1 /*
   2  * Copyright (c) 1999, 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 "c1/c1_IR.hpp"
  27 #include "c1/c1_Instruction.hpp"
  28 #include "c1/c1_InstructionPrinter.hpp"
  29 #include "c1/c1_ValueStack.hpp"
  30 #include "ci/ciFlatArrayKlass.hpp"
  31 #include "ci/ciInlineKlass.hpp"
  32 #include "ci/ciObjArrayKlass.hpp"
  33 #include "ci/ciTypeArrayKlass.hpp"
  34 #include "utilities/bitMap.inline.hpp"
  35 
  36 
  37 // Implementation of Instruction
  38 
  39 
  40 int Instruction::dominator_depth() {
  41   int result = -1;
  42   if (block()) {
  43     result = block()->dominator_depth();
  44   }
  45   assert(result != -1 || this->as_Local(), "Only locals have dominator depth -1");
  46   return result;
  47 }
  48 
  49 Instruction::Condition Instruction::mirror(Condition cond) {
  50   switch (cond) {
  51     case eql: return eql;
  52     case neq: return neq;
  53     case lss: return gtr;
  54     case leq: return geq;
  55     case gtr: return lss;
  56     case geq: return leq;
  57     case aeq: return beq;
  58     case beq: return aeq;
  59   }
  60   ShouldNotReachHere();
  61   return eql;
  62 }
  63 
  64 
  65 Instruction::Condition Instruction::negate(Condition cond) {
  66   switch (cond) {
  67     case eql: return neq;
  68     case neq: return eql;
  69     case lss: return geq;
  70     case leq: return gtr;
  71     case gtr: return leq;
  72     case geq: return lss;
  73     case aeq: assert(false, "Above equal cannot be negated");
  74     case beq: assert(false, "Below equal cannot be negated");
  75   }
  76   ShouldNotReachHere();
  77   return eql;
  78 }
  79 
  80 void Instruction::update_exception_state(ValueStack* state) {
  81   if (state != nullptr && (state->kind() == ValueStack::EmptyExceptionState || state->kind() == ValueStack::ExceptionState)) {
  82     assert(state->kind() == ValueStack::EmptyExceptionState || Compilation::current()->env()->should_retain_local_variables(), "unexpected state kind");
  83     _exception_state = state;
  84   } else {
  85     _exception_state = nullptr;
  86   }
  87 }
  88 
  89 // Prev without need to have BlockBegin
  90 Instruction* Instruction::prev() {
  91   Instruction* p = nullptr;
  92   Instruction* q = block();
  93   while (q != this) {
  94     assert(q != nullptr, "this is not in the block's instruction list");
  95     p = q; q = q->next();
  96   }
  97   return p;
  98 }
  99 
 100 
 101 void Instruction::state_values_do(ValueVisitor* f) {
 102   if (state_before() != nullptr) {
 103     state_before()->values_do(f);
 104   }
 105   if (exception_state() != nullptr) {
 106     exception_state()->values_do(f);
 107   }
 108 }
 109 
 110 ciType* Instruction::exact_type() const {
 111   ciType* t = declared_type();
 112   if (t != nullptr && t->is_klass()) {
 113     return t->as_klass()->exact_klass();
 114   }
 115   return nullptr;
 116 }
 117 
 118 ciKlass* Instruction::as_loaded_klass_or_null() const {
 119   ciType* type = declared_type();
 120   if (type != nullptr && type->is_klass()) {
 121     ciKlass* klass = type->as_klass();
 122     if (klass->is_loaded()) {
 123       return klass;
 124     }
 125   }
 126   return nullptr;
 127 }
 128 
 129 bool Instruction::is_loaded_flat_array() const {
 130   if (UseFlatArray) {
 131     ciType* type = declared_type();
 132     return type != nullptr && type->is_flat_array_klass();
 133   }
 134   return false;
 135 }
 136 
 137 bool Instruction::maybe_flat_array() {
 138   if (UseFlatArray) {
 139     ciType* type = declared_type();
 140     if (type != nullptr) {
 141       if (type->is_obj_array_klass()) {
 142         // TODO 8325106 Fix comment
 143         // The runtime type of [LMyValue might be [QMyValue due to [QMyValue <: [LMyValue.
 144         ciKlass* element_klass = type->as_obj_array_klass()->element_klass();
 145         if (element_klass->can_be_inline_klass() && (!element_klass->is_inlinetype() || element_klass->as_inline_klass()->flat_in_array())) {
 146           return true;
 147         }
 148       } else if (type->is_flat_array_klass()) {
 149         return true;
 150       } else if (type->is_klass() && type->as_klass()->is_java_lang_Object()) {
 151         // This can happen as a parameter to System.arraycopy()
 152         return true;
 153       }
 154     } else {
 155       // Type info gets lost during Phi merging (Phi, IfOp, etc), but we might be storing into a
 156       // flat array, so we should do a runtime check.
 157       return true;
 158     }
 159   }
 160   return false;
 161 }
 162 
 163 bool Instruction::maybe_null_free_array() {
 164   ciType* type = declared_type();
 165   if (type != nullptr) {
 166     if (type->is_obj_array_klass()) {
 167       // Due to array covariance, the runtime type might be a null-free array.
