1 /*
2 * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "gc/shenandoah/shenandoahHeap.hpp"
26 #include "gc/shenandoah/shenandoahHeuristics.hpp"
27 #include "gc/shenandoah/shenandoahRuntime.hpp"
28 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
29 #include "gc/shenandoah/c2/shenandoahSupport.hpp"
30 #include "opto/arraycopynode.hpp"
31 #include "opto/escape.hpp"
32 #include "opto/graphKit.hpp"
33 #include "opto/idealKit.hpp"
34 #include "opto/macro.hpp"
35 #include "opto/movenode.hpp"
36 #include "opto/narrowptrnode.hpp"
37 #include "opto/rootnode.hpp"
38
39 ShenandoahBarrierSetC2* ShenandoahBarrierSetC2::bsc2() {
40 return reinterpret_cast<ShenandoahBarrierSetC2*>(BarrierSet::barrier_set()->barrier_set_c2());
41 }
42
43 ShenandoahBarrierSetC2State::ShenandoahBarrierSetC2State(Arena* comp_arena)
44 : _shenandoah_barriers(new (comp_arena) GrowableArray<ShenandoahWriteBarrierNode*>(comp_arena, 8, 0, NULL)) {
45 }
46
47 int ShenandoahBarrierSetC2State::shenandoah_barriers_count() const {
48 return _shenandoah_barriers->length();
49 }
50
51 ShenandoahWriteBarrierNode* ShenandoahBarrierSetC2State::shenandoah_barrier(int idx) const {
52 return _shenandoah_barriers->at(idx);
53 }
54
55 void ShenandoahBarrierSetC2State::add_shenandoah_barrier(ShenandoahWriteBarrierNode * n) {
56 assert(!_shenandoah_barriers->contains(n), "duplicate entry in barrier list");
57 _shenandoah_barriers->append(n);
58 }
59
60 void ShenandoahBarrierSetC2State::remove_shenandoah_barrier(ShenandoahWriteBarrierNode * n) {
61 if (_shenandoah_barriers->contains(n)) {
62 _shenandoah_barriers->remove(n);
63 }
64 }
65
66 #define __ kit->
67
68 Node* ShenandoahBarrierSetC2::shenandoah_read_barrier(GraphKit* kit, Node* obj) const {
69 if (ShenandoahReadBarrier) {
70 obj = shenandoah_read_barrier_impl(kit, obj, false, true, true);
71 }
72 return obj;
73 }
74
75 Node* ShenandoahBarrierSetC2::shenandoah_storeval_barrier(GraphKit* kit, Node* obj) const {
76 if (ShenandoahStoreValEnqueueBarrier) {
77 obj = shenandoah_write_barrier(kit, obj);
78 obj = shenandoah_enqueue_barrier(kit, obj);
79 }
80 if (ShenandoahStoreValReadBarrier) {
81 obj = shenandoah_read_barrier_impl(kit, obj, true, false, false);
82 }
83 return obj;
84 }
85
86 Node* ShenandoahBarrierSetC2::shenandoah_read_barrier_impl(GraphKit* kit, Node* obj, bool use_ctrl, bool use_mem, bool allow_fromspace) const {
87 const Type* obj_type = obj->bottom_type();
88 if (obj_type->higher_equal(TypePtr::NULL_PTR)) {
89 return obj;
90 }
91 const TypePtr* adr_type = ShenandoahBarrierNode::brooks_pointer_type(obj_type);
92 Node* mem = use_mem ? __ memory(adr_type) : __ immutable_memory();
93
94 if (! ShenandoahBarrierNode::needs_barrier(&__ gvn(), NULL, obj, mem, allow_fromspace)) {
95 // We know it is null, no barrier needed.
96 return obj;
97 }
98
99 if (obj_type->meet(TypePtr::NULL_PTR) == obj_type->remove_speculative()) {
100
101 // We don't know if it's null or not. Need null-check.
102 enum { _not_null_path = 1, _null_path, PATH_LIMIT };
103 RegionNode* region = new RegionNode(PATH_LIMIT);
104 Node* phi = new PhiNode(region, obj_type);
105 Node* null_ctrl = __ top();
106 Node* not_null_obj = __ null_check_oop(obj, &null_ctrl);
107
108 region->init_req(_null_path, null_ctrl);
109 phi ->init_req(_null_path, __ zerocon(T_OBJECT));
110
111 Node* ctrl = use_ctrl ? __ control() : NULL;
112 ShenandoahReadBarrierNode* rb = new ShenandoahReadBarrierNode(ctrl, mem, not_null_obj, allow_fromspace);
113 Node* n = __ gvn().transform(rb);
114
115 region->init_req(_not_null_path, __ control());
116 phi ->init_req(_not_null_path, n);
117
118 __ set_control(__ gvn().transform(region));
119 __ record_for_igvn(region);
120 return __ gvn().transform(phi);
121
122 } else {
123 // We know it is not null. Simple barrier is sufficient.
124 Node* ctrl = use_ctrl ? __ control() : NULL;
125 ShenandoahReadBarrierNode* rb = new ShenandoahReadBarrierNode(ctrl, mem, obj, allow_fromspace);
126 Node* n = __ gvn().transform(rb);
127 __ record_for_igvn(n);
128 return n;
129 }
130 }
131
132 Node* ShenandoahBarrierSetC2::shenandoah_write_barrier_helper(GraphKit* kit, Node* obj, const TypePtr* adr_type) const {
133 ShenandoahWriteBarrierNode* wb = new ShenandoahWriteBarrierNode(kit->C, kit->control(), kit->memory(adr_type), obj);
134 Node* n = __ gvn().transform(wb);
135 if (n == wb) { // New barrier needs memory projection.
136 Node* proj = __ gvn().transform(new ShenandoahWBMemProjNode(n));
137 __ set_memory(proj, adr_type);
138 }
139 return n;
140 }
141
142 Node* ShenandoahBarrierSetC2::shenandoah_write_barrier(GraphKit* kit, Node* obj) const {
143 if (ShenandoahWriteBarrier) {
144 obj = shenandoah_write_barrier_impl(kit, obj);
145 }
146 return obj;
147 }
148
149 Node* ShenandoahBarrierSetC2::shenandoah_write_barrier_impl(GraphKit* kit, Node* obj) const {
150 if (! ShenandoahBarrierNode::needs_barrier(&__ gvn(), NULL, obj, NULL, true)) {
151 return obj;
152 }
153 const Type* obj_type = obj->bottom_type();
154 const TypePtr* adr_type = ShenandoahBarrierNode::brooks_pointer_type(obj_type);
155 Node* n = shenandoah_write_barrier_helper(kit, obj, adr_type);
156 __ record_for_igvn(n);
157 return n;
158 }
159
160 bool ShenandoahBarrierSetC2::satb_can_remove_pre_barrier(GraphKit* kit, PhaseTransform* phase, Node* adr,
161 BasicType bt, uint adr_idx) const {
162 intptr_t offset = 0;
163 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
164 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
165
166 if (offset == Type::OffsetBot) {
167 return false; // cannot unalias unless there are precise offsets
168 }
169
170 if (alloc == NULL) {
171 return false; // No allocation found
172 }
173
174 intptr_t size_in_bytes = type2aelembytes(bt);
175
176 Node* mem = __ memory(adr_idx); // start searching here...
177
178 for (int cnt = 0; cnt < 50; cnt++) {
179
180 if (mem->is_Store()) {
181
182 Node* st_adr = mem->in(MemNode::Address);
183 intptr_t st_offset = 0;
184 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
185
186 if (st_base == NULL) {
187 break; // inscrutable pointer
188 }
189
190 // Break we have found a store with same base and offset as ours so break
191 if (st_base == base && st_offset == offset) {
192 break;
193 }
194
195 if (st_offset != offset && st_offset != Type::OffsetBot) {
196 const int MAX_STORE = BytesPerLong;
197 if (st_offset >= offset + size_in_bytes ||
198 st_offset <= offset - MAX_STORE ||
199 st_offset <= offset - mem->as_Store()->memory_size()) {
200 // Success: The offsets are provably independent.
201 // (You may ask, why not just test st_offset != offset and be done?
202 // The answer is that stores of different sizes can co-exist
203 // in the same sequence of RawMem effects. We sometimes initialize
204 // a whole 'tile' of array elements with a single jint or jlong.)
205 mem = mem->in(MemNode::Memory);
206 continue; // advance through independent store memory
207 }
208 }
209
210 if (st_base != base
211 && MemNode::detect_ptr_independence(base, alloc, st_base,
212 AllocateNode::Ideal_allocation(st_base, phase),
213 phase)) {
214 // Success: The bases are provably independent.
