2449       // Save set of locals defined in this block
2450       block->def_locals()->add(state->def_locals());
2451 
2452       // Record (no) successors.
2453       block->successors(&str, state, jsrs);
2454 
2455       assert(!has_exceptions || exceptions_used, "Not removing exceptions");
2456 
2457       // Discontinue interpretation of this Block.
2458       return;
2459     }
2460   }
2461 
2462   GrowableArray<Block*>* successors = nullptr;
2463   if (control != ciBlock::fall_through_bci) {
2464     // Check for exceptional control flow from this point.
2465     if (has_exceptions && can_trap(str)) {
2466       flow_exceptions(exceptions, exc_klasses, state);
2467       exceptions_used = true;
2468     }
2469 
2470     // Fix the JsrSet to reflect effect of the bytecode.
2471     block->copy_jsrs_into(jsrs);
2472     jsrs->apply_control(this, &str, state);
2473 
2474     // Find successor edges based on old state and new JsrSet.
2475     successors = block->successors(&str, state, jsrs);
2476 
2477     // Apply the control changes to the state.
2478     state->apply_one_bytecode(&str);
2479   } else {
2480     // Fall through control
2481     successors = block->successors(&str, nullptr, nullptr);
2482   }
2483 
2484   // Save set of locals defined in this block
2485   block->def_locals()->add(state->def_locals());
2486 
2487   // Remove untaken exception paths
2488   if (!exceptions_used)
2489     exceptions->clear();
2490 
2491   // Pass our state to successors.
2492   flow_successors(successors, state);
2493 }
2494 
2495 // ------------------------------------------------------------------
2496 // ciTypeFlow::PreOrderLoops::next
2497 //
2498 // Advance to next loop tree using a preorder, left-to-right traversal.
2499 void ciTypeFlow::PreorderLoops::next() {
2500   assert(!done(), "must not be done.");
2501   if (_current->child() != nullptr) {
2502     _current = _current->child();
2503   } else if (_current->sibling() != nullptr) {
2504     _current = _current->sibling();
2505   } else {
2506     while (_current != _root && _current->sibling() == nullptr) {
2507       _current = _current->parent();
2508     }
2509     if (_current == _root) {
2510       _current = nullptr;
2511       assert(done(), "must be done.");
2512     } else {
2513       assert(_current->sibling() != nullptr, "must be more to do");
2514       _current = _current->sibling();
2515     }
2516   }
2517 }
2518 
2519 // If the tail is a branch to the head, retrieve how many times that path was taken from profiling
2520 int ciTypeFlow::Loop::profiled_count() {
2521   if (_profiled_count >= 0) {
2522     return _profiled_count;
2523   }
2524   ciMethodData* methodData = outer()->method()->method_data();
2525   if (!methodData->is_mature()) {
2526     _profiled_count = 0;
2527     return 0;
2528   }
2529   ciTypeFlow::Block* tail = this->tail();
2530   if (tail->control() == -1 || tail->has_trap()) {
2531     _profiled_count = 0;
2532     return 0;
2533   }
2534 
2535   ciProfileData* data = methodData->bci_to_data(tail->control());
2536 
2537   if (data == nullptr || !data->is_JumpData()) {
2538     _profiled_count = 0;
2539     return 0;
2540   }
2541 
2542   ciBytecodeStream iter(outer()->method());
2543   iter.reset_to_bci(tail->control());
2544 
2545   bool is_an_if = false;
2546   bool wide = false;
2547   Bytecodes::Code bc = iter.next();
2548   switch (bc) {
2549     case Bytecodes::_ifeq:
2550     case Bytecodes::_ifne:
2551     case Bytecodes::_iflt:
2552     case Bytecodes::_ifge:
2553     case Bytecodes::_ifgt:
2554     case Bytecodes::_ifle:
2555     case Bytecodes::_if_icmpeq:
2556     case Bytecodes::_if_icmpne:
2557     case Bytecodes::_if_icmplt:
2558     case Bytecodes::_if_icmpge:
2559     case Bytecodes::_if_icmpgt:
2560     case Bytecodes::_if_icmple:
2561     case Bytecodes::_if_acmpeq:
2562     case Bytecodes::_if_acmpne:
2563     case Bytecodes::_ifnull:
2564     case Bytecodes::_ifnonnull:
2565       is_an_if = true;
2566       break;
