1 /*
2 * Copyright (c) 2015, 2025, 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 #include "asm/macroAssembler.hpp"
25 #include "classfile/javaClasses.hpp"
26 #include "gc/z/c2/zBarrierSetC2.hpp"
27 #include "gc/z/zBarrierSet.hpp"
28 #include "gc/z/zBarrierSetAssembler.hpp"
29 #include "gc/z/zBarrierSetRuntime.hpp"
30 #include "opto/arraycopynode.hpp"
31 #include "opto/block.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/graphKit.hpp"
34 #include "opto/machnode.hpp"
35 #include "opto/macro.hpp"
36 #include "opto/memnode.hpp"
37 #include "opto/node.hpp"
38 #include "opto/output.hpp"
39 #include "opto/regalloc.hpp"
40 #include "opto/runtime.hpp"
41 #include "opto/type.hpp"
42 #include "utilities/debug.hpp"
43 #include "utilities/growableArray.hpp"
44 #include "utilities/macros.hpp"
45
46 template<typename K, typename V, size_t TableSize>
47 class ZArenaHashtable : public ResourceObj {
48 class ZArenaHashtableEntry : public ResourceObj {
49 public:
50 ZArenaHashtableEntry* _next;
51 K _key;
52 V _value;
53 };
54
55 static const size_t TableMask = TableSize - 1;
56
57 Arena* _arena;
58 ZArenaHashtableEntry* _table[TableSize];
59
60 public:
61 class Iterator {
62 ZArenaHashtable* _table;
63 ZArenaHashtableEntry* _current_entry;
64 size_t _current_index;
65
66 public:
67 Iterator(ZArenaHashtable* table)
68 : _table(table),
69 _current_entry(table->_table[0]),
70 _current_index(0) {
71 if (_current_entry == nullptr) {
72 next();
73 }
74 }
75
76 bool has_next() { return _current_entry != nullptr; }
77 K key() { return _current_entry->_key; }
78 V value() { return _current_entry->_value; }
79
80 void next() {
81 if (_current_entry != nullptr) {
82 _current_entry = _current_entry->_next;
83 }
84 while (_current_entry == nullptr && ++_current_index < TableSize) {
85 _current_entry = _table->_table[_current_index];
86 }
87 }
88 };
89
90 ZArenaHashtable(Arena* arena)
91 : _arena(arena),
92 _table() {
93 Copy::zero_to_bytes(&_table, sizeof(_table));
94 }
95
96 void add(K key, V value) {
97 ZArenaHashtableEntry* entry = new (_arena) ZArenaHashtableEntry();
98 entry->_key = key;
99 entry->_value = value;
100 entry->_next = _table[key & TableMask];
101 _table[key & TableMask] = entry;
102 }
103
104 V* get(K key) const {
105 for (ZArenaHashtableEntry* e = _table[key & TableMask]; e != nullptr; e = e->_next) {
106 if (e->_key == key) {
107 return &(e->_value);
108 }
109 }
110 return nullptr;
111 }
112
113 Iterator iterator() {
114 return Iterator(this);
115 }
116 };
117
118 typedef ZArenaHashtable<intptr_t, bool, 4> ZOffsetTable;
119
120 class ZBarrierSetC2State : public BarrierSetC2State {
121 private:
122 GrowableArray<ZBarrierStubC2*>* _stubs;
123 int _trampoline_stubs_count;
124 int _stubs_start_offset;
125
126 public:
127 ZBarrierSetC2State(Arena* arena)
128 : BarrierSetC2State(arena),
129 _stubs(new (arena) GrowableArray<ZBarrierStubC2*>(arena, 8, 0, nullptr)),
130 _trampoline_stubs_count(0),
131 _stubs_start_offset(0) {}
132
133 GrowableArray<ZBarrierStubC2*>* stubs() {
134 return _stubs;
135 }
136
137 bool needs_liveness_data(const MachNode* mach) const {
138 // Don't need liveness data for nodes without barriers
139 return mach->barrier_data() != ZBarrierElided;
140 }
141
142 bool needs_livein_data() const {
143 return true;
144 }
145
146 void inc_trampoline_stubs_count() {
147 assert(_trampoline_stubs_count != INT_MAX, "Overflow");
148 ++_trampoline_stubs_count;
149 }
150
151 int trampoline_stubs_count() {
152 return _trampoline_stubs_count;
153 }
154
155 void set_stubs_start_offset(int offset) {
156 _stubs_start_offset = offset;
157 }
158
159 int stubs_start_offset() {
160 return _stubs_start_offset;
161 }
162 };
163
164 static ZBarrierSetC2State* barrier_set_state() {
