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 }