1 /*
2 * Copyright (c) 2018, 2023, Red Hat, Inc. 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 "classfile/javaClasses.hpp"
27 #include "gc/shared/barrierSet.hpp"
28 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
29 #include "gc/shenandoah/shenandoahForwarding.hpp"
30 #include "gc/shenandoah/shenandoahHeap.hpp"
31 #include "gc/shenandoah/shenandoahRuntime.hpp"
32 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
33 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
34 #include "gc/shenandoah/c2/shenandoahSupport.hpp"
35 #include "gc/shenandoah/heuristics/shenandoahHeuristics.hpp"
36 #include "opto/arraycopynode.hpp"
37 #include "opto/escape.hpp"
38 #include "opto/graphKit.hpp"
39 #include "opto/idealKit.hpp"
40 #include "opto/macro.hpp"
41 #include "opto/movenode.hpp"
42 #include "opto/narrowptrnode.hpp"
43 #include "opto/rootnode.hpp"
44 #include "opto/runtime.hpp"
45
46 ShenandoahBarrierSetC2* ShenandoahBarrierSetC2::bsc2() {
47 return reinterpret_cast<ShenandoahBarrierSetC2*>(BarrierSet::barrier_set()->barrier_set_c2());
48 }
49
50 ShenandoahBarrierSetC2State::ShenandoahBarrierSetC2State(Arena* comp_arena)
51 : _load_reference_barriers(new (comp_arena) GrowableArray<ShenandoahLoadReferenceBarrierNode*>(comp_arena, 8, 0, nullptr)) {
52 }
53
54 int ShenandoahBarrierSetC2State::load_reference_barriers_count() const {
55 return _load_reference_barriers->length();
56 }
57
58 ShenandoahLoadReferenceBarrierNode* ShenandoahBarrierSetC2State::load_reference_barrier(int idx) const {
59 return _load_reference_barriers->at(idx);
60 }
61
62 void ShenandoahBarrierSetC2State::add_load_reference_barrier(ShenandoahLoadReferenceBarrierNode * n) {
63 assert(!_load_reference_barriers->contains(n), "duplicate entry in barrier list");
64 _load_reference_barriers->append(n);
65 }
66
67 void ShenandoahBarrierSetC2State::remove_load_reference_barrier(ShenandoahLoadReferenceBarrierNode * n) {
68 if (_load_reference_barriers->contains(n)) {
69 _load_reference_barriers->remove(n);
70 }
71 }
72
73 #define __ kit->
74
75 bool ShenandoahBarrierSetC2::satb_can_remove_pre_barrier(GraphKit* kit, PhaseValues* phase, Node* adr,
76 BasicType bt, uint adr_idx) const {
77 intptr_t offset = 0;
78 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
79 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
80
81 if (offset == Type::OffsetBot) {
82 return false; // cannot unalias unless there are precise offsets
83 }
84
85 if (alloc == nullptr) {
86 return false; // No allocation found
87 }
88
89 intptr_t size_in_bytes = type2aelembytes(bt);
90
91 Node* mem = __ memory(adr_idx); // start searching here...
92
93 for (int cnt = 0; cnt < 50; cnt++) {
94
95 if (mem->is_Store()) {
96
97 Node* st_adr = mem->in(MemNode::Address);
98 intptr_t st_offset = 0;
99 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
100
101 if (st_base == nullptr) {
102 break; // inscrutable pointer
103 }
104
105 // Break we have found a store with same base and offset as ours so break
106 if (st_base == base && st_offset == offset) {
107 break;
108 }
109
110 if (st_offset != offset && st_offset != Type::OffsetBot) {
111 const int MAX_STORE = BytesPerLong;
112 if (st_offset >= offset + size_in_bytes ||
113 st_offset <= offset - MAX_STORE ||
114 st_offset <= offset - mem->as_Store()->memory_size()) {
115 // Success: The offsets are provably independent.
116 // (You may ask, why not just test st_offset != offset and be done?
117 // The answer is that stores of different sizes can co-exist
118 // in the same sequence of RawMem effects. We sometimes initialize
119 // a whole 'tile' of array elements with a single jint or jlong.)
120 mem = mem->in(MemNode::Memory);
121 continue; // advance through independent store memory
122 }
123 }
124
125 if (st_base != base
126 && MemNode::detect_ptr_independence(base, alloc, st_base,
127 AllocateNode::Ideal_allocation(st_base),
128 phase)) {
129 // Success: The bases are provably independent.
130 mem = mem->in(MemNode::Memory);
131 continue; // advance through independent store memory
132 }
133 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
134
135 InitializeNode* st_init = mem->in(0)->as_Initialize();
136 AllocateNode* st_alloc = st_init->allocation();
137
138 // Make sure that we are looking at the same allocation site.
139 // The alloc variable is guaranteed to not be null here from earlier check.
140 if (alloc == st_alloc) {
141 // Check that the initialization is storing null so that no previous store
142 // has been moved up and directly write a reference
143 Node* captured_store = st_init->find_captured_store(offset,
144 type2aelembytes(T_OBJECT),
145 phase);
146 if (captured_store == nullptr || captured_store == st_init->zero_memory()) {
147 return true;
148 }
149 }
150 }
151
152 // Unless there is an explicit 'continue', we must bail out here,
153 // because 'mem' is an inscrutable memory state (e.g., a call).
154 break;
155 }
156
157 return false;
158 }
159
160 #undef __
161 #define __ ideal.
162
163 void ShenandoahBarrierSetC2::satb_write_barrier_pre(GraphKit* kit,
164 bool do_load,
165 Node* obj,
166 Node* adr,
167 uint alias_idx,
168 Node* val,
169 const TypeOopPtr* val_type,
170 Node* pre_val,
171 BasicType bt) const {
172 // Some sanity checks
173 // Note: val is unused in this routine.
174
175 if (do_load) {
176 // We need to generate the load of the previous value
177 assert(adr != nullptr, "where are loading from?");
178 assert(pre_val == nullptr, "loaded already?");
179 assert(val_type != nullptr, "need a type");
180
181 if (ReduceInitialCardMarks
182 && satb_can_remove_pre_barrier(kit, &kit->gvn(), adr, bt, alias_idx)) {
183 return;
184 }
185
186 } else {
187 // In this case both val_type and alias_idx are unused.
188 assert(pre_val != nullptr, "must be loaded already");
189 // Nothing to be done if pre_val is null.