215 mem = mem->in(MemNode::Memory);
216 continue; // advance through independent store memory
217 }
218 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
219
220 InitializeNode* st_init = mem->in(0)->as_Initialize();
221 AllocateNode* st_alloc = st_init->allocation();
222
223 // Make sure that we are looking at the same allocation site.
224 // The alloc variable is guaranteed to not be null here from earlier check.
225 if (alloc == st_alloc) {
226 // Check that the initialization is storing NULL so that no previous store
227 // has been moved up and directly write a reference
228 Node* captured_store = st_init->find_captured_store(offset,
229 type2aelembytes(T_OBJECT),
230 phase);
231 if (captured_store == NULL || captured_store == st_init->zero_memory()) {
232 return true;
233 }
234 }
235 }
236
237 // Unless there is an explicit 'continue', we must bail out here,
238 // because 'mem' is an inscrutable memory state (e.g., a call).
239 break;
240 }
241
242 return false;
243 }
244
245 #undef __
246 #define __ ideal.
247
248 void ShenandoahBarrierSetC2::satb_write_barrier_pre(GraphKit* kit,
249 bool do_load,
250 Node* obj,
251 Node* adr,
252 uint alias_idx,
253 Node* val,
254 const TypeOopPtr* val_type,
255 Node* pre_val,
256 BasicType bt) const {
257 // Some sanity checks
258 // Note: val is unused in this routine.
259
260 if (do_load) {
261 // We need to generate the load of the previous value
262 assert(obj != NULL, "must have a base");
263 assert(adr != NULL, "where are loading from?");
264 assert(pre_val == NULL, "loaded already?");
265 assert(val_type != NULL, "need a type");
266
267 if (ReduceInitialCardMarks
268 && satb_can_remove_pre_barrier(kit, &kit->gvn(), adr, bt, alias_idx)) {
269 return;
270 }
271
272 } else {
273 // In this case both val_type and alias_idx are unused.
274 assert(pre_val != NULL, "must be loaded already");
275 // Nothing to be done if pre_val is null.
276 if (pre_val->bottom_type() == TypePtr::NULL_PTR) return;
277 assert(pre_val->bottom_type()->basic_type() == T_OBJECT, "or we shouldn't be here");
278 }
279 assert(bt == T_OBJECT, "or we shouldn't be here");
280
281 IdealKit ideal(kit, true);
282
283 Node* tls = __ thread(); // ThreadLocalStorage
284
285 Node* no_base = __ top();
286 Node* zero = __ ConI(0);
287 Node* zeroX = __ ConX(0);
288
289 float likely = PROB_LIKELY(0.999);
290 float unlikely = PROB_UNLIKELY(0.999);
291
292 // Offsets into the thread
293 const int index_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset());
294 const int buffer_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
295
296 // Now the actual pointers into the thread
297 Node* buffer_adr = __ AddP(no_base, tls, __ ConX(buffer_offset));
298 Node* index_adr = __ AddP(no_base, tls, __ ConX(index_offset));
299
300 // Now some of the values
301 Node* marking;
302 Node* gc_state = __ AddP(no_base, tls, __ ConX(in_bytes(ShenandoahThreadLocalData::gc_state_offset())));
303 Node* ld = __ load(__ ctrl(), gc_state, TypeInt::BYTE, T_BYTE, Compile::AliasIdxRaw);
304 marking = __ AndI(ld, __ ConI(ShenandoahHeap::MARKING));
305 assert(ShenandoahWriteBarrierNode::is_gc_state_load(ld), "Should match the shape");
306
307 // if (!marking)
308 __ if_then(marking, BoolTest::ne, zero, unlikely); {
309 BasicType index_bt = TypeX_X->basic_type();
310 assert(sizeof(size_t) == type2aelembytes(index_bt), "Loading G1 SATBMarkQueue::_index with wrong size.");
311 Node* index = __ load(__ ctrl(), index_adr, TypeX_X, index_bt, Compile::AliasIdxRaw);
312
313 if (do_load) {
314 // load original value
315 // alias_idx correct??
316 pre_val = __ load(__ ctrl(), adr, val_type, bt, alias_idx);
317 }
318
319 // if (pre_val != NULL)
320 __ if_then(pre_val, BoolTest::ne, kit->null()); {
321 Node* buffer = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw);
322
323 // is the queue for this thread full?
324 __ if_then(index, BoolTest::ne, zeroX, likely); {
325
326 // decrement the index
327 Node* next_index = kit->gvn().transform(new SubXNode(index, __ ConX(sizeof(intptr_t))));
328
329 // Now get the buffer location we will log the previous value into and store it
330 Node *log_addr = __ AddP(no_base, buffer, next_index);
331 __ store(__ ctrl(), log_addr, pre_val, T_OBJECT, Compile::AliasIdxRaw, MemNode::unordered);
332 // update the index
333 __ store(__ ctrl(), index_adr, next_index, index_bt, Compile::AliasIdxRaw, MemNode::unordered);
334
335 } __ else_(); {
336
337 // logging buffer is full, call the runtime
338 const TypeFunc *tf = ShenandoahBarrierSetC2::write_ref_field_pre_entry_Type();
339 __ make_leaf_call(tf, CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), "shenandoah_wb_pre", pre_val, tls);
340 } __ end_if(); // (!index)
341 } __ end_if(); // (pre_val != NULL)
342 } __ end_if(); // (!marking)
343
344 // Final sync IdealKit and GraphKit.
345 kit->final_sync(ideal);
346
347 if (ShenandoahSATBBarrier && adr != NULL) {
348 Node* c = kit->control();
349 Node* call = c->in(1)->in(1)->in(1)->in(0);
350 assert(is_shenandoah_wb_pre_call(call), "shenandoah_wb_pre call expected");
351 call->add_req(adr);
352 }
353 }
354
355 bool ShenandoahBarrierSetC2::is_shenandoah_wb_pre_call(Node* call) {
356 return call->is_CallLeaf() &&
357 call->as_CallLeaf()->entry_point() == CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry);
358 }
359
360 bool ShenandoahBarrierSetC2::is_shenandoah_wb_call(Node* call) {
361 return call->is_CallLeaf() &&
362 call->as_CallLeaf()->entry_point() == CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_barrier_JRT);
363 }
364
365 bool ShenandoahBarrierSetC2::is_shenandoah_marking_if(PhaseTransform *phase, Node* n) {
366 if (n->Opcode() != Op_If) {
367 return false;
368 }
369
370 Node* bol = n->in(1);
371 assert(bol->is_Bool(), "");
372 Node* cmpx = bol->in(1);
373 if (bol->as_Bool()->_test._test == BoolTest::ne &&
374 cmpx->is_Cmp() && cmpx->in(2) == phase->intcon(0) &&
375 is_shenandoah_state_load(cmpx->in(1)->in(1)) &&
376 cmpx->in(1)->in(2)->is_Con() &&
377 cmpx->in(1)->in(2) == phase->intcon(ShenandoahHeap::MARKING)) {
378 return true;
379 }
380
381 return false;
382 }
383
384 bool ShenandoahBarrierSetC2::is_shenandoah_state_load(Node* n) {
385 if (!n->is_Load()) return false;
386 const int state_offset = in_bytes(ShenandoahThreadLocalData::gc_state_offset());
387 return n->in(2)->is_AddP() && n->in(2)->in(2)->Opcode() == Op_ThreadLocal
388 && n->in(2)->in(3)->is_Con()
389 && n->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == state_offset;
390 }
391
392 void ShenandoahBarrierSetC2::shenandoah_write_barrier_pre(GraphKit* kit,
393 bool do_load,
394 Node* obj,
395 Node* adr,
396 uint alias_idx,
397 Node* val,
398 const TypeOopPtr* val_type,
399 Node* pre_val,
400 BasicType bt) const {
401 if (ShenandoahSATBBarrier) {
402 IdealKit ideal(kit);
403 kit->sync_kit(ideal);
404
405 satb_write_barrier_pre(kit, do_load, obj, adr, alias_idx, val, val_type, pre_val, bt);
406
407 ideal.sync_kit(kit);
408 kit->final_sync(ideal);
409 }
410 }
411
412 Node* ShenandoahBarrierSetC2::shenandoah_enqueue_barrier(GraphKit* kit, Node* pre_val) const {
413 return kit->gvn().transform(new ShenandoahEnqueueBarrierNode(pre_val));
414 }
415
416 // Helper that guards and inserts a pre-barrier.
417 void ShenandoahBarrierSetC2::insert_pre_barrier(GraphKit* kit, Node* base_oop, Node* offset,
418 Node* pre_val, bool need_mem_bar) const {
419 // We could be accessing the referent field of a reference object. If so, when G1
420 // is enabled, we need to log the value in the referent field in an SATB buffer.
