1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "ci/ciFlatArrayKlass.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "compiler/compileLog.hpp"
30 #include "gc/shared/barrierSet.hpp"
31 #include "gc/shared/c2/barrierSetC2.hpp"
32 #include "gc/shared/tlab_globals.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "oops/flatArrayKlass.hpp"
36 #include "oops/objArrayKlass.hpp"
37 #include "opto/addnode.hpp"
38 #include "opto/arraycopynode.hpp"
39 #include "opto/cfgnode.hpp"
40 #include "opto/compile.hpp"
41 #include "opto/connode.hpp"
42 #include "opto/convertnode.hpp"
43 #include "opto/inlinetypenode.hpp"
44 #include "opto/loopnode.hpp"
45 #include "opto/machnode.hpp"
46 #include "opto/matcher.hpp"
47 #include "opto/memnode.hpp"
48 #include "opto/mempointer.hpp"
49 #include "opto/mulnode.hpp"
50 #include "opto/narrowptrnode.hpp"
51 #include "opto/phaseX.hpp"
52 #include "opto/regalloc.hpp"
53 #include "opto/regmask.hpp"
54 #include "opto/rootnode.hpp"
55 #include "opto/traceMergeStoresTag.hpp"
56 #include "opto/vectornode.hpp"
57 #include "utilities/align.hpp"
58 #include "utilities/copy.hpp"
59 #include "utilities/macros.hpp"
60 #include "utilities/powerOfTwo.hpp"
61 #include "utilities/vmError.hpp"
62
63 // Portions of code courtesy of Clifford Click
64
65 // Optimization - Graph Style
66
67 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
68
69 //=============================================================================
70 uint MemNode::size_of() const { return sizeof(*this); }
71
72 const TypePtr *MemNode::adr_type() const {
73 Node* adr = in(Address);
74 if (adr == nullptr) return nullptr; // node is dead
75 const TypePtr* cross_check = nullptr;
76 DEBUG_ONLY(cross_check = _adr_type);
77 return calculate_adr_type(adr->bottom_type(), cross_check);
78 }
79
80 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
81 if (adr != nullptr) {
82 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
83 return true;
84 }
85 }
86 return false;
87 }
88
89 #ifndef PRODUCT
90 void MemNode::dump_spec(outputStream *st) const {
91 if (in(Address) == nullptr) return; // node is dead
92 #ifndef ASSERT
93 // fake the missing field
94 const TypePtr* _adr_type = nullptr;
95 if (in(Address) != nullptr)
96 _adr_type = in(Address)->bottom_type()->isa_ptr();
97 #endif
98 dump_adr_type(this, _adr_type, st);
99
100 Compile* C = Compile::current();
101 if (C->alias_type(_adr_type)->is_volatile()) {
102 st->print(" Volatile!");
103 }
104 if (_unaligned_access) {
105 st->print(" unaligned");
106 }
107 if (_mismatched_access) {
108 st->print(" mismatched");
109 }
110 if (_unsafe_access) {
111 st->print(" unsafe");
112 }
113 }
114
115 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
116 st->print(" @");
117 if (adr_type == nullptr) {
118 st->print("null");
119 } else {
120 adr_type->dump_on(st);
121 Compile* C = Compile::current();
122 Compile::AliasType* atp = nullptr;
123 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
124 if (atp == nullptr)
125 st->print(", idx=?\?;");
126 else if (atp->index() == Compile::AliasIdxBot)
127 st->print(", idx=Bot;");
128 else if (atp->index() == Compile::AliasIdxTop)
129 st->print(", idx=Top;");
130 else if (atp->index() == Compile::AliasIdxRaw)
131 st->print(", idx=Raw;");
132 else {
133 ciField* field = atp->field();
134 if (field) {
135 st->print(", name=");
136 field->print_name_on(st);
137 }
138 st->print(", idx=%d;", atp->index());
139 }
140 }
141 }
142
143 extern void print_alias_types();
144
145 #endif
146
147 // Find the memory output corresponding to the fall-through path of a call
148 static Node* find_call_fallthrough_mem_output(CallNode* call) {
149 ResourceMark rm;
150 CallProjections* projs = call->extract_projections(false, false);
151 Node* res = projs->fallthrough_memproj;
152 assert(res != nullptr, "must have a fallthrough mem output");
153 return res;
154 }
155
156 // Try to find a better memory input for a load from a strict final field
157 static Node* try_optimize_strict_final_load_memory(PhaseGVN* phase, Node* adr, ProjNode*& base_local) {
158 intptr_t offset = 0;
159 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
160 if (base == nullptr) {
161 return nullptr;
162 }
163
164 Node* base_uncasted = base->uncast();
165 if (base_uncasted->is_Proj()) {
166 MultiNode* multi = base_uncasted->in(0)->as_Multi();
167 if (multi->is_Allocate()) {
168 base_local = base_uncasted->as_Proj();
169 return nullptr;
170 } else if (multi->is_Call()) {
171 // The oop is returned from a call, the memory can be the fallthrough output of the call
172 return find_call_fallthrough_mem_output(multi->as_Call());
173 } else if (multi->is_Start()) {
174 // The oop is a parameter
175 if (phase->C->method()->is_object_constructor() && base_uncasted->as_Proj()->_con == TypeFunc::Parms) {
176 // The receiver of a constructor is similar to the result of an AllocateNode
177 base_local = base_uncasted->as_Proj();
178 return nullptr;
179 } else {
180 // Use the start memory otherwise
181 return multi->proj_out(TypeFunc::Memory);
182 }
183 }
184 }
185
186 return nullptr;
187 }
188
189 // Whether a call can modify a strict final field, given that the object is allocated inside the
190 // current compilation unit, or is the first parameter when the compilation root is a constructor.
191 // This is equivalent to asking whether 'call' is a constructor invocation and the class declaring
192 // the target method is a subclass of the class declaring 'field'.
193 static bool call_can_modify_local_object(ciField* field, CallNode* call) {
194 if (!call->is_CallJava()) {
195 return false;
196 }
197
198 ciMethod* target = call->as_CallJava()->method();
199 if (target == nullptr || !target->is_object_constructor()) {
200 return false;
201 }
202
203 // If 'field' is declared in a class that is a subclass of the one declaring the constructor,
204 // then the field is set inside the constructor, else the field must be set before the
205 // constructor invocation. E.g. A field Super.x will be set during the execution of Sub::<init>,
206 // while a field Sub.y must be set before Super::<init> is invoked.
207 // We can try to be more heroic and decide if the receiver of the constructor invocation is the
208 // object from which we are loading from. This, however, may be problematic as deciding if 2
209 // nodes are definitely different may not be trivial, especially if the graph is not canonical.
210 // As a result, it is made more conservative for now.
211 assert(call->req() > TypeFunc::Parms, "constructor must have at least 1 argument");
212 return target->holder()->is_subclass_of(field->holder());
213 }
214
215 Node* MemNode::optimize_simple_memory_chain(Node* mchain, const TypeOopPtr* t_oop, Node* load, PhaseGVN* phase) {
216 assert(t_oop != nullptr, "sanity");
217 bool is_instance = t_oop->is_known_instance_field();
218
219 ciField* field = phase->C->alias_type(t_oop)->field();
220 bool is_strict_final_load = false;
221
222 // After macro expansion, an allocation may become a call, changing the memory input to the
223 // memory output of that call would be illegal. As a result, disallow this transformation after
224 // macro expansion.
225 if (phase->is_IterGVN() && phase->C->allow_macro_nodes() && load != nullptr && load->is_Load() && !load->as_Load()->is_mismatched_access()) {
226 if (EnableValhalla) {
227 if (field != nullptr && (field->holder()->is_inlinetype() || field->holder()->is_abstract_value_klass())) {
228 is_strict_final_load = true;
229 }
230 #ifdef ASSERT
231 if (t_oop->is_inlinetypeptr() && t_oop->inline_klass()->contains_field_offset(t_oop->offset())) {
232 assert(is_strict_final_load, "sanity check for basic cases");
233 }
234 #endif
235 } else {
236 is_strict_final_load = field != nullptr && t_oop->is_ptr_to_boxed_value();
237 }
238 }
239
240 if (!is_instance && !is_strict_final_load) {
241 return mchain;
242 }
243
244 Node* result = mchain;
245 ProjNode* base_local = nullptr;
246
247 if (is_strict_final_load) {
248 Node* adr = load->in(MemNode::Address);
249 assert(phase->type(adr) == t_oop, "inconsistent type");
250 Node* tmp = try_optimize_strict_final_load_memory(phase, adr, base_local);
251 if (tmp != nullptr) {
252 result = tmp;
253 }
254 }
255
256 uint instance_id = t_oop->instance_id();
257 Node* start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
258 Node* prev = nullptr;
259 while (prev != result) {
260 prev = result;
261 if (result == start_mem) {
262 // start_mem is the earliest memory possible
263 break;
264 }
265
266 // skip over a call which does not affect this memory slice
267 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
268 Node* proj_in = result->in(0);
269 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
270 // This is the allocation that creates the object from which we are loading from
271 break;
272 } else if (proj_in->is_Call()) {
273 // ArrayCopyNodes processed here as well
274 CallNode* call = proj_in->as_Call();
275 if (!call->may_modify(t_oop, phase)) {
276 result = call->in(TypeFunc::Memory);
277 } else if (is_strict_final_load && base_local != nullptr && !call_can_modify_local_object(field, call)) {
278 result = call->in(TypeFunc::Memory);
279 }
280 } else if (proj_in->is_Initialize()) {
281 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
282 // Stop if this is the initialization for the object instance which
283 // contains this memory slice, otherwise skip over it.
284 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
285 break;
286 }
287 if (is_instance) {
288 result = proj_in->in(TypeFunc::Memory);
289 } else if (is_strict_final_load) {
290 Node* klass = alloc->in(AllocateNode::KlassNode);
291 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
292 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
293 // Allocation of another type, must be another object
294 result = proj_in->in(TypeFunc::Memory);
295 } else if (base_local != nullptr && (base_local->is_Parm() || base_local->in(0) != alloc)) {
296 // Allocation of another object
297 result = proj_in->in(TypeFunc::Memory);
298 }
299 }
300 } else if (proj_in->is_MemBar()) {
301 ArrayCopyNode* ac = nullptr;
302 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
303 break;
304 }
305 result = proj_in->in(TypeFunc::Memory);
306 } else if (proj_in->is_top()) {
307 break; // dead code
308 } else {
309 assert(false, "unexpected projection");
310 }
311 } else if (result->is_ClearArray()) {
312 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
313 // Can not bypass initialization of the instance
314 // we are looking for.
315 break;
316 }
317 // Otherwise skip it (the call updated 'result' value).
318 } else if (result->is_MergeMem()) {
319 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
320 }
321 }
322 return result;
323 }
324
325 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
326 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
327 if (t_oop == nullptr)
328 return mchain; // don't try to optimize non-oop types
329 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
330 bool is_instance = t_oop->is_known_instance_field();
331 PhaseIterGVN *igvn = phase->is_IterGVN();
332 if (is_instance && igvn != nullptr && result->is_Phi()) {
333 PhiNode *mphi = result->as_Phi();
334 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
335 const TypePtr *t = mphi->adr_type();
336 bool do_split = false;
337 // In the following cases, Load memory input can be further optimized based on
338 // its precise address type
339 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
340 do_split = true;
341 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
342 const TypeOopPtr* mem_t =
343 t->is_oopptr()->cast_to_exactness(true)
344 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
345 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
346 if (t_oop->isa_aryptr()) {
347 mem_t = mem_t->is_aryptr()
348 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
349 ->cast_to_size(t_oop->is_aryptr()->size())
350 ->cast_to_not_flat(t_oop->is_aryptr()->is_not_flat())
351 ->cast_to_not_null_free(t_oop->is_aryptr()->is_not_null_free())
352 ->with_offset(t_oop->is_aryptr()->offset())
353 ->is_aryptr();
354 }
355 do_split = mem_t == t_oop;
356 }
357 if (do_split) {
358 // clone the Phi with our address type
359 result = mphi->split_out_instance(t_adr, igvn);
360 } else {
361 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
362 }
363 }
364 return result;
365 }
366
367 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
368 uint alias_idx = phase->C->get_alias_index(tp);
369 Node *mem = mmem;
370 #ifdef ASSERT
371 {
372 // Check that current type is consistent with the alias index used during graph construction
373 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
374 bool consistent = adr_check == nullptr || adr_check->empty() ||
375 phase->C->must_alias(adr_check, alias_idx );
376 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
377 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
378 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
379 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
380 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
381 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
382 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
383 // don't assert if it is dead code.
384 consistent = true;
385 }
386 if( !consistent ) {
387 st->print("alias_idx==%d, adr_check==", alias_idx);
388 if( adr_check == nullptr ) {
389 st->print("null");
390 } else {
391 adr_check->dump();
392 }
393 st->cr();
394 print_alias_types();
395 assert(consistent, "adr_check must match alias idx");
396 }
397 }
398 #endif
399 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
400 // means an array I have not precisely typed yet. Do not do any
401 // alias stuff with it any time soon.
402 const TypeOopPtr *toop = tp->isa_oopptr();
403 if (tp->base() != Type::AnyPtr &&
404 !(toop &&
405 toop->isa_instptr() &&
406 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
407 toop->offset() == Type::OffsetBot)) {
408 // IGVN _delay_transform may be set to true and if that is the case and mmem
409 // is already a registered node then the validation inside transform will
410 // complain.
411 Node* m = mmem;
412 PhaseIterGVN* igvn = phase->is_IterGVN();
413 if (igvn == nullptr || !igvn->delay_transform()) {
414 // compress paths and change unreachable cycles to TOP
415 // If not, we can update the input infinitely along a MergeMem cycle
416 // Equivalent code in PhiNode::Ideal
417 m = phase->transform(mmem);
418 }
419 // If transformed to a MergeMem, get the desired slice
420 // Otherwise the returned node represents memory for every slice
421 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
422 // Update input if it is progress over what we have now
423 }
424 return mem;
425 }
426
427 //--------------------------Ideal_common---------------------------------------
428 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
429 // Unhook non-raw memories from complete (macro-expanded) initializations.
430 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
431 // If our control input is a dead region, kill all below the region
432 Node *ctl = in(MemNode::Control);
433 if (ctl && remove_dead_region(phase, can_reshape))
434 return this;
435 ctl = in(MemNode::Control);
436 // Don't bother trying to transform a dead node
437 if (ctl && ctl->is_top()) return NodeSentinel;
438
439 PhaseIterGVN *igvn = phase->is_IterGVN();
440 // Wait if control on the worklist.
441 if (ctl && can_reshape && igvn != nullptr) {
442 Node* bol = nullptr;
443 Node* cmp = nullptr;
444 if (ctl->in(0)->is_If()) {
445 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
446 bol = ctl->in(0)->in(1);
447 if (bol->is_Bool())
448 cmp = ctl->in(0)->in(1)->in(1);
449 }
450 if (igvn->_worklist.member(ctl) ||
451 (bol != nullptr && igvn->_worklist.member(bol)) ||
452 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
453 // This control path may be dead.
454 // Delay this memory node transformation until the control is processed.
455 igvn->_worklist.push(this);
456 return NodeSentinel; // caller will return null
457 }
458 }
459 // Ignore if memory is dead, or self-loop
460 Node *mem = in(MemNode::Memory);
461 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
462 assert(mem != this, "dead loop in MemNode::Ideal");
463
464 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
465 // This memory slice may be dead.
466 // Delay this mem node transformation until the memory is processed.
467 igvn->_worklist.push(this);
468 return NodeSentinel; // caller will return null
469 }
470
471 Node *address = in(MemNode::Address);
472 const Type *t_adr = phase->type(address);
473 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
474
475 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
476 // Unsafe off-heap access with zero address. Remove access and other control users
477 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
478 assert(ctl != nullptr, "unsafe accesses should be control dependent");
479 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
480 Node* u = ctl->fast_out(i);
481 if (u != ctl) {
482 igvn->rehash_node_delayed(u);
483 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
484 --i, imax -= nb;
485 }
486 }
487 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
488 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
489 phase->C->root()->add_req(halt);
490 return this;
491 }
492
493 if (can_reshape && igvn != nullptr &&
494 (igvn->_worklist.member(address) ||
495 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
496 // The address's base and type may change when the address is processed.
497 // Delay this mem node transformation until the address is processed.
498 igvn->_worklist.push(this);
499 return NodeSentinel; // caller will return null
500 }
501
502 // Do NOT remove or optimize the next lines: ensure a new alias index
503 // is allocated for an oop pointer type before Escape Analysis.
504 // Note: C++ will not remove it since the call has side effect.
505 if (t_adr->isa_oopptr()) {
506 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
507 }
508
509 Node* base = nullptr;
510 if (address->is_AddP()) {
511 base = address->in(AddPNode::Base);
512 }
513 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
514 !t_adr->isa_rawptr()) {
515 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
516 // Skip this node optimization if its address has TOP base.
517 return NodeSentinel; // caller will return null
518 }
519
520 // Avoid independent memory operations
521 Node* old_mem = mem;
522
523 // The code which unhooks non-raw memories from complete (macro-expanded)
524 // initializations was removed. After macro-expansion all stores caught
525 // by Initialize node became raw stores and there is no information
526 // which memory slices they modify. So it is unsafe to move any memory
527 // operation above these stores. Also in most cases hooked non-raw memories
528 // were already unhooked by using information from detect_ptr_independence()
529 // and find_previous_store().
530
531 if (mem->is_MergeMem()) {
532 MergeMemNode* mmem = mem->as_MergeMem();
533 const TypePtr *tp = t_adr->is_ptr();
534
535 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
536 }
537
538 if (mem != old_mem) {
539 set_req_X(MemNode::Memory, mem, phase);
540 if (phase->type(mem) == Type::TOP) return NodeSentinel;
541 return this;
542 }
543
544 // let the subclass continue analyzing...
545 return nullptr;
546 }
547
548 // Helper function for proving some simple control dominations.
549 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
550 // Already assumes that 'dom' is available at 'sub', and that 'sub'
551 // is not a constant (dominated by the method's StartNode).
552 // Used by MemNode::find_previous_store to prove that the
553 // control input of a memory operation predates (dominates)
554 // an allocation it wants to look past.
555 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
556 // dominate 'sub', 'DomResult::NotDominate' if not,
557 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
558 // dead code, but at the end of IGVN, we know the definite result
559 // once the dead code is cleaned up.
560 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) {
561 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
562 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
563 }
564
565 // Check 'dom'. Skip Proj and CatchProj nodes.
566 dom = dom->find_exact_control(dom);
567 if (dom == nullptr || dom->is_top()) {
568 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
569 }
570
571 if (dom == sub) {
572 // For the case when, for example, 'sub' is Initialize and the original
573 // 'dom' is Proj node of the 'sub'.
574 return DomResult::NotDominate;
575 }
576
577 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
578 return DomResult::Dominate;
579 }
580
581 // 'dom' dominates 'sub' if its control edge and control edges
582 // of all its inputs dominate or equal to sub's control edge.
583
584 // Currently 'sub' is either Allocate, Initialize or Start nodes.
585 // Or Region for the check in LoadNode::Ideal();
586 // 'sub' should have sub->in(0) != nullptr.
587 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
588 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
589
590 // Get control edge of 'sub'.
591 Node* orig_sub = sub;
592 sub = sub->find_exact_control(sub->in(0));
593 if (sub == nullptr || sub->is_top()) {
594 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
595 }
596
597 assert(sub->is_CFG(), "expecting control");
598
599 if (sub == dom) {
600 return DomResult::Dominate;
601 }
602
603 if (sub->is_Start() || sub->is_Root()) {
604 return DomResult::NotDominate;
605 }
606
607 {
608 // Check all control edges of 'dom'.
609
610 ResourceMark rm;
611 Node_List nlist;
612 Unique_Node_List dom_list;
613
614 dom_list.push(dom);
615 bool only_dominating_controls = false;
616
617 for (uint next = 0; next < dom_list.size(); next++) {
618 Node* n = dom_list.at(next);
619 if (n == orig_sub) {
620 return DomResult::NotDominate; // One of dom's inputs dominated by sub.
621 }
622 if (!n->is_CFG() && n->pinned()) {
623 // Check only own control edge for pinned non-control nodes.
624 n = n->find_exact_control(n->in(0));
625 if (n == nullptr || n->is_top()) {
626 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
627 }
628 assert(n->is_CFG(), "expecting control");
629 dom_list.push(n);
630 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
631 only_dominating_controls = true;
632 } else if (n->is_CFG()) {
633 DomResult dom_result = n->dominates(sub, nlist);
634 if (dom_result == DomResult::Dominate) {
635 only_dominating_controls = true;
636 } else {
637 return dom_result;
638 }
639 } else {
640 // First, own control edge.
641 Node* m = n->find_exact_control(n->in(0));
642 if (m != nullptr) {
643 if (m->is_top()) {
644 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
645 }
646 dom_list.push(m);
647 }
648 // Now, the rest of edges.
649 uint cnt = n->req();
650 for (uint i = 1; i < cnt; i++) {
651 m = n->find_exact_control(n->in(i));
652 if (m == nullptr || m->is_top()) {
653 continue;
654 }
655 dom_list.push(m);
656 }
657 }
658 }
659 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
660 }
661 }
662
663 //---------------------detect_ptr_independence---------------------------------
664 // Used by MemNode::find_previous_store to prove that two base
665 // pointers are never equal.
666 // The pointers are accompanied by their associated allocations,
667 // if any, which have been previously discovered by the caller.
668 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
669 Node* p2, AllocateNode* a2,
670 PhaseTransform* phase) {
671 // Attempt to prove that these two pointers cannot be aliased.
672 // They may both manifestly be allocations, and they should differ.
673 // Or, if they are not both allocations, they can be distinct constants.
674 // Otherwise, one is an allocation and the other a pre-existing value.
675 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
676 return (p1 != p2) && p1->is_Con() && p2->is_Con();
677 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
678 return (a1 != a2);
679 } else if (a1 != nullptr) { // one allocation a1
680 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
681 return all_controls_dominate(p2, a1);
682 } else { //(a2 != null) // one allocation a2
683 return all_controls_dominate(p1, a2);
684 }
685 return false;
686 }
687
688
689 // Find an arraycopy ac that produces the memory state represented by parameter mem.
690 // Return ac if
691 // (a) can_see_stored_value=true and ac must have set the value for this load or if
692 // (b) can_see_stored_value=false and ac could have set the value for this load or if
693 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
694 // In case (c) change the parameter mem to the memory input of ac to skip it
695 // when searching stored value.
696 // Otherwise return null.
697 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
698 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
699 if (ac != nullptr) {
700 Node* ld_addp = in(MemNode::Address);
701 Node* src = ac->in(ArrayCopyNode::Src);
702 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
703
704 // This is a load from a cloned array. The corresponding arraycopy ac must
705 // have set the value for the load and we can return ac but only if the load
706 // is known to be within bounds. This is checked below.
707 if (ary_t != nullptr && ld_addp->is_AddP()) {
708 Node* ld_offs = ld_addp->in(AddPNode::Offset);
709 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
710 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
711 jlong elemsize = type2aelembytes(ary_elem);
712
713 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
714 const TypeInt* sizetype = ary_t->size();
715
716 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
717 // The load is known to be within bounds. It receives its value from ac.
718 return ac;
719 }
720 // The load is known to be out-of-bounds.
721 }
722 // The load could be out-of-bounds. It must not be hoisted but must remain
723 // dependent on the runtime range check. This is achieved by returning null.
724 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
725 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
726
727 if (ac->is_arraycopy_validated() ||
728 ac->is_copyof_validated() ||
729 ac->is_copyofrange_validated()) {
730 Node* ld_addp = in(MemNode::Address);
731 if (ld_addp->is_AddP()) {
732 Node* ld_base = ld_addp->in(AddPNode::Address);
733 Node* ld_offs = ld_addp->in(AddPNode::Offset);
734
735 Node* dest = ac->in(ArrayCopyNode::Dest);
736
737 if (dest == ld_base) {
738 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
739 assert(!ld_offs_t->empty(), "dead reference should be checked already");
740 // Take into account vector or unsafe access size
741 jlong ld_size_in_bytes = (jlong)memory_size();
742 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
743 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
744 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
745 return ac;
746 }
747 if (!can_see_stored_value) {
748 mem = ac->in(TypeFunc::Memory);
749 return ac;
750 }
751 }
752 }
753 }
754 }
755 return nullptr;
756 }
757
758 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
759 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
760 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
761 if (ld_alloc != nullptr) {
762 // Check if there is an array copy for a clone
763 Node* mb = mem->in(0);
764 ArrayCopyNode* ac = nullptr;
765 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
766 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
767 ac = mb->in(0)->in(0)->as_ArrayCopy();
768 } else {
769 // Step over GC barrier when ReduceInitialCardMarks is disabled
770 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
771 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
772
773 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
774 ac = control_proj_ac->in(0)->as_ArrayCopy();
775 }
776 }
777
778 if (ac != nullptr && ac->is_clonebasic()) {
779 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
780 if (alloc != nullptr && alloc == ld_alloc) {
781 return ac;
782 }
783 }
784 }
785 }
786 return nullptr;
787 }
788
789 // The logic for reordering loads and stores uses four steps:
790 // (a) Walk carefully past stores and initializations which we
791 // can prove are independent of this load.
792 // (b) Observe that the next memory state makes an exact match
793 // with self (load or store), and locate the relevant store.
794 // (c) Ensure that, if we were to wire self directly to the store,
795 // the optimizer would fold it up somehow.