165 return reinterpret_cast<ZBarrierSetC2State*>(Compile::current()->barrier_set_state());
166 }
167
168 void ZBarrierStubC2::register_stub(ZBarrierStubC2* stub) {
169 if (!Compile::current()->output()->in_scratch_emit_size()) {
170 barrier_set_state()->stubs()->append(stub);
171 }
172 }
173
174 void ZBarrierStubC2::inc_trampoline_stubs_count() {
175 if (!Compile::current()->output()->in_scratch_emit_size()) {
176 barrier_set_state()->inc_trampoline_stubs_count();
177 }
178 }
179
180 int ZBarrierStubC2::trampoline_stubs_count() {
181 return barrier_set_state()->trampoline_stubs_count();
182 }
183
184 int ZBarrierStubC2::stubs_start_offset() {
185 return barrier_set_state()->stubs_start_offset();
186 }
187
188 ZBarrierStubC2::ZBarrierStubC2(const MachNode* node) : BarrierStubC2(node) {}
189
190 ZLoadBarrierStubC2* ZLoadBarrierStubC2::create(const MachNode* node, Address ref_addr, Register ref) {
191 AARCH64_ONLY(fatal("Should use ZLoadBarrierStubC2Aarch64::create"));
192 ZLoadBarrierStubC2* const stub = new (Compile::current()->comp_arena()) ZLoadBarrierStubC2(node, ref_addr, ref);
193 register_stub(stub);
194
195 return stub;
196 }
197
198 ZLoadBarrierStubC2::ZLoadBarrierStubC2(const MachNode* node, Address ref_addr, Register ref)
199 : ZBarrierStubC2(node),
200 _ref_addr(ref_addr),
201 _ref(ref) {
202 assert_different_registers(ref, ref_addr.base());
203 assert_different_registers(ref, ref_addr.index());
204 // The runtime call updates the value of ref, so we should not spill and
205 // reload its outdated value.
206 dont_preserve(ref);
207 }
208
209 Address ZLoadBarrierStubC2::ref_addr() const {
210 return _ref_addr;
211 }
212
213 Register ZLoadBarrierStubC2::ref() const {
214 return _ref;
215 }
216
217 address ZLoadBarrierStubC2::slow_path() const {
218 const uint8_t barrier_data = _node->barrier_data();
219 DecoratorSet decorators = DECORATORS_NONE;
220 if (barrier_data & ZBarrierStrong) {
221 decorators |= ON_STRONG_OOP_REF;
222 }
223 if (barrier_data & ZBarrierWeak) {
224 decorators |= ON_WEAK_OOP_REF;
225 }
226 if (barrier_data & ZBarrierPhantom) {
227 decorators |= ON_PHANTOM_OOP_REF;
228 }
229 if (barrier_data & ZBarrierNoKeepalive) {
230 decorators |= AS_NO_KEEPALIVE;
231 }
232 return ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded_addr(decorators);
233 }
234
235 void ZLoadBarrierStubC2::emit_code(MacroAssembler& masm) {
236 ZBarrierSet::assembler()->generate_c2_load_barrier_stub(&masm, static_cast<ZLoadBarrierStubC2*>(this));
237 }
238
239 ZStoreBarrierStubC2* ZStoreBarrierStubC2::create(const MachNode* node, Address ref_addr, Register new_zaddress, Register new_zpointer, bool is_native, bool is_atomic, bool is_nokeepalive) {
240 AARCH64_ONLY(fatal("Should use ZStoreBarrierStubC2Aarch64::create"));
241 ZStoreBarrierStubC2* const stub = new (Compile::current()->comp_arena()) ZStoreBarrierStubC2(node, ref_addr, new_zaddress, new_zpointer, is_native, is_atomic, is_nokeepalive);
242 register_stub(stub);
243
244 return stub;
245 }
246
247 ZStoreBarrierStubC2::ZStoreBarrierStubC2(const MachNode* node, Address ref_addr, Register new_zaddress, Register new_zpointer,
248 bool is_native, bool is_atomic, bool is_nokeepalive)
249 : ZBarrierStubC2(node),
250 _ref_addr(ref_addr),
251 _new_zaddress(new_zaddress),
252 _new_zpointer(new_zpointer),
253 _is_native(is_native),
254 _is_atomic(is_atomic),
255 _is_nokeepalive(is_nokeepalive) {}
256
257 Address ZStoreBarrierStubC2::ref_addr() const {
258 return _ref_addr;
259 }
260
261 Register ZStoreBarrierStubC2::new_zaddress() const {
262 return _new_zaddress;
263 }
264
265 Register ZStoreBarrierStubC2::new_zpointer() const {
266 return _new_zpointer;
267 }
268
269 bool ZStoreBarrierStubC2::is_native() const {
270 return _is_native;
271 }
272
