1 /*
   2  * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "compiler/compileLog.hpp"
  27 #include "interpreter/linkResolver.hpp"
  28 #include "memory/universe.inline.hpp"
  29 #include "oops/objArrayKlass.hpp"
  30 #include "opto/addnode.hpp"
  31 #include "opto/castnode.hpp"
  32 #include "opto/memnode.hpp"
  33 #include "opto/parse.hpp"
  34 #include "opto/rootnode.hpp"
  35 #include "opto/runtime.hpp"
  36 #include "opto/subnode.hpp"
  37 #include "opto/valuetypenode.hpp"
  38 #include "runtime/deoptimization.hpp"
  39 #include "runtime/handles.inline.hpp"
  40 
  41 //=============================================================================
  42 // Helper methods for _get* and _put* bytecodes
  43 //=============================================================================
  44 bool Parse::static_field_ok_in_clinit(ciField *field, ciMethod *method) {
  45   // Could be the field_holder's <clinit> method, or <clinit> for a subklass.
  46   // Better to check now than to Deoptimize as soon as we execute
  47   assert( field->is_static(), "Only check if field is static");
  48   // is_being_initialized() is too generous.  It allows access to statics
  49   // by threads that are not running the <clinit> before the <clinit> finishes.
  50   // return field->holder()->is_being_initialized();
  51 
  52   // The following restriction is correct but conservative.
  53   // It is also desirable to allow compilation of methods called from <clinit>
  54   // but this generated code will need to be made safe for execution by
  55   // other threads, or the transition from interpreted to compiled code would
  56   // need to be guarded.
  57   ciInstanceKlass *field_holder = field->holder();
  58 
  59   bool access_OK = false;
  60   if (method->holder()->is_subclass_of(field_holder)) {
  61     if (method->is_static()) {
  62       if (method->name() == ciSymbol::class_initializer_name()) {
  63         // OK to access static fields inside initializer
  64         access_OK = true;
  65       }
  66     } else {
  67       if (method->name() == ciSymbol::object_initializer_name()) {
  68         // It's also OK to access static fields inside a constructor,
  69         // because any thread calling the constructor must first have
  70         // synchronized on the class by executing a '_new' bytecode.
  71         access_OK = true;
  72       }
  73     }
  74   }
  75 
  76   return access_OK;
  77 
  78 }
  79 
  80 
  81 void Parse::do_field_access(bool is_get, bool is_field) {
  82   bool will_link;
  83   ciField* field = iter().get_field(will_link);
  84   assert(will_link, "getfield: typeflow responsibility");
  85 
  86   ciInstanceKlass* field_holder = field->holder();
  87 
  88   if (is_field == field->is_static()) {
  89     // Interpreter will throw java_lang_IncompatibleClassChangeError
  90     // Check this before allowing <clinit> methods to access static fields
  91     uncommon_trap(Deoptimization::Reason_unhandled,
  92                   Deoptimization::Action_none);
  93     return;
  94   }
  95 
  96   if (!is_field && !field_holder->is_initialized()) {
  97     if (!static_field_ok_in_clinit(field, method())) {
  98       uncommon_trap(Deoptimization::Reason_uninitialized,
  99                     Deoptimization::Action_reinterpret,
 100                     NULL, "!static_field_ok_in_clinit");
 101       return;
 102     }
 103   }
 104 
 105   // Deoptimize on putfield writes to call site target field.
 106   if (!is_get && field->is_call_site_target()) {
 107     uncommon_trap(Deoptimization::Reason_unhandled,
 108                   Deoptimization::Action_reinterpret,
 109                   NULL, "put to call site target field");
 110     return;
 111   }
 112 
 113   assert(field->will_link(method()->holder(), bc()), "getfield: typeflow responsibility");
 114 
 115   // Note:  We do not check for an unloaded field type here any more.
 116 
 117   // Generate code for the object pointer.
 118   Node* obj;
 119   if (is_field) {
 120     int obj_depth = is_get ? 0 : field->type()->size();
 121     obj = null_check(peek(obj_depth));
 122     // Compile-time detect of null-exception?
