1 /*
2 * Copyright (c) 2018, 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
25 #include "classfile/javaClasses.hpp"
26 #if INCLUDE_CDS
27 #include "code/SCCache.hpp"
28 #endif
29 #include "code/vmreg.inline.hpp"
30 #include "gc/g1/c2/g1BarrierSetC2.hpp"
31 #include "gc/g1/g1BarrierSet.hpp"
32 #include "gc/g1/g1BarrierSetAssembler.hpp"
33 #include "gc/g1/g1BarrierSetRuntime.hpp"
34 #include "gc/g1/g1CardTable.hpp"
35 #include "gc/g1/g1ThreadLocalData.hpp"
36 #include "gc/g1/g1HeapRegion.hpp"
37 #include "opto/arraycopynode.hpp"
38 #include "opto/block.hpp"
39 #include "opto/compile.hpp"
40 #include "opto/escape.hpp"
41 #include "opto/graphKit.hpp"
42 #include "opto/idealKit.hpp"
43 #include "opto/machnode.hpp"
44 #include "opto/macro.hpp"
45 #include "opto/memnode.hpp"
46 #include "opto/node.hpp"
47 #include "opto/output.hpp"
48 #include "opto/regalloc.hpp"
49 #include "opto/rootnode.hpp"
50 #include "opto/runtime.hpp"
51 #include "opto/type.hpp"
52 #include "utilities/growableArray.hpp"
53 #include "utilities/macros.hpp"
54
55 /*
56 * Determine if the G1 pre-barrier can be removed. The pre-barrier is
57 * required by SATB to make sure all objects live at the start of the
58 * marking are kept alive, all reference updates need to any previous
59 * reference stored before writing.
60 *
61 * If the previous value is null there is no need to save the old value.
62 * References that are null are filtered during runtime by the barrier
63 * code to avoid unnecessary queuing.
64 *
65 * However in the case of newly allocated objects it might be possible to
66 * prove that the reference about to be overwritten is null during compile
67 * time and avoid adding the barrier code completely.
68 *
69 * The compiler needs to determine that the object in which a field is about
70 * to be written is newly allocated, and that no prior store to the same field
71 * has happened since the allocation.
72 */
73 bool G1BarrierSetC2::g1_can_remove_pre_barrier(GraphKit* kit,
74 PhaseValues* phase,
75 Node* adr,
76 BasicType bt,
77 uint adr_idx) const {
78 intptr_t offset = 0;
79 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
80 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
81
82 if (offset == Type::OffsetBot) {
83 return false; // Cannot unalias unless there are precise offsets.
84 }
85 if (alloc == nullptr) {
86 return false; // No allocation found.
87 }
88
89 intptr_t size_in_bytes = type2aelembytes(bt);
90 Node* mem = kit->memory(adr_idx); // Start searching here.
91
92 for (int cnt = 0; cnt < 50; cnt++) {
93 if (mem->is_Store()) {
94 Node* st_adr = mem->in(MemNode::Address);
95 intptr_t st_offset = 0;
96 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
97
98 if (st_base == nullptr) {
99 break; // Inscrutable pointer.
100 }
101 if (st_base == base && st_offset == offset) {
102 // We have found a store with same base and offset as ours.
103 break;
104 }
105 if (st_offset != offset && st_offset != Type::OffsetBot) {
106 const int MAX_STORE = BytesPerLong;
107 if (st_offset >= offset + size_in_bytes ||
108 st_offset <= offset - MAX_STORE ||
109 st_offset <= offset - mem->as_Store()->memory_size()) {
110 // Success: The offsets are provably independent.
111 // (You may ask, why not just test st_offset != offset and be done?
112 // The answer is that stores of different sizes can co-exist
113 // in the same sequence of RawMem effects. We sometimes initialize
114 // a whole 'tile' of array elements with a single jint or jlong.)
115 mem = mem->in(MemNode::Memory);
116 continue; // Advance through independent store memory.
117 }
118 }
119 if (st_base != base
120 && MemNode::detect_ptr_independence(base, alloc, st_base,
121 AllocateNode::Ideal_allocation(st_base),
122 phase)) {
123 // Success: the bases are provably independent.