2567     case Bytecodes::_goto_w:
2568     case Bytecodes::_jsr_w:
2569       wide = true;
2570       break;
2571     case Bytecodes::_goto:
2572     case Bytecodes::_jsr:
2573       break;
2574     default:
2575       fatal(" invalid bytecode: %s", Bytecodes::name(iter.cur_bc()));
2576   }
2577 
2578   GrowableArray<ciTypeFlow::Block*>* succs = tail->successors();
2579 
2580   if (!is_an_if) {
2581     assert(((wide ? iter.get_far_dest() : iter.get_dest()) == head()->start()) == (succs->at(ciTypeFlow::GOTO_TARGET) == head()), "branch should lead to loop head");
2582     if (succs->at(ciTypeFlow::GOTO_TARGET) == head()) {
2583       _profiled_count = outer()->method()->scale_count(data->as_JumpData()->taken());
2584       return _profiled_count;
2585     }
2586   } else {
2587     assert((iter.get_dest() == head()->start()) == (succs->at(ciTypeFlow::IF_TAKEN) == head()), "bytecode and CFG not consistent");
2588     assert((tail->limit() == head()->start()) == (succs->at(ciTypeFlow::IF_NOT_TAKEN) == head()), "bytecode and CFG not consistent");
2589     if (succs->at(ciTypeFlow::IF_TAKEN) == head()) {
2590       _profiled_count = outer()->method()->scale_count(data->as_JumpData()->taken());
2591       return _profiled_count;
2592     } else if (succs->at(ciTypeFlow::IF_NOT_TAKEN) == head()) {
2593       _profiled_count = outer()->method()->scale_count(data->as_BranchData()->not_taken());
2594       return _profiled_count;
2595     }
2596   }
2597 
2598   _profiled_count = 0;
2599   return _profiled_count;
2600 }
2601 
2602 bool ciTypeFlow::Loop::at_insertion_point(Loop* lp, Loop* current) {
2603   int lp_pre_order = lp->head()->pre_order();
2604   if (current->head()->pre_order() < lp_pre_order) {
2605     return true;
2606   } else if (current->head()->pre_order() > lp_pre_order) {
2607     return false;
2608   }
2609   // In the case of a shared head, make the most frequent head/tail (as reported by profiling) the inner loop
2610   if (current->head() == lp->head()) {
2611     int lp_count = lp->profiled_count();
2612     int current_count = current->profiled_count();
2613     if (current_count < lp_count) {
2614       return true;
2615     } else if (current_count > lp_count) {
2616       return false;
2617     }
2618   }
2619   if (current->tail()->pre_order() > lp->tail()->pre_order()) {
2620     return true;
2621   }
2622   return false;
2623 }
2624 
2625 // ------------------------------------------------------------------
2626 // ciTypeFlow::Loop::sorted_merge
2627 //
2628 // Merge the branch lp into this branch, sorting on the loop head
2629 // pre_orders. Returns the leaf of the merged branch.
2630 // Child and sibling pointers will be setup later.
2631 // Sort is (looking from leaf towards the root)
2632 //  descending on primary key: loop head's pre_order, and
2633 //  ascending  on secondary key: loop tail's pre_order.
2634 ciTypeFlow::Loop* ciTypeFlow::Loop::sorted_merge(Loop* lp) {
2635   Loop* leaf = this;
2636   Loop* prev = nullptr;
2637   Loop* current = leaf;
2638   while (lp != nullptr) {
2639     int lp_pre_order = lp->head()->pre_order();
2640     // Find insertion point for "lp"
2641     while (current != nullptr) {
2642       if (current == lp) {
2643         return leaf; // Already in list
2644       }
2645       if (at_insertion_point(lp, current)) {
2646         break;
2647       }
2648       prev = current;
2649       current = current->parent();
2650     }
2651     Loop* next_lp = lp->parent(); // Save future list of items to insert
2652     // Insert lp before current
2653     lp->set_parent(current);
2654     if (prev != nullptr) {
2655       prev->set_parent(lp);
2656     } else {
2657       leaf = lp;
2658     }
2659     prev = lp;     // Inserted item is new prev[ious]
2660     lp = next_lp;  // Next item to insert
2661   }
2662   return leaf;
2663 }
2664 
2665 // ------------------------------------------------------------------
2666 // ciTypeFlow::build_loop_tree
2667 //
2668 // Incrementally build loop tree.