 123     if (stopped())  return;
 124 
 125 #ifdef ASSERT
 126     const TypeInstPtr *tjp = TypeInstPtr::make(TypePtr::NotNull, iter().get_declared_field_holder());
 127     assert(_gvn.type(obj)->higher_equal(tjp), "cast_up is no longer needed");
 128 #endif
 129 
 130     if (is_get) {
 131       (void) pop();  // pop receiver before getting
 132       do_get_xxx(obj, field, is_field);
 133     } else {
 134       do_put_xxx(obj, field, is_field);
 135       (void) pop();  // pop receiver after putting
 136     }
 137   } else {
 138     const TypeInstPtr* tip = TypeInstPtr::make(field_holder->java_mirror());
 139     obj = _gvn.makecon(tip);
 140     if (is_get) {
 141       do_get_xxx(obj, field, is_field);
 142     } else {
 143       do_put_xxx(obj, field, is_field);
 144     }
 145   }
 146 }
 147 
 148 void Parse::do_vgetfield() {
 149   // fixme null/top check?
 150   bool will_link;
 151   ciField* field = iter().get_field(will_link);
 152   BasicType bt = field->layout_type();
 153   ValueTypeNode* vt = pop()->as_ValueType();
 154   Node* value = vt->field_value_by_offset(field->offset());
 155   push_node(bt, value);
 156 }
 157 
 158 void Parse::do_get_xxx(Node* obj, ciField* field, bool is_field) {
 159   BasicType bt = field->layout_type();
 160   // Does this field have a constant value?  If so, just push the value.
 161   if (field->is_constant()) {
 162     // final or stable field
 163     const Type* con_type = Type::make_constant(field, obj);
 164     if (con_type != NULL) {
 165       Node* con = makecon(con_type);
 166       if (bt == T_VALUETYPE) {
 167         // Load value type from constant oop
 168         con = ValueTypeNode::make(gvn(), map()->memory(), con);
 169       }
 170       push_node(con_type->basic_type(), con);
 171       return;
 172     }
 173   }
 174 
 175   ciType* field_klass = field->type();
 176   bool is_vol = field->is_volatile();
 177 
 178   // Compute address and memory type.
 179   int offset = field->offset_in_bytes();
 180   const TypePtr* adr_type = C->alias_type(field)->adr_type();
 181   Node *adr = basic_plus_adr(obj, obj, offset);
 182 
 183   // Build the resultant type of the load
 184   const Type *type;
 185 
 186   bool must_assert_null = false;
 187 
 188   if (bt == T_OBJECT || bt == T_VALUETYPE) {
 189     if (!field->type()->is_loaded()) {
 190       type = TypeInstPtr::BOTTOM;
 191       must_assert_null = true;
 192     } else if (field->is_constant() && field->is_static()) {
 193       // This can happen if the constant oop is non-perm.
 194       ciObject* con = field->constant_value().as_object();
 195       // Do not "join" in the previous type; it doesn't add value,
 196       // and may yield a vacuous result if the field is of interface type.
 197       type = TypeOopPtr::make_from_constant(con)->isa_oopptr();
 198       assert(type != NULL, "field singleton type must be consistent");
 199     } else {
 200       type = TypeOopPtr::make_from_klass(field_klass->as_klass());
 201     }
 202   } else {
 203     type = Type::get_const_basic_type(bt);
 204   }
 205   if (support_IRIW_for_not_multiple_copy_atomic_cpu && field->is_volatile()) {
 206     insert_mem_bar(Op_MemBarVolatile);   // StoreLoad barrier
 207   }
 208 
 209   // Build the load.
 210   //
 211   MemNode::MemOrd mo = is_vol ? MemNode::acquire : MemNode::unordered;
 212   bool needs_atomic_access = is_vol || AlwaysAtomicAccesses;
 213   Node* ld = NULL;
 214    if (bt == T_VALUETYPE && !field->is_static()) {
 215     // Load flattened value type from non-static field
 216     ld = ValueTypeNode::make(_gvn, field_klass->as_value_klass(), map()->memory(), field->holder(), obj, offset);
 217   } else {
 218     ld = make_load(NULL, adr, type, bt, adr_type, mo, LoadNode::DependsOnlyOnTest, needs_atomic_access);
 219   }
 220 
 221   // Adjust Java stack
 222   if (type2size[bt] == 1)
 223     push(ld);
 224   else
 225     push_pair(ld);
 226 
 227   if (must_assert_null) {
 228     // Do not take a trap here.  It's possible that the program
 229     // will never load the field's class, and will happily see
 230     // null values in this field forever.  Don't stumble into a
 231     // trap for such a program, or we might get a long series
 232     // of useless recompilations.  (Or, we might load a class
 233     // which should not be loaded.)  If we ever see a non-null
 234     // value, we will then trap and recompile.  (The trap will
 235     // not need to mention the class index, since the class will
 236     // already have been loaded if we ever see a non-null value.)