124 mem = mem->in(MemNode::Memory);
125 continue; // Advance through independent store memory.
126 }
127 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
128 InitializeNode* st_init = mem->in(0)->as_Initialize();
129 AllocateNode* st_alloc = st_init->allocation();
130
131 // Make sure that we are looking at the same allocation site.
132 // The alloc variable is guaranteed to not be null here from earlier check.
133 if (alloc == st_alloc) {
134 // Check that the initialization is storing null so that no previous store
135 // has been moved up and directly write a reference.
136 Node* captured_store = st_init->find_captured_store(offset,
137 type2aelembytes(T_OBJECT),
138 phase);
139 if (captured_store == nullptr || captured_store == st_init->zero_memory()) {
140 return true;
141 }
142 }
143 }
144 // Unless there is an explicit 'continue', we must bail out here,
145 // because 'mem' is an inscrutable memory state (e.g., a call).
146 break;
147 }
148 return false;
149 }
150
151 /*
152 * G1, similar to any GC with a Young Generation, requires a way to keep track
153 * of references from Old Generation to Young Generation to make sure all live
154 * objects are found. G1 also requires to keep track of object references
155 * between different regions to enable evacuation of old regions, which is done
156 * as part of mixed collections. References are tracked in remembered sets,
157 * which are continuously updated as references are written to with the help of
158 * the post-barrier.
159 *
160 * To reduce the number of updates to the remembered set, the post-barrier
161 * filters out updates to fields in objects located in the Young Generation, the
162 * same region as the reference, when null is being written, or if the card is
163 * already marked as dirty by an earlier write.
164 *
165 * Under certain circumstances it is possible to avoid generating the
166 * post-barrier completely, if it is possible during compile time to prove the
167 * object is newly allocated and that no safepoint exists between the allocation
168 * and the store. This can be seen as a compile-time version of the
169 * above-mentioned Young Generation filter.
170 *
171 * In the case of a slow allocation, the allocation code must handle the barrier
172 * as part of the allocation if the allocated object is not located in the
173 * nursery; this would happen for humongous objects.
174 */
175 bool G1BarrierSetC2::g1_can_remove_post_barrier(GraphKit* kit,
176 PhaseValues* phase, Node* store_ctrl,
177 Node* adr) const {
178 intptr_t offset = 0;
179 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
180 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
181
182 if (offset == Type::OffsetBot) {
183 return false; // Cannot unalias unless there are precise offsets.
184 }
185 if (alloc == nullptr) {
186 return false; // No allocation found.
187 }
188
189 Node* mem = store_ctrl; // Start search from Store node.
190 if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
191 InitializeNode* st_init = mem->in(0)->as_Initialize();
192 AllocateNode* st_alloc = st_init->allocation();
193 // Make sure we are looking at the same allocation
194 if (alloc == st_alloc) {
195 return true;
196 }
197 }
198
199 return false;
200 }
201
202 Node* G1BarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {
203 DecoratorSet decorators = access.decorators();
204 bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0;
205 bool on_phantom = (decorators & ON_PHANTOM_OOP_REF) != 0;
206 bool no_keepalive = (decorators & AS_NO_KEEPALIVE) != 0;
207 // If we are reading the value of the referent field of a Reference object, we
208 // need to record the referent in an SATB log buffer using the pre-barrier
209 // mechanism. Also we need to add a memory barrier to prevent commoning reads
210 // from this field across safepoints, since GC can change its value.