190 if (pre_val->bottom_type() == TypePtr::NULL_PTR) return;
191 assert(pre_val->bottom_type()->basic_type() == T_OBJECT, "or we shouldn't be here");
192 }
193 assert(bt == T_OBJECT, "or we shouldn't be here");
194
195 IdealKit ideal(kit, true);
196
197 Node* tls = __ thread(); // ThreadLocalStorage
198
199 Node* no_base = __ top();
200 Node* zero = __ ConI(0);
201 Node* zeroX = __ ConX(0);
202
203 float likely = PROB_LIKELY(0.999);
204 float unlikely = PROB_UNLIKELY(0.999);
205
206 // Offsets into the thread
207 const int index_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset());
208 const int buffer_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
209
210 // Now the actual pointers into the thread
211 Node* buffer_adr = __ AddP(no_base, tls, __ ConX(buffer_offset));
212 Node* index_adr = __ AddP(no_base, tls, __ ConX(index_offset));
213
214 // Now some of the values
215 Node* marking;
216 Node* gc_state = __ AddP(no_base, tls, __ ConX(in_bytes(ShenandoahThreadLocalData::gc_state_offset())));
217 Node* ld = __ load(__ ctrl(), gc_state, TypeInt::BYTE, T_BYTE, Compile::AliasIdxRaw);
218 marking = __ AndI(ld, __ ConI(ShenandoahHeap::MARKING));
219 assert(ShenandoahBarrierC2Support::is_gc_state_load(ld), "Should match the shape");
220
221 // if (!marking)
222 __ if_then(marking, BoolTest::ne, zero, unlikely); {
223 BasicType index_bt = TypeX_X->basic_type();
224 assert(sizeof(size_t) == type2aelembytes(index_bt), "Loading Shenandoah SATBMarkQueue::_index with wrong size.");
225 Node* index = __ load(__ ctrl(), index_adr, TypeX_X, index_bt, Compile::AliasIdxRaw);
226
227 if (do_load) {
228 // load original value
229 // alias_idx correct??
230 pre_val = __ load(__ ctrl(), adr, val_type, bt, alias_idx);
231 }
232
233 // if (pre_val != nullptr)
234 __ if_then(pre_val, BoolTest::ne, kit->null()); {
235 Node* buffer = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw);
236
237 // is the queue for this thread full?
238 __ if_then(index, BoolTest::ne, zeroX, likely); {
239
240 // decrement the index
241 Node* next_index = kit->gvn().transform(new SubXNode(index, __ ConX(sizeof(intptr_t))));
242
243 // Now get the buffer location we will log the previous value into and store it
244 Node *log_addr = __ AddP(no_base, buffer, next_index);
245 __ store(__ ctrl(), log_addr, pre_val, T_OBJECT, Compile::AliasIdxRaw, MemNode::unordered);
246 // update the index
247 __ store(__ ctrl(), index_adr, next_index, index_bt, Compile::AliasIdxRaw, MemNode::unordered);
248
249 } __ else_(); {
250
251 // logging buffer is full, call the runtime
252 const TypeFunc *tf = ShenandoahBarrierSetC2::write_ref_field_pre_Type();
253 __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre), "shenandoah_wb_pre",
254 pre_val, tls);
255 } __ end_if(); // (!index)
256 } __ end_if(); // (pre_val != nullptr)
257 } __ end_if(); // (!marking)
258
259 // Final sync IdealKit and GraphKit.
260 kit->final_sync(ideal);
261
262 if (ShenandoahSATBBarrier && adr != nullptr) {
263 Node* c = kit->control();
264 Node* call = c->in(1)->in(1)->in(1)->in(0);
265 assert(is_shenandoah_wb_pre_call(call), "shenandoah_wb_pre call expected");
266 call->add_req(adr);
267 }
268 }
269
270 bool ShenandoahBarrierSetC2::is_shenandoah_wb_pre_call(Node* call) {
271 return call->is_CallLeaf() &&
272 call->as_CallLeaf()->entry_point() == CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre);
273 }
274
275 bool ShenandoahBarrierSetC2::is_shenandoah_clone_call(Node* call) {
276 return call->is_CallLeaf() &&
277 call->as_CallLeaf()->entry_point() == CAST_FROM_FN_PTR(address, ShenandoahRuntime::clone_barrier);
278 }
279
280 bool ShenandoahBarrierSetC2::is_shenandoah_lrb_call(Node* call) {
281 if (!call->is_CallLeaf()) {
282 return false;
283 }
284
285 address entry_point = call->as_CallLeaf()->entry_point();
286 return (entry_point == CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong)) ||
287 (entry_point == CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_strong_narrow)) ||
288 (entry_point == CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak)) ||
289 (entry_point == CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_weak_narrow)) ||
290 (entry_point == CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_phantom)) ||
291 (entry_point == CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_phantom_narrow));
292 }
293
294 bool ShenandoahBarrierSetC2::is_shenandoah_marking_if(PhaseValues* phase, Node* n) {
295 if (n->Opcode() != Op_If) {
296 return false;
297 }
298
299 Node* bol = n->in(1);
300 assert(bol->is_Bool(), "");
301 Node* cmpx = bol->in(1);
302 if (bol->as_Bool()->_test._test == BoolTest::ne &&
303 cmpx->is_Cmp() && cmpx->in(2) == phase->intcon(0) &&
304 is_shenandoah_state_load(cmpx->in(1)->in(1)) &&
305 cmpx->in(1)->in(2)->is_Con() &&
306 cmpx->in(1)->in(2) == phase->intcon(ShenandoahHeap::MARKING)) {
307 return true;
308 }
309
310 return false;
311 }
312
313 bool ShenandoahBarrierSetC2::is_shenandoah_state_load(Node* n) {
314 if (!n->is_Load()) return false;
315 const int state_offset = in_bytes(ShenandoahThreadLocalData::gc_state_offset());
316 return n->in(2)->is_AddP() && n->in(2)->in(2)->Opcode() == Op_ThreadLocal
317 && n->in(2)->in(3)->is_Con()
318 && n->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == state_offset;
319 }
320
321 void ShenandoahBarrierSetC2::shenandoah_write_barrier_pre(GraphKit* kit,
322 bool do_load,
323 Node* obj,
324 Node* adr,
325 uint alias_idx,
326 Node* val,
327 const TypeOopPtr* val_type,
328 Node* pre_val,
329 BasicType bt) const {
330 if (ShenandoahSATBBarrier) {
331 IdealKit ideal(kit);
332 kit->sync_kit(ideal);
333
334 satb_write_barrier_pre(kit, do_load, obj, adr, alias_idx, val, val_type, pre_val, bt);
335
336 ideal.sync_kit(kit);
337 kit->final_sync(ideal);
338 }
339 }
340
341 // Helper that guards and inserts a pre-barrier.