796 // (d) Do the rewiring, and return, depending on some other part of
797 // the optimizer to fold up the load.
798 // This routine handles steps (a) and (b). Steps (c) and (d) are
799 // specific to loads and stores, so they are handled by the callers.
800 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
801 //
802 Node* MemNode::find_previous_store(PhaseValues* phase) {
803 Node* ctrl = in(MemNode::Control);
804 Node* adr = in(MemNode::Address);
805 intptr_t offset = 0;
806 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
807 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
808
809 if (offset == Type::OffsetBot)
810 return nullptr; // cannot unalias unless there are precise offsets
811
812 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
813 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
814
815 intptr_t size_in_bytes = memory_size();
816
817 Node* mem = in(MemNode::Memory); // start searching here...
818
819 int cnt = 50; // Cycle limiter
820 for (;;) { // While we can dance past unrelated stores...
821 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
822
823 Node* prev = mem;
824 if (mem->is_Store()) {
825 Node* st_adr = mem->in(MemNode::Address);
826 intptr_t st_offset = 0;
827 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
828 if (st_base == nullptr)
829 break; // inscrutable pointer
830
831 // For raw accesses it's not enough to prove that constant offsets don't intersect.
832 // We need the bases to be the equal in order for the offset check to make sense.
833 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
834 break;
835 }
836
837 if (st_offset != offset && st_offset != Type::OffsetBot) {
838 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
839 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
840 if (st_offset >= offset + size_in_bytes ||
841 st_offset <= offset - MAX_STORE ||
842 st_offset <= offset - mem->as_Store()->memory_size()) {
843 // Success: The offsets are provably independent.
844 // (You may ask, why not just test st_offset != offset and be done?
845 // The answer is that stores of different sizes can co-exist
846 // in the same sequence of RawMem effects. We sometimes initialize
847 // a whole 'tile' of array elements with a single jint or jlong.)
848 mem = mem->in(MemNode::Memory);
849 continue; // (a) advance through independent store memory
850 }
851 }
852 if (st_base != base &&
853 detect_ptr_independence(base, alloc,
854 st_base,
855 AllocateNode::Ideal_allocation(st_base),
856 phase)) {
857 // Success: The bases are provably independent.
858 mem = mem->in(MemNode::Memory);
859 continue; // (a) advance through independent store memory
860 }
861
862 // (b) At this point, if the bases or offsets do not agree, we lose,
863 // since we have not managed to prove 'this' and 'mem' independent.
864 if (st_base == base && st_offset == offset) {
865 return mem; // let caller handle steps (c), (d)
866 }
867
868 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
869 InitializeNode* st_init = mem->in(0)->as_Initialize();
870 AllocateNode* st_alloc = st_init->allocation();
871 if (st_alloc == nullptr) {
872 break; // something degenerated
873 }
874 bool known_identical = false;
875 bool known_independent = false;
876 if (alloc == st_alloc) {
877 known_identical = true;
878 } else if (alloc != nullptr) {
879 known_independent = true;
880 } else if (all_controls_dominate(this, st_alloc)) {
881 known_independent = true;
882 }
883
884 if (known_independent) {
885 // The bases are provably independent: Either they are
886 // manifestly distinct allocations, or else the control
887 // of this load dominates the store's allocation.
888 int alias_idx = phase->C->get_alias_index(adr_type());
889 if (alias_idx == Compile::AliasIdxRaw) {
890 mem = st_alloc->in(TypeFunc::Memory);
891 } else {
892 mem = st_init->memory(alias_idx);
893 }
894 continue; // (a) advance through independent store memory
895 }
896
897 // (b) at this point, if we are not looking at a store initializing
898 // the same allocation we are loading from, we lose.
899 if (known_identical) {
900 // From caller, can_see_stored_value will consult find_captured_store.
901 return mem; // let caller handle steps (c), (d)
902 }
903
904 } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
905 if (prev != mem) {
906 // Found an arraycopy but it doesn't affect that load
907 continue;
908 }
909 // Found an arraycopy that may affect that load
910 return mem;
911 } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
912 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
913 if (mem->is_Proj() && mem->in(0)->is_Call()) {
914 // ArrayCopyNodes processed here as well.
915 CallNode *call = mem->in(0)->as_Call();
916 if (!call->may_modify(addr_t, phase)) {
917 mem = call->in(TypeFunc::Memory);
918 continue; // (a) advance through independent call memory
919 }
920 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
921 ArrayCopyNode* ac = nullptr;
922 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
923 break;
924 }
925 mem = mem->in(0)->in(TypeFunc::Memory);
926 continue; // (a) advance through independent MemBar memory
927 } else if (mem->is_ClearArray()) {
928 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
929 // (the call updated 'mem' value)
930 continue; // (a) advance through independent allocation memory
931 } else {
932 // Can not bypass initialization of the instance
933 // we are looking for.
934 return mem;
935 }
936 } else if (mem->is_MergeMem()) {
937 int alias_idx = phase->C->get_alias_index(adr_type());
938 mem = mem->as_MergeMem()->memory_at(alias_idx);
939 continue; // (a) advance through independent MergeMem memory
940 }
941 }
942
943 // Unless there is an explicit 'continue', we must bail out here,
944 // because 'mem' is an inscrutable memory state (e.g., a call).
945 break;
946 }
947
948 return nullptr; // bail out
949 }
950
951 //----------------------calculate_adr_type-------------------------------------
952 // Helper function. Notices when the given type of address hits top or bottom.
953 // Also, asserts a cross-check of the type against the expected address type.
954 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
955 if (t == Type::TOP) return nullptr; // does not touch memory any more?
956 #ifdef ASSERT
957 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
958 #endif
959 const TypePtr* tp = t->isa_ptr();
960 if (tp == nullptr) {
961 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
962 return TypePtr::BOTTOM; // touches lots of memory
963 } else {
964 #ifdef ASSERT
965 // %%%% [phh] We don't check the alias index if cross_check is
966 // TypeRawPtr::BOTTOM. Needs to be investigated.
967 if (cross_check != nullptr &&
968 cross_check != TypePtr::BOTTOM &&
969 cross_check != TypeRawPtr::BOTTOM) {
970 // Recheck the alias index, to see if it has changed (due to a bug).
971 Compile* C = Compile::current();
972 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
973 "must stay in the original alias category");
974 // The type of the address must be contained in the adr_type,
975 // disregarding "null"-ness.
976 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
977 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
978 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
979 "real address must not escape from expected memory type");
980 }
981 #endif
982 return tp;
983 }
984 }
985
986 uint8_t MemNode::barrier_data(const Node* n) {
987 if (n->is_LoadStore()) {
988 return n->as_LoadStore()->barrier_data();
989 } else if (n->is_Mem()) {
990 return n->as_Mem()->barrier_data();
991 }
992 return 0;
993 }
994
995 //=============================================================================
996 // Should LoadNode::Ideal() attempt to remove control edges?
997 bool LoadNode::can_remove_control() const {
998 return !has_pinned_control_dependency();
999 }
1000 uint LoadNode::size_of() const { return sizeof(*this); }
1001 bool LoadNode::cmp(const Node &n) const {
1002 LoadNode& load = (LoadNode &)n;
1003 return Type::equals(_type, load._type) &&
1004 _control_dependency == load._control_dependency &&
1005 _mo == load._mo;
1006 }
1007 const Type *LoadNode::bottom_type() const { return _type; }
1008 uint LoadNode::ideal_reg() const {
1009 return _type->ideal_reg();
1010 }
1011
1012 #ifndef PRODUCT
1013 void LoadNode::dump_spec(outputStream *st) const {
1014 MemNode::dump_spec(st);
1015 if( !Verbose && !WizardMode ) {
1016 // standard dump does this in Verbose and WizardMode
1017 st->print(" #"); _type->dump_on(st);
1018 }
1019 if (!depends_only_on_test()) {
1020 st->print(" (does not depend only on test, ");
1021 if (control_dependency() == UnknownControl) {
1022 st->print("unknown control");
1023 } else if (control_dependency() == Pinned) {
1024 st->print("pinned");
1025 } else if (adr_type() == TypeRawPtr::BOTTOM) {
1026 st->print("raw access");
1027 } else {
1028 st->print("unknown reason");
1029 }
1030 st->print(")");
1031 }
1032 }
1033 #endif
1034
1035 #ifdef ASSERT
1036 //----------------------------is_immutable_value-------------------------------
1037 // Helper function to allow a raw load without control edge for some cases
1038 bool LoadNode::is_immutable_value(Node* adr) {
1039 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
1040 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
1041
1042 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
1043 int offsets[] = {
1044 in_bytes(JavaThread::osthread_offset()),
1045 in_bytes(JavaThread::threadObj_offset()),
1046 in_bytes(JavaThread::vthread_offset()),
1047 in_bytes(JavaThread::scopedValueCache_offset()),
1048 };
1049
1050 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
1051 if (offset == offsets[i]) {
1052 return true;
1053 }
1054 }
1055 }
1056
1057 return false;
1058 }
1059 #endif
1060
1061 //----------------------------LoadNode::make-----------------------------------
1062 // Polymorphic factory method:
1063 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
1064 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
1065 Compile* C = gvn.C;
1066
1067 // sanity check the alias category against the created node type
1068 assert(!(adr_type->isa_oopptr() &&
1069 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
1070 "use LoadKlassNode instead");
1071 assert(!(adr_type->isa_aryptr() &&
1072 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
1073 "use LoadRangeNode instead");
1074 // Check control edge of raw loads
1075 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
1076 // oop will be recorded in oop map if load crosses safepoint
1077 rt->isa_oopptr() || is_immutable_value(adr),
1078 "raw memory operations should have control edge");
1079 LoadNode* load = nullptr;
1080 switch (bt) {
1081 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1082 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1083 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1084 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1085 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1086 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
1087 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
1088 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
1089 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
1090 case T_OBJECT:
1091 case T_NARROWOOP:
1092 #ifdef _LP64
1093 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1094 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
1095 } else
1096 #endif
1097 {
1098 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
1099 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
1100 }
1101 break;
1102 default:
1103 ShouldNotReachHere();
1104 break;
1105 }
1106 assert(load != nullptr, "LoadNode should have been created");
1107 if (unaligned) {
1108 load->set_unaligned_access();
1109 }
1110 if (mismatched) {
1111 load->set_mismatched_access();
1112 }
1113 if (unsafe) {
1114 load->set_unsafe_access();
1115 }
1116 load->set_barrier_data(barrier_data);
1117 if (load->Opcode() == Op_LoadN) {
1118 Node* ld = gvn.transform(load);
1119 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1120 }
1121
1122 return load;
1123 }
1124
1125 //------------------------------hash-------------------------------------------
1126 uint LoadNode::hash() const {
1127 // unroll addition of interesting fields
1128 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1129 }
1130
1131 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1132 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1133 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1134 bool is_stable_ary = FoldStableValues &&
1135 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1136 tp->isa_aryptr()->is_stable();
1137
1138 return (eliminate_boxing && non_volatile) || is_stable_ary || tp->is_inlinetypeptr();
1139 }
1140
1141 return false;
1142 }
1143
1144 LoadNode* LoadNode::pin_array_access_node() const {
1145 const TypePtr* adr_type = this->adr_type();
1146 if (adr_type != nullptr && adr_type->isa_aryptr()) {
1147 return clone_pinned();
1148 }
1149 return nullptr;
1150 }
1151
1152 // Is the value loaded previously stored by an arraycopy? If so return
1153 // a load node that reads from the source array so we may be able to
1154 // optimize out the ArrayCopy node later.
1155 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1156 Node* ld_adr = in(MemNode::Address);
1157 intptr_t ld_off = 0;
1158 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1159 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1160 if (ac != nullptr) {
1161 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1162
1163 Node* mem = ac->in(TypeFunc::Memory);
1164 Node* ctl = ac->in(0);
1165 Node* src = ac->in(ArrayCopyNode::Src);
1166
1167 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1168 return nullptr;
1169 }
1170
1171 // load depends on the tests that validate the arraycopy
1172 LoadNode* ld = clone_pinned();
1173 Node* addp = in(MemNode::Address)->clone();
1174 if (ac->as_ArrayCopy()->is_clonebasic()) {
1175 assert(ld_alloc != nullptr, "need an alloc");
1176 assert(addp->is_AddP(), "address must be addp");
1177 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1178 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1179 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1180 addp->set_req(AddPNode::Base, src);
1181 addp->set_req(AddPNode::Address, src);
1182 } else {
1183 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1184 ac->as_ArrayCopy()->is_copyof_validated() ||
1185 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1186 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1187 addp->set_req(AddPNode::Base, src);
1188 addp->set_req(AddPNode::Address, src);
1189
1190 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1191 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1192 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1193
1194 uint shift = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem));
1195
1196 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1197 #ifdef _LP64
1198 diff = phase->transform(new ConvI2LNode(diff));
1199 #endif
1200 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1201
1202 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1203 addp->set_req(AddPNode::Offset, offset);
1204 }
1205 addp = phase->transform(addp);
1206 #ifdef ASSERT
1207 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1208 ld->_adr_type = adr_type;
1209 #endif
1210 ld->set_req(MemNode::Address, addp);
1211 ld->set_req(0, ctl);
1212 ld->set_req(MemNode::Memory, mem);
1213 return ld;
1214 }
1215 return nullptr;
1216 }
1217
1218 static Node* see_through_inline_type(PhaseValues* phase, const MemNode* load, Node* base, int offset) {
1219 if (!load->is_mismatched_access() && base != nullptr && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) {
1220 InlineTypeNode* vt = base->as_InlineType();
1221 Node* value = vt->field_value_by_offset(offset, true);
1222 assert(value != nullptr, "must see some value");
1223 return value;
1224 }
1225
1226 return nullptr;
1227 }
1228
1229 //---------------------------can_see_stored_value------------------------------
1230 // This routine exists to make sure this set of tests is done the same
1231 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1232 // will change the graph shape in a way which makes memory alive twice at the
1233 // same time (uses the Oracle model of aliasing), then some
1234 // LoadXNode::Identity will fold things back to the equivalence-class model
1235 // of aliasing.
1236 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1237 Node* ld_adr = in(MemNode::Address);
1238 intptr_t ld_off = 0;
1239 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1240 // Try to see through an InlineTypeNode
1241 // LoadN is special because the input is not compressed
1242 if (Opcode() != Op_LoadN) {
1243 Node* value = see_through_inline_type(phase, this, ld_base, ld_off);
1244 if (value != nullptr) {
1245 return value;
1246 }
1247 }
1248
1249 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1250 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1251 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1252 // This is more general than load from boxing objects.
1253 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1254 uint alias_idx = atp->index();
1255 Node* result = nullptr;
1256 Node* current = st;
1257 // Skip through chains of MemBarNodes checking the MergeMems for
1258 // new states for the slice of this load. Stop once any other
1259 // kind of node is encountered. Loads from final memory can skip
1260 // through any kind of MemBar but normal loads shouldn't skip
1261 // through MemBarAcquire since the could allow them to move out of
1262 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1263 // because alias info above them may be inaccurate (e.g., due to
1264 // mixed/mismatched unsafe accesses).
1265 bool is_final_mem = !atp->is_rewritable();
1266 while (current->is_Proj()) {
1267 int opc = current->in(0)->Opcode();
1268 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1269 opc == Op_MemBarAcquireLock ||
1270 opc == Op_LoadFence)) ||
1271 opc == Op_MemBarRelease ||
1272 opc == Op_StoreFence ||
1273 opc == Op_MemBarReleaseLock ||
1274 opc == Op_MemBarStoreStore ||
1275 opc == Op_StoreStoreFence) {
1276 Node* mem = current->in(0)->in(TypeFunc::Memory);
1277 if (mem->is_MergeMem()) {
1278 MergeMemNode* merge = mem->as_MergeMem();
1279 Node* new_st = merge->memory_at(alias_idx);
1280 if (new_st == merge->base_memory()) {
1281 // Keep searching
1282 current = new_st;
1283 continue;
1284 }
1285 // Save the new memory state for the slice and fall through
1286 // to exit.
1287 result = new_st;
1288 }
1289 }
1290 break;
1291 }
1292 if (result != nullptr) {
1293 st = result;
1294 }
1295 }
1296
1297 // Loop around twice in the case Load -> Initialize -> Store.
1298 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1299 for (int trip = 0; trip <= 1; trip++) {
1300
1301 if (st->is_Store()) {
1302 Node* st_adr = st->in(MemNode::Address);
1303 if (st_adr != ld_adr) {
1304 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1305 intptr_t st_off = 0;
1306 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1307 if (ld_base == nullptr) return nullptr;
1308 if (st_base == nullptr) return nullptr;
1309 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1310 if (ld_off != st_off) return nullptr;
1311 if (ld_off == Type::OffsetBot) return nullptr;
1312 // Same base, same offset.
1313 // Possible improvement for arrays: check index value instead of absolute offset.
1314
1315 // At this point we have proven something like this setup:
1316 // B = << base >>
1317 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1318 // S = StoreQ(AddP( B , #Off), V)
1319 // (Actually, we haven't yet proven the Q's are the same.)
1320 // In other words, we are loading from a casted version of
1321 // the same pointer-and-offset that we stored to.
1322 // Casted version may carry a dependency and it is respected.
1323 // Thus, we are able to replace L by V.
1324 }
1325 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1326 if (store_Opcode() != st->Opcode()) {
1327 return nullptr;
1328 }
1329 // LoadVector/StoreVector needs additional check to ensure the types match.
1330 if (st->is_StoreVector()) {
1331 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1332 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1333 if (in_vt != out_vt) {
1334 return nullptr;
1335 }
1336 }
1337 return st->in(MemNode::ValueIn);
1338 }
1339
1340 // A load from a freshly-created object always returns zero.
1341 // (This can happen after LoadNode::Ideal resets the load's memory input
1342 // to find_captured_store, which returned InitializeNode::zero_memory.)
1343 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1344 (st->in(0) == ld_alloc) &&
1345 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1346 // return a zero value for the load's basic type
1347 // (This is one of the few places where a generic PhaseTransform
1348 // can create new nodes. Think of it as lazily manifesting
1349 // virtually pre-existing constants.)
1350 Node* init_value = ld_alloc->in(AllocateNode::InitValue);
1351 if (init_value != nullptr) {
1352 // TODO 8350865 Scalar replacement does not work well for flat arrays.
1353 // Is this correct for non-all-zero init values? Don't we need field_value_by_offset?
1354 return init_value;
1355 }
1356 assert(ld_alloc->in(AllocateNode::RawInitValue) == nullptr, "init value may not be null");
1357 if (value_basic_type() != T_VOID) {
1358 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1359 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1360 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1361 // by the ArrayCopyNode.
1362 return phase->zerocon(value_basic_type());
1363 }
1364 } else {
1365 // TODO: materialize all-zero vector constant
1366 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1367 }
1368 }
1369
1370 // A load from an initialization barrier can match a captured store.
1371 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1372 InitializeNode* init = st->in(0)->as_Initialize();
1373 AllocateNode* alloc = init->allocation();
1374 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1375 // examine a captured store value
1376 st = init->find_captured_store(ld_off, memory_size(), phase);
1377 if (st != nullptr) {
1378 continue; // take one more trip around
1379 }
1380 }
1381 }
1382
1383 // Load boxed value from result of valueOf() call is input parameter.
1384 if (this->is_Load() && ld_adr->is_AddP() &&
1385 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1386 intptr_t ignore = 0;
1387 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1388 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1389 base = bs->step_over_gc_barrier(base);
1390 if (base != nullptr && base->is_Proj() &&
1391 base->as_Proj()->_con == TypeFunc::Parms &&
1392 base->in(0)->is_CallStaticJava() &&
1393 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1394 return base->in(0)->in(TypeFunc::Parms);
1395 }
1396 }
1397
1398 break;
1399 }
1400
1401 return nullptr;
1402 }
1403
1404 //----------------------is_instance_field_load_with_local_phi------------------
1405 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1406 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1407 in(Address)->is_AddP() ) {
1408 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1409 // Only instances and boxed values.
1410 if( t_oop != nullptr &&
1411 (t_oop->is_ptr_to_boxed_value() ||
1412 t_oop->is_known_instance_field()) &&
1413 t_oop->offset() != Type::OffsetBot &&
1414 t_oop->offset() != Type::OffsetTop) {
1415 return true;
1416 }
1417 }
1418 return false;
1419 }
1420
1421 //------------------------------Identity---------------------------------------
1422 // Loads are identity if previous store is to same address
1423 Node* LoadNode::Identity(PhaseGVN* phase) {
1424 // If the previous store-maker is the right kind of Store, and the store is
1425 // to the same address, then we are equal to the value stored.
1426 Node* mem = in(Memory);
1427 Node* value = can_see_stored_value(mem, phase);
1428 if( value ) {
1429 // byte, short & char stores truncate naturally.
1430 // A load has to load the truncated value which requires
1431 // some sort of masking operation and that requires an
1432 // Ideal call instead of an Identity call.
1433 if (memory_size() < BytesPerInt) {
1434 // If the input to the store does not fit with the load's result type,
1435 // it must be truncated via an Ideal call.
1436 if (!phase->type(value)->higher_equal(phase->type(this)))
1437 return this;
1438 }
1439 // (This works even when value is a Con, but LoadNode::Value
1440 // usually runs first, producing the singleton type of the Con.)
1441 if (!has_pinned_control_dependency() || value->is_Con()) {
1442 return value;
1443 } else {
1444 return this;
1445 }
1446 }
1447
1448 if (has_pinned_control_dependency()) {
1449 return this;
1450 }
1451 // Search for an existing data phi which was generated before for the same
1452 // instance's field to avoid infinite generation of phis in a loop.
1453 Node *region = mem->in(0);
1454 if (is_instance_field_load_with_local_phi(region)) {
1455 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1456 int this_index = phase->C->get_alias_index(addr_t);
1457 int this_offset = addr_t->offset();
1458 int this_iid = addr_t->instance_id();
1459 if (!addr_t->is_known_instance() &&
1460 addr_t->is_ptr_to_boxed_value()) {
1461 // Use _idx of address base (could be Phi node) for boxed values.
1462 intptr_t ignore = 0;
1463 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1464 if (base == nullptr) {
1465 return this;
1466 }
1467 this_iid = base->_idx;
1468 }
1469 const Type* this_type = bottom_type();
1470 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1471 Node* phi = region->fast_out(i);
1472 if (phi->is_Phi() && phi != mem &&
1473 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1474 return phi;
1475 }
1476 }
1477 }
1478
1479 return this;
1480 }
1481
1482 // Construct an equivalent unsigned load.
1483 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1484 BasicType bt = T_ILLEGAL;
1485 const Type* rt = nullptr;
1486 switch (Opcode()) {
1487 case Op_LoadUB: return this;
1488 case Op_LoadUS: return this;
1489 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1490 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1491 default:
1492 assert(false, "no unsigned variant: %s", Name());
1493 return nullptr;
1494 }
1495 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1496 raw_adr_type(), rt, bt, _mo, _control_dependency,
1497 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1498 }
1499
1500 // Construct an equivalent signed load.
1501 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1502 BasicType bt = T_ILLEGAL;
1503 const Type* rt = nullptr;
1504 switch (Opcode()) {
1505 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1506 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1507 case Op_LoadB: // fall through
1508 case Op_LoadS: // fall through
1509 case Op_LoadI: // fall through
1510 case Op_LoadL: return this;
1511 default:
1512 assert(false, "no signed variant: %s", Name());
1513 return nullptr;
1514 }
1515 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1516 raw_adr_type(), rt, bt, _mo, _control_dependency,
1517 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1518 }
1519
1520 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1521 BasicType bt = rt->basic_type();
1522 switch (Opcode()) {
1523 case Op_LoadI: return (bt == T_FLOAT);
1524 case Op_LoadL: return (bt == T_DOUBLE);
1525 case Op_LoadF: return (bt == T_INT);
1526 case Op_LoadD: return (bt == T_LONG);
1527
1528 default: return false;
1529 }
1530 }
1531
1532 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1533 BasicType bt = rt->basic_type();
1534 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1535 bool is_mismatched = is_mismatched_access();
1536 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1537 if (raw_type == nullptr) {
1538 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1539 }
1540 const int op = Opcode();
1541 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1542 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1543 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1544 raw_adr_type(), rt, bt, _mo, _control_dependency,
1545 require_atomic_access, is_unaligned_access(), is_mismatched);
1546 }
1547
1548 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1549 BasicType bt = vt->basic_type();
1550 switch (Opcode()) {
1551 case Op_StoreI: return (bt == T_FLOAT);
1552 case Op_StoreL: return (bt == T_DOUBLE);
1553 case Op_StoreF: return (bt == T_INT);
1554 case Op_StoreD: return (bt == T_LONG);
1555
1556 default: return false;
1557 }
1558 }
1559
1560 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1561 BasicType bt = vt->basic_type();
1562 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1563 const int op = Opcode();
1564 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1565 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1566 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1567 raw_adr_type(), val, bt, _mo, require_atomic_access);
1568
1569 bool is_mismatched = is_mismatched_access();
1570 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1571 if (raw_type == nullptr) {
1572 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1573 }
1574 if (is_mismatched) {
1575 st->set_mismatched_access();
1576 }
1577 return st;
1578 }
1579
1580 // We're loading from an object which has autobox behaviour.
1581 // If this object is result of a valueOf call we'll have a phi
1582 // merging a newly allocated object and a load from the cache.
1583 // We want to replace this load with the original incoming
1584 // argument to the valueOf call.