 168       if (type->as_obj_array_klass()->can_be_inline_array_klass()) {
 169         return true;
 170       }
 171     }
 172   } else {
 173     // Type info gets lost during Phi merging (Phi, IfOp, etc), but we might be storing into a
 174     // null-free array, so we should do a runtime check.
 175     return true;
 176   }
 177   return false;
 178 }
 179 
 180 #ifndef PRODUCT
 181 void Instruction::check_state(ValueStack* state) {
 182   if (state != nullptr) {
 183     state->verify();
 184   }
 185 }
 186 
 187 
 188 void Instruction::print() {
 189   InstructionPrinter ip;
 190   print(ip);
 191 }
 192 
 193 
 194 void Instruction::print_line() {
 195   InstructionPrinter ip;
 196   ip.print_line(this);
 197 }
 198 
 199 
 200 void Instruction::print(InstructionPrinter& ip) {
 201   ip.print_head();
 202   ip.print_line(this);
 203   tty->cr();
 204 }
 205 #endif // PRODUCT
 206 
 207 
 208 // perform constant and interval tests on index value
 209 bool AccessIndexed::compute_needs_range_check() {
 210   if (length()) {
 211     Constant* clength = length()->as_Constant();
 212     Constant* cindex = index()->as_Constant();
 213     if (clength && cindex) {
 214       IntConstant* l = clength->type()->as_IntConstant();
 215       IntConstant* i = cindex->type()->as_IntConstant();
 216       if (l && i && i->value() < l->value() && i->value() >= 0) {
 217         return false;
 218       }
 219     }
 220   }
 221 
 222   if (!this->check_flag(NeedsRangeCheckFlag)) {
 223     return false;
 224   }
 225 
 226   return true;
 227 }
 228 
 229 
 230 ciType* Constant::exact_type() const {
 231   if (type()->is_object() && type()->as_ObjectType()->is_loaded()) {
 232     return type()->as_ObjectType()->exact_type();
 233   }
 234   return nullptr;
 235 }
 236 
 237 ciType* LoadIndexed::exact_type() const {
 238   ciType* array_type = array()->exact_type();
 239   if (delayed() == nullptr && array_type != nullptr) {
 240     assert(array_type->is_array_klass(), "what else?");
 241     ciArrayKlass* ak = (ciArrayKlass*)array_type;
 242 
 243     if (ak->element_type()->is_instance_klass()) {
 244       ciInstanceKlass* ik = (ciInstanceKlass*)ak->element_type();
 245       if (ik->is_loaded() && ik->is_final()) {
 246         return ik;
 247       }
 248     }
 249   }
 250   return Instruction::exact_type();
 251 }
 252 
 253 ciType* LoadIndexed::declared_type() const {
 254   if (delayed() != nullptr) {
 255     return delayed()->field()->type();
 256   }
 257   ciType* array_type = array()->declared_type();
 258   if (array_type == nullptr || !array_type->is_loaded()) {
 259     return nullptr;
 260   }
 261   assert(array_type->is_array_klass(), "what else?");
 262   ciArrayKlass* ak = (ciArrayKlass*)array_type;
 263   return ak->element_type();
 264 }
 265 
 266 bool StoreIndexed::is_exact_flat_array_store() const {
 267   if (array()->is_loaded_flat_array() && value()->as_Constant() == nullptr && value()->declared_type() != nullptr) {
 268     ciKlass* element_klass = array()->declared_type()->as_flat_array_klass()->element_klass();
 269     ciKlass* actual_klass = value()->declared_type()->as_klass();
 270 
 271     // The following check can fail with inlining:
 272     //     void test45_inline(Object[] oa, Object o, int index) { oa[index] = o; }
 273     //     void test45(MyValue1[] va, int index, MyValue2 v) { test45_inline(va, v, index); }
 274     if (element_klass == actual_klass) {
 275       return true;
 276     }
 277   }
 278   return false;
 279 }
 280 
 281 ciType* LoadField::declared_type() const {
 282   return field()->type();
 283 }
 284 
 285 
 286 ciType* NewTypeArray::exact_type() const {
 287   return ciTypeArrayKlass::make(elt_type());
 288 }
 289 
 290 ciType* NewObjectArray::exact_type() const {
 291   return ciArrayKlass::make(klass());
 292 }
 293 
 294 ciType* NewMultiArray::exact_type() const {
 295   return _klass;
 296 }
 297 
 298 ciType* NewArray::declared_type() const {
 299   return exact_type();
 300 }
 301 
 302 ciType* NewInstance::exact_type() const {
 303   return klass();
 304 }
 305 
 306 ciType* NewInstance::declared_type() const {
 307   return exact_type();
 308 }
 309 
 310 ciType* CheckCast::declared_type() const {
 311   return klass();
 312 }
 313 
 314 // Implementation of ArithmeticOp
 315 
 316 bool ArithmeticOp::is_commutative() const {
 317   switch (op()) {
