1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciFlatArrayKlass.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "compiler/compileLog.hpp"
30 #include "gc/shared/barrierSet.hpp"
31 #include "gc/shared/c2/barrierSetC2.hpp"
32 #include "gc/shared/tlab_globals.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "oops/objArrayKlass.hpp"
36 #include "opto/addnode.hpp"
37 #include "opto/arraycopynode.hpp"
38 #include "opto/cfgnode.hpp"
39 #include "opto/regalloc.hpp"
40 #include "opto/compile.hpp"
41 #include "opto/connode.hpp"
42 #include "opto/convertnode.hpp"
43 #include "opto/inlinetypenode.hpp"
44 #include "opto/loopnode.hpp"
45 #include "opto/machnode.hpp"
46 #include "opto/matcher.hpp"
47 #include "opto/memnode.hpp"
48 #include "opto/mulnode.hpp"
49 #include "opto/narrowptrnode.hpp"
50 #include "opto/phaseX.hpp"
51 #include "opto/regmask.hpp"
52 #include "opto/rootnode.hpp"
53 #include "opto/vectornode.hpp"
54 #include "utilities/align.hpp"
55 #include "utilities/copy.hpp"
56 #include "utilities/macros.hpp"
57 #include "utilities/powerOfTwo.hpp"
58 #include "utilities/vmError.hpp"
59
60 // Portions of code courtesy of Clifford Click
61
62 // Optimization - Graph Style
63
64 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
65
66 //=============================================================================
67 uint MemNode::size_of() const { return sizeof(*this); }
68
69 const TypePtr *MemNode::adr_type() const {
70 Node* adr = in(Address);
71 if (adr == nullptr) return nullptr; // node is dead
72 const TypePtr* cross_check = nullptr;
73 DEBUG_ONLY(cross_check = _adr_type);
74 return calculate_adr_type(adr->bottom_type(), cross_check);
75 }
76
77 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
78 if (adr != nullptr) {
79 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
80 return true;
81 }
82 }
83 return false;
84 }
85
86 #ifndef PRODUCT
87 void MemNode::dump_spec(outputStream *st) const {
88 if (in(Address) == nullptr) return; // node is dead
89 #ifndef ASSERT
90 // fake the missing field
91 const TypePtr* _adr_type = nullptr;
92 if (in(Address) != nullptr)
93 _adr_type = in(Address)->bottom_type()->isa_ptr();
94 #endif
95 dump_adr_type(this, _adr_type, st);
96
97 Compile* C = Compile::current();
98 if (C->alias_type(_adr_type)->is_volatile()) {
99 st->print(" Volatile!");
100 }
101 if (_unaligned_access) {
102 st->print(" unaligned");
103 }
104 if (_mismatched_access) {
105 st->print(" mismatched");
106 }
107 if (_unsafe_access) {
108 st->print(" unsafe");
109 }
110 }
111
112 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
113 st->print(" @");
114 if (adr_type == nullptr) {
115 st->print("null");
116 } else {
117 adr_type->dump_on(st);
118 Compile* C = Compile::current();
119 Compile::AliasType* atp = nullptr;
120 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
121 if (atp == nullptr)
122 st->print(", idx=?\?;");
123 else if (atp->index() == Compile::AliasIdxBot)
124 st->print(", idx=Bot;");
125 else if (atp->index() == Compile::AliasIdxTop)
126 st->print(", idx=Top;");
127 else if (atp->index() == Compile::AliasIdxRaw)
128 st->print(", idx=Raw;");
129 else {
130 ciField* field = atp->field();
131 if (field) {
132 st->print(", name=");
133 field->print_name_on(st);
134 }
135 st->print(", idx=%d;", atp->index());
136 }
137 }
138 }
139
140 extern void print_alias_types();
141
142 #endif
143
144 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
145 assert((t_oop != nullptr), "sanity");
146 bool is_instance = t_oop->is_known_instance_field();
147 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
148 (load != nullptr) && load->is_Load() &&
149 (phase->is_IterGVN() != nullptr);
150 if (!(is_instance || is_boxed_value_load))
151 return mchain; // don't try to optimize non-instance types
152 uint instance_id = t_oop->instance_id();
153 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
154 Node *prev = nullptr;
155 Node *result = mchain;
156 while (prev != result) {
157 prev = result;
158 if (result == start_mem)
159 break; // hit one of our sentinels
160 // skip over a call which does not affect this memory slice
161 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
162 Node *proj_in = result->in(0);
163 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
164 break; // hit one of our sentinels
165 } else if (proj_in->is_Call()) {
166 // ArrayCopyNodes processed here as well
167 CallNode *call = proj_in->as_Call();
168 if (!call->may_modify(t_oop, phase)) { // returns false for instances
169 result = call->in(TypeFunc::Memory);
170 }
171 } else if (proj_in->is_Initialize()) {
172 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
173 // Stop if this is the initialization for the object instance which
174 // contains this memory slice, otherwise skip over it.
175 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
176 break;
177 }
178 if (is_instance) {
179 result = proj_in->in(TypeFunc::Memory);
180 } else if (is_boxed_value_load) {
181 Node* klass = alloc->in(AllocateNode::KlassNode);
182 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
183 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
184 result = proj_in->in(TypeFunc::Memory); // not related allocation
185 }
186 }
187 } else if (proj_in->is_MemBar()) {
188 ArrayCopyNode* ac = nullptr;
189 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
190 break;
191 }
192 result = proj_in->in(TypeFunc::Memory);
193 } else if (proj_in->is_top()) {
194 break; // dead code
195 } else {
196 assert(false, "unexpected projection");
197 }
198 } else if (result->is_ClearArray()) {
199 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
200 // Can not bypass initialization of the instance
201 // we are looking for.
202 break;
203 }
204 // Otherwise skip it (the call updated 'result' value).
205 } else if (result->is_MergeMem()) {
206 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
207 }
208 }
209 return result;
210 }
211
212 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
213 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
214 if (t_oop == nullptr)
215 return mchain; // don't try to optimize non-oop types
216 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
217 bool is_instance = t_oop->is_known_instance_field();
218 PhaseIterGVN *igvn = phase->is_IterGVN();
219 if (is_instance && igvn != nullptr && result->is_Phi()) {
220 PhiNode *mphi = result->as_Phi();
221 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
222 const TypePtr *t = mphi->adr_type();
223 bool do_split = false;
224 // In the following cases, Load memory input can be further optimized based on
225 // its precise address type
226 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
227 do_split = true;
228 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
229 const TypeOopPtr* mem_t =
230 t->is_oopptr()->cast_to_exactness(true)
231 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
232 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
233 if (t_oop->is_aryptr()) {
234 mem_t = mem_t->is_aryptr()
235 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
236 ->cast_to_size(t_oop->is_aryptr()->size())
237 ->cast_to_not_flat(t_oop->is_aryptr()->is_not_flat())
238 ->cast_to_not_null_free(t_oop->is_aryptr()->is_not_null_free())
239 ->with_offset(t_oop->is_aryptr()->offset())
240 ->is_aryptr();
241 }
242 do_split = mem_t == t_oop;
243 }
244 if (do_split) {
245 // clone the Phi with our address type
246 result = mphi->split_out_instance(t_adr, igvn);
247 } else {
248 // TODO 8325106
249 // assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
250 }
251 }
252 return result;
253 }
254
255 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
256 uint alias_idx = phase->C->get_alias_index(tp);
257 Node *mem = mmem;
258 #ifdef ASSERT
259 {
260 // Check that current type is consistent with the alias index used during graph construction
261 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
262 bool consistent = adr_check == nullptr || adr_check->empty() ||
263 phase->C->must_alias(adr_check, alias_idx );
264 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
265 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
266 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
267 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
268 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
269 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
270 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
271 // don't assert if it is dead code.
272 consistent = true;
273 }
274 if( !consistent ) {
275 st->print("alias_idx==%d, adr_check==", alias_idx);
276 if( adr_check == nullptr ) {
277 st->print("null");
278 } else {
279 adr_check->dump();
280 }
281 st->cr();
282 print_alias_types();
283 assert(consistent, "adr_check must match alias idx");
284 }
285 }
286 #endif
287 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
288 // means an array I have not precisely typed yet. Do not do any
289 // alias stuff with it any time soon.
290 const TypeOopPtr *toop = tp->isa_oopptr();
291 if (tp->base() != Type::AnyPtr &&
292 !(toop &&
293 toop->isa_instptr() &&
294 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
295 toop->offset() == Type::OffsetBot)) {
296 // compress paths and change unreachable cycles to TOP
297 // If not, we can update the input infinitely along a MergeMem cycle
298 // Equivalent code in PhiNode::Ideal
299 Node* m = phase->transform(mmem);
300 // If transformed to a MergeMem, get the desired slice
301 // Otherwise the returned node represents memory for every slice
302 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
303 // Update input if it is progress over what we have now
304 }
305 return mem;
306 }
307
308 //--------------------------Ideal_common---------------------------------------
309 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
310 // Unhook non-raw memories from complete (macro-expanded) initializations.
311 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
312 // If our control input is a dead region, kill all below the region
313 Node *ctl = in(MemNode::Control);
314 if (ctl && remove_dead_region(phase, can_reshape))
315 return this;
316 ctl = in(MemNode::Control);
317 // Don't bother trying to transform a dead node
318 if (ctl && ctl->is_top()) return NodeSentinel;
319
320 PhaseIterGVN *igvn = phase->is_IterGVN();
321 // Wait if control on the worklist.
322 if (ctl && can_reshape && igvn != nullptr) {
323 Node* bol = nullptr;
324 Node* cmp = nullptr;
325 if (ctl->in(0)->is_If()) {
326 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
327 bol = ctl->in(0)->in(1);
328 if (bol->is_Bool())
329 cmp = ctl->in(0)->in(1)->in(1);
330 }
331 if (igvn->_worklist.member(ctl) ||
332 (bol != nullptr && igvn->_worklist.member(bol)) ||
333 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
334 // This control path may be dead.
335 // Delay this memory node transformation until the control is processed.
336 igvn->_worklist.push(this);
337 return NodeSentinel; // caller will return null
338 }
339 }
340 // Ignore if memory is dead, or self-loop
341 Node *mem = in(MemNode::Memory);
342 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
343 assert(mem != this, "dead loop in MemNode::Ideal");
344
345 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
346 // This memory slice may be dead.
347 // Delay this mem node transformation until the memory is processed.
348 igvn->_worklist.push(this);
349 return NodeSentinel; // caller will return null
350 }
351
352 Node *address = in(MemNode::Address);
353 const Type *t_adr = phase->type(address);
354 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
355
356 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
357 // Unsafe off-heap access with zero address. Remove access and other control users
358 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
359 assert(ctl != nullptr, "unsafe accesses should be control dependent");
360 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
361 Node* u = ctl->fast_out(i);
362 if (u != ctl) {
363 igvn->rehash_node_delayed(u);
364 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
365 --i, imax -= nb;
366 }
367 }
368 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
369 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
370 phase->C->root()->add_req(halt);
371 return this;
372 }
373
374 if (can_reshape && igvn != nullptr &&
375 (igvn->_worklist.member(address) ||
376 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
377 // The address's base and type may change when the address is processed.
378 // Delay this mem node transformation until the address is processed.
379 igvn->_worklist.push(this);
380 return NodeSentinel; // caller will return null
381 }
382
383 // Do NOT remove or optimize the next lines: ensure a new alias index
384 // is allocated for an oop pointer type before Escape Analysis.
385 // Note: C++ will not remove it since the call has side effect.
386 if (t_adr->isa_oopptr()) {
387 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
388 }
389
390 Node* base = nullptr;
391 if (address->is_AddP()) {
392 base = address->in(AddPNode::Base);
393 }
394 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
395 !t_adr->isa_rawptr()) {
396 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
397 // Skip this node optimization if its address has TOP base.
398 return NodeSentinel; // caller will return null
399 }
400
401 // Avoid independent memory operations
402 Node* old_mem = mem;
403
404 // The code which unhooks non-raw memories from complete (macro-expanded)
405 // initializations was removed. After macro-expansion all stores caught
406 // by Initialize node became raw stores and there is no information
407 // which memory slices they modify. So it is unsafe to move any memory
408 // operation above these stores. Also in most cases hooked non-raw memories
409 // were already unhooked by using information from detect_ptr_independence()
410 // and find_previous_store().
411
412 if (mem->is_MergeMem()) {
413 MergeMemNode* mmem = mem->as_MergeMem();
414 const TypePtr *tp = t_adr->is_ptr();
415
416 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
417 }
418
419 if (mem != old_mem) {
420 set_req_X(MemNode::Memory, mem, phase);
421 if (phase->type(mem) == Type::TOP) return NodeSentinel;
422 return this;
423 }
424
425 // let the subclass continue analyzing...
426 return nullptr;
427 }
428
429 // Helper function for proving some simple control dominations.
430 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
431 // Already assumes that 'dom' is available at 'sub', and that 'sub'
432 // is not a constant (dominated by the method's StartNode).
433 // Used by MemNode::find_previous_store to prove that the
434 // control input of a memory operation predates (dominates)
435 // an allocation it wants to look past.
436 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
437 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top())
438 return false; // Conservative answer for dead code
439
440 // Check 'dom'. Skip Proj and CatchProj nodes.
441 dom = dom->find_exact_control(dom);
442 if (dom == nullptr || dom->is_top())
443 return false; // Conservative answer for dead code
444
445 if (dom == sub) {
446 // For the case when, for example, 'sub' is Initialize and the original
447 // 'dom' is Proj node of the 'sub'.
448 return false;
449 }
450
451 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
452 return true;
453
454 // 'dom' dominates 'sub' if its control edge and control edges
455 // of all its inputs dominate or equal to sub's control edge.
456
457 // Currently 'sub' is either Allocate, Initialize or Start nodes.
458 // Or Region for the check in LoadNode::Ideal();
459 // 'sub' should have sub->in(0) != nullptr.
460 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
461 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
462
463 // Get control edge of 'sub'.
464 Node* orig_sub = sub;
465 sub = sub->find_exact_control(sub->in(0));
466 if (sub == nullptr || sub->is_top())
467 return false; // Conservative answer for dead code
468
469 assert(sub->is_CFG(), "expecting control");
470
471 if (sub == dom)
472 return true;
473
474 if (sub->is_Start() || sub->is_Root())
475 return false;
476
477 {
478 // Check all control edges of 'dom'.
479
480 ResourceMark rm;
481 Node_List nlist;
482 Unique_Node_List dom_list;
483
484 dom_list.push(dom);
485 bool only_dominating_controls = false;
486
487 for (uint next = 0; next < dom_list.size(); next++) {
488 Node* n = dom_list.at(next);
489 if (n == orig_sub)
490 return false; // One of dom's inputs dominated by sub.
491 if (!n->is_CFG() && n->pinned()) {
492 // Check only own control edge for pinned non-control nodes.
493 n = n->find_exact_control(n->in(0));
494 if (n == nullptr || n->is_top())
495 return false; // Conservative answer for dead code
496 assert(n->is_CFG(), "expecting control");
497 dom_list.push(n);
498 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
499 only_dominating_controls = true;
500 } else if (n->is_CFG()) {
501 if (n->dominates(sub, nlist))
502 only_dominating_controls = true;
503 else
504 return false;
505 } else {
506 // First, own control edge.
507 Node* m = n->find_exact_control(n->in(0));
508 if (m != nullptr) {
509 if (m->is_top())
510 return false; // Conservative answer for dead code
511 dom_list.push(m);
512 }
513 // Now, the rest of edges.
514 uint cnt = n->req();
515 for (uint i = 1; i < cnt; i++) {
516 m = n->find_exact_control(n->in(i));
517 if (m == nullptr || m->is_top())
518 continue;
519 dom_list.push(m);
520 }
521 }
522 }
523 return only_dominating_controls;
524 }
525 }
526
527 //---------------------detect_ptr_independence---------------------------------
528 // Used by MemNode::find_previous_store to prove that two base
529 // pointers are never equal.
530 // The pointers are accompanied by their associated allocations,
531 // if any, which have been previously discovered by the caller.
532 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
533 Node* p2, AllocateNode* a2,
534 PhaseTransform* phase) {
535 // Attempt to prove that these two pointers cannot be aliased.
536 // They may both manifestly be allocations, and they should differ.
537 // Or, if they are not both allocations, they can be distinct constants.
538 // Otherwise, one is an allocation and the other a pre-existing value.