1585 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1586 assert(igvn->C->eliminate_boxing(), "sanity");
1587 intptr_t ignore = 0;
1588 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1589 if ((base == nullptr) || base->is_Phi()) {
1590 // Push the loads from the phi that comes from valueOf up
1591 // through it to allow elimination of the loads and the recovery
1592 // of the original value. It is done in split_through_phi().
1593 return nullptr;
1594 } else if (base->is_Load() ||
1595 (base->is_DecodeN() && base->in(1)->is_Load())) {
1596 // Eliminate the load of boxed value for integer types from the cache
1597 // array by deriving the value from the index into the array.
1598 // Capture the offset of the load and then reverse the computation.
1599
1600 // Get LoadN node which loads a boxing object from 'cache' array.
1601 if (base->is_DecodeN()) {
1602 base = base->in(1);
1603 }
1604 if (!base->in(Address)->is_AddP()) {
1605 return nullptr; // Complex address
1606 }
1607 AddPNode* address = base->in(Address)->as_AddP();
1608 Node* cache_base = address->in(AddPNode::Base);
1609 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1610 // Get ConP node which is static 'cache' field.
1611 cache_base = cache_base->in(1);
1612 }
1613 if ((cache_base != nullptr) && cache_base->is_Con()) {
1614 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1615 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1616 Node* elements[4];
1617 int shift = exact_log2(type2aelembytes(T_OBJECT));
1618 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1619 if (count > 0 && elements[0]->is_Con() &&
1620 (count == 1 ||
1621 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1622 elements[1]->in(2) == igvn->intcon(shift)))) {
1623 ciObjArray* array = base_type->const_oop()->as_obj_array();
1624 // Fetch the box object cache[0] at the base of the array and get its value
1625 ciInstance* box = array->obj_at(0)->as_instance();
1626 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1627 assert(ik->is_box_klass(), "sanity");
1628 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1629 if (ik->nof_nonstatic_fields() == 1) {
1630 // This should be true nonstatic_field_at requires calling
1631 // nof_nonstatic_fields so check it anyway
1632 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1633 BasicType bt = c.basic_type();
1634 // Only integer types have boxing cache.
1635 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1636 bt == T_BYTE || bt == T_SHORT ||
1637 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1638 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1639 if (cache_low != (int)cache_low) {
1640 return nullptr; // should not happen since cache is array indexed by value
1641 }
1642 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1643 if (offset != (int)offset) {
1644 return nullptr; // should not happen since cache is array indexed by value
1645 }
1646 // Add up all the offsets making of the address of the load
1647 Node* result = elements[0];
1648 for (int i = 1; i < count; i++) {
1649 result = igvn->transform(new AddXNode(result, elements[i]));
1650 }
1651 // Remove the constant offset from the address and then
1652 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1653 // remove the scaling of the offset to recover the original index.
1654 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1655 // Peel the shift off directly but wrap it in a dummy node
1656 // since Ideal can't return existing nodes
1657 igvn->_worklist.push(result); // remove dead node later
1658 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1659 } else if (result->is_Add() && result->in(2)->is_Con() &&
1660 result->in(1)->Opcode() == Op_LShiftX &&
1661 result->in(1)->in(2) == igvn->intcon(shift)) {
1662 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1663 // but for boxing cache access we know that X<<Z will not overflow
1664 // (there is range check) so we do this optimizatrion by hand here.
1665 igvn->_worklist.push(result); // remove dead node later
1666 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1667 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1668 } else {
1669 result = new RShiftXNode(result, igvn->intcon(shift));
1670 }
1671 #ifdef _LP64
1672 if (bt != T_LONG) {
1673 result = new ConvL2INode(igvn->transform(result));
1674 }
1675 #else
1676 if (bt == T_LONG) {
1677 result = new ConvI2LNode(igvn->transform(result));
1678 }
1679 #endif
1680 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1681 // Need to preserve unboxing load type if it is unsigned.
1682 switch(this->Opcode()) {
1683 case Op_LoadUB:
1684 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1685 break;
1686 case Op_LoadUS:
1687 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1688 break;
1689 }
1690 return result;
1691 }
1692 }
1693 }
1694 }
1695 }
1696 return nullptr;
1697 }
1698
1699 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1700 Node* region = phi->in(0);
1701 if (region == nullptr) {
1702 return false; // Wait stable graph
1703 }
1704 uint cnt = phi->req();
1705 for (uint i = 1; i < cnt; i++) {
1706 Node* rc = region->in(i);
1707 if (rc == nullptr || phase->type(rc) == Type::TOP)
1708 return false; // Wait stable graph
1709 Node* in = phi->in(i);
1710 if (in == nullptr || phase->type(in) == Type::TOP)
1711 return false; // Wait stable graph
1712 }
1713 return true;
1714 }
1715
1716 //------------------------------split_through_phi------------------------------
1717 // Check whether a call to 'split_through_phi' would split this load through the
1718 // Phi *base*. This method is essentially a copy of the validations performed
1719 // by 'split_through_phi'. The first use of this method was in EA code as part
1720 // of simplification of allocation merges.
1721 // Some differences from original method (split_through_phi):
1722 // - If base->is_CastPP(): base = base->in(1)
1723 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1724 Node* mem = in(Memory);
1725 Node* address = in(Address);
1726 intptr_t ignore = 0;
1727 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1728
1729 if (base->is_CastPP()) {
1730 base = base->in(1);
1731 }
1732
1733 if (req() > 3 || base == nullptr || !base->is_Phi()) {
1734 return false;
1735 }
1736
1737 if (!mem->is_Phi()) {
1738 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1739 return false;
1740 }
1741 } else if (base->in(0) != mem->in(0)) {
1742 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1743 return false;
1744 }
1745 }
1746
1747 return true;
1748 }
1749
1750 //------------------------------split_through_phi------------------------------
1751 // Split instance or boxed field load through Phi.
1752 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1753 if (req() > 3) {
1754 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1755 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1756 return nullptr;
1757 }
1758 Node* mem = in(Memory);
1759 Node* address = in(Address);
1760 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1761
1762 assert((t_oop != nullptr) &&
1763 (ignore_missing_instance_id ||
1764 t_oop->is_known_instance_field() ||
1765 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1766
1767 Compile* C = phase->C;
1768 intptr_t ignore = 0;
1769 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1770 bool base_is_phi = (base != nullptr) && base->is_Phi();
1771 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1772 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1773 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1774
1775 if (!((mem->is_Phi() || base_is_phi) &&
1776 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1777 return nullptr; // Neither memory or base are Phi
1778 }
1779
1780 if (mem->is_Phi()) {
1781 if (!stable_phi(mem->as_Phi(), phase)) {
1782 return nullptr; // Wait stable graph
1783 }
1784 uint cnt = mem->req();
1785 // Check for loop invariant memory.
1786 if (cnt == 3) {
1787 for (uint i = 1; i < cnt; i++) {
1788 Node* in = mem->in(i);
1789 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1790 if (m == mem) {
1791 if (i == 1) {
1792 // if the first edge was a loop, check second edge too.
1793 // If both are replaceable - we are in an infinite loop
1794 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1795 if (n == mem) {
1796 break;
1797 }
1798 }
1799 set_req(Memory, mem->in(cnt - i));
1800 return this; // made change
1801 }
1802 }
1803 }
1804 }
1805 if (base_is_phi) {
1806 if (!stable_phi(base->as_Phi(), phase)) {
1807 return nullptr; // Wait stable graph
1808 }
1809 uint cnt = base->req();
1810 // Check for loop invariant memory.
1811 if (cnt == 3) {
1812 for (uint i = 1; i < cnt; i++) {
1813 if (base->in(i) == base) {
1814 return nullptr; // Wait stable graph
1815 }
1816 }
1817 }
1818 }
1819
1820 // Split through Phi (see original code in loopopts.cpp).
1821 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1822
1823 // Do nothing here if Identity will find a value
1824 // (to avoid infinite chain of value phis generation).
1825 if (this != Identity(phase)) {
1826 return nullptr;
1827 }
1828
1829 // Select Region to split through.
1830 Node* region;
1831 DomResult dom_result = DomResult::Dominate;
1832 if (!base_is_phi) {
1833 assert(mem->is_Phi(), "sanity");
1834 region = mem->in(0);
1835 // Skip if the region dominates some control edge of the address.
1836 // We will check `dom_result` later.
1837 dom_result = MemNode::maybe_all_controls_dominate(address, region);
1838 } else if (!mem->is_Phi()) {
1839 assert(base_is_phi, "sanity");
1840 region = base->in(0);
1841 // Skip if the region dominates some control edge of the memory.
1842 // We will check `dom_result` later.
1843 dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1844 } else if (base->in(0) != mem->in(0)) {
1845 assert(base_is_phi && mem->is_Phi(), "sanity");
1846 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1847 if (dom_result == DomResult::Dominate) {
1848 region = base->in(0);
1849 } else {
1850 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1851 if (dom_result == DomResult::Dominate) {
1852 region = mem->in(0);
1853 }
1854 // Otherwise we encountered a complex graph.
1855 }
1856 } else {
1857 assert(base->in(0) == mem->in(0), "sanity");
1858 region = mem->in(0);
1859 }
1860
1861 PhaseIterGVN* igvn = phase->is_IterGVN();
1862 if (dom_result != DomResult::Dominate) {
1863 if (dom_result == DomResult::EncounteredDeadCode) {
1864 // There is some dead code which eventually will be removed in IGVN.
1865 // Once this is the case, we get an unambiguous dominance result.
1866 // Push the node to the worklist again until the dead code is removed.
1867 igvn->_worklist.push(this);
1868 }
1869 return nullptr;
1870 }
1871
1872 Node* phi = nullptr;
1873 const Type* this_type = this->bottom_type();
1874 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1875 int this_index = C->get_alias_index(t_oop);
1876 int this_offset = t_oop->offset();
1877 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1878 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1879 } else if (ignore_missing_instance_id) {
1880 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1881 } else {
1882 return nullptr;
1883 }
1884
1885 for (uint i = 1; i < region->req(); i++) {
1886 Node* x;
1887 Node* the_clone = nullptr;
1888 Node* in = region->in(i);
1889 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1890 in != nullptr && in->is_OuterStripMinedLoop()) {
1891 // No node should go in the outer strip mined loop
1892 in = in->in(LoopNode::EntryControl);
1893 }
1894 if (in == nullptr || in == C->top()) {
1895 x = C->top(); // Dead path? Use a dead data op
1896 } else {
1897 x = this->clone(); // Else clone up the data op
1898 the_clone = x; // Remember for possible deletion.
1899 // Alter data node to use pre-phi inputs
1900 if (this->in(0) == region) {
1901 x->set_req(0, in);
1902 } else {
1903 x->set_req(0, nullptr);
1904 }
1905 if (mem->is_Phi() && (mem->in(0) == region)) {
1906 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1907 }
1908 if (address->is_Phi() && address->in(0) == region) {
1909 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1910 }
1911 if (base_is_phi && (base->in(0) == region)) {
1912 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1913 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1914 x->set_req(Address, adr_x);
1915 }
1916 }
1917 // Check for a 'win' on some paths
1918 const Type *t = x->Value(igvn);
1919
1920 bool singleton = t->singleton();
1921
1922 // See comments in PhaseIdealLoop::split_thru_phi().
1923 if (singleton && t == Type::TOP) {
1924 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1925 }
1926
1927 if (singleton) {
1928 x = igvn->makecon(t);
1929 } else {
1930 // We now call Identity to try to simplify the cloned node.
1931 // Note that some Identity methods call phase->type(this).
1932 // Make sure that the type array is big enough for
1933 // our new node, even though we may throw the node away.
1934 // (This tweaking with igvn only works because x is a new node.)
1935 igvn->set_type(x, t);
1936 // If x is a TypeNode, capture any more-precise type permanently into Node
1937 // otherwise it will be not updated during igvn->transform since
1938 // igvn->type(x) is set to x->Value() already.
1939 x->raise_bottom_type(t);
1940 Node* y = x->Identity(igvn);
1941 if (y != x) {
1942 x = y;
1943 } else {
1944 y = igvn->hash_find_insert(x);
1945 if (y) {
1946 x = y;
1947 } else {
1948 // Else x is a new node we are keeping
1949 // We do not need register_new_node_with_optimizer
1950 // because set_type has already been called.
1951 igvn->_worklist.push(x);
1952 }
1953 }
1954 }
1955 if (x != the_clone && the_clone != nullptr) {
1956 igvn->remove_dead_node(the_clone);
1957 }
1958 phi->set_req(i, x);
1959 }
1960 // Record Phi
1961 igvn->register_new_node_with_optimizer(phi);
1962 return phi;
1963 }
1964
1965 AllocateNode* LoadNode::is_new_object_mark_load() const {
1966 if (Opcode() == Op_LoadX) {
1967 Node* address = in(MemNode::Address);
1968 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1969 Node* mem = in(MemNode::Memory);
1970 if (alloc != nullptr && mem->is_Proj() &&
1971 mem->in(0) != nullptr &&
1972 mem->in(0) == alloc->initialization() &&
1973 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1974 return alloc;
1975 }
1976 }
1977 return nullptr;
1978 }
1979
1980
1981 //------------------------------Ideal------------------------------------------
1982 // If the load is from Field memory and the pointer is non-null, it might be possible to
1983 // zero out the control input.
1984 // If the offset is constant and the base is an object allocation,
1985 // try to hook me up to the exact initializing store.
1986 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1987 if (has_pinned_control_dependency()) {
1988 return nullptr;
1989 }
1990 Node* p = MemNode::Ideal_common(phase, can_reshape);
1991 if (p) return (p == NodeSentinel) ? nullptr : p;
1992
1993 Node* ctrl = in(MemNode::Control);
1994 Node* address = in(MemNode::Address);
1995 bool progress = false;
1996
1997 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1998 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1999
2000 // Skip up past a SafePoint control. Cannot do this for Stores because
2001 // pointer stores & cardmarks must stay on the same side of a SafePoint.
2002 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
2003 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
2004 !addr_mark &&
2005 (depends_only_on_test() || has_unknown_control_dependency())) {
2006 ctrl = ctrl->in(0);
2007 set_req(MemNode::Control,ctrl);
2008 progress = true;
2009 }
2010
2011 intptr_t ignore = 0;
2012 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
2013 if (base != nullptr
2014 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
2015 // Check for useless control edge in some common special cases
2016 if (in(MemNode::Control) != nullptr
2017 && !(phase->type(address)->is_inlinetypeptr() && is_mismatched_access())
2018 && can_remove_control()
2019 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
2020 && all_controls_dominate(base, phase->C->start())) {
2021 // A method-invariant, non-null address (constant or 'this' argument).
2022 set_req(MemNode::Control, nullptr);
2023 progress = true;
2024 }
2025 }
2026
2027 Node* mem = in(MemNode::Memory);
2028 const TypePtr *addr_t = phase->type(address)->isa_ptr();
2029
2030 if (can_reshape && (addr_t != nullptr)) {
2031 // try to optimize our memory input
2032 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
2033 if (opt_mem != mem) {
2034 set_req_X(MemNode::Memory, opt_mem, phase);
2035 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
2036 return this;
2037 }
2038 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
2039 if ((t_oop != nullptr) &&
2040 (t_oop->is_known_instance_field() ||
2041 t_oop->is_ptr_to_boxed_value())) {
2042 PhaseIterGVN *igvn = phase->is_IterGVN();
2043 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
2044 if (igvn->_worklist.member(opt_mem)) {
2045 // Delay this transformation until memory Phi is processed.
2046 igvn->_worklist.push(this);
2047 return nullptr;
2048 }
2049 // Split instance field load through Phi.
2050 Node* result = split_through_phi(phase);
2051 if (result != nullptr) return result;
2052
2053 if (t_oop->is_ptr_to_boxed_value()) {
2054 Node* result = eliminate_autobox(igvn);
2055 if (result != nullptr) return result;
2056 }
2057 }
2058 }
2059
2060 // Is there a dominating load that loads the same value? Leave
2061 // anything that is not a load of a field/array element (like
2062 // barriers etc.) alone
2063 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
2064 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
2065 Node *use = mem->fast_out(i);
2066 if (use != this &&
2067 use->Opcode() == Opcode() &&
2068 use->in(0) != nullptr &&
2069 use->in(0) != in(0) &&
2070 use->in(Address) == in(Address)) {
2071 Node* ctl = in(0);
2072 for (int i = 0; i < 10 && ctl != nullptr; i++) {
2073 ctl = IfNode::up_one_dom(ctl);
2074 if (ctl == use->in(0)) {
2075 set_req(0, use->in(0));
2076 return this;
2077 }
2078 }
2079 }
2080 }
2081 }
2082
2083 // Check for prior store with a different base or offset; make Load
2084 // independent. Skip through any number of them. Bail out if the stores
2085 // are in an endless dead cycle and report no progress. This is a key
2086 // transform for Reflection. However, if after skipping through the Stores
2087 // we can't then fold up against a prior store do NOT do the transform as
2088 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
2089 // array memory alive twice: once for the hoisted Load and again after the
2090 // bypassed Store. This situation only works if EVERYBODY who does
2091 // anti-dependence work knows how to bypass. I.e. we need all
2092 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
2093 // the alias index stuff. So instead, peek through Stores and IFF we can
2094 // fold up, do so.
2095 Node* prev_mem = find_previous_store(phase);
2096 if (prev_mem != nullptr) {
2097 Node* value = can_see_arraycopy_value(prev_mem, phase);
2098 if (value != nullptr) {
2099 return value;
2100 }
2101 }
2102 // Steps (a), (b): Walk past independent stores to find an exact match.
2103 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
2104 // (c) See if we can fold up on the spot, but don't fold up here.
2105 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
2106 // just return a prior value, which is done by Identity calls.
2107 if (can_see_stored_value(prev_mem, phase)) {
2108 // Make ready for step (d):
2109 set_req_X(MemNode::Memory, prev_mem, phase);
2110 return this;
2111 }
2112 }
2113
2114 if (progress) {
2115 return this;
2116 }
2117
2118 if (!can_reshape) {
2119 phase->record_for_igvn(this);
2120 }
2121 return nullptr;
2122 }
2123
2124 // Helper to recognize certain Klass fields which are invariant across
2125 // some group of array types (e.g., int[] or all T[] where T < Object).
2126 const Type*
2127 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
2128 ciKlass* klass) const {
2129 assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
2130 "must not happen");
2131 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
2132 // The field is Klass::_access_flags. Return its (constant) value.
2133 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
2134 return TypeInt::make(klass->access_flags());
2135 }
2136 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
2137 // The field is Klass::_misc_flags. Return its (constant) value.
2138 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
2139 return TypeInt::make(klass->misc_flags());
2140 }
2141 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
2142 // The field is Klass::_layout_helper. Return its constant value if known.
2143 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2144 return TypeInt::make(klass->layout_helper());
2145 }
2146
2147 // No match.
2148 return nullptr;
2149 }
2150
2151 //------------------------------Value-----------------------------------------
2152 const Type* LoadNode::Value(PhaseGVN* phase) const {
2153 // Either input is TOP ==> the result is TOP
2154 Node* mem = in(MemNode::Memory);
2155 const Type *t1 = phase->type(mem);
2156 if (t1 == Type::TOP) return Type::TOP;
2157 Node* adr = in(MemNode::Address);
2158 const TypePtr* tp = phase->type(adr)->isa_ptr();
2159 if (tp == nullptr || tp->empty()) return Type::TOP;
2160 int off = tp->offset();
2161 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2162 Compile* C = phase->C;
2163
2164 // If we are loading from a freshly-allocated object, produce a zero,
2165 // if the load is provably beyond the header of the object.
2166 // (Also allow a variable load from a fresh array to produce zero.)
2167 const TypeOopPtr* tinst = tp->isa_oopptr();
2168 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2169 Node* value = can_see_stored_value(mem, phase);
2170 if (value != nullptr && value->is_Con()) {
2171 assert(value->bottom_type()->higher_equal(_type), "sanity");
2172 return value->bottom_type();
2173 }
2174
2175 // Try to guess loaded type from pointer type
2176 if (tp->isa_aryptr()) {
2177 const TypeAryPtr* ary = tp->is_aryptr();
2178 const Type* t = ary->elem();
2179
2180 // Determine whether the reference is beyond the header or not, by comparing
2181 // the offset against the offset of the start of the array's data.
2182 // Different array types begin at slightly different offsets (12 vs. 16).
2183 // We choose T_BYTE as an example base type that is least restrictive
2184 // as to alignment, which will therefore produce the smallest
2185 // possible base offset.
2186 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2187 const bool off_beyond_header = (off >= min_base_off);
2188
2189 // Try to constant-fold a stable array element.
2190 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2191 // Make sure the reference is not into the header and the offset is constant
2192 ciObject* aobj = ary->const_oop();
2193 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2194 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2195 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2196 stable_dimension,
2197 value_basic_type(), is_unsigned());
2198 if (con_type != nullptr) {
2199 return con_type;
2200 }
2201 }
2202 }
2203
2204 // Don't do this for integer types. There is only potential profit if
2205 // the element type t is lower than _type; that is, for int types, if _type is
2206 // more restrictive than t. This only happens here if one is short and the other
2207 // char (both 16 bits), and in those cases we've made an intentional decision
2208 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2209 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2210 //
2211 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2212 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2213 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2214 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2215 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2216 // In fact, that could have been the original type of p1, and p1 could have
2217 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2218 // expression (LShiftL quux 3) independently optimized to the constant 8.
2219 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2220 && (_type->isa_vect() == nullptr)
2221 && !ary->is_flat()
2222 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2223 // t might actually be lower than _type, if _type is a unique
2224 // concrete subclass of abstract class t.
2225 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2226 const Type* jt = t->join_speculative(_type);
2227 // In any case, do not allow the join, per se, to empty out the type.
2228 if (jt->empty() && !t->empty()) {
2229 // This can happen if a interface-typed array narrows to a class type.
2230 jt = _type;
2231 }
2232 #ifdef ASSERT
2233 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2234 // The pointers in the autobox arrays are always non-null
2235 Node* base = adr->in(AddPNode::Base);
2236 if ((base != nullptr) && base->is_DecodeN()) {
2237 // Get LoadN node which loads IntegerCache.cache field
2238 base = base->in(1);
2239 }
2240 if ((base != nullptr) && base->is_Con()) {
2241 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2242 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2243 // It could be narrow oop
2244 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2245 }
2246 }
2247 }
2248 #endif
2249 return jt;
2250 }
2251 }
2252 } else if (tp->base() == Type::InstPtr) {
2253 assert( off != Type::OffsetBot ||
2254 // arrays can be cast to Objects
2255 !tp->isa_instptr() ||
2256 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2257 // Default value load
2258 tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() ||
2259 // unsafe field access may not have a constant offset
2260 C->has_unsafe_access(),
2261 "Field accesses must be precise" );
2262 // For oop loads, we expect the _type to be precise.
2263
2264 const TypeInstPtr* tinst = tp->is_instptr();
2265 BasicType bt = value_basic_type();
2266
2267 // Optimize loads from constant fields.
2268 ciObject* const_oop = tinst->const_oop();
2269 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2270 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2271 if (con_type != nullptr) {
2272 return con_type;
2273 }
2274 }
2275 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2276 assert(off != Type::OffsetBot ||
2277 !tp->isa_instklassptr() ||
2278 // arrays can be cast to Objects
2279 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2280 // also allow array-loading from the primary supertype
2281 // array during subtype checks
2282 Opcode() == Op_LoadKlass,
2283 "Field accesses must be precise");
2284 // For klass/static loads, we expect the _type to be precise
2285 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2286 /* With mirrors being an indirect in the Klass*
2287 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2288 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2289 *
2290 * So check the type and klass of the node before the LoadP.
2291 */
2292 Node* adr2 = adr->in(MemNode::Address);
2293 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2294 if (tkls != nullptr && !StressReflectiveCode) {
2295 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2296 ciKlass* klass = tkls->exact_klass();
2297 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2298 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2299 return TypeInstPtr::make(klass->java_mirror());
2300 }
2301 }
2302 }
2303
2304 const TypeKlassPtr *tkls = tp->isa_klassptr();
2305 if (tkls != nullptr) {
2306 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2307 ciKlass* klass = tkls->exact_klass();
2308 // We are loading a field from a Klass metaobject whose identity
2309 // is known at compile time (the type is "exact" or "precise").
2310 // Check for fields we know are maintained as constants by the VM.
2311 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2312 // The field is Klass::_super_check_offset. Return its (constant) value.
2313 // (Folds up type checking code.)
2314 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2315 return TypeInt::make(klass->super_check_offset());
2316 }
2317 if (klass->is_flat_array_klass() && tkls->offset() == in_bytes(FlatArrayKlass::layout_kind_offset())) {
2318 assert(Opcode() == Op_LoadI, "must load an int from _layout_kind");
2319 return TypeInt::make(static_cast<jint>(klass->as_flat_array_klass()->layout_kind()));
2320 }
2321 if (UseCompactObjectHeaders) { // TODO: Should EnableValhalla also take this path ?
2322 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2323 // The field is Klass::_prototype_header. Return its (constant) value.
2324 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2325 return TypeX::make(klass->prototype_header());
2326 }
2327 }
2328 // Compute index into primary_supers array
2329 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2330 // Check for overflowing; use unsigned compare to handle the negative case.
2331 if( depth < ciKlass::primary_super_limit() ) {
2332 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2333 // (Folds up type checking code.)
2334 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2335 ciKlass *ss = klass->super_of_depth(depth);
2336 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2337 }
2338 const Type* aift = load_array_final_field(tkls, klass);
2339 if (aift != nullptr) return aift;
2340 }
2341
2342 // We can still check if we are loading from the primary_supers array at a
2343 // shallow enough depth. Even though the klass is not exact, entries less
2344 // than or equal to its super depth are correct.