 318     case Bytecodes::_iadd: // fall through
 319     case Bytecodes::_ladd: // fall through
 320     case Bytecodes::_fadd: // fall through
 321     case Bytecodes::_dadd: // fall through
 322     case Bytecodes::_imul: // fall through
 323     case Bytecodes::_lmul: // fall through
 324     case Bytecodes::_fmul: // fall through
 325     case Bytecodes::_dmul: return true;
 326     default              : return false;
 327   }
 328 }
 329 
 330 
 331 bool ArithmeticOp::can_trap() const {
 332   switch (op()) {
 333     case Bytecodes::_idiv: // fall through
 334     case Bytecodes::_ldiv: // fall through
 335     case Bytecodes::_irem: // fall through
 336     case Bytecodes::_lrem: return true;
 337     default              : return false;
 338   }
 339 }
 340 
 341 
 342 // Implementation of LogicOp
 343 
 344 bool LogicOp::is_commutative() const {
 345 #ifdef ASSERT
 346   switch (op()) {
 347     case Bytecodes::_iand: // fall through
 348     case Bytecodes::_land: // fall through
 349     case Bytecodes::_ior : // fall through
 350     case Bytecodes::_lor : // fall through
 351     case Bytecodes::_ixor: // fall through
 352     case Bytecodes::_lxor: break;
 353     default              : ShouldNotReachHere(); break;
 354   }
 355 #endif
 356   // all LogicOps are commutative
 357   return true;
 358 }
 359 
 360 
 361 // Implementation of IfOp
 362 
 363 bool IfOp::is_commutative() const {
 364   return cond() == eql || cond() == neq;
 365 }
 366 
 367 
 368 // Implementation of StateSplit
 369 
 370 void StateSplit::substitute(BlockList& list, BlockBegin* old_block, BlockBegin* new_block) {
 371   NOT_PRODUCT(bool assigned = false;)
 372   for (int i = 0; i < list.length(); i++) {
 373     BlockBegin** b = list.adr_at(i);
 374     if (*b == old_block) {
 375       *b = new_block;
 376       NOT_PRODUCT(assigned = true;)
 377     }
 378   }
 379   assert(assigned == true, "should have assigned at least once");
 380 }
 381 
 382 
 383 IRScope* StateSplit::scope() const {
 384   return _state->scope();
 385 }
 386 
 387 
 388 void StateSplit::state_values_do(ValueVisitor* f) {
 389   Instruction::state_values_do(f);
 390   if (state() != nullptr) state()->values_do(f);
 391 }
 392 
 393 
 394 void BlockBegin::state_values_do(ValueVisitor* f) {
 395   StateSplit::state_values_do(f);
 396 
 397   if (is_set(BlockBegin::exception_entry_flag)) {
 398     for (int i = 0; i < number_of_exception_states(); i++) {
 399       exception_state_at(i)->values_do(f);
 400     }
 401   }
 402 }
 403 
 404 
 405 StoreField::StoreField(Value obj, int offset, ciField* field, Value value, bool is_static,
 406                        ValueStack* state_before, bool needs_patching)
 407   : AccessField(obj, offset, field, is_static, state_before, needs_patching)
 408   , _value(value)
 409   , _enclosing_field(nullptr)
 410 {
 411   set_flag(NeedsWriteBarrierFlag, as_ValueType(field_type())->is_object());
 412 #ifdef ASSERT
 413   AssertValues assert_value;
 414   values_do(&assert_value);
 415 #endif
 416   pin();
 417 }
 418 
 419 StoreIndexed::StoreIndexed(Value array, Value index, Value length, BasicType elt_type, Value value,
 420                            ValueStack* state_before, bool check_boolean, bool mismatched)
 421   : AccessIndexed(array, index, length, elt_type, state_before, mismatched)
 422   , _value(value), _check_boolean(check_boolean)
 423 {
 424   set_flag(NeedsWriteBarrierFlag, (as_ValueType(elt_type)->is_object()));
 425   set_flag(NeedsStoreCheckFlag, (as_ValueType(elt_type)->is_object()));
 426 #ifdef ASSERT
 427   AssertValues assert_value;
 428   values_do(&assert_value);
 429 #endif
 430   pin();
 431 }
 432 
 433 
 434 // Implementation of Invoke
 435 
 436 
 437 Invoke::Invoke(Bytecodes::Code code, ValueType* result_type, Value recv, Values* args,
 438                ciMethod* target, ValueStack* state_before)
 439   : StateSplit(result_type, state_before)
 440   , _code(code)
 441   , _recv(recv)
 442   , _args(args)
 443   , _target(target)
 444 {
 445   set_flag(TargetIsLoadedFlag,   target->is_loaded());
 446   set_flag(TargetIsFinalFlag,    target_is_loaded() && target->is_final_method());
 447 
 448   assert(args != nullptr, "args must exist");
 449 #ifdef ASSERT
 450   AssertValues assert_value;
 451   values_do(&assert_value);
 452 #endif
 453 
 454   // provide an initial guess of signature size.