 237     // uncommon_trap(iter().get_field_signature_index());
 238     if (PrintOpto && (Verbose || WizardMode)) {
 239       method()->print_name(); tty->print_cr(" asserting nullness of field at bci: %d", bci());
 240     }
 241     if (C->log() != NULL) {
 242       C->log()->elem("assert_null reason='field' klass='%d'",
 243                      C->log()->identify(field->type()));
 244     }
 245     // If there is going to be a trap, put it at the next bytecode:
 246     set_bci(iter().next_bci());
 247     null_assert(peek());
 248     set_bci(iter().cur_bci()); // put it back
 249   }
 250 
 251   // If reference is volatile, prevent following memory ops from
 252   // floating up past the volatile read.  Also prevents commoning
 253   // another volatile read.
 254   if (field->is_volatile()) {
 255     // Memory barrier includes bogus read of value to force load BEFORE membar
 256     insert_mem_bar(Op_MemBarAcquire, ld);
 257   }
 258 }
 259 
 260 void Parse::do_put_xxx(Node* obj, ciField* field, bool is_field) {
 261   bool is_vol = field->is_volatile();
 262   // If reference is volatile, prevent following memory ops from
 263   // floating down past the volatile write.  Also prevents commoning
 264   // another volatile read.
 265   if (is_vol)  insert_mem_bar(Op_MemBarRelease);
 266 
 267   // Compute address and memory type.
 268   int offset = field->offset_in_bytes();
 269   const TypePtr* adr_type = C->alias_type(field)->adr_type();
 270   Node* adr = basic_plus_adr(obj, obj, offset);
 271   BasicType bt = field->layout_type();
 272   // Value to be stored
 273   Node* val = type2size[bt] == 1 ? pop() : pop_pair();
 274   // Round doubles before storing
 275   if (bt == T_DOUBLE)  val = dstore_rounding(val);
 276 
 277   // Conservatively release stores of object references.
 278   const MemNode::MemOrd mo =
 279     is_vol ?
 280     // Volatile fields need releasing stores.
 281     MemNode::release :
 282     // Non-volatile fields also need releasing stores if they hold an
 283     // object reference, because the object reference might point to
 284     // a freshly created object.
 285     StoreNode::release_if_reference(bt);
 286 
 287   // Store the value.
 288   if (bt == T_OBJECT || bt == T_VALUETYPE) {
 289     const TypeOopPtr* field_type;
 290     if (!field->type()->is_loaded()) {
 291       field_type = TypeInstPtr::BOTTOM;
 292     } else {
 293       field_type = TypeOopPtr::make_from_klass(field->type()->as_klass());
 294     }
 295     if (bt == T_VALUETYPE && !field->is_static()) {
 296       // Store flattened value type to non-static field
 297       val->as_ValueType()->store_to_field(this, field->holder(), obj, offset);
 298     } else {
 299       store_oop_to_object(control(), obj, adr, adr_type, val, field_type, bt, mo);
 300     }
 301   } else {
 302     bool needs_atomic_access = is_vol || AlwaysAtomicAccesses;
 303     store_to_memory(control(), adr, val, bt, adr_type, mo, needs_atomic_access);
 304   }
 305 
 306   // If reference is volatile, prevent following volatiles ops from
 307   // floating up before the volatile write.
 308   if (is_vol) {
 309     // If not multiple copy atomic, we do the MemBarVolatile before the load.
 310     if (!support_IRIW_for_not_multiple_copy_atomic_cpu) {
 311       insert_mem_bar(Op_MemBarVolatile); // Use fat membar
 312     }
 313     // Remember we wrote a volatile field.