2345 if (tkls->is_loaded()) {
2346 ciKlass* klass = nullptr;
2347 if (tkls->isa_instklassptr()) {
2348 klass = tkls->is_instklassptr()->instance_klass();
2349 } else {
2350 int dims;
2351 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2352 if (inner->isa_instklassptr()) {
2353 klass = inner->is_instklassptr()->instance_klass();
2354 klass = ciObjArrayKlass::make(klass, dims);
2355 }
2356 }
2357 if (klass != nullptr) {
2358 // Compute index into primary_supers array
2359 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2360 // Check for overflowing; use unsigned compare to handle the negative case.
2361 if (depth < ciKlass::primary_super_limit() &&
2362 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2363 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2364 // (Folds up type checking code.)
2365 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2366 ciKlass *ss = klass->super_of_depth(depth);
2367 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2368 }
2369 }
2370 }
2371
2372 // If the type is enough to determine that the thing is not an array,
2373 // we can give the layout_helper a positive interval type.
2374 // This will help short-circuit some reflective code.
2375 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2376 tkls->isa_instklassptr() && // not directly typed as an array
2377 !tkls->is_instklassptr()->might_be_an_array() // not the supertype of all T[] (java.lang.Object) or has an interface that is not Serializable or Cloneable
2378 ) {
2379 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2380 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2381 // The key property of this type is that it folds up tests
2382 // for array-ness, since it proves that the layout_helper is positive.
2383 // Thus, a generic value like the basic object layout helper works fine.
2384 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2385 }
2386 }
2387
2388 bool is_vect = (_type->isa_vect() != nullptr);
2389 if (is_instance && !is_vect) {
2390 // If we have an instance type and our memory input is the
2391 // programs's initial memory state, there is no matching store,
2392 // so just return a zero of the appropriate type -
2393 // except if it is vectorized - then we have no zero constant.
2394 Node *mem = in(MemNode::Memory);
2395 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2396 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2397 // TODO 8350865 Scalar replacement does not work well for flat arrays.
2398 // Escape Analysis assumes that arrays are always zeroed during allocation which is not true for null-free arrays
2399 // ConnectionGraph::split_unique_types will re-wire the memory of loads from such arrays around the allocation
2400 // TestArrays::test6 and test152 and TestBasicFunctionality::test20 are affected by this.
2401 if (tp->isa_aryptr() && tp->is_aryptr()->is_flat() && tp->is_aryptr()->is_null_free()) {
2402 intptr_t offset = 0;
2403 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2404 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
2405 if (alloc != nullptr && alloc->is_AllocateArray() && alloc->in(AllocateNode::InitValue) != nullptr) {
2406 return _type;
2407 }
2408 }
2409 return Type::get_zero_type(_type->basic_type());
2410 }
2411 }
2412 if (!UseCompactObjectHeaders) {
2413 Node* alloc = is_new_object_mark_load();
2414 if (alloc != nullptr) {
2415 if (EnableValhalla) {
2416 // The mark word may contain property bits (inline, flat, null-free)
2417 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2418 const TypeKlassPtr* tkls = phase->type(klass_node)->isa_klassptr();
2419 if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact()) {
2420 return TypeX::make(tkls->exact_klass()->prototype_header());
2421 }
2422 } else {
2423 return TypeX::make(markWord::prototype().value());
2424 }
2425 }
2426 }
2427
2428 return _type;
2429 }
2430
2431 //------------------------------match_edge-------------------------------------
2432 // Do we Match on this edge index or not? Match only the address.
2433 uint LoadNode::match_edge(uint idx) const {
2434 return idx == MemNode::Address;
2435 }
2436
2437 //--------------------------LoadBNode::Ideal--------------------------------------
2438 //
2439 // If the previous store is to the same address as this load,
2440 // and the value stored was larger than a byte, replace this load
2441 // with the value stored truncated to a byte. If no truncation is
2442 // needed, the replacement is done in LoadNode::Identity().
2443 //
2444 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2445 Node* mem = in(MemNode::Memory);
2446 Node* value = can_see_stored_value(mem,phase);
2447 if (value != nullptr) {
2448 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2449 if (narrow != value) {
2450 return narrow;
2451 }
2452 }
2453 // Identity call will handle the case where truncation is not needed.
2454 return LoadNode::Ideal(phase, can_reshape);
2455 }
2456
2457 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2458 Node* mem = in(MemNode::Memory);
2459 Node* value = can_see_stored_value(mem,phase);
2460 if (value != nullptr && value->is_Con() &&
2461 !value->bottom_type()->higher_equal(_type)) {
2462 // If the input to the store does not fit with the load's result type,
2463 // it must be truncated. We can't delay until Ideal call since
2464 // a singleton Value is needed for split_thru_phi optimization.
2465 int con = value->get_int();
2466 return TypeInt::make((con << 24) >> 24);
2467 }
2468 return LoadNode::Value(phase);
2469 }
2470
2471 //--------------------------LoadUBNode::Ideal-------------------------------------
2472 //
2473 // If the previous store is to the same address as this load,
2474 // and the value stored was larger than a byte, replace this load
2475 // with the value stored truncated to a byte. If no truncation is
2476 // needed, the replacement is done in LoadNode::Identity().
2477 //
2478 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2479 Node* mem = in(MemNode::Memory);
2480 Node* value = can_see_stored_value(mem, phase);
2481 if (value != nullptr) {
2482 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2483 if (narrow != value) {
2484 return narrow;
2485 }
2486 }
2487 // Identity call will handle the case where truncation is not needed.
2488 return LoadNode::Ideal(phase, can_reshape);
2489 }
2490
2491 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2492 Node* mem = in(MemNode::Memory);
2493 Node* value = can_see_stored_value(mem,phase);
2494 if (value != nullptr && value->is_Con() &&
2495 !value->bottom_type()->higher_equal(_type)) {
2496 // If the input to the store does not fit with the load's result type,
2497 // it must be truncated. We can't delay until Ideal call since
2498 // a singleton Value is needed for split_thru_phi optimization.
2499 int con = value->get_int();
2500 return TypeInt::make(con & 0xFF);
2501 }
2502 return LoadNode::Value(phase);
2503 }
2504
2505 //--------------------------LoadUSNode::Ideal-------------------------------------
2506 //
2507 // If the previous store is to the same address as this load,
2508 // and the value stored was larger than a char, replace this load
2509 // with the value stored truncated to a char. If no truncation is
2510 // needed, the replacement is done in LoadNode::Identity().
2511 //
2512 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2513 Node* mem = in(MemNode::Memory);
2514 Node* value = can_see_stored_value(mem,phase);
2515 if (value != nullptr) {
2516 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2517 if (narrow != value) {
2518 return narrow;
2519 }
2520 }
2521 // Identity call will handle the case where truncation is not needed.
2522 return LoadNode::Ideal(phase, can_reshape);
2523 }
2524
2525 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2526 Node* mem = in(MemNode::Memory);
2527 Node* value = can_see_stored_value(mem,phase);
2528 if (value != nullptr && value->is_Con() &&
2529 !value->bottom_type()->higher_equal(_type)) {
2530 // If the input to the store does not fit with the load's result type,
2531 // it must be truncated. We can't delay until Ideal call since
2532 // a singleton Value is needed for split_thru_phi optimization.
2533 int con = value->get_int();
2534 return TypeInt::make(con & 0xFFFF);
2535 }
2536 return LoadNode::Value(phase);
2537 }
2538
2539 //--------------------------LoadSNode::Ideal--------------------------------------
2540 //
2541 // If the previous store is to the same address as this load,
2542 // and the value stored was larger than a short, replace this load
2543 // with the value stored truncated to a short. If no truncation is
2544 // needed, the replacement is done in LoadNode::Identity().
2545 //
2546 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2547 Node* mem = in(MemNode::Memory);
2548 Node* value = can_see_stored_value(mem,phase);
2549 if (value != nullptr) {
2550 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2551 if (narrow != value) {
2552 return narrow;
2553 }
2554 }
2555 // Identity call will handle the case where truncation is not needed.
2556 return LoadNode::Ideal(phase, can_reshape);
2557 }
2558
2559 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2560 Node* mem = in(MemNode::Memory);
2561 Node* value = can_see_stored_value(mem,phase);
2562 if (value != nullptr && value->is_Con() &&
2563 !value->bottom_type()->higher_equal(_type)) {
2564 // If the input to the store does not fit with the load's result type,
2565 // it must be truncated. We can't delay until Ideal call since
2566 // a singleton Value is needed for split_thru_phi optimization.
2567 int con = value->get_int();
2568 return TypeInt::make((con << 16) >> 16);
2569 }
2570 return LoadNode::Value(phase);
2571 }
2572
2573 Node* LoadNNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2574 // Loading from an InlineType, find the input and make an EncodeP
2575 Node* addr = in(Address);
2576 intptr_t offset;
2577 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
2578 Node* value = see_through_inline_type(phase, this, base, offset);
2579 if (value != nullptr) {
2580 return new EncodePNode(value, type());
2581 }
2582
2583 return LoadNode::Ideal(phase, can_reshape);
2584 }
2585
2586 //=============================================================================
2587 //----------------------------LoadKlassNode::make------------------------------
2588 // Polymorphic factory method:
2589 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2590 // sanity check the alias category against the created node type
2591 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2592 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2593 #ifdef _LP64
2594 if (adr_type->is_ptr_to_narrowklass()) {
2595 assert(UseCompressedClassPointers, "no compressed klasses");
2596 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2597 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2598 }
2599 #endif
2600 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2601 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2602 }
2603
2604 //------------------------------Value------------------------------------------
2605 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2606 return klass_value_common(phase);
2607 }
2608
2609 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2610 // Either input is TOP ==> the result is TOP
2611 const Type *t1 = phase->type( in(MemNode::Memory) );
2612 if (t1 == Type::TOP) return Type::TOP;
2613 Node *adr = in(MemNode::Address);
2614 const Type *t2 = phase->type( adr );
2615 if (t2 == Type::TOP) return Type::TOP;
2616 const TypePtr *tp = t2->is_ptr();
2617 if (TypePtr::above_centerline(tp->ptr()) ||
2618 tp->ptr() == TypePtr::Null) return Type::TOP;
2619
2620 // Return a more precise klass, if possible
2621 const TypeInstPtr *tinst = tp->isa_instptr();
2622 if (tinst != nullptr) {
2623 ciInstanceKlass* ik = tinst->instance_klass();
2624 int offset = tinst->offset();
2625 if (ik == phase->C->env()->Class_klass()
2626 && (offset == java_lang_Class::klass_offset() ||
2627 offset == java_lang_Class::array_klass_offset())) {
2628 // We are loading a special hidden field from a Class mirror object,
2629 // the field which points to the VM's Klass metaobject.
2630 ciType* t = tinst->java_mirror_type();
2631 // java_mirror_type returns non-null for compile-time Class constants.
2632 if (t != nullptr) {
2633 // constant oop => constant klass
2634 if (offset == java_lang_Class::array_klass_offset()) {
2635 if (t->is_void()) {
2636 // We cannot create a void array. Since void is a primitive type return null
2637 // klass. Users of this result need to do a null check on the returned klass.
2638 return TypePtr::NULL_PTR;
2639 }
2640 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2641 }
2642 if (!t->is_klass()) {
2643 // a primitive Class (e.g., int.class) has null for a klass field
2644 return TypePtr::NULL_PTR;
2645 }
2646 // Fold up the load of the hidden field
2647 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2648 }
2649 // non-constant mirror, so we can't tell what's going on
2650 }
2651 if (!tinst->is_loaded())
2652 return _type; // Bail out if not loaded
2653 if (offset == oopDesc::klass_offset_in_bytes()) {
2654 return tinst->as_klass_type(true);
2655 }
2656 }
2657
2658 // Check for loading klass from an array
2659 const TypeAryPtr* tary = tp->isa_aryptr();
2660 if (tary != nullptr &&
2661 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2662 return tary->as_klass_type(true);
2663 }
2664
2665 // Check for loading klass from an array klass
2666 const TypeKlassPtr *tkls = tp->isa_klassptr();
2667 if (tkls != nullptr && !StressReflectiveCode) {
2668 if (!tkls->is_loaded())
2669 return _type; // Bail out if not loaded
2670 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2671 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2672 // // Always returning precise element type is incorrect,
2673 // // e.g., element type could be object and array may contain strings
2674 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2675
2676 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2677 // according to the element type's subclassing.
2678 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2679 }
2680 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2681 tkls->offset() == in_bytes(Klass::super_offset())) {
2682 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2683 // The field is Klass::_super. Return its (constant) value.
2684 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2685 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2686 }
2687 }
2688
2689 if (tkls != nullptr && !UseSecondarySupersCache
2690 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2691 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2692 return TypePtr::NULL_PTR;
2693 }
2694
2695 // Bailout case
2696 return LoadNode::Value(phase);
2697 }
2698
2699 //------------------------------Identity---------------------------------------
2700 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2701 // Also feed through the klass in Allocate(...klass...)._klass.
2702 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2703 return klass_identity_common(phase);
2704 }
2705
2706 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2707 Node* x = LoadNode::Identity(phase);
2708 if (x != this) return x;
2709
2710 // Take apart the address into an oop and offset.
2711 // Return 'this' if we cannot.
2712 Node* adr = in(MemNode::Address);
2713 intptr_t offset = 0;
2714 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2715 if (base == nullptr) return this;
2716 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2717 if (toop == nullptr) return this;
2718
2719 // Step over potential GC barrier for OopHandle resolve
2720 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2721 if (bs->is_gc_barrier_node(base)) {
2722 base = bs->step_over_gc_barrier(base);
2723 }
2724
2725 // We can fetch the klass directly through an AllocateNode.
2726 // This works even if the klass is not constant (clone or newArray).
2727 if (offset == oopDesc::klass_offset_in_bytes()) {
2728 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2729 if (allocated_klass != nullptr) {
2730 return allocated_klass;
2731 }
2732 }
2733
2734 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2735 // See inline_native_Class_query for occurrences of these patterns.
2736 // Java Example: x.getClass().isAssignableFrom(y)
2737 //
2738 // This improves reflective code, often making the Class
2739 // mirror go completely dead. (Current exception: Class
2740 // mirrors may appear in debug info, but we could clean them out by
2741 // introducing a new debug info operator for Klass.java_mirror).
2742
2743 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2744 && offset == java_lang_Class::klass_offset()) {
2745 if (base->is_Load()) {
2746 Node* base2 = base->in(MemNode::Address);
2747 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2748 Node* adr2 = base2->in(MemNode::Address);
2749 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2750 // TODO 8366668 Re-enable this for arrays
2751 if (tkls != nullptr && !tkls->empty()
2752 && ((tkls->isa_instklassptr() && !tkls->is_instklassptr()->might_be_an_array()) || (tkls->isa_aryklassptr() && false))
2753 && adr2->is_AddP()
2754 ) {
2755 int mirror_field = in_bytes(Klass::java_mirror_offset());
2756 if (tkls->offset() == mirror_field) {
2757 return adr2->in(AddPNode::Base);
2758 }
2759 }
2760 }
2761 }
2762 }
2763
2764 return this;
2765 }
2766
2767 LoadNode* LoadNode::clone_pinned() const {
2768 LoadNode* ld = clone()->as_Load();
2769 ld->_control_dependency = UnknownControl;
2770 return ld;
2771 }
2772
2773
2774 //------------------------------Value------------------------------------------
2775 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2776 const Type *t = klass_value_common(phase);
2777 if (t == Type::TOP)
2778 return t;
2779
2780 return t->make_narrowklass();
2781 }
2782
2783 //------------------------------Identity---------------------------------------
2784 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2785 // Also feed through the klass in Allocate(...klass...)._klass.
2786 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2787 Node *x = klass_identity_common(phase);
2788
2789 const Type *t = phase->type( x );
2790 if( t == Type::TOP ) return x;
2791 if( t->isa_narrowklass()) return x;
2792 assert (!t->isa_narrowoop(), "no narrow oop here");
2793
2794 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2795 }
2796
2797 //------------------------------Value-----------------------------------------
2798 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2799 // Either input is TOP ==> the result is TOP
2800 const Type *t1 = phase->type( in(MemNode::Memory) );
2801 if( t1 == Type::TOP ) return Type::TOP;
2802 Node *adr = in(MemNode::Address);
2803 const Type *t2 = phase->type( adr );
2804 if( t2 == Type::TOP ) return Type::TOP;
2805 const TypePtr *tp = t2->is_ptr();
2806 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2807 const TypeAryPtr *tap = tp->isa_aryptr();
2808 if( !tap ) return _type;
2809 return tap->size();
2810 }
2811
2812 //-------------------------------Ideal---------------------------------------
2813 // Feed through the length in AllocateArray(...length...)._length.
2814 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2815 Node* p = MemNode::Ideal_common(phase, can_reshape);
2816 if (p) return (p == NodeSentinel) ? nullptr : p;
2817
2818 // Take apart the address into an oop and offset.
2819 // Return 'this' if we cannot.
2820 Node* adr = in(MemNode::Address);
2821 intptr_t offset = 0;
2822 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2823 if (base == nullptr) return nullptr;
2824 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2825 if (tary == nullptr) return nullptr;
2826
2827 // We can fetch the length directly through an AllocateArrayNode.
2828 // This works even if the length is not constant (clone or newArray).
2829 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2830 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2831 if (alloc != nullptr) {
2832 Node* allocated_length = alloc->Ideal_length();
2833 Node* len = alloc->make_ideal_length(tary, phase);
2834 if (allocated_length != len) {
2835 // New CastII improves on this.
2836 return len;
2837 }
2838 }
2839 }
2840
2841 return nullptr;
2842 }
2843
2844 //------------------------------Identity---------------------------------------
2845 // Feed through the length in AllocateArray(...length...)._length.
2846 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2847 Node* x = LoadINode::Identity(phase);
2848 if (x != this) return x;
2849
2850 // Take apart the address into an oop and offset.
2851 // Return 'this' if we cannot.
2852 Node* adr = in(MemNode::Address);
2853 intptr_t offset = 0;
2854 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2855 if (base == nullptr) return this;
2856 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2857 if (tary == nullptr) return this;
2858
2859 // We can fetch the length directly through an AllocateArrayNode.
2860 // This works even if the length is not constant (clone or newArray).
2861 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2862 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2863 if (alloc != nullptr) {
2864 Node* allocated_length = alloc->Ideal_length();
2865 // Do not allow make_ideal_length to allocate a CastII node.
2866 Node* len = alloc->make_ideal_length(tary, phase, false);
2867 if (allocated_length == len) {
2868 // Return allocated_length only if it would not be improved by a CastII.
2869 return allocated_length;
2870 }
2871 }
2872 }
2873
2874 return this;
2875
2876 }
2877
2878 //=============================================================================
2879 //---------------------------StoreNode::make-----------------------------------
2880 // Polymorphic factory method:
2881 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo, bool require_atomic_access) {
2882 assert((mo == unordered || mo == release), "unexpected");
2883 Compile* C = gvn.C;
2884 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2885 ctl != nullptr, "raw memory operations should have control edge");
2886
2887 switch (bt) {
2888 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2889 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2890 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2891 case T_CHAR:
2892 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2893 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2894 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2895 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2896 case T_METADATA:
2897 case T_ADDRESS:
2898 case T_OBJECT:
2899 #ifdef _LP64
2900 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2901 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2902 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2903 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2904 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2905 adr->bottom_type()->isa_rawptr())) {
2906 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2907 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2908 }
2909 #endif
2910 {
2911 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2912 }
2913 default:
2914 ShouldNotReachHere();
2915 return (StoreNode*)nullptr;
2916 }
2917 }
2918
2919 //--------------------------bottom_type----------------------------------------
2920 const Type *StoreNode::bottom_type() const {
2921 return Type::MEMORY;
2922 }
2923
2924 //------------------------------hash-------------------------------------------
2925 uint StoreNode::hash() const {
2926 // unroll addition of interesting fields
2927 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2928
2929 // Since they are not commoned, do not hash them:
2930 return NO_HASH;
2931 }
2932
2933 // Link together multiple stores (B/S/C/I) into a longer one.
2934 //
2935 // Example: _store = StoreB[i+3]
2936 //
2937 // RangeCheck[i+0] RangeCheck[i+0]
2938 // StoreB[i+0]
2939 // RangeCheck[i+3] RangeCheck[i+3]
2940 // StoreB[i+1] --> pass: fail:
2941 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
2942 // StoreB[i+3]
2943 //
2944 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2945 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2946 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2947 // failing path.
2948 //
2949 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2950 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2951 // and possibly no RangeChecks remain between the stores.
2952 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2953 // and those later RangeChecks can be removed. Example:
2954 //
2955 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
2956 // StoreB[i+0] StoreB[i+0] <- first store
2957 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
2958 // StoreB[i+1] StoreB[i+1] <- second store
2959 // RangeCheck[i+2] --> removed
2960 // StoreB[i+2] StoreB[i+2]
2961 // RangeCheck[i+3] --> removed
2962 // StoreB[i+3] StoreB[i+3] <- last store
2963 //
2964 // Thus, it is a common pattern that between the first and last store in a chain
2965 // of adjacent stores there remains exactly one RangeCheck, located between the
2966 // first and the second store (e.g. RangeCheck[i+3]).
2967 //
2968 class MergePrimitiveStores : public StackObj {
2969 private:
2970 PhaseGVN* const _phase;
2971 StoreNode* const _store;
2972 // State machine with initial state Unknown
2973 // Allowed transitions:
2974 // Unknown -> Const
2975 // Unknown -> Platform
2976 // Unknown -> Reverse
2977 // Unknown -> NotAdjacent
2978 // Const -> Const
2979 // Const -> NotAdjacent
2980 // Platform -> Platform
2981 // Platform -> NotAdjacent
2982 // Reverse -> Reverse
2983 // Reverse -> NotAdjacent
2984 // NotAdjacent -> NotAdjacent
2985 enum ValueOrder : uint8_t {
2986 Unknown, // Initial state
2987 Const, // Input values are const
2988 Platform, // Platform order
2989 Reverse, // Reverse platform order
2990 NotAdjacent // Not adjacent
2991 };
2992 ValueOrder _value_order;
2993
2994 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
2995
2996 public:
2997 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
2998 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
2999 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
3000 {}
3001
3002 StoreNode* run();
3003
3004 private:
3005 bool is_compatible_store(const StoreNode* other_store) const;
3006 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
3007 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
3008 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
3009 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
3010 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
3011
3012 class Status {
3013 private:
3014 StoreNode* _found_store;
3015 bool _found_range_check;
3016
3017 Status(StoreNode* found_store, bool found_range_check)
3018 : _found_store(found_store), _found_range_check(found_range_check) {}
3019
3020 public:
3021 StoreNode* found_store() const { return _found_store; }
3022 bool found_range_check() const { return _found_range_check; }
3023 static Status make_failure() { return Status(nullptr, false); }
3024
3025 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
3026 if (cfg_status == CFGStatus::Failure) {
3027 return Status::make_failure();
3028 }
3029 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
3030 }
3031
3032 #ifndef PRODUCT
3033 void print_on(outputStream* st) const {
3034 if (_found_store == nullptr) {
3035 st->print_cr("None");
3036 } else {
3037 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
3038 _found_range_check ? "RC" : "no-RC");
3039 }
3040 }
3041 #endif
3042 };
3043
3044 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
3045 Status find_adjacent_use_store(const StoreNode* def_store) const;
3046 Status find_adjacent_def_store(const StoreNode* use_store) const;
3047 Status find_use_store(const StoreNode* def_store) const;
3048 Status find_def_store(const StoreNode* use_store) const;
3049 Status find_use_store_unidirectional(const StoreNode* def_store) const;
3050 Status find_def_store_unidirectional(const StoreNode* use_store) const;
3051
3052 void collect_merge_list(Node_List& merge_list) const;
3053 Node* make_merged_input_value(const Node_List& merge_list);
3054 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
3055
3056 #ifndef PRODUCT
3057 // Access to TraceMergeStores tags
3058 bool is_trace(TraceMergeStores::Tag tag) const {
3059 return _trace_tags.at(tag);
3060 }
3061
3062 bool is_trace_basic() const {
3063 return is_trace(TraceMergeStores::Tag::BASIC);
3064 }
3065
3066 bool is_trace_pointer_parsing() const {
3067 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
3068 }
3069
3070 bool is_trace_pointer_aliasing() const {
3071 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
3072 }
3073
3074 bool is_trace_pointer_adjacency() const {
3075 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
3076 }
3077
3078 bool is_trace_success() const {
3079 return is_trace(TraceMergeStores::Tag::SUCCESS);
3080 }
3081 #endif
3082
3083 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
3084 };
3085
3086 StoreNode* MergePrimitiveStores::run() {
3087 // Check for B/S/C/I
3088 int opc = _store->Opcode();
3089 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
3090 return nullptr;
3091 }
3092
3093 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
3094
3095 // The _store must be the "last" store in a chain. If we find a use we could merge with
3096 // then that use or a store further down is the "last" store.
3097 Status status_use = find_adjacent_use_store(_store);
3098 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
3099 if (status_use.found_store() != nullptr) {
3100 return nullptr;
3101 }
3102
3103 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
3104 Status status_def = find_adjacent_def_store(_store);
3105 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
3106 Node* def_store = status_def.found_store();
3107 if (def_store == nullptr) {
3108 return nullptr;
3109 }
3110
3111 // Initialize value order
3112 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
3113 _store->in(MemNode::ValueIn),
3114 _store->memory_size());
3115 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
3116
3117 ResourceMark rm;
3118 Node_List merge_list;
3119 collect_merge_list(merge_list);
3120
3121 Node* merged_input_value = make_merged_input_value(merge_list);
3122 if (merged_input_value == nullptr) { return nullptr; }
3123
3124 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3125
3126 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
3127
3128 return merged_store;
3129 }
3130
3131 // Check compatibility between _store and other_store.