342 void ShenandoahBarrierSetC2::insert_pre_barrier(GraphKit* kit, Node* base_oop, Node* offset,
343 Node* pre_val, bool need_mem_bar) const {
344 // We could be accessing the referent field of a reference object. If so, when Shenandoah
345 // is enabled, we need to log the value in the referent field in an SATB buffer.
346 // This routine performs some compile time filters and generates suitable
347 // runtime filters that guard the pre-barrier code.
348 // Also add memory barrier for non volatile load from the referent field
349 // to prevent commoning of loads across safepoint.
350
351 // Some compile time checks.
352
353 // If offset is a constant, is it java_lang_ref_Reference::_reference_offset?
354 const TypeX* otype = offset->find_intptr_t_type();
355 if (otype != nullptr && otype->is_con() &&
356 otype->get_con() != java_lang_ref_Reference::referent_offset()) {
357 // Constant offset but not the reference_offset so just return
358 return;
359 }
360
361 // We only need to generate the runtime guards for instances.
362 const TypeOopPtr* btype = base_oop->bottom_type()->isa_oopptr();
363 if (btype != nullptr) {
364 if (btype->isa_aryptr()) {
365 // Array type so nothing to do
366 return;
367 }
368
369 const TypeInstPtr* itype = btype->isa_instptr();
370 if (itype != nullptr) {
371 // Can the klass of base_oop be statically determined to be
372 // _not_ a sub-class of Reference and _not_ Object?
373 ciKlass* klass = itype->instance_klass();
374 if (klass->is_loaded() &&
375 !klass->is_subtype_of(kit->env()->Reference_klass()) &&
376 !kit->env()->Object_klass()->is_subtype_of(klass)) {
377 return;
378 }
379 }
380 }
381
382 // The compile time filters did not reject base_oop/offset so
383 // we need to generate the following runtime filters
384 //
385 // if (offset == java_lang_ref_Reference::_reference_offset) {
386 // if (instance_of(base, java.lang.ref.Reference)) {
387 // pre_barrier(_, pre_val, ...);
388 // }
389 // }
390
391 float likely = PROB_LIKELY( 0.999);
392 float unlikely = PROB_UNLIKELY(0.999);
393
394 IdealKit ideal(kit);
395
396 Node* referent_off = __ ConX(java_lang_ref_Reference::referent_offset());
397
398 __ if_then(offset, BoolTest::eq, referent_off, unlikely); {
399 // Update graphKit memory and control from IdealKit.
400 kit->sync_kit(ideal);
401
402 Node* ref_klass_con = kit->makecon(TypeKlassPtr::make(kit->env()->Reference_klass()));
403 Node* is_instof = kit->gen_instanceof(base_oop, ref_klass_con);
404
405 // Update IdealKit memory and control from graphKit.
406 __ sync_kit(kit);
407
408 Node* one = __ ConI(1);
409 // is_instof == 0 if base_oop == nullptr
410 __ if_then(is_instof, BoolTest::eq, one, unlikely); {
411
412 // Update graphKit from IdeakKit.
413 kit->sync_kit(ideal);
414
415 // Use the pre-barrier to record the value in the referent field
416 satb_write_barrier_pre(kit, false /* do_load */,
417 nullptr /* obj */, nullptr /* adr */, max_juint /* alias_idx */, nullptr /* val */, nullptr /* val_type */,
418 pre_val /* pre_val */,
419 T_OBJECT);
420 if (need_mem_bar) {
421 // Add memory barrier to prevent commoning reads from this field
422 // across safepoint since GC can change its value.
423 kit->insert_mem_bar(Op_MemBarCPUOrder);
424 }
425 // Update IdealKit from graphKit.
426 __ sync_kit(kit);
427
428 } __ end_if(); // _ref_type != ref_none
429 } __ end_if(); // offset == referent_offset
430
431 // Final sync IdealKit and GraphKit.
432 kit->final_sync(ideal);
433 }
434
435 #undef __
436
437 const TypeFunc* ShenandoahBarrierSetC2::write_ref_field_pre_Type() {
438 const Type **fields = TypeTuple::fields(2);
439 fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL; // original field value
440 fields[TypeFunc::Parms+1] = TypeRawPtr::NOTNULL; // thread
441 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields);
442
443 // create result type (range)
444 fields = TypeTuple::fields(0);
445 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+0, fields);
446
447 return TypeFunc::make(domain, range);
448 }
449
450 const TypeFunc* ShenandoahBarrierSetC2::clone_barrier_Type() {
451 const Type **fields = TypeTuple::fields(1);
452 fields[TypeFunc::Parms+0] = TypeOopPtr::NOTNULL; // src oop
453 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+1, fields);
454
455 // create result type (range)
456 fields = TypeTuple::fields(0);
457 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+0, fields);
458
459 return TypeFunc::make(domain, range);
460 }
461
462 const TypeFunc* ShenandoahBarrierSetC2::load_reference_barrier_Type() {
463 const Type **fields = TypeTuple::fields(2);
464 fields[TypeFunc::Parms+0] = TypeOopPtr::BOTTOM; // original field value
465 fields[TypeFunc::Parms+1] = TypeRawPtr::BOTTOM; // original load address
466
467 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields);
468
469 // create result type (range)
470 fields = TypeTuple::fields(1);
471 fields[TypeFunc::Parms+0] = TypeOopPtr::BOTTOM;
472 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+1, fields);
473
474 return TypeFunc::make(domain, range);
475 }
476
477 Node* ShenandoahBarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue& val) const {
478 DecoratorSet decorators = access.decorators();
479
480 const TypePtr* adr_type = access.addr().type();
481 Node* adr = access.addr().node();
482
483 bool no_keepalive = (decorators & AS_NO_KEEPALIVE) != 0;
484
485 if (!access.is_oop()) {
486 return BarrierSetC2::store_at_resolved(access, val);
487 }
488
489 if (no_keepalive) {
490 // No keep-alive means no need for the pre-barrier.