 455   _signature = new BasicTypeList(number_of_arguments() + (has_receiver() ? 1 : 0));
 456   if (has_receiver()) {
 457     _signature->append(as_BasicType(receiver()->type()));
 458   }
 459   for (int i = 0; i < number_of_arguments(); i++) {
 460     Value v = argument_at(i);
 461     ValueType* t = v->type();
 462     BasicType bt = as_BasicType(t);
 463     _signature->append(bt);
 464   }
 465 }
 466 
 467 
 468 void Invoke::state_values_do(ValueVisitor* f) {
 469   StateSplit::state_values_do(f);
 470   if (state_before() != nullptr) state_before()->values_do(f);
 471   if (state()        != nullptr) state()->values_do(f);
 472 }
 473 
 474 ciType* Invoke::declared_type() const {
 475   ciSignature* declared_signature = state()->scope()->method()->get_declared_signature_at_bci(state()->bci());
 476   ciType *t = declared_signature->return_type();
 477   assert(t->basic_type() != T_VOID, "need return value of void method?");
 478   return t;
 479 }
 480 
 481 // Implementation of Constant
 482 intx Constant::hash() const {
 483   if (state_before() == nullptr) {
 484     switch (type()->tag()) {
 485     case intTag:
 486       return HASH2(name(), type()->as_IntConstant()->value());
 487     case addressTag:
 488       return HASH2(name(), type()->as_AddressConstant()->value());
 489     case longTag:
 490       {
 491         jlong temp = type()->as_LongConstant()->value();
 492         return HASH3(name(), high(temp), low(temp));
 493       }
 494     case floatTag:
 495       return HASH2(name(), jint_cast(type()->as_FloatConstant()->value()));
 496     case doubleTag:
 497       {
 498         jlong temp = jlong_cast(type()->as_DoubleConstant()->value());
 499         return HASH3(name(), high(temp), low(temp));
 500       }
 501     case objectTag:
 502       assert(type()->as_ObjectType()->is_loaded(), "can't handle unloaded values");
 503       return HASH2(name(), type()->as_ObjectType()->constant_value());
 504     case metaDataTag:
 505       assert(type()->as_MetadataType()->is_loaded(), "can't handle unloaded values");
 506       return HASH2(name(), type()->as_MetadataType()->constant_value());
 507     default:
 508       ShouldNotReachHere();
 509     }
 510   }
 511   return 0;
 512 }
 513 
 514 bool Constant::is_equal(Value v) const {
 515   if (v->as_Constant() == nullptr) return false;
 516 
 517   switch (type()->tag()) {
 518     case intTag:
 519       {
 520         IntConstant* t1 =    type()->as_IntConstant();
 521         IntConstant* t2 = v->type()->as_IntConstant();
 522         return (t1 != nullptr && t2 != nullptr &&
 523                 t1->value() == t2->value());
 524       }
 525     case longTag:
 526       {
 527         LongConstant* t1 =    type()->as_LongConstant();
 528         LongConstant* t2 = v->type()->as_LongConstant();
 529         return (t1 != nullptr && t2 != nullptr &&
 530                 t1->value() == t2->value());
 531       }
 532     case floatTag:
 533       {
 534         FloatConstant* t1 =    type()->as_FloatConstant();
 535         FloatConstant* t2 = v->type()->as_FloatConstant();
 536         return (t1 != nullptr && t2 != nullptr &&
 537                 jint_cast(t1->value()) == jint_cast(t2->value()));
 538       }
 539     case doubleTag:
 540       {
 541         DoubleConstant* t1 =    type()->as_DoubleConstant();
 542         DoubleConstant* t2 = v->type()->as_DoubleConstant();
 543         return (t1 != nullptr && t2 != nullptr &&
 544                 jlong_cast(t1->value()) == jlong_cast(t2->value()));
 545       }
 546     case objectTag:
 547       {
 548         ObjectType* t1 =    type()->as_ObjectType();
 549         ObjectType* t2 = v->type()->as_ObjectType();
 550         return (t1 != nullptr && t2 != nullptr &&
 551                 t1->is_loaded() && t2->is_loaded() &&
 552                 t1->constant_value() == t2->constant_value());
 553       }
 554     case metaDataTag:
 555       {
 556         MetadataType* t1 =    type()->as_MetadataType();
 557         MetadataType* t2 = v->type()->as_MetadataType();
 558         return (t1 != nullptr && t2 != nullptr &&
 559                 t1->is_loaded() && t2->is_loaded() &&
 560                 t1->constant_value() == t2->constant_value());
 561       }
 562     default:
 563       return false;
 564   }
 565 }
 566 
 567 Constant::CompareResult Constant::compare(Instruction::Condition cond, Value right) const {
 568   Constant* rc = right->as_Constant();
 569   // other is not a constant
 570   if (rc == nullptr) return not_comparable;
 571 
 572   ValueType* lt = type();
 573   ValueType* rt = rc->type();
 574   // different types
 575   if (lt->base() != rt->base()) return not_comparable;
 576   switch (lt->tag()) {
 577   case intTag: {
 578     int x = lt->as_IntConstant()->value();
 579     int y = rt->as_IntConstant()->value();
 580     switch (cond) {
 581     case If::eql: return x == y ? cond_true : cond_false;
 582     case If::neq: return x != y ? cond_true : cond_false;
 583     case If::lss: return x <  y ? cond_true : cond_false;
 584     case If::leq: return x <= y ? cond_true : cond_false;
 585     case If::gtr: return x >  y ? cond_true : cond_false;
 586     case If::geq: return x >= y ? cond_true : cond_false;
 587     default     : break;
 588     }
 589     break;
 590   }
 591   case longTag: {
 592     jlong x = lt->as_LongConstant()->value();
 593     jlong y = rt->as_LongConstant()->value();