3132 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
3133 int opc = _store->Opcode();
3134 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3135
3136 if (other_store == nullptr ||
3137 _store->Opcode() != other_store->Opcode()) {
3138 return false;
3139 }
3140
3141 return true;
3142 }
3143
3144 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3145 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3146 use_store->in(MemNode::ValueIn),
3147 def_store->memory_size())) {
3148 return false;
3149 }
3150
3151 ResourceMark rm;
3152 #ifndef PRODUCT
3153 const TraceMemPointer trace(is_trace_pointer_parsing(),
3154 is_trace_pointer_aliasing(),
3155 is_trace_pointer_adjacency(),
3156 true);
3157 #endif
3158 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
3159 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
3160 return pointer_def.is_adjacent_to_and_before(pointer_use);
3161 }
3162
3163 // Check input values n1 and n2 can be merged and return the value order
3164 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
3165 const int memory_size) const {
3166 // Pattern: [n1 = ConI, n2 = ConI]
3167 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
3168 return ValueOrder::Const;
3169 }
3170
3171 Node const *base_n2;
3172 jint shift_n2;
3173 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
3174 return ValueOrder::NotAdjacent;
3175 }
3176 Node const *base_n1;
3177 jint shift_n1;
3178 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
3179 return ValueOrder::NotAdjacent;
3180 }
3181
3182 int bits_per_store = memory_size * 8;
3183 if (base_n1 != base_n2 ||
3184 abs(shift_n1 - shift_n2) != bits_per_store ||
3185 shift_n1 % bits_per_store != 0) {
3186 // Values are not adjacent
3187 return ValueOrder::NotAdjacent;
3188 }
3189
3190 // Detect value order
3191 #ifdef VM_LITTLE_ENDIAN
3192 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3193 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3194 #else
3195 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3196 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3197 #endif
3198 }
3199
3200 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3201 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3202
3203 switch (input_value_order) {
3204 case ValueOrder::NotAdjacent:
3205 return false;
3206 case ValueOrder::Reverse:
3207 if (memory_size != 1 ||
3208 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3209 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3210 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3211 // ReverseBytes are not supported by platform
3212 return false;
3213 }
3214 // fall-through.
3215 case ValueOrder::Const:
3216 case ValueOrder::Platform:
3217 if (_value_order == ValueOrder::Unknown) {
3218 // Initial state is Unknown, and we find a valid input value order
3219 return true;
3220 }
3221 // The value order can not be changed
3222 return _value_order == input_value_order;
3223 case ValueOrder::Unknown:
3224 default:
3225 ShouldNotReachHere();
3226 }
3227 return false;
3228 }
3229
3230 // Detect pattern: n = base_out >> shift_out
3231 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3232 assert(n != nullptr, "precondition");
3233
3234 int opc = n->Opcode();
3235 if (opc == Op_ConvL2I) {
3236 n = n->in(1);
3237 opc = n->Opcode();
3238 }
3239
3240 if ((opc == Op_RShiftI ||
3241 opc == Op_RShiftL ||
3242 opc == Op_URShiftI ||
3243 opc == Op_URShiftL) &&
3244 n->in(2)->is_ConI()) {
3245 base_out = n->in(1);
3246 shift_out = n->in(2)->get_int();
3247 // The shift must be positive:
3248 return shift_out >= 0;
3249 }
3250
3251 if (phase->type(n)->isa_int() != nullptr ||
3252 phase->type(n)->isa_long() != nullptr) {
3253 // (base >> 0)
3254 base_out = n;
3255 shift_out = 0;
3256 return true;
3257 }
3258 return false;
3259 }
3260
3261 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3262 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3263 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3264
3265 Node* ctrl_use = use_store->in(MemNode::Control);
3266 Node* ctrl_def = def_store->in(MemNode::Control);
3267 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3268 return CFGStatus::Failure;
3269 }
3270
3271 if (ctrl_use == ctrl_def) {
3272 // Same ctrl -> no RangeCheck in between.
3273 // Check: use_store must be the only use of def_store.
3274 if (def_store->outcnt() > 1) {
3275 return CFGStatus::Failure;
3276 }
3277 return CFGStatus::SuccessNoRangeCheck;
3278 }
3279
3280 // Different ctrl -> could have RangeCheck in between.
3281 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3282 // 2. ctrl separated by RangeCheck.
3283 if (def_store->outcnt() != 2) {
3284 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3285 }
3286 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3287 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3288 if (merge_mem == nullptr ||
3289 merge_mem->outcnt() != 1) {
3290 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3291 }
3292 if (!ctrl_use->is_IfProj() ||
3293 !ctrl_use->in(0)->is_RangeCheck() ||
3294 ctrl_use->in(0)->outcnt() != 2) {
3295 return CFGStatus::Failure; // Not RangeCheck.
3296 }
3297 ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3298 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3299 if (trap != merge_mem->unique_out() ||
3300 ctrl_use->in(0)->in(0) != ctrl_def) {
3301 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3302 }
3303
3304 return CFGStatus::SuccessWithRangeCheck;
3305 }
3306
3307 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3308 Status status_use = find_use_store(def_store);
3309 StoreNode* use_store = status_use.found_store();
3310 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3311 return Status::make_failure();
3312 }
3313 return status_use;
3314 }
3315
3316 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3317 Status status_def = find_def_store(use_store);
3318 StoreNode* def_store = status_def.found_store();
3319 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3320 return Status::make_failure();
3321 }
3322 return status_def;
3323 }
3324
3325 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3326 Status status_use = find_use_store_unidirectional(def_store);
3327
3328 #ifdef ASSERT
3329 StoreNode* use_store = status_use.found_store();
3330 if (use_store != nullptr) {
3331 Status status_def = find_def_store_unidirectional(use_store);
3332 assert(status_def.found_store() == def_store &&
3333 status_def.found_range_check() == status_use.found_range_check(),
3334 "find_use_store and find_def_store must be symmetric");
3335 }
3336 #endif
3337
3338 return status_use;
3339 }
3340
3341 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3342 Status status_def = find_def_store_unidirectional(use_store);
3343
3344 #ifdef ASSERT
3345 StoreNode* def_store = status_def.found_store();
3346 if (def_store != nullptr) {
3347 Status status_use = find_use_store_unidirectional(def_store);
3348 assert(status_use.found_store() == use_store &&
3349 status_use.found_range_check() == status_def.found_range_check(),
3350 "find_use_store and find_def_store must be symmetric");
3351 }
3352 #endif
3353
3354 return status_def;
3355 }
3356
3357 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3358 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3359
3360 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3361 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3362 if (is_compatible_store(use_store)) {
3363 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3364 }
3365 }
3366
3367 return Status::make_failure();
3368 }
3369
3370 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3371 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3372
3373 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3374 if (!is_compatible_store(def_store)) {
3375 return Status::make_failure();
3376 }
3377
3378 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3379 }
3380
3381 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3382 // The merged store can be at most 8 bytes.
3383 const uint merge_list_max_size = 8 / _store->memory_size();
3384 assert(merge_list_max_size >= 2 &&
3385 merge_list_max_size <= 8 &&
3386 is_power_of_2(merge_list_max_size),
3387 "must be 2, 4 or 8");
3388
3389 // Traverse up the chain of adjacent def stores.
3390 StoreNode* current = _store;
3391 merge_list.push(current);
3392 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3393 Status status = find_adjacent_def_store(current);
3394 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3395
3396 current = status.found_store();
3397 if (current != nullptr) {
3398 merge_list.push(current);
3399
3400 // We can have at most one RangeCheck.
3401 if (status.found_range_check()) {
3402 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3403 break;
3404 }
3405 }
3406 }
3407
3408 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3409
3410 // Truncate the merge_list to a power of 2.
3411 const uint pow2size = round_down_power_of_2(merge_list.size());
3412 assert(pow2size >= 2, "must be merging at least 2 stores");
3413 while (merge_list.size() > pow2size) { merge_list.pop(); }
3414
3415 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3416 }
3417
3418 // Merge the input values of the smaller stores to a single larger input value.
3419 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3420 int new_memory_size = _store->memory_size() * merge_list.size();
3421 Node* first = merge_list.at(merge_list.size()-1);
3422 Node* merged_input_value = nullptr;
3423 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3424 assert(_value_order == ValueOrder::Const, "must match");
3425 // Pattern: [ConI, ConI, ...] -> new constant
3426 jlong con = 0;
3427 jlong bits_per_store = _store->memory_size() * 8;
3428 jlong mask = (((jlong)1) << bits_per_store) - 1;
3429 for (uint i = 0; i < merge_list.size(); i++) {
3430 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3431 #ifdef VM_LITTLE_ENDIAN
3432 con = con << bits_per_store;
3433 con = con | (mask & con_i);
3434 #else // VM_LITTLE_ENDIAN
3435 con_i = (mask & con_i) << (i * bits_per_store);
3436 con = con | con_i;
3437 #endif // VM_LITTLE_ENDIAN
3438 }
3439 merged_input_value = _phase->longcon(con);
3440 } else {
3441 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3442 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3443 // | |
3444 // _store first
3445 //
3446 Node* hi = _store->in(MemNode::ValueIn);
3447 Node* lo = first->in(MemNode::ValueIn);
3448 #ifndef VM_LITTLE_ENDIAN
3449 // `_store` and `first` are swapped in the diagram above
3450 swap(hi, lo);
3451 #endif // !VM_LITTLE_ENDIAN
3452 if (_value_order == ValueOrder::Reverse) {
3453 swap(hi, lo);
3454 }
3455 Node const* hi_base;
3456 jint hi_shift;
3457 merged_input_value = lo;
3458 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3459 assert(is_true, "must detect con RShift");
3460 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3461 // look through
3462 merged_input_value = merged_input_value->in(1);
3463 }
3464 if (merged_input_value != hi_base) {
3465 // merged_input_value is not the base
3466 return nullptr;
3467 }
3468 }
3469
3470 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3471 // Example:
3472 //
3473 // long base = ...;
3474 // a[0] = (byte)(base >> 0);
3475 // a[1] = (byte)(base >> 8);
3476 //
3477 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3478 }
3479
3480 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3481 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3482 "merged_input_value is either int or long, and new_memory_size is small enough");
3483
3484 if (_value_order == ValueOrder::Reverse) {
3485 assert(_store->memory_size() == 1, "only implemented for bytes");
3486 if (new_memory_size == 8) {
3487 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3488 } else if (new_memory_size == 4) {
3489 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3490 } else {
3491 assert(new_memory_size == 2, "sanity check");
3492 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3493 }
3494 }
3495 return merged_input_value;
3496 }
3497
3498 // //
3499 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3500 // | | | | | | //
3501 // | | | | +---------------+ | //
3502 // | | | | | | | //
3503 // | | +---------+ | | +---------------+ //
3504 // | | | | | | | | //
3505 // +--------------+ | | v1 +------------------------------+ | | v1 //
3506 // | | | | | | | | | | | | //
3507 // RangeCheck first_store RangeCheck | | first_store //
3508 // | | | | | | | //
3509 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3510 // | | ===> | | | //
3511 // +--------------+ | a2 v2 | | | //
3512 // | | | | | | | | //
3513 // | second_store | | | //
3514 // | | | | | [v1 v2 ... vn] //
3515 // ... ... | | | | //
3516 // | | | | | v //
3517 // +--------------+ | an vn +--------------+ | | merged_input_value //
3518 // | | | | | | | | //
3519 // last_store (= _store) merged_store //
3520 // //
3521 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3522 Node* first_store = merge_list.at(merge_list.size()-1);
3523 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3524 Node* first_mem = first_store->in(MemNode::Memory);
3525 Node* first_adr = first_store->in(MemNode::Address);
3526
3527 const TypePtr* new_adr_type = _store->adr_type();
3528
3529 int new_memory_size = _store->memory_size() * merge_list.size();
3530 BasicType bt = T_ILLEGAL;
3531 switch (new_memory_size) {
3532 case 2: bt = T_SHORT; break;
3533 case 4: bt = T_INT; break;
3534 case 8: bt = T_LONG; break;
3535 }
3536
3537 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3538 new_adr_type, merged_input_value, bt, MemNode::unordered);
3539
3540 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3541 // are all on the same slice. Hence, we need no barriers.
3542 merged_store->set_mismatched_access();
3543
3544 // Constants above may now also be be packed -> put candidate on worklist
3545 _phase->is_IterGVN()->_worklist.push(first_mem);
3546
3547 return merged_store;
3548 }
3549
3550 #ifndef PRODUCT
3551 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3552 stringStream ss;
3553 ss.print_cr("[TraceMergeStores]: Replace");
3554 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3555 merge_list.at(i)->dump("\n", false, &ss);
3556 }
3557 ss.print_cr("[TraceMergeStores]: with");
3558 merged_input_value->dump("\n", false, &ss);
3559 merged_store->dump("\n", false, &ss);
3560 tty->print("%s", ss.as_string());
3561 }
3562 #endif
3563
3564 //------------------------------Ideal------------------------------------------
3565 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3566 // When a store immediately follows a relevant allocation/initialization,
3567 // try to capture it into the initialization, or hoist it above.
3568 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3569 Node* p = MemNode::Ideal_common(phase, can_reshape);
3570 if (p) return (p == NodeSentinel) ? nullptr : p;
3571
3572 Node* mem = in(MemNode::Memory);
3573 Node* address = in(MemNode::Address);
3574 Node* value = in(MemNode::ValueIn);
3575 // Back-to-back stores to same address? Fold em up. Generally
3576 // unsafe if I have intervening uses...
3577 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
3578 Node* st = mem;
3579 // If Store 'st' has more than one use, we cannot fold 'st' away.
3580 // For example, 'st' might be the final state at a conditional
3581 // return. Or, 'st' might be used by some node which is live at
3582 // the same time 'st' is live, which might be unschedulable. So,
3583 // require exactly ONE user until such time as we clone 'mem' for
3584 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3585 // true).
3586 while (st->is_Store() && st->outcnt() == 1) {
3587 // Looking at a dead closed cycle of memory?
3588 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3589 assert(Opcode() == st->Opcode() ||
3590 st->Opcode() == Op_StoreVector ||
3591 Opcode() == Op_StoreVector ||
3592 st->Opcode() == Op_StoreVectorScatter ||
3593 Opcode() == Op_StoreVectorScatter ||
3594 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3595 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3596 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3597 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
3598 (st->adr_type()->isa_aryptr() && st->adr_type()->is_aryptr()->is_flat()) || // TODO 8343835
3599 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3600 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3601
3602 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3603 st->as_Store()->memory_size() <= this->memory_size()) {
3604 Node* use = st->raw_out(0);
3605 if (phase->is_IterGVN()) {
3606 phase->is_IterGVN()->rehash_node_delayed(use);
3607 }
3608 // It's OK to do this in the parser, since DU info is always accurate,
3609 // and the parser always refers to nodes via SafePointNode maps.
3610 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3611 return this;
3612 }
3613 st = st->in(MemNode::Memory);
3614 }
3615 }
3616
3617
3618 // Capture an unaliased, unconditional, simple store into an initializer.
3619 // Or, if it is independent of the allocation, hoist it above the allocation.
3620 if (ReduceFieldZeroing && /*can_reshape &&*/
3621 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3622 InitializeNode* init = mem->in(0)->as_Initialize();
3623 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3624 if (offset > 0) {
3625 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3626 // If the InitializeNode captured me, it made a raw copy of me,
3627 // and I need to disappear.
3628 if (moved != nullptr) {
3629 // %%% hack to ensure that Ideal returns a new node:
3630 mem = MergeMemNode::make(mem);
3631 return mem; // fold me away
3632 }
3633 }
3634 }
3635
3636 // Fold reinterpret cast into memory operation:
3637 // StoreX mem (MoveY2X v) => StoreY mem v
3638 if (value->is_Move()) {
3639 const Type* vt = value->in(1)->bottom_type();
3640 if (has_reinterpret_variant(vt)) {
3641 if (phase->C->post_loop_opts_phase()) {
3642 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3643 } else {
3644 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3645 }
3646 }
3647 }
3648
3649 if (MergeStores && UseUnalignedAccesses) {
3650 if (phase->C->merge_stores_phase()) {
3651 MergePrimitiveStores merge(phase, this);
3652 Node* progress = merge.run();
3653 if (progress != nullptr) { return progress; }
3654 } else {
3655 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3656 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3657 // the stores, and we merge the wrong sequence of stores.
3658 // Example:
3659 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3660 // Apply MergeStores:
3661 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3662 // Remove more RangeChecks:
3663 // StoreI [ StoreL ] StoreI
3664 // But now it would have been better to do this instead:
3665 // [ StoreL ] [ StoreL ]
3666 phase->C->record_for_merge_stores_igvn(this);
3667 }
3668 }
3669
3670 return nullptr; // No further progress
3671 }
3672
3673 //------------------------------Value-----------------------------------------
3674 const Type* StoreNode::Value(PhaseGVN* phase) const {
3675 // Either input is TOP ==> the result is TOP
3676 const Type *t1 = phase->type( in(MemNode::Memory) );
3677 if( t1 == Type::TOP ) return Type::TOP;
3678 const Type *t2 = phase->type( in(MemNode::Address) );
3679 if( t2 == Type::TOP ) return Type::TOP;
3680 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3681 if( t3 == Type::TOP ) return Type::TOP;
3682 return Type::MEMORY;
3683 }
3684
3685 //------------------------------Identity---------------------------------------
3686 // Remove redundant stores:
3687 // Store(m, p, Load(m, p)) changes to m.
3688 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3689 Node* StoreNode::Identity(PhaseGVN* phase) {
3690 Node* mem = in(MemNode::Memory);
3691 Node* adr = in(MemNode::Address);
3692 Node* val = in(MemNode::ValueIn);
3693
3694 Node* result = this;
3695
3696 // Load then Store? Then the Store is useless
3697 if (val->is_Load() &&
3698 val->in(MemNode::Address)->eqv_uncast(adr) &&
3699 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3700 val->as_Load()->store_Opcode() == Opcode()) {
3701 // Ensure vector type is the same
3702 if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3703 result = mem;
3704 }
3705 }
3706
3707 // Two stores in a row of the same value?
3708 if (result == this &&
3709 mem->is_Store() &&
3710 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3711 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3712 mem->Opcode() == Opcode()) {
3713 if (!is_StoreVector()) {
3714 result = mem;
3715 } else {
3716 const StoreVectorNode* store_vector = as_StoreVector();
3717 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3718 const Node* store_indices = store_vector->indices();
3719 const Node* mem_indices = mem_vector->indices();
3720 const Node* store_mask = store_vector->mask();
3721 const Node* mem_mask = mem_vector->mask();
3722 // Ensure types, indices, and masks match
3723 if (store_vector->vect_type() == mem_vector->vect_type() &&
3724 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3725 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3726 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3727 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3728 result = mem;
3729 }
3730 }
3731 }
3732
3733 // Store of zero anywhere into a freshly-allocated object?
3734 // Then the store is useless.
3735 // (It must already have been captured by the InitializeNode.)
3736 if (result == this && ReduceFieldZeroing) {
3737 // a newly allocated object is already all-zeroes everywhere
3738 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
3739 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::InitValue) == val)) {
3740 result = mem;
3741 }
3742
3743 if (result == this && phase->type(val)->is_zero_type()) {
3744 // the store may also apply to zero-bits in an earlier object
3745 Node* prev_mem = find_previous_store(phase);
3746 // Steps (a), (b): Walk past independent stores to find an exact match.
3747 if (prev_mem != nullptr) {
3748 Node* prev_val = can_see_stored_value(prev_mem, phase);
3749 if (prev_val != nullptr && prev_val == val) {
3750 // prev_val and val might differ by a cast; it would be good
3751 // to keep the more informative of the two.
3752 result = mem;
3753 }
3754 }
3755 }
3756 }
3757
3758 PhaseIterGVN* igvn = phase->is_IterGVN();
3759 if (result != this && igvn != nullptr) {
3760 MemBarNode* trailing = trailing_membar();
3761 if (trailing != nullptr) {
3762 #ifdef ASSERT
3763 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3764 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3765 #endif
3766 trailing->remove(igvn);
3767 }
3768 }
3769
3770 return result;
3771 }
3772
3773 //------------------------------match_edge-------------------------------------
3774 // Do we Match on this edge index or not? Match only memory & value
3775 uint StoreNode::match_edge(uint idx) const {
3776 return idx == MemNode::Address || idx == MemNode::ValueIn;
3777 }
3778
3779 //------------------------------cmp--------------------------------------------
3780 // Do not common stores up together. They generally have to be split
3781 // back up anyways, so do not bother.
3782 bool StoreNode::cmp( const Node &n ) const {
3783 return (&n == this); // Always fail except on self
3784 }
3785
3786 //------------------------------Ideal_masked_input-----------------------------
3787 // Check for a useless mask before a partial-word store
3788 // (StoreB ... (AndI valIn conIa) )
3789 // If (conIa & mask == mask) this simplifies to
3790 // (StoreB ... (valIn) )
3791 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3792 Node *val = in(MemNode::ValueIn);
3793 if( val->Opcode() == Op_AndI ) {
3794 const TypeInt *t = phase->type( val->in(2) )->isa_int();
3795 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3796 set_req_X(MemNode::ValueIn, val->in(1), phase);
3797 return this;
3798 }
3799 }
3800 return nullptr;
3801 }
3802
3803
3804 //------------------------------Ideal_sign_extended_input----------------------
3805 // Check for useless sign-extension before a partial-word store
3806 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3807 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3808 // (StoreB ... (v))
3809 // If (conIL > conIR) under some conditions, it can be simplified into
3810 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3811 // This case happens when the value of the store was itself a left shift, that
3812 // gets merged into the inner left shift of the sign-extension. For instance,
3813 // if we have
3814 // array_of_shorts[0] = (short)(v << 2)
3815 // We get a structure such as:
3816 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3817 // that is simplified into
3818 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3819 // It is thus useful to handle cases where conIL > conIR. But this simplification
3820 // does not always hold. Let's see in which cases it's valid.
3821 //
3822 // Let's assume we have the following 32 bits integer v:
3823 // +----------------------------------+
3824 // | v[0..31] |
3825 // +----------------------------------+
3826 // 31 0
3827 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3828 // potentially different magnitudes.
3829 // We denote num_rejected_bits the number of bits of the discarded part. In this
3830 // case, num_rejected_bits == 24.
3831 //
3832 // Statement (proved further below in case analysis):
3833 // Given:
3834 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3835 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3836 // - conIL >= conIR
3837 // - num_rejected_bits >= conIR
3838 // Then this form:
3839 // (RShiftI _ (LShiftI _ v conIL) conIR)
3840 // can be replaced with this form:
3841 // (LShiftI _ v (conIL-conIR))
3842 //
3843 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3844 // have to be correct, as the higher bits are rejected / truncated by the store.
3845 //
3846 // The hypotheses
3847 // 0 <= conIL < BitsPerJavaInteger
3848 // 0 <= conIR < BitsPerJavaInteger
3849 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3850 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3851 // to v << 1).
3852 //
3853 //
3854 // If you don't like case analysis, jump after the conclusion.
3855 // ### Case 1 : conIL == conIR
3856 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3857 // If we do the shift left then right by 24 bits, we get:
3858 // after: v << 24
3859 // +---------+------------------------+
3860 // | v[0..7] | 0 |
3861 // +---------+------------------------+
3862 // 31 24 23 0
3863 // after: (v << 24) >> 24
3864 // +------------------------+---------+
3865 // | sign bit | v[0..7] |
3866 // +------------------------+---------+
3867 // 31 8 7 0
3868 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3869 // result) are the same before and after, so, indeed, simplifying is correct.
3870
3871 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3872 // If we do the shift left then right by 22 bits, we get:
3873 // after: v << 22
3874 // +---------+------------------------+
3875 // | v[0..9] | 0 |
3876 // +---------+------------------------+
3877 // 31 22 21 0
3878 // after: (v << 22) >> 22
3879 // +------------------------+---------+
3880 // | sign bit | v[0..9] |
3881 // +------------------------+---------+
3882 // 31 10 9 0
3883 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3884 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3885 // still correct.
3886
3887 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3888 // If we do the shift left then right by 26 bits, we get:
3889 // after: v << 26
3890 // +---------+------------------------+
3891 // | v[0..5] | 0 |
3892 // +---------+------------------------+
3893 // 31 26 25 0
3894 // after: (v << 26) >> 26
3895 // +------------------------+---------+
3896 // | sign bit | v[0..5] |
3897 // +------------------------+---------+
3898 // 31 6 5 0
3899 // The non-rejected bits are made of
3900 // - 0-5 => the bits 0 to 5 of v
3901 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3902 // Simplifying this as v is not correct.
3903 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3904 //
3905 // ### Case 2: conIL > conIR
3906 // ###### Case 2.1: num_rejected_bits == conIR
3907 // We take conIL == 26 for this example.
3908 // after: v << 26
3909 // +---------+------------------------+
3910 // | v[0..5] | 0 |
3911 // +---------+------------------------+
3912 // 31 26 25 0
3913 // after: (v << 26) >> 24
3914 // +------------------+---------+-----+
3915 // | sign bit | v[0..5] | 0 |
3916 // +------------------+---------+-----+
3917 // 31 8 7 2 1 0
3918 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3919 // The bits 6 and 7 of v have been thrown away after the shift left.