2669 void ciTypeFlow::build_loop_tree(Block* blk) {
2670   assert(!blk->is_post_visited(), "precondition");
2671   Loop* innermost = nullptr; // merge of loop tree branches over all successors
2672 
2673   for (SuccIter iter(blk); !iter.done(); iter.next()) {
2674     Loop*  lp   = nullptr;
2675     Block* succ = iter.succ();
2676     if (!succ->is_post_visited()) {
2677       // Found backedge since predecessor post visited, but successor is not
2678       assert(succ->pre_order() <= blk->pre_order(), "should be backedge");
2679 
2680       // Create a LoopNode to mark this loop.
2681       lp = new (arena()) Loop(succ, blk);
2682       if (succ->loop() == nullptr)
2683         succ->set_loop(lp);
2684       // succ->loop will be updated to innermost loop on a later call, when blk==succ
2685 
2686     } else {  // Nested loop
2687       lp = succ->loop();
2688 
2689       // If succ is loop head, find outer loop.
2690       while (lp != nullptr && lp->head() == succ) {
2691         lp = lp->parent();
2692       }
2693       if (lp == nullptr) {
2694         // Infinite loop, it's parent is the root
2695         lp = loop_tree_root();
2696       }
2697     }
2698 
2699     // Check for irreducible loop.
2700     // Successor has already been visited. If the successor's loop head
2701     // has already been post-visited, then this is another entry into the loop.
2702     while (lp->head()->is_post_visited() && lp != loop_tree_root()) {
2703       _has_irreducible_entry = true;
2704       lp->set_irreducible(succ);
2705       if (!succ->is_on_work_list()) {
2706         // Assume irreducible entries need more data flow
2707         add_to_work_list(succ);
2708       }
2709       Loop* plp = lp->parent();
2710       if (plp == nullptr) {
2711         // This only happens for some irreducible cases.  The parent
2712         // will be updated during a later pass.
2713         break;
2714       }
2715       lp = plp;
2716     }
2717 
2718     // Merge loop tree branch for all successors.
2719     innermost = innermost == nullptr ? lp : innermost->sorted_merge(lp);
2720 
2721   } // end loop
2722 
2723   if (innermost == nullptr) {
2724     assert(blk->successors()->length() == 0, "CFG exit");
2725     blk->set_loop(loop_tree_root());
2726   } else if (innermost->head() == blk) {
2727     // If loop header, complete the tree pointers
2728     if (blk->loop() != innermost) {
2729 #ifdef ASSERT
2730       assert(blk->loop()->head() == innermost->head(), "same head");
2731       Loop* dl;
2732       for (dl = innermost; dl != nullptr && dl != blk->loop(); dl = dl->parent());
2733       assert(dl == blk->loop(), "blk->loop() already in innermost list");
2734 #endif
2735       blk->set_loop(innermost);
2736     }
2737     innermost->def_locals()->add(blk->def_locals());
2738     Loop* l = innermost;
2739     Loop* p = l->parent();
2740     while (p && l->head() == blk) {
2741       l->set_sibling(p->child());  // Put self on parents 'next child'
2742       p->set_child(l);             // Make self the first child of parent
2743       p->def_locals()->add(l->def_locals());
2744       l = p;                       // Walk up the parent chain
2745       p = l->parent();
2746     }
2747   } else {
2748     blk->set_loop(innermost);
2749     innermost->def_locals()->add(blk->def_locals());
2750   }
2751 }
2752 
2753 // ------------------------------------------------------------------
2754 // ciTypeFlow::Loop::contains
2755 //
2756 // Returns true if lp is nested loop.