421 // This routine performs some compile time filters and generates suitable
422 // runtime filters that guard the pre-barrier code.
423 // Also add memory barrier for non volatile load from the referent field
424 // to prevent commoning of loads across safepoint.
425
426 // Some compile time checks.
427
428 // If offset is a constant, is it java_lang_ref_Reference::_reference_offset?
429 const TypeX* otype = offset->find_intptr_t_type();
430 if (otype != NULL && otype->is_con() &&
431 otype->get_con() != java_lang_ref_Reference::referent_offset) {
432 // Constant offset but not the reference_offset so just return
433 return;
434 }
435
436 // We only need to generate the runtime guards for instances.
437 const TypeOopPtr* btype = base_oop->bottom_type()->isa_oopptr();
438 if (btype != NULL) {
439 if (btype->isa_aryptr()) {
440 // Array type so nothing to do
441 return;
442 }
443
444 const TypeInstPtr* itype = btype->isa_instptr();
445 if (itype != NULL) {
446 // Can the klass of base_oop be statically determined to be
447 // _not_ a sub-class of Reference and _not_ Object?
448 ciKlass* klass = itype->klass();
449 if ( klass->is_loaded() &&
450 !klass->is_subtype_of(kit->env()->Reference_klass()) &&
451 !kit->env()->Object_klass()->is_subtype_of(klass)) {
452 return;
453 }
454 }
455 }
456
457 // The compile time filters did not reject base_oop/offset so
458 // we need to generate the following runtime filters
459 //
460 // if (offset == java_lang_ref_Reference::_reference_offset) {
461 // if (instance_of(base, java.lang.ref.Reference)) {
462 // pre_barrier(_, pre_val, ...);
463 // }
464 // }
465
466 float likely = PROB_LIKELY( 0.999);
467 float unlikely = PROB_UNLIKELY(0.999);
468
469 IdealKit ideal(kit);
470
471 Node* referent_off = __ ConX(java_lang_ref_Reference::referent_offset);
472
473 __ if_then(offset, BoolTest::eq, referent_off, unlikely); {
474 // Update graphKit memory and control from IdealKit.
475 kit->sync_kit(ideal);
476
477 Node* ref_klass_con = kit->makecon(TypeKlassPtr::make(kit->env()->Reference_klass()));
478 Node* is_instof = kit->gen_instanceof(base_oop, ref_klass_con);
479
480 // Update IdealKit memory and control from graphKit.
481 __ sync_kit(kit);
482
483 Node* one = __ ConI(1);
484 // is_instof == 0 if base_oop == NULL
485 __ if_then(is_instof, BoolTest::eq, one, unlikely); {
486
487 // Update graphKit from IdeakKit.
488 kit->sync_kit(ideal);
489
490 // Use the pre-barrier to record the value in the referent field
491 satb_write_barrier_pre(kit, false /* do_load */,
492 NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */,
493 pre_val /* pre_val */,
494 T_OBJECT);
495 if (need_mem_bar) {
496 // Add memory barrier to prevent commoning reads from this field
497 // across safepoint since GC can change its value.
498 kit->insert_mem_bar(Op_MemBarCPUOrder);
499 }
500 // Update IdealKit from graphKit.
501 __ sync_kit(kit);
502
503 } __ end_if(); // _ref_type != ref_none
504 } __ end_if(); // offset == referent_offset
505
506 // Final sync IdealKit and GraphKit.
507 kit->final_sync(ideal);
508 }
509
510 #undef __
511
512 const TypeFunc* ShenandoahBarrierSetC2::write_ref_field_pre_entry_Type() {
513 const Type **fields = TypeTuple::fields(2);
514 fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL; // original field value
515 fields[TypeFunc::Parms+1] = TypeRawPtr::NOTNULL; // thread
516 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields);
517
518 // create result type (range)
519 fields = TypeTuple::fields(0);
520 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+0, fields);
521
522 return TypeFunc::make(domain, range);
523 }
524
525 const TypeFunc* ShenandoahBarrierSetC2::shenandoah_clone_barrier_Type() {
526 const Type **fields = TypeTuple::fields(1);
527 fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL; // original field value
528 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+1, fields);
529
530 // create result type (range)
531 fields = TypeTuple::fields(0);
532 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+0, fields);
533
534 return TypeFunc::make(domain, range);
535 }
536
537 const TypeFunc* ShenandoahBarrierSetC2::shenandoah_write_barrier_Type() {
538 const Type **fields = TypeTuple::fields(1);
539 fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL; // original field value
540 const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+1, fields);
541
542 // create result type (range)
543 fields = TypeTuple::fields(1);
544 fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL;
545 const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+1, fields);
546
547 return TypeFunc::make(domain, range);
548 }
549
550 void ShenandoahBarrierSetC2::resolve_address(C2Access& access) const {
551 const TypePtr* adr_type = access.addr().type();
552
553 if ((access.decorators() & IN_NATIVE) == 0 && (adr_type->isa_instptr() || adr_type->isa_aryptr())) {
554 int off = adr_type->is_ptr()->offset();
555 int base_off = adr_type->isa_instptr() ? instanceOopDesc::base_offset_in_bytes() :
556 arrayOopDesc::base_offset_in_bytes(adr_type->is_aryptr()->elem()->array_element_basic_type());
557 assert(off != Type::OffsetTop, "unexpected offset");
558 if (off == Type::OffsetBot || off >= base_off) {
559 DecoratorSet decorators = access.decorators();
560 bool is_write = (decorators & C2_WRITE_ACCESS) != 0;
561 GraphKit* kit = NULL;
562 if (access.is_parse_access()) {
563 C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access);
564 kit = parse_access.kit();
565 }
566 Node* adr = access.addr().node();
567 assert(adr->is_AddP(), "unexpected address shape");
568 Node* base = adr->in(AddPNode::Base);
569
570 if (is_write) {
571 if (kit != NULL) {
572 base = shenandoah_write_barrier(kit, base);
573 } else {
574 assert(access.is_opt_access(), "either parse or opt access");
575 assert((access.decorators() & C2_ARRAY_COPY) != 0, "can be skipped for clone");
576 }
577 } else {
578 if (adr_type->isa_instptr()) {
579 Compile* C = access.gvn().C;
580 ciField* field = C->alias_type(adr_type)->field();
581
582 // Insert read barrier for Shenandoah.