491 return BarrierSetC2::store_at_resolved(access, val);
492 }
493
494 if (access.is_parse_access()) {
495 C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access);
496 GraphKit* kit = parse_access.kit();
497
498 uint adr_idx = kit->C->get_alias_index(adr_type);
499 assert(adr_idx != Compile::AliasIdxTop, "use other store_to_memory factory" );
500 shenandoah_write_barrier_pre(kit, true /* do_load */, /*kit->control(),*/ access.base(), adr, adr_idx, val.node(),
501 static_cast<const TypeOopPtr*>(val.type()), nullptr /* pre_val */, access.type());
502 }
503 return BarrierSetC2::store_at_resolved(access, val);
504 }
505
506 Node* ShenandoahBarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {
507 // 1: non-reference load, no additional barrier is needed
508 if (!access.is_oop()) {
509 return BarrierSetC2::load_at_resolved(access, val_type);
510 }
511
512 Node* load = BarrierSetC2::load_at_resolved(access, val_type);
513 DecoratorSet decorators = access.decorators();
514 BasicType type = access.type();
515
516 // 2: apply LRB if needed
517 if (ShenandoahBarrierSet::need_load_reference_barrier(decorators, type)) {
518 load = new ShenandoahLoadReferenceBarrierNode(nullptr, load, decorators);
519 if (access.is_parse_access()) {
520 load = static_cast<C2ParseAccess &>(access).kit()->gvn().transform(load);
521 } else {
522 load = static_cast<C2OptAccess &>(access).gvn().transform(load);
523 }
524 }
525
526 // 3: apply keep-alive barrier for java.lang.ref.Reference if needed
527 if (ShenandoahBarrierSet::need_keep_alive_barrier(decorators, type)) {
528 Node* top = Compile::current()->top();
529 Node* adr = access.addr().node();
530 Node* offset = adr->is_AddP() ? adr->in(AddPNode::Offset) : top;
531 Node* obj = access.base();
532
533 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;
534 bool on_weak_ref = (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) != 0;
535 bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;
536
537 // If we are reading the value of the referent field of a Reference
538 // object (either by using Unsafe directly or through reflection)
539 // then, if SATB is enabled, we need to record the referent in an
540 // SATB log buffer using the pre-barrier mechanism.
541 // Also we need to add memory barrier to prevent commoning reads
542 // from this field across safepoint since GC can change its value.
543 if (!on_weak_ref || (unknown && (offset == top || obj == top)) || !keep_alive) {
544 return load;
545 }
546
547 assert(access.is_parse_access(), "entry not supported at optimization time");
548 C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access);
549 GraphKit* kit = parse_access.kit();
550 bool mismatched = (decorators & C2_MISMATCHED) != 0;
551 bool is_unordered = (decorators & MO_UNORDERED) != 0;
552 bool in_native = (decorators & IN_NATIVE) != 0;
553 bool need_cpu_mem_bar = !is_unordered || mismatched || in_native;
554
555 if (on_weak_ref) {
556 // Use the pre-barrier to record the value in the referent field
557 satb_write_barrier_pre(kit, false /* do_load */,
558 nullptr /* obj */, nullptr /* adr */, max_juint /* alias_idx */, nullptr /* val */, nullptr /* val_type */,
559 load /* pre_val */, T_OBJECT);
560 // Add memory barrier to prevent commoning reads from this field
561 // across safepoint since GC can change its value.
562 kit->insert_mem_bar(Op_MemBarCPUOrder);
563 } else if (unknown) {
564 // We do not require a mem bar inside pre_barrier if need_mem_bar
565 // is set: the barriers would be emitted by us.
566 insert_pre_barrier(kit, obj, offset, load, !need_cpu_mem_bar);
567 }
568 }
569
570 return load;
571 }
572
573 Node* ShenandoahBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
574 Node* new_val, const Type* value_type) const {
575 GraphKit* kit = access.kit();
576 if (access.is_oop()) {
577 shenandoah_write_barrier_pre(kit, false /* do_load */,
578 nullptr, nullptr, max_juint, nullptr, nullptr,
579 expected_val /* pre_val */, T_OBJECT);
580
581 MemNode::MemOrd mo = access.mem_node_mo();
582 Node* mem = access.memory();
583 Node* adr = access.addr().node();
584 const TypePtr* adr_type = access.addr().type();
585 Node* load_store = nullptr;
586
587 #ifdef _LP64
588 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
589 Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));
590 Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));
591 if (ShenandoahCASBarrier) {
592 load_store = kit->gvn().transform(new ShenandoahCompareAndExchangeNNode(kit->control(), mem, adr, newval_enc, oldval_enc, adr_type, value_type->make_narrowoop(), mo));
593 } else {
594 load_store = kit->gvn().transform(new CompareAndExchangeNNode(kit->control(), mem, adr, newval_enc, oldval_enc, adr_type, value_type->make_narrowoop(), mo));
595 }
596 } else
597 #endif
598 {
599 if (ShenandoahCASBarrier) {
600 load_store = kit->gvn().transform(new ShenandoahCompareAndExchangePNode(kit->control(), mem, adr, new_val, expected_val, adr_type, value_type->is_oopptr(), mo));
601 } else {
602 load_store = kit->gvn().transform(new CompareAndExchangePNode(kit->control(), mem, adr, new_val, expected_val, adr_type, value_type->is_oopptr(), mo));
603 }
604 }
605
606 access.set_raw_access(load_store);
607 pin_atomic_op(access);
608
609 #ifdef _LP64
610 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
611 load_store = kit->gvn().transform(new DecodeNNode(load_store, load_store->get_ptr_type()));
612 }
613 #endif
614 load_store = kit->gvn().transform(new ShenandoahLoadReferenceBarrierNode(nullptr, load_store, access.decorators()));
615 return load_store;
616 }
617 return BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, value_type);
618 }
619
620 Node* ShenandoahBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
621 Node* new_val, const Type* value_type) const {
622 GraphKit* kit = access.kit();
623 if (access.is_oop()) {
624 shenandoah_write_barrier_pre(kit, false /* do_load */,