273 bool ZStoreBarrierStubC2::is_atomic() const {
274 return _is_atomic;
275 }
276
277 bool ZStoreBarrierStubC2::is_nokeepalive() const {
278 return _is_nokeepalive;
279 }
280
281 void ZStoreBarrierStubC2::emit_code(MacroAssembler& masm) {
282 ZBarrierSet::assembler()->generate_c2_store_barrier_stub(&masm, static_cast<ZStoreBarrierStubC2*>(this));
283 }
284
285 uint ZBarrierSetC2::estimated_barrier_size(const Node* node) const {
286 uint8_t barrier_data = MemNode::barrier_data(node);
287 assert(barrier_data != 0, "should be a barrier node");
288 uint uncolor_or_color_size = node->is_Load() ? 1 : 2;
289 if ((barrier_data & ZBarrierElided) != 0) {
290 return uncolor_or_color_size;
291 }
292 // A compare and branch corresponds to approximately four fast-path Ideal
293 // nodes (Cmp, Bool, If, If projection). The slow path (If projection and
294 // runtime call) is excluded since the corresponding code is laid out
295 // separately and does not directly affect performance.
296 return uncolor_or_color_size + 4;
297 }
298
299 void* ZBarrierSetC2::create_barrier_state(Arena* comp_arena) const {
300 return new (comp_arena) ZBarrierSetC2State(comp_arena);
301 }
302
303 void ZBarrierSetC2::late_barrier_analysis() const {
304 compute_liveness_at_stubs();
305 analyze_dominating_barriers();
306 }
307
308 void ZBarrierSetC2::emit_stubs(CodeBuffer& cb) const {
309 MacroAssembler masm(&cb);
310 GrowableArray<ZBarrierStubC2*>* const stubs = barrier_set_state()->stubs();
311 barrier_set_state()->set_stubs_start_offset(masm.offset());
312
313 for (int i = 0; i < stubs->length(); i++) {
314 // Make sure there is enough space in the code buffer
315 if (cb.insts()->maybe_expand_to_ensure_remaining(PhaseOutput::max_inst_gcstub_size()) && cb.blob() == nullptr) {
316 ciEnv::current()->record_failure("CodeCache is full");
317 return;
318 }
319
320 stubs->at(i)->emit_code(masm);
321 }
322
323 masm.flush();
324 }
325
326 int ZBarrierSetC2::estimate_stub_size() const {
327 Compile* const C = Compile::current();
328 BufferBlob* const blob = C->output()->scratch_buffer_blob();
329 GrowableArray<ZBarrierStubC2*>* const stubs = barrier_set_state()->stubs();
330 int size = 0;
331
332 for (int i = 0; i < stubs->length(); i++) {
333 CodeBuffer cb(blob->content_begin(), checked_cast<CodeBuffer::csize_t>((address)C->output()->scratch_locs_memory() - blob->content_begin()));
334 MacroAssembler masm(&cb);
335 stubs->at(i)->emit_code(masm);
336 size += cb.insts_size();
337 }
338
339 return size;
340 }
341
342 static void set_barrier_data(C2Access& access) {
343 if (!ZBarrierSet::barrier_needed(access.decorators(), access.type())) {
344 return;
345 }
346
347 if (access.decorators() & C2_TIGHTLY_COUPLED_ALLOC) {
348 access.set_barrier_data(ZBarrierElided);
349 return;
350 }
351
352 uint8_t barrier_data = 0;
353
354 if (access.decorators() & ON_PHANTOM_OOP_REF) {
355 barrier_data |= ZBarrierPhantom;
356 } else if (access.decorators() & ON_WEAK_OOP_REF) {
357 barrier_data |= ZBarrierWeak;
358 } else {
359 barrier_data |= ZBarrierStrong;
360 }
361
362 if (access.decorators() & IN_NATIVE) {
363 barrier_data |= ZBarrierNative;
364 }
365
366 if (access.decorators() & AS_NO_KEEPALIVE) {
367 barrier_data |= ZBarrierNoKeepalive;
368 }
369
370 access.set_barrier_data(barrier_data);
371 }
372
373 Node* ZBarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue& val) const {
374 set_barrier_data(access);
375 return BarrierSetC2::store_at_resolved(access, val);
376 }
377
378 Node* ZBarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {
379 set_barrier_data(access);
380 return BarrierSetC2::load_at_resolved(access, val_type);
381 }
382
383 Node* ZBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
384 Node* new_val, const Type* val_type) const {