 594     switch (cond) {
 595     case If::eql: return x == y ? cond_true : cond_false;
 596     case If::neq: return x != y ? cond_true : cond_false;
 597     case If::lss: return x <  y ? cond_true : cond_false;
 598     case If::leq: return x <= y ? cond_true : cond_false;
 599     case If::gtr: return x >  y ? cond_true : cond_false;
 600     case If::geq: return x >= y ? cond_true : cond_false;
 601     default     : break;
 602     }
 603     break;
 604   }
 605   case objectTag: {
 606     ciObject* xvalue = lt->as_ObjectType()->constant_value();
 607     ciObject* yvalue = rt->as_ObjectType()->constant_value();
 608     assert(xvalue != nullptr && yvalue != nullptr, "not constants");
 609     if (xvalue->is_loaded() && yvalue->is_loaded()) {
 610       switch (cond) {
 611       case If::eql: return xvalue == yvalue ? cond_true : cond_false;
 612       case If::neq: return xvalue != yvalue ? cond_true : cond_false;
 613       default     : break;
 614       }
 615     }
 616     break;
 617   }
 618   case metaDataTag: {
 619     ciMetadata* xvalue = lt->as_MetadataType()->constant_value();
 620     ciMetadata* yvalue = rt->as_MetadataType()->constant_value();
 621     assert(xvalue != nullptr && yvalue != nullptr, "not constants");
 622     if (xvalue->is_loaded() && yvalue->is_loaded()) {
 623       switch (cond) {
 624       case If::eql: return xvalue == yvalue ? cond_true : cond_false;
 625       case If::neq: return xvalue != yvalue ? cond_true : cond_false;
 626       default     : break;
 627       }
 628     }
 629     break;
 630   }
 631   default:
 632     break;
 633   }
 634   return not_comparable;
 635 }
 636 
 637 
 638 // Implementation of BlockBegin
 639 
 640 void BlockBegin::set_end(BlockEnd* new_end) { // Assumes that no predecessor of new_end still has it as its successor
 641   assert(new_end != nullptr, "Should not reset block new_end to null");
 642   if (new_end == _end) return;
 643 
 644   // Remove this block as predecessor of its current successors
 645   if (_end != nullptr) {
 646     for (int i = 0; i < number_of_sux(); i++) {
 647       sux_at(i)->remove_predecessor(this);
 648     }
 649   }
 650 
 651   _end = new_end;
 652 
 653   // Add this block as predecessor of its new successors
 654   for (int i = 0; i < number_of_sux(); i++) {
 655     sux_at(i)->add_predecessor(this);
 656   }
 657 }
 658 
 659 
 660 void BlockBegin::disconnect_edge(BlockBegin* from, BlockBegin* to) {
 661   // disconnect any edges between from and to
 662 #ifndef PRODUCT
 663   if (PrintIR && Verbose) {
 664     tty->print_cr("Disconnected edge B%d -> B%d", from->block_id(), to->block_id());
 665   }
 666 #endif
 667   for (int s = 0; s < from->number_of_sux();) {
 668     BlockBegin* sux = from->sux_at(s);
 669     if (sux == to) {
 670       int index = sux->_predecessors.find(from);
 671       if (index >= 0) {
 672         sux->_predecessors.remove_at(index);
 673       }
 674       from->end()->remove_sux_at(s);
 675     } else {
 676       s++;
 677     }
 678   }
 679 }
 680 
 681 
 682 void BlockBegin::substitute_sux(BlockBegin* old_sux, BlockBegin* new_sux) {
 683   // modify predecessors before substituting successors
 684   for (int i = 0; i < number_of_sux(); i++) {
 685     if (sux_at(i) == old_sux) {
 686       // remove old predecessor before adding new predecessor
 687       // otherwise there is a dead predecessor in the list
 688       new_sux->remove_predecessor(old_sux);
 689       new_sux->add_predecessor(this);
 690     }
 691   }
 692   old_sux->remove_predecessor(this);
 693   end()->substitute_sux(old_sux, new_sux);
 694 }
 695 
 696 
 697 
 698 // In general it is not possible to calculate a value for the field "depth_first_number"
 699 // of the inserted block, without recomputing the values of the other blocks
 700 // in the CFG. Therefore the value of "depth_first_number" in BlockBegin becomes meaningless.
 701 BlockBegin* BlockBegin::insert_block_between(BlockBegin* sux) {
 702   int bci = sux->bci();
 703   // critical edge splitting may introduce a goto after a if and array
 704   // bound check elimination may insert a predicate between the if and
 705   // goto. The bci of the goto can't be the one of the if otherwise
 706   // the state and bci are inconsistent and a deoptimization triggered
 707   // by the predicate would lead to incorrect execution/a crash.
 708   BlockBegin* new_sux = new BlockBegin(bci);
 709 
 710   // mark this block (special treatment when block order is computed)
 711   new_sux->set(critical_edge_split_flag);
 712 
 713   // This goto is not a safepoint.
 714   Goto* e = new Goto(sux, false);
 715   new_sux->set_next(e, bci);
 716   new_sux->set_end(e);
 717   // setup states
 718   ValueStack* s = end()->state();
 719   new_sux->set_state(s->copy(s->kind(), bci));
 720   e->set_state(s->copy(s->kind(), bci));
 721   assert(new_sux->state()->locals_size() == s->locals_size(), "local size mismatch!");
 722   assert(new_sux->state()->stack_size() == s->stack_size(), "stack size mismatch!");
 723   assert(new_sux->state()->locks_size() == s->locks_size(), "locks size mismatch!");
 724 
 725   // link predecessor to new block
 726   end()->substitute_sux(sux, new_sux);
 727 
 728   // The ordering needs to be the same, so remove the link that the
 729   // set_end call above added and substitute the new_sux for this
 730   // block.
