1 /*
2 * Copyright (c) 2017, 2026, 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 "classfile/moduleEntry.hpp"
26 #include "classfile/packageEntry.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "classfile/vmSymbols.hpp"
30 #include "gc/shared/collectedHeap.inline.hpp"
31 #include "memory/iterator.inline.hpp"
32 #include "memory/metadataFactory.hpp"
33 #include "memory/metaspaceClosure.hpp"
34 #include "memory/oopFactory.hpp"
35 #include "memory/resourceArea.hpp"
36 #include "memory/universe.hpp"
37 #include "oops/access.hpp"
38 #include "oops/arrayKlass.inline.hpp"
39 #include "oops/arrayOop.hpp"
40 #include "oops/flatArrayKlass.hpp"
41 #include "oops/flatArrayOop.hpp"
42 #include "oops/flatArrayOop.inline.hpp"
43 #include "oops/inlineKlass.hpp"
44 #include "oops/instanceKlass.hpp"
45 #include "oops/klass.inline.hpp"
46 #include "oops/layoutKind.hpp"
47 #include "oops/objArrayKlass.hpp"
48 #include "oops/objArrayOop.inline.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "oops/oopCast.inline.hpp"
51 #include "oops/valuePayload.inline.hpp"
52 #include "oops/verifyOopClosure.hpp"
53 #include "runtime/arguments.hpp"
54 #include "runtime/handles.inline.hpp"
55 #include "runtime/mutexLocker.hpp"
56 #include "utilities/copy.hpp"
57 #include "utilities/macros.hpp"
58
59 // Allocation...
60
61 FlatArrayKlass::FlatArrayKlass(Klass* element_klass, Symbol* name, ArrayProperties props, LayoutKind lk)
62 : ObjArrayKlass(1, element_klass, name, Kind, props),
63 _layout_kind(lk) {
64 assert(element_klass->is_inline_klass(), "Expected Inline");
65 assert(lk != LayoutKind::NULLABLE_NON_ATOMIC_FLAT, "Layout not supported by arrays yet (needs frozen arrays)");
66 assert(LayoutKindHelper::is_flat(lk), "Must be a flat layout");
67
68 assert(_class_loader_data == element_klass->class_loader_data(), "Sanity check");
69
70 set_layout_helper(array_layout_helper(InlineKlass::cast(element_klass), lk));
71 assert(is_array_klass(), "sanity");
72 assert(is_flatArray_klass(), "sanity");
73
74 #ifdef ASSERT
75 assert(layout_helper_is_array(layout_helper()), "Must be");
76 assert(layout_helper_is_flatArray(layout_helper()), "Must be");
77 assert(layout_helper_element_type(layout_helper()) == T_FLAT_ELEMENT, "Must be");
78 assert(prototype_header().is_flat_array(), "Must be");
79 switch(lk) {
80 case LayoutKind::NULL_FREE_NON_ATOMIC_FLAT:
81 case LayoutKind::NULL_FREE_ATOMIC_FLAT:
82 assert(layout_helper_is_null_free(layout_helper()), "Must be");
83 assert(prototype_header().is_null_free_array(), "Must be");
84 break;
85 case LayoutKind::NULLABLE_ATOMIC_FLAT:
86 assert(!layout_helper_is_null_free(layout_helper()), "Must be");
87 assert(!prototype_header().is_null_free_array(), "Must be");
88 break;
89 case LayoutKind::NULLABLE_NON_ATOMIC_FLAT:
90 ShouldNotReachHere();
91 default:
92 ShouldNotReachHere();
93 break;
94 }
95 #endif // ASSERT
96
97 if (PrintFlatArrayLayout) {
98 print();
99 }
100 }
101
102 FlatArrayKlass* FlatArrayKlass::allocate_klass(Klass* eklass, ArrayProperties props, LayoutKind lk, TRAPS) {
103 guarantee((!Universe::is_bootstrapping() || vmClasses::Object_klass_is_loaded()), "Too-early construction of a flat array klass");
104 assert(UseArrayFlattening, "Flatten array required");
105 assert(MultiArray_lock->holds_lock(THREAD), "must hold lock after bootstrapping");
106 assert(props.is_null_restricted() || !props.is_non_atomic(),
107 "Nullable non-atomic arrays are unsupported");
108
109 InlineKlass* element_klass = InlineKlass::cast(eklass);
110 // If the array is non-atomic, then the element should be one of the following:
111 // a) naturally atomic, so atomicity relaxation has no impact; or
112 // b) explicitly marked as allowing non-atomicity.