625 nullptr, nullptr, max_juint, nullptr, nullptr,
626 expected_val /* pre_val */, T_OBJECT);
627 DecoratorSet decorators = access.decorators();
628 MemNode::MemOrd mo = access.mem_node_mo();
629 Node* mem = access.memory();
630 bool is_weak_cas = (decorators & C2_WEAK_CMPXCHG) != 0;
631 Node* load_store = nullptr;
632 Node* adr = access.addr().node();
633 #ifdef _LP64
634 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
635 Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));
636 Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));
637 if (ShenandoahCASBarrier) {
638 if (is_weak_cas) {
639 load_store = kit->gvn().transform(new ShenandoahWeakCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
640 } else {
641 load_store = kit->gvn().transform(new ShenandoahCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
642 }
643 } else {
644 if (is_weak_cas) {
645 load_store = kit->gvn().transform(new WeakCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
646 } else {
647 load_store = kit->gvn().transform(new CompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
648 }
649 }
650 } else
651 #endif
652 {
653 if (ShenandoahCASBarrier) {
654 if (is_weak_cas) {
655 load_store = kit->gvn().transform(new ShenandoahWeakCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
656 } else {
657 load_store = kit->gvn().transform(new ShenandoahCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
658 }
659 } else {
660 if (is_weak_cas) {
661 load_store = kit->gvn().transform(new WeakCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
662 } else {
663 load_store = kit->gvn().transform(new CompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
664 }
665 }
666 }
667 access.set_raw_access(load_store);
668 pin_atomic_op(access);
669 return load_store;
670 }
671 return BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
672 }
673
674 Node* ShenandoahBarrierSetC2::atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* val, const Type* value_type) const {
675 GraphKit* kit = access.kit();
676 Node* result = BarrierSetC2::atomic_xchg_at_resolved(access, val, value_type);
677 if (access.is_oop()) {
678 result = kit->gvn().transform(new ShenandoahLoadReferenceBarrierNode(nullptr, result, access.decorators()));
679 shenandoah_write_barrier_pre(kit, false /* do_load */,
680 nullptr, nullptr, max_juint, nullptr, nullptr,
681 result /* pre_val */, T_OBJECT);
682 }
683 return result;
684 }
685
686
687 bool ShenandoahBarrierSetC2::is_gc_pre_barrier_node(Node* node) const {
688 return is_shenandoah_wb_pre_call(node);
689 }
690
691 bool ShenandoahBarrierSetC2::is_gc_barrier_node(Node* node) const {
692 return (node->Opcode() == Op_ShenandoahLoadReferenceBarrier) ||
693 is_shenandoah_lrb_call(node) ||
694 is_shenandoah_wb_pre_call(node) ||
695 is_shenandoah_clone_call(node);
696 }
697
698 Node* ShenandoahBarrierSetC2::step_over_gc_barrier(Node* c) const {
699 if (c == nullptr) {
700 return c;
701 }
702 if (c->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
703 return c->in(ShenandoahLoadReferenceBarrierNode::ValueIn);
704 }
705 return c;
706 }
707
708 bool ShenandoahBarrierSetC2::expand_barriers(Compile* C, PhaseIterGVN& igvn) const {
709 return !ShenandoahBarrierC2Support::expand(C, igvn);
710 }
711
712 bool ShenandoahBarrierSetC2::optimize_loops(PhaseIdealLoop* phase, LoopOptsMode mode, VectorSet& visited, Node_Stack& nstack, Node_List& worklist) const {
713 if (mode == LoopOptsShenandoahExpand) {
714 assert(UseShenandoahGC, "only for shenandoah");
715 ShenandoahBarrierC2Support::pin_and_expand(phase);
716 return true;
717 } else if (mode == LoopOptsShenandoahPostExpand) {
718 assert(UseShenandoahGC, "only for shenandoah");
719 visited.clear();
720 ShenandoahBarrierC2Support::optimize_after_expansion(visited, nstack, worklist, phase);
721 return true;
722 }
723 return false;
724 }
725
726 bool ShenandoahBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, bool is_clone_instance, ArrayCopyPhase phase) const {
727 bool is_oop = is_reference_type(type);
728 if (!is_oop) {
729 return false;
730 }
731 if (ShenandoahSATBBarrier && tightly_coupled_alloc) {
732 if (phase == Optimization) {
733 return false;
734 }
735 return !is_clone;
736 }
737 return true;
738 }
739
740 bool ShenandoahBarrierSetC2::clone_needs_barrier(Node* src, PhaseGVN& gvn) {
741 const TypeOopPtr* src_type = gvn.type(src)->is_oopptr();
742 if (src_type->isa_instptr() != nullptr) {
743 ciInstanceKlass* ik = src_type->is_instptr()->instance_klass();
744 if ((src_type->klass_is_exact() || !ik->has_subklass()) && !ik->has_injected_fields()) {
745 if (ik->has_object_fields()) {
746 return true;
747 } else {
748 if (!src_type->klass_is_exact()) {
749 Compile::current()->dependencies()->assert_leaf_type(ik);
750 }
751 }
752 } else {
753 return true;
754 }
755 } else if (src_type->isa_aryptr()) {
756 BasicType src_elem = src_type->isa_aryptr()->elem()->array_element_basic_type();
757 if (is_reference_type(src_elem, true)) {
758 return true;
759 }
760 } else {
761 return true;
762 }
763 return false;
764 }
765
766 void ShenandoahBarrierSetC2::clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const {
767 Node* ctrl = ac->in(TypeFunc::Control);
768 Node* mem = ac->in(TypeFunc::Memory);
769 Node* src_base = ac->in(ArrayCopyNode::Src);
770 Node* src_offset = ac->in(ArrayCopyNode::SrcPos);
771 Node* dest_base = ac->in(ArrayCopyNode::Dest);
772 Node* dest_offset = ac->in(ArrayCopyNode::DestPos);
773 Node* length = ac->in(ArrayCopyNode::Length);
774
775 Node* src = phase->basic_plus_adr(src_base, src_offset);
776 Node* dest = phase->basic_plus_adr(dest_base, dest_offset);
777
778 if (ShenandoahCloneBarrier && clone_needs_barrier(src, phase->igvn())) {
779 // Check if heap is has forwarded objects. If it does, we need to call into the special
780 // routine that would fix up source references before we can continue.