3920 // The simplification is still correct.
3921 //
3922 // ###### Case 2.2: num_rejected_bits > conIR.
3923 // Let's say conIL == 26 and conIR == 22.
3924 // after: v << 26
3925 // +---------+------------------------+
3926 // | v[0..5] | 0 |
3927 // +---------+------------------------+
3928 // 31 26 25 0
3929 // after: (v << 26) >> 22
3930 // +------------------+---------+-----+
3931 // | sign bit | v[0..5] | 0 |
3932 // +------------------+---------+-----+
3933 // 31 10 9 4 3 0
3934 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3935 // - 0-3 => 0
3936 // - 4-7 => bits 0 to 3 of v
3937 // The simplification is still correct.
3938 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3939 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3940 //
3941 // ###### But! Case 2.3: num_rejected_bits < conIR.
3942 // Let's see that this case is not as easy to simplify.
3943 // Let's say conIL == 28 and conIR == 26.
3944 // after: v << 28
3945 // +---------+------------------------+
3946 // | v[0..3] | 0 |
3947 // +---------+------------------------+
3948 // 31 28 27 0
3949 // after: (v << 28) >> 26
3950 // +------------------+---------+-----+
3951 // | sign bit | v[0..3] | 0 |
3952 // +------------------+---------+-----+
3953 // 31 6 5 2 1 0
3954 // The non-rejected bits are made of
3955 // - 0-1 => 0
3956 // - 2-5 => the bits 0 to 3 of v
3957 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3958 // Simplifying this as (v << 2) is not correct.
3959 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3960 //
3961 // ### Conclusion:
3962 // Our hypotheses are indeed sufficient:
3963 // - 0 <= conIL < BitsPerJavaInteger
3964 // - 0 <= conIR < BitsPerJavaInteger
3965 // - conIL >= conIR
3966 // - num_rejected_bits >= conIR
3967 //
3968 // ### A rationale without case analysis:
3969 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
3970 // zeroes are added. After the shift right, conIR lower bits of the previous result
3971 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3972 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3973 // the point of the simplification is to get an expression of the form
3974 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3975 // simplification is not correct if conIL < conIR.
3976 //
3977 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3978 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3979 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3980 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3981 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3982 //
3983 // We do not treat the case conIL < conIR here since the point of this function is
3984 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3985 // of treating conIL > conIR comes from the cases where the sign-extended value is
3986 // also left-shift expression. Computing the sign-extension of a right-shift expression
3987 // doesn't yield a situation such as
3988 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3989 // where conIL < conIR.
3990 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3991 Node* shr = in(MemNode::ValueIn);
3992 if (shr->Opcode() == Op_RShiftI) {
3993 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
3994 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
3995 Node* shl = shr->in(1);
3996 if (shl->Opcode() == Op_LShiftI) {
3997 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
3998 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
3999 if (conIL->get_con() == conIR->get_con()) {
4000 set_req_X(MemNode::ValueIn, shl->in(1), phase);
4001 return this;
4002 }
4003 if (conIL->get_con() > conIR->get_con()) {
4004 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
4005 set_req_X(MemNode::ValueIn, new_shl, phase);
4006 return this;
4007 }
4008 }
4009 }
4010 }
4011 }
4012 return nullptr;
4013 }
4014
4015 //------------------------------value_never_loaded-----------------------------------
4016 // Determine whether there are any possible loads of the value stored.
4017 // For simplicity, we actually check if there are any loads from the
4018 // address stored to, not just for loads of the value stored by this node.
4019 //
4020 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
4021 Node *adr = in(Address);
4022 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
4023 if (adr_oop == nullptr)
4024 return false;
4025 if (!adr_oop->is_known_instance_field())
4026 return false; // if not a distinct instance, there may be aliases of the address
4027 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
4028 Node *use = adr->fast_out(i);
4029 if (use->is_Load() || use->is_LoadStore()) {
4030 return false;
4031 }
4032 }
4033 return true;
4034 }
4035
4036 MemBarNode* StoreNode::trailing_membar() const {
4037 if (is_release()) {
4038 MemBarNode* trailing_mb = nullptr;
4039 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4040 Node* u = fast_out(i);
4041 if (u->is_MemBar()) {
4042 if (u->as_MemBar()->trailing_store()) {
4043 assert(u->Opcode() == Op_MemBarVolatile, "");
4044 assert(trailing_mb == nullptr, "only one");
4045 trailing_mb = u->as_MemBar();
4046 #ifdef ASSERT
4047 Node* leading = u->as_MemBar()->leading_membar();
4048 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4049 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
4050 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
4051 #endif
4052 } else {
4053 assert(u->as_MemBar()->standalone(), "");
4054 }
4055 }
4056 }
4057 return trailing_mb;
4058 }
4059 return nullptr;
4060 }
4061
4062
4063 //=============================================================================
4064 //------------------------------Ideal------------------------------------------
4065 // If the store is from an AND mask that leaves the low bits untouched, then
4066 // we can skip the AND operation. If the store is from a sign-extension
4067 // (a left shift, then right shift) we can skip both.
4068 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
4069 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
4070 if( progress != nullptr ) return progress;
4071
4072 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
4073 if( progress != nullptr ) return progress;
4074
4075 // Finally check the default case
4076 return StoreNode::Ideal(phase, can_reshape);
4077 }
4078
4079 //=============================================================================
4080 //------------------------------Ideal------------------------------------------
4081 // If the store is from an AND mask that leaves the low bits untouched, then
4082 // we can skip the AND operation
4083 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
4084 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
4085 if( progress != nullptr ) return progress;
4086
4087 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
4088 if( progress != nullptr ) return progress;
4089
4090 // Finally check the default case
4091 return StoreNode::Ideal(phase, can_reshape);
4092 }
4093
4094 //=============================================================================
4095 //----------------------------------SCMemProjNode------------------------------
4096 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
4097 {
4098 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
4099 return Type::TOP;
4100 }
4101 return bottom_type();
4102 }
4103
4104 //=============================================================================
4105 //----------------------------------LoadStoreNode------------------------------
4106 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
4107 : Node(required),
4108 _type(rt),
4109 _adr_type(at),
4110 _barrier_data(0)
4111 {
4112 init_req(MemNode::Control, c );
4113 init_req(MemNode::Memory , mem);
4114 init_req(MemNode::Address, adr);
4115 init_req(MemNode::ValueIn, val);
4116 init_class_id(Class_LoadStore);
4117 }
4118
4119 //------------------------------Value-----------------------------------------
4120 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
4121 // Either input is TOP ==> the result is TOP
4122 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
4123 return Type::TOP;
4124 }
4125 const Type* t = phase->type(in(MemNode::Memory));
4126 if (t == Type::TOP) {
4127 return Type::TOP;
4128 }
4129 t = phase->type(in(MemNode::Address));
4130 if (t == Type::TOP) {
4131 return Type::TOP;
4132 }
4133 t = phase->type(in(MemNode::ValueIn));
4134 if (t == Type::TOP) {
4135 return Type::TOP;
4136 }
4137 return bottom_type();
4138 }
4139
4140 uint LoadStoreNode::ideal_reg() const {
4141 return _type->ideal_reg();
4142 }
4143
4144 // This method conservatively checks if the result of a LoadStoreNode is
4145 // used, that is, if it returns true, then it is definitely the case that
4146 // the result of the node is not needed.
4147 // For example, GetAndAdd can be matched into a lock_add instead of a
4148 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
4149 bool LoadStoreNode::result_not_used() const {
4150 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4151 Node *x = fast_out(i);
4152 if (x->Opcode() == Op_SCMemProj) {
4153 continue;
4154 }
4155 if (x->bottom_type() == TypeTuple::MEMBAR &&
4156 !x->is_Call() &&
4157 x->Opcode() != Op_Blackhole) {
4158 continue;
4159 }
4160 return false;
4161 }
4162 return true;
4163 }
4164
4165 MemBarNode* LoadStoreNode::trailing_membar() const {
4166 MemBarNode* trailing = nullptr;
4167 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4168 Node* u = fast_out(i);
4169 if (u->is_MemBar()) {
4170 if (u->as_MemBar()->trailing_load_store()) {
4171 assert(u->Opcode() == Op_MemBarAcquire, "");
4172 assert(trailing == nullptr, "only one");
4173 trailing = u->as_MemBar();
4174 #ifdef ASSERT
4175 Node* leading = trailing->leading_membar();
4176 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4177 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
4178 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
4179 #endif
4180 } else {
4181 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
4182 }
4183 }
4184 }
4185
4186 return trailing;
4187 }
4188
4189 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4190
4191 //=============================================================================
4192 //----------------------------------LoadStoreConditionalNode--------------------
4193 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4194 init_req(ExpectedIn, ex );
4195 }
4196
4197 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4198 // Either input is TOP ==> the result is TOP
4199 const Type* t = phase->type(in(ExpectedIn));
4200 if (t == Type::TOP) {
4201 return Type::TOP;
4202 }
4203 return LoadStoreNode::Value(phase);
4204 }
4205
4206 //=============================================================================
4207 //-------------------------------adr_type--------------------------------------
4208 const TypePtr* ClearArrayNode::adr_type() const {
4209 Node *adr = in(3);
4210 if (adr == nullptr) return nullptr; // node is dead
4211 return MemNode::calculate_adr_type(adr->bottom_type());
4212 }
4213
4214 //------------------------------match_edge-------------------------------------
4215 // Do we Match on this edge index or not? Do not match memory
4216 uint ClearArrayNode::match_edge(uint idx) const {
4217 return idx > 1;
4218 }
4219
4220 //------------------------------Identity---------------------------------------
4221 // Clearing a zero length array does nothing
4222 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4223 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4224 }
4225
4226 //------------------------------Idealize---------------------------------------
4227 // Clearing a short array is faster with stores
4228 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4229 // Already know this is a large node, do not try to ideal it
4230 if (_is_large) return nullptr;
4231
4232 const int unit = BytesPerLong;
4233 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4234 if (!t) return nullptr;
4235 if (!t->is_con()) return nullptr;
4236 intptr_t raw_count = t->get_con();
4237 intptr_t size = raw_count;
4238 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4239 // Clearing nothing uses the Identity call.
4240 // Negative clears are possible on dead ClearArrays
4241 // (see jck test stmt114.stmt11402.val).
4242 if (size <= 0 || size % unit != 0) return nullptr;
4243 intptr_t count = size / unit;
4244 // Length too long; communicate this to matchers and assemblers.
4245 // Assemblers are responsible to produce fast hardware clears for it.
4246 if (size > InitArrayShortSize) {
4247 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
4248 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4249 return nullptr;
4250 }
4251 if (!IdealizeClearArrayNode) return nullptr;
4252 Node *mem = in(1);
4253 if( phase->type(mem)==Type::TOP ) return nullptr;
4254 Node *adr = in(3);
4255 const Type* at = phase->type(adr);
4256 if( at==Type::TOP ) return nullptr;
4257 const TypePtr* atp = at->isa_ptr();
4258 // adjust atp to be the correct array element address type
4259 if (atp == nullptr) atp = TypePtr::BOTTOM;
4260 else atp = atp->add_offset(Type::OffsetBot);
4261 // Get base for derived pointer purposes
4262 if( adr->Opcode() != Op_AddP ) Unimplemented();
4263 Node *base = adr->in(1);
4264
4265 Node *val = in(4);
4266 Node *off = phase->MakeConX(BytesPerLong);
4267 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4268 count--;
4269 while( count-- ) {
4270 mem = phase->transform(mem);
4271 adr = phase->transform(new AddPNode(base,adr,off));
4272 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4273 }
4274 return mem;
4275 }
4276
4277 //----------------------------step_through----------------------------------
4278 // Return allocation input memory edge if it is different instance
4279 // or itself if it is the one we are looking for.
4280 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4281 Node* n = *np;
4282 assert(n->is_ClearArray(), "sanity");
4283 intptr_t offset;
4284 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4285 // This method is called only before Allocate nodes are expanded
4286 // during macro nodes expansion. Before that ClearArray nodes are
4287 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4288 // Allocate nodes are expanded) which follows allocations.
4289 assert(alloc != nullptr, "should have allocation");
4290 if (alloc->_idx == instance_id) {
4291 // Can not bypass initialization of the instance we are looking for.
4292 return false;
4293 }
4294 // Otherwise skip it.
4295 InitializeNode* init = alloc->initialization();
4296 if (init != nullptr)
4297 *np = init->in(TypeFunc::Memory);
4298 else
4299 *np = alloc->in(TypeFunc::Memory);
4300 return true;
4301 }
4302
4303 //----------------------------clear_memory-------------------------------------
4304 // Generate code to initialize object storage to zero.
4305 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4306 Node* val,
4307 Node* raw_val,
4308 intptr_t start_offset,
4309 Node* end_offset,
4310 PhaseGVN* phase) {
4311 intptr_t offset = start_offset;
4312
4313 int unit = BytesPerLong;
4314 if ((offset % unit) != 0) {
4315 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4316 adr = phase->transform(adr);
4317 const TypePtr* atp = TypeRawPtr::BOTTOM;
4318 if (val != nullptr) {
4319 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4320 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4321 } else {
4322 assert(raw_val == nullptr, "val may not be null");
4323 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4324 }
4325 mem = phase->transform(mem);
4326 offset += BytesPerInt;
4327 }
4328 assert((offset % unit) == 0, "");
4329
4330 // Initialize the remaining stuff, if any, with a ClearArray.
4331 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
4332 }
4333
4334 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4335 Node* raw_val,
4336 Node* start_offset,
4337 Node* end_offset,
4338 PhaseGVN* phase) {
4339 if (start_offset == end_offset) {
4340 // nothing to do
4341 return mem;
4342 }
4343
4344 int unit = BytesPerLong;
4345 Node* zbase = start_offset;
4346 Node* zend = end_offset;
4347
4348 // Scale to the unit required by the CPU:
4349 if (!Matcher::init_array_count_is_in_bytes) {
4350 Node* shift = phase->intcon(exact_log2(unit));
4351 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4352 zend = phase->transform(new URShiftXNode(zend, shift) );
4353 }
4354
4355 // Bulk clear double-words
4356 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4357 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4358 if (raw_val == nullptr) {
4359 raw_val = phase->MakeConX(0);
4360 }
4361 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
4362 return phase->transform(mem);
4363 }
4364
4365 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4366 Node* val,
4367 Node* raw_val,
4368 intptr_t start_offset,
4369 intptr_t end_offset,
4370 PhaseGVN* phase) {
4371 if (start_offset == end_offset) {
4372 // nothing to do
4373 return mem;
4374 }
4375
4376 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4377 intptr_t done_offset = end_offset;
4378 if ((done_offset % BytesPerLong) != 0) {
4379 done_offset -= BytesPerInt;
4380 }
4381 if (done_offset > start_offset) {
4382 mem = clear_memory(ctl, mem, dest, val, raw_val,
4383 start_offset, phase->MakeConX(done_offset), phase);
4384 }
4385 if (done_offset < end_offset) { // emit the final 32-bit store
4386 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4387 adr = phase->transform(adr);
4388 const TypePtr* atp = TypeRawPtr::BOTTOM;
4389 if (val != nullptr) {
4390 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4391 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4392 } else {
4393 assert(raw_val == nullptr, "val may not be null");
4394 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4395 }
4396 mem = phase->transform(mem);
4397 done_offset += BytesPerInt;
4398 }
4399 assert(done_offset == end_offset, "");
4400 return mem;
4401 }
4402
4403 //=============================================================================
4404 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4405 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4406 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4407 #ifdef ASSERT
4408 , _pair_idx(0)
4409 #endif
4410 {
4411 init_class_id(Class_MemBar);
4412 Node* top = C->top();
4413 init_req(TypeFunc::I_O,top);
4414 init_req(TypeFunc::FramePtr,top);
4415 init_req(TypeFunc::ReturnAdr,top);
4416 if (precedent != nullptr)
4417 init_req(TypeFunc::Parms, precedent);
4418 }
4419
4420 //------------------------------cmp--------------------------------------------
4421 uint MemBarNode::hash() const { return NO_HASH; }
4422 bool MemBarNode::cmp( const Node &n ) const {
4423 return (&n == this); // Always fail except on self
4424 }
4425
4426 //------------------------------make-------------------------------------------
4427 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4428 switch (opcode) {
4429 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4430 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4431 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4432 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4433 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4434 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4435 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4436 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4437 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4438 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4439 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4440 case Op_Initialize: return new InitializeNode(C, atp, pn);
4441 default: ShouldNotReachHere(); return nullptr;
4442 }
4443 }
4444
4445 void MemBarNode::remove(PhaseIterGVN *igvn) {
4446 if (outcnt() != 2) {
4447 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4448 assert(outcnt() == 1, "Only control then");
4449 }
4450 if (trailing_store() || trailing_load_store()) {
4451 MemBarNode* leading = leading_membar();
4452 if (leading != nullptr) {
4453 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4454 leading->remove(igvn);
4455 }
4456 }
4457 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4458 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4459 }
4460 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4461 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4462 }
4463 }
4464
4465 //------------------------------Ideal------------------------------------------
4466 // Return a node which is more "ideal" than the current node. Strip out
4467 // control copies
4468 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4469 if (remove_dead_region(phase, can_reshape)) return this;
4470 // Don't bother trying to transform a dead node
4471 if (in(0) && in(0)->is_top()) {
4472 return nullptr;
4473 }
4474
4475 bool progress = false;
4476 // Eliminate volatile MemBars for scalar replaced objects.
4477 if (can_reshape && req() == (Precedent+1)) {
4478 bool eliminate = false;
4479 int opc = Opcode();
4480 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4481 // Volatile field loads and stores.
4482 Node* my_mem = in(MemBarNode::Precedent);
4483 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4484 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4485 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4486 // replace this Precedent (decodeN) with the Load instead.
4487 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4488 Node* load_node = my_mem->in(1);
4489 set_req(MemBarNode::Precedent, load_node);
4490 phase->is_IterGVN()->_worklist.push(my_mem);
4491 my_mem = load_node;
4492 } else {
4493 assert(my_mem->unique_out() == this, "sanity");
4494 assert(!trailing_load_store(), "load store node can't be eliminated");
4495 del_req(Precedent);
4496 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4497 my_mem = nullptr;
4498 }
4499 progress = true;
4500 }
4501 if (my_mem != nullptr && my_mem->is_Mem()) {
4502 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4503 // Check for scalar replaced object reference.
4504 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4505 t_oop->offset() != Type::OffsetBot &&
4506 t_oop->offset() != Type::OffsetTop) {
4507 eliminate = true;
4508 }
4509 }
4510 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4511 // Final field stores.
4512 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4513 if ((alloc != nullptr) && alloc->is_Allocate() &&
4514 alloc->as_Allocate()->does_not_escape_thread()) {
4515 // The allocated object does not escape.
4516 eliminate = true;
4517 }
4518 }
4519 if (eliminate) {
4520 // Replace MemBar projections by its inputs.
4521 PhaseIterGVN* igvn = phase->is_IterGVN();
4522 remove(igvn);
4523 // Must return either the original node (now dead) or a new node
4524 // (Do not return a top here, since that would break the uniqueness of top.)
4525 return new ConINode(TypeInt::ZERO);
4526 }
4527 }
4528 return progress ? this : nullptr;
4529 }
4530
4531 //------------------------------Value------------------------------------------
4532 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4533 if( !in(0) ) return Type::TOP;
4534 if( phase->type(in(0)) == Type::TOP )
4535 return Type::TOP;
4536 return TypeTuple::MEMBAR;
4537 }
4538
4539 //------------------------------match------------------------------------------
4540 // Construct projections for memory.
4541 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
4542 switch (proj->_con) {
4543 case TypeFunc::Control:
4544 case TypeFunc::Memory:
4545 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4546 }
4547 ShouldNotReachHere();
4548 return nullptr;
4549 }
4550
4551 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4552 trailing->_kind = TrailingStore;
4553 leading->_kind = LeadingStore;
4554 #ifdef ASSERT
4555 trailing->_pair_idx = leading->_idx;
4556 leading->_pair_idx = leading->_idx;
4557 #endif
4558 }
4559
4560 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4561 trailing->_kind = TrailingLoadStore;
4562 leading->_kind = LeadingLoadStore;
4563 #ifdef ASSERT
4564 trailing->_pair_idx = leading->_idx;
4565 leading->_pair_idx = leading->_idx;
4566 #endif
4567 }
4568
4569 MemBarNode* MemBarNode::trailing_membar() const {
4570 ResourceMark rm;
4571 Node* trailing = (Node*)this;
4572 VectorSet seen;
4573 Node_Stack multis(0);
4574 do {
4575 Node* c = trailing;
4576 uint i = 0;
4577 do {
4578 trailing = nullptr;
4579 for (; i < c->outcnt(); i++) {
4580 Node* next = c->raw_out(i);
4581 if (next != c && next->is_CFG()) {
4582 if (c->is_MultiBranch()) {
4583 if (multis.node() == c) {
4584 multis.set_index(i+1);
4585 } else {
4586 multis.push(c, i+1);
4587 }
4588 }
4589 trailing = next;
4590 break;
4591 }
4592 }
4593 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4594 break;
4595 }
4596 while (multis.size() > 0) {
4597 c = multis.node();
4598 i = multis.index();
4599 if (i < c->req()) {
4600 break;
4601 }
4602 multis.pop();
4603 }
4604 } while (multis.size() > 0);
4605 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4606
4607 MemBarNode* mb = trailing->as_MemBar();
4608 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4609 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4610 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4611 return mb;
4612 }
4613
4614 MemBarNode* MemBarNode::leading_membar() const {
4615 ResourceMark rm;
4616 VectorSet seen;
4617 Node_Stack regions(0);
4618 Node* leading = in(0);
4619 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4620 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4621 leading = nullptr;
4622 while (regions.size() > 0 && leading == nullptr) {
4623 Node* r = regions.node();
4624 uint i = regions.index();
4625 if (i < r->req()) {
4626 leading = r->in(i);
4627 regions.set_index(i+1);
4628 } else {
4629 regions.pop();
4630 }
4631 }
4632 if (leading == nullptr) {
4633 assert(regions.size() == 0, "all paths should have been tried");
4634 return nullptr;
4635 }
4636 }
4637 if (leading->is_Region()) {
4638 regions.push(leading, 2);
4639 leading = leading->in(1);
4640 } else {
4641 leading = leading->in(0);
4642 }
4643 }
4644 #ifdef ASSERT
4645 Unique_Node_List wq;
4646 wq.push((Node*)this);
4647 uint found = 0;
4648 for (uint i = 0; i < wq.size(); i++) {
4649 Node* n = wq.at(i);
4650 if (n->is_Region()) {
4651 for (uint j = 1; j < n->req(); j++) {
4652 Node* in = n->in(j);
4653 if (in != nullptr && !in->is_top()) {
4654 wq.push(in);
4655 }
4656 }
4657 } else {
4658 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4659 assert(n == leading, "consistency check failed");
4660 found++;
4661 } else {
4662 Node* in = n->in(0);
4663 if (in != nullptr && !in->is_top()) {
4664 wq.push(in);
4665 }
4666 }
4667 }
4668 }
4669 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4670 #endif
4671 if (leading == nullptr) {
4672 return nullptr;
4673 }
4674 MemBarNode* mb = leading->as_MemBar();
4675 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4676 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4677 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4678 return mb;
4679 }
4680
4681
4682 //===========================InitializeNode====================================
4683 // SUMMARY:
4684 // This node acts as a memory barrier on raw memory, after some raw stores.
4685 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4686 // The Initialize can 'capture' suitably constrained stores as raw inits.
4687 // It can coalesce related raw stores into larger units (called 'tiles').
4688 // It can avoid zeroing new storage for memory units which have raw inits.
4689 // At macro-expansion, it is marked 'complete', and does not optimize further.
4690 //
4691 // EXAMPLE:
4692 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4693 // ctl = incoming control; mem* = incoming memory
4694 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4695 // First allocate uninitialized memory and fill in the header:
4696 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4697 // ctl := alloc.Control; mem* := alloc.Memory*
4698 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4699 // Then initialize to zero the non-header parts of the raw memory block:
4700 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4701 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4702 // After the initialize node executes, the object is ready for service:
4703 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4704 // Suppose its body is immediately initialized as {1,2}:
4705 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4706 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4707 // mem.SLICE(#short[*]) := store2
4708 //
4709 // DETAILS:
4710 // An InitializeNode collects and isolates object initialization after
4711 // an AllocateNode and before the next possible safepoint. As a
4712 // memory barrier (MemBarNode), it keeps critical stores from drifting
4713 // down past any safepoint or any publication of the allocation.
4714 // Before this barrier, a newly-allocated object may have uninitialized bits.
4715 // After this barrier, it may be treated as a real oop, and GC is allowed.
4716 //
4717 // The semantics of the InitializeNode include an implicit zeroing of
4718 // the new object from object header to the end of the object.
4719 // (The object header and end are determined by the AllocateNode.)
4720 //
4721 // Certain stores may be added as direct inputs to the InitializeNode.
4722 // These stores must update raw memory, and they must be to addresses
4723 // derived from the raw address produced by AllocateNode, and with
4724 // a constant offset. They must be ordered by increasing offset.
4725 // The first one is at in(RawStores), the last at in(req()-1).
4726 // Unlike most memory operations, they are not linked in a chain,
4727 // but are displayed in parallel as users of the rawmem output of
4728 // the allocation.
4729 //
4730 // (See comments in InitializeNode::capture_store, which continue
4731 // the example given above.)