583 if (field != NULL &&
584 ((ShenandoahOptimizeStaticFinals && field->is_static() && field->is_final()) ||
585 (ShenandoahOptimizeInstanceFinals && !field->is_static() && field->is_final()) ||
586 (ShenandoahOptimizeStableFinals && field->is_stable()))) {
587 // Skip the barrier for special fields
588 } else {
589 if (kit != NULL) {
590 base = shenandoah_read_barrier(kit, base);
591 } else {
592 assert(access.is_opt_access(), "either parse or opt access");
593 assert((access.decorators() & C2_ARRAY_COPY) != 0, "can be skipped for arraycopy");
594 }
595 }
596 } else {
597 if (kit != NULL) {
598 base = shenandoah_read_barrier(kit, base);
599 } else {
600 assert(access.is_opt_access(), "either parse or opt access");
601 assert((access.decorators() & C2_ARRAY_COPY) != 0, "can be skipped for arraycopy");
602 }
603 }
604 }
605 if (base != adr->in(AddPNode::Base)) {
606 assert(kit != NULL, "no barrier should have been added");
607
608 Node* address = adr->in(AddPNode::Address);
609
610 if (address->is_AddP()) {
611 assert(address->in(AddPNode::Base) == adr->in(AddPNode::Base), "unexpected address shape");
612 assert(!address->in(AddPNode::Address)->is_AddP(), "unexpected address shape");
613 assert(address->in(AddPNode::Address) == adr->in(AddPNode::Base), "unexpected address shape");
614 address = address->clone();
615 address->set_req(AddPNode::Base, base);
616 address->set_req(AddPNode::Address, base);
617 address = kit->gvn().transform(address);
618 } else {
619 assert(address == adr->in(AddPNode::Base), "unexpected address shape");
620 address = base;
621 }
622 adr = adr->clone();
623 adr->set_req(AddPNode::Base, base);
624 adr->set_req(AddPNode::Address, address);
625 adr = kit->gvn().transform(adr);
626 access.addr().set_node(adr);
627 }
628 }
629 }
630 }
631
632 Node* ShenandoahBarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue& val) const {
633 DecoratorSet decorators = access.decorators();
634
635 const TypePtr* adr_type = access.addr().type();
636 Node* adr = access.addr().node();
637
638 bool anonymous = (decorators & ON_UNKNOWN_OOP_REF) != 0;
639 bool on_heap = (decorators & IN_HEAP) != 0;
640
641 if (!access.is_oop() || (!on_heap && !anonymous)) {
642 return BarrierSetC2::store_at_resolved(access, val);
643 }
644
645 if (access.is_parse_access()) {
646 C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access);
647 GraphKit* kit = parse_access.kit();
648
649 uint adr_idx = kit->C->get_alias_index(adr_type);
650 assert(adr_idx != Compile::AliasIdxTop, "use other store_to_memory factory" );
651 Node* value = val.node();
652 value = shenandoah_storeval_barrier(kit, value);
653 val.set_node(value);
654 shenandoah_write_barrier_pre(kit, true /* do_load */, /*kit->control(),*/ access.base(), adr, adr_idx, val.node(),
655 static_cast<const TypeOopPtr*>(val.type()), NULL /* pre_val */, access.type());
656 } else {
657 assert(access.is_opt_access(), "only for optimization passes");
658 assert(((decorators & C2_TIGHLY_COUPLED_ALLOC) != 0 || !ShenandoahSATBBarrier) && (decorators & C2_ARRAY_COPY) != 0, "unexpected caller of this code");
659 C2OptAccess& opt_access = static_cast<C2OptAccess&>(access);
660 PhaseGVN& gvn = opt_access.gvn();
661 MergeMemNode* mm = opt_access.mem();
662
663 if (ShenandoahStoreValReadBarrier) {
664 RegionNode* region = new RegionNode(3);
665 const Type* v_t = gvn.type(val.node());
666 Node* phi = new PhiNode(region, v_t->isa_oopptr() ? v_t->is_oopptr()->cast_to_nonconst() : v_t);
667 Node* cmp = gvn.transform(new CmpPNode(val.node(), gvn.zerocon(T_OBJECT)));
668 Node* bol = gvn.transform(new BoolNode(cmp, BoolTest::ne));
669 IfNode* iff = new IfNode(opt_access.ctl(), bol, PROB_LIKELY_MAG(3), COUNT_UNKNOWN);
670
671 gvn.transform(iff);
672 if (gvn.is_IterGVN()) {
673 gvn.is_IterGVN()->_worklist.push(iff);
674 } else {
675 gvn.record_for_igvn(iff);
676 }
677
678 Node* null_true = gvn.transform(new IfFalseNode(iff));
679 Node* null_false = gvn.transform(new IfTrueNode(iff));
680 region->init_req(1, null_true);
681 region->init_req(2, null_false);
682 phi->init_req(1, gvn.zerocon(T_OBJECT));
683 Node* cast = new CastPPNode(val.node(), gvn.type(val.node())->join_speculative(TypePtr::NOTNULL));
684 cast->set_req(0, null_false);
685 cast = gvn.transform(cast);
686 Node* rb = gvn.transform(new ShenandoahReadBarrierNode(null_false, gvn.C->immutable_memory(), cast, false));
687 phi->init_req(2, rb);
688 opt_access.set_ctl(gvn.transform(region));
689 val.set_node(gvn.transform(phi));
690 }
691 if (ShenandoahStoreValEnqueueBarrier) {
692 const TypePtr* adr_type = ShenandoahBarrierNode::brooks_pointer_type(gvn.type(val.node()));
693 int alias = gvn.C->get_alias_index(adr_type);
694 Node* wb = new ShenandoahWriteBarrierNode(gvn.C, opt_access.ctl(), mm->memory_at(alias), val.node());
695 Node* wb_transformed = gvn.transform(wb);
696 Node* enqueue = gvn.transform(new ShenandoahEnqueueBarrierNode(wb_transformed));
697 if (wb_transformed == wb) {
698 Node* proj = gvn.transform(new ShenandoahWBMemProjNode(wb));
699 mm->set_memory_at(alias, proj);
700 }
701 val.set_node(enqueue);
702 }
703 }
704 return BarrierSetC2::store_at_resolved(access, val);
705 }
706
707 Node* ShenandoahBarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {
708 DecoratorSet decorators = access.decorators();
709
710 Node* adr = access.addr().node();
711 Node* obj = access.base();
712
713 bool mismatched = (decorators & C2_MISMATCHED) != 0;
714 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;
715 bool on_heap = (decorators & IN_HEAP) != 0;
716 bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0;
717 bool is_unordered = (decorators & MO_UNORDERED) != 0;
718 bool need_cpu_mem_bar = !is_unordered || mismatched || !on_heap;
719
720 Node* top = Compile::current()->top();
721
722 Node* offset = adr->is_AddP() ? adr->in(AddPNode::Offset) : top;
723 Node* load = BarrierSetC2::load_at_resolved(access, val_type);
724
725 // If we are reading the value of the referent field of a Reference
726 // object (either by using Unsafe directly or through reflection)
727 // then, if SATB is enabled, we need to record the referent in an
728 // SATB log buffer using the pre-barrier mechanism.
729 // Also we need to add memory barrier to prevent commoning reads
730 // from this field across safepoint since GC can change its value.
731 bool need_read_barrier = ShenandoahKeepAliveBarrier &&
732 (on_heap && (on_weak || (unknown && offset != top && obj != top)));
733
734 if (!access.is_oop() || !need_read_barrier) {
735 return load;
736 }
737
738 assert(access.is_parse_access(), "entry not supported at optimization time");
739 C2ParseAccess& parse_access = static_cast<C2ParseAccess&>(access);
740 GraphKit* kit = parse_access.kit();
741
742 if (on_weak) {
743 // Use the pre-barrier to record the value in the referent field
744 satb_write_barrier_pre(kit, false /* do_load */,
745 NULL /* obj */, NULL /* adr */, max_juint /* alias_idx */, NULL /* val */, NULL /* val_type */,
746 load /* pre_val */, T_OBJECT);
747 // Add memory barrier to prevent commoning reads from this field
748 // across safepoint since GC can change its value.
749 kit->insert_mem_bar(Op_MemBarCPUOrder);
750 } else if (unknown) {
751 // We do not require a mem bar inside pre_barrier if need_mem_bar
752 // is set: the barriers would be emitted by us.
753 insert_pre_barrier(kit, obj, offset, load, !need_cpu_mem_bar);
754 }
755
756 return load;
757 }
758
759 Node* ShenandoahBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
760 Node* new_val, const Type* value_type) const {
761 GraphKit* kit = access.kit();
762 if (access.is_oop()) {
763 new_val = shenandoah_storeval_barrier(kit, new_val);
764 shenandoah_write_barrier_pre(kit, false /* do_load */,
765 NULL, NULL, max_juint, NULL, NULL,
766 expected_val /* pre_val */, T_OBJECT);
767
768 MemNode::MemOrd mo = access.mem_node_mo();
769 Node* mem = access.memory();
770 Node* adr = access.addr().node();
771 const TypePtr* adr_type = access.addr().type();
772 Node* load_store = NULL;
773
774 #ifdef _LP64
775 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
776 Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));
777 Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));
778 if (ShenandoahCASBarrier) {
779 load_store = kit->gvn().transform(new ShenandoahCompareAndExchangeNNode(kit->control(), mem, adr, newval_enc, oldval_enc, adr_type, value_type->make_narrowoop(), mo));
780 } else {
781 load_store = kit->gvn().transform(new CompareAndExchangeNNode(kit->control(), mem, adr, newval_enc, oldval_enc, adr_type, value_type->make_narrowoop(), mo));
782 }
783 } else
784 #endif
785 {
786 if (ShenandoahCASBarrier) {
