1 /* 2 * Copyright (c) 2017, 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 "gc/shared/gcLocker.inline.hpp" 27 #include "interpreter/interpreter.hpp" 28 #include "logging/log.hpp" 29 #include "memory/metadataFactory.hpp" 30 #include "oops/oop.inline.hpp" 31 #include "oops/fieldStreams.hpp" 32 #include "oops/method.hpp" 33 #include "oops/objArrayKlass.hpp" 34 #include "oops/valueKlass.hpp" 35 #include "oops/valueArrayKlass.hpp" 36 #include "runtime/signature.hpp" 37 #include "utilities/copy.hpp" 38 39 int ValueKlass::first_field_offset() const { 40 #ifdef ASSERT 41 int first_offset = INT_MAX; 42 for (JavaFieldStream fs(this); !fs.done(); fs.next()) { 43 if (fs.offset() < first_offset) first_offset= fs.offset(); 44 } 45 #endif 46 int base_offset = instanceOopDesc::base_offset_in_bytes(); 47 // The first field of value types is aligned on a long boundary 48 base_offset = align_up(base_offset, BytesPerLong); 49 assert(base_offset == first_offset, "inconsistent offsets"); 50 return base_offset; 51 } 52 53 int ValueKlass::raw_value_byte_size() const { 54 assert(!is__Value(), "This is not the value type klass you are looking for"); 55 int heapOopAlignedSize = nonstatic_field_size() << LogBytesPerHeapOop; 56 // If bigger than 64 bits or needs oop alignment, then use jlong aligned 57 // which for values should be jlong aligned, asserts in raw_field_copy otherwise 58 if (heapOopAlignedSize >= longSize || contains_oops()) { 59 return heapOopAlignedSize; 60 } 61 // Small primitives... 62 // If a few small basic type fields, return the actual size, i.e. 63 // 1 byte = 1 64 // 2 byte = 2 65 // 3 byte = 4, because pow2 needed for element stores 66 int first_offset = first_field_offset(); 67 int last_offset = 0; // find the last offset, add basic type size 68 int last_tsz = 0; 69 for (JavaFieldStream fs(this); !fs.done(); fs.next()) { 70 if (fs.offset() > last_offset) { 71 BasicType type = fs.field_descriptor().field_type(); 72 if (is_java_primitive(type)) { 73 last_tsz = type2aelembytes(type); 74 } else if (type == T_VALUETYPE) { 75 // Not just primitives. Layout aligns embedded value, so use jlong aligned it is 76 return heapOopAlignedSize; 77 } else { 78 guarantee(0, "Unknown type %d", type); 79 } 80 assert(last_tsz != 0, "Invariant"); 81 last_offset = fs.offset(); 82 } 83 } 84 // Assumes VT with no fields are meaningless and illegal 85 last_offset += last_tsz; 86 assert(last_offset > first_offset && last_tsz, "Invariant"); 87 return 1 << upper_log2(last_offset - first_offset); 88 } 89 90 instanceOop ValueKlass::allocate_instance(TRAPS) { 91 int size = size_helper(); // Query before forming handle. 92 93 return (instanceOop)CollectedHeap::obj_allocate(this, size, CHECK_NULL); 94 } 95 96 instanceOop ValueKlass::allocate_buffered_or_heap_instance(bool* in_heap, TRAPS) { 97 assert(THREAD->is_Java_thread(), "Only Java threads can call this method"); 98 99 instanceOop value = NULL; 100 if (is_bufferable()) { 101 value = (instanceOop)VTBuffer::allocate_value(this, CHECK_NULL); 102 *in_heap = false; 103 } 104 if (value == NULL) { 105 log_info(valuetypes)("Value buffering failed, allocating in the Java heap"); 106 value = allocate_instance(CHECK_NULL); 107 *in_heap = true; 108 } 109 return value; 110 } 111 112 bool ValueKlass::is_atomic() { 113 return (nonstatic_field_size() * heapOopSize) <= longSize; 114 } 115 116 int ValueKlass::nonstatic_oop_count() { 117 int oops = 0; 118 int map_count = nonstatic_oop_map_count(); 119 OopMapBlock* block = start_of_nonstatic_oop_maps(); 120 OopMapBlock* end = block + map_count; 121 while (block != end) { 122 oops += block->count(); 123 block++; 124 } 125 return oops; 126 } 127 128 // Arrays of... 129 130 bool ValueKlass::flatten_array() { 131 if (!ValueArrayFlatten) { 132 return false; 133 } 134 135 int elem_bytes = raw_value_byte_size(); 136 // Too big 137 if ((ValueArrayElemMaxFlatSize >= 0) && (elem_bytes > ValueArrayElemMaxFlatSize)) { 138 return false; 139 } 140 // Too many embedded oops 141 if ((ValueArrayElemMaxFlatOops >= 0) && (nonstatic_oop_count() > ValueArrayElemMaxFlatOops)) { 142 return false; 143 } 144 145 return true; 146 } 147 148 149 Klass* ValueKlass::array_klass_impl(bool or_null, int n, TRAPS) { 150 if (!flatten_array()) { 151 return InstanceKlass::array_klass_impl(or_null, n, THREAD); 152 } 153 154 // Basically the same as instanceKlass, but using "ValueArrayKlass::allocate_klass" 155 if (array_klasses() == NULL) { 156 if (or_null) return NULL; 157 158 ResourceMark rm; 159 JavaThread *jt = (JavaThread *)THREAD; 160 { 161 // Atomic creation of array_klasses 162 MutexLocker mc(Compile_lock, THREAD); // for vtables 163 MutexLocker ma(MultiArray_lock, THREAD); 164 165 // Check if update has already taken place 166 if (array_klasses() == NULL) { 167 Klass* ak; 168 if (is_atomic() || (!ValueArrayAtomicAccess)) { 169 ak = ValueArrayKlass::allocate_klass(this, CHECK_NULL); 170 } else { 171 ak = ObjArrayKlass::allocate_objArray_klass(class_loader_data(), 1, this, CHECK_NULL); 172 } 173 set_array_klasses(ak); 174 } 175 } 176 } 177 // _this will always be set at this point 178 ArrayKlass* ak = ArrayKlass::cast(array_klasses()); 179 if (or_null) { 180 return ak->array_klass_or_null(n); 181 } 182 return ak->array_klass(n, THREAD); 183 } 184 185 Klass* ValueKlass::array_klass_impl(bool or_null, TRAPS) { 186 return array_klass_impl(or_null, 1, THREAD); 187 } 188 189 void ValueKlass::raw_field_copy(void* src, void* dst, size_t raw_byte_size) { 190 /* 191 * Try not to shear fields even if not an atomic store... 192 * 193 * First 3 cases handle value array store, otherwise works on the same basis 194 * as JVM_Clone, at this size data is aligned. The order of primitive types 195 * is largest to smallest, and it not possible for fields to stradle long 196 * copy boundaries. 197 * 198 * If MT without exclusive access, possible to observe partial value store, 199 * but not partial primitive and reference field values 200 */ 201 switch (raw_byte_size) { 202 case 1: 203 *((jbyte*) dst) = *(jbyte*)src; 204 break; 205 case 2: 206 *((jshort*) dst) = *(jshort*)src; 207 break; 208 case 4: 209 *((jint*) dst) = *(jint*) src; 210 break; 211 default: 212 assert(raw_byte_size % sizeof(jlong) == 0, "Unaligned raw_byte_size"); 213 Copy::conjoint_jlongs_atomic((jlong*)src, (jlong*)dst, raw_byte_size >> LogBytesPerLong); 214 } 215 } 216 217 /* 218 * Store the value of this klass contained with src into dst. 219 * 220 * This operation is appropriate for use from vastore, vaload and putfield (for values) 221 * 222 * GC barriers currently can lock with no safepoint check and allocate c-heap, 223 * so raw point is "safe" for now. 224 * 225 * Going forward, look to use machine generated (stub gen or bc) version for most used klass layouts 226 * 227 */ 228 void ValueKlass::value_store(void* src, void* dst, size_t raw_byte_size, bool dst_heap, bool dst_uninitialized) { 229 if (contains_oops() && dst_heap) { 230 // src/dst aren't oops, need offset to adjust oop map offset 231 const address dst_oop_addr = ((address) dst) - first_field_offset(); 232 233 // Pre-barriers... 