211 bool need_read_barrier = ((on_weak || on_phantom) && !no_keepalive);
212 if (access.is_oop() && need_read_barrier) {
213 access.set_barrier_data(G1C2BarrierPre);
214 }
215 return CardTableBarrierSetC2::load_at_resolved(access, val_type);
216 }
217
218 void G1BarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const {
219 eliminate_gc_barrier_data(node);
220 }
221
222 void G1BarrierSetC2::eliminate_gc_barrier_data(Node* node) const {
223 if (node->is_LoadStore()) {
224 LoadStoreNode* loadstore = node->as_LoadStore();
225 loadstore->set_barrier_data(0);
226 } else if (node->is_Mem()) {
227 MemNode* mem = node->as_Mem();
228 mem->set_barrier_data(0);
229 }
230 }
231
232 static void refine_barrier_by_new_val_type(const Node* n) {
233 if (n->Opcode() != Op_StoreP &&
234 n->Opcode() != Op_StoreN) {
235 return;
236 }
237 MemNode* store = n->as_Mem();
238 const Node* newval = n->in(MemNode::ValueIn);
239 assert(newval != nullptr, "");
240 const Type* newval_bottom = newval->bottom_type();
241 TypePtr::PTR newval_type = newval_bottom->make_ptr()->ptr();
242 uint8_t barrier_data = store->barrier_data();
243 if (!newval_bottom->isa_oopptr() &&
244 !newval_bottom->isa_narrowoop() &&
245 newval_type != TypePtr::Null) {
246 // newval is neither an OOP nor null, so there is no barrier to refine.
247 assert(barrier_data == 0, "non-OOP stores should have no barrier data");
248 return;
249 }
250 if (barrier_data == 0) {
251 // No barrier to refine.
252 return;
253 }
254 if (newval_type == TypePtr::Null) {
255 // Simply elide post-barrier if writing null.
256 barrier_data &= ~G1C2BarrierPost;
257 barrier_data &= ~G1C2BarrierPostNotNull;
258 } else if (((barrier_data & G1C2BarrierPost) != 0) &&
259 newval_type == TypePtr::NotNull) {
260 // If the post-barrier has not been elided yet (e.g. due to newval being
261 // freshly allocated), mark it as not-null (simplifies barrier tests and
262 // compressed OOPs logic).
263 barrier_data |= G1C2BarrierPostNotNull;
264 }
265 store->set_barrier_data(barrier_data);
266 return;
267 }
268
269 // Refine (not really expand) G1 barriers by looking at the new value type
270 // (whether it is necessarily null or necessarily non-null).
271 bool G1BarrierSetC2::expand_barriers(Compile* C, PhaseIterGVN& igvn) const {
272 ResourceMark rm;
273 VectorSet visited;
274 Node_List worklist;
275 worklist.push(C->root());
276 while (worklist.size() > 0) {
277 Node* n = worklist.pop();
278 if (visited.test_set(n->_idx)) {
279 continue;
280 }
281 refine_barrier_by_new_val_type(n);
282 for (uint j = 0; j < n->req(); j++) {
283 Node* in = n->in(j);
284 if (in != nullptr) {
285 worklist.push(in);
286 }
287 }
288 }
289 return false;
290 }
291
292 uint G1BarrierSetC2::estimated_barrier_size(const Node* node) const {
293 // These Ideal node counts are extracted from the pre-matching Ideal graph
294 // generated when compiling the following method with early barrier expansion:
295 // static void write(MyObject obj1, Object o) {
296 // obj1.o1 = o;
297 // }
298 uint8_t barrier_data = MemNode::barrier_data(node);
299 uint nodes = 0;
300 if ((barrier_data & G1C2BarrierPre) != 0) {
301 nodes += 50;
302 }
303 if ((barrier_data & G1C2BarrierPost) != 0) {
304 nodes += 60;
305 }
306 return nodes;
307 }
308
309 bool G1BarrierSetC2::can_initialize_object(const StoreNode* store) const {
310 assert(store->Opcode() == Op_StoreP || store->Opcode() == Op_StoreN, "OOP store expected");
311 // It is OK to move the store across the object initialization boundary only
312 // if it does not have any barrier, or if it has barriers that can be safely
313 // elided (because of the compensation steps taken on the allocation slow path
314 // when ReduceInitialCardMarks is enabled).