787 load_store = kit->gvn().transform(new ShenandoahCompareAndExchangePNode(kit->control(), mem, adr, new_val, expected_val, adr_type, value_type->is_oopptr(), mo));
788 } else {
789 load_store = kit->gvn().transform(new CompareAndExchangePNode(kit->control(), mem, adr, new_val, expected_val, adr_type, value_type->is_oopptr(), mo));
790 }
791 }
792
793 access.set_raw_access(load_store);
794 pin_atomic_op(access);
795
796 #ifdef _LP64
797 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
798 return kit->gvn().transform(new DecodeNNode(load_store, load_store->get_ptr_type()));
799 }
800 #endif
801 return load_store;
802 }
803 return BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, value_type);
804 }
805
806 Node* ShenandoahBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,
807 Node* new_val, const Type* value_type) const {
808 GraphKit* kit = access.kit();
809 if (access.is_oop()) {
810 new_val = shenandoah_storeval_barrier(kit, new_val);
811 shenandoah_write_barrier_pre(kit, false /* do_load */,
812 NULL, NULL, max_juint, NULL, NULL,
813 expected_val /* pre_val */, T_OBJECT);
814 DecoratorSet decorators = access.decorators();
815 MemNode::MemOrd mo = access.mem_node_mo();
816 Node* mem = access.memory();
817 bool is_weak_cas = (decorators & C2_WEAK_CMPXCHG) != 0;
818 Node* load_store = NULL;
819 Node* adr = access.addr().node();
820 #ifdef _LP64
821 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
822 Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));
823 Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));
824 if (ShenandoahCASBarrier) {
825 if (is_weak_cas) {
826 load_store = kit->gvn().transform(new ShenandoahWeakCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
827 } else {
828 load_store = kit->gvn().transform(new ShenandoahCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
829 }
830 } else {
831 if (is_weak_cas) {
832 load_store = kit->gvn().transform(new WeakCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
833 } else {
834 load_store = kit->gvn().transform(new CompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));
835 }
836 }
837 } else
838 #endif
839 {
840 if (ShenandoahCASBarrier) {
841 if (is_weak_cas) {
842 load_store = kit->gvn().transform(new ShenandoahWeakCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
843 } else {
844 load_store = kit->gvn().transform(new ShenandoahCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
845 }
846 } else {
847 if (is_weak_cas) {
848 load_store = kit->gvn().transform(new WeakCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
849 } else {
850 load_store = kit->gvn().transform(new CompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));
851 }
852 }
853 }
854 access.set_raw_access(load_store);
855 pin_atomic_op(access);
856 return load_store;
857 }
858 return BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
859 }
860
861 Node* ShenandoahBarrierSetC2::atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* val, const Type* value_type) const {
862 GraphKit* kit = access.kit();
863 if (access.is_oop()) {
864 val = shenandoah_storeval_barrier(kit, val);
865 }
866 Node* result = BarrierSetC2::atomic_xchg_at_resolved(access, val, value_type);
867 if (access.is_oop()) {
868 shenandoah_write_barrier_pre(kit, false /* do_load */,
869 NULL, NULL, max_juint, NULL, NULL,
870 result /* pre_val */, T_OBJECT);
871 }
872 return result;
873 }
874
875 void ShenandoahBarrierSetC2::clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) const {
876 assert(!src->is_AddP(), "unexpected input");
877 src = shenandoah_read_barrier(kit, src);
878 BarrierSetC2::clone(kit, src, dst, size, is_array);
879 }
880
881 Node* ShenandoahBarrierSetC2::resolve(GraphKit* kit, Node* n, DecoratorSet decorators) const {
882 bool is_write = decorators & ACCESS_WRITE;
883 if (is_write) {
884 return shenandoah_write_barrier(kit, n);
885 } else {
886 return shenandoah_read_barrier(kit, n);
887 }
888 }
889
890 Node* ShenandoahBarrierSetC2::obj_allocate(PhaseMacroExpand* macro, Node* ctrl, Node* mem, Node* toobig_false, Node* size_in_bytes,
891 Node*& i_o, Node*& needgc_ctrl,
892 Node*& fast_oop_ctrl, Node*& fast_oop_rawmem,
893 intx prefetch_lines) const {
894 PhaseIterGVN& igvn = macro->igvn();
895
896 // Allocate several words more for the Shenandoah brooks pointer.
897 size_in_bytes = new AddXNode(size_in_bytes, igvn.MakeConX(ShenandoahBrooksPointer::byte_size()));
898 macro->transform_later(size_in_bytes);
899
900 Node* fast_oop = BarrierSetC2::obj_allocate(macro, ctrl, mem, toobig_false, size_in_bytes,
901 i_o, needgc_ctrl, fast_oop_ctrl, fast_oop_rawmem,
902 prefetch_lines);
903
904 // Bump up object for Shenandoah brooks pointer.
905 fast_oop = new AddPNode(macro->top(), fast_oop, igvn.MakeConX(ShenandoahBrooksPointer::byte_size()));
906 macro->transform_later(fast_oop);
907
908 // Initialize Shenandoah brooks pointer to point to the object itself.
909 fast_oop_rawmem = macro->make_store(fast_oop_ctrl, fast_oop_rawmem, fast_oop, ShenandoahBrooksPointer::byte_offset(), fast_oop, T_OBJECT);
910
911 return fast_oop;
912 }
913
914 // Support for GC barriers emitted during parsing
915 bool ShenandoahBarrierSetC2::is_gc_barrier_node(Node* node) const {
916 if (node->Opcode() != Op_CallLeaf && node->Opcode() != Op_CallLeafNoFP) {
917 return false;
918 }
919 CallLeafNode *call = node->as_CallLeaf();
920 if (call->_name == NULL) {
921 return false;
922 }
923
924 return strcmp(call->_name, "shenandoah_clone_barrier") == 0 ||
925 strcmp(call->_name, "shenandoah_cas_obj") == 0 ||
926 strcmp(call->_name, "shenandoah_wb_pre") == 0;
927 }
928
929 Node* ShenandoahBarrierSetC2::step_over_gc_barrier(Node* c) const {
930 return ShenandoahBarrierNode::skip_through_barrier(c);
931 }
932
933 bool ShenandoahBarrierSetC2::expand_barriers(Compile* C, PhaseIterGVN& igvn) const {
934 return !ShenandoahWriteBarrierNode::expand(C, igvn);
935 }
936
937 bool ShenandoahBarrierSetC2::optimize_loops(PhaseIdealLoop* phase, LoopOptsMode mode, VectorSet& visited, Node_Stack& nstack, Node_List& worklist) const {
938 if (mode == LoopOptsShenandoahExpand) {
939 assert(UseShenandoahGC, "only for shenandoah");
940 ShenandoahWriteBarrierNode::pin_and_expand(phase);
941 return true;
942 } else if (mode == LoopOptsShenandoahPostExpand) {
943 assert(UseShenandoahGC, "only for shenandoah");
944 visited.Clear();
945 ShenandoahWriteBarrierNode::optimize_after_expansion(visited, nstack, worklist, phase);
946 return true;
947 }
948 GrowableArray<MemoryGraphFixer*> memory_graph_fixers;
949 ShenandoahWriteBarrierNode::optimize_before_expansion(phase, memory_graph_fixers, false);
950 return false;
951 }
952
953 bool ShenandoahBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, ArrayCopyPhase phase) const {
954 bool is_oop = type == T_OBJECT || type == T_ARRAY;
955 if (!is_oop) {
956 return false;
957 }
958
959 if (tightly_coupled_alloc) {
960 if (phase == Optimization) {
961 return false;
962 }
963 return !is_clone;
964 }
965 if (phase == Optimization) {
966 return !ShenandoahStoreValEnqueueBarrier;
967 }
968 return true;
969 }
970
971 bool ShenandoahBarrierSetC2::clone_needs_postbarrier(ArrayCopyNode *ac, PhaseIterGVN& igvn) {
972 Node* src = ac->in(ArrayCopyNode::Src);
973 const TypeOopPtr* src_type = igvn.type(src)->is_oopptr();
974 if (src_type->isa_instptr() != NULL) {
975 ciInstanceKlass* ik = src_type->klass()->as_instance_klass();
976 if ((src_type->klass_is_exact() || (!ik->is_interface() && !ik->has_subklass())) && !ik->has_injected_fields()) {
977 if (ik->has_object_fields()) {
978 return true;
979 } else {
980 if (!src_type->klass_is_exact()) {
981 igvn.C->dependencies()->assert_leaf_type(ik);
982 }
983 }
984 } else {
985 return true;
986 }
987 } else if (src_type->isa_aryptr()) {
988 BasicType src_elem = src_type->klass()->as_array_klass()->element_type()->basic_type();
989 if (src_elem == T_OBJECT || src_elem == T_ARRAY) {
990 return true;
991 }
992 } else {
993 return true;
994 }
995 return false;
996 }
997
998 void ShenandoahBarrierSetC2::clone_barrier_at_expansion(ArrayCopyNode* ac, Node* call, PhaseIterGVN& igvn) const {
999 assert(ac->is_clonebasic(), "no other kind of arraycopy here");
1000
1001 if (!clone_needs_postbarrier(ac, igvn)) {
1002 BarrierSetC2::clone_barrier_at_expansion(ac, call, igvn);
1003 return;
1004 }
1005
1006 const TypePtr* raw_adr_type = TypeRawPtr::BOTTOM;
1007 Node* c = new ProjNode(call,TypeFunc::Control);
1008 c = igvn.transform(c);
1009 Node* m = new ProjNode(call, TypeFunc::Memory);
1010 m = igvn.transform(m);
1011
1012 Node* dest = ac->in(ArrayCopyNode::Dest);
1013 assert(dest->is_AddP(), "bad input");