234 OopMapBlock* map = start_of_nonstatic_oop_maps(); 235 OopMapBlock* const end = map + nonstatic_oop_map_count(); 236 while (map != end) { 237 // Shame we can't just use the existing oop iterator...src/dst aren't oop 238 address doop_address = dst_oop_addr + map->offset(); 239 if (UseCompressedOops) { 240 oopDesc::bs()->write_ref_array_pre((narrowOop*) doop_address, map->count(), dst_uninitialized); 241 } else { 242 oopDesc::bs()->write_ref_array_pre((oop*) doop_address, map->count(), dst_uninitialized); 243 } 244 map++; 245 } 246 247 raw_field_copy(src, dst, raw_byte_size); 248 249 // Post-barriers... 250 map = start_of_nonstatic_oop_maps(); 251 while (map != end) { 252 address doop_address = dst_oop_addr + map->offset(); 253 oopDesc::bs()->write_ref_array((HeapWord*) doop_address, map->count()); 254 map++; 255 } 256 } else { // Primitive-only case... 257 raw_field_copy(src, dst, raw_byte_size); 258 } 259 } 260 261 oop ValueKlass::box(Handle src, InstanceKlass* target_klass, TRAPS) { 262 assert(src()->klass()->is_value(), "src must be a value type"); 263 assert(!target_klass->is_value(), "target_klass must not be a value type"); 264 265 target_klass->initialize(CHECK_0); 266 instanceOop box = target_klass->allocate_instance(CHECK_0); 267 value_store(data_for_oop(src()), data_for_oop(box), true, false); 268 269 assert(!box->klass()->is_value(), "Sanity check"); 270 return box; 271 } 272 273 oop ValueKlass::unbox(Handle src, InstanceKlass* target_klass, TRAPS) { 274 assert(!src()->klass()->is_value(), "src must not be a value type"); 275 assert(target_klass->is_value(), "target_klass must be a value type"); 276 ValueKlass* vtklass = ValueKlass::cast(target_klass); 277 278 vtklass->initialize(CHECK_0); 279 bool in_heap; 280 instanceOop value = vtklass->allocate_buffered_or_heap_instance(&in_heap, CHECK_0); 281 value_store(data_for_oop(src()), data_for_oop(value), in_heap, false); 282 283 assert(value->klass()->is_value(), "Sanity check"); 284 return value; 285 } 286 287 // Value type arguments are not passed by reference, instead each 288 // field of the value type is passed as an argument. This helper 289 // function collects the fields of the value types (including embedded 290 // value type's fields) in a list. Included with the field's type is 291 // the offset of each field in the value type: i2c and c2i adapters 292 // need that to load or store fields. Finally, the list of fields is 293 // sorted in order of increasing offsets: the adapters and the 294 // compiled code need and agreed upon order of fields. 295 // 296 // The list of basic types that is returned starts with a T_VALUETYPE 297 // and ends with an extra T_VOID. T_VALUETYPE/T_VOID are used as 298 // delimiters. Every entry between the two is a field of the value 299 // type. If there's an embedded value type in the list, it also starts 300 // with a T_VALUETYPE and ends with a T_VOID. This is so we can 301 // generate a unique fingerprint for the method's adapters and we can 302 // generate the list of basic types from the interpreter point of view 303 // (value types passed as reference: iterate on the list until a 304 // T_VALUETYPE, drop everything until and including the closing 305 // T_VOID) or the compiler point of view (each field of the value 306 // types is an argument: drop all T_VALUETYPE/T_VOID from the list). 