385 set_barrier_data(access);
386 return BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, val_type);
387 }
388
389 Node* ZBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
390 Node* new_val, const Type* value_type) const {
391 set_barrier_data(access);
392 return BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
393 }
394
395 Node* ZBarrierSetC2::atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* val_type) const {
396 set_barrier_data(access);
397 return BarrierSetC2::atomic_xchg_at_resolved(access, new_val, val_type);
398 }
399
400 bool ZBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type,
401 bool is_clone, bool is_clone_instance,
402 ArrayCopyPhase phase) const {
403 if (phase == ArrayCopyPhase::Parsing) {
404 return false;
405 }
406 if (phase == ArrayCopyPhase::Optimization) {
407 return is_clone_instance;
408 }
409 // else ArrayCopyPhase::Expansion
410 return type == T_OBJECT || type == T_ARRAY;
411 }
412
413 #define XTOP LP64_ONLY(COMMA phase->top())
414
415 void ZBarrierSetC2::clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const {
416 Node* const src = ac->in(ArrayCopyNode::Src);
417 const TypeAryPtr* const ary_ptr = src->get_ptr_type()->isa_aryptr();
418
419 if (ac->is_clone_array() && ary_ptr != nullptr) {
420 BasicType bt = ary_ptr->elem()->array_element_basic_type();
421 if (is_reference_type(bt)) {
422 // Clone object array
423 bt = T_OBJECT;
424 } else {
425 // Clone primitive array
426 bt = T_LONG;
427 }
428
429 Node* const ctrl = ac->in(TypeFunc::Control);
430 Node* const mem = ac->in(TypeFunc::Memory);
431 Node* const src = ac->in(ArrayCopyNode::Src);
432 Node* src_offset = ac->in(ArrayCopyNode::SrcPos);
433 Node* const dest = ac->in(ArrayCopyNode::Dest);
434 Node* dest_offset = ac->in(ArrayCopyNode::DestPos);
435 Node* length = ac->in(ArrayCopyNode::Length);
436
437 if (bt == T_OBJECT) {
438 // BarrierSetC2::clone sets the offsets via BarrierSetC2::arraycopy_payload_base_offset
439 // which 8-byte aligns them to allow for word size copies. Make sure the offsets point
440 // to the first element in the array when cloning object arrays. Otherwise, load
441 // barriers are applied to parts of the header. Also adjust the length accordingly.
442 assert(src_offset == dest_offset, "should be equal");
443 const jlong offset = src_offset->get_long();
444 if (offset != arrayOopDesc::base_offset_in_bytes(T_OBJECT)) {
445 assert(!UseCompressedClassPointers || UseCompactObjectHeaders, "should only happen without compressed class pointers");
446 assert((arrayOopDesc::base_offset_in_bytes(T_OBJECT) - offset) == BytesPerLong, "unexpected offset");
447 length = phase->transform_later(new SubLNode(length, phase->longcon(1))); // Size is in longs
448 src_offset = phase->longcon(arrayOopDesc::base_offset_in_bytes(T_OBJECT));
449 dest_offset = src_offset;
450 }
451 }
452 Node* const payload_src = phase->basic_plus_adr(src, src_offset);
453 Node* const payload_dst = phase->basic_plus_adr(dest, dest_offset);
454
455 const char* copyfunc_name = "arraycopy";
456 const address copyfunc_addr = phase->basictype2arraycopy(bt, nullptr, nullptr, true, copyfunc_name, true);
457
458 const TypePtr* const raw_adr_type = TypeRawPtr::BOTTOM;
459 const TypeFunc* const call_type = OptoRuntime::fast_arraycopy_Type();
460
461 Node* const call = phase->make_leaf_call(ctrl, mem, call_type, copyfunc_addr, copyfunc_name, raw_adr_type, payload_src, payload_dst, length XTOP);
462 phase->transform_later(call);
463
464 phase->igvn().replace_node(ac, call);
465 return;
466 }
467
468 // Clone instance or array where 'src' is only known to be an object (ary_ptr
469 // is null). This can happen in bytecode generated dynamically to implement
470 // reflective array clones.