315 return (MemNode::barrier_data(store) == 0) || use_ReduceInitialCardMarks();
316 }
317
318 void G1BarrierSetC2::clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const {
319 if (ac->is_clone_inst() && !use_ReduceInitialCardMarks()) {
320 clone_in_runtime(phase, ac, G1BarrierSetRuntime::clone_addr(), "G1BarrierSetRuntime::clone");
321 return;
322 }
323 BarrierSetC2::clone_at_expansion(phase, ac);
324 }
325
326 Node* G1BarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue& val) const {
327 DecoratorSet decorators = access.decorators();
328 bool anonymous = (decorators & ON_UNKNOWN_OOP_REF) != 0;
329 bool in_heap = (decorators & IN_HEAP) != 0;
330 bool tightly_coupled_alloc = (decorators & C2_TIGHTLY_COUPLED_ALLOC) != 0;
331 bool need_store_barrier = !(tightly_coupled_alloc && use_ReduceInitialCardMarks()) && (in_heap || anonymous);
332 bool no_keepalive = (decorators & AS_NO_KEEPALIVE) != 0;
333 if (access.is_oop() && need_store_barrier) {
334 access.set_barrier_data(get_store_barrier(access));
335 if (tightly_coupled_alloc) {
336 assert(!use_ReduceInitialCardMarks(),
337 "post-barriers are only needed for tightly-coupled initialization stores when ReduceInitialCardMarks is disabled");
338 // Pre-barriers are unnecessary for tightly-coupled initialization stores.
339 access.set_barrier_data(access.barrier_data() & ~G1C2BarrierPre);
340 }
341 }
342 if (no_keepalive) {
343 // No keep-alive means no need for the pre-barrier.
344 access.set_barrier_data(access.barrier_data() & ~G1C2BarrierPre);
345 }
346 return BarrierSetC2::store_at_resolved(access, val);
347 }
348
349 Node* G1BarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
350 Node* new_val, const Type* value_type) const {
351 GraphKit* kit = access.kit();
352 if (!access.is_oop()) {
353 return BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, value_type);
354 }
355 access.set_barrier_data(G1C2BarrierPre | G1C2BarrierPost);
356 return BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, value_type);
357 }
358
359 Node* G1BarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
360 Node* new_val, const Type* value_type) const {
361 GraphKit* kit = access.kit();
362 if (!access.is_oop()) {
363 return BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
364 }
365 access.set_barrier_data(G1C2BarrierPre | G1C2BarrierPost);
366 return BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
367 }
368
369 Node* G1BarrierSetC2::atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* value_type) const {
370 GraphKit* kit = access.kit();
371 if (!access.is_oop()) {
372 return BarrierSetC2::atomic_xchg_at_resolved(access, new_val, value_type);
373 }
374 access.set_barrier_data(G1C2BarrierPre | G1C2BarrierPost);
375 return BarrierSetC2::atomic_xchg_at_resolved(access, new_val, value_type);
376 }
377
378 class G1BarrierSetC2State : public BarrierSetC2State {
379 private:
380 GrowableArray<G1BarrierStubC2*>* _stubs;
381
382 public:
383 G1BarrierSetC2State(Arena* arena)
384 : BarrierSetC2State(arena),
385 _stubs(new (arena) GrowableArray<G1BarrierStubC2*>(arena, 8, 0, nullptr)) {}
386
387 GrowableArray<G1BarrierStubC2*>* stubs() {
388 return _stubs;
389 }
390
391 bool needs_liveness_data(const MachNode* mach) const {
392 return G1PreBarrierStubC2::needs_barrier(mach) ||
393 G1PostBarrierStubC2::needs_barrier(mach);
394 }
395
396 bool needs_livein_data() const {
397 return false;
398 }
399 };
400
401 static G1BarrierSetC2State* barrier_set_state() {
402 return reinterpret_cast<G1BarrierSetC2State*>(Compile::current()->barrier_set_state());
403 }
404
405 G1BarrierStubC2::G1BarrierStubC2(const MachNode* node) : BarrierStubC2(node) {}
406
407 G1PreBarrierStubC2::G1PreBarrierStubC2(const MachNode* node) : G1BarrierStubC2(node) {}