113 assert(!props.is_non_atomic() ||
114 (element_klass->is_naturally_atomic(props.is_null_restricted()) ||
115 !element_klass->must_be_atomic()),
116 "Cannot conform to atomicity requirements");
117
118 // Eagerly allocate the direct array supertype.
119 Klass* super_klass = nullptr;
120 Klass* element_super = element_klass->super();
121 if (element_super != nullptr) {
122 // The element type has a direct super. E.g., String[] has direct super of Object[].
123 super_klass = element_klass->array_klass(CHECK_NULL);
124 }
125
126 Symbol* name = create_element_klass_array_name(THREAD, element_klass);
127 ClassLoaderData* loader_data = element_klass->class_loader_data();
128 int size = ArrayKlass::static_size(FlatArrayKlass::header_size());
129 FlatArrayKlass* vak = new (loader_data, size, THREAD) FlatArrayKlass(element_klass, name, props, lk);
130
131 ModuleEntry* module = vak->module();
132 assert(module != nullptr, "No module entry for array");
133 complete_create_array_klass(vak, super_klass, module, CHECK_NULL);
134
135 loader_data->add_class(vak);
136
137 return vak;
138 }
139
140 void FlatArrayKlass::initialize(TRAPS) {
141 element_klass()->initialize(THREAD);
142 }
143
144 void FlatArrayKlass::metaspace_pointers_do(MetaspaceClosure* it) {
145 ObjArrayKlass::metaspace_pointers_do(it);
146 }
147
148 // Oops allocation...
149 flatArrayOop FlatArrayKlass::allocate_instance(int length, TRAPS) {
150 assert(UseArrayFlattening, "Must be enabled");
151 check_array_allocation_length(length, max_elements(), CHECK_NULL);
152 int size = flatArrayOopDesc::object_size(layout_helper(), length);
153 oop array = Universe::heap()->array_allocate(this, size, length, true, CHECK_NULL);
154 return oop_cast<flatArrayOop>(array);
155 }
156
157 oop FlatArrayKlass::multi_allocate(int rank, jint* last_size, TRAPS) {
158 // FlatArrays only have one dimension
159 ShouldNotReachHere();
160 }
161
162 jint FlatArrayKlass::array_layout_helper(InlineKlass* vk, LayoutKind lk) {
163 BasicType etype = T_FLAT_ELEMENT;
164 int esize = log2i_exact(round_up_power_of_2(vk->layout_size_in_bytes(lk)));
165 int hsize = arrayOopDesc::base_offset_in_bytes(etype);
166 bool null_free = !LayoutKindHelper::is_nullable_flat(lk);
167 int lh = Klass::array_layout_helper(_lh_array_tag_flat_value, null_free, hsize, etype, esize);
168
169 assert(lh < (int)_lh_neutral_value, "must look like an array layout");
170 assert(layout_helper_is_array(lh), "correct kind");
171 assert(layout_helper_is_flatArray(lh), "correct kind");
172 assert(!layout_helper_is_typeArray(lh), "correct kind");
173 assert(layout_helper_is_null_free(lh) == null_free, "correct kind");
174 assert(layout_helper_header_size(lh) == hsize, "correct decode");
175 assert(layout_helper_element_type(lh) == etype, "correct decode");
176 assert(layout_helper_log2_element_size(lh) == esize, "correct decode");
177 assert((1 << esize) < BytesPerLong || is_aligned(hsize, HeapWordsPerLong), "unaligned base");
178
179 return lh;
180 }
181
182 size_t FlatArrayKlass::oop_size(oop obj) const {
183 // In this assert, we cannot safely access the Klass* with compact headers,
184 // because size_given_klass() calls oop_size() on objects that might be
185 // concurrently forwarded, which would overwrite the Klass*.
