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