539 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
540 return (p1 != p2) && p1->is_Con() && p2->is_Con();
541 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
542 return (a1 != a2);
543 } else if (a1 != nullptr) { // one allocation a1
544 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
545 return all_controls_dominate(p2, a1);
546 } else { //(a2 != null) // one allocation a2
547 return all_controls_dominate(p1, a2);
548 }
549 return false;
550 }
551
552
553 // Find an arraycopy ac that produces the memory state represented by parameter mem.
554 // Return ac if
555 // (a) can_see_stored_value=true and ac must have set the value for this load or if
556 // (b) can_see_stored_value=false and ac could have set the value for this load or if
557 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
558 // In case (c) change the parameter mem to the memory input of ac to skip it
559 // when searching stored value.
560 // Otherwise return null.
561 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
562 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
563 if (ac != nullptr) {
564 Node* ld_addp = in(MemNode::Address);
565 Node* src = ac->in(ArrayCopyNode::Src);
566 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
567
568 // This is a load from a cloned array. The corresponding arraycopy ac must
569 // have set the value for the load and we can return ac but only if the load
570 // is known to be within bounds. This is checked below.
571 if (ary_t != nullptr && ld_addp->is_AddP()) {
572 Node* ld_offs = ld_addp->in(AddPNode::Offset);
573 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
574 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
575 jlong elemsize = type2aelembytes(ary_elem);
576
577 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
578 const TypeInt* sizetype = ary_t->size();
579
580 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
581 // The load is known to be within bounds. It receives its value from ac.
582 return ac;
583 }
584 // The load is known to be out-of-bounds.
585 }
586 // The load could be out-of-bounds. It must not be hoisted but must remain
587 // dependent on the runtime range check. This is achieved by returning null.
588 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
589 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
590
591 if (ac->is_arraycopy_validated() ||
592 ac->is_copyof_validated() ||
593 ac->is_copyofrange_validated()) {
594 Node* ld_addp = in(MemNode::Address);
595 if (ld_addp->is_AddP()) {
596 Node* ld_base = ld_addp->in(AddPNode::Address);
597 Node* ld_offs = ld_addp->in(AddPNode::Offset);
598
599 Node* dest = ac->in(ArrayCopyNode::Dest);
600
601 if (dest == ld_base) {
602 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
603 assert(!ld_offs_t->empty(), "dead reference should be checked already");
604 // Take into account vector or unsafe access size
605 jlong ld_size_in_bytes = (jlong)memory_size();
606 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
607 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
608 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
609 return ac;
610 }
611 if (!can_see_stored_value) {
612 mem = ac->in(TypeFunc::Memory);
613 return ac;
614 }
615 }
616 }
617 }
618 }
619 return nullptr;
620 }
621
622 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
623 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
624 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
625 if (ld_alloc != nullptr) {
626 // Check if there is an array copy for a clone
627 Node* mb = mem->in(0);
628 ArrayCopyNode* ac = nullptr;
629 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
630 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
631 ac = mb->in(0)->in(0)->as_ArrayCopy();
632 } else {
633 // Step over GC barrier when ReduceInitialCardMarks is disabled
634 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
635 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
636
637 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
638 ac = control_proj_ac->in(0)->as_ArrayCopy();
639 }
640 }
641
642 if (ac != nullptr && ac->is_clonebasic()) {
643 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
644 if (alloc != nullptr && alloc == ld_alloc) {
645 return ac;
646 }
647 }
648 }
649 }
650 return nullptr;
651 }
652
653 // The logic for reordering loads and stores uses four steps:
654 // (a) Walk carefully past stores and initializations which we
655 // can prove are independent of this load.
656 // (b) Observe that the next memory state makes an exact match
657 // with self (load or store), and locate the relevant store.
658 // (c) Ensure that, if we were to wire self directly to the store,
659 // the optimizer would fold it up somehow.
660 // (d) Do the rewiring, and return, depending on some other part of
661 // the optimizer to fold up the load.
662 // This routine handles steps (a) and (b). Steps (c) and (d) are
663 // specific to loads and stores, so they are handled by the callers.
664 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
665 //
666 Node* MemNode::find_previous_store(PhaseValues* phase) {
667 Node* ctrl = in(MemNode::Control);
668 Node* adr = in(MemNode::Address);
669 intptr_t offset = 0;
670 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
671 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
672
673 if (offset == Type::OffsetBot)
674 return nullptr; // cannot unalias unless there are precise offsets
675
676 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
677 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
678
679 intptr_t size_in_bytes = memory_size();
680
681 Node* mem = in(MemNode::Memory); // start searching here...
682
683 int cnt = 50; // Cycle limiter
684 for (;;) { // While we can dance past unrelated stores...
685 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
686
687 Node* prev = mem;
688 if (mem->is_Store()) {
689 Node* st_adr = mem->in(MemNode::Address);
690 intptr_t st_offset = 0;
691 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
692 if (st_base == nullptr)
693 break; // inscrutable pointer
694
695 // For raw accesses it's not enough to prove that constant offsets don't intersect.
696 // We need the bases to be the equal in order for the offset check to make sense.
697 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
698 break;
699 }
700
701 if (st_offset != offset && st_offset != Type::OffsetBot) {
702 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
703 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
704 if (st_offset >= offset + size_in_bytes ||
705 st_offset <= offset - MAX_STORE ||
706 st_offset <= offset - mem->as_Store()->memory_size()) {
707 // Success: The offsets are provably independent.
708 // (You may ask, why not just test st_offset != offset and be done?
709 // The answer is that stores of different sizes can co-exist
710 // in the same sequence of RawMem effects. We sometimes initialize
711 // a whole 'tile' of array elements with a single jint or jlong.)
712 mem = mem->in(MemNode::Memory);
713 continue; // (a) advance through independent store memory
714 }
715 }
716 if (st_base != base &&
717 detect_ptr_independence(base, alloc,
718 st_base,
719 AllocateNode::Ideal_allocation(st_base),
720 phase)) {
721 // Success: The bases are provably independent.
722 mem = mem->in(MemNode::Memory);
723 continue; // (a) advance through independent store memory
724 }
725
726 // (b) At this point, if the bases or offsets do not agree, we lose,
727 // since we have not managed to prove 'this' and 'mem' independent.
728 if (st_base == base && st_offset == offset) {
729 return mem; // let caller handle steps (c), (d)
730 }
731
732 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
733 InitializeNode* st_init = mem->in(0)->as_Initialize();
734 AllocateNode* st_alloc = st_init->allocation();
735 if (st_alloc == nullptr)
736 break; // something degenerated
737 bool known_identical = false;
738 bool known_independent = false;
739 if (alloc == st_alloc)
740 known_identical = true;
741 else if (alloc != nullptr)
742 known_independent = true;
743 else if (all_controls_dominate(this, st_alloc))
744 known_independent = true;
745
746 if (known_independent) {
747 // The bases are provably independent: Either they are
748 // manifestly distinct allocations, or else the control
749 // of this load dominates the store's allocation.
750 int alias_idx = phase->C->get_alias_index(adr_type());
751 if (alias_idx == Compile::AliasIdxRaw) {
752 mem = st_alloc->in(TypeFunc::Memory);
753 } else {
754 mem = st_init->memory(alias_idx);
755 }
756 continue; // (a) advance through independent store memory
757 }
758
759 // (b) at this point, if we are not looking at a store initializing
760 // the same allocation we are loading from, we lose.
761 if (known_identical) {
762 // From caller, can_see_stored_value will consult find_captured_store.
763 return mem; // let caller handle steps (c), (d)
764 }
765
766 } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
767 if (prev != mem) {
768 // Found an arraycopy but it doesn't affect that load
769 continue;
770 }
771 // Found an arraycopy that may affect that load
772 return mem;
773 } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
774 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
775 if (mem->is_Proj() && mem->in(0)->is_Call()) {
776 // ArrayCopyNodes processed here as well.
777 CallNode *call = mem->in(0)->as_Call();
778 if (!call->may_modify(addr_t, phase)) {
779 mem = call->in(TypeFunc::Memory);
780 continue; // (a) advance through independent call memory
781 }
782 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
783 ArrayCopyNode* ac = nullptr;
784 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
785 break;
786 }
787 mem = mem->in(0)->in(TypeFunc::Memory);
788 continue; // (a) advance through independent MemBar memory
789 } else if (mem->is_ClearArray()) {
790 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
791 // (the call updated 'mem' value)
792 continue; // (a) advance through independent allocation memory
793 } else {
794 // Can not bypass initialization of the instance
795 // we are looking for.
796 return mem;
797 }
798 } else if (mem->is_MergeMem()) {
799 int alias_idx = phase->C->get_alias_index(adr_type());
800 mem = mem->as_MergeMem()->memory_at(alias_idx);
801 continue; // (a) advance through independent MergeMem memory
802 }
803 }
804
805 // Unless there is an explicit 'continue', we must bail out here,
806 // because 'mem' is an inscrutable memory state (e.g., a call).
807 break;
808 }
809
810 return nullptr; // bail out
811 }
812
813 //----------------------calculate_adr_type-------------------------------------
814 // Helper function. Notices when the given type of address hits top or bottom.
815 // Also, asserts a cross-check of the type against the expected address type.
816 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
817 if (t == Type::TOP) return nullptr; // does not touch memory any more?
818 #ifdef ASSERT
819 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
820 #endif
821 const TypePtr* tp = t->isa_ptr();
822 if (tp == nullptr) {
823 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
824 return TypePtr::BOTTOM; // touches lots of memory
825 } else {
826 #ifdef ASSERT
827 // %%%% [phh] We don't check the alias index if cross_check is
828 // TypeRawPtr::BOTTOM. Needs to be investigated.
829 if (cross_check != nullptr &&
830 cross_check != TypePtr::BOTTOM &&
831 cross_check != TypeRawPtr::BOTTOM) {
832 // Recheck the alias index, to see if it has changed (due to a bug).
833 Compile* C = Compile::current();
834 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
835 "must stay in the original alias category");
836 // The type of the address must be contained in the adr_type,
837 // disregarding "null"-ness.
838 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
839 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
840 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
841 "real address must not escape from expected memory type");
842 }
843 #endif
844 return tp;
845 }
846 }
847
848 uint8_t MemNode::barrier_data(const Node* n) {
849 if (n->is_LoadStore()) {
850 return n->as_LoadStore()->barrier_data();
851 } else if (n->is_Mem()) {
852 return n->as_Mem()->barrier_data();
853 }
854 return 0;
855 }
856
857 //=============================================================================
858 // Should LoadNode::Ideal() attempt to remove control edges?
859 bool LoadNode::can_remove_control() const {
860 return !has_pinned_control_dependency();
861 }
862 uint LoadNode::size_of() const { return sizeof(*this); }
863 bool LoadNode::cmp(const Node &n) const {
864 LoadNode& load = (LoadNode &)n;
865 return !Type::cmp(_type, load._type) &&
866 _control_dependency == load._control_dependency &&
867 _mo == load._mo;
868 }
869 const Type *LoadNode::bottom_type() const { return _type; }
870 uint LoadNode::ideal_reg() const {
871 return _type->ideal_reg();
872 }
873
874 #ifndef PRODUCT
875 void LoadNode::dump_spec(outputStream *st) const {
876 MemNode::dump_spec(st);
877 if( !Verbose && !WizardMode ) {
878 // standard dump does this in Verbose and WizardMode
879 st->print(" #"); _type->dump_on(st);
880 }
881 if (!depends_only_on_test()) {
882 st->print(" (does not depend only on test, ");
883 if (control_dependency() == UnknownControl) {
884 st->print("unknown control");
885 } else if (control_dependency() == Pinned) {
886 st->print("pinned");
887 } else if (adr_type() == TypeRawPtr::BOTTOM) {
888 st->print("raw access");
889 } else {
890 st->print("unknown reason");
891 }
892 st->print(")");
893 }
894 }
895 #endif
896
897 #ifdef ASSERT
898 //----------------------------is_immutable_value-------------------------------
899 // Helper function to allow a raw load without control edge for some cases
900 bool LoadNode::is_immutable_value(Node* adr) {
901 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
902 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
903
904 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
905 int offsets[] = {
906 in_bytes(JavaThread::osthread_offset()),
907 in_bytes(JavaThread::threadObj_offset()),
908 in_bytes(JavaThread::vthread_offset()),
909 in_bytes(JavaThread::scopedValueCache_offset()),
910 };
911
912 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
913 if (offset == offsets[i]) {
914 return true;
915 }
916 }
917 }
918
919 return false;
920 }
921 #endif
922
923 //----------------------------LoadNode::make-----------------------------------
924 // Polymorphic factory method:
925 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
926 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
927 Compile* C = gvn.C;
928
929 // sanity check the alias category against the created node type
930 assert(!(adr_type->isa_oopptr() &&
931 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
932 "use LoadKlassNode instead");
933 assert(!(adr_type->isa_aryptr() &&
934 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
935 "use LoadRangeNode instead");
936 // Check control edge of raw loads
937 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
938 // oop will be recorded in oop map if load crosses safepoint
939 rt->isa_oopptr() || is_immutable_value(adr),
940 "raw memory operations should have control edge");
941 LoadNode* load = nullptr;
942 switch (bt) {
943 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
944 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
945 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
946 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
947 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
948 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
949 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
950 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
951 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
952 case T_OBJECT:
953 #ifdef _LP64
954 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
955 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
956 } else
957 #endif
958 {
959 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
960 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
961 }
962 break;
963 default:
964 ShouldNotReachHere();
965 break;
966 }
967 assert(load != nullptr, "LoadNode should have been created");
968 if (unaligned) {
969 load->set_unaligned_access();
970 }
971 if (mismatched) {
972 load->set_mismatched_access();
973 }
974 if (unsafe) {
975 load->set_unsafe_access();
976 }
977 load->set_barrier_data(barrier_data);
978 if (load->Opcode() == Op_LoadN) {
979 Node* ld = gvn.transform(load);
980 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
981 }
982
983 return load;
984 }
985
986 //------------------------------hash-------------------------------------------
987 uint LoadNode::hash() const {
988 // unroll addition of interesting fields
989 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
990 }
991
992 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
993 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
994 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
995 bool is_stable_ary = FoldStableValues &&
996 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
997 tp->isa_aryptr()->is_stable();
998
999 return (eliminate_boxing && non_volatile) || is_stable_ary || tp->is_inlinetypeptr();
1000 }
1001
1002 return false;
1003 }
1004
1005 LoadNode* LoadNode::pin_array_access_node() const {
1006 const TypePtr* adr_type = this->adr_type();
1007 if (adr_type != nullptr && adr_type->isa_aryptr()) {
1008 return clone_pinned();
1009 }
1010 return nullptr;
1011 }
1012
1013 // Is the value loaded previously stored by an arraycopy? If so return
1014 // a load node that reads from the source array so we may be able to
1015 // optimize out the ArrayCopy node later.
1016 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1017 Node* ld_adr = in(MemNode::Address);
1018 intptr_t ld_off = 0;
1019 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1020 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1021 if (ac != nullptr) {
1022 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1023
1024 Node* mem = ac->in(TypeFunc::Memory);
1025 Node* ctl = ac->in(0);
1026 Node* src = ac->in(ArrayCopyNode::Src);
1027
1028 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1029 return nullptr;
1030 }
1031
1032 // load depends on the tests that validate the arraycopy
1033 LoadNode* ld = clone_pinned();
1034 Node* addp = in(MemNode::Address)->clone();
1035 if (ac->as_ArrayCopy()->is_clonebasic()) {
1036 assert(ld_alloc != nullptr, "need an alloc");
1037 assert(addp->is_AddP(), "address must be addp");
1038 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1039 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1040 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1041 addp->set_req(AddPNode::Base, src);
1042 addp->set_req(AddPNode::Address, src);
1043 } else {
1044 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1045 ac->as_ArrayCopy()->is_copyof_validated() ||
1046 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1047 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1048 addp->set_req(AddPNode::Base, src);
1049 addp->set_req(AddPNode::Address, src);
1050
1051 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1052 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1053 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1054
1055 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1056 uint shift = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem));
1057
1058 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1059 #ifdef _LP64
1060 diff = phase->transform(new ConvI2LNode(diff));
1061 #endif
1062 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1063
1064 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1065 addp->set_req(AddPNode::Offset, offset);
1066 }
1067 addp = phase->transform(addp);
1068 #ifdef ASSERT
1069 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1070 ld->_adr_type = adr_type;
1071 #endif
1072 ld->set_req(MemNode::Address, addp);
1073 ld->set_req(0, ctl);
1074 ld->set_req(MemNode::Memory, mem);
1075 return ld;
1076 }
1077 return nullptr;
1078 }
1079
1080
1081 //---------------------------can_see_stored_value------------------------------
1082 // This routine exists to make sure this set of tests is done the same
1083 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1084 // will change the graph shape in a way which makes memory alive twice at the
1085 // same time (uses the Oracle model of aliasing), then some
1086 // LoadXNode::Identity will fold things back to the equivalence-class model
1087 // of aliasing.