186 // Also, why we need to pass this layout_helper() to flatArrayOop::object_size.
187 assert(UseCompactObjectHeaders || obj->is_flatArray(),"must be an flat array");
188 flatArrayOop array = flatArrayOop(obj);
189 return array->object_size(layout_helper());
190 }
191
192 // For now return the maximum number of array elements that will not exceed:
193 // nof bytes = "max_jint * HeapWord" since the "oopDesc::oop_iterate_size"
194 // returns "int" HeapWords, need fix for JDK-4718400 and JDK-8233189
195 jint FlatArrayKlass::max_elements() const {
196 // Check the max number of heap words limit first (because of int32_t in oopDesc_oop_size() etc)
197 size_t max_size = max_jint;
198 max_size -= (arrayOopDesc::base_offset_in_bytes(T_FLAT_ELEMENT) >> LogHeapWordSize);
199 max_size = align_down(max_size, MinObjAlignment);
200 max_size <<= LogHeapWordSize; // convert to max payload size in bytes
201 max_size >>= layout_helper_log2_element_size(_layout_helper); // divide by element size (in bytes) = max elements
202 // Within int32_t heap words, still can't exceed Java array element limit
203 if (max_size > max_jint) {
204 max_size = max_jint;
205 }
206 assert((max_size >> LogHeapWordSize) <= max_jint, "Overflow");
207 return (jint) max_size;
208 }
209
210 oop FlatArrayKlass::protection_domain() const {
211 return element_klass()->protection_domain();
212 }
213
214 // Temp hack having this here: need to move towards Access API
215 static bool needs_backwards_copy(arrayOop s, int src_pos,
216 arrayOop d, int dst_pos, int length) {
217 return (s == d) && (dst_pos > src_pos) && (dst_pos - src_pos) < length;
218 }
219
220 void FlatArrayKlass::copy_array(arrayOop s, int src_pos,
221 arrayOop d, int dst_pos, int length, TRAPS) {
222
223 assert(s->is_refined_objArray(), "must be ref or flat array");
224
225 // Check destination
226 if (!d->is_refined_objArray()) {
227 THROW(vmSymbols::java_lang_ArrayStoreException());
228 }
229
230 // Check if all offsets and lengths are non negative
231 if (src_pos < 0 || dst_pos < 0 || length < 0) {
232 THROW(vmSymbols::java_lang_ArrayIndexOutOfBoundsException());
233 }
234 // Check if the ranges are valid
235 if ( (((unsigned int) length + (unsigned int) src_pos) > (unsigned int) s->length())
236 || (((unsigned int) length + (unsigned int) dst_pos) > (unsigned int) d->length()) ) {
237 THROW(vmSymbols::java_lang_ArrayIndexOutOfBoundsException());
238 }
239 // Check zero copy
240 if (length == 0)
241 return;
242
243 ObjArrayKlass* sk = ObjArrayKlass::cast(s->klass());
244 ObjArrayKlass* dk = ObjArrayKlass::cast(d->klass());
245 Klass* d_elem_klass = dk->element_klass();
246 Klass* s_elem_klass = sk->element_klass();
247 /**** CMH: compare and contrast impl, re-factor once we find edge cases... ****/
248
249 if (sk->is_flatArray_klass()) {
250 assert(sk == this, "Unexpected call to copy_array");
251 FlatArrayKlass* fsk = FlatArrayKlass::cast(sk);
252 // Check subtype, all src homogeneous, so just once
253 if (!s_elem_klass->is_subtype_of(d_elem_klass)) {
254 THROW(vmSymbols::java_lang_ArrayStoreException());
255 }
256
257 flatArrayOop sa = flatArrayOop(s);
258
259 // flatArray-to-flatArray
260 if (dk->is_flatArray_klass()) {
261 // element types MUST be exact, subtype check would be dangerous
262 if (d_elem_klass != this->element_klass()) {
263 THROW(vmSymbols::java_lang_ArrayStoreException());
264 }
265
266 FlatArrayKlass* fdk = FlatArrayKlass::cast(dk);
267 InlineKlass* vk = InlineKlass::cast(s_elem_klass);
268 flatArrayOop da = flatArrayOop(d);
269
270 // We have already checked that src_pos and dst_pos are valid indices.