307 GrowableArray<SigEntry> ValueKlass::collect_fields(int base_off) const { 308 GrowableArray<SigEntry> sig_extended; 309 sig_extended.push(SigEntry(T_VALUETYPE, base_off)); 310 for (JavaFieldStream fs(this); !fs.done(); fs.next()) { 311 if (fs.access_flags().is_static()) continue; 312 fieldDescriptor& fd = fs.field_descriptor(); 313 BasicType bt = fd.field_type(); 314 int offset = base_off + fd.offset() - (base_off > 0 ? first_field_offset() : 0); 315 if (bt == T_VALUETYPE) { 316 if (fd.is_flatten()) { 317 Symbol* signature = fd.signature(); 318 JavaThread* THREAD = JavaThread::current(); 319 oop loader = class_loader(); 320 oop domain = protection_domain(); 321 ResetNoHandleMark rnhm; 322 HandleMark hm; 323 NoSafepointVerifier nsv; 324 Klass* klass = SystemDictionary::resolve_or_null(signature, 325 Handle(THREAD, loader), Handle(THREAD, domain), 326 THREAD); 327 assert(klass != NULL && !HAS_PENDING_EXCEPTION, "lookup shouldn't fail"); 328 const GrowableArray<SigEntry>& embedded = ValueKlass::cast(klass)->collect_fields(offset); 329 sig_extended.appendAll(&embedded); 330 } else { 331 sig_extended.push(SigEntry(T_VALUETYPEPTR, offset)); 332 } 333 } else { 334 sig_extended.push(SigEntry(bt, offset)); 335 if (bt == T_LONG || bt == T_DOUBLE) { 336 sig_extended.push(SigEntry(T_VOID, offset)); 337 } 338 } 339 } 340 int offset = base_off + size_helper()*HeapWordSize - (base_off > 0 ? first_field_offset() : 0); 341 sig_extended.push(SigEntry(T_VOID, offset)); // hack: use T_VOID to mark end of value type fields 342 if (base_off == 0) { 343 sig_extended.sort(SigEntry::compare); 344 } 345 assert(sig_extended.at(0)._bt == T_VALUETYPE && sig_extended.at(sig_extended.length()-1)._bt == T_VOID, "broken structure"); 346 return sig_extended; 347 } 348 349 void ValueKlass::initialize_calling_convention() { 350 // Because the pack and unpack handler addresses need to be loadable from generated code, 351 // they are stored at a fixed offset in the klass metadata. Since value type klasses do 352 // not have a vtable, the vtable offset is used to store these addresses. 353 guarantee(vtable_length() == 0, "vtables are not supported in value klasses"); 354 if (ValueTypeReturnedAsFields || ValueTypePassFieldsAsArgs) { 355 Thread* THREAD = Thread::current(); 356 assert(!HAS_PENDING_EXCEPTION, "should have no exception"); 357 ResourceMark rm; 358 const GrowableArray<SigEntry>& sig_vk = collect_fields(); 359 int nb_fields = SigEntry::count_fields(sig_vk)+1; 360 Array<SigEntry>* extended_sig = MetadataFactory::new_array<SigEntry>(class_loader_data(), sig_vk.length(), CHECK_AND_CLEAR); 361 *((Array<SigEntry>**)adr_extended_sig()) = extended_sig; 362 for (int i = 0; i < sig_vk.length(); i++) { 363 extended_sig->at_put(i, sig_vk.at(i)); 364 } 365 366 if (ValueTypeReturnedAsFields) { 367 BasicType* sig_bt = NEW_RESOURCE_ARRAY(BasicType, nb_fields); 368 sig_bt[0] = T_METADATA; 369 SigEntry::fill_sig_bt(sig_vk, sig_bt+1, nb_fields-1, true); 370 VMRegPair* regs = NEW_RESOURCE_ARRAY(VMRegPair, nb_fields); 371 int total = SharedRuntime::java_return_convention(sig_bt, regs, nb_fields); 372 373 if (total > 0) { 374 Array<VMRegPair>* return_regs = MetadataFactory::new_array<VMRegPair>(class_loader_data(), nb_fields, CHECK_AND_CLEAR); 375 *((Array<VMRegPair>**)adr_return_regs()) = return_regs; 