4732 //
4733 // When the associated Allocate is macro-expanded, the InitializeNode
4734 // may be rewritten to optimize collected stores. A ClearArrayNode
4735 // may also be created at that point to represent any required zeroing.
4736 // The InitializeNode is then marked 'complete', prohibiting further
4737 // capturing of nearby memory operations.
4738 //
4739 // During macro-expansion, all captured initializations which store
4740 // constant values of 32 bits or smaller are coalesced (if advantageous)
4741 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4742 // initialized in fewer memory operations. Memory words which are
4743 // covered by neither tiles nor non-constant stores are pre-zeroed
4744 // by explicit stores of zero. (The code shape happens to do all
4745 // zeroing first, then all other stores, with both sequences occurring
4746 // in order of ascending offsets.)
4747 //
4748 // Alternatively, code may be inserted between an AllocateNode and its
4749 // InitializeNode, to perform arbitrary initialization of the new object.
4750 // E.g., the object copying intrinsics insert complex data transfers here.
4751 // The initialization must then be marked as 'complete' disable the
4752 // built-in zeroing semantics and the collection of initializing stores.
4753 //
4754 // While an InitializeNode is incomplete, reads from the memory state
4755 // produced by it are optimizable if they match the control edge and
4756 // new oop address associated with the allocation/initialization.
4757 // They return a stored value (if the offset matches) or else zero.
4758 // A write to the memory state, if it matches control and address,
4759 // and if it is to a constant offset, may be 'captured' by the
4760 // InitializeNode. It is cloned as a raw memory operation and rewired
4761 // inside the initialization, to the raw oop produced by the allocation.
4762 // Operations on addresses which are provably distinct (e.g., to
4763 // other AllocateNodes) are allowed to bypass the initialization.
4764 //
4765 // The effect of all this is to consolidate object initialization
4766 // (both arrays and non-arrays, both piecewise and bulk) into a
4767 // single location, where it can be optimized as a unit.
4768 //
4769 // Only stores with an offset less than TrackedInitializationLimit words
4770 // will be considered for capture by an InitializeNode. This puts a
4771 // reasonable limit on the complexity of optimized initializations.
4772
4773 //---------------------------InitializeNode------------------------------------
4774 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4775 : MemBarNode(C, adr_type, rawoop),
4776 _is_complete(Incomplete), _does_not_escape(false)
4777 {
4778 init_class_id(Class_Initialize);
4779
4780 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4781 assert(in(RawAddress) == rawoop, "proper init");
4782 // Note: allocation() can be null, for secondary initialization barriers
4783 }
4784
4785 // Since this node is not matched, it will be processed by the
4786 // register allocator. Declare that there are no constraints
4787 // on the allocation of the RawAddress edge.
4788 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4789 // This edge should be set to top, by the set_complete. But be conservative.
4790 if (idx == InitializeNode::RawAddress)
4791 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4792 return RegMask::Empty;
4793 }
4794
4795 Node* InitializeNode::memory(uint alias_idx) {
4796 Node* mem = in(Memory);
4797 if (mem->is_MergeMem()) {
4798 return mem->as_MergeMem()->memory_at(alias_idx);
4799 } else {
4800 // incoming raw memory is not split
4801 return mem;
4802 }
4803 }
4804
4805 bool InitializeNode::is_non_zero() {
4806 if (is_complete()) return false;
4807 remove_extra_zeroes();
4808 return (req() > RawStores);
4809 }
4810
4811 void InitializeNode::set_complete(PhaseGVN* phase) {
4812 assert(!is_complete(), "caller responsibility");
4813 _is_complete = Complete;
4814
4815 // After this node is complete, it contains a bunch of
4816 // raw-memory initializations. There is no need for
4817 // it to have anything to do with non-raw memory effects.
4818 // Therefore, tell all non-raw users to re-optimize themselves,
4819 // after skipping the memory effects of this initialization.
4820 PhaseIterGVN* igvn = phase->is_IterGVN();
4821 if (igvn) igvn->add_users_to_worklist(this);
4822 }
4823
4824 // convenience function
4825 // return false if the init contains any stores already
4826 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4827 InitializeNode* init = initialization();
4828 if (init == nullptr || init->is_complete()) {
4829 return false;
4830 }
4831 init->remove_extra_zeroes();
4832 // for now, if this allocation has already collected any inits, bail:
4833 if (init->is_non_zero()) return false;
4834 init->set_complete(phase);
4835 return true;
4836 }
4837
4838 void InitializeNode::remove_extra_zeroes() {
4839 if (req() == RawStores) return;
4840 Node* zmem = zero_memory();
4841 uint fill = RawStores;
4842 for (uint i = fill; i < req(); i++) {
4843 Node* n = in(i);
4844 if (n->is_top() || n == zmem) continue; // skip
4845 if (fill < i) set_req(fill, n); // compact
4846 ++fill;
4847 }
4848 // delete any empty spaces created:
4849 while (fill < req()) {
4850 del_req(fill);
4851 }
4852 }
4853
4854 // Helper for remembering which stores go with which offsets.
4855 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4856 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
4857 intptr_t offset = -1;
4858 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4859 phase, offset);
4860 if (base == nullptr) return -1; // something is dead,
4861 if (offset < 0) return -1; // dead, dead
4862 return offset;
4863 }
4864
4865 // Helper for proving that an initialization expression is
4866 // "simple enough" to be folded into an object initialization.
4867 // Attempts to prove that a store's initial value 'n' can be captured
4868 // within the initialization without creating a vicious cycle, such as:
4869 // { Foo p = new Foo(); p.next = p; }
4870 // True for constants and parameters and small combinations thereof.
4871 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4872 ResourceMark rm;
4873 Unique_Node_List worklist;
4874 worklist.push(value);
4875
4876 uint complexity_limit = 20;
4877 for (uint j = 0; j < worklist.size(); j++) {
4878 if (j >= complexity_limit) {
4879 return false; // Bail out if processed too many nodes
4880 }
4881
4882 Node* n = worklist.at(j);
4883 if (n == nullptr) continue; // (can this really happen?)
4884 if (n->is_Proj()) n = n->in(0);
4885 if (n == this) return false; // found a cycle
4886 if (n->is_Con()) continue;
4887 if (n->is_Start()) continue; // params, etc., are OK
4888 if (n->is_Root()) continue; // even better
4889
4890 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4891 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4892 continue;
4893 }
4894
4895 Node* ctl = n->in(0);
4896 if (ctl != nullptr && !ctl->is_top()) {
4897 if (ctl->is_Proj()) ctl = ctl->in(0);
4898 if (ctl == this) return false;
4899
4900 // If we already know that the enclosing memory op is pinned right after
4901 // the init, then any control flow that the store has picked up
4902 // must have preceded the init, or else be equal to the init.
4903 // Even after loop optimizations (which might change control edges)
4904 // a store is never pinned *before* the availability of its inputs.
4905 if (!MemNode::all_controls_dominate(n, this)) {
4906 return false; // failed to prove a good control
4907 }
4908 }
4909
4910 // Check data edges for possible dependencies on 'this'.
4911 for (uint i = 1; i < n->req(); i++) {
4912 Node* m = n->in(i);
4913 if (m == nullptr || m == n || m->is_top()) continue;
4914
4915 // Only process data inputs once
4916 worklist.push(m);
4917 }
4918 }
4919
4920 return true;
4921 }
4922
4923 // Here are all the checks a Store must pass before it can be moved into
4924 // an initialization. Returns zero if a check fails.
4925 // On success, returns the (constant) offset to which the store applies,
4926 // within the initialized memory.
4927 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4928 const int FAIL = 0;
4929 if (st->req() != MemNode::ValueIn + 1)
4930 return FAIL; // an inscrutable StoreNode (card mark?)
4931 Node* ctl = st->in(MemNode::Control);
4932 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4933 return FAIL; // must be unconditional after the initialization
4934 Node* mem = st->in(MemNode::Memory);
4935 if (!(mem->is_Proj() && mem->in(0) == this))
4936 return FAIL; // must not be preceded by other stores
4937 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4938 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4939 !bs->can_initialize_object(st)) {
4940 return FAIL;
4941 }
4942 Node* adr = st->in(MemNode::Address);
4943 intptr_t offset;
4944 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4945 if (alloc == nullptr)
4946 return FAIL; // inscrutable address
4947 if (alloc != allocation())
4948 return FAIL; // wrong allocation! (store needs to float up)
4949 int size_in_bytes = st->memory_size();
4950 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4951 return FAIL; // mismatched access
4952 }
4953 Node* val = st->in(MemNode::ValueIn);
4954
4955 if (!detect_init_independence(val, phase))
4956 return FAIL; // stored value must be 'simple enough'
4957
4958 // The Store can be captured only if nothing after the allocation
4959 // and before the Store is using the memory location that the store
4960 // overwrites.
4961 bool failed = false;
4962 // If is_complete_with_arraycopy() is true the shape of the graph is
4963 // well defined and is safe so no need for extra checks.
4964 if (!is_complete_with_arraycopy()) {
4965 // We are going to look at each use of the memory state following
4966 // the allocation to make sure nothing reads the memory that the
4967 // Store writes.
4968 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4969 int alias_idx = phase->C->get_alias_index(t_adr);
4970 ResourceMark rm;
4971 Unique_Node_List mems;
4972 mems.push(mem);
4973 Node* unique_merge = nullptr;
4974 for (uint next = 0; next < mems.size(); ++next) {
4975 Node *m = mems.at(next);
4976 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4977 Node *n = m->fast_out(j);
4978 if (n->outcnt() == 0) {
4979 continue;
4980 }
4981 if (n == st) {
4982 continue;
4983 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4984 // If the control of this use is different from the control
4985 // of the Store which is right after the InitializeNode then
4986 // this node cannot be between the InitializeNode and the
4987 // Store.
4988 continue;
4989 } else if (n->is_MergeMem()) {
4990 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4991 // We can hit a MergeMemNode (that will likely go away
4992 // later) that is a direct use of the memory state
4993 // following the InitializeNode on the same slice as the
4994 // store node that we'd like to capture. We need to check
4995 // the uses of the MergeMemNode.
4996 mems.push(n);
4997 }
4998 } else if (n->is_Mem()) {
4999 Node* other_adr = n->in(MemNode::Address);
5000 if (other_adr == adr) {
5001 failed = true;
5002 break;
5003 } else {
5004 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
5005 if (other_t_adr != nullptr) {
5006 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
5007 if (other_alias_idx == alias_idx) {
5008 // A load from the same memory slice as the store right
5009 // after the InitializeNode. We check the control of the
5010 // object/array that is loaded from. If it's the same as
5011 // the store control then we cannot capture the store.
5012 assert(!n->is_Store(), "2 stores to same slice on same control?");
5013 Node* base = other_adr;
5014 if (base->is_Phi()) {
5015 // In rare case, base may be a PhiNode and it may read
5016 // the same memory slice between InitializeNode and store.
5017 failed = true;
5018 break;
5019 }
5020 assert(base->is_AddP(), "should be addp but is %s", base->Name());
5021 base = base->in(AddPNode::Base);
5022 if (base != nullptr) {
5023 base = base->uncast();
5024 if (base->is_Proj() && base->in(0) == alloc) {
5025 failed = true;
5026 break;
5027 }
5028 }
5029 }
5030 }
5031 }
5032 } else {
5033 failed = true;
5034 break;
5035 }
5036 }
5037 }
5038 }
5039 if (failed) {
5040 if (!can_reshape) {
5041 // We decided we couldn't capture the store during parsing. We
5042 // should try again during the next IGVN once the graph is
5043 // cleaner.
5044 phase->C->record_for_igvn(st);
5045 }
5046 return FAIL;
5047 }
5048
5049 return offset; // success
5050 }
5051
5052 // Find the captured store in(i) which corresponds to the range
5053 // [start..start+size) in the initialized object.
5054 // If there is one, return its index i. If there isn't, return the
5055 // negative of the index where it should be inserted.
5056 // Return 0 if the queried range overlaps an initialization boundary
5057 // or if dead code is encountered.
5058 // If size_in_bytes is zero, do not bother with overlap checks.
5059 int InitializeNode::captured_store_insertion_point(intptr_t start,
5060 int size_in_bytes,
5061 PhaseValues* phase) {
5062 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
5063
5064 if (is_complete())
5065 return FAIL; // arraycopy got here first; punt
5066
5067 assert(allocation() != nullptr, "must be present");
5068
5069 // no negatives, no header fields:
5070 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
5071
5072 // after a certain size, we bail out on tracking all the stores:
5073 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5074 if (start >= ti_limit) return FAIL;
5075
5076 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
5077 if (i >= limit) return -(int)i; // not found; here is where to put it
5078
5079 Node* st = in(i);
5080 intptr_t st_off = get_store_offset(st, phase);
5081 if (st_off < 0) {
5082 if (st != zero_memory()) {
5083 return FAIL; // bail out if there is dead garbage
5084 }
5085 } else if (st_off > start) {
5086 // ...we are done, since stores are ordered
5087 if (st_off < start + size_in_bytes) {
5088 return FAIL; // the next store overlaps
5089 }
5090 return -(int)i; // not found; here is where to put it
5091 } else if (st_off < start) {
5092 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
5093 if (size_in_bytes != 0 &&
5094 start < st_off + MAX_STORE &&
5095 start < st_off + st->as_Store()->memory_size()) {
5096 return FAIL; // the previous store overlaps
5097 }
5098 } else {
5099 if (size_in_bytes != 0 &&
5100 st->as_Store()->memory_size() != size_in_bytes) {
5101 return FAIL; // mismatched store size
5102 }
5103 return i;
5104 }
5105
5106 ++i;
5107 }
5108 }
5109
5110 // Look for a captured store which initializes at the offset 'start'
5111 // with the given size. If there is no such store, and no other
5112 // initialization interferes, then return zero_memory (the memory
5113 // projection of the AllocateNode).
5114 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
5115 PhaseValues* phase) {
5116 assert(stores_are_sane(phase), "");
5117 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5118 if (i == 0) {
5119 return nullptr; // something is dead
5120 } else if (i < 0) {
5121 return zero_memory(); // just primordial zero bits here
5122 } else {
5123 Node* st = in(i); // here is the store at this position
5124 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
5125 return st;
5126 }
5127 }
5128
5129 // Create, as a raw pointer, an address within my new object at 'offset'.
5130 Node* InitializeNode::make_raw_address(intptr_t offset,
5131 PhaseGVN* phase) {
5132 Node* addr = in(RawAddress);
5133 if (offset != 0) {
5134 Compile* C = phase->C;
5135 addr = phase->transform( new AddPNode(C->top(), addr,
5136 phase->MakeConX(offset)) );
5137 }
5138 return addr;
5139 }
5140
5141 // Clone the given store, converting it into a raw store
5142 // initializing a field or element of my new object.
5143 // Caller is responsible for retiring the original store,
5144 // with subsume_node or the like.
5145 //
5146 // From the example above InitializeNode::InitializeNode,
5147 // here are the old stores to be captured:
5148 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
5149 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
5150 //
5151 // Here is the changed code; note the extra edges on init:
5152 // alloc = (Allocate ...)
5153 // rawoop = alloc.RawAddress
5154 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
5155 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
5156 // init = (Initialize alloc.Control alloc.Memory rawoop
5157 // rawstore1 rawstore2)
5158 //
5159 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
5160 PhaseGVN* phase, bool can_reshape) {
5161 assert(stores_are_sane(phase), "");
5162
5163 if (start < 0) return nullptr;
5164 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
5165
5166 Compile* C = phase->C;
5167 int size_in_bytes = st->memory_size();
5168 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5169 if (i == 0) return nullptr; // bail out
5170 Node* prev_mem = nullptr; // raw memory for the captured store
5171 if (i > 0) {
5172 prev_mem = in(i); // there is a pre-existing store under this one
5173 set_req(i, C->top()); // temporarily disconnect it
5174 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
5175 } else {
5176 i = -i; // no pre-existing store
5177 prev_mem = zero_memory(); // a slice of the newly allocated object
5178 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
5179 set_req(--i, C->top()); // reuse this edge; it has been folded away
5180 else
5181 ins_req(i, C->top()); // build a new edge
5182 }
5183 Node* new_st = st->clone();
5184 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5185 new_st->set_req(MemNode::Control, in(Control));
5186 new_st->set_req(MemNode::Memory, prev_mem);
5187 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
5188 bs->eliminate_gc_barrier_data(new_st);
5189 new_st = phase->transform(new_st);
5190
5191 // At this point, new_st might have swallowed a pre-existing store
5192 // at the same offset, or perhaps new_st might have disappeared,
5193 // if it redundantly stored the same value (or zero to fresh memory).
5194
5195 // In any case, wire it in:
5196 PhaseIterGVN* igvn = phase->is_IterGVN();
5197 if (igvn) {
5198 igvn->rehash_node_delayed(this);
5199 }
5200 set_req(i, new_st);
5201
5202 // The caller may now kill the old guy.
5203 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
5204 assert(check_st == new_st || check_st == nullptr, "must be findable");
5205 assert(!is_complete(), "");
5206 return new_st;
5207 }
5208
5209 static bool store_constant(jlong* tiles, int num_tiles,
5210 intptr_t st_off, int st_size,
5211 jlong con) {
5212 if ((st_off & (st_size-1)) != 0)
5213 return false; // strange store offset (assume size==2**N)
5214 address addr = (address)tiles + st_off;
5215 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5216 switch (st_size) {
5217 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
5218 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
5219 case sizeof(jint): *(jint*) addr = (jint) con; break;
5220 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5221 default: return false; // strange store size (detect size!=2**N here)
5222 }
5223 return true; // return success to caller
5224 }
5225
5226 // Coalesce subword constants into int constants and possibly
5227 // into long constants. The goal, if the CPU permits,
5228 // is to initialize the object with a small number of 64-bit tiles.
5229 // Also, convert floating-point constants to bit patterns.
5230 // Non-constants are not relevant to this pass.
5231 //
5232 // In terms of the running example on InitializeNode::InitializeNode
5233 // and InitializeNode::capture_store, here is the transformation
5234 // of rawstore1 and rawstore2 into rawstore12:
5235 // alloc = (Allocate ...)
5236 // rawoop = alloc.RawAddress
5237 // tile12 = 0x00010002
5238 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5239 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5240 //
5241 void
5242 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5243 Node* size_in_bytes,
5244 PhaseGVN* phase) {
5245 Compile* C = phase->C;
5246
5247 assert(stores_are_sane(phase), "");
5248 // Note: After this pass, they are not completely sane,
5249 // since there may be some overlaps.
5250
5251 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5252
5253 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5254 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5255 size_limit = MIN2(size_limit, ti_limit);
5256 size_limit = align_up(size_limit, BytesPerLong);
5257 int num_tiles = size_limit / BytesPerLong;
5258
5259 // allocate space for the tile map:
5260 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5261 jlong tiles_buf[small_len];
5262 Node* nodes_buf[small_len];
5263 jlong inits_buf[small_len];
5264 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5265 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5266 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5267 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5268 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5269 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5270 // tiles: exact bitwise model of all primitive constants
5271 // nodes: last constant-storing node subsumed into the tiles model
5272 // inits: which bytes (in each tile) are touched by any initializations
5273
5274 //// Pass A: Fill in the tile model with any relevant stores.
5275
5276 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5277 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5278 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5279 Node* zmem = zero_memory(); // initially zero memory state
5280 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5281 Node* st = in(i);
5282 intptr_t st_off = get_store_offset(st, phase);
5283
5284 // Figure out the store's offset and constant value:
5285 if (st_off < header_size) continue; //skip (ignore header)
5286 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5287 int st_size = st->as_Store()->memory_size();
5288 if (st_off + st_size > size_limit) break;
5289
5290 // Record which bytes are touched, whether by constant or not.
5291 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5292 continue; // skip (strange store size)
5293
5294 const Type* val = phase->type(st->in(MemNode::ValueIn));
5295 if (!val->singleton()) continue; //skip (non-con store)
5296 BasicType type = val->basic_type();
5297
5298 jlong con = 0;
5299 switch (type) {
5300 case T_INT: con = val->is_int()->get_con(); break;
5301 case T_LONG: con = val->is_long()->get_con(); break;
5302 case T_FLOAT: con = jint_cast(val->getf()); break;
5303 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5304 default: continue; //skip (odd store type)
5305 }
5306
5307 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5308 st->Opcode() == Op_StoreL) {
5309 continue; // This StoreL is already optimal.
5310 }
5311
5312 // Store down the constant.
5313 store_constant(tiles, num_tiles, st_off, st_size, con);
5314
5315 intptr_t j = st_off >> LogBytesPerLong;
5316
5317 if (type == T_INT && st_size == BytesPerInt
5318 && (st_off & BytesPerInt) == BytesPerInt) {
5319 jlong lcon = tiles[j];
5320 if (!Matcher::isSimpleConstant64(lcon) &&
5321 st->Opcode() == Op_StoreI) {
5322 // This StoreI is already optimal by itself.
5323 jint* intcon = (jint*) &tiles[j];
5324 intcon[1] = 0; // undo the store_constant()
5325
5326 // If the previous store is also optimal by itself, back up and
5327 // undo the action of the previous loop iteration... if we can.
5328 // But if we can't, just let the previous half take care of itself.
5329 st = nodes[j];
5330 st_off -= BytesPerInt;
5331 con = intcon[0];
5332 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5333 assert(st_off >= header_size, "still ignoring header");
5334 assert(get_store_offset(st, phase) == st_off, "must be");
5335 assert(in(i-1) == zmem, "must be");
5336 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5337 assert(con == tcon->is_int()->get_con(), "must be");
5338 // Undo the effects of the previous loop trip, which swallowed st:
5339 intcon[0] = 0; // undo store_constant()
5340 set_req(i-1, st); // undo set_req(i, zmem)
5341 nodes[j] = nullptr; // undo nodes[j] = st
5342 --old_subword; // undo ++old_subword
5343 }
5344 continue; // This StoreI is already optimal.
5345 }
5346 }
5347
5348 // This store is not needed.
5349 set_req(i, zmem);
5350 nodes[j] = st; // record for the moment
5351 if (st_size < BytesPerLong) // something has changed
5352 ++old_subword; // includes int/float, but who's counting...
5353 else ++old_long;
5354 }
5355
5356 if ((old_subword + old_long) == 0)
5357 return; // nothing more to do
5358
5359 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5360 // Be sure to insert them before overlapping non-constant stores.
5361 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5362 for (int j = 0; j < num_tiles; j++) {
5363 jlong con = tiles[j];
5364 jlong init = inits[j];
5365 if (con == 0) continue;
5366 jint con0, con1; // split the constant, address-wise
5367 jint init0, init1; // split the init map, address-wise
5368 { union { jlong con; jint intcon[2]; } u;
5369 u.con = con;
5370 con0 = u.intcon[0];
5371 con1 = u.intcon[1];
5372 u.con = init;
5373 init0 = u.intcon[0];
5374 init1 = u.intcon[1];
5375 }
5376
5377 Node* old = nodes[j];
5378 assert(old != nullptr, "need the prior store");
5379 intptr_t offset = (j * BytesPerLong);
5380
5381 bool split = !Matcher::isSimpleConstant64(con);
5382
5383 if (offset < header_size) {
5384 assert(offset + BytesPerInt >= header_size, "second int counts");
5385 assert(*(jint*)&tiles[j] == 0, "junk in header");
5386 split = true; // only the second word counts
5387 // Example: int a[] = { 42 ... }
5388 } else if (con0 == 0 && init0 == -1) {
5389 split = true; // first word is covered by full inits
5390 // Example: int a[] = { ... foo(), 42 ... }
5391 } else if (con1 == 0 && init1 == -1) {
5392 split = true; // second word is covered by full inits
5393 // Example: int a[] = { ... 42, foo() ... }
5394 }
5395
5396 // Here's a case where init0 is neither 0 nor -1:
5397 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5398 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5399 // In this case the tile is not split; it is (jlong)42.
5400 // The big tile is stored down, and then the foo() value is inserted.
5401 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5402
5403 Node* ctl = old->in(MemNode::Control);
5404 Node* adr = make_raw_address(offset, phase);
5405 const TypePtr* atp = TypeRawPtr::BOTTOM;
5406
5407 // One or two coalesced stores to plop down.
5408 Node* st[2];
5409 intptr_t off[2];
5410 int nst = 0;
5411 if (!split) {
5412 ++new_long;
5413 off[nst] = offset;
5414 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5415 phase->longcon(con), T_LONG, MemNode::unordered);
5416 } else {
5417 // Omit either if it is a zero.
5418 if (con0 != 0) {
5419 ++new_int;
5420 off[nst] = offset;
5421 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5422 phase->intcon(con0), T_INT, MemNode::unordered);
5423 }
5424 if (con1 != 0) {
5425 ++new_int;
5426 offset += BytesPerInt;
5427 adr = make_raw_address(offset, phase);
5428 off[nst] = offset;
5429 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5430 phase->intcon(con1), T_INT, MemNode::unordered);
5431 }
5432 }
5433
5434 // Insert second store first, then the first before the second.
5435 // Insert each one just before any overlapping non-constant stores.