271 FlatArrayPayload src_payload(sa, src_pos, fsk);
272 FlatArrayPayload dst_payload(da, dst_pos, fdk);
273
274 if (fsk->layout_kind() == fdk->layout_kind()) {
275 // Because source and destination have the same layout, we do not have
276 // to worry about null checks and atomicity problems and can call the
277 // Access API directly.
278 int index_delta;
279 if (needs_backwards_copy(sa, src_pos, da, dst_pos, length)) {
280 index_delta = -1;
281 src_payload.advance_index(length - 1);
282 dst_payload.advance_index(length - 1);
283 } else {
284 index_delta = 1;
285 }
286
287 for (int i = 0; i < length; i++) {
288 HeapAccess<>::value_copy(src_payload, dst_payload);
289 src_payload.advance_index(index_delta);
290 dst_payload.advance_index(index_delta);
291 }
292 } else {
293 // We need to allocate a buffer object to facilitate the copy between
294 // the different layouts. Keep the payload in a handle so we can reload
295 // the oops.
296 FlatArrayPayload::Handle src_payload_handle = src_payload.make_handle(THREAD);
297 FlatArrayPayload::Handle dst_payload_handle = dst_payload.make_handle(THREAD);
298
299 inlineOop buffer = vk->allocate_instance(CHECK);
300 BufferedValuePayload buf_payload(buffer);
301
302 // Reload the oops from the payload handles.
303 src_payload = src_payload_handle();
304 dst_payload = dst_payload_handle();
305
306 const bool dst_is_null_restricted = !LayoutKindHelper::is_nullable_flat(dst_payload.layout_kind());
307
308 // fsk->layout_kind() != fdk->layout_kind() implies that s != d, which
309 // means that the copy is disjoint and we do not need to worry about
310 // needs_backwards_copy.
311 for (int i = 0; i < length; i++) {
312 // Copy via buffer
313 if (src_payload.is_payload_null() || !src_payload.copy_to(buf_payload)) {
314 // The source payload is null. Nothing to copy.
315 if (dst_is_null_restricted) {
316 // The destination does not support null.
317 THROW(vmSymbols::java_lang_NullPointerException());
318 }
319 } else {
320 dst_payload.copy_from(buf_payload);
321 }
322
323 // Advance to next element
324 src_payload.next_element();
325 dst_payload.next_element();
326 }
327 }
328 } else {
329 // flatArray-to-refArray
330 assert(dk->is_refArray_klass(), "Expected objArray here");
331
332 // Need to allocate each new src elem payload -> dst oop
333 refArrayHandle dh(THREAD, (refArrayOop)d);
334 flatArrayHandle sh(THREAD, sa);
335 for (int i = 0; i < length; i++) {
336 oop o = sh->obj_at(src_pos + i, CHECK);
337 dh->obj_at_put(dst_pos + i, o);
338 }
339 }
340 } else {
341 // refArray-to-flatArray
342 assert(s->is_refArray(), "Expected refArray");
343 assert(d->is_flatArray(), "Expected flatArray");
344 refArrayOop sa = refArrayOop(s);
345 flatArrayOop da = flatArrayOop(d);
346
347 for (int i = 0; i < length; i++) {
348 da->obj_at_put( dst_pos + i, sa->obj_at(src_pos + i), CHECK);
349 }
350 }
351 }
352
353 bool FlatArrayKlass::can_be_primary_super_slow() const {
354 return true;
355 }
356
357 u2 FlatArrayKlass::compute_modifier_flags() const {
358 // The modifier for an flatArray is the same as its element
359 // With the addition of ACC_IDENTITY
360 u2 element_flags = element_klass()->compute_modifier_flags();
361
362 u2 identity_flag = (Arguments::is_valhalla_enabled()) ? JVM_ACC_IDENTITY : 0;
363
364 return (element_flags & (JVM_ACC_PUBLIC | JVM_ACC_PRIVATE | JVM_ACC_PROTECTED))