 731   sux->remove_predecessor(new_sux);
 732 
 733   // the successor could be the target of a switch so it might have
 734   // multiple copies of this predecessor, so substitute the new_sux
 735   // for the first and delete the rest.
 736   bool assigned = false;
 737   BlockList& list = sux->_predecessors;
 738   for (int i = 0; i < list.length(); i++) {
 739     BlockBegin** b = list.adr_at(i);
 740     if (*b == this) {
 741       if (assigned) {
 742         list.remove_at(i);
 743         // reprocess this index
 744         i--;
 745       } else {
 746         assigned = true;
 747         *b = new_sux;
 748       }
 749       // link the new block back to it's predecessors.
 750       new_sux->add_predecessor(this);
 751     }
 752   }
 753   assert(assigned == true, "should have assigned at least once");
 754   return new_sux;
 755 }
 756 
 757 
 758 void BlockBegin::add_predecessor(BlockBegin* pred) {
 759   _predecessors.append(pred);
 760 }
 761 
 762 
 763 void BlockBegin::remove_predecessor(BlockBegin* pred) {
 764   int idx;
 765   while ((idx = _predecessors.find(pred)) >= 0) {
 766     _predecessors.remove_at(idx);
 767   }
 768 }
 769 
 770 
 771 void BlockBegin::add_exception_handler(BlockBegin* b) {
 772   assert(b != nullptr && (b->is_set(exception_entry_flag)), "exception handler must exist");
 773   // add only if not in the list already
 774   if (!_exception_handlers.contains(b)) _exception_handlers.append(b);
 775 }
 776 
 777 int BlockBegin::add_exception_state(ValueStack* state) {
 778   assert(is_set(exception_entry_flag), "only for xhandlers");
 779   if (_exception_states == nullptr) {
 780     _exception_states = new ValueStackStack(4);
 781   }
 782   _exception_states->append(state);
 783   return _exception_states->length() - 1;
 784 }
 785 
 786 
 787 void BlockBegin::iterate_preorder(boolArray& mark, BlockClosure* closure) {
 788   if (!mark.at(block_id())) {
 789     mark.at_put(block_id(), true);
 790     closure->block_do(this);
 791     BlockEnd* e = end(); // must do this after block_do because block_do may change it!
 792     { for (int i = number_of_exception_handlers() - 1; i >= 0; i--) exception_handler_at(i)->iterate_preorder(mark, closure); }
 793     { for (int i = e->number_of_sux            () - 1; i >= 0; i--) e->sux_at           (i)->iterate_preorder(mark, closure); }
 794   }
 795 }
 796 
 797 
 798 void BlockBegin::iterate_postorder(boolArray& mark, BlockClosure* closure) {
 799   if (!mark.at(block_id())) {
 800     mark.at_put(block_id(), true);
 801     BlockEnd* e = end();
 802     { for (int i = number_of_exception_handlers() - 1; i >= 0; i--) exception_handler_at(i)->iterate_postorder(mark, closure); }
 803     { for (int i = e->number_of_sux            () - 1; i >= 0; i--) e->sux_at           (i)->iterate_postorder(mark, closure); }
 804     closure->block_do(this);
 805   }
 806 }
 807 
 808 
 809 void BlockBegin::iterate_preorder(BlockClosure* closure) {
 810   int mark_len = number_of_blocks();
 811   boolArray mark(mark_len, mark_len, false);
 812   iterate_preorder(mark, closure);
 813 }
 814 
 815 
 816 void BlockBegin::iterate_postorder(BlockClosure* closure) {
 817   int mark_len = number_of_blocks();
 818   boolArray mark(mark_len, mark_len, false);
 819   iterate_postorder(mark, closure);
 820 }
 821 
 822 
 823 void BlockBegin::block_values_do(ValueVisitor* f) {
 824   for (Instruction* n = this; n != nullptr; n = n->next()) n->values_do(f);
 825 }
 826 
 827 
 828 #ifndef PRODUCT
 829    #define TRACE_PHI(code) if (PrintPhiFunctions) { code; }
 830 #else
 831    #define TRACE_PHI(coce)
 832 #endif
 833 
 834 
 835 bool BlockBegin::try_merge(ValueStack* new_state, bool has_irreducible_loops) {
 836   TRACE_PHI(tty->print_cr("********** try_merge for block B%d", block_id()));
 837 
 838   // local variables used for state iteration
 839   int index;
 840   Value new_value, existing_value;
 841 
 842   ValueStack* existing_state = state();
 843   if (existing_state == nullptr) {
 844     TRACE_PHI(tty->print_cr("first call of try_merge for this block"));
 845 
 846     if (is_set(BlockBegin::was_visited_flag)) {
 847       // this actually happens for complicated jsr/ret structures
 848       return false; // BAILOUT in caller
 849     }
 850 
 851     // copy state because it is altered
 852     new_state = new_state->copy(ValueStack::BlockBeginState, bci());
 853 
 854     // Use method liveness to invalidate dead locals
 855     MethodLivenessResult liveness = new_state->scope()->method()->liveness_at_bci(bci());
 856     if (liveness.is_valid()) {
 857       assert((int)liveness.size() == new_state->locals_size(), "error in use of liveness");
 858 
 859       for_each_local_value(new_state, index, new_value) {
 860         if (!liveness.at(index) || new_value->type()->is_illegal()) {