2757 bool ciTypeFlow::Loop::contains(ciTypeFlow::Loop* lp) const {
2758   assert(lp != nullptr, "");
2759   if (this == lp || head() == lp->head()) return true;
2760   int depth1 = depth();
2761   int depth2 = lp->depth();
2762   if (depth1 > depth2)
2763     return false;
2764   while (depth1 < depth2) {
2765     depth2--;
2766     lp = lp->parent();
2767   }
2768   return this == lp;
2769 }
2770 
2771 // ------------------------------------------------------------------
2772 // ciTypeFlow::Loop::depth
2773 //
2774 // Loop depth
2775 int ciTypeFlow::Loop::depth() const {
2776   int dp = 0;
2777   for (Loop* lp = this->parent(); lp != nullptr; lp = lp->parent())
2778     dp++;
2779   return dp;
2780 }
2781 
2782 #ifndef PRODUCT
2783 // ------------------------------------------------------------------
2784 // ciTypeFlow::Loop::print
2785 void ciTypeFlow::Loop::print(outputStream* st, int indent) const {
2786   for (int i = 0; i < indent; i++) st->print(" ");
2787   st->print("%d<-%d %s",
2788             is_root() ? 0 : this->head()->pre_order(),
2789             is_root() ? 0 : this->tail()->pre_order(),
2790             is_irreducible()?" irr":"");
2791   st->print(" defs: ");
2792   def_locals()->print_on(st, _head->outer()->method()->max_locals());
2793   st->cr();
2794   for (Loop* ch = child(); ch != nullptr; ch = ch->sibling())
2795     ch->print(st, indent+2);
2796 }
2797 #endif
2798 
2799 // ------------------------------------------------------------------
2800 // ciTypeFlow::df_flow_types
2801 //
2802 // Perform the depth first type flow analysis. Helper for flow_types.
2803 void ciTypeFlow::df_flow_types(Block* start,
2804                                bool do_flow,
2805                                StateVector* temp_vector,
2806                                JsrSet* temp_set) {
2807   int dft_len = 100;
2808   GrowableArray<Block*> stk(dft_len);
2809 
2810   ciBlock* dummy = _method->get_method_blocks()->make_dummy_block();
2811   JsrSet* root_set = new JsrSet(0);
2812   Block* root_head = new (arena()) Block(this, dummy, root_set);
2813   Block* root_tail = new (arena()) Block(this, dummy, root_set);
2814   root_head->set_pre_order(0);
2815   root_head->set_post_order(0);
2816   root_tail->set_pre_order(max_jint);
2817   root_tail->set_post_order(max_jint);
2818   set_loop_tree_root(new (arena()) Loop(root_head, root_tail));
2819 
2820   stk.push(start);
2821 
2822   _next_pre_order = 0;  // initialize pre_order counter
2823   _rpo_list = nullptr;
2824   int next_po = 0;      // initialize post_order counter
2825 
2826   // Compute RPO and the control flow graph
2827   int size;
2828   while ((size = stk.length()) > 0) {
2829     Block* blk = stk.top(); // Leave node on stack
2830     if (!blk->is_visited()) {
2831       // forward arc in graph
2832       assert (!blk->has_pre_order(), "");
2833       blk->set_next_pre_order();
2834 
2835       if (_next_pre_order >= (int)Compile::current()->max_node_limit() / 2) {
2836         // Too many basic blocks.  Bail out.
2837         // This can happen when try/finally constructs are nested to depth N,
2838         // and there is O(2**N) cloning of jsr bodies.  See bug 4697245!
2839         // "MaxNodeLimit / 2" is used because probably the parser will
2840         // generate at least twice that many nodes and bail out.
2841         record_failure("too many basic blocks");
2842         return;
2843       }
2844       if (do_flow) {
2845         flow_block(blk, temp_vector, temp_set);
2846         if (failing()) return; // Watch for bailouts.
2847       }
2848     } else if (!blk->is_post_visited()) {
2849       // cross or back arc
2850       for (SuccIter iter(blk); !iter.done(); iter.next()) {
2851         Block* succ = iter.succ();
2852         if (!succ->is_visited()) {
2853           stk.push(succ);
2854         }
2855       }
2856       if (stk.length() == size) {
2857         // There were no additional children, post visit node now
2858         stk.pop(); // Remove node from stack
2859 
2860         build_loop_tree(blk);
2861         blk->set_post_order(next_po++);   // Assign post order
2862         prepend_to_rpo_list(blk);
2863         assert(blk->is_post_visited(), "");
2864 
2865         if (blk->is_loop_head() && !blk->is_on_work_list()) {
2866           // Assume loop heads need more data flow
2867           add_to_work_list(blk);
2868         }
2869       }
2870     } else {
2871       stk.pop(); // Remove post-visited node from stack
2872     }
2873   }
2874 }
2875 
2876 // ------------------------------------------------------------------
2877 // ciTypeFlow::flow_types
2878 //
2879 // Perform the type flow analysis, creating and cloning Blocks as
2880 // necessary.