1088 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1089 Node* ld_adr = in(MemNode::Address);
1090 intptr_t ld_off = 0;
1091 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1092 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1093 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1094 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1095 // This is more general than load from boxing objects.
1096 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1097 uint alias_idx = atp->index();
1098 Node* result = nullptr;
1099 Node* current = st;
1100 // Skip through chains of MemBarNodes checking the MergeMems for
1101 // new states for the slice of this load. Stop once any other
1102 // kind of node is encountered. Loads from final memory can skip
1103 // through any kind of MemBar but normal loads shouldn't skip
1104 // through MemBarAcquire since the could allow them to move out of
1105 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1106 // because alias info above them may be inaccurate (e.g., due to
1107 // mixed/mismatched unsafe accesses).
1108 bool is_final_mem = !atp->is_rewritable();
1109 while (current->is_Proj()) {
1110 int opc = current->in(0)->Opcode();
1111 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1112 opc == Op_MemBarAcquireLock ||
1113 opc == Op_LoadFence)) ||
1114 opc == Op_MemBarRelease ||
1115 opc == Op_StoreFence ||
1116 opc == Op_MemBarReleaseLock ||
1117 opc == Op_MemBarStoreStore ||
1118 opc == Op_StoreStoreFence) {
1119 Node* mem = current->in(0)->in(TypeFunc::Memory);
1120 if (mem->is_MergeMem()) {
1121 MergeMemNode* merge = mem->as_MergeMem();
1122 Node* new_st = merge->memory_at(alias_idx);
1123 if (new_st == merge->base_memory()) {
1124 // Keep searching
1125 current = new_st;
1126 continue;
1127 }
1128 // Save the new memory state for the slice and fall through
1129 // to exit.
1130 result = new_st;
1131 }
1132 }
1133 break;
1134 }
1135 if (result != nullptr) {
1136 st = result;
1137 }
1138 }
1139
1140 // Loop around twice in the case Load -> Initialize -> Store.
1141 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1142 for (int trip = 0; trip <= 1; trip++) {
1143
1144 if (st->is_Store()) {
1145 Node* st_adr = st->in(MemNode::Address);
1146 if (st_adr != ld_adr) {
1147 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1148 intptr_t st_off = 0;
1149 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1150 if (ld_base == nullptr) return nullptr;
1151 if (st_base == nullptr) return nullptr;
1152 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1153 if (ld_off != st_off) return nullptr;
1154 if (ld_off == Type::OffsetBot) return nullptr;
1155 // Same base, same offset.
1156 // Possible improvement for arrays: check index value instead of absolute offset.
1157
1158 // At this point we have proven something like this setup:
1159 // B = << base >>
1160 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1161 // S = StoreQ(AddP( B , #Off), V)
1162 // (Actually, we haven't yet proven the Q's are the same.)
1163 // In other words, we are loading from a casted version of
1164 // the same pointer-and-offset that we stored to.
1165 // Casted version may carry a dependency and it is respected.
1166 // Thus, we are able to replace L by V.
1167 }
1168 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1169 if (store_Opcode() != st->Opcode()) {
1170 return nullptr;
1171 }
1172 // LoadVector/StoreVector needs additional check to ensure the types match.
1173 if (st->is_StoreVector()) {
1174 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1175 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1176 if (in_vt != out_vt) {
1177 return nullptr;
1178 }
1179 }
1180 return st->in(MemNode::ValueIn);
1181 }
1182
1183 // A load from a freshly-created object always returns zero.
1184 // (This can happen after LoadNode::Ideal resets the load's memory input
1185 // to find_captured_store, which returned InitializeNode::zero_memory.)
1186 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1187 (st->in(0) == ld_alloc) &&
1188 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1189 // return a zero value for the load's basic type
1190 // (This is one of the few places where a generic PhaseTransform
1191 // can create new nodes. Think of it as lazily manifesting
1192 // virtually pre-existing constants.)
1193 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1194 if (default_value != nullptr) {
1195 return default_value;
1196 }
1197 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == nullptr, "default value may not be null");
1198 if (memory_type() != T_VOID) {
1199 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1200 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1201 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1202 // by the ArrayCopyNode.
1203 return phase->zerocon(memory_type());
1204 }
1205 } else {
1206 // TODO: materialize all-zero vector constant
1207 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1208 }
1209 }
1210
1211 // A load from an initialization barrier can match a captured store.
1212 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1213 InitializeNode* init = st->in(0)->as_Initialize();
1214 AllocateNode* alloc = init->allocation();
1215 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1216 // examine a captured store value
1217 st = init->find_captured_store(ld_off, memory_size(), phase);
1218 if (st != nullptr) {
1219 continue; // take one more trip around
1220 }
1221 }
1222 }
1223
1224 // Load boxed value from result of valueOf() call is input parameter.
1225 if (this->is_Load() && ld_adr->is_AddP() &&
1226 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1227 intptr_t ignore = 0;
1228 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1229 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1230 base = bs->step_over_gc_barrier(base);
1231 if (base != nullptr && base->is_Proj() &&
1232 base->as_Proj()->_con == TypeFunc::Parms &&
1233 base->in(0)->is_CallStaticJava() &&
1234 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1235 return base->in(0)->in(TypeFunc::Parms);
1236 }
1237 }
1238
1239 break;
1240 }
1241
1242 return nullptr;
1243 }
1244
1245 //----------------------is_instance_field_load_with_local_phi------------------
1246 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1247 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1248 in(Address)->is_AddP() ) {
1249 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1250 // Only instances and boxed values.
1251 if( t_oop != nullptr &&
1252 (t_oop->is_ptr_to_boxed_value() ||
1253 t_oop->is_known_instance_field()) &&
1254 t_oop->offset() != Type::OffsetBot &&
1255 t_oop->offset() != Type::OffsetTop) {
1256 return true;
1257 }
1258 }
1259 return false;
1260 }
1261
1262 //------------------------------Identity---------------------------------------
1263 // Loads are identity if previous store is to same address
1264 Node* LoadNode::Identity(PhaseGVN* phase) {
1265 // Loading from an InlineType? The InlineType has the values of
1266 // all fields as input. Look for the field with matching offset.
1267 Node* addr = in(Address);
1268 intptr_t offset;
1269 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1270 if (base != nullptr && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) {
1271 Node* value = base->as_InlineType()->field_value_by_offset((int)offset, true);
1272 if (value != nullptr) {
1273 if (Opcode() == Op_LoadN) {
1274 // Encode oop value if we are loading a narrow oop
1275 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1276 value = phase->transform(new EncodePNode(value, bottom_type()));
1277 }
1278 return value;
1279 }
1280 }
1281
1282 // If the previous store-maker is the right kind of Store, and the store is
1283 // to the same address, then we are equal to the value stored.
1284 Node* mem = in(Memory);
1285 Node* value = can_see_stored_value(mem, phase);
1286 if( value ) {
1287 // byte, short & char stores truncate naturally.
1288 // A load has to load the truncated value which requires
1289 // some sort of masking operation and that requires an
1290 // Ideal call instead of an Identity call.
1291 if (memory_size() < BytesPerInt) {
1292 // If the input to the store does not fit with the load's result type,
1293 // it must be truncated via an Ideal call.
1294 if (!phase->type(value)->higher_equal(phase->type(this)))
1295 return this;
1296 }
1297 // (This works even when value is a Con, but LoadNode::Value
1298 // usually runs first, producing the singleton type of the Con.)
1299 if (!has_pinned_control_dependency() || value->is_Con()) {
1300 return value;
1301 } else {
1302 return this;
1303 }
1304 }
1305
1306 if (has_pinned_control_dependency()) {
1307 return this;
1308 }
1309 // Search for an existing data phi which was generated before for the same
1310 // instance's field to avoid infinite generation of phis in a loop.
1311 Node *region = mem->in(0);
1312 if (is_instance_field_load_with_local_phi(region)) {
1313 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1314 int this_index = phase->C->get_alias_index(addr_t);
1315 int this_offset = addr_t->offset();
1316 int this_iid = addr_t->instance_id();
1317 if (!addr_t->is_known_instance() &&
1318 addr_t->is_ptr_to_boxed_value()) {
1319 // Use _idx of address base (could be Phi node) for boxed values.
1320 intptr_t ignore = 0;
1321 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1322 if (base == nullptr) {
1323 return this;
1324 }
1325 this_iid = base->_idx;
1326 }
1327 const Type* this_type = bottom_type();
1328 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1329 Node* phi = region->fast_out(i);
1330 if (phi->is_Phi() && phi != mem &&
1331 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1332 return phi;
1333 }
1334 }
1335 }
1336
1337 return this;
1338 }
1339
1340 // Construct an equivalent unsigned load.
1341 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1342 BasicType bt = T_ILLEGAL;
1343 const Type* rt = nullptr;
1344 switch (Opcode()) {
1345 case Op_LoadUB: return this;
1346 case Op_LoadUS: return this;
1347 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1348 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1349 default:
1350 assert(false, "no unsigned variant: %s", Name());
1351 return nullptr;
1352 }
1353 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1354 raw_adr_type(), rt, bt, _mo, _control_dependency,
1355 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1356 }
1357
1358 // Construct an equivalent signed load.
1359 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1360 BasicType bt = T_ILLEGAL;
1361 const Type* rt = nullptr;
1362 switch (Opcode()) {
1363 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1364 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1365 case Op_LoadB: // fall through
1366 case Op_LoadS: // fall through
1367 case Op_LoadI: // fall through
1368 case Op_LoadL: return this;
1369 default:
1370 assert(false, "no signed variant: %s", Name());
1371 return nullptr;
1372 }
1373 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1374 raw_adr_type(), rt, bt, _mo, _control_dependency,
1375 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1376 }
1377
1378 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1379 BasicType bt = rt->basic_type();
1380 switch (Opcode()) {
1381 case Op_LoadI: return (bt == T_FLOAT);
1382 case Op_LoadL: return (bt == T_DOUBLE);
1383 case Op_LoadF: return (bt == T_INT);
1384 case Op_LoadD: return (bt == T_LONG);
1385
1386 default: return false;
1387 }
1388 }
1389
1390 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1391 BasicType bt = rt->basic_type();
1392 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1393 bool is_mismatched = is_mismatched_access();
1394 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1395 if (raw_type == nullptr) {
1396 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1397 }
1398 const int op = Opcode();
1399 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1400 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1401 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1402 raw_adr_type(), rt, bt, _mo, _control_dependency,
1403 require_atomic_access, is_unaligned_access(), is_mismatched);
1404 }
1405
1406 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1407 BasicType bt = vt->basic_type();
1408 switch (Opcode()) {
1409 case Op_StoreI: return (bt == T_FLOAT);
1410 case Op_StoreL: return (bt == T_DOUBLE);
1411 case Op_StoreF: return (bt == T_INT);
1412 case Op_StoreD: return (bt == T_LONG);
1413
1414 default: return false;
1415 }
1416 }
1417
1418 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1419 BasicType bt = vt->basic_type();
1420 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1421 const int op = Opcode();
1422 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1423 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1424 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1425 raw_adr_type(), val, bt, _mo, require_atomic_access);
1426
1427 bool is_mismatched = is_mismatched_access();
1428 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1429 if (raw_type == nullptr) {
1430 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1431 }
1432 if (is_mismatched) {
1433 st->set_mismatched_access();
1434 }
1435 return st;
1436 }
1437
1438 // We're loading from an object which has autobox behaviour.
1439 // If this object is result of a valueOf call we'll have a phi
1440 // merging a newly allocated object and a load from the cache.
1441 // We want to replace this load with the original incoming
1442 // argument to the valueOf call.
1443 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1444 assert(igvn->C->eliminate_boxing(), "sanity");
1445 intptr_t ignore = 0;
1446 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1447 if ((base == nullptr) || base->is_Phi()) {
1448 // Push the loads from the phi that comes from valueOf up
1449 // through it to allow elimination of the loads and the recovery
1450 // of the original value. It is done in split_through_phi().
1451 return nullptr;
1452 } else if (base->is_Load() ||
1453 (base->is_DecodeN() && base->in(1)->is_Load())) {
1454 // Eliminate the load of boxed value for integer types from the cache
1455 // array by deriving the value from the index into the array.
1456 // Capture the offset of the load and then reverse the computation.
1457
1458 // Get LoadN node which loads a boxing object from 'cache' array.
1459 if (base->is_DecodeN()) {
1460 base = base->in(1);
1461 }
1462 if (!base->in(Address)->is_AddP()) {
1463 return nullptr; // Complex address
1464 }
1465 AddPNode* address = base->in(Address)->as_AddP();
1466 Node* cache_base = address->in(AddPNode::Base);
1467 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1468 // Get ConP node which is static 'cache' field.
1469 cache_base = cache_base->in(1);
1470 }
1471 if ((cache_base != nullptr) && cache_base->is_Con()) {
1472 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1473 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1474 Node* elements[4];
1475 int shift = exact_log2(type2aelembytes(T_OBJECT));
1476 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1477 if (count > 0 && elements[0]->is_Con() &&
1478 (count == 1 ||
1479 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1480 elements[1]->in(2) == igvn->intcon(shift)))) {
1481 ciObjArray* array = base_type->const_oop()->as_obj_array();
1482 // Fetch the box object cache[0] at the base of the array and get its value
1483 ciInstance* box = array->obj_at(0)->as_instance();
1484 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1485 assert(ik->is_box_klass(), "sanity");
1486 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1487 if (ik->nof_nonstatic_fields() == 1) {
1488 // This should be true nonstatic_field_at requires calling
1489 // nof_nonstatic_fields so check it anyway
1490 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1491 BasicType bt = c.basic_type();
1492 // Only integer types have boxing cache.
1493 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1494 bt == T_BYTE || bt == T_SHORT ||
1495 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1496 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1497 if (cache_low != (int)cache_low) {
1498 return nullptr; // should not happen since cache is array indexed by value
1499 }
1500 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1501 if (offset != (int)offset) {
1502 return nullptr; // should not happen since cache is array indexed by value
1503 }
1504 // Add up all the offsets making of the address of the load
1505 Node* result = elements[0];
1506 for (int i = 1; i < count; i++) {
1507 result = igvn->transform(new AddXNode(result, elements[i]));
1508 }
1509 // Remove the constant offset from the address and then
1510 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1511 // remove the scaling of the offset to recover the original index.
1512 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1513 // Peel the shift off directly but wrap it in a dummy node
1514 // since Ideal can't return existing nodes
1515 igvn->_worklist.push(result); // remove dead node later
1516 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1517 } else if (result->is_Add() && result->in(2)->is_Con() &&
1518 result->in(1)->Opcode() == Op_LShiftX &&
1519 result->in(1)->in(2) == igvn->intcon(shift)) {
1520 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1521 // but for boxing cache access we know that X<<Z will not overflow
1522 // (there is range check) so we do this optimizatrion by hand here.
1523 igvn->_worklist.push(result); // remove dead node later
1524 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1525 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1526 } else {
1527 result = new RShiftXNode(result, igvn->intcon(shift));
1528 }
1529 #ifdef _LP64
1530 if (bt != T_LONG) {
1531 result = new ConvL2INode(igvn->transform(result));
1532 }
1533 #else
1534 if (bt == T_LONG) {
1535 result = new ConvI2LNode(igvn->transform(result));
1536 }
1537 #endif
1538 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1539 // Need to preserve unboxing load type if it is unsigned.
