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