1014 Node* barrier_call = new CallLeafNode(ShenandoahBarrierSetC2::shenandoah_clone_barrier_Type(),
1015 CAST_FROM_FN_PTR(address, ShenandoahRuntime::shenandoah_clone_barrier),
1016 "shenandoah_clone_barrier", raw_adr_type);
1017 barrier_call->init_req(TypeFunc::Control, c);
1018 barrier_call->init_req(TypeFunc::I_O , igvn.C->top());
1019 barrier_call->init_req(TypeFunc::Memory , m);
1020 barrier_call->init_req(TypeFunc::ReturnAdr, igvn.C->top());
1021 barrier_call->init_req(TypeFunc::FramePtr, igvn.C->top());
1022 barrier_call->init_req(TypeFunc::Parms+0, dest->in(AddPNode::Base));
1023
1024 barrier_call = igvn.transform(barrier_call);
1025 c = new ProjNode(barrier_call,TypeFunc::Control);
1026 c = igvn.transform(c);
1027 m = new ProjNode(barrier_call, TypeFunc::Memory);
1028 m = igvn.transform(m);
1029
1030 Node* out_c = ac->proj_out(TypeFunc::Control);
1031 Node* out_m = ac->proj_out(TypeFunc::Memory);
1032 igvn.replace_node(out_c, c);
1033 igvn.replace_node(out_m, m);
1034 }
1035
1036
1037 // Support for macro expanded GC barriers
1038 void ShenandoahBarrierSetC2::register_potential_barrier_node(Node* node) const {
1039 if (node->Opcode() == Op_ShenandoahWriteBarrier) {
1040 state()->add_shenandoah_barrier((ShenandoahWriteBarrierNode*) node);
1041 }
1042 }
1043
1044 void ShenandoahBarrierSetC2::unregister_potential_barrier_node(Node* node) const {
1045 if (node->Opcode() == Op_ShenandoahWriteBarrier) {
1046 state()->remove_shenandoah_barrier((ShenandoahWriteBarrierNode*) node);
1047 }
1048 }
1049
1050 void ShenandoahBarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* n) const {
1051 if (is_shenandoah_wb_pre_call(n)) {
1052 shenandoah_eliminate_wb_pre(n, ¯o->igvn());
1053 }
1054 }
1055
1056 void ShenandoahBarrierSetC2::shenandoah_eliminate_wb_pre(Node* call, PhaseIterGVN* igvn) const {
1057 assert(UseShenandoahGC && is_shenandoah_wb_pre_call(call), "");
1058 Node* c = call->as_Call()->proj_out(TypeFunc::Control);
1059 c = c->unique_ctrl_out();
1060 assert(c->is_Region() && c->req() == 3, "where's the pre barrier control flow?");
1061 c = c->unique_ctrl_out();
1062 assert(c->is_Region() && c->req() == 3, "where's the pre barrier control flow?");
1063 Node* iff = c->in(1)->is_IfProj() ? c->in(1)->in(0) : c->in(2)->in(0);
1064 assert(iff->is_If(), "expect test");
1065 if (!is_shenandoah_marking_if(igvn, iff)) {
1066 c = c->unique_ctrl_out();
1067 assert(c->is_Region() && c->req() == 3, "where's the pre barrier control flow?");
1068 iff = c->in(1)->is_IfProj() ? c->in(1)->in(0) : c->in(2)->in(0);
1069 assert(is_shenandoah_marking_if(igvn, iff), "expect marking test");
1070 }
1071 Node* cmpx = iff->in(1)->in(1);
1072 igvn->replace_node(cmpx, igvn->makecon(TypeInt::CC_EQ));
1073 igvn->rehash_node_delayed(call);
1074 call->del_req(call->req()-1);
1075 }
1076
1077 void ShenandoahBarrierSetC2::enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {
1078 if (node->Opcode() == Op_AddP && ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(node)) {
1079 igvn->add_users_to_worklist(node);
1080 }
1081 }
1082
1083 void ShenandoahBarrierSetC2::eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {
1084 for (uint i = 0; i < useful.size(); i++) {
1085 Node* n = useful.at(i);
1086 if (n->Opcode() == Op_AddP && ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(n)) {
1087 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1088 C->record_for_igvn(n->fast_out(i));
1089 }
1090 }
1091 }
1092 for (int i = state()->shenandoah_barriers_count()-1; i >= 0; i--) {
1093 ShenandoahWriteBarrierNode* n = state()->shenandoah_barrier(i);
1094 if (!useful.member(n)) {
1095 state()->remove_shenandoah_barrier(n);
1096 }
1097 }
1098
1099 }
1100
1101 bool ShenandoahBarrierSetC2::has_special_unique_user(const Node* node) const {
1102 assert(node->outcnt() == 1, "match only for unique out");
1103 Node* n = node->unique_out();
1104 return node->Opcode() == Op_ShenandoahWriteBarrier && n->Opcode() == Op_ShenandoahWBMemProj;
1105 }
1106
1107 void ShenandoahBarrierSetC2::add_users_to_worklist(Unique_Node_List* worklist) const {}
1108
1109 void* ShenandoahBarrierSetC2::create_barrier_state(Arena* comp_arena) const {
1110 return new(comp_arena) ShenandoahBarrierSetC2State(comp_arena);
1111 }
1112
1113 ShenandoahBarrierSetC2State* ShenandoahBarrierSetC2::state() const {
1114 return reinterpret_cast<ShenandoahBarrierSetC2State*>(Compile::current()->barrier_set_state());
1115 }
1116
1117 // If the BarrierSetC2 state has kept macro nodes in its compilation unit state to be
1118 // expanded later, then now is the time to do so.
1119 bool ShenandoahBarrierSetC2::expand_macro_nodes(PhaseMacroExpand* macro) const { return false; }
1120
1121 #ifdef ASSERT
1122 void ShenandoahBarrierSetC2::verify_gc_barriers(Compile* compile, CompilePhase phase) const {
1123 if (ShenandoahVerifyOptoBarriers && phase == BarrierSetC2::BeforeExpand) {
1124 ShenandoahBarrierNode::verify(Compile::current()->root());
1125 } else if (phase == BarrierSetC2::BeforeCodeGen) {
1126 // Verify G1 pre-barriers
1127 const int marking_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_active_offset());
1128
1129 ResourceArea *area = Thread::current()->resource_area();
1130 Unique_Node_List visited(area);
1131 Node_List worklist(area);
1132 // We're going to walk control flow backwards starting from the Root
1133 worklist.push(compile->root());
1134 while (worklist.size() > 0) {
1135 Node *x = worklist.pop();
1136 if (x == NULL || x == compile->top()) continue;
1137 if (visited.member(x)) {
1138 continue;
1139 } else {
1140 visited.push(x);
1141 }
1142
1143 if (x->is_Region()) {
1144 for (uint i = 1; i < x->req(); i++) {
1145 worklist.push(x->in(i));
1146 }
1147 } else {
1148 worklist.push(x->in(0));
1149 // We are looking for the pattern:
1150 // /->ThreadLocal
1151 // If->Bool->CmpI->LoadB->AddP->ConL(marking_offset)
1152 // \->ConI(0)
1153 // We want to verify that the If and the LoadB have the same control
1154 // See GraphKit::g1_write_barrier_pre()
1155 if (x->is_If()) {
1156 IfNode *iff = x->as_If();
1157 if (iff->in(1)->is_Bool() && iff->in(1)->in(1)->is_Cmp()) {
1158 CmpNode *cmp = iff->in(1)->in(1)->as_Cmp();
1159 if (cmp->Opcode() == Op_CmpI && cmp->in(2)->is_Con() && cmp->in(2)->bottom_type()->is_int()->get_con() == 0
1160 && cmp->in(1)->is_Load()) {
1161 LoadNode *load = cmp->in(1)->as_Load();
1162 if (load->Opcode() == Op_LoadB && load->in(2)->is_AddP() && load->in(2)->in(2)->Opcode() == Op_ThreadLocal
1163 && load->in(2)->in(3)->is_Con()
1164 && load->in(2)->in(3)->bottom_type()->is_intptr_t()->get_con() == marking_offset) {
1165
1166 Node *if_ctrl = iff->in(0);
1167 Node *load_ctrl = load->in(0);
1168
1169 if (if_ctrl != load_ctrl) {
1170 // Skip possible CProj->NeverBranch in infinite loops
1171 if ((if_ctrl->is_Proj() && if_ctrl->Opcode() == Op_CProj)
1172 && (if_ctrl->in(0)->is_MultiBranch() && if_ctrl->in(0)->Opcode() == Op_NeverBranch)) {
1173 if_ctrl = if_ctrl->in(0)->in(0);
1174 }
1175 }
1176 assert(load_ctrl != NULL && if_ctrl == load_ctrl, "controls must match");
1177 }
1178 }
1179 }
1180 }
1181 }
1182 }
1183 }
1184 }
1185 #endif
1186
1187 Node* ShenandoahBarrierSetC2::ideal_node(PhaseGVN* phase, Node* n, bool can_reshape) const {
1188 if (is_shenandoah_wb_pre_call(n)) {
1189 uint cnt = ShenandoahBarrierSetC2::write_ref_field_pre_entry_Type()->domain()->cnt();
1190 if (n->req() > cnt) {
1191 Node* addp = n->in(cnt);
1192 if (has_only_shenandoah_wb_pre_uses(addp)) {
1193 n->del_req(cnt);
1194 if (can_reshape) {
1195 phase->is_IterGVN()->_worklist.push(addp);
1196 }
1197 return n;
1198 }
1199 }
1200 }
1201 if (n->Opcode() == Op_CmpP) {
1202 Node* in1 = n->in(1);
1203 Node* in2 = n->in(2);
1204 if (in1->bottom_type() == TypePtr::NULL_PTR) {
1205 in2 = step_over_gc_barrier(in2);
1206 }
1207 if (in2->bottom_type() == TypePtr::NULL_PTR) {
1208 in1 = step_over_gc_barrier(in1);
1209 }
1210 PhaseIterGVN* igvn = phase->is_IterGVN();
1211 if (in1 != n->in(1)) {
1212 if (igvn != NULL) {
1213 n->set_req_X(1, in1, igvn);
1214 } else {
1215 n->set_req(1, in1);
1216 }
1217 assert(in2 == n->in(2), "only one change");
1218 return n;
1219 }
1220 if (in2 != n->in(2)) {
1221 if (igvn != NULL) {
1222 n->set_req_X(2, in2, igvn);
1223 } else {
1224 n->set_req(2, in2);
1225 }
1226 return n;
1227 }
1228 } else if (can_reshape &&
1229 n->Opcode() == Op_If &&
1230 ShenandoahWriteBarrierNode::is_heap_stable_test(n) &&
1231 n->in(0) != NULL) {
1232 Node* dom = n->in(0);
1233 Node* prev_dom = n;
1234 int op = n->Opcode();
1235 int dist = 16;
1236 // Search up the dominator tree for another heap stable test
1237 while (dom->Opcode() != op || // Not same opcode?