1540 switch(this->Opcode()) {
1541 case Op_LoadUB:
1542 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1543 break;
1544 case Op_LoadUS:
1545 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1546 break;
1547 }
1548 return result;
1549 }
1550 }
1551 }
1552 }
1553 }
1554 return nullptr;
1555 }
1556
1557 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1558 Node* region = phi->in(0);
1559 if (region == nullptr) {
1560 return false; // Wait stable graph
1561 }
1562 uint cnt = phi->req();
1563 for (uint i = 1; i < cnt; i++) {
1564 Node* rc = region->in(i);
1565 if (rc == nullptr || phase->type(rc) == Type::TOP)
1566 return false; // Wait stable graph
1567 Node* in = phi->in(i);
1568 if (in == nullptr || phase->type(in) == Type::TOP)
1569 return false; // Wait stable graph
1570 }
1571 return true;
1572 }
1573
1574 //------------------------------split_through_phi------------------------------
1575 // Check whether a call to 'split_through_phi' would split this load through the
1576 // Phi *base*. This method is essentially a copy of the validations performed
1577 // by 'split_through_phi'. The first use of this method was in EA code as part
1578 // of simplification of allocation merges.
1579 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1580 Node* mem = in(Memory);
1581 Node* address = in(Address);
1582 intptr_t ignore = 0;
1583 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1584 bool base_is_phi = (base != nullptr) && base->is_Phi();
1585
1586 if (req() > 3 || !base_is_phi) {
1587 return false;
1588 }
1589
1590 if (!mem->is_Phi()) {
1591 if (!MemNode::all_controls_dominate(mem, base->in(0)))
1592 return false;
1593 } else if (base->in(0) != mem->in(0)) {
1594 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1595 return false;
1596 }
1597 }
1598
1599 return true;
1600 }
1601
1602 //------------------------------split_through_phi------------------------------
1603 // Split instance or boxed field load through Phi.
1604 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1605 if (req() > 3) {
1606 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1607 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1608 return nullptr;
1609 }
1610 Node* mem = in(Memory);
1611 Node* address = in(Address);
1612 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1613
1614 assert((t_oop != nullptr) &&
1615 (ignore_missing_instance_id ||
1616 t_oop->is_known_instance_field() ||
1617 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1618
1619 Compile* C = phase->C;
1620 intptr_t ignore = 0;
1621 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1622 bool base_is_phi = (base != nullptr) && base->is_Phi();
1623 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1624 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1625 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1626
1627 if (!((mem->is_Phi() || base_is_phi) &&
1628 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1629 return nullptr; // Neither memory or base are Phi
1630 }
1631
1632 if (mem->is_Phi()) {
1633 if (!stable_phi(mem->as_Phi(), phase)) {
1634 return nullptr; // Wait stable graph
1635 }
1636 uint cnt = mem->req();
1637 // Check for loop invariant memory.
1638 if (cnt == 3) {
1639 for (uint i = 1; i < cnt; i++) {
1640 Node* in = mem->in(i);
1641 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1642 if (m == mem) {
1643 if (i == 1) {
1644 // if the first edge was a loop, check second edge too.
1645 // If both are replaceable - we are in an infinite loop
1646 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1647 if (n == mem) {
1648 break;
1649 }
1650 }
1651 set_req(Memory, mem->in(cnt - i));
1652 return this; // made change
1653 }
1654 }
1655 }
1656 }
1657 if (base_is_phi) {
1658 if (!stable_phi(base->as_Phi(), phase)) {
1659 return nullptr; // Wait stable graph
1660 }
1661 uint cnt = base->req();
1662 // Check for loop invariant memory.
1663 if (cnt == 3) {
1664 for (uint i = 1; i < cnt; i++) {
1665 if (base->in(i) == base) {
1666 return nullptr; // Wait stable graph
1667 }
1668 }
1669 }
1670 }
1671
1672 // Split through Phi (see original code in loopopts.cpp).
1673 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1674
1675 // Do nothing here if Identity will find a value
1676 // (to avoid infinite chain of value phis generation).
1677 if (this != Identity(phase)) {
1678 return nullptr;
1679 }
1680
1681 // Select Region to split through.
1682 Node* region;
1683 if (!base_is_phi) {
1684 assert(mem->is_Phi(), "sanity");
1685 region = mem->in(0);
1686 // Skip if the region dominates some control edge of the address.
1687 if (!MemNode::all_controls_dominate(address, region))
1688 return nullptr;
1689 } else if (!mem->is_Phi()) {
1690 assert(base_is_phi, "sanity");
1691 region = base->in(0);
1692 // Skip if the region dominates some control edge of the memory.
1693 if (!MemNode::all_controls_dominate(mem, region))
1694 return nullptr;
1695 } else if (base->in(0) != mem->in(0)) {
1696 assert(base_is_phi && mem->is_Phi(), "sanity");
1697 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1698 region = base->in(0);
1699 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1700 region = mem->in(0);
1701 } else {
1702 return nullptr; // complex graph
1703 }
1704 } else {
1705 assert(base->in(0) == mem->in(0), "sanity");
1706 region = mem->in(0);
1707 }
1708
1709 Node* phi = nullptr;
1710 const Type* this_type = this->bottom_type();
1711 PhaseIterGVN* igvn = phase->is_IterGVN();
1712 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1713 int this_index = C->get_alias_index(t_oop);
1714 int this_offset = t_oop->offset();
1715 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1716 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1717 } else if (ignore_missing_instance_id) {
1718 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1719 } else {
1720 return nullptr;
1721 }
1722
1723 for (uint i = 1; i < region->req(); i++) {
1724 Node* x;
1725 Node* the_clone = nullptr;
1726 Node* in = region->in(i);
1727 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1728 in != nullptr && in->is_OuterStripMinedLoop()) {
1729 // No node should go in the outer strip mined loop
1730 in = in->in(LoopNode::EntryControl);
1731 }
1732 if (in == nullptr || in == C->top()) {
1733 x = C->top(); // Dead path? Use a dead data op
1734 } else {
1735 x = this->clone(); // Else clone up the data op
1736 the_clone = x; // Remember for possible deletion.
1737 // Alter data node to use pre-phi inputs
1738 if (this->in(0) == region) {
1739 x->set_req(0, in);
1740 } else {
1741 x->set_req(0, nullptr);
1742 }
1743 if (mem->is_Phi() && (mem->in(0) == region)) {
1744 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1745 }
1746 if (address->is_Phi() && address->in(0) == region) {
1747 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1748 }
1749 if (base_is_phi && (base->in(0) == region)) {
1750 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1751 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1752 x->set_req(Address, adr_x);
1753 }
1754 }
1755 // Check for a 'win' on some paths
1756 const Type *t = x->Value(igvn);
1757
1758 bool singleton = t->singleton();
1759
1760 // See comments in PhaseIdealLoop::split_thru_phi().
1761 if (singleton && t == Type::TOP) {
1762 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1763 }
1764
1765 if (singleton) {
1766 x = igvn->makecon(t);
1767 } else {
1768 // We now call Identity to try to simplify the cloned node.
1769 // Note that some Identity methods call phase->type(this).
1770 // Make sure that the type array is big enough for
1771 // our new node, even though we may throw the node away.
1772 // (This tweaking with igvn only works because x is a new node.)
1773 igvn->set_type(x, t);
1774 // If x is a TypeNode, capture any more-precise type permanently into Node
1775 // otherwise it will be not updated during igvn->transform since
1776 // igvn->type(x) is set to x->Value() already.
1777 x->raise_bottom_type(t);
1778 Node* y = x->Identity(igvn);
1779 if (y != x) {
1780 x = y;
1781 } else {
1782 y = igvn->hash_find_insert(x);
1783 if (y) {
1784 x = y;
1785 } else {
1786 // Else x is a new node we are keeping
1787 // We do not need register_new_node_with_optimizer
1788 // because set_type has already been called.
1789 igvn->_worklist.push(x);
1790 }
1791 }
1792 }
1793 if (x != the_clone && the_clone != nullptr) {
1794 igvn->remove_dead_node(the_clone);
1795 }
1796 phi->set_req(i, x);
1797 }
1798 // Record Phi
1799 igvn->register_new_node_with_optimizer(phi);
1800 return phi;
1801 }
1802
1803 AllocateNode* LoadNode::is_new_object_mark_load() const {
1804 if (Opcode() == Op_LoadX) {
1805 Node* address = in(MemNode::Address);
1806 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1807 Node* mem = in(MemNode::Memory);
1808 if (alloc != nullptr && mem->is_Proj() &&
1809 mem->in(0) != nullptr &&
1810 mem->in(0) == alloc->initialization() &&
1811 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1812 return alloc;
1813 }
1814 }
1815 return nullptr;
1816 }
1817
1818
1819 //------------------------------Ideal------------------------------------------
1820 // If the load is from Field memory and the pointer is non-null, it might be possible to
1821 // zero out the control input.
1822 // If the offset is constant and the base is an object allocation,
1823 // try to hook me up to the exact initializing store.
1824 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1825 if (has_pinned_control_dependency()) {
1826 return nullptr;
1827 }
1828 Node* p = MemNode::Ideal_common(phase, can_reshape);
1829 if (p) return (p == NodeSentinel) ? nullptr : p;
1830
1831 Node* ctrl = in(MemNode::Control);
1832 Node* address = in(MemNode::Address);
1833 bool progress = false;
1834
1835 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1836 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1837
1838 // Skip up past a SafePoint control. Cannot do this for Stores because
1839 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1840 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
1841 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1842 !addr_mark &&
1843 (depends_only_on_test() || has_unknown_control_dependency())) {
1844 ctrl = ctrl->in(0);
1845 set_req(MemNode::Control,ctrl);
1846 progress = true;
1847 }
1848
1849 intptr_t ignore = 0;
1850 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1851 if (base != nullptr
1852 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1853 // Check for useless control edge in some common special cases
1854 if (in(MemNode::Control) != nullptr
1855 && can_remove_control()
1856 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1857 && all_controls_dominate(base, phase->C->start())) {
1858 // A method-invariant, non-null address (constant or 'this' argument).
1859 set_req(MemNode::Control, nullptr);
1860 progress = true;
1861 }
1862 }
1863
1864 Node* mem = in(MemNode::Memory);
1865 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1866
1867 if (can_reshape && (addr_t != nullptr)) {
1868 // try to optimize our memory input
1869 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1870 if (opt_mem != mem) {
1871 set_req_X(MemNode::Memory, opt_mem, phase);
1872 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
1873 return this;
1874 }
1875 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1876 if ((t_oop != nullptr) &&
1877 (t_oop->is_known_instance_field() ||
1878 t_oop->is_ptr_to_boxed_value())) {
1879 PhaseIterGVN *igvn = phase->is_IterGVN();
1880 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
1881 if (igvn->_worklist.member(opt_mem)) {
1882 // Delay this transformation until memory Phi is processed.
1883 igvn->_worklist.push(this);
1884 return nullptr;
1885 }
1886 // Split instance field load through Phi.
1887 Node* result = split_through_phi(phase);
1888 if (result != nullptr) return result;
1889
1890 if (t_oop->is_ptr_to_boxed_value()) {
1891 Node* result = eliminate_autobox(igvn);
1892 if (result != nullptr) return result;
1893 }
1894 }
1895 }
1896
1897 // Is there a dominating load that loads the same value? Leave
1898 // anything that is not a load of a field/array element (like
1899 // barriers etc.) alone
1900 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
1901 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1902 Node *use = mem->fast_out(i);
1903 if (use != this &&
1904 use->Opcode() == Opcode() &&
1905 use->in(0) != nullptr &&
1906 use->in(0) != in(0) &&
1907 use->in(Address) == in(Address)) {
1908 Node* ctl = in(0);
1909 for (int i = 0; i < 10 && ctl != nullptr; i++) {
1910 ctl = IfNode::up_one_dom(ctl);
1911 if (ctl == use->in(0)) {
1912 set_req(0, use->in(0));
1913 return this;
1914 }
1915 }
1916 }
1917 }
1918 }
1919
1920 // Check for prior store with a different base or offset; make Load
1921 // independent. Skip through any number of them. Bail out if the stores
1922 // are in an endless dead cycle and report no progress. This is a key
1923 // transform for Reflection. However, if after skipping through the Stores
1924 // we can't then fold up against a prior store do NOT do the transform as
1925 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1926 // array memory alive twice: once for the hoisted Load and again after the
1927 // bypassed Store. This situation only works if EVERYBODY who does
1928 // anti-dependence work knows how to bypass. I.e. we need all
1929 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1930 // the alias index stuff. So instead, peek through Stores and IFF we can
1931 // fold up, do so.
1932 Node* prev_mem = find_previous_store(phase);
1933 if (prev_mem != nullptr) {
1934 Node* value = can_see_arraycopy_value(prev_mem, phase);
1935 if (value != nullptr) {
1936 return value;
1937 }
1938 }
1939 // Steps (a), (b): Walk past independent stores to find an exact match.
1940 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
1941 // (c) See if we can fold up on the spot, but don't fold up here.
1942 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1943 // just return a prior value, which is done by Identity calls.
1944 if (can_see_stored_value(prev_mem, phase)) {
1945 // Make ready for step (d):
1946 set_req_X(MemNode::Memory, prev_mem, phase);
1947 return this;
1948 }
1949 }
1950
1951 return progress ? this : nullptr;
1952 }
1953
1954 // Helper to recognize certain Klass fields which are invariant across
1955 // some group of array types (e.g., int[] or all T[] where T < Object).
1956 const Type*
1957 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1958 ciKlass* klass) const {
1959 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1960 // The field is Klass::_modifier_flags. Return its (constant) value.
1961 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1962 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1963 return TypeInt::make(klass->modifier_flags());
1964 }
1965 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1966 // The field is Klass::_access_flags. Return its (constant) value.
1967 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1968 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1969 return TypeInt::make(klass->access_flags());
1970 }
1971 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1972 // The field is Klass::_layout_helper. Return its constant value if known.
1973 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1974 return TypeInt::make(klass->layout_helper());
1975 }
1976
1977 // No match.
1978 return nullptr;
1979 }
1980
1981 //------------------------------Value-----------------------------------------
1982 const Type* LoadNode::Value(PhaseGVN* phase) const {
1983 // Either input is TOP ==> the result is TOP
1984 Node* mem = in(MemNode::Memory);
1985 const Type *t1 = phase->type(mem);
1986 if (t1 == Type::TOP) return Type::TOP;
1987 Node* adr = in(MemNode::Address);
1988 const TypePtr* tp = phase->type(adr)->isa_ptr();
1989 if (tp == nullptr || tp->empty()) return Type::TOP;
1990 int off = tp->offset();
1991 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1992 Compile* C = phase->C;
1993
1994 // Try to guess loaded type from pointer type
1995 if (tp->isa_aryptr()) {
1996 const TypeAryPtr* ary = tp->is_aryptr();
1997 const Type* t = ary->elem();
1998
1999 // Determine whether the reference is beyond the header or not, by comparing
2000 // the offset against the offset of the start of the array's data.
2001 // Different array types begin at slightly different offsets (12 vs. 16).
2002 // We choose T_BYTE as an example base type that is least restrictive
2003 // as to alignment, which will therefore produce the smallest
2004 // possible base offset.
2005 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2006 const bool off_beyond_header = (off >= min_base_off);
2007
2008 // Try to constant-fold a stable array element.
2009 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2010 // Make sure the reference is not into the header and the offset is constant
2011 ciObject* aobj = ary->const_oop();
2012 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2013 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2014 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2015 stable_dimension,
2016 memory_type(), is_unsigned());
2017 if (con_type != nullptr) {
2018 return con_type;
2019 }
2020 }
2021 }
2022
2023 // Don't do this for integer types. There is only potential profit if
2024 // the element type t is lower than _type; that is, for int types, if _type is
2025 // more restrictive than t. This only happens here if one is short and the other
2026 // char (both 16 bits), and in those cases we've made an intentional decision
2027 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2028 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2029 //
2030 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2031 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2032 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2033 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2034 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2035 // In fact, that could have been the original type of p1, and p1 could have
2036 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2037 // expression (LShiftL quux 3) independently optimized to the constant 8.
2038 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2039 && (_type->isa_vect() == nullptr)
2040 && !ary->is_flat()
2041 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2042 // t might actually be lower than _type, if _type is a unique
2043 // concrete subclass of abstract class t.
2044 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2045 const Type* jt = t->join_speculative(_type);
2046 // In any case, do not allow the join, per se, to empty out the type.
2047 if (jt->empty() && !t->empty()) {
2048 // This can happen if a interface-typed array narrows to a class type.