471 clone_in_runtime(phase, ac, ZBarrierSetRuntime::clone_addr(), "ZBarrierSetRuntime::clone");
472 }
473
474 #undef XTOP
475
476 void ZBarrierSetC2::elide_dominated_barrier(MachNode* mach) const {
477 mach->set_barrier_data(ZBarrierElided);
478 }
479
480 void ZBarrierSetC2::analyze_dominating_barriers() const {
481 ResourceMark rm;
482 Compile* const C = Compile::current();
483 PhaseCFG* const cfg = C->cfg();
484
485 Node_List loads;
486 Node_List load_dominators;
487
488 Node_List stores;
489 Node_List store_dominators;
490
491 Node_List atomics;
492 Node_List atomic_dominators;
493
494 // Step 1 - Find accesses and allocations, and track them in lists
495 for (uint i = 0; i < cfg->number_of_blocks(); ++i) {
496 const Block* const block = cfg->get_block(i);
497 for (uint j = 0; j < block->number_of_nodes(); ++j) {
498 Node* const node = block->get_node(j);
499 if (node->is_Phi()) {
500 if (is_allocation(node)) {
501 load_dominators.push(node);
502 store_dominators.push(node);
503 // An allocation can't be considered to "dominate" an atomic operation.
504 // For example a CAS requires the memory location to be store-good.
505 // When you have a dominating store or atomic instruction, that is
506 // indeed ensured to be the case. However, as for allocations, the
507 // initialized memory location could be raw null, which isn't store-good.
508 }
509 continue;
510 } else if (!node->is_Mach()) {
511 continue;
512 }
513
514 MachNode* const mach = node->as_Mach();
515 switch (mach->ideal_Opcode()) {
516 case Op_LoadP:
517 if ((mach->barrier_data() & ZBarrierStrong) != 0 &&
518 (mach->barrier_data() & ZBarrierNoKeepalive) == 0) {
519 loads.push(mach);
520 load_dominators.push(mach);
521 }
522 break;
523 case Op_StoreP:
524 if (mach->barrier_data() != 0) {
525 stores.push(mach);
526 load_dominators.push(mach);
527 store_dominators.push(mach);
528 atomic_dominators.push(mach);
529 }
530 break;
531 case Op_CompareAndExchangeP:
532 case Op_CompareAndSwapP:
533 case Op_GetAndSetP:
534 if (mach->barrier_data() != 0) {
535 atomics.push(mach);
536 load_dominators.push(mach);
537 store_dominators.push(mach);
538 atomic_dominators.push(mach);
539 }
540 break;
541
542 default:
543 break;
544 }
545 }
546 }
547
548 // Step 2 - Find dominating accesses or allocations for each access
549 elide_dominated_barriers(loads, load_dominators);
550 elide_dominated_barriers(stores, store_dominators);
551 elide_dominated_barriers(atomics, atomic_dominators);
552 }
553
554 void ZBarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const {
555 eliminate_gc_barrier_data(node);
556 }
557
558 void ZBarrierSetC2::eliminate_gc_barrier_data(Node* node) const {
559 if (node->is_LoadStore()) {
560 LoadStoreNode* loadstore = node->as_LoadStore();
561 loadstore->set_barrier_data(ZBarrierElided);
562 } else if (node->is_Mem()) {
563 MemNode* mem = node->as_Mem();
564 mem->set_barrier_data(ZBarrierElided);
565 }
566 }
567
568 #ifndef PRODUCT
569 void ZBarrierSetC2::dump_barrier_data(const MachNode* mach, outputStream* st) const {
570 if ((mach->barrier_data() & ZBarrierStrong) != 0) {
571 st->print("strong ");
572 }
573 if ((mach->barrier_data() & ZBarrierWeak) != 0) {
574 st->print("weak ");
575 }
576 if ((mach->barrier_data() & ZBarrierPhantom) != 0) {
577 st->print("phantom ");
578 }
579 if ((mach->barrier_data() & ZBarrierNoKeepalive) != 0) {
580 st->print("nokeepalive ");
581 }
582 if ((mach->barrier_data() & ZBarrierNative) != 0) {
583 st->print("native ");
584 }
585 if ((mach->barrier_data() & ZBarrierElided) != 0) {
586 st->print("elided ");
587 }
588 }
589 #endif // !PRODUCT