408
409 bool G1PreBarrierStubC2::needs_barrier(const MachNode* node) {
410 return (node->barrier_data() & G1C2BarrierPre) != 0;
411 }
412
413 G1PreBarrierStubC2* G1PreBarrierStubC2::create(const MachNode* node) {
414 G1PreBarrierStubC2* const stub = new (Compile::current()->comp_arena()) G1PreBarrierStubC2(node);
415 if (!Compile::current()->output()->in_scratch_emit_size()) {
416 barrier_set_state()->stubs()->append(stub);
417 }
418 return stub;
419 }
420
421 void G1PreBarrierStubC2::initialize_registers(Register obj, Register pre_val, Register thread, Register tmp1, Register tmp2) {
422 _obj = obj;
423 _pre_val = pre_val;
424 _thread = thread;
425 _tmp1 = tmp1;
426 _tmp2 = tmp2;
427 }
428
429 Register G1PreBarrierStubC2::obj() const {
430 return _obj;
431 }
432
433 Register G1PreBarrierStubC2::pre_val() const {
434 return _pre_val;
435 }
436
437 Register G1PreBarrierStubC2::thread() const {
438 return _thread;
439 }
440
441 Register G1PreBarrierStubC2::tmp1() const {
442 return _tmp1;
443 }
444
445 Register G1PreBarrierStubC2::tmp2() const {
446 return _tmp2;
447 }
448
449 void G1PreBarrierStubC2::emit_code(MacroAssembler& masm) {
450 G1BarrierSetAssembler* bs = static_cast<G1BarrierSetAssembler*>(BarrierSet::barrier_set()->barrier_set_assembler());
451 bs->generate_c2_pre_barrier_stub(&masm, this);
452 }
453
454 G1PostBarrierStubC2::G1PostBarrierStubC2(const MachNode* node) : G1BarrierStubC2(node) {}
455
456 bool G1PostBarrierStubC2::needs_barrier(const MachNode* node) {
457 return (node->barrier_data() & G1C2BarrierPost) != 0;
458 }
459
460 G1PostBarrierStubC2* G1PostBarrierStubC2::create(const MachNode* node) {
461 G1PostBarrierStubC2* const stub = new (Compile::current()->comp_arena()) G1PostBarrierStubC2(node);
462 if (!Compile::current()->output()->in_scratch_emit_size()) {
463 barrier_set_state()->stubs()->append(stub);
464 }
465 return stub;
466 }
467
468 void G1PostBarrierStubC2::initialize_registers(Register thread, Register tmp1, Register tmp2, Register tmp3) {
469 _thread = thread;
470 _tmp1 = tmp1;
471 _tmp2 = tmp2;
472 _tmp3 = tmp3;
473 }
474
475 Register G1PostBarrierStubC2::thread() const {
476 return _thread;
477 }
478
479 Register G1PostBarrierStubC2::tmp1() const {
480 return _tmp1;
481 }
482
483 Register G1PostBarrierStubC2::tmp2() const {
484 return _tmp2;
485 }
486
487 Register G1PostBarrierStubC2::tmp3() const {
488 return _tmp3;
489 }
490
491 void G1PostBarrierStubC2::emit_code(MacroAssembler& masm) {
492 G1BarrierSetAssembler* bs = static_cast<G1BarrierSetAssembler*>(BarrierSet::barrier_set()->barrier_set_assembler());
493 bs->generate_c2_post_barrier_stub(&masm, this);
494 }
495
496 void* G1BarrierSetC2::create_barrier_state(Arena* comp_arena) const {
497 return new (comp_arena) G1BarrierSetC2State(comp_arena);
498 }
499
500 int G1BarrierSetC2::get_store_barrier(C2Access& access) const {
501 if (!access.is_parse_access()) {
502 // Only support for eliding barriers at parse time for now.
503 return G1C2BarrierPre | G1C2BarrierPost;
504 }
505 GraphKit* kit = (static_cast<C2ParseAccess&>(access)).kit();
506 Node* ctl = kit->control();
507 Node* adr = access.addr().node();
508 uint adr_idx = kit->C->get_alias_index(access.addr().type());
509 assert(adr_idx != Compile::AliasIdxTop, "use other store_to_memory factory");
510
511 bool can_remove_pre_barrier = g1_can_remove_pre_barrier(kit, &kit->gvn(), adr, access.type(), adr_idx);
512
513 // We can skip marks on a freshly-allocated object in Eden. Keep this code in
514 // sync with CardTableBarrierSet::on_slowpath_allocation_exit. That routine
515 // informs GC to take appropriate compensating steps, upon a slow-path
516 // allocation, so as to make this card-mark elision safe.