781
782 enum { _heap_stable = 1, _heap_unstable, PATH_LIMIT };
783 Node* region = new RegionNode(PATH_LIMIT);
784 Node* mem_phi = new PhiNode(region, Type::MEMORY, TypeRawPtr::BOTTOM);
785
786 Node* thread = phase->transform_later(new ThreadLocalNode());
787 Node* offset = phase->igvn().MakeConX(in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
788 Node* gc_state_addr = phase->transform_later(new AddPNode(phase->C->top(), thread, offset));
789
790 uint gc_state_idx = Compile::AliasIdxRaw;
791 const TypePtr* gc_state_adr_type = nullptr; // debug-mode-only argument
792 debug_only(gc_state_adr_type = phase->C->get_adr_type(gc_state_idx));
793
794 Node* gc_state = phase->transform_later(new LoadBNode(ctrl, mem, gc_state_addr, gc_state_adr_type, TypeInt::BYTE, MemNode::unordered));
795 Node* stable_and = phase->transform_later(new AndINode(gc_state, phase->igvn().intcon(ShenandoahHeap::HAS_FORWARDED)));
796 Node* stable_cmp = phase->transform_later(new CmpINode(stable_and, phase->igvn().zerocon(T_INT)));
797 Node* stable_test = phase->transform_later(new BoolNode(stable_cmp, BoolTest::ne));
798
799 IfNode* stable_iff = phase->transform_later(new IfNode(ctrl, stable_test, PROB_UNLIKELY(0.999), COUNT_UNKNOWN))->as_If();
800 Node* stable_ctrl = phase->transform_later(new IfFalseNode(stable_iff));
801 Node* unstable_ctrl = phase->transform_later(new IfTrueNode(stable_iff));
802
803 // Heap is stable, no need to do anything additional
804 region->init_req(_heap_stable, stable_ctrl);
805 mem_phi->init_req(_heap_stable, mem);
806
807 // Heap is unstable, call into clone barrier stub
808 Node* call = phase->make_leaf_call(unstable_ctrl, mem,
809 ShenandoahBarrierSetC2::clone_barrier_Type(),
810 CAST_FROM_FN_PTR(address, ShenandoahRuntime::clone_barrier),
811 "shenandoah_clone",
812 TypeRawPtr::BOTTOM,
813 src_base);
814 call = phase->transform_later(call);
815
816 ctrl = phase->transform_later(new ProjNode(call, TypeFunc::Control));
817 mem = phase->transform_later(new ProjNode(call, TypeFunc::Memory));
818 region->init_req(_heap_unstable, ctrl);
819 mem_phi->init_req(_heap_unstable, mem);
820
821 // Wire up the actual arraycopy stub now
822 ctrl = phase->transform_later(region);
823 mem = phase->transform_later(mem_phi);
824
825 const char* name = "arraycopy";
826 call = phase->make_leaf_call(ctrl, mem,
827 OptoRuntime::fast_arraycopy_Type(),
828 phase->basictype2arraycopy(T_LONG, nullptr, nullptr, true, name, true),
829 name, TypeRawPtr::BOTTOM,
830 src, dest, length
831 LP64_ONLY(COMMA phase->top()));
832 call = phase->transform_later(call);
833
834 // Hook up the whole thing into the graph
835 phase->igvn().replace_node(ac, call);
836 } else {
837 BarrierSetC2::clone_at_expansion(phase, ac);
838 }
839 }
840
841
842 // Support for macro expanded GC barriers
843 void ShenandoahBarrierSetC2::register_potential_barrier_node(Node* node) const {
844 if (node->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
845 state()->add_load_reference_barrier((ShenandoahLoadReferenceBarrierNode*) node);
846 }
847 }
848
849 void ShenandoahBarrierSetC2::unregister_potential_barrier_node(Node* node) const {
850 if (node->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
851 state()->remove_load_reference_barrier((ShenandoahLoadReferenceBarrierNode*) node);
852 }
853 }
854
855 void ShenandoahBarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* n) const {
856 if (is_shenandoah_wb_pre_call(n)) {
857 shenandoah_eliminate_wb_pre(n, ¯o->igvn());
858 }
859 }
860
861 void ShenandoahBarrierSetC2::shenandoah_eliminate_wb_pre(Node* call, PhaseIterGVN* igvn) const {
862 assert(UseShenandoahGC && is_shenandoah_wb_pre_call(call), "");
863 Node* c = call->as_Call()->proj_out(TypeFunc::Control);
864 c = c->unique_ctrl_out();
865 assert(c->is_Region() && c->req() == 3, "where's the pre barrier control flow?");
866 c = c->unique_ctrl_out();
867 assert(c->is_Region() && c->req() == 3, "where's the pre barrier control flow?");
868 Node* iff = c->in(1)->is_IfProj() ? c->in(1)->in(0) : c->in(2)->in(0);
869 assert(iff->is_If(), "expect test");
870 if (!is_shenandoah_marking_if(igvn, iff)) {
871 c = c->unique_ctrl_out();
872 assert(c->is_Region() && c->req() == 3, "where's the pre barrier control flow?");
873 iff = c->in(1)->is_IfProj() ? c->in(1)->in(0) : c->in(2)->in(0);
874 assert(is_shenandoah_marking_if(igvn, iff), "expect marking test");
875 }
876 Node* cmpx = iff->in(1)->in(1);
877 igvn->replace_node(cmpx, igvn->makecon(TypeInt::CC_EQ));
878 igvn->rehash_node_delayed(call);
879 call->del_req(call->req()-1);
880 }
881
882 void ShenandoahBarrierSetC2::enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {
883 if (node->Opcode() == Op_AddP && ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(node)) {
884 igvn->add_users_to_worklist(node);
885 }
886 }
887
888 void ShenandoahBarrierSetC2::eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {
889 for (uint i = 0; i < useful.size(); i++) {
890 Node* n = useful.at(i);
891 if (n->Opcode() == Op_AddP && ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(n)) {
892 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
893 C->record_for_igvn(n->fast_out(i));
894 }
895 }
896 }
897
898 for (int i = state()->load_reference_barriers_count() - 1; i >= 0; i--) {
899 ShenandoahLoadReferenceBarrierNode* n = state()->load_reference_barrier(i);
900 if (!useful.member(n)) {
901 state()->remove_load_reference_barrier(n);
902 }
903 }
904 }
905
906 void* ShenandoahBarrierSetC2::create_barrier_state(Arena* comp_arena) const {
907 return new(comp_arena) ShenandoahBarrierSetC2State(comp_arena);
908 }
909
910 ShenandoahBarrierSetC2State* ShenandoahBarrierSetC2::state() const {
911 return reinterpret_cast<ShenandoahBarrierSetC2State*>(Compile::current()->barrier_set_state());
912 }
913
914 // If the BarrierSetC2 state has kept macro nodes in its compilation unit state to be
915 // expanded later, then now is the time to do so.