376 for (int i = 0; i < nb_fields; i++) { 377 return_regs->at_put(i, regs[i]); 378 } 379 380 BufferedValueTypeBlob* buffered_blob = SharedRuntime::generate_buffered_value_type_adapter(this); 381 *((address*)adr_pack_handler()) = buffered_blob->pack_fields(); 382 *((address*)adr_unpack_handler()) = buffered_blob->unpack_fields(); 383 assert(CodeCache::find_blob(pack_handler()) == buffered_blob, "lost track of blob"); 384 } 385 } 386 } 387 } 388 389 void ValueKlass::deallocate_contents(ClassLoaderData* loader_data) { 390 if (extended_sig() != NULL) { 391 MetadataFactory::free_array<SigEntry>(loader_data, extended_sig()); 392 } 393 if (return_regs() != NULL) { 394 MetadataFactory::free_array<VMRegPair>(loader_data, return_regs()); 395 } 396 cleanup_blobs(); 397 InstanceKlass::deallocate_contents(loader_data); 398 } 399 400 void ValueKlass::cleanup(ValueKlass* ik) { 401 ik->cleanup_blobs(); 402 } 403 404 void ValueKlass::cleanup_blobs() { 405 if (pack_handler() != NULL) { 406 CodeBlob* buffered_blob = CodeCache::find_blob(pack_handler()); 407 assert(buffered_blob->is_buffered_value_type_blob(), "bad blob type"); 408 BufferBlob::free((BufferBlob*)buffered_blob); 409 *((address*)adr_pack_handler()) = NULL; 410 *((address*)adr_unpack_handler()) = NULL; 411 } 412 } 413 414 // Can this value type be returned as multiple values? 415 bool ValueKlass::can_be_returned_as_fields() const { 416 return !is__Value() && (return_regs() != NULL); 417 } 418 419 // Create handles for all oop fields returned in registers that are going to be live across a safepoint 420 void ValueKlass::save_oop_fields(const RegisterMap& reg_map, GrowableArray<Handle>& handles) const { 421 Thread* thread = Thread::current(); 422 const Array<SigEntry>* sig_vk = extended_sig(); 423 const Array<VMRegPair>* regs = return_regs(); 424 int j = 1; 425 426 for (int i = 0; i < sig_vk->length(); i++) { 427 BasicType bt = sig_vk->at(i)._bt; 428 if (bt == T_OBJECT || bt == T_VALUETYPEPTR || bt == T_ARRAY) { 429 int off = sig_vk->at(i)._offset; 430 VMRegPair pair = regs->at(j); 431 address loc = reg_map.location(pair.first()); 432 oop v = *(oop*)loc; 433 assert(v == NULL || oopDesc::is_oop(v), "not an oop?"); 434 assert(Universe::heap()->is_in_or_null(v), "must be heap pointer"); 435 handles.push(Handle(thread, v)); 436 } 437 if (bt == T_VALUETYPE) { 438 continue; 439 } 440 if (bt == T_VOID && 441 sig_vk->at(i-1)._bt != T_LONG && 442 sig_vk->at(i-1)._bt != T_DOUBLE) { 443 continue; 444 } 445 j++; 446 } 447 assert(j == regs->length(), "missed a field?"); 448 } 449 450 // Update oop fields in registers from handles after a safepoint 451 void ValueKlass::restore_oop_results(RegisterMap& reg_map, GrowableArray<Handle>& handles) const { 452 assert(ValueTypeReturnedAsFields, "inconsistent"); 453 const Array<SigEntry>* sig_vk = extended_sig(); 454 const Array<VMRegPair>* regs = return_regs(); 455 assert(regs != NULL, "inconsistent"); 456 457 int j = 1; 458 for (int i = 0, k = 0; i < sig_vk->length(); i++) { 459 BasicType bt = sig_vk->at(i)._bt; 460 if (bt == T_OBJECT || bt == T_ARRAY) { 461 int off = sig_vk->at(i)._offset; 462 VMRegPair pair = regs->at(j); 463 address loc = reg_map.location(pair.first()); 464 *(oop*)loc = handles.at(k++)(); 465 } 466 if (bt == T_VALUETYPE) { 467 continue; 468 } 469 if (bt == T_VOID && 470 sig_vk->at(i-1)._bt != T_LONG && 471 sig_vk->at(i-1)._bt != T_DOUBLE) { 472 continue; 473 } 474 j++; 475 } 476 assert(j == regs->length(), "missed a field?"); 477 } 478 479 // Fields are in registers. Create an instance of the value type and 480 // initialize it with the values of the fields. 