5436 while (nst > 0) {
5437 Node* st1 = st[--nst];
5438 C->copy_node_notes_to(st1, old);
5439 st1 = phase->transform(st1);
5440 offset = off[nst];
5441 assert(offset >= header_size, "do not smash header");
5442 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5443 guarantee(ins_idx != 0, "must re-insert constant store");
5444 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5445 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5446 set_req(--ins_idx, st1);
5447 else
5448 ins_req(ins_idx, st1);
5449 }
5450 }
5451
5452 if (PrintCompilation && WizardMode)
5453 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5454 old_subword, old_long, new_int, new_long);
5455 if (C->log() != nullptr)
5456 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5457 old_subword, old_long, new_int, new_long);
5458
5459 // Clean up any remaining occurrences of zmem:
5460 remove_extra_zeroes();
5461 }
5462
5463 // Explore forward from in(start) to find the first fully initialized
5464 // word, and return its offset. Skip groups of subword stores which
5465 // together initialize full words. If in(start) is itself part of a
5466 // fully initialized word, return the offset of in(start). If there
5467 // are no following full-word stores, or if something is fishy, return
5468 // a negative value.
5469 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5470 int int_map = 0;
5471 intptr_t int_map_off = 0;
5472 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5473
5474 for (uint i = start, limit = req(); i < limit; i++) {
5475 Node* st = in(i);
5476
5477 intptr_t st_off = get_store_offset(st, phase);
5478 if (st_off < 0) break; // return conservative answer
5479
5480 int st_size = st->as_Store()->memory_size();
5481 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5482 return st_off; // we found a complete word init
5483 }
5484
5485 // update the map:
5486
5487 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5488 if (this_int_off != int_map_off) {
5489 // reset the map:
5490 int_map = 0;
5491 int_map_off = this_int_off;
5492 }
5493
5494 int subword_off = st_off - this_int_off;
5495 int_map |= right_n_bits(st_size) << subword_off;
5496 if ((int_map & FULL_MAP) == FULL_MAP) {
5497 return this_int_off; // we found a complete word init
5498 }
5499
5500 // Did this store hit or cross the word boundary?
5501 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5502 if (next_int_off == this_int_off + BytesPerInt) {
5503 // We passed the current int, without fully initializing it.
5504 int_map_off = next_int_off;
5505 int_map >>= BytesPerInt;
5506 } else if (next_int_off > this_int_off + BytesPerInt) {
5507 // We passed the current and next int.
5508 return this_int_off + BytesPerInt;
5509 }
5510 }
5511
5512 return -1;
5513 }
5514
5515
5516 // Called when the associated AllocateNode is expanded into CFG.
5517 // At this point, we may perform additional optimizations.
5518 // Linearize the stores by ascending offset, to make memory
5519 // activity as coherent as possible.
5520 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5521 intptr_t header_size,
5522 Node* size_in_bytes,
5523 PhaseIterGVN* phase) {
5524 assert(!is_complete(), "not already complete");
5525 assert(stores_are_sane(phase), "");
5526 assert(allocation() != nullptr, "must be present");
5527
5528 remove_extra_zeroes();
5529
5530 if (ReduceFieldZeroing || ReduceBulkZeroing)
5531 // reduce instruction count for common initialization patterns
5532 coalesce_subword_stores(header_size, size_in_bytes, phase);
5533
5534 Node* zmem = zero_memory(); // initially zero memory state
5535 Node* inits = zmem; // accumulating a linearized chain of inits
5536 #ifdef ASSERT
5537 intptr_t first_offset = allocation()->minimum_header_size();
5538 intptr_t last_init_off = first_offset; // previous init offset
5539 intptr_t last_init_end = first_offset; // previous init offset+size
5540 intptr_t last_tile_end = first_offset; // previous tile offset+size
5541 #endif
5542 intptr_t zeroes_done = header_size;
5543
5544 bool do_zeroing = true; // we might give up if inits are very sparse
5545 int big_init_gaps = 0; // how many large gaps have we seen?
5546
5547 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5548 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5549
5550 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5551 Node* st = in(i);
5552 intptr_t st_off = get_store_offset(st, phase);
5553 if (st_off < 0)
5554 break; // unknown junk in the inits
5555 if (st->in(MemNode::Memory) != zmem)
5556 break; // complicated store chains somehow in list
5557
5558 int st_size = st->as_Store()->memory_size();
5559 intptr_t next_init_off = st_off + st_size;
5560
5561 if (do_zeroing && zeroes_done < next_init_off) {
5562 // See if this store needs a zero before it or under it.
5563 intptr_t zeroes_needed = st_off;
5564
5565 if (st_size < BytesPerInt) {
5566 // Look for subword stores which only partially initialize words.
5567 // If we find some, we must lay down some word-level zeroes first,
5568 // underneath the subword stores.
5569 //
5570 // Examples:
5571 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5572 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5573 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5574 //
5575 // Note: coalesce_subword_stores may have already done this,
5576 // if it was prompted by constant non-zero subword initializers.
5577 // But this case can still arise with non-constant stores.
5578
5579 intptr_t next_full_store = find_next_fullword_store(i, phase);
5580
5581 // In the examples above:
5582 // in(i) p q r s x y z
5583 // st_off 12 13 14 15 12 13 14
5584 // st_size 1 1 1 1 1 1 1
5585 // next_full_s. 12 16 16 16 16 16 16
5586 // z's_done 12 16 16 16 12 16 12
5587 // z's_needed 12 16 16 16 16 16 16
5588 // zsize 0 0 0 0 4 0 4
5589 if (next_full_store < 0) {
5590 // Conservative tack: Zero to end of current word.
5591 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5592 } else {
5593 // Zero to beginning of next fully initialized word.
5594 // Or, don't zero at all, if we are already in that word.
5595 assert(next_full_store >= zeroes_needed, "must go forward");
5596 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5597 zeroes_needed = next_full_store;
5598 }
5599 }
5600
5601 if (zeroes_needed > zeroes_done) {
5602 intptr_t zsize = zeroes_needed - zeroes_done;
5603 // Do some incremental zeroing on rawmem, in parallel with inits.
5604 zeroes_done = align_down(zeroes_done, BytesPerInt);
5605 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5606 allocation()->in(AllocateNode::InitValue),
5607 allocation()->in(AllocateNode::RawInitValue),
5608 zeroes_done, zeroes_needed,
5609 phase);
5610 zeroes_done = zeroes_needed;
5611 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5612 do_zeroing = false; // leave the hole, next time
5613 }
5614 }
5615
5616 // Collect the store and move on:
5617 phase->replace_input_of(st, MemNode::Memory, inits);
5618 inits = st; // put it on the linearized chain
5619 set_req(i, zmem); // unhook from previous position
5620
5621 if (zeroes_done == st_off)
5622 zeroes_done = next_init_off;
5623
5624 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5625
5626 #ifdef ASSERT
5627 // Various order invariants. Weaker than stores_are_sane because
5628 // a large constant tile can be filled in by smaller non-constant stores.
5629 assert(st_off >= last_init_off, "inits do not reverse");
5630 last_init_off = st_off;
5631 const Type* val = nullptr;
5632 if (st_size >= BytesPerInt &&
5633 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5634 (int)val->basic_type() < (int)T_OBJECT) {
5635 assert(st_off >= last_tile_end, "tiles do not overlap");
5636 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5637 last_tile_end = MAX2(last_tile_end, next_init_off);
5638 } else {
5639 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5640 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5641 assert(st_off >= last_init_end, "inits do not overlap");
5642 last_init_end = next_init_off; // it's a non-tile
5643 }
5644 #endif //ASSERT
5645 }
5646
5647 remove_extra_zeroes(); // clear out all the zmems left over
5648 add_req(inits);
5649
5650 if (!(UseTLAB && ZeroTLAB)) {
5651 // If anything remains to be zeroed, zero it all now.
5652 zeroes_done = align_down(zeroes_done, BytesPerInt);
5653 // if it is the last unused 4 bytes of an instance, forget about it
5654 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5655 if (zeroes_done + BytesPerLong >= size_limit) {
5656 AllocateNode* alloc = allocation();
5657 assert(alloc != nullptr, "must be present");
5658 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5659 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5660 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5661 if (zeroes_done == k->layout_helper())
5662 zeroes_done = size_limit;
5663 }
5664 }
5665 if (zeroes_done < size_limit) {
5666 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5667 allocation()->in(AllocateNode::InitValue),
5668 allocation()->in(AllocateNode::RawInitValue),
5669 zeroes_done, size_in_bytes, phase);
5670 }
5671 }
5672
5673 set_complete(phase);
5674 return rawmem;
5675 }
5676
5677
5678 #ifdef ASSERT
5679 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5680 if (is_complete())
5681 return true; // stores could be anything at this point
5682 assert(allocation() != nullptr, "must be present");
5683 intptr_t last_off = allocation()->minimum_header_size();
5684 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5685 Node* st = in(i);
5686 intptr_t st_off = get_store_offset(st, phase);
5687 if (st_off < 0) continue; // ignore dead garbage
5688 if (last_off > st_off) {
5689 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5690 this->dump(2);
5691 assert(false, "ascending store offsets");
5692 return false;
5693 }
5694 last_off = st_off + st->as_Store()->memory_size();
5695 }
5696 return true;
5697 }
5698 #endif //ASSERT
5699
5700
5701
5702
5703 //============================MergeMemNode=====================================
5704 //
5705 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5706 // contributing store or call operations. Each contributor provides the memory
5707 // state for a particular "alias type" (see Compile::alias_type). For example,
5708 // if a MergeMem has an input X for alias category #6, then any memory reference
5709 // to alias category #6 may use X as its memory state input, as an exact equivalent
5710 // to using the MergeMem as a whole.
5711 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5712 //
5713 // (Here, the <N> notation gives the index of the relevant adr_type.)
5714 //
5715 // In one special case (and more cases in the future), alias categories overlap.
5716 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5717 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5718 // it is exactly equivalent to that state W:
5719 // MergeMem(<Bot>: W) <==> W
5720 //
5721 // Usually, the merge has more than one input. In that case, where inputs
5722 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5723 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5724 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5725 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5726 //
5727 // A merge can take a "wide" memory state as one of its narrow inputs.
5728 // This simply means that the merge observes out only the relevant parts of
5729 // the wide input. That is, wide memory states arriving at narrow merge inputs
5730 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
5731 //
5732 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5733 // and that memory slices "leak through":
5734 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5735 //
5736 // But, in such a cascade, repeated memory slices can "block the leak":
5737 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5738 //
5739 // In the last example, Y is not part of the combined memory state of the
5740 // outermost MergeMem. The system must, of course, prevent unschedulable
5741 // memory states from arising, so you can be sure that the state Y is somehow
5742 // a precursor to state Y'.
5743 //
5744 //
5745 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5746 // of each MergeMemNode array are exactly the numerical alias indexes, including
5747 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
5748 // Compile::alias_type (and kin) produce and manage these indexes.
5749 //
5750 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5751 // (Note that this provides quick access to the top node inside MergeMem methods,
5752 // without the need to reach out via TLS to Compile::current.)
5753 //
5754 // As a consequence of what was just described, a MergeMem that represents a full
5755 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5756 // containing all alias categories.
5757 //
5758 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5759 //
5760 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5761 // a memory state for the alias type <N>, or else the top node, meaning that
5762 // there is no particular input for that alias type. Note that the length of
5763 // a MergeMem is variable, and may be extended at any time to accommodate new
5764 // memory states at larger alias indexes. When merges grow, they are of course
5765 // filled with "top" in the unused in() positions.
5766 //
5767 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5768 // (Top was chosen because it works smoothly with passes like GCM.)
5769 //
5770 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
5771 // the type of random VM bits like TLS references.) Since it is always the
5772 // first non-Bot memory slice, some low-level loops use it to initialize an
5773 // index variable: for (i = AliasIdxRaw; i < req(); i++).
5774 //
5775 //
5776 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
5777 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
5778 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5779 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
5780 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
5781 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5782 //
5783 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5784 // really that different from the other memory inputs. An abbreviation called
5785 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5786 //
5787 //
5788 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
5789 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
5790 // that "emerges though" the base memory will be marked as excluding the alias types
5791 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5792 //
5793 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5794 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5795 //
5796 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5797 // (It is currently unimplemented.) As you can see, the resulting merge is
5798 // actually a disjoint union of memory states, rather than an overlay.
5799 //
5800
5801 //------------------------------MergeMemNode-----------------------------------
5802 Node* MergeMemNode::make_empty_memory() {
5803 Node* empty_memory = (Node*) Compile::current()->top();
5804 assert(empty_memory->is_top(), "correct sentinel identity");
5805 return empty_memory;
5806 }
5807
5808 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5809 init_class_id(Class_MergeMem);
5810 // all inputs are nullified in Node::Node(int)
5811 // set_input(0, nullptr); // no control input
5812
5813 // Initialize the edges uniformly to top, for starters.
5814 Node* empty_mem = make_empty_memory();
5815 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5816 init_req(i,empty_mem);
5817 }
5818 assert(empty_memory() == empty_mem, "");
5819
5820 if( new_base != nullptr && new_base->is_MergeMem() ) {
5821 MergeMemNode* mdef = new_base->as_MergeMem();
5822 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5823 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5824 mms.set_memory(mms.memory2());
5825 }
5826 assert(base_memory() == mdef->base_memory(), "");
5827 } else {
5828 set_base_memory(new_base);
5829 }
5830 }
5831
5832 // Make a new, untransformed MergeMem with the same base as 'mem'.
5833 // If mem is itself a MergeMem, populate the result with the same edges.
5834 MergeMemNode* MergeMemNode::make(Node* mem) {
5835 return new MergeMemNode(mem);
5836 }
5837
5838 //------------------------------cmp--------------------------------------------
5839 uint MergeMemNode::hash() const { return NO_HASH; }
5840 bool MergeMemNode::cmp( const Node &n ) const {
5841 return (&n == this); // Always fail except on self
5842 }
5843
5844 //------------------------------Identity---------------------------------------
5845 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5846 // Identity if this merge point does not record any interesting memory
5847 // disambiguations.
5848 Node* base_mem = base_memory();
5849 Node* empty_mem = empty_memory();
5850 if (base_mem != empty_mem) { // Memory path is not dead?
5851 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5852 Node* mem = in(i);
5853 if (mem != empty_mem && mem != base_mem) {
5854 return this; // Many memory splits; no change
5855 }
5856 }
5857 }
5858 return base_mem; // No memory splits; ID on the one true input
5859 }
5860
5861 //------------------------------Ideal------------------------------------------
5862 // This method is invoked recursively on chains of MergeMem nodes
5863 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5864 // Remove chain'd MergeMems
5865 //
5866 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5867 // relative to the "in(Bot)". Since we are patching both at the same time,
5868 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5869 // but rewrite each "in(i)" relative to the new "in(Bot)".
5870 Node *progress = nullptr;
5871
5872
5873 Node* old_base = base_memory();
5874 Node* empty_mem = empty_memory();
5875 if (old_base == empty_mem)
5876 return nullptr; // Dead memory path.
5877
5878 MergeMemNode* old_mbase;
5879 if (old_base != nullptr && old_base->is_MergeMem())
5880 old_mbase = old_base->as_MergeMem();
5881 else
5882 old_mbase = nullptr;
5883 Node* new_base = old_base;
5884
5885 // simplify stacked MergeMems in base memory
5886 if (old_mbase) new_base = old_mbase->base_memory();
5887
5888 // the base memory might contribute new slices beyond my req()
5889 if (old_mbase) grow_to_match(old_mbase);
5890
5891 // Note: We do not call verify_sparse on entry, because inputs
5892 // can normalize to the base_memory via subsume_node or similar
5893 // mechanisms. This method repairs that damage.
5894
5895 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5896
5897 // Look at each slice.
5898 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5899 Node* old_in = in(i);
5900 // calculate the old memory value
5901 Node* old_mem = old_in;
5902 if (old_mem == empty_mem) old_mem = old_base;
5903 assert(old_mem == memory_at(i), "");
5904
5905 // maybe update (reslice) the old memory value
5906
5907 // simplify stacked MergeMems
5908 Node* new_mem = old_mem;
5909 MergeMemNode* old_mmem;
5910 if (old_mem != nullptr && old_mem->is_MergeMem())
5911 old_mmem = old_mem->as_MergeMem();
5912 else
5913 old_mmem = nullptr;
5914 if (old_mmem == this) {
5915 // This can happen if loops break up and safepoints disappear.
5916 // A merge of BotPtr (default) with a RawPtr memory derived from a
5917 // safepoint can be rewritten to a merge of the same BotPtr with
5918 // the BotPtr phi coming into the loop. If that phi disappears
5919 // also, we can end up with a self-loop of the mergemem.
5920 // In general, if loops degenerate and memory effects disappear,
5921 // a mergemem can be left looking at itself. This simply means
5922 // that the mergemem's default should be used, since there is
5923 // no longer any apparent effect on this slice.
5924 // Note: If a memory slice is a MergeMem cycle, it is unreachable
5925 // from start. Update the input to TOP.
5926 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5927 }
5928 else if (old_mmem != nullptr) {
5929 new_mem = old_mmem->memory_at(i);
5930 }
5931 // else preceding memory was not a MergeMem
5932
5933 // maybe store down a new value
5934 Node* new_in = new_mem;
5935 if (new_in == new_base) new_in = empty_mem;
5936
5937 if (new_in != old_in) {
5938 // Warning: Do not combine this "if" with the previous "if"
5939 // A memory slice might have be be rewritten even if it is semantically
5940 // unchanged, if the base_memory value has changed.
5941 set_req_X(i, new_in, phase);
5942 progress = this; // Report progress
5943 }
5944 }
5945
5946 if (new_base != old_base) {
5947 set_req_X(Compile::AliasIdxBot, new_base, phase);
5948 // Don't use set_base_memory(new_base), because we need to update du.
5949 assert(base_memory() == new_base, "");
5950 progress = this;
5951 }
5952
5953 if( base_memory() == this ) {
5954 // a self cycle indicates this memory path is dead
5955 set_req(Compile::AliasIdxBot, empty_mem);
5956 }
5957
5958 // Resolve external cycles by calling Ideal on a MergeMem base_memory
5959 // Recursion must occur after the self cycle check above
5960 if( base_memory()->is_MergeMem() ) {
5961 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5962 Node *m = phase->transform(new_mbase); // Rollup any cycles
5963 if( m != nullptr &&
5964 (m->is_top() ||
5965 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5966 // propagate rollup of dead cycle to self
5967 set_req(Compile::AliasIdxBot, empty_mem);
5968 }
5969 }
5970
5971 if( base_memory() == empty_mem ) {
5972 progress = this;
5973 // Cut inputs during Parse phase only.
5974 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5975 if( !can_reshape ) {
5976 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5977 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5978 }
5979 }
5980 }
5981
5982 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5983 // Check if PhiNode::Ideal's "Split phis through memory merges"
5984 // transform should be attempted. Look for this->phi->this cycle.
5985 uint merge_width = req();
5986 if (merge_width > Compile::AliasIdxRaw) {
5987 PhiNode* phi = base_memory()->as_Phi();
5988 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5989 if (phi->in(i) == this) {
5990 phase->is_IterGVN()->_worklist.push(phi);
5991 break;
5992 }
5993 }
5994 }
5995 }
5996
5997 assert(progress || verify_sparse(), "please, no dups of base");
5998 return progress;
5999 }
6000
6001 //-------------------------set_base_memory-------------------------------------
6002 void MergeMemNode::set_base_memory(Node *new_base) {
6003 Node* empty_mem = empty_memory();
6004 set_req(Compile::AliasIdxBot, new_base);
6005 assert(memory_at(req()) == new_base, "must set default memory");
6006 // Clear out other occurrences of new_base:
6007 if (new_base != empty_mem) {
6008 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6009 if (in(i) == new_base) set_req(i, empty_mem);
6010 }
6011 }
6012 }
6013
6014 //------------------------------out_RegMask------------------------------------
6015 const RegMask &MergeMemNode::out_RegMask() const {
6016 return RegMask::Empty;
6017 }
6018
6019 //------------------------------dump_spec--------------------------------------
6020 #ifndef PRODUCT
6021 void MergeMemNode::dump_spec(outputStream *st) const {
6022 st->print(" {");
6023 Node* base_mem = base_memory();
6024 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
6025 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
6026 if (mem == base_mem) { st->print(" -"); continue; }
6027 st->print( " N%d:", mem->_idx );
6028 Compile::current()->get_adr_type(i)->dump_on(st);
6029 }
6030 st->print(" }");
6031 }
6032 #endif // !PRODUCT
6033
6034
6035 #ifdef ASSERT
6036 static bool might_be_same(Node* a, Node* b) {
6037 if (a == b) return true;
6038 if (!(a->is_Phi() || b->is_Phi())) return false;
6039 // phis shift around during optimization
6040 return true; // pretty stupid...
6041 }
6042
6043 // verify a narrow slice (either incoming or outgoing)
6044 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
6045 if (!VerifyAliases) return; // don't bother to verify unless requested
6046 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
6047 if (Node::in_dump()) return; // muzzle asserts when printing
6048 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
6049 assert(n != nullptr, "");
6050 // Elide intervening MergeMem's
6051 while (n->is_MergeMem()) {
6052 n = n->as_MergeMem()->memory_at(alias_idx);
6053 }
6054 Compile* C = Compile::current();
6055 const TypePtr* n_adr_type = n->adr_type();
6056 if (n == m->empty_memory()) {
6057 // Implicit copy of base_memory()
6058 } else if (n_adr_type != TypePtr::BOTTOM) {
6059 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
6060 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
6061 } else {
6062 // A few places like make_runtime_call "know" that VM calls are narrow,
6063 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
6064 bool expected_wide_mem = false;
6065 if (n == m->base_memory()) {
6066 expected_wide_mem = true;
6067 } else if (alias_idx == Compile::AliasIdxRaw ||
6068 n == m->memory_at(Compile::AliasIdxRaw)) {
6069 expected_wide_mem = true;
6070 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
6071 // memory can "leak through" calls on channels that
6072 // are write-once. Allow this also.
6073 expected_wide_mem = true;
6074 }
6075 assert(expected_wide_mem, "expected narrow slice replacement");
6076 }
6077 }
6078 #else // !ASSERT
6079 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
6080 #endif
6081
6082
6083 //-----------------------------memory_at---------------------------------------
6084 Node* MergeMemNode::memory_at(uint alias_idx) const {
6085 assert(alias_idx >= Compile::AliasIdxRaw ||
6086 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
6087 "must avoid base_memory and AliasIdxTop");
6088
6089 // Otherwise, it is a narrow slice.
6090 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
6091 if (is_empty_memory(n)) {
6092 // the array is sparse; empty slots are the "top" node
6093 n = base_memory();
6094 assert(Node::in_dump()
6095 || n == nullptr || n->bottom_type() == Type::TOP
6096 || n->adr_type() == nullptr // address is TOP
6097 || n->adr_type() == TypePtr::BOTTOM
6098 || n->adr_type() == TypeRawPtr::BOTTOM
6099 || !Compile::current()->do_aliasing(),
6100 "must be a wide memory");
6101 // do_aliasing == false if we are organizing the memory states manually.
6102 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
6103 } else {
6104 // make sure the stored slice is sane
6105 #ifdef ASSERT
6106 if (VMError::is_error_reported() || Node::in_dump()) {
6107 } else if (might_be_same(n, base_memory())) {
6108 // Give it a pass: It is a mostly harmless repetition of the base.
6109 // This can arise normally from node subsumption during optimization.
6110 } else {
6111 verify_memory_slice(this, alias_idx, n);
6112 }
6113 #endif
6114 }
6115 return n;
6116 }
6117
6118 //---------------------------set_memory_at-------------------------------------
6119 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
6120 verify_memory_slice(this, alias_idx, n);
6121 Node* empty_mem = empty_memory();
6122 if (n == base_memory()) n = empty_mem; // collapse default
6123 uint need_req = alias_idx+1;
6124 if (req() < need_req) {
6125 if (n == empty_mem) return; // already the default, so do not grow me
6126 // grow the sparse array
6127 do {
6128 add_req(empty_mem);
6129 } while (req() < need_req);
6130 }
6131 set_req( alias_idx, n );
6132 }
6133
6134
6135
6136 //--------------------------iteration_setup------------------------------------
6137 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
6138 if (other != nullptr) {
6139 grow_to_match(other);
6140 // invariant: the finite support of mm2 is within mm->req()
6141 #ifdef ASSERT
6142 for (uint i = req(); i < other->req(); i++) {
6143 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
6144 }
6145 #endif
6146 }
6147 // Replace spurious copies of base_memory by top.
6148 Node* base_mem = base_memory();
6149 if (base_mem != nullptr && !base_mem->is_top()) {
6150 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
6151 if (in(i) == base_mem)
6152 set_req(i, empty_memory());
6153 }
6154 }
6155 }
6156
6157 //---------------------------grow_to_match-------------------------------------
6158 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
6159 Node* empty_mem = empty_memory();
6160 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
6161 // look for the finite support of the other memory
6162 for (uint i = other->req(); --i >= req(); ) {
6163 if (other->in(i) != empty_mem) {
6164 uint new_len = i+1;
6165 while (req() < new_len) add_req(empty_mem);
6166 break;
6167 }
6168 }
6169 }
6170
6171 //---------------------------verify_sparse-------------------------------------
6172 #ifndef PRODUCT
6173 bool MergeMemNode::verify_sparse() const {
6174 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
6175 Node* base_mem = base_memory();
6176 // The following can happen in degenerate cases, since empty==top.
6177 if (is_empty_memory(base_mem)) return true;
6178 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6179 assert(in(i) != nullptr, "sane slice");
6180 if (in(i) == base_mem) return false; // should have been the sentinel value!
6181 }
6182 return true;
6183 }
6184
6185 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
6186 Node* n;
6187 n = mm->in(idx);
6188 if (mem == n) return true; // might be empty_memory()
6189 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
6190 if (mem == n) return true;
6191 return false;
6192 }
6193 #endif // !PRODUCT