916 bool ShenandoahBarrierSetC2::expand_macro_nodes(PhaseMacroExpand* macro) const { return false; }
917
918 #ifdef ASSERT
919 void ShenandoahBarrierSetC2::verify_gc_barriers(Compile* compile, CompilePhase phase) const {
920 if (ShenandoahVerifyOptoBarriers && phase == BarrierSetC2::BeforeMacroExpand) {
921 ShenandoahBarrierC2Support::verify(Compile::current()->root());
922 } else if (phase == BarrierSetC2::BeforeCodeGen) {
923 // Verify Shenandoah pre-barriers
924 const int gc_state_offset = in_bytes(ShenandoahThreadLocalData::gc_state_offset());
925
926 Unique_Node_List visited;
927 Node_List worklist;
928 // We're going to walk control flow backwards starting from the Root
929 worklist.push(compile->root());
930 while (worklist.size() > 0) {
931 Node *x = worklist.pop();
932 if (x == nullptr || x == compile->top()) {
933 continue;
934 }
935
936 if (visited.member(x)) {
937 continue;
938 } else {
939 visited.push(x);
940 }
941
942 if (x->is_Region()) {
943 for (uint i = 1; i < x->req(); i++) {
944 worklist.push(x->in(i));
945 }
946 } else {
947 worklist.push(x->in(0));
948 // We are looking for the pattern:
949 // /->ThreadLocal
950 // If->Bool->CmpI->LoadB->AddP->ConL(marking_offset)
951 // \->ConI(0)
952 // We want to verify that the If and the LoadB have the same control
953 // See GraphKit::g1_write_barrier_pre()
954 if (x->is_If()) {
955 IfNode *iff = x->as_If();
956 if (iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp()) {
957 CmpNode *cmp = iff->in(1)->in(1)->as_Cmp();
958 if (cmp->Opcode() == Op_CmpI && cmp->in(2)->is_Con() && cmp->in(2)->bottom_type()->is_int()->get_con() == 0
959 && cmp->in(1)->is_Load()) {
960 LoadNode *load = cmp->in(1)->as_Load();
961 if (load->Opcode() == Op_LoadB && load->in(2)->is_AddP() && load->in(2)->in(2)->Opcode() == Op_ThreadLocal
962 && load->in(2)->in(3)->is_Con()
963 && load->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == gc_state_offset) {
964
965 Node *if_ctrl = iff->in(0);
966 Node *load_ctrl = load->in(0);
967
968 if (if_ctrl != load_ctrl) {
969 // Skip possible CProj->NeverBranch in infinite loops
970 if ((if_ctrl->is_Proj() && if_ctrl->Opcode() == Op_CProj)
971 && if_ctrl->in(0)->is_NeverBranch()) {
972 if_ctrl = if_ctrl->in(0)->in(0);
973 }
974 }
975 assert(load_ctrl != nullptr && if_ctrl == load_ctrl, "controls must match");
976 }
977 }
978 }
979 }
980 }
981 }
982 }
983 }
984 #endif
985
986 Node* ShenandoahBarrierSetC2::ideal_node(PhaseGVN* phase, Node* n, bool can_reshape) const {
987 if (is_shenandoah_wb_pre_call(n)) {
988 uint cnt = ShenandoahBarrierSetC2::write_ref_field_pre_Type()->domain()->cnt();
989 if (n->req() > cnt) {
990 Node* addp = n->in(cnt);
991 if (has_only_shenandoah_wb_pre_uses(addp)) {
992 n->del_req(cnt);
993 if (can_reshape) {
994 phase->is_IterGVN()->_worklist.push(addp);
995 }
996 return n;
997 }
998 }
999 }
1000 if (n->Opcode() == Op_CmpP) {
1001 Node* in1 = n->in(1);
1002 Node* in2 = n->in(2);
1003
1004 // If one input is null, then step over the strong LRB barriers on the other input
1005 if (in1->bottom_type() == TypePtr::NULL_PTR &&
1006 !((in2->Opcode() == Op_ShenandoahLoadReferenceBarrier) &&
1007 !ShenandoahBarrierSet::is_strong_access(((ShenandoahLoadReferenceBarrierNode*)in2)->decorators()))) {
1008 in2 = step_over_gc_barrier(in2);
1009 }
1010 if (in2->bottom_type() == TypePtr::NULL_PTR &&
1011 !((in1->Opcode() == Op_ShenandoahLoadReferenceBarrier) &&
1012 !ShenandoahBarrierSet::is_strong_access(((ShenandoahLoadReferenceBarrierNode*)in1)->decorators()))) {
1013 in1 = step_over_gc_barrier(in1);
1014 }
1015
1016 if (in1 != n->in(1)) {
1017 n->set_req_X(1, in1, phase);
1018 assert(in2 == n->in(2), "only one change");
1019 return n;
1020 }
1021 if (in2 != n->in(2)) {
1022 n->set_req_X(2, in2, phase);
1023 return n;
1024 }
1025 } else if (can_reshape &&
1026 n->Opcode() == Op_If &&
1027 ShenandoahBarrierC2Support::is_heap_stable_test(n) &&
1028 n->in(0) != nullptr &&
1029 n->outcnt() == 2) {
1030 Node* dom = n->in(0);
1031 Node* prev_dom = n;
1032 int op = n->Opcode();
1033 int dist = 16;
1034 // Search up the dominator tree for another heap stable test
1035 while (dom->Opcode() != op || // Not same opcode?
1036 !ShenandoahBarrierC2Support::is_heap_stable_test(dom) || // Not same input 1?
1037 prev_dom->in(0) != dom) { // One path of test does not dominate?