517 // The post-barrier can also be removed if null is written. This case is
518 // handled by G1BarrierSetC2::expand_barriers, which runs at the end of C2's
519 // platform-independent optimizations to exploit stronger type information.
520 bool can_remove_post_barrier = use_ReduceInitialCardMarks() &&
521 ((access.base() == kit->just_allocated_object(ctl)) ||
522 g1_can_remove_post_barrier(kit, &kit->gvn(), ctl, adr));
523
524 int barriers = 0;
525 if (!can_remove_pre_barrier) {
526 barriers |= G1C2BarrierPre;
527 }
528 if (!can_remove_post_barrier) {
529 barriers |= G1C2BarrierPost;
530 }
531
532 return barriers;
533 }
534
535 void G1BarrierSetC2::elide_dominated_barrier(MachNode* mach) const {
536 uint8_t barrier_data = mach->barrier_data();
537 barrier_data &= ~G1C2BarrierPre;
538 if (CardTableBarrierSetC2::use_ReduceInitialCardMarks()) {
539 barrier_data &= ~G1C2BarrierPost;
540 barrier_data &= ~G1C2BarrierPostNotNull;
541 }
542 mach->set_barrier_data(barrier_data);
543 }
544
545 void G1BarrierSetC2::analyze_dominating_barriers() const {
546 ResourceMark rm;
547 PhaseCFG* const cfg = Compile::current()->cfg();
548
549 // Find allocations and memory accesses (stores and atomic operations), and
550 // track them in lists.
551 Node_List accesses;
552 Node_List allocations;
553 for (uint i = 0; i < cfg->number_of_blocks(); ++i) {
554 const Block* const block = cfg->get_block(i);
555 for (uint j = 0; j < block->number_of_nodes(); ++j) {
556 Node* const node = block->get_node(j);
557 if (node->is_Phi()) {
558 if (BarrierSetC2::is_allocation(node)) {
559 allocations.push(node);
560 }
561 continue;
562 } else if (!node->is_Mach()) {
563 continue;
564 }
565
566 MachNode* const mach = node->as_Mach();
567 switch (mach->ideal_Opcode()) {
568 case Op_StoreP:
569 case Op_StoreN:
570 case Op_CompareAndExchangeP:
571 case Op_CompareAndSwapP:
572 case Op_GetAndSetP:
573 case Op_CompareAndExchangeN:
574 case Op_CompareAndSwapN:
575 case Op_GetAndSetN:
576 if (mach->barrier_data() != 0) {
577 accesses.push(mach);
578 }
579 break;
580 default:
581 break;
582 }
583 }
584 }
585
586 // Find dominating allocations for each memory access (store or atomic
587 // operation) and elide barriers if there is no safepoint poll in between.
588 elide_dominated_barriers(accesses, allocations);
589 }
590
591 void G1BarrierSetC2::late_barrier_analysis() const {
592 compute_liveness_at_stubs();
593 analyze_dominating_barriers();
594 }
595
596 void G1BarrierSetC2::emit_stubs(CodeBuffer& cb) const {
597 MacroAssembler masm(&cb);
598 GrowableArray<G1BarrierStubC2*>* const stubs = barrier_set_state()->stubs();
599 for (int i = 0; i < stubs->length(); i++) {
600 // Make sure there is enough space in the code buffer
601 if (cb.insts()->maybe_expand_to_ensure_remaining(PhaseOutput::max_inst_gcstub_size()) && cb.blob() == nullptr) {
602 ciEnv::current()->record_failure("CodeCache is full");
603 return;
604 }
605 stubs->at(i)->emit_code(masm);
606 }
607 masm.flush();
608 }
609
610 #ifndef PRODUCT
611 void G1BarrierSetC2::dump_barrier_data(const MachNode* mach, outputStream* st) const {
612 if ((mach->barrier_data() & G1C2BarrierPre) != 0) {
613 st->print("pre ");
614 }
615 if ((mach->barrier_data() & G1C2BarrierPost) != 0) {
616 st->print("post ");
617 }
618 if ((mach->barrier_data() & G1C2BarrierPostNotNull) != 0) {
619 st->print("notnull ");
620 }
621 }
622 #endif // !PRODUCT