365 | (identity_flag | JVM_ACC_ABSTRACT | JVM_ACC_FINAL);
366 }
367
368 void FlatArrayKlass::print_on(outputStream* st) const {
369 assert(!is_refArray_klass(), "Unimplemented");
370 ResourceMark rm;
371
372 st->print("Flat Type Array: ");
373 Klass::print_on(st);
374
375 st->print(" - element klass: ");
376 element_klass()->print_value_on(st);
377 st->cr();
378
379 st->print(" - layout kind: %s", LayoutKindHelper::layout_kind_as_string(layout_kind()));
380 st->cr();
381
382 st->print(" - array properties: %s", properties().as_string());
383 st->cr();
384
385 int elem_size = element_byte_size();
386 st->print(" - element size %i ", elem_size);
387 st->print("aligned layout size %i", 1 << layout_helper_log2_element_size(layout_helper()));
388 st->cr();
389 }
390
391 void FlatArrayKlass::print_value_on(outputStream* st) const {
392 assert(is_klass(), "must be klass");
393
394 element_klass()->print_value_on(st);
395 st->print("[]");
396 }
397
398 #ifndef PRODUCT
399 void FlatArrayKlass::oop_print_on(oop obj, outputStream* st) {
400 ArrayKlass::oop_print_on(obj, st);
401 flatArrayOop va = flatArrayOop(obj);
402 oop_print_elements_on(va, st);
403 }
404 #endif //PRODUCT
405
406 void FlatArrayKlass::oop_print_value_on(oop obj, outputStream* st) {
407 assert(obj->is_flatArray(), "must be flatArray");
408 st->print("a ");
409 element_klass()->print_value_on(st);
410 int len = flatArrayOop(obj)->length();
411 st->print("[%d] ", len);
412 obj->print_address_on(st);
413 if (PrintMiscellaneous && (WizardMode || Verbose)) {
414 int lh = layout_helper();
415 st->print("{");
416 for (int i = 0; i < len; i++) {
417 if (i > 4) {
418 st->print("..."); break;
419 }
420 st->print(" " INTPTR_FORMAT, (intptr_t)(void*)flatArrayOop(obj)->value_at_addr(i , lh));
421 }
422 st->print(" }");
423 }
424 }
425
426 void FlatArrayKlass::oop_print_elements_on(flatArrayOop fa, outputStream* st) {
427 InlineKlass* vk = element_klass();
428 int print_len = MIN2(fa->length(), MaxElementPrintSize);
429 for(int index = 0; index < print_len; index++) {
430 int off = (address) fa->value_at_addr(index, layout_helper()) - cast_from_oop<address>(fa);
431 st->print_cr(" - Index %3d offset %3d: ", index, off);
432 oop obj = cast_to_oop((address)fa->value_at_addr(index, layout_helper()) - vk->payload_offset());
433 FieldPrinter print_field(st, obj);
434 vk->do_nonstatic_fields(&print_field);
435 st->cr();
436 }
437 int remaining = fa->length() - print_len;
438 if (remaining > 0) {
439 st->print_cr(" - <%d more elements, increase MaxElementPrintSize to print>", remaining);
440 }
441 }
442
443 // Verification
444 class VerifyElementClosure: public BasicOopIterateClosure {
445 public:
446 virtual void do_oop(oop* p) { VerifyOopClosure::verify_oop.do_oop(p); }
447 virtual void do_oop(narrowOop* p) { VerifyOopClosure::verify_oop.do_oop(p); }
448 };
449
450 void FlatArrayKlass::oop_verify_on(oop obj, outputStream* st) {
451 ObjArrayKlass::oop_verify_on(obj, st);
452 guarantee(obj->is_flatArray(), "must be flatArray");
453
454 if (contains_oops()) {
455 flatArrayOop va = flatArrayOop(obj);
456 VerifyElementClosure ec;
457 va->oop_iterate(&ec);
458 }
459 }
460
461 void FlatArrayKlass::verify_on(outputStream* st) {
462 ArrayKlass::verify_on(st);
463 guarantee(element_klass()->is_inline_klass(), "should be inline type klass");
464 }