1038 if (dist < 0) return nullptr;
1039
1040 dist--;
1041 prev_dom = dom;
1042 dom = IfNode::up_one_dom(dom);
1043 if (!dom) return nullptr;
1044 }
1045
1046 // Check that we did not follow a loop back to ourselves
1047 if (n == dom) {
1048 return nullptr;
1049 }
1050
1051 return n->as_If()->dominated_by(prev_dom, phase->is_IterGVN(), false);
1052 }
1053
1054 return nullptr;
1055 }
1056
1057 bool ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(Node* n) {
1058 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1059 Node* u = n->fast_out(i);
1060 if (!is_shenandoah_wb_pre_call(u)) {
1061 return false;
1062 }
1063 }
1064 return n->outcnt() > 0;
1065 }
1066
1067 bool ShenandoahBarrierSetC2::final_graph_reshaping(Compile* compile, Node* n, uint opcode, Unique_Node_List& dead_nodes) const {
1068 switch (opcode) {
1069 case Op_CallLeaf:
1070 case Op_CallLeafNoFP: {
1071 assert (n->is_Call(), "");
1072 CallNode *call = n->as_Call();
1073 if (ShenandoahBarrierSetC2::is_shenandoah_wb_pre_call(call)) {
1074 uint cnt = ShenandoahBarrierSetC2::write_ref_field_pre_Type()->domain()->cnt();
1075 if (call->req() > cnt) {
1076 assert(call->req() == cnt + 1, "only one extra input");
1077 Node *addp = call->in(cnt);
1078 assert(!ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(addp), "useless address computation?");
1079 call->del_req(cnt);
1080 }
1081 }
1082 return false;
1083 }
1084 case Op_ShenandoahCompareAndSwapP:
1085 case Op_ShenandoahCompareAndSwapN:
1086 case Op_ShenandoahWeakCompareAndSwapN:
1087 case Op_ShenandoahWeakCompareAndSwapP:
1088 case Op_ShenandoahCompareAndExchangeP:
1089 case Op_ShenandoahCompareAndExchangeN:
1090 return true;
1091 case Op_ShenandoahLoadReferenceBarrier:
1092 assert(false, "should have been expanded already");
1093 return true;
1094 default:
1095 return false;
1096 }
1097 }
1098
1099 bool ShenandoahBarrierSetC2::escape_add_to_con_graph(ConnectionGraph* conn_graph, PhaseGVN* gvn, Unique_Node_List* delayed_worklist, Node* n, uint opcode) const {
1100 switch (opcode) {
1101 case Op_ShenandoahCompareAndExchangeP:
1102 case Op_ShenandoahCompareAndExchangeN:
1103 conn_graph->add_objload_to_connection_graph(n, delayed_worklist);
1104 // fallthrough
1105 case Op_ShenandoahWeakCompareAndSwapP:
1106 case Op_ShenandoahWeakCompareAndSwapN:
1107 case Op_ShenandoahCompareAndSwapP:
1108 case Op_ShenandoahCompareAndSwapN:
1109 conn_graph->add_to_congraph_unsafe_access(n, opcode, delayed_worklist);
1110 return true;
1111 case Op_StoreP: {
1112 Node* adr = n->in(MemNode::Address);
1113 const Type* adr_type = gvn->type(adr);
1114 // Pointer stores in Shenandoah barriers looks like unsafe access.
1115 // Ignore such stores to be able scalar replace non-escaping
1116 // allocations.
1117 if (adr_type->isa_rawptr() && adr->is_AddP()) {
1118 Node* base = conn_graph->get_addp_base(adr);
1119 if (base->Opcode() == Op_LoadP &&
1120 base->in(MemNode::Address)->is_AddP()) {
1121 adr = base->in(MemNode::Address);
1122 Node* tls = conn_graph->get_addp_base(adr);
1123 if (tls->Opcode() == Op_ThreadLocal) {
1124 int offs = (int) gvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
1125 const int buf_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
1126 if (offs == buf_offset) {
1127 return true; // Pre barrier previous oop value store.
1128 }
1129 }
1130 }
1131 }
1132 return false;
1133 }
1134 case Op_ShenandoahLoadReferenceBarrier:
1135 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahLoadReferenceBarrierNode::ValueIn), delayed_worklist);
1136 return true;
1137 default:
1138 // Nothing
1139 break;
1140 }
1141 return false;
1142 }
1143
1144 bool ShenandoahBarrierSetC2::escape_add_final_edges(ConnectionGraph* conn_graph, PhaseGVN* gvn, Node* n, uint opcode) const {
1145 switch (opcode) {
1146 case Op_ShenandoahCompareAndExchangeP:
1147 case Op_ShenandoahCompareAndExchangeN: {
1148 Node *adr = n->in(MemNode::Address);
1149 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, adr, nullptr);
1150 // fallthrough
1151 }
1152 case Op_ShenandoahCompareAndSwapP:
1153 case Op_ShenandoahCompareAndSwapN:
1154 case Op_ShenandoahWeakCompareAndSwapP:
1155 case Op_ShenandoahWeakCompareAndSwapN:
1156 return conn_graph->add_final_edges_unsafe_access(n, opcode);
1157 case Op_ShenandoahLoadReferenceBarrier:
1158 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahLoadReferenceBarrierNode::ValueIn), nullptr);
1159 return true;
1160 default:
1161 // Nothing
1162 break;
1163 }
1164 return false;
1165 }
1166
1167 bool ShenandoahBarrierSetC2::escape_has_out_with_unsafe_object(Node* n) const {
1168 return n->has_out_with(Op_ShenandoahCompareAndExchangeP) || n->has_out_with(Op_ShenandoahCompareAndExchangeN) ||
1169 n->has_out_with(Op_ShenandoahCompareAndSwapP, Op_ShenandoahCompareAndSwapN, Op_ShenandoahWeakCompareAndSwapP, Op_ShenandoahWeakCompareAndSwapN);
1170
1171 }
1172
1173 bool ShenandoahBarrierSetC2::matcher_find_shared_post_visit(Matcher* matcher, Node* n, uint opcode) const {
1174 switch (opcode) {
1175 case Op_ShenandoahCompareAndExchangeP:
1176 case Op_ShenandoahCompareAndExchangeN:
1177 case Op_ShenandoahWeakCompareAndSwapP:
1178 case Op_ShenandoahWeakCompareAndSwapN:
1179 case Op_ShenandoahCompareAndSwapP:
1180 case Op_ShenandoahCompareAndSwapN: { // Convert trinary to binary-tree
1181 Node* newval = n->in(MemNode::ValueIn);
1182 Node* oldval = n->in(LoadStoreConditionalNode::ExpectedIn);
1183 Node* pair = new BinaryNode(oldval, newval);
1184 n->set_req(MemNode::ValueIn,pair);
1185 n->del_req(LoadStoreConditionalNode::ExpectedIn);
1186 return true;
1187 }
1188 default:
1189 break;
1190 }
1191 return false;
1192 }
1193
1194 bool ShenandoahBarrierSetC2::matcher_is_store_load_barrier(Node* x, uint xop) const {
1195 return xop == Op_ShenandoahCompareAndExchangeP ||
1196 xop == Op_ShenandoahCompareAndExchangeN ||
1197 xop == Op_ShenandoahWeakCompareAndSwapP ||
1198 xop == Op_ShenandoahWeakCompareAndSwapN ||
1199 xop == Op_ShenandoahCompareAndSwapN ||
1200 xop == Op_ShenandoahCompareAndSwapP;
1201 }