2049 jt = _type;
2050 }
2051 #ifdef ASSERT
2052 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2053 // The pointers in the autobox arrays are always non-null
2054 Node* base = adr->in(AddPNode::Base);
2055 if ((base != nullptr) && base->is_DecodeN()) {
2056 // Get LoadN node which loads IntegerCache.cache field
2057 base = base->in(1);
2058 }
2059 if ((base != nullptr) && base->is_Con()) {
2060 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2061 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2062 // It could be narrow oop
2063 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2064 }
2065 }
2066 }
2067 #endif
2068 return jt;
2069 }
2070 }
2071 } else if (tp->base() == Type::InstPtr) {
2072 assert( off != Type::OffsetBot ||
2073 // arrays can be cast to Objects
2074 !tp->isa_instptr() ||
2075 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2076 // Default value load
2077 tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() ||
2078 // unsafe field access may not have a constant offset
2079 C->has_unsafe_access(),
2080 "Field accesses must be precise" );
2081 // For oop loads, we expect the _type to be precise.
2082
2083 const TypeInstPtr* tinst = tp->is_instptr();
2084 BasicType bt = memory_type();
2085
2086 // Optimize loads from constant fields.
2087 ciObject* const_oop = tinst->const_oop();
2088 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2089 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2090 if (con_type != nullptr) {
2091 return con_type;
2092 }
2093 }
2094 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2095 assert(off != Type::OffsetBot ||
2096 !tp->isa_instklassptr() ||
2097 // arrays can be cast to Objects
2098 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2099 // also allow array-loading from the primary supertype
2100 // array during subtype checks
2101 Opcode() == Op_LoadKlass,
2102 "Field accesses must be precise");
2103 // For klass/static loads, we expect the _type to be precise
2104 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
2105 if (adr->is_Load() && off == 0) {
2106 /* With mirrors being an indirect in the Klass*
2107 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2108 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2109 *
2110 * So check the type and klass of the node before the LoadP.
2111 */
2112 Node* adr2 = adr->in(MemNode::Address);
2113 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2114 if (tkls != nullptr) {
2115 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2116 ciKlass* klass = tkls->exact_klass();
2117 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2118 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2119 return TypeInstPtr::make(klass->java_mirror());
2120 }
2121 }
2122 } else {
2123 // Check for a load of the default value offset from the InlineKlassFixedBlock:
2124 // LoadI(LoadP(inline_klass, adr_inlineklass_fixed_block_offset), default_value_offset_offset)
2125 // TODO 8325106 remove?
2126 intptr_t offset = 0;
2127 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2128 if (base != nullptr && base->is_Load() && offset == in_bytes(InlineKlass::default_value_offset_offset())) {
2129 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
2130 if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact() && tkls->exact_klass()->is_inlinetype() &&
2131 tkls->offset() == in_bytes(InstanceKlass::adr_inlineklass_fixed_block_offset())) {
2132 assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
2133 assert(Opcode() == Op_LoadI, "must load an int from fixed block");
2134 return TypeInt::make(tkls->exact_klass()->as_inline_klass()->default_value_offset());
2135 }
2136 }
2137 }
2138 }
2139
2140 const TypeKlassPtr *tkls = tp->isa_klassptr();
2141 if (tkls != nullptr) {
2142 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2143 ciKlass* klass = tkls->exact_klass();
2144 // We are loading a field from a Klass metaobject whose identity
2145 // is known at compile time (the type is "exact" or "precise").
2146 // Check for fields we know are maintained as constants by the VM.
2147 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2148 // The field is Klass::_super_check_offset. Return its (constant) value.
2149 // (Folds up type checking code.)
2150 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2151 return TypeInt::make(klass->super_check_offset());
2152 }
2153 // Compute index into primary_supers array
2154 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2155 // Check for overflowing; use unsigned compare to handle the negative case.
2156 if( depth < ciKlass::primary_super_limit() ) {
2157 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2158 // (Folds up type checking code.)
2159 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2160 ciKlass *ss = klass->super_of_depth(depth);
2161 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2162 }
2163 const Type* aift = load_array_final_field(tkls, klass);
2164 if (aift != nullptr) return aift;
2165 }
2166
2167 // We can still check if we are loading from the primary_supers array at a
2168 // shallow enough depth. Even though the klass is not exact, entries less
2169 // than or equal to its super depth are correct.
2170 if (tkls->is_loaded()) {
2171 ciKlass* klass = nullptr;
2172 if (tkls->isa_instklassptr()) {
2173 klass = tkls->is_instklassptr()->instance_klass();
2174 } else {
2175 int dims;
2176 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2177 if (inner->isa_instklassptr()) {
2178 klass = inner->is_instklassptr()->instance_klass();
2179 klass = ciObjArrayKlass::make(klass, dims);
2180 }
2181 }
2182 if (klass != nullptr) {
2183 // Compute index into primary_supers array
2184 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2185 // Check for overflowing; use unsigned compare to handle the negative case.
2186 if (depth < ciKlass::primary_super_limit() &&
2187 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2188 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2189 // (Folds up type checking code.)
2190 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2191 ciKlass *ss = klass->super_of_depth(depth);
2192 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2193 }
2194 }
2195 }
2196
2197 // If the type is enough to determine that the thing is not an array,
2198 // we can give the layout_helper a positive interval type.
2199 // This will help short-circuit some reflective code.
2200 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2201 tkls->isa_instklassptr() && // not directly typed as an array
2202 !tkls->is_instklassptr()->instance_klass()->is_java_lang_Object() // not the supertype of all T[] and specifically not Serializable & Cloneable
2203 ) {
2204 // Note: When interfaces are reliable, we can narrow the interface
2205 // test to (klass != Serializable && klass != Cloneable).
2206 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2207 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2208 // The key property of this type is that it folds up tests
2209 // for array-ness, since it proves that the layout_helper is positive.
2210 // Thus, a generic value like the basic object layout helper works fine.
2211 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2212 }
2213 }
2214
2215 // If we are loading from a freshly-allocated object, produce a zero,
2216 // if the load is provably beyond the header of the object.
2217 // (Also allow a variable load from a fresh array to produce zero.)
2218 const TypeOopPtr *tinst = tp->isa_oopptr();
2219 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2220 bool is_boxed_value = (tinst != nullptr) && tinst->is_ptr_to_boxed_value();
2221 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2222 Node* value = can_see_stored_value(mem,phase);
2223 if (value != nullptr && value->is_Con()) {
2224 assert(value->bottom_type()->higher_equal(_type),"sanity");
2225 return value->bottom_type();
2226 }
2227 }
2228
2229 bool is_vect = (_type->isa_vect() != nullptr);
2230 if (is_instance && !is_vect) {
2231 // If we have an instance type and our memory input is the
2232 // programs's initial memory state, there is no matching store,
2233 // so just return a zero of the appropriate type -
2234 // except if it is vectorized - then we have no zero constant.
2235 Node *mem = in(MemNode::Memory);
2236 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2237 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2238 return Type::get_zero_type(_type->basic_type());
2239 }
2240 }
2241 Node* alloc = is_new_object_mark_load();
2242 if (alloc != nullptr) {
2243 if (EnableValhalla) {
2244 // The mark word may contain property bits (inline, flat, null-free)
2245 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2246 const TypeKlassPtr* tkls = phase->type(klass_node)->isa_klassptr();
2247 if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact()) {
2248 return TypeX::make(tkls->exact_klass()->prototype_header().value());
2249 }
2250 } else {
2251 return TypeX::make(markWord::prototype().value());
2252 }
2253 }
2254
2255 return _type;
2256 }
2257
2258 //------------------------------match_edge-------------------------------------
2259 // Do we Match on this edge index or not? Match only the address.
2260 uint LoadNode::match_edge(uint idx) const {
2261 return idx == MemNode::Address;
2262 }
2263
2264 //--------------------------LoadBNode::Ideal--------------------------------------
2265 //
2266 // If the previous store is to the same address as this load,
2267 // and the value stored was larger than a byte, replace this load
2268 // with the value stored truncated to a byte. If no truncation is
2269 // needed, the replacement is done in LoadNode::Identity().
2270 //
2271 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2272 Node* mem = in(MemNode::Memory);
2273 Node* value = can_see_stored_value(mem,phase);
2274 if (value != nullptr) {
2275 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2276 if (narrow != value) {
2277 return narrow;
2278 }
2279 }
2280 // Identity call will handle the case where truncation is not needed.
2281 return LoadNode::Ideal(phase, can_reshape);
2282 }
2283
2284 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2285 Node* mem = in(MemNode::Memory);
2286 Node* value = can_see_stored_value(mem,phase);
2287 if (value != nullptr && value->is_Con() &&
2288 !value->bottom_type()->higher_equal(_type)) {
2289 // If the input to the store does not fit with the load's result type,
2290 // it must be truncated. We can't delay until Ideal call since
2291 // a singleton Value is needed for split_thru_phi optimization.
2292 int con = value->get_int();
2293 return TypeInt::make((con << 24) >> 24);
2294 }
2295 return LoadNode::Value(phase);
2296 }
2297
2298 //--------------------------LoadUBNode::Ideal-------------------------------------
2299 //
2300 // If the previous store is to the same address as this load,
2301 // and the value stored was larger than a byte, replace this load
2302 // with the value stored truncated to a byte. If no truncation is
2303 // needed, the replacement is done in LoadNode::Identity().
2304 //
2305 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2306 Node* mem = in(MemNode::Memory);
2307 Node* value = can_see_stored_value(mem, phase);
2308 if (value != nullptr) {
2309 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2310 if (narrow != value) {
2311 return narrow;
2312 }
2313 }
2314 // Identity call will handle the case where truncation is not needed.
2315 return LoadNode::Ideal(phase, can_reshape);
2316 }
2317
2318 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2319 Node* mem = in(MemNode::Memory);
2320 Node* value = can_see_stored_value(mem,phase);
2321 if (value != nullptr && value->is_Con() &&
2322 !value->bottom_type()->higher_equal(_type)) {
2323 // If the input to the store does not fit with the load's result type,
2324 // it must be truncated. We can't delay until Ideal call since
2325 // a singleton Value is needed for split_thru_phi optimization.
2326 int con = value->get_int();
2327 return TypeInt::make(con & 0xFF);
2328 }
2329 return LoadNode::Value(phase);
2330 }
2331
2332 //--------------------------LoadUSNode::Ideal-------------------------------------
2333 //
2334 // If the previous store is to the same address as this load,
2335 // and the value stored was larger than a char, replace this load
2336 // with the value stored truncated to a char. If no truncation is
2337 // needed, the replacement is done in LoadNode::Identity().
2338 //
2339 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2340 Node* mem = in(MemNode::Memory);
2341 Node* value = can_see_stored_value(mem,phase);
2342 if (value != nullptr) {
2343 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2344 if (narrow != value) {
2345 return narrow;
2346 }
2347 }
2348 // Identity call will handle the case where truncation is not needed.
2349 return LoadNode::Ideal(phase, can_reshape);
2350 }
2351
2352 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2353 Node* mem = in(MemNode::Memory);
2354 Node* value = can_see_stored_value(mem,phase);
2355 if (value != nullptr && value->is_Con() &&
2356 !value->bottom_type()->higher_equal(_type)) {
2357 // If the input to the store does not fit with the load's result type,
2358 // it must be truncated. We can't delay until Ideal call since
2359 // a singleton Value is needed for split_thru_phi optimization.
2360 int con = value->get_int();
2361 return TypeInt::make(con & 0xFFFF);
2362 }
2363 return LoadNode::Value(phase);
2364 }
2365
2366 //--------------------------LoadSNode::Ideal--------------------------------------
2367 //
2368 // If the previous store is to the same address as this load,
2369 // and the value stored was larger than a short, replace this load
2370 // with the value stored truncated to a short. If no truncation is
2371 // needed, the replacement is done in LoadNode::Identity().
2372 //
2373 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2374 Node* mem = in(MemNode::Memory);
2375 Node* value = can_see_stored_value(mem,phase);
2376 if (value != nullptr) {
2377 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2378 if (narrow != value) {
2379 return narrow;
2380 }
2381 }
2382 // Identity call will handle the case where truncation is not needed.
2383 return LoadNode::Ideal(phase, can_reshape);
2384 }
2385
2386 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2387 Node* mem = in(MemNode::Memory);
2388 Node* value = can_see_stored_value(mem,phase);
2389 if (value != nullptr && value->is_Con() &&
2390 !value->bottom_type()->higher_equal(_type)) {
2391 // If the input to the store does not fit with the load's result type,
2392 // it must be truncated. We can't delay until Ideal call since
2393 // a singleton Value is needed for split_thru_phi optimization.
2394 int con = value->get_int();
2395 return TypeInt::make((con << 16) >> 16);
2396 }
2397 return LoadNode::Value(phase);
2398 }
2399
2400 //=============================================================================
2401 //----------------------------LoadKlassNode::make------------------------------
2402 // Polymorphic factory method:
2403 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
2404 const TypeKlassPtr* tk) {
2405 // sanity check the alias category against the created node type
2406 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2407 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2408 #ifdef _LP64
2409 if (adr_type->is_ptr_to_narrowklass()) {
2410 assert(UseCompressedClassPointers, "no compressed klasses");
2411 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2412 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2413 }
2414 #endif
2415 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2416 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2417 }
2418
2419 //------------------------------Value------------------------------------------
2420 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2421 return klass_value_common(phase);
2422 }
2423
2424 // In most cases, LoadKlassNode does not have the control input set. If the control
2425 // input is set, it must not be removed (by LoadNode::Ideal()).
2426 bool LoadKlassNode::can_remove_control() const {
2427 return false;
2428 }
2429
2430 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2431 // Either input is TOP ==> the result is TOP
2432 const Type *t1 = phase->type( in(MemNode::Memory) );
2433 if (t1 == Type::TOP) return Type::TOP;
2434 Node *adr = in(MemNode::Address);
2435 const Type *t2 = phase->type( adr );
2436 if (t2 == Type::TOP) return Type::TOP;
2437 const TypePtr *tp = t2->is_ptr();
2438 if (TypePtr::above_centerline(tp->ptr()) ||
2439 tp->ptr() == TypePtr::Null) return Type::TOP;
2440
2441 // Return a more precise klass, if possible
2442 const TypeInstPtr *tinst = tp->isa_instptr();
2443 if (tinst != nullptr) {
2444 ciInstanceKlass* ik = tinst->instance_klass();
2445 int offset = tinst->offset();
2446 if (ik == phase->C->env()->Class_klass()
2447 && (offset == java_lang_Class::klass_offset() ||
2448 offset == java_lang_Class::array_klass_offset())) {
2449 // We are loading a special hidden field from a Class mirror object,
2450 // the field which points to the VM's Klass metaobject.
2451 bool is_null_free_array = false;
2452 ciType* t = tinst->java_mirror_type(&is_null_free_array);
2453 // java_mirror_type returns non-null for compile-time Class constants.
2454 if (t != nullptr) {
2455 // constant oop => constant klass
2456 if (offset == java_lang_Class::array_klass_offset()) {
2457 if (t->is_void()) {
2458 // We cannot create a void array. Since void is a primitive type return null
2459 // klass. Users of this result need to do a null check on the returned klass.
2460 return TypePtr::NULL_PTR;
2461 }
2462 const TypeKlassPtr* tklass = TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2463 if (is_null_free_array) {
2464 tklass = tklass->is_aryklassptr()->cast_to_null_free();
2465 }
2466 return tklass;
2467 }
2468 if (!t->is_klass()) {
2469 // a primitive Class (e.g., int.class) has null for a klass field
2470 return TypePtr::NULL_PTR;
2471 }
2472 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2473 const TypeKlassPtr* tklass = TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2474 if (is_null_free_array) {
2475 tklass = tklass->is_aryklassptr()->cast_to_null_free();
2476 }
2477 return tklass;
2478 }
2479 // non-constant mirror, so we can't tell what's going on
2480 }
2481 if (!tinst->is_loaded())
2482 return _type; // Bail out if not loaded
2483 if (offset == oopDesc::klass_offset_in_bytes()) {
2484 return tinst->as_klass_type(true);
2485 }
2486 }
2487
2488 // Check for loading klass from an array
2489 const TypeAryPtr* tary = tp->isa_aryptr();
2490 if (tary != nullptr &&
2491 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2492 return tary->as_klass_type(true);
2493 }
2494
2495 // Check for loading klass from an array klass
2496 const TypeKlassPtr *tkls = tp->isa_klassptr();
2497 if (tkls != nullptr && !StressReflectiveCode) {
2498 if (!tkls->is_loaded())
2499 return _type; // Bail out if not loaded
2500 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2501 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2502 // // Always returning precise element type is incorrect,
2503 // // e.g., element type could be object and array may contain strings
2504 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2505
2506 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2507 // according to the element type's subclassing.