1238 !ShenandoahWriteBarrierNode::is_heap_stable_test(dom) || // Not same input 1?
1239 prev_dom->in(0) != dom) { // One path of test does not dominate?
1240 if (dist < 0) return NULL;
1241
1242 dist--;
1243 prev_dom = dom;
1244 dom = IfNode::up_one_dom(dom);
1245 if (!dom) return NULL;
1246 }
1247
1248 // Check that we did not follow a loop back to ourselves
1249 if (n == dom) {
1250 return NULL;
1251 }
1252
1253 return n->as_If()->dominated_by(prev_dom, phase->is_IterGVN());
1254 }
1255
1256 return NULL;
1257 }
1258
1259 Node* ShenandoahBarrierSetC2::identity_node(PhaseGVN* phase, Node* n) const {
1260 if (n->is_Load()) {
1261 Node *mem = n->in(MemNode::Memory);
1262 Node *value = n->as_Load()->can_see_stored_value(mem, phase);
1263 if (value) {
1264 PhaseIterGVN *igvn = phase->is_IterGVN();
1265 if (igvn != NULL &&
1266 value->is_Phi() &&
1267 value->req() > 2 &&
1268 value->in(1) != NULL &&
1269 value->in(1)->is_ShenandoahBarrier()) {
1270 if (igvn->_worklist.member(value) ||
1271 igvn->_worklist.member(value->in(0)) ||
1272 (value->in(0)->in(1) != NULL &&
1273 value->in(0)->in(1)->is_IfProj() &&
1274 (igvn->_worklist.member(value->in(0)->in(1)) ||
1275 (value->in(0)->in(1)->in(0) != NULL &&
1276 igvn->_worklist.member(value->in(0)->in(1)->in(0)))))) {
1277 igvn->_worklist.push(n);
1278 return n;
1279 }
1280 }
1281 // (This works even when value is a Con, but LoadNode::Value
1282 // usually runs first, producing the singleton type of the Con.)
1283 Node *value_no_barrier = step_over_gc_barrier(value->Opcode() == Op_EncodeP ? value->in(1) : value);
1284 if (value->Opcode() == Op_EncodeP) {
1285 if (value_no_barrier != value->in(1)) {
1286 Node *encode = value->clone();
1287 encode->set_req(1, value_no_barrier);
1288 encode = phase->transform(encode);
1289 return encode;
1290 }
1291 } else {
1292 return value_no_barrier;
1293 }
1294 }
1295 }
1296 return n;
1297 }
1298
1299 bool ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(Node* n) {
1300 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1301 Node* u = n->fast_out(i);
1302 if (!is_shenandoah_wb_pre_call(u)) {
1303 return false;
1304 }
1305 }
1306 return n->outcnt() > 0;
1307 }
1308
1309 bool ShenandoahBarrierSetC2::flatten_gc_alias_type(const TypePtr*& adr_type) const {
1310 int offset = adr_type->offset();
1311 if (offset == ShenandoahBrooksPointer::byte_offset()) {
1312 if (adr_type->isa_aryptr()) {
1313 adr_type = TypeAryPtr::make(adr_type->ptr(), adr_type->isa_aryptr()->ary(), adr_type->isa_aryptr()->klass(), false, offset);
1314 } else if (adr_type->isa_instptr()) {
1315 adr_type = TypeInstPtr::make(adr_type->ptr(), ciEnv::current()->Object_klass(), false, NULL, offset);
1316 }
1317 return true;
1318 } else {
1319 return false;
1320 }
1321 }
1322
1323 bool ShenandoahBarrierSetC2::final_graph_reshaping(Compile* compile, Node* n, uint opcode) const {
1324 switch (opcode) {
1325 case Op_CallLeaf:
1326 case Op_CallLeafNoFP: {
1327 assert (n->is_Call(), "");
1328 CallNode *call = n->as_Call();
1329 if (ShenandoahBarrierSetC2::is_shenandoah_wb_pre_call(call)) {
1330 uint cnt = ShenandoahBarrierSetC2::write_ref_field_pre_entry_Type()->domain()->cnt();
1331 if (call->req() > cnt) {
1332 assert(call->req() == cnt + 1, "only one extra input");
1333 Node *addp = call->in(cnt);
1334 assert(!ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(addp), "useless address computation?");
1335 call->del_req(cnt);
1336 }
1337 }
1338 return false;
1339 }
1340 case Op_ShenandoahCompareAndSwapP:
1341 case Op_ShenandoahCompareAndSwapN:
1342 case Op_ShenandoahWeakCompareAndSwapN:
1343 case Op_ShenandoahWeakCompareAndSwapP:
1344 case Op_ShenandoahCompareAndExchangeP:
1345 case Op_ShenandoahCompareAndExchangeN:
1346 #ifdef ASSERT
1347 if( VerifyOptoOopOffsets ) {
1348 MemNode* mem = n->as_Mem();
1349 // Check to see if address types have grounded out somehow.
1350 const TypeInstPtr *tp = mem->in(MemNode::Address)->bottom_type()->isa_instptr();
1351 ciInstanceKlass *k = tp->klass()->as_instance_klass();
1352 bool oop_offset_is_sane = k->contains_field_offset(tp->offset());
1353 assert( !tp || oop_offset_is_sane, "" );
1354 }
1355 #endif
1356 return true;
1357 case Op_ShenandoahReadBarrier:
1358 return true;
1359 case Op_ShenandoahWriteBarrier:
1360 assert(false, "should have been expanded already");
1361 return true;
1362 default:
1363 return false;
1364 }
1365 }
1366
1367 #ifdef ASSERT
1368 bool ShenandoahBarrierSetC2::verify_gc_alias_type(const TypePtr* adr_type, int offset) const {
1369 if (offset == ShenandoahBrooksPointer::byte_offset() &&
1370 (adr_type->base() == Type::AryPtr || adr_type->base() == Type::OopPtr)) {
1371 return true;
1372 } else {
1373 return false;
1374 }
1375 }
1376 #endif
1377
1378 bool ShenandoahBarrierSetC2::escape_add_to_con_graph(ConnectionGraph* conn_graph, PhaseGVN* gvn, Unique_Node_List* delayed_worklist, Node* n, uint opcode) const {
1379 switch (opcode) {
1380 case Op_ShenandoahCompareAndExchangeP:
1381 case Op_ShenandoahCompareAndExchangeN:
1382 conn_graph->add_objload_to_connection_graph(n, delayed_worklist);
1383 // fallthrough
1384 case Op_ShenandoahWeakCompareAndSwapP:
1385 case Op_ShenandoahWeakCompareAndSwapN:
1386 case Op_ShenandoahCompareAndSwapP:
1387 case Op_ShenandoahCompareAndSwapN:
1388 conn_graph->add_to_congraph_unsafe_access(n, opcode, delayed_worklist);
1389 return true;
1390 case Op_StoreP: {
1391 Node* adr = n->in(MemNode::Address);
1392 const Type* adr_type = gvn->type(adr);
1393 // Pointer stores in G1 barriers looks like unsafe access.