2881 void ciTypeFlow::flow_types() {
2882   ResourceMark rm;
2883   StateVector* temp_vector = new StateVector(this);
2884   JsrSet* temp_set = new JsrSet(4);
2885 
2886   // Create the method entry block.
2887   Block* start = block_at(start_bci(), temp_set);
2888 
2889   // Load the initial state into it.
2890   const StateVector* start_state = get_start_state();
2891   if (failing())  return;
2892   start->meet(start_state);
2893 
2894   // Depth first visit
2895   df_flow_types(start, true /*do flow*/, temp_vector, temp_set);
2896 
2897   if (failing())  return;
2898   assert(_rpo_list == start, "must be start");
2899 
2900   // Any loops found?
2901   if (loop_tree_root()->child() != nullptr &&
2902       env()->comp_level() >= CompLevel_full_optimization) {
2903       // Loop optimizations are not performed on Tier1 compiles.
2904 
2905     bool changed = clone_loop_heads(temp_vector, temp_set);
2906 
2907     // If some loop heads were cloned, recompute postorder and loop tree
2908     if (changed) {
2909       loop_tree_root()->set_child(nullptr);
2910       for (Block* blk = _rpo_list; blk != nullptr;) {
2911         Block* next = blk->rpo_next();
2912         blk->df_init();
2913         blk = next;
2914       }
2915       df_flow_types(start, false /*no flow*/, temp_vector, temp_set);
2916     }
2917   }
2918 
2919   if (CITraceTypeFlow) {
2920     tty->print_cr("\nLoop tree");
2921     loop_tree_root()->print();
2922   }
2923 
2924   // Continue flow analysis until fixed point reached
2925 
2926   debug_only(int max_block = _next_pre_order;)
2927 
2928   while (!work_list_empty()) {
2929     Block* blk = work_list_next();
2930     assert (blk->has_post_order(), "post order assigned above");
2931 
2932     flow_block(blk, temp_vector, temp_set);
2933 
2934     assert (max_block == _next_pre_order, "no new blocks");
2935     assert (!failing(), "no more bailouts");
2936   }
2937 }
2938 
2939 // ------------------------------------------------------------------
2940 // ciTypeFlow::map_blocks
2941 //
2942 // Create the block map, which indexes blocks in reverse post-order.
2943 void ciTypeFlow::map_blocks() {
2944   assert(_block_map == nullptr, "single initialization");
2945   int block_ct = _next_pre_order;
2946   _block_map = NEW_ARENA_ARRAY(arena(), Block*, block_ct);
2947   assert(block_ct == block_count(), "");
2948 
2949   Block* blk = _rpo_list;
2950   for (int m = 0; m < block_ct; m++) {
2951     int rpo = blk->rpo();
2952     assert(rpo == m, "should be sequential");
2953     _block_map[rpo] = blk;
2954     blk = blk->rpo_next();
2955   }
2956   assert(blk == nullptr, "should be done");
2957 
2958   for (int j = 0; j < block_ct; j++) {
2959     assert(_block_map[j] != nullptr, "must not drop any blocks");
2960     Block* block = _block_map[j];
2961     // Remove dead blocks from successor lists:
2962     for (int e = 0; e <= 1; e++) {
2963       GrowableArray<Block*>* l = e? block->exceptions(): block->successors();
2964       for (int k = 0; k < l->length(); k++) {
2965         Block* s = l->at(k);
2966         if (!s->has_post_order()) {
2967           if (CITraceTypeFlow) {
2968             tty->print("Removing dead %s successor of #%d: ", (e? "exceptional":  "normal"), block->pre_order());
2969             s->print_value_on(tty);
2970             tty->cr();
2971           }
2972           l->remove(s);
2973           --k;
2974         }
2975       }
2976     }
2977   }
2978 }
2979 
2980 // ------------------------------------------------------------------
2981 // ciTypeFlow::get_block_for
2982 //
2983 // Find a block with this ciBlock which has a compatible JsrSet.
2984 // If no such block exists, create it, unless the option is no_create.
2985 // If the option is create_backedge_copy, always create a fresh backedge copy.