 314     // For not multiple copy atomic cpu (ppc64) a barrier should be issued
 315     // in constructors which have such stores. See do_exits() in parse1.cpp.
 316     if (is_field) {
 317       set_wrote_volatile(true);
 318     }
 319   }
 320 
 321   if (is_field) {
 322     set_wrote_fields(true);
 323   }
 324 
 325   // If the field is final, the rules of Java say we are in <init> or <clinit>.
 326   // Note the presence of writes to final non-static fields, so that we
 327   // can insert a memory barrier later on to keep the writes from floating
 328   // out of the constructor.
 329   // Any method can write a @Stable field; insert memory barriers after those also.
 330   if (is_field && (field->is_final() || field->is_stable())) {
 331     if (field->is_final()) {
 332         set_wrote_final(true);
 333     }
 334     if (field->is_stable()) {
 335         set_wrote_stable(true);
 336     }
 337 
 338     // Preserve allocation ptr to create precedent edge to it in membar
 339     // generated on exit from constructor.
 340     // Can't bind stable with its allocation, only record allocation for final field.
 341     if (field->is_final() && AllocateNode::Ideal_allocation(obj, &_gvn) != NULL) {
 342       set_alloc_with_final(obj);
 343     }
 344   }
 345 }
 346 
 347 //=============================================================================
 348 void Parse::do_anewarray() {
 349   bool will_link;
 350   ciKlass* klass = iter().get_klass(will_link);
 351 
 352   // Uncommon Trap when class that array contains is not loaded
 353   // we need the loaded class for the rest of graph; do not
 354   // initialize the container class (see Java spec)!!!
 355   assert(will_link, "anewarray: typeflow responsibility");
 356 
 357   ciObjArrayKlass* array_klass = ciObjArrayKlass::make(klass);
 358   // Check that array_klass object is loaded
 359   if (!array_klass->is_loaded()) {
 360     // Generate uncommon_trap for unloaded array_class
 361     uncommon_trap(Deoptimization::Reason_unloaded,
 362                   Deoptimization::Action_reinterpret,
 363                   array_klass);
 364     return;
 365   }
 366 
 367   kill_dead_locals();
 368 
 369   const TypeKlassPtr* array_klass_type = TypeKlassPtr::make(array_klass);
 370   Node* count_val = pop();
 371   Node* obj = new_array(makecon(array_klass_type), count_val, 1);
 372   push(obj);
 373 }
 374 
 375 
 376 void Parse::do_newarray(BasicType elem_type) {
 377   kill_dead_locals();
 378 
 379   Node*   count_val = pop();
 380   const TypeKlassPtr* array_klass = TypeKlassPtr::make(ciTypeArrayKlass::make(elem_type));
 381   Node*   obj = new_array(makecon(array_klass), count_val, 1);
 382   // Push resultant oop onto stack
 383   push(obj);
 384 }
 385 
 386 // Expand simple expressions like new int[3][5] and new Object[2][nonConLen].
 387 // Also handle the degenerate 1-dimensional case of anewarray.
 388 Node* Parse::expand_multianewarray(ciArrayKlass* array_klass, Node* *lengths, int ndimensions, int nargs) {
 389   Node* length = lengths[0];
 390   assert(length != NULL, "");
 391   Node* array = new_array(makecon(TypeKlassPtr::make(array_klass)), length, nargs);
 392   if (ndimensions > 1) {
 393     jint length_con = find_int_con(length, -1);
 394     guarantee(length_con >= 0, "non-constant multianewarray");
 395     ciArrayKlass* array_klass_1 = array_klass->as_obj_array_klass()->element_klass()->as_array_klass();
 396     const TypePtr* adr_type = TypeAryPtr::OOPS;
 397     const TypeOopPtr*    elemtype = _gvn.type(array)->is_aryptr()->elem()->make_oopptr();
 398     const intptr_t header   = arrayOopDesc::base_offset_in_bytes(T_OBJECT);
 399     for (jint i = 0; i < length_con; i++) {
 400       Node*    elem   = expand_multianewarray(array_klass_1, &lengths[1], ndimensions-1, nargs);
 401       intptr_t offset = header + ((intptr_t)i << LogBytesPerHeapOop);
 402       Node*    eaddr  = basic_plus_adr(array, offset);
 403       store_oop_to_array(control(), array, eaddr, adr_type, elem, elemtype, T_OBJECT, MemNode::unordered);
 404     }
 405   }
 406   return array;
 407 }
 408 
 409 void Parse::do_multianewarray() {
 410   int ndimensions = iter().get_dimensions();
 411 
 412   // the m-dimensional array
 413   bool will_link;
 414   ciArrayKlass* array_klass = iter().get_klass(will_link)->as_array_klass();
 415   assert(will_link, "multianewarray: typeflow responsibility");
 416 
 417   // Note:  Array classes are always initialized; no is_initialized check.