 861           new_state->invalidate_local(index);
 862           TRACE_PHI(tty->print_cr("invalidating dead local %d", index));
 863         }
 864       }
 865     }
 866 
 867     if (is_set(BlockBegin::parser_loop_header_flag)) {
 868       TRACE_PHI(tty->print_cr("loop header block, initializing phi functions"));
 869 
 870       for_each_stack_value(new_state, index, new_value) {
 871         new_state->setup_phi_for_stack(this, index);
 872         TRACE_PHI(tty->print_cr("creating phi-function %c%d for stack %d", new_state->stack_at(index)->type()->tchar(), new_state->stack_at(index)->id(), index));
 873       }
 874 
 875       BitMap& requires_phi_function = new_state->scope()->requires_phi_function();
 876       for_each_local_value(new_state, index, new_value) {
 877         bool requires_phi = requires_phi_function.at(index) || (new_value->type()->is_double_word() && requires_phi_function.at(index + 1));
 878         if (requires_phi || !SelectivePhiFunctions || has_irreducible_loops) {
 879           new_state->setup_phi_for_local(this, index);
 880           TRACE_PHI(tty->print_cr("creating phi-function %c%d for local %d", new_state->local_at(index)->type()->tchar(), new_state->local_at(index)->id(), index));
 881         }
 882       }
 883     }
 884 
 885     // initialize state of block
 886     set_state(new_state);
 887 
 888   } else if (existing_state->is_same(new_state)) {
 889     TRACE_PHI(tty->print_cr("existing state found"));
 890 
 891     assert(existing_state->scope() == new_state->scope(), "not matching");
 892     assert(existing_state->locals_size() == new_state->locals_size(), "not matching");
 893     assert(existing_state->stack_size() == new_state->stack_size(), "not matching");
 894 
 895     if (is_set(BlockBegin::was_visited_flag)) {
 896       TRACE_PHI(tty->print_cr("loop header block, phis must be present"));
 897 
 898       if (!is_set(BlockBegin::parser_loop_header_flag)) {
 899         // this actually happens for complicated jsr/ret structures
 900         return false; // BAILOUT in caller
 901       }
 902 
 903       for_each_local_value(existing_state, index, existing_value) {
 904         Value new_value = new_state->local_at(index);
 905         if (new_value == nullptr || new_value->type()->tag() != existing_value->type()->tag()) {
 906           Phi* existing_phi = existing_value->as_Phi();
 907           if (existing_phi == nullptr) {
 908             return false; // BAILOUT in caller
 909           }
 910           // Invalidate the phi function here. This case is very rare except for
 911           // JVMTI capability "can_access_local_variables".
 912           // In really rare cases we will bail out in LIRGenerator::move_to_phi.
 913           existing_phi->make_illegal();
 914           existing_state->invalidate_local(index);
 915           TRACE_PHI(tty->print_cr("invalidating local %d because of type mismatch", index));
 916         }
 917 
 918         if (existing_value != new_state->local_at(index) && existing_value->as_Phi() == nullptr) {
 919           TRACE_PHI(tty->print_cr("required phi for local %d is missing, irreducible loop?", index));
 920           return false; // BAILOUT in caller
 921         }
 922       }
 923 
 924 #ifdef ASSERT
 925       // check that all necessary phi functions are present
 926       for_each_stack_value(existing_state, index, existing_value) {
 927         assert(existing_value->as_Phi() != nullptr && existing_value->as_Phi()->block() == this, "phi function required");
 928       }
 929       for_each_local_value(existing_state, index, existing_value) {
 930         assert(existing_value == new_state->local_at(index) || (existing_value->as_Phi() != nullptr && existing_value->as_Phi()->as_Phi()->block() == this), "phi function required");
 931       }
 932 #endif
 933 
 934     } else {
 935       TRACE_PHI(tty->print_cr("creating phi functions on demand"));
 936 
 937       // create necessary phi functions for stack
 938       for_each_stack_value(existing_state, index, existing_value) {
 939         Value new_value = new_state->stack_at(index);
 940         Phi* existing_phi = existing_value->as_Phi();
 941 
 942         if (new_value != existing_value && (existing_phi == nullptr || existing_phi->block() != this)) {
 943           existing_state->setup_phi_for_stack(this, index);
 944           TRACE_PHI(tty->print_cr("creating phi-function %c%d for stack %d", existing_state->stack_at(index)->type()->tchar(), existing_state->stack_at(index)->id(), index));
 945         }
 946       }
 947 
 948       // create necessary phi functions for locals
 949       for_each_local_value(existing_state, index, existing_value) {
 950         Value new_value = new_state->local_at(index);
 951         Phi* existing_phi = existing_value->as_Phi();
 952 
 953         if (new_value == nullptr || new_value->type()->tag() != existing_value->type()->tag()) {