2986 ciTypeFlow::Block* ciTypeFlow::get_block_for(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs, CreateOption option) {
2987   Arena* a = arena();
2988   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
2989   if (blocks == nullptr) {
2990     // Query only?
2991     if (option == no_create)  return nullptr;
2992 
2993     // Allocate the growable array.
2994     blocks = new (a) GrowableArray<Block*>(a, 4, 0, nullptr);
2995     _idx_to_blocklist[ciBlockIndex] = blocks;
2996   }
2997 
2998   if (option != create_backedge_copy) {
2999     int len = blocks->length();
3000     for (int i = 0; i < len; i++) {
3001       Block* block = blocks->at(i);
3002       if (!block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
3003         return block;
3004       }
3005     }
3006   }
3007 
3008   // Query only?
3009   if (option == no_create)  return nullptr;
3010 
3011   // We did not find a compatible block.  Create one.
3012   Block* new_block = new (a) Block(this, _method->get_method_blocks()->block(ciBlockIndex), jsrs);
3013   if (option == create_backedge_copy)  new_block->set_backedge_copy(true);
3014   blocks->append(new_block);
3015   return new_block;
3016 }
3017 
3018 // ------------------------------------------------------------------
3019 // ciTypeFlow::backedge_copy_count
3020 //
3021 int ciTypeFlow::backedge_copy_count(int ciBlockIndex, ciTypeFlow::JsrSet* jsrs) const {
3022   GrowableArray<Block*>* blocks = _idx_to_blocklist[ciBlockIndex];
3023 
3024   if (blocks == nullptr) {
3025     return 0;
3026   }
3027 
3028   int count = 0;
3029   int len = blocks->length();
3030   for (int i = 0; i < len; i++) {
3031     Block* block = blocks->at(i);
3032     if (block->is_backedge_copy() && block->is_compatible_with(jsrs)) {
3033       count++;
3034     }
3035   }
3036 
3037   return count;
3038 }
3039 
3040 // ------------------------------------------------------------------
3041 // ciTypeFlow::do_flow
3042 //
3043 // Perform type inference flow analysis.
3044 void ciTypeFlow::do_flow() {
3045   if (CITraceTypeFlow) {
3046     tty->print_cr("\nPerforming flow analysis on method");
3047     method()->print();
3048     if (is_osr_flow())  tty->print(" at OSR bci %d", start_bci());
3049     tty->cr();
3050     method()->print_codes();
3051   }
3052   if (CITraceTypeFlow) {
3053     tty->print_cr("Initial CI Blocks");
3054     print_on(tty);
3055   }
3056   flow_types();
3057   // Watch for bailouts.
3058   if (failing()) {
3059     return;
3060   }
3061 
3062   map_blocks();
3063 
3064   if (CIPrintTypeFlow || CITraceTypeFlow) {
3065     rpo_print_on(tty);
3066   }
3067 }
3068 
3069 // ------------------------------------------------------------------
3070 // ciTypeFlow::is_dominated_by
3071 //
3072 // Determine if the instruction at bci is dominated by the instruction at dom_bci.
3073 bool ciTypeFlow::is_dominated_by(int bci, int dom_bci) {
3074   assert(!method()->has_jsrs(), "jsrs are not supported");
3075 
3076   ResourceMark rm;
3077   JsrSet* jsrs = new ciTypeFlow::JsrSet();
3078   int        index = _method->get_method_blocks()->block_containing(bci)->index();
3079   int    dom_index = _method->get_method_blocks()->block_containing(dom_bci)->index();
3080   Block*     block = get_block_for(index, jsrs, ciTypeFlow::no_create);
3081   Block* dom_block = get_block_for(dom_index, jsrs, ciTypeFlow::no_create);
3082 
3083   // Start block dominates all other blocks
3084   if (start_block()->rpo() == dom_block->rpo()) {
3085     return true;
3086   }
3087 
3088   // Dominated[i] is true if block i is dominated by dom_block
3089   int num_blocks = block_count();
3090   bool* dominated = NEW_RESOURCE_ARRAY(bool, num_blocks);
3091   for (int i = 0; i < num_blocks; ++i) {
3092     dominated[i] = true;
3093   }
3094   dominated[start_block()->rpo()] = false;
3095 
3096   // Iterative dominator algorithm
3097   bool changed = true;
3098   while (changed) {
3099     changed = false;
3100     // Use reverse postorder iteration
3101     for (Block* blk = _rpo_list; blk != nullptr; blk = blk->rpo_next()) {
3102       if (blk->is_start()) {
3103         // Ignore start block
3104         continue;
3105       }
3106       // The block is dominated if it is the dominating block
3107       // itself or if all predecessors are dominated.