2508 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2509 }
2510 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2511 tkls->offset() == in_bytes(Klass::super_offset())) {
2512 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2513 // The field is Klass::_super. Return its (constant) value.
2514 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2515 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2516 }
2517 }
2518
2519 // Bailout case
2520 return LoadNode::Value(phase);
2521 }
2522
2523 //------------------------------Identity---------------------------------------
2524 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2525 // Also feed through the klass in Allocate(...klass...)._klass.
2526 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2527 return klass_identity_common(phase);
2528 }
2529
2530 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2531 Node* x = LoadNode::Identity(phase);
2532 if (x != this) return x;
2533
2534 // Take apart the address into an oop and offset.
2535 // Return 'this' if we cannot.
2536 Node* adr = in(MemNode::Address);
2537 intptr_t offset = 0;
2538 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2539 if (base == nullptr) return this;
2540 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2541 if (toop == nullptr) return this;
2542
2543 // Step over potential GC barrier for OopHandle resolve
2544 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2545 if (bs->is_gc_barrier_node(base)) {
2546 base = bs->step_over_gc_barrier(base);
2547 }
2548
2549 // We can fetch the klass directly through an AllocateNode.
2550 // This works even if the klass is not constant (clone or newArray).
2551 if (offset == oopDesc::klass_offset_in_bytes()) {
2552 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2553 if (allocated_klass != nullptr) {
2554 return allocated_klass;
2555 }
2556 }
2557
2558 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2559 // See inline_native_Class_query for occurrences of these patterns.
2560 // Java Example: x.getClass().isAssignableFrom(y)
2561 //
2562 // This improves reflective code, often making the Class
2563 // mirror go completely dead. (Current exception: Class
2564 // mirrors may appear in debug info, but we could clean them out by
2565 // introducing a new debug info operator for Klass.java_mirror).
2566
2567 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2568 && offset == java_lang_Class::klass_offset()) {
2569 if (base->is_Load()) {
2570 Node* base2 = base->in(MemNode::Address);
2571 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2572 Node* adr2 = base2->in(MemNode::Address);
2573 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2574 if (tkls != nullptr && !tkls->empty()
2575 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2576 && adr2->is_AddP()
2577 ) {
2578 int mirror_field = in_bytes(Klass::java_mirror_offset());
2579 if (tkls->offset() == mirror_field) {
2580 return adr2->in(AddPNode::Base);
2581 }
2582 }
2583 }
2584 }
2585 }
2586
2587 return this;
2588 }
2589
2590 LoadNode* LoadNode::clone_pinned() const {
2591 LoadNode* ld = clone()->as_Load();
2592 ld->_control_dependency = UnknownControl;
2593 return ld;
2594 }
2595
2596
2597 //------------------------------Value------------------------------------------
2598 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2599 const Type *t = klass_value_common(phase);
2600 if (t == Type::TOP)
2601 return t;
2602
2603 return t->make_narrowklass();
2604 }
2605
2606 //------------------------------Identity---------------------------------------
2607 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2608 // Also feed through the klass in Allocate(...klass...)._klass.
2609 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2610 Node *x = klass_identity_common(phase);
2611
2612 const Type *t = phase->type( x );
2613 if( t == Type::TOP ) return x;
2614 if( t->isa_narrowklass()) return x;
2615 assert (!t->isa_narrowoop(), "no narrow oop here");
2616
2617 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2618 }
2619
2620 //------------------------------Value-----------------------------------------
2621 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2622 // Either input is TOP ==> the result is TOP
2623 const Type *t1 = phase->type( in(MemNode::Memory) );
2624 if( t1 == Type::TOP ) return Type::TOP;
2625 Node *adr = in(MemNode::Address);
2626 const Type *t2 = phase->type( adr );
2627 if( t2 == Type::TOP ) return Type::TOP;
2628 const TypePtr *tp = t2->is_ptr();
2629 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2630 const TypeAryPtr *tap = tp->isa_aryptr();
2631 if( !tap ) return _type;
2632 return tap->size();
2633 }
2634
2635 //-------------------------------Ideal---------------------------------------
2636 // Feed through the length in AllocateArray(...length...)._length.
2637 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2638 Node* p = MemNode::Ideal_common(phase, can_reshape);
2639 if (p) return (p == NodeSentinel) ? nullptr : p;
2640
2641 // Take apart the address into an oop and offset.
2642 // Return 'this' if we cannot.
2643 Node* adr = in(MemNode::Address);
2644 intptr_t offset = 0;
2645 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2646 if (base == nullptr) return nullptr;
2647 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2648 if (tary == nullptr) return nullptr;
2649
2650 // We can fetch the length directly through an AllocateArrayNode.
2651 // This works even if the length is not constant (clone or newArray).
2652 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2653 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2654 if (alloc != nullptr) {
2655 Node* allocated_length = alloc->Ideal_length();
2656 Node* len = alloc->make_ideal_length(tary, phase);
2657 if (allocated_length != len) {
2658 // New CastII improves on this.
2659 return len;
2660 }
2661 }
2662 }
2663
2664 return nullptr;
2665 }
2666
2667 //------------------------------Identity---------------------------------------
2668 // Feed through the length in AllocateArray(...length...)._length.
2669 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2670 Node* x = LoadINode::Identity(phase);
2671 if (x != this) return x;
2672
2673 // Take apart the address into an oop and offset.
2674 // Return 'this' if we cannot.
2675 Node* adr = in(MemNode::Address);
2676 intptr_t offset = 0;
2677 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2678 if (base == nullptr) return this;
2679 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2680 if (tary == nullptr) return this;
2681
2682 // We can fetch the length directly through an AllocateArrayNode.
2683 // This works even if the length is not constant (clone or newArray).
2684 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2685 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2686 if (alloc != nullptr) {
2687 Node* allocated_length = alloc->Ideal_length();
2688 // Do not allow make_ideal_length to allocate a CastII node.
2689 Node* len = alloc->make_ideal_length(tary, phase, false);
2690 if (allocated_length == len) {
2691 // Return allocated_length only if it would not be improved by a CastII.
2692 return allocated_length;
2693 }
2694 }
2695 }
2696
2697 return this;
2698
2699 }
2700
2701 //=============================================================================
2702 //---------------------------StoreNode::make-----------------------------------
2703 // Polymorphic factory method:
2704 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) {
2705 assert((mo == unordered || mo == release), "unexpected");
2706 Compile* C = gvn.C;
2707 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2708 ctl != nullptr, "raw memory operations should have control edge");
2709
2710 switch (bt) {
2711 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2712 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2713 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2714 case T_CHAR:
2715 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2716 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2717 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2718 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2719 case T_METADATA:
2720 case T_ADDRESS:
2721 case T_OBJECT:
2722 #ifdef _LP64
2723 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2724 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2725 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2726 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2727 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2728 adr->bottom_type()->isa_rawptr())) {
2729 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2730 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2731 }
2732 #endif
2733 {
2734 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2735 }
2736 default:
2737 ShouldNotReachHere();
2738 return (StoreNode*)nullptr;
2739 }
2740 }
2741
2742 //--------------------------bottom_type----------------------------------------
2743 const Type *StoreNode::bottom_type() const {
2744 return Type::MEMORY;
2745 }
2746
2747 //------------------------------hash-------------------------------------------
2748 uint StoreNode::hash() const {
2749 // unroll addition of interesting fields
2750 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2751
2752 // Since they are not commoned, do not hash them:
2753 return NO_HASH;
2754 }
2755
2756 //------------------------------Ideal------------------------------------------
2757 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2758 // When a store immediately follows a relevant allocation/initialization,
2759 // try to capture it into the initialization, or hoist it above.
2760 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2761 Node* p = MemNode::Ideal_common(phase, can_reshape);
2762 if (p) return (p == NodeSentinel) ? nullptr : p;
2763
2764 Node* mem = in(MemNode::Memory);
2765 Node* address = in(MemNode::Address);
2766 Node* value = in(MemNode::ValueIn);
2767 // Back-to-back stores to same address? Fold em up. Generally
2768 // unsafe if I have intervening uses... Also disallowed for StoreCM
2769 // since they must follow each StoreP operation. Redundant StoreCMs
2770 // are eliminated just before matching in final_graph_reshape.
2771 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
2772 Node* st = mem;
2773 // If Store 'st' has more than one use, we cannot fold 'st' away.
2774 // For example, 'st' might be the final state at a conditional
2775 // return. Or, 'st' might be used by some node which is live at
2776 // the same time 'st' is live, which might be unschedulable. So,
2777 // require exactly ONE user until such time as we clone 'mem' for
2778 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2779 // true).
2780 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2781 // Looking at a dead closed cycle of memory?
2782 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2783 assert(Opcode() == st->Opcode() ||
2784 st->Opcode() == Op_StoreVector ||
2785 Opcode() == Op_StoreVector ||
2786 st->Opcode() == Op_StoreVectorScatter ||
2787 Opcode() == Op_StoreVectorScatter ||
2788 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2789 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2790 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2791 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2792 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2793 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2794
2795 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2796 st->as_Store()->memory_size() <= this->memory_size()) {
2797 Node* use = st->raw_out(0);
2798 if (phase->is_IterGVN()) {
2799 phase->is_IterGVN()->rehash_node_delayed(use);
2800 }
2801 // It's OK to do this in the parser, since DU info is always accurate,
2802 // and the parser always refers to nodes via SafePointNode maps.
2803 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2804 return this;
2805 }
2806 st = st->in(MemNode::Memory);
2807 }
2808 }
2809
2810
2811 // Capture an unaliased, unconditional, simple store into an initializer.
2812 // Or, if it is independent of the allocation, hoist it above the allocation.
2813 if (ReduceFieldZeroing && /*can_reshape &&*/
2814 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2815 InitializeNode* init = mem->in(0)->as_Initialize();
2816 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2817 if (offset > 0) {
2818 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2819 // If the InitializeNode captured me, it made a raw copy of me,
2820 // and I need to disappear.
2821 if (moved != nullptr) {
2822 // %%% hack to ensure that Ideal returns a new node:
2823 mem = MergeMemNode::make(mem);
2824 return mem; // fold me away
2825 }
2826 }
2827 }
2828
2829 // Fold reinterpret cast into memory operation:
2830 // StoreX mem (MoveY2X v) => StoreY mem v
2831 if (value->is_Move()) {
2832 const Type* vt = value->in(1)->bottom_type();
2833 if (has_reinterpret_variant(vt)) {
2834 if (phase->C->post_loop_opts_phase()) {
2835 return convert_to_reinterpret_store(*phase, value->in(1), vt);
2836 } else {
2837 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2838 }
2839 }
2840 }
2841
2842 return nullptr; // No further progress
2843 }
2844
2845 //------------------------------Value-----------------------------------------
2846 const Type* StoreNode::Value(PhaseGVN* phase) const {
2847 // Either input is TOP ==> the result is TOP
2848 const Type *t1 = phase->type( in(MemNode::Memory) );
2849 if( t1 == Type::TOP ) return Type::TOP;
2850 const Type *t2 = phase->type( in(MemNode::Address) );
2851 if( t2 == Type::TOP ) return Type::TOP;
2852 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2853 if( t3 == Type::TOP ) return Type::TOP;
2854 return Type::MEMORY;
2855 }
2856
2857 //------------------------------Identity---------------------------------------
2858 // Remove redundant stores:
2859 // Store(m, p, Load(m, p)) changes to m.
2860 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2861 Node* StoreNode::Identity(PhaseGVN* phase) {
2862 Node* mem = in(MemNode::Memory);
2863 Node* adr = in(MemNode::Address);
2864 Node* val = in(MemNode::ValueIn);
2865
2866 Node* result = this;
2867
2868 // Load then Store? Then the Store is useless
2869 if (val->is_Load() &&
2870 val->in(MemNode::Address)->eqv_uncast(adr) &&
2871 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2872 val->as_Load()->store_Opcode() == Opcode()) {
2873 result = mem;
2874 }
2875
2876 // Two stores in a row of the same value?
2877 if (result == this &&
2878 mem->is_Store() &&
2879 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2880 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2881 mem->Opcode() == Opcode()) {
2882 result = mem;
2883 }
2884
2885 // Store of zero anywhere into a freshly-allocated object?
2886 // Then the store is useless.
2887 // (It must already have been captured by the InitializeNode.)
2888 if (result == this && ReduceFieldZeroing) {
2889 // a newly allocated object is already all-zeroes everywhere
2890 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2891 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2892 result = mem;
2893 }
2894
2895 if (result == this && phase->type(val)->is_zero_type()) {
2896 // the store may also apply to zero-bits in an earlier object
2897 Node* prev_mem = find_previous_store(phase);
2898 // Steps (a), (b): Walk past independent stores to find an exact match.
2899 if (prev_mem != nullptr) {
2900 Node* prev_val = can_see_stored_value(prev_mem, phase);
2901 if (prev_val != nullptr && prev_val == val) {
2902 // prev_val and val might differ by a cast; it would be good
2903 // to keep the more informative of the two.
2904 result = mem;
2905 }
2906 }
2907 }
2908 }
2909
2910 PhaseIterGVN* igvn = phase->is_IterGVN();
2911 if (result != this && igvn != nullptr) {
2912 MemBarNode* trailing = trailing_membar();
2913 if (trailing != nullptr) {
2914 #ifdef ASSERT
2915 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2916 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
2917 #endif
2918 trailing->remove(igvn);
2919 }
2920 }
2921
2922 return result;
2923 }
2924
2925 //------------------------------match_edge-------------------------------------
2926 // Do we Match on this edge index or not? Match only memory & value
2927 uint StoreNode::match_edge(uint idx) const {
2928 return idx == MemNode::Address || idx == MemNode::ValueIn;
2929 }
2930
2931 //------------------------------cmp--------------------------------------------
2932 // Do not common stores up together. They generally have to be split
2933 // back up anyways, so do not bother.
2934 bool StoreNode::cmp( const Node &n ) const {
2935 return (&n == this); // Always fail except on self
2936 }
2937
2938 //------------------------------Ideal_masked_input-----------------------------
2939 // Check for a useless mask before a partial-word store
2940 // (StoreB ... (AndI valIn conIa) )
2941 // If (conIa & mask == mask) this simplifies to
2942 // (StoreB ... (valIn) )
2943 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2944 Node *val = in(MemNode::ValueIn);
2945 if( val->Opcode() == Op_AndI ) {
2946 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2947 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2948 set_req_X(MemNode::ValueIn, val->in(1), phase);
2949 return this;
2950 }
2951 }
2952 return nullptr;
2953 }
2954
2955
2956 //------------------------------Ideal_sign_extended_input----------------------
2957 // Check for useless sign-extension before a partial-word store
2958 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2959 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2960 // (StoreB ... (valIn) )
2961 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2962 Node *val = in(MemNode::ValueIn);
2963 if( val->Opcode() == Op_RShiftI ) {
2964 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2965 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2966 Node *shl = val->in(1);
2967 if( shl->Opcode() == Op_LShiftI ) {
2968 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2969 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2970 set_req_X(MemNode::ValueIn, shl->in(1), phase);
2971 return this;
2972 }
2973 }
2974 }
2975 }
2976 return nullptr;
2977 }
2978
2979 //------------------------------value_never_loaded-----------------------------------
2980 // Determine whether there are any possible loads of the value stored.
2981 // For simplicity, we actually check if there are any loads from the
2982 // address stored to, not just for loads of the value stored by this node.