 954           existing_state->invalidate_local(index);
 955           TRACE_PHI(tty->print_cr("invalidating local %d because of type mismatch", index));
 956         } else if (new_value != existing_value && (existing_phi == nullptr || existing_phi->block() != this)) {
 957           existing_state->setup_phi_for_local(this, index);
 958           TRACE_PHI(tty->print_cr("creating phi-function %c%d for local %d", existing_state->local_at(index)->type()->tchar(), existing_state->local_at(index)->id(), index));
 959         }
 960       }
 961     }
 962 
 963     assert(existing_state->caller_state() == new_state->caller_state(), "caller states must be equal");
 964 
 965   } else {
 966     assert(false, "stack or locks not matching (invalid bytecodes)");
 967     return false;
 968   }
 969 
 970   TRACE_PHI(tty->print_cr("********** try_merge for block B%d successful", block_id()));
 971 
 972   return true;
 973 }
 974 
 975 
 976 #ifndef PRODUCT
 977 void BlockBegin::print_block() {
 978   InstructionPrinter ip;
 979   print_block(ip, false);
 980 }
 981 
 982 
 983 void BlockBegin::print_block(InstructionPrinter& ip, bool live_only) {
 984   ip.print_instr(this); tty->cr();
 985   ip.print_stack(this->state()); tty->cr();
 986   ip.print_inline_level(this);
 987   ip.print_head();
 988   for (Instruction* n = next(); n != nullptr; n = n->next()) {
 989     if (!live_only || n->is_pinned() || n->use_count() > 0) {
 990       ip.print_line(n);
 991     }
 992   }
 993   tty->cr();
 994 }
 995 #endif // PRODUCT
 996 
 997 
 998 // Implementation of BlockList
 999 
1000 void BlockList::iterate_forward (BlockClosure* closure) {
1001   const int l = length();
1002   for (int i = 0; i < l; i++) closure->block_do(at(i));
1003 }
1004 
1005 
1006 void BlockList::iterate_backward(BlockClosure* closure) {
1007   for (int i = length() - 1; i >= 0; i--) closure->block_do(at(i));
1008 }
1009 
1010 
1011 void BlockList::values_do(ValueVisitor* f) {
1012   for (int i = length() - 1; i >= 0; i--) at(i)->block_values_do(f);
1013 }
1014 
1015 
1016 #ifndef PRODUCT
1017 void BlockList::print(bool cfg_only, bool live_only) {
1018   InstructionPrinter ip;
1019   for (int i = 0; i < length(); i++) {
1020     BlockBegin* block = at(i);
1021     if (cfg_only) {
1022       ip.print_instr(block); tty->cr();
1023     } else {
1024       block->print_block(ip, live_only);
1025     }
1026   }
1027 }
1028 #endif // PRODUCT
1029 
1030 
1031 // Implementation of BlockEnd
1032 
1033 void BlockEnd::substitute_sux(BlockBegin* old_sux, BlockBegin* new_sux) {
1034   substitute(*_sux, old_sux, new_sux);
1035 }
1036 
1037 // Implementation of Phi
1038 
1039 // Normal phi functions take their operands from the last instruction of the
1040 // predecessor. Special handling is needed for xhanlder entries because there
1041 // the state of arbitrary instructions are needed.
1042 
1043 Value Phi::operand_at(int i) const {
1044   ValueStack* state;
1045   if (_block->is_set(BlockBegin::exception_entry_flag)) {
1046     state = _block->exception_state_at(i);
1047   } else {
1048     state = _block->pred_at(i)->end()->state();
1049   }
1050   assert(state != nullptr, "");
1051 
1052   if (is_local()) {
1053     return state->local_at(local_index());
1054   } else {
1055     return state->stack_at(stack_index());
1056   }
1057 }
1058 
1059 
1060 int Phi::operand_count() const {
1061   if (_block->is_set(BlockBegin::exception_entry_flag)) {
1062     return _block->number_of_exception_states();
1063   } else {
1064     return _block->number_of_preds();
1065   }
1066 }
1067 
1068 #ifdef ASSERT
1069 // Constructor of Assert
1070 Assert::Assert(Value x, Condition cond, bool unordered_is_true, Value y) : Instruction(illegalType)
1071   , _x(x)
1072   , _cond(cond)
1073   , _y(y)
1074 {
1075   set_flag(UnorderedIsTrueFlag, unordered_is_true);
1076   assert(x->type()->tag() == y->type()->tag(), "types must match");
1077   pin();
1078 
1079   stringStream strStream;
1080   Compilation::current()->method()->print_name(&strStream);
1081 
1082   stringStream strStream1;
1083   InstructionPrinter ip1(1, &strStream1);
1084   ip1.print_instr(x);
1085 
1086   stringStream strStream2;
1087   InstructionPrinter ip2(1, &strStream2);
1088   ip2.print_instr(y);
1089 
1090   stringStream ss;
1091   ss.print("Assertion %s %s %s in method %s", strStream1.freeze(), ip2.cond_name(cond), strStream2.freeze(), strStream.freeze());
1092 
1093   _message = ss.as_string();
1094 }
1095 #endif
1096 
1097 void RangeCheckPredicate::check_state() {
1098   assert(state()->kind() != ValueStack::EmptyExceptionState && state()->kind() != ValueStack::ExceptionState, "will deopt with empty state");
1099 }
1100 
1101 void ProfileInvoke::state_values_do(ValueVisitor* f) {
1102   if (state() != nullptr) state()->values_do(f);
1103 }
1104