3108       int index = blk->rpo();
3109       bool dom = (index == dom_block->rpo());
3110       if (!dom) {
3111         // Check if all predecessors are dominated
3112         dom = true;
3113         for (int i = 0; i < blk->predecessors()->length(); ++i) {
3114           Block* pred = blk->predecessors()->at(i);
3115           if (!dominated[pred->rpo()]) {
3116             dom = false;
3117             break;
3118           }
3119         }
3120       }
3121       // Update dominator information
3122       if (dominated[index] != dom) {
3123         changed = true;
3124         dominated[index] = dom;
3125       }
3126     }
3127   }
3128   // block dominated by dom_block?
3129   return dominated[block->rpo()];
3130 }
3131 
3132 // ------------------------------------------------------------------
3133 // ciTypeFlow::record_failure()
3134 // The ciTypeFlow object keeps track of failure reasons separately from the ciEnv.
3135 // This is required because there is not a 1-1 relation between the ciEnv and
3136 // the TypeFlow passes within a compilation task.  For example, if the compiler
3137 // is considering inlining a method, it will request a TypeFlow.  If that fails,
3138 // the compilation as a whole may continue without the inlining.  Some TypeFlow
3139 // requests are not optional; if they fail the requestor is responsible for
3140 // copying the failure reason up to the ciEnv.  (See Parse::Parse.)
3141 void ciTypeFlow::record_failure(const char* reason) {
3142   if (env()->log() != nullptr) {
3143     env()->log()->elem("failure reason='%s' phase='typeflow'", reason);
3144   }
3145   if (_failure_reason == nullptr) {
3146     // Record the first failure reason.
3147     _failure_reason = reason;
3148   }
3149 }
3150 
3151 #ifndef PRODUCT
3152 void ciTypeFlow::print() const       { print_on(tty); }
3153 
3154 // ------------------------------------------------------------------
3155 // ciTypeFlow::print_on
3156 void ciTypeFlow::print_on(outputStream* st) const {
3157   // Walk through CI blocks
3158   st->print_cr("********************************************************");
3159   st->print   ("TypeFlow for ");
3160   method()->name()->print_symbol_on(st);
3161   int limit_bci = code_size();
3162   st->print_cr("  %d bytes", limit_bci);
3163   ciMethodBlocks* mblks = _method->get_method_blocks();
3164   ciBlock* current = nullptr;
3165   for (int bci = 0; bci < limit_bci; bci++) {
3166     ciBlock* blk = mblks->block_containing(bci);
3167     if (blk != nullptr && blk != current) {
3168       current = blk;
3169       current->print_on(st);
3170 
3171       GrowableArray<Block*>* blocks = _idx_to_blocklist[blk->index()];
3172       int num_blocks = (blocks == nullptr) ? 0 : blocks->length();
3173 
3174       if (num_blocks == 0) {
3175         st->print_cr("  No Blocks");
3176       } else {
3177         for (int i = 0; i < num_blocks; i++) {
3178           Block* block = blocks->at(i);
3179           block->print_on(st);
3180         }
3181       }
3182       st->print_cr("--------------------------------------------------------");
3183       st->cr();
3184     }
3185   }
3186   st->print_cr("********************************************************");
3187   st->cr();
3188 }
3189 
3190 void ciTypeFlow::rpo_print_on(outputStream* st) const {
3191   st->print_cr("********************************************************");
3192   st->print   ("TypeFlow for ");
3193   method()->name()->print_symbol_on(st);
3194   int limit_bci = code_size();
3195   st->print_cr("  %d bytes", limit_bci);
3196   for (Block* blk = _rpo_list; blk != nullptr; blk = blk->rpo_next()) {
3197     blk->print_on(st);
3198     st->print_cr("--------------------------------------------------------");
3199     st->cr();
3200   }
3201   st->print_cr("********************************************************");
3202   st->cr();
3203 }
3204 #endif