 418 
 419   kill_dead_locals();
 420 
 421   // get the lengths from the stack (first dimension is on top)
 422   Node** length = NEW_RESOURCE_ARRAY(Node*, ndimensions + 1);
 423   length[ndimensions] = NULL;  // terminating null for make_runtime_call
 424   int j;
 425   for (j = ndimensions-1; j >= 0 ; j--) length[j] = pop();
 426 
 427   // The original expression was of this form: new T[length0][length1]...
 428   // It is often the case that the lengths are small (except the last).
 429   // If that happens, use the fast 1-d creator a constant number of times.
 430   const jint expand_limit = MIN2((jint)MultiArrayExpandLimit, 100);
 431   jint expand_count = 1;        // count of allocations in the expansion
 432   jint expand_fanout = 1;       // running total fanout
 433   for (j = 0; j < ndimensions-1; j++) {
 434     jint dim_con = find_int_con(length[j], -1);
 435     expand_fanout *= dim_con;
 436     expand_count  += expand_fanout; // count the level-J sub-arrays
 437     if (dim_con <= 0
 438         || dim_con > expand_limit
 439         || expand_count > expand_limit) {
 440       expand_count = 0;
 441       break;
 442     }
 443   }
 444 
 445   // Can use multianewarray instead of [a]newarray if only one dimension,
 446   // or if all non-final dimensions are small constants.
 447   if (ndimensions == 1 || (1 <= expand_count && expand_count <= expand_limit)) {
 448     Node* obj = NULL;
 449     // Set the original stack and the reexecute bit for the interpreter
 450     // to reexecute the multianewarray bytecode if deoptimization happens.
 451     // Do it unconditionally even for one dimension multianewarray.
 452     // Note: the reexecute bit will be set in GraphKit::add_safepoint_edges()
 453     // when AllocateArray node for newarray is created.
 454     { PreserveReexecuteState preexecs(this);
 455       inc_sp(ndimensions);
 456       // Pass 0 as nargs since uncommon trap code does not need to restore stack.
 457       obj = expand_multianewarray(array_klass, &length[0], ndimensions, 0);
 458     } //original reexecute and sp are set back here
 459     push(obj);
 460     return;
 461   }
 462 
 463   address fun = NULL;
 464   switch (ndimensions) {
 465   case 1: ShouldNotReachHere(); break;
 466   case 2: fun = OptoRuntime::multianewarray2_Java(); break;
 467   case 3: fun = OptoRuntime::multianewarray3_Java(); break;
 468   case 4: fun = OptoRuntime::multianewarray4_Java(); break;
 469   case 5: fun = OptoRuntime::multianewarray5_Java(); break;
 470   };
 471   Node* c = NULL;
 472 
 473   if (fun != NULL) {
 474     c = make_runtime_call(RC_NO_LEAF | RC_NO_IO,
 475                           OptoRuntime::multianewarray_Type(ndimensions),
 476                           fun, NULL, TypeRawPtr::BOTTOM,
 477                           makecon(TypeKlassPtr::make(array_klass)),
 478                           length[0], length[1], length[2],
 479                           (ndimensions > 2) ? length[3] : NULL,
 480                           (ndimensions > 3) ? length[4] : NULL);
 481   } else {
 482     // Create a java array for dimension sizes
 483     Node* dims = NULL;
 484     { PreserveReexecuteState preexecs(this);
 485       inc_sp(ndimensions);
 486       Node* dims_array_klass = makecon(TypeKlassPtr::make(ciArrayKlass::make(ciType::make(T_INT))));
 487       dims = new_array(dims_array_klass, intcon(ndimensions), 0);
 488 
 489       // Fill-in it with values
 490       for (j = 0; j < ndimensions; j++) {
 491         Node *dims_elem = array_element_address(dims, intcon(j), T_INT);
 492         store_to_memory(control(), dims_elem, length[j], T_INT, TypeAryPtr::INTS, MemNode::unordered);
 493       }
 494     }
 495 
 496     c = make_runtime_call(RC_NO_LEAF | RC_NO_IO,
 497                           OptoRuntime::multianewarrayN_Type(),
 498                           OptoRuntime::multianewarrayN_Java(), NULL, TypeRawPtr::BOTTOM,
 499                           makecon(TypeKlassPtr::make(array_klass)),
 500                           dims);
 501   }
 502   make_slow_call_ex(c, env()->Throwable_klass(), false);
 503 
 504   Node* res = _gvn.transform(new ProjNode(c, TypeFunc::Parms));
 505 
 506   const Type* type = TypeOopPtr::make_from_klass_raw(array_klass);
 507 
 508   // Improve the type:  We know it's not null, exact, and of a given length.
