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