2983 //
2984 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
2985 Node *adr = in(Address);
2986 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2987 if (adr_oop == nullptr)
2988 return false;
2989 if (!adr_oop->is_known_instance_field())
2990 return false; // if not a distinct instance, there may be aliases of the address
2991 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2992 Node *use = adr->fast_out(i);
2993 if (use->is_Load() || use->is_LoadStore()) {
2994 return false;
2995 }
2996 }
2997 return true;
2998 }
2999
3000 MemBarNode* StoreNode::trailing_membar() const {
3001 if (is_release()) {
3002 MemBarNode* trailing_mb = nullptr;
3003 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3004 Node* u = fast_out(i);
3005 if (u->is_MemBar()) {
3006 if (u->as_MemBar()->trailing_store()) {
3007 assert(u->Opcode() == Op_MemBarVolatile, "");
3008 assert(trailing_mb == nullptr, "only one");
3009 trailing_mb = u->as_MemBar();
3010 #ifdef ASSERT
3011 Node* leading = u->as_MemBar()->leading_membar();
3012 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3013 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3014 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3015 #endif
3016 } else {
3017 assert(u->as_MemBar()->standalone(), "");
3018 }
3019 }
3020 }
3021 return trailing_mb;
3022 }
3023 return nullptr;
3024 }
3025
3026
3027 //=============================================================================
3028 //------------------------------Ideal------------------------------------------
3029 // If the store is from an AND mask that leaves the low bits untouched, then
3030 // we can skip the AND operation. If the store is from a sign-extension
3031 // (a left shift, then right shift) we can skip both.
3032 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3033 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3034 if( progress != nullptr ) return progress;
3035
3036 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3037 if( progress != nullptr ) return progress;
3038
3039 // Finally check the default case
3040 return StoreNode::Ideal(phase, can_reshape);
3041 }
3042
3043 //=============================================================================
3044 //------------------------------Ideal------------------------------------------
3045 // If the store is from an AND mask that leaves the low bits untouched, then
3046 // we can skip the AND operation
3047 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3048 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3049 if( progress != nullptr ) return progress;
3050
3051 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3052 if( progress != nullptr ) return progress;
3053
3054 // Finally check the default case
3055 return StoreNode::Ideal(phase, can_reshape);
3056 }
3057
3058 //=============================================================================
3059 //------------------------------Identity---------------------------------------
3060 Node* StoreCMNode::Identity(PhaseGVN* phase) {
3061 // No need to card mark when storing a null ptr
3062 Node* my_store = in(MemNode::OopStore);
3063 if (my_store->is_Store()) {
3064 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
3065 if( t1 == TypePtr::NULL_PTR ) {
3066 return in(MemNode::Memory);
3067 }
3068 }
3069 return this;
3070 }
3071
3072 //=============================================================================
3073 //------------------------------Ideal---------------------------------------
3074 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
3075 Node* progress = StoreNode::Ideal(phase, can_reshape);
3076 if (progress != nullptr) return progress;
3077
3078 Node* my_store = in(MemNode::OopStore);
3079 if (my_store->is_MergeMem()) {
3080 if (oop_alias_idx() != phase->C->get_alias_index(TypeAryPtr::INLINES) ||
3081 phase->C->flat_accesses_share_alias()) {
3082 // The alias that was recorded is no longer accurate enough.
3083 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
3084 set_req_X(MemNode::OopStore, mem, phase);
3085 return this;
3086 }
3087 }
3088
3089 return nullptr;
3090 }
3091
3092 //------------------------------Value-----------------------------------------
3093 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
3094 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
3095 // If extra input is TOP ==> the result is TOP
3096 const Type* t = phase->type(in(MemNode::OopStore));
3097 if (t == Type::TOP) {
3098 return Type::TOP;
3099 }
3100 return StoreNode::Value(phase);
3101 }
3102
3103
3104 //=============================================================================
3105 //----------------------------------SCMemProjNode------------------------------
3106 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3107 {
3108 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
3109 return Type::TOP;
3110 }
3111 return bottom_type();
3112 }
3113
3114 //=============================================================================
3115 //----------------------------------LoadStoreNode------------------------------
3116 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3117 : Node(required),
3118 _type(rt),
3119 _adr_type(at),
3120 _barrier_data(0)
3121 {
3122 init_req(MemNode::Control, c );
3123 init_req(MemNode::Memory , mem);
3124 init_req(MemNode::Address, adr);
3125 init_req(MemNode::ValueIn, val);
3126 init_class_id(Class_LoadStore);
3127 }
3128
3129 //------------------------------Value-----------------------------------------
3130 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3131 // Either input is TOP ==> the result is TOP
3132 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3133 return Type::TOP;
3134 }
3135 const Type* t = phase->type(in(MemNode::Memory));
3136 if (t == Type::TOP) {
3137 return Type::TOP;
3138 }
3139 t = phase->type(in(MemNode::Address));
3140 if (t == Type::TOP) {
3141 return Type::TOP;
3142 }
3143 t = phase->type(in(MemNode::ValueIn));
3144 if (t == Type::TOP) {
3145 return Type::TOP;
3146 }
3147 return bottom_type();
3148 }
3149
3150 uint LoadStoreNode::ideal_reg() const {
3151 return _type->ideal_reg();
3152 }
3153
3154 // This method conservatively checks if the result of a LoadStoreNode is
3155 // used, that is, if it returns true, then it is definitely the case that
3156 // the result of the node is not needed.
3157 // For example, GetAndAdd can be matched into a lock_add instead of a
3158 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
3159 bool LoadStoreNode::result_not_used() const {
3160 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3161 Node *x = fast_out(i);
3162 if (x->Opcode() == Op_SCMemProj) {
3163 continue;
3164 }
3165 if (x->bottom_type() == TypeTuple::MEMBAR &&
3166 !x->is_Call() &&
3167 x->Opcode() != Op_Blackhole) {
3168 continue;
3169 }
3170 return false;
3171 }
3172 return true;
3173 }
3174
3175 MemBarNode* LoadStoreNode::trailing_membar() const {
3176 MemBarNode* trailing = nullptr;
3177 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3178 Node* u = fast_out(i);
3179 if (u->is_MemBar()) {
3180 if (u->as_MemBar()->trailing_load_store()) {
3181 assert(u->Opcode() == Op_MemBarAcquire, "");
3182 assert(trailing == nullptr, "only one");
3183 trailing = u->as_MemBar();
3184 #ifdef ASSERT
3185 Node* leading = trailing->leading_membar();
3186 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3187 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3188 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3189 #endif
3190 } else {
3191 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3192 }
3193 }
3194 }
3195
3196 return trailing;
3197 }
3198
3199 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3200
3201 //=============================================================================
3202 //----------------------------------LoadStoreConditionalNode--------------------
3203 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
3204 init_req(ExpectedIn, ex );
3205 }
3206
3207 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3208 // Either input is TOP ==> the result is TOP
3209 const Type* t = phase->type(in(ExpectedIn));
3210 if (t == Type::TOP) {
3211 return Type::TOP;
3212 }
3213 return LoadStoreNode::Value(phase);
3214 }
3215
3216 //=============================================================================
3217 //-------------------------------adr_type--------------------------------------
3218 const TypePtr* ClearArrayNode::adr_type() const {
3219 Node *adr = in(3);
3220 if (adr == nullptr) return nullptr; // node is dead
3221 return MemNode::calculate_adr_type(adr->bottom_type());
3222 }
3223
3224 //------------------------------match_edge-------------------------------------
3225 // Do we Match on this edge index or not? Do not match memory
3226 uint ClearArrayNode::match_edge(uint idx) const {
3227 return idx > 1;
3228 }
3229
3230 //------------------------------Identity---------------------------------------
3231 // Clearing a zero length array does nothing
3232 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3233 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3234 }
3235
3236 //------------------------------Idealize---------------------------------------
3237 // Clearing a short array is faster with stores
3238 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3239 // Already know this is a large node, do not try to ideal it
3240 if (_is_large) return nullptr;
3241
3242 const int unit = BytesPerLong;
3243 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3244 if (!t) return nullptr;
3245 if (!t->is_con()) return nullptr;
3246 intptr_t raw_count = t->get_con();
3247 intptr_t size = raw_count;
3248 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3249 // Clearing nothing uses the Identity call.
3250 // Negative clears are possible on dead ClearArrays
3251 // (see jck test stmt114.stmt11402.val).
3252 if (size <= 0 || size % unit != 0) return nullptr;
3253 intptr_t count = size / unit;
3254 // Length too long; communicate this to matchers and assemblers.
3255 // Assemblers are responsible to produce fast hardware clears for it.
3256 if (size > InitArrayShortSize) {
3257 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
3258 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3259 return nullptr;
3260 }
3261 if (!IdealizeClearArrayNode) return nullptr;
3262 Node *mem = in(1);
3263 if( phase->type(mem)==Type::TOP ) return nullptr;
3264 Node *adr = in(3);
3265 const Type* at = phase->type(adr);
3266 if( at==Type::TOP ) return nullptr;
3267 const TypePtr* atp = at->isa_ptr();
3268 // adjust atp to be the correct array element address type
3269 if (atp == nullptr) atp = TypePtr::BOTTOM;
3270 else atp = atp->add_offset(Type::OffsetBot);
3271 // Get base for derived pointer purposes
3272 if( adr->Opcode() != Op_AddP ) Unimplemented();
3273 Node *base = adr->in(1);
3274
3275 Node *val = in(4);
3276 Node *off = phase->MakeConX(BytesPerLong);
3277 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3278 count--;
3279 while( count-- ) {
3280 mem = phase->transform(mem);
3281 adr = phase->transform(new AddPNode(base,adr,off));
3282 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3283 }
3284 return mem;
3285 }
3286
3287 //----------------------------step_through----------------------------------
3288 // Return allocation input memory edge if it is different instance
3289 // or itself if it is the one we are looking for.
3290 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
3291 Node* n = *np;
3292 assert(n->is_ClearArray(), "sanity");
3293 intptr_t offset;
3294 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3295 // This method is called only before Allocate nodes are expanded
3296 // during macro nodes expansion. Before that ClearArray nodes are
3297 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3298 // Allocate nodes are expanded) which follows allocations.
3299 assert(alloc != nullptr, "should have allocation");
3300 if (alloc->_idx == instance_id) {
3301 // Can not bypass initialization of the instance we are looking for.
3302 return false;
3303 }
3304 // Otherwise skip it.
3305 InitializeNode* init = alloc->initialization();
3306 if (init != nullptr)
3307 *np = init->in(TypeFunc::Memory);
3308 else
3309 *np = alloc->in(TypeFunc::Memory);
3310 return true;
3311 }
3312
3313 //----------------------------clear_memory-------------------------------------
3314 // Generate code to initialize object storage to zero.
3315 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3316 Node* val,
3317 Node* raw_val,
3318 intptr_t start_offset,
3319 Node* end_offset,
3320 PhaseGVN* phase) {
3321 intptr_t offset = start_offset;
3322
3323 int unit = BytesPerLong;
3324 if ((offset % unit) != 0) {
3325 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3326 adr = phase->transform(adr);
3327 const TypePtr* atp = TypeRawPtr::BOTTOM;
3328 if (val != nullptr) {
3329 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3330 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3331 } else {
3332 assert(raw_val == nullptr, "val may not be null");
3333 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3334 }
3335 mem = phase->transform(mem);
3336 offset += BytesPerInt;
3337 }
3338 assert((offset % unit) == 0, "");
3339
3340 // Initialize the remaining stuff, if any, with a ClearArray.
3341 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3342 }
3343
3344 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3345 Node* raw_val,
3346 Node* start_offset,
3347 Node* end_offset,
3348 PhaseGVN* phase) {
3349 if (start_offset == end_offset) {
3350 // nothing to do
3351 return mem;
3352 }
3353
3354 int unit = BytesPerLong;
3355 Node* zbase = start_offset;
3356 Node* zend = end_offset;
3357
3358 // Scale to the unit required by the CPU:
3359 if (!Matcher::init_array_count_is_in_bytes) {
3360 Node* shift = phase->intcon(exact_log2(unit));
3361 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3362 zend = phase->transform(new URShiftXNode(zend, shift) );
3363 }
3364
3365 // Bulk clear double-words
3366 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3367 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3368 if (raw_val == nullptr) {
3369 raw_val = phase->MakeConX(0);
3370 }
3371 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3372 return phase->transform(mem);
3373 }
3374
3375 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3376 Node* val,
3377 Node* raw_val,
3378 intptr_t start_offset,
3379 intptr_t end_offset,
3380 PhaseGVN* phase) {
3381 if (start_offset == end_offset) {
3382 // nothing to do
3383 return mem;
3384 }
3385
3386 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3387 intptr_t done_offset = end_offset;
3388 if ((done_offset % BytesPerLong) != 0) {
3389 done_offset -= BytesPerInt;
3390 }
3391 if (done_offset > start_offset) {
3392 mem = clear_memory(ctl, mem, dest, val, raw_val,
3393 start_offset, phase->MakeConX(done_offset), phase);
3394 }
3395 if (done_offset < end_offset) { // emit the final 32-bit store
3396 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3397 adr = phase->transform(adr);
3398 const TypePtr* atp = TypeRawPtr::BOTTOM;
3399 if (val != nullptr) {
3400 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3401 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3402 } else {
3403 assert(raw_val == nullptr, "val may not be null");
3404 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3405 }
3406 mem = phase->transform(mem);
3407 done_offset += BytesPerInt;
3408 }
3409 assert(done_offset == end_offset, "");
3410 return mem;
3411 }
3412
3413 //=============================================================================
3414 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3415 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
3416 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3417 #ifdef ASSERT
3418 , _pair_idx(0)
3419 #endif
3420 {
3421 init_class_id(Class_MemBar);
3422 Node* top = C->top();
3423 init_req(TypeFunc::I_O,top);
3424 init_req(TypeFunc::FramePtr,top);
3425 init_req(TypeFunc::ReturnAdr,top);
3426 if (precedent != nullptr)
3427 init_req(TypeFunc::Parms, precedent);
3428 }
3429
3430 //------------------------------cmp--------------------------------------------
3431 uint MemBarNode::hash() const { return NO_HASH; }
3432 bool MemBarNode::cmp( const Node &n ) const {
3433 return (&n == this); // Always fail except on self
3434 }
3435
3436 //------------------------------make-------------------------------------------
3437 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3438 switch (opcode) {
3439 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3440 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3441 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3442 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3443 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3444 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
3445 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3446 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3447 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3448 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3449 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3450 case Op_Initialize: return new InitializeNode(C, atp, pn);
3451 default: ShouldNotReachHere(); return nullptr;
3452 }
3453 }
3454
3455 void MemBarNode::remove(PhaseIterGVN *igvn) {
3456 if (outcnt() != 2) {
3457 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3458 assert(outcnt() == 1, "Only control then");
3459 }
3460 if (trailing_store() || trailing_load_store()) {
3461 MemBarNode* leading = leading_membar();
3462 if (leading != nullptr) {
3463 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3464 leading->remove(igvn);
3465 }
3466 }
3467 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
3468 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3469 }
3470 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
3471 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3472 }
3473 }
3474
3475 //------------------------------Ideal------------------------------------------
3476 // Return a node which is more "ideal" than the current node. Strip out
3477 // control copies
3478 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3479 if (remove_dead_region(phase, can_reshape)) return this;
3480 // Don't bother trying to transform a dead node
3481 if (in(0) && in(0)->is_top()) {
3482 return nullptr;
3483 }
3484
3485 bool progress = false;
3486 // Eliminate volatile MemBars for scalar replaced objects.
3487 if (can_reshape && req() == (Precedent+1)) {
3488 bool eliminate = false;
3489 int opc = Opcode();
3490 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3491 // Volatile field loads and stores.
3492 Node* my_mem = in(MemBarNode::Precedent);
3493 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3494 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3495 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3496 // replace this Precedent (decodeN) with the Load instead.
3497 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3498 Node* load_node = my_mem->in(1);
3499 set_req(MemBarNode::Precedent, load_node);
3500 phase->is_IterGVN()->_worklist.push(my_mem);
3501 my_mem = load_node;
3502 } else {
3503 assert(my_mem->unique_out() == this, "sanity");
3504 del_req(Precedent);
3505 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3506 my_mem = nullptr;
3507 }
3508 progress = true;
3509 }
3510 if (my_mem != nullptr && my_mem->is_Mem()) {
3511 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3512 // Check for scalar replaced object reference.
3513 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
3514 t_oop->offset() != Type::OffsetBot &&
3515 t_oop->offset() != Type::OffsetTop) {
3516 eliminate = true;
3517 }
3518 }
3519 } else if (opc == Op_MemBarRelease) {
3520 // Final field stores.
3521 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
3522 if ((alloc != nullptr) && alloc->is_Allocate() &&
3523 alloc->as_Allocate()->does_not_escape_thread()) {
3524 // The allocated object does not escape.
3525 eliminate = true;
3526 }
3527 }
3528 if (eliminate) {
3529 // Replace MemBar projections by its inputs.
3530 PhaseIterGVN* igvn = phase->is_IterGVN();
3531 remove(igvn);
3532 // Must return either the original node (now dead) or a new node
3533 // (Do not return a top here, since that would break the uniqueness of top.)