 509   type = type->is_ptr()->cast_to_ptr_type(TypePtr::NotNull);
 510   type = type->is_aryptr()->cast_to_exactness(true);
 511 
 512   const TypeInt* ltype = _gvn.find_int_type(length[0]);
 513   if (ltype != NULL)
 514     type = type->is_aryptr()->cast_to_size(ltype);
 515 
 516     // We cannot sharpen the nested sub-arrays, since the top level is mutable.
 517 
 518   Node* cast = _gvn.transform( new CheckCastPPNode(control(), res, type) );
 519   push(cast);
 520 
 521   // Possible improvements:
 522   // - Make a fast path for small multi-arrays.  (W/ implicit init. loops.)
 523   // - Issue CastII against length[*] values, to TypeInt::POS.
 524 }
 525 
 526 void Parse::do_vbox() {
 527   // Obtain a value type from the top of the stack
 528   ValueTypeNode* vt = pop()->as_ValueType();
 529 
 530   // Obtain types
 531   bool will_link;
 532   ciValueKlass* dvt_klass = gvn().type(vt)->is_valuetype()->value_klass();
 533   ciInstanceKlass* vcc_klass = iter().get_klass(will_link)->as_instance_klass();
 534   guarantee(will_link, "value-capable class must be loaded");
 535 
 536   kill_dead_locals();
 537 
 538   // TODO: Generate all (or some) of the following checks
 539   // (1) if target is not an value-capable instance, throw ClassCastException
 540   // (2) if source is not a value type instance, throw ClassCastException
 541   // (3) if target type is not a value type derived from source
 542 
 543   // create new object
 544   Node* kls = makecon(TypeKlassPtr::make(vcc_klass));
 545   Node* obj = new_instance(kls);
 546 
 547   // Store all field values to the newly created object.
 548   // The code below relies on the assumption that the VCC has the
 549   // same memory layout as the derived value type.
 550   // TODO: Once the layout of the two is not the same, update code below.
 551   vt->store_values(this, vcc_klass, obj);
 552 
 553   // Push the new object onto the stack
 554   push(obj);
 555 }
 556 
 557 void Parse::do_vunbox() {
 558   // Obtain object from the top of the stack
 559   Node* obj = pop();
 560 
 561   // Obtain types
 562   bool will_link;
 563   ciInstanceKlass* vcc_klass = gvn().type(obj)->is_oopptr()->klass()->as_instance_klass();
 564   ciValueKlass* dvt_klass = iter().get_klass(will_link)->as_value_klass();
 565   guarantee(will_link, "derived value type must be loaded");
 566 
 567   // TOOD: Generate all the checks. Similar to vbox
 568 
 569   // Create a value type node with the corresponding type
 570   Node* vt = ValueTypeNode::make(gvn(), dvt_klass, map()->memory(), vcc_klass,  obj, dvt_klass->first_field_offset());
 571 
 572   // Push the value type onto the stack
 573   push(vt);
 574 }