481 oop ValueKlass::realloc_result(const RegisterMap& reg_map, const GrowableArray<Handle>& handles, bool buffered, TRAPS) { 482 bool ignored = false; 483 oop new_vt = NULL; 484 if (buffered) { 485 new_vt = allocate_buffered_or_heap_instance(&ignored, CHECK_NULL); 486 } else { 487 new_vt = allocate_instance(CHECK_NULL); 488 } 489 490 const Array<SigEntry>* sig_vk = extended_sig(); 491 const Array<VMRegPair>* regs = return_regs(); 492 493 int j = 1; 494 int k = 0; 495 for (int i = 0; i < sig_vk->length(); i++) { 496 BasicType bt = sig_vk->at(i)._bt; 497 if (bt == T_VALUETYPE) { 498 continue; 499 } 500 if (bt == T_VOID) { 501 if (sig_vk->at(i-1)._bt == T_LONG || 502 sig_vk->at(i-1)._bt == T_DOUBLE) { 503 j++; 504 } 505 continue; 506 } 507 int off = sig_vk->at(i)._offset; 508 VMRegPair pair = regs->at(j); 509 address loc = reg_map.location(pair.first()); 510 switch(bt) { 511 case T_BOOLEAN: { 512 jboolean v = *(intptr_t*)loc; 513 *(jboolean*)((address)new_vt + off) = v; 514 break; 515 } 516 case T_CHAR: { 517 jchar v = *(intptr_t*)loc; 518 *(jchar*)((address)new_vt + off) = v; 519 break; 520 } 521 case T_BYTE: { 522 jbyte v = *(intptr_t*)loc; 523 *(jbyte*)((address)new_vt + off) = v; 524 break; 525 } 526 case T_SHORT: { 527 jshort v = *(intptr_t*)loc; 528 *(jshort*)((address)new_vt + off) = v; 529 break; 530 } 531 case T_INT: { 532 jint v = *(intptr_t*)loc; 533 *(jint*)((address)new_vt + off) = v; 534 break; 535 } 536 case T_LONG: { 537 #ifdef _LP64 538 jlong v = *(intptr_t*)loc; 539 *(jlong*)((address)new_vt + off) = v; 540 #else 541 Unimplemented(); 542 #endif 543 break; 544 } 545 case T_OBJECT: 546 case T_VALUETYPEPTR: 547 case T_ARRAY: { 548 Handle handle = handles.at(k++); 549 oop v = handle(); 550 if (!UseCompressedOops) { 551 oop* p = (oop*)((address)new_vt + off); 552 oopDesc::store_heap_oop(p, v); 553 } else { 554 narrowOop* p = (narrowOop*)((address)new_vt + off); 555 oopDesc::encode_store_heap_oop(p, v); 556 } 557 break; 558 } 559 case T_FLOAT: { 560 jfloat v = *(jfloat*)loc; 561 *(jfloat*)((address)new_vt + off) = v; 562 break; 563 } 564 case T_DOUBLE: { 565 jdouble v = *(jdouble*)loc; 566 *(jdouble*)((address)new_vt + off) = v; 567 break; 568 } 569 default: 570 ShouldNotReachHere(); 571 } 572 *(intptr_t*)loc = 0xDEAD; 573 j++; 574 } 575 assert(j == regs->length(), "missed a field?"); 576 assert(k == handles.length(), "missed an oop?"); 577 return new_vt; 578 } 579 580 // Check the return register for a ValueKlass oop 581 ValueKlass* ValueKlass::returned_value_klass(const RegisterMap& map) { 582 BasicType bt = T_METADATA; 583 VMRegPair pair; 584 int nb = SharedRuntime::java_return_convention(&bt, &pair, 1); 585 assert(nb == 1, "broken"); 586 587 address loc = map.location(pair.first()); 588 intptr_t ptr = *(intptr_t*)loc; 589 if (is_set_nth_bit(ptr, 0)) { 590 // Oop is tagged, must be a ValueKlass oop 591 clear_nth_bit(ptr, 0); 592 assert(Metaspace::contains((void*)ptr), "should be klass"); 593 ValueKlass* vk = (ValueKlass*)ptr; 594 assert(vk->can_be_returned_as_fields(), "must be able to return as fields"); 595 return vk; 596 } 597 #ifdef ASSERT 598 // Oop is not tagged, must be a valid oop 599 if (VerifyOops) { 600 oop((HeapWord*)ptr)->verify(); 601 } 602 #endif 603 return NULL; 604 }