1394 // Ignore such stores to be able scalar replace non-escaping
1395 // allocations.
1396 if (adr_type->isa_rawptr() && adr->is_AddP()) {
1397 Node* base = conn_graph->get_addp_base(adr);
1398 if (base->Opcode() == Op_LoadP &&
1399 base->in(MemNode::Address)->is_AddP()) {
1400 adr = base->in(MemNode::Address);
1401 Node* tls = conn_graph->get_addp_base(adr);
1402 if (tls->Opcode() == Op_ThreadLocal) {
1403 int offs = (int) gvn->find_intptr_t_con(adr->in(AddPNode::Offset), Type::OffsetBot);
1404 const int buf_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
1405 if (offs == buf_offset) {
1406 return true; // Pre barrier previous oop value store.
1407 }
1408 }
1409 }
1410 }
1411 return false;
1412 }
1413 case Op_ShenandoahReadBarrier:
1414 case Op_ShenandoahWriteBarrier:
1415 // Barriers 'pass through' its arguments. I.e. what goes in, comes out.
1416 // It doesn't escape.
1417 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahBarrierNode::ValueIn), delayed_worklist);
1418 break;
1419 case Op_ShenandoahEnqueueBarrier:
1420 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), delayed_worklist);
1421 break;
1422 default:
1423 // Nothing
1424 break;
1425 }
1426 return false;
1427 }
1428
1429 bool ShenandoahBarrierSetC2::escape_add_final_edges(ConnectionGraph* conn_graph, PhaseGVN* gvn, Node* n, uint opcode) const {
1430 switch (opcode) {
1431 case Op_ShenandoahCompareAndExchangeP:
1432 case Op_ShenandoahCompareAndExchangeN: {
1433 Node *adr = n->in(MemNode::Address);
1434 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, adr, NULL);
1435 // fallthrough
1436 }
1437 case Op_ShenandoahCompareAndSwapP:
1438 case Op_ShenandoahCompareAndSwapN:
1439 case Op_ShenandoahWeakCompareAndSwapP:
1440 case Op_ShenandoahWeakCompareAndSwapN:
1441 return conn_graph->add_final_edges_unsafe_access(n, opcode);
1442 case Op_ShenandoahReadBarrier:
1443 case Op_ShenandoahWriteBarrier:
1444 // Barriers 'pass through' its arguments. I.e. what goes in, comes out.
1445 // It doesn't escape.
1446 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(ShenandoahBarrierNode::ValueIn), NULL);
1447 return true;
1448 case Op_ShenandoahEnqueueBarrier:
1449 conn_graph->add_local_var_and_edge(n, PointsToNode::NoEscape, n->in(1), NULL);
1450 return true;
1451 default:
1452 // Nothing
1453 break;
1454 }
1455 return false;
1456 }
1457
1458 bool ShenandoahBarrierSetC2::escape_has_out_with_unsafe_object(Node* n) const {
1459 return n->has_out_with(Op_ShenandoahCompareAndExchangeP) || n->has_out_with(Op_ShenandoahCompareAndExchangeN) ||
1460 n->has_out_with(Op_ShenandoahCompareAndSwapP, Op_ShenandoahCompareAndSwapN, Op_ShenandoahWeakCompareAndSwapP, Op_ShenandoahWeakCompareAndSwapN);
1461
1462 }
1463
1464 bool ShenandoahBarrierSetC2::escape_is_barrier_node(Node* n) const {
1465 return n->is_ShenandoahBarrier();
1466 }
1467
1468 bool ShenandoahBarrierSetC2::matcher_find_shared_visit(Matcher* matcher, Matcher::MStack& mstack, Node* n, uint opcode, bool& mem_op, int& mem_addr_idx) const {
1469 switch (opcode) {
1470 case Op_ShenandoahReadBarrier:
1471 if (n->in(ShenandoahBarrierNode::ValueIn)->is_DecodeNarrowPtr()) {
1472 matcher->set_shared(n->in(ShenandoahBarrierNode::ValueIn)->in(1));
1473 }
1474 matcher->set_shared(n);
1475 return true;
1476 default:
1477 break;
1478 }
1479 return false;
1480 }
1481
1482 bool ShenandoahBarrierSetC2::matcher_find_shared_post_visit(Matcher* matcher, Node* n, uint opcode) const {
1483 switch (opcode) {
1484 case Op_ShenandoahCompareAndExchangeP:
1485 case Op_ShenandoahCompareAndExchangeN:
1486 case Op_ShenandoahWeakCompareAndSwapP:
1487 case Op_ShenandoahWeakCompareAndSwapN:
1488 case Op_ShenandoahCompareAndSwapP:
1489 case Op_ShenandoahCompareAndSwapN: { // Convert trinary to binary-tree
1490 Node* newval = n->in(MemNode::ValueIn);
1491 Node* oldval = n->in(LoadStoreConditionalNode::ExpectedIn);
1492 Node* pair = new BinaryNode(oldval, newval);
1493 n->set_req(MemNode::ValueIn,pair);
1494 n->del_req(LoadStoreConditionalNode::ExpectedIn);
1495 return true;
1496 }
1497 default:
1498 break;
1499 }
1500 return false;
1501 }
1502
1503 bool ShenandoahBarrierSetC2::matcher_is_store_load_barrier(Node* x, uint xop) const {
1504 return xop == Op_ShenandoahCompareAndExchangeP ||
1505 xop == Op_ShenandoahCompareAndExchangeN ||
1506 xop == Op_ShenandoahWeakCompareAndSwapP ||
1507 xop == Op_ShenandoahWeakCompareAndSwapN ||
1508 xop == Op_ShenandoahCompareAndSwapN ||
1509 xop == Op_ShenandoahCompareAndSwapP;
1510 }
1511
1512 void ShenandoahBarrierSetC2::igvn_add_users_to_worklist(PhaseIterGVN* igvn, Node* use) const {
1513 if (use->is_ShenandoahBarrier()) {
1514 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1515 Node* u = use->fast_out(i2);
1516 Node* cmp = use->find_out_with(Op_CmpP);
1517 if (u->Opcode() == Op_CmpP) {
1518 igvn->_worklist.push(cmp);
1519 }
1520 }
1521 }
1522 }
1523
1524 void ShenandoahBarrierSetC2::ccp_analyze(PhaseCCP* ccp, Unique_Node_List& worklist, Node* use) const {
1525 if (use->is_ShenandoahBarrier()) {
1526 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1527 Node* p = use->fast_out(i2);
1528 if (p->Opcode() == Op_AddP) {
1529 for (DUIterator_Fast i3max, i3 = p->fast_outs(i3max); i3 < i3max; i3++) {
1530 Node* q = p->fast_out(i3);
1531 if (q->is_Load()) {
1532 if(q->bottom_type() != ccp->type(q)) {
1533 worklist.push(q);
1534 }
1535 }
1536 }
1537 }
1538 }
1539 }
1540 }
1541
1542 Node* ShenandoahBarrierSetC2::split_if_pre(PhaseIdealLoop* phase, Node* n) const {
1543 if (n->Opcode() == Op_ShenandoahReadBarrier) {
1544 ((ShenandoahReadBarrierNode*)n)->try_move(phase);
1545 } else if (n->Opcode() == Op_ShenandoahWriteBarrier) {
1546 return ((ShenandoahWriteBarrierNode*)n)->try_split_thru_phi(phase);
1547 }
1548
1549 return NULL;
1550 }
1551
1552 bool ShenandoahBarrierSetC2::build_loop_late_post(PhaseIdealLoop* phase, Node* n) const {
1553 return ShenandoahBarrierNode::build_loop_late_post(phase, n);
1554 }
1555
1556 bool ShenandoahBarrierSetC2::sink_node(PhaseIdealLoop* phase, Node* n, Node* x, Node* x_ctrl, Node* n_ctrl) const {
1557 if (n->is_ShenandoahBarrier()) {
1558 return x->as_ShenandoahBarrier()->sink_node(phase, x_ctrl, n_ctrl);
1559 }
1560 if (n->is_MergeMem()) {
1561 // PhaseIdealLoop::split_if_with_blocks_post() would:
1562 // _igvn._worklist.yank(x);
1563 // which sometimes causes chains of MergeMem which some of
1564 // shenandoah specific code doesn't support
1565 phase->register_new_node(x, x_ctrl);
1566 return true;
1567 }
1568 return false;
1569 }