3534 return new ConINode(TypeInt::ZERO);
3535 }
3536 }
3537 return progress ? this : nullptr;
3538 }
3539
3540 //------------------------------Value------------------------------------------
3541 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3542 if( !in(0) ) return Type::TOP;
3543 if( phase->type(in(0)) == Type::TOP )
3544 return Type::TOP;
3545 return TypeTuple::MEMBAR;
3546 }
3547
3548 //------------------------------match------------------------------------------
3549 // Construct projections for memory.
3550 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3551 switch (proj->_con) {
3552 case TypeFunc::Control:
3553 case TypeFunc::Memory:
3554 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3555 }
3556 ShouldNotReachHere();
3557 return nullptr;
3558 }
3559
3560 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3561 trailing->_kind = TrailingStore;
3562 leading->_kind = LeadingStore;
3563 #ifdef ASSERT
3564 trailing->_pair_idx = leading->_idx;
3565 leading->_pair_idx = leading->_idx;
3566 #endif
3567 }
3568
3569 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3570 trailing->_kind = TrailingLoadStore;
3571 leading->_kind = LeadingLoadStore;
3572 #ifdef ASSERT
3573 trailing->_pair_idx = leading->_idx;
3574 leading->_pair_idx = leading->_idx;
3575 #endif
3576 }
3577
3578 MemBarNode* MemBarNode::trailing_membar() const {
3579 ResourceMark rm;
3580 Node* trailing = (Node*)this;
3581 VectorSet seen;
3582 Node_Stack multis(0);
3583 do {
3584 Node* c = trailing;
3585 uint i = 0;
3586 do {
3587 trailing = nullptr;
3588 for (; i < c->outcnt(); i++) {
3589 Node* next = c->raw_out(i);
3590 if (next != c && next->is_CFG()) {
3591 if (c->is_MultiBranch()) {
3592 if (multis.node() == c) {
3593 multis.set_index(i+1);
3594 } else {
3595 multis.push(c, i+1);
3596 }
3597 }
3598 trailing = next;
3599 break;
3600 }
3601 }
3602 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
3603 break;
3604 }
3605 while (multis.size() > 0) {
3606 c = multis.node();
3607 i = multis.index();
3608 if (i < c->req()) {
3609 break;
3610 }
3611 multis.pop();
3612 }
3613 } while (multis.size() > 0);
3614 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3615
3616 MemBarNode* mb = trailing->as_MemBar();
3617 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3618 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3619 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3620 return mb;
3621 }
3622
3623 MemBarNode* MemBarNode::leading_membar() const {
3624 ResourceMark rm;
3625 VectorSet seen;
3626 Node_Stack regions(0);
3627 Node* leading = in(0);
3628 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3629 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
3630 leading = nullptr;
3631 while (regions.size() > 0 && leading == nullptr) {
3632 Node* r = regions.node();
3633 uint i = regions.index();
3634 if (i < r->req()) {
3635 leading = r->in(i);
3636 regions.set_index(i+1);
3637 } else {
3638 regions.pop();
3639 }
3640 }
3641 if (leading == nullptr) {
3642 assert(regions.size() == 0, "all paths should have been tried");
3643 return nullptr;
3644 }
3645 }
3646 if (leading->is_Region()) {
3647 regions.push(leading, 2);
3648 leading = leading->in(1);
3649 } else {
3650 leading = leading->in(0);
3651 }
3652 }
3653 #ifdef ASSERT
3654 Unique_Node_List wq;
3655 wq.push((Node*)this);
3656 uint found = 0;
3657 for (uint i = 0; i < wq.size(); i++) {
3658 Node* n = wq.at(i);
3659 if (n->is_Region()) {
3660 for (uint j = 1; j < n->req(); j++) {
3661 Node* in = n->in(j);
3662 if (in != nullptr && !in->is_top()) {
3663 wq.push(in);
3664 }
3665 }
3666 } else {
3667 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3668 assert(n == leading, "consistency check failed");
3669 found++;
3670 } else {
3671 Node* in = n->in(0);
3672 if (in != nullptr && !in->is_top()) {
3673 wq.push(in);
3674 }
3675 }
3676 }
3677 }
3678 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
3679 #endif
3680 if (leading == nullptr) {
3681 return nullptr;
3682 }
3683 MemBarNode* mb = leading->as_MemBar();
3684 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3685 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3686 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3687 return mb;
3688 }
3689
3690
3691 //===========================InitializeNode====================================
3692 // SUMMARY:
3693 // This node acts as a memory barrier on raw memory, after some raw stores.
3694 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3695 // The Initialize can 'capture' suitably constrained stores as raw inits.
3696 // It can coalesce related raw stores into larger units (called 'tiles').
3697 // It can avoid zeroing new storage for memory units which have raw inits.
3698 // At macro-expansion, it is marked 'complete', and does not optimize further.
3699 //
3700 // EXAMPLE:
3701 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3702 // ctl = incoming control; mem* = incoming memory
3703 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3704 // First allocate uninitialized memory and fill in the header:
3705 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3706 // ctl := alloc.Control; mem* := alloc.Memory*
3707 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3708 // Then initialize to zero the non-header parts of the raw memory block:
3709 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3710 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3711 // After the initialize node executes, the object is ready for service:
3712 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3713 // Suppose its body is immediately initialized as {1,2}:
3714 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3715 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3716 // mem.SLICE(#short[*]) := store2
3717 //
3718 // DETAILS:
3719 // An InitializeNode collects and isolates object initialization after
3720 // an AllocateNode and before the next possible safepoint. As a
3721 // memory barrier (MemBarNode), it keeps critical stores from drifting
3722 // down past any safepoint or any publication of the allocation.
3723 // Before this barrier, a newly-allocated object may have uninitialized bits.
3724 // After this barrier, it may be treated as a real oop, and GC is allowed.
3725 //
3726 // The semantics of the InitializeNode include an implicit zeroing of
3727 // the new object from object header to the end of the object.
3728 // (The object header and end are determined by the AllocateNode.)
3729 //
3730 // Certain stores may be added as direct inputs to the InitializeNode.
3731 // These stores must update raw memory, and they must be to addresses
3732 // derived from the raw address produced by AllocateNode, and with
3733 // a constant offset. They must be ordered by increasing offset.
3734 // The first one is at in(RawStores), the last at in(req()-1).
3735 // Unlike most memory operations, they are not linked in a chain,
3736 // but are displayed in parallel as users of the rawmem output of
3737 // the allocation.
3738 //
3739 // (See comments in InitializeNode::capture_store, which continue
3740 // the example given above.)
3741 //
3742 // When the associated Allocate is macro-expanded, the InitializeNode
3743 // may be rewritten to optimize collected stores. A ClearArrayNode
3744 // may also be created at that point to represent any required zeroing.
3745 // The InitializeNode is then marked 'complete', prohibiting further
3746 // capturing of nearby memory operations.
3747 //
3748 // During macro-expansion, all captured initializations which store
3749 // constant values of 32 bits or smaller are coalesced (if advantageous)
3750 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3751 // initialized in fewer memory operations. Memory words which are
3752 // covered by neither tiles nor non-constant stores are pre-zeroed
3753 // by explicit stores of zero. (The code shape happens to do all
3754 // zeroing first, then all other stores, with both sequences occurring
3755 // in order of ascending offsets.)
3756 //
3757 // Alternatively, code may be inserted between an AllocateNode and its
3758 // InitializeNode, to perform arbitrary initialization of the new object.
3759 // E.g., the object copying intrinsics insert complex data transfers here.
3760 // The initialization must then be marked as 'complete' disable the
3761 // built-in zeroing semantics and the collection of initializing stores.
3762 //
3763 // While an InitializeNode is incomplete, reads from the memory state
3764 // produced by it are optimizable if they match the control edge and
3765 // new oop address associated with the allocation/initialization.
3766 // They return a stored value (if the offset matches) or else zero.
3767 // A write to the memory state, if it matches control and address,
3768 // and if it is to a constant offset, may be 'captured' by the
3769 // InitializeNode. It is cloned as a raw memory operation and rewired
3770 // inside the initialization, to the raw oop produced by the allocation.
3771 // Operations on addresses which are provably distinct (e.g., to
3772 // other AllocateNodes) are allowed to bypass the initialization.
3773 //
3774 // The effect of all this is to consolidate object initialization
3775 // (both arrays and non-arrays, both piecewise and bulk) into a
3776 // single location, where it can be optimized as a unit.
3777 //
3778 // Only stores with an offset less than TrackedInitializationLimit words
3779 // will be considered for capture by an InitializeNode. This puts a
3780 // reasonable limit on the complexity of optimized initializations.
3781
3782 //---------------------------InitializeNode------------------------------------
3783 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3784 : MemBarNode(C, adr_type, rawoop),
3785 _is_complete(Incomplete), _does_not_escape(false)
3786 {
3787 init_class_id(Class_Initialize);
3788
3789 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3790 assert(in(RawAddress) == rawoop, "proper init");
3791 // Note: allocation() can be null, for secondary initialization barriers
3792 }
3793
3794 // Since this node is not matched, it will be processed by the
3795 // register allocator. Declare that there are no constraints
3796 // on the allocation of the RawAddress edge.
3797 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3798 // This edge should be set to top, by the set_complete. But be conservative.
3799 if (idx == InitializeNode::RawAddress)
3800 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3801 return RegMask::Empty;
3802 }
3803
3804 Node* InitializeNode::memory(uint alias_idx) {
3805 Node* mem = in(Memory);
3806 if (mem->is_MergeMem()) {
3807 return mem->as_MergeMem()->memory_at(alias_idx);
3808 } else {
3809 // incoming raw memory is not split
3810 return mem;
3811 }
3812 }
3813
3814 bool InitializeNode::is_non_zero() {
3815 if (is_complete()) return false;
3816 remove_extra_zeroes();
3817 return (req() > RawStores);
3818 }
3819
3820 void InitializeNode::set_complete(PhaseGVN* phase) {
3821 assert(!is_complete(), "caller responsibility");
3822 _is_complete = Complete;
3823
3824 // After this node is complete, it contains a bunch of
3825 // raw-memory initializations. There is no need for
3826 // it to have anything to do with non-raw memory effects.
3827 // Therefore, tell all non-raw users to re-optimize themselves,
3828 // after skipping the memory effects of this initialization.
3829 PhaseIterGVN* igvn = phase->is_IterGVN();
3830 if (igvn) igvn->add_users_to_worklist(this);
3831 }
3832
3833 // convenience function
3834 // return false if the init contains any stores already
3835 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3836 InitializeNode* init = initialization();
3837 if (init == nullptr || init->is_complete()) {
3838 return false;
3839 }
3840 init->remove_extra_zeroes();
3841 // for now, if this allocation has already collected any inits, bail:
3842 if (init->is_non_zero()) return false;
3843 init->set_complete(phase);
3844 return true;
3845 }
3846
3847 void InitializeNode::remove_extra_zeroes() {
3848 if (req() == RawStores) return;
3849 Node* zmem = zero_memory();
3850 uint fill = RawStores;
3851 for (uint i = fill; i < req(); i++) {
3852 Node* n = in(i);
3853 if (n->is_top() || n == zmem) continue; // skip
3854 if (fill < i) set_req(fill, n); // compact
3855 ++fill;
3856 }
3857 // delete any empty spaces created:
3858 while (fill < req()) {
3859 del_req(fill);
3860 }
3861 }
3862
3863 // Helper for remembering which stores go with which offsets.
3864 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
3865 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3866 intptr_t offset = -1;
3867 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3868 phase, offset);
3869 if (base == nullptr) return -1; // something is dead,
3870 if (offset < 0) return -1; // dead, dead
3871 return offset;
3872 }
3873
3874 // Helper for proving that an initialization expression is
3875 // "simple enough" to be folded into an object initialization.
3876 // Attempts to prove that a store's initial value 'n' can be captured
3877 // within the initialization without creating a vicious cycle, such as:
3878 // { Foo p = new Foo(); p.next = p; }
3879 // True for constants and parameters and small combinations thereof.
3880 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3881 ResourceMark rm;
3882 Unique_Node_List worklist;
3883 worklist.push(value);
3884
3885 uint complexity_limit = 20;
3886 for (uint j = 0; j < worklist.size(); j++) {
3887 if (j >= complexity_limit) {
3888 return false; // Bail out if processed too many nodes
3889 }
3890
3891 Node* n = worklist.at(j);
3892 if (n == nullptr) continue; // (can this really happen?)
3893 if (n->is_Proj()) n = n->in(0);
3894 if (n == this) return false; // found a cycle
3895 if (n->is_Con()) continue;
3896 if (n->is_Start()) continue; // params, etc., are OK
3897 if (n->is_Root()) continue; // even better
3898
3899 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3900 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3901 continue;
3902 }
3903
3904 Node* ctl = n->in(0);
3905 if (ctl != nullptr && !ctl->is_top()) {
3906 if (ctl->is_Proj()) ctl = ctl->in(0);
3907 if (ctl == this) return false;
3908
3909 // If we already know that the enclosing memory op is pinned right after
3910 // the init, then any control flow that the store has picked up
3911 // must have preceded the init, or else be equal to the init.
3912 // Even after loop optimizations (which might change control edges)
3913 // a store is never pinned *before* the availability of its inputs.
3914 if (!MemNode::all_controls_dominate(n, this))
3915 return false; // failed to prove a good control
3916 }
3917
3918 // Check data edges for possible dependencies on 'this'.
3919 for (uint i = 1; i < n->req(); i++) {
3920 Node* m = n->in(i);
3921 if (m == nullptr || m == n || m->is_top()) continue;
3922
3923 // Only process data inputs once
3924 worklist.push(m);
3925 }
3926 }
3927
3928 return true;
3929 }
3930
3931 // Here are all the checks a Store must pass before it can be moved into
3932 // an initialization. Returns zero if a check fails.
3933 // On success, returns the (constant) offset to which the store applies,
3934 // within the initialized memory.
3935 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3936 const int FAIL = 0;
3937 if (st->req() != MemNode::ValueIn + 1)
3938 return FAIL; // an inscrutable StoreNode (card mark?)
3939 Node* ctl = st->in(MemNode::Control);
3940 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
3941 return FAIL; // must be unconditional after the initialization
3942 Node* mem = st->in(MemNode::Memory);
3943 if (!(mem->is_Proj() && mem->in(0) == this))
3944 return FAIL; // must not be preceded by other stores
3945 Node* adr = st->in(MemNode::Address);
3946 intptr_t offset;
3947 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3948 if (alloc == nullptr)
3949 return FAIL; // inscrutable address
3950 if (alloc != allocation())
3951 return FAIL; // wrong allocation! (store needs to float up)
3952 int size_in_bytes = st->memory_size();
3953 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3954 return FAIL; // mismatched access
3955 }
3956 Node* val = st->in(MemNode::ValueIn);
3957
3958 if (!detect_init_independence(val, phase))
3959 return FAIL; // stored value must be 'simple enough'
3960
3961 // The Store can be captured only if nothing after the allocation
3962 // and before the Store is using the memory location that the store
3963 // overwrites.
3964 bool failed = false;
3965 // If is_complete_with_arraycopy() is true the shape of the graph is
3966 // well defined and is safe so no need for extra checks.
3967 if (!is_complete_with_arraycopy()) {
3968 // We are going to look at each use of the memory state following
3969 // the allocation to make sure nothing reads the memory that the
3970 // Store writes.
3971 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3972 int alias_idx = phase->C->get_alias_index(t_adr);
3973 ResourceMark rm;
3974 Unique_Node_List mems;
3975 mems.push(mem);
3976 Node* unique_merge = nullptr;
3977 for (uint next = 0; next < mems.size(); ++next) {
3978 Node *m = mems.at(next);
3979 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3980 Node *n = m->fast_out(j);
3981 if (n->outcnt() == 0) {
3982 continue;
3983 }
3984 if (n == st) {
3985 continue;
3986 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
3987 // If the control of this use is different from the control
3988 // of the Store which is right after the InitializeNode then
3989 // this node cannot be between the InitializeNode and the
3990 // Store.
3991 continue;
3992 } else if (n->is_MergeMem()) {
3993 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3994 // We can hit a MergeMemNode (that will likely go away
3995 // later) that is a direct use of the memory state
3996 // following the InitializeNode on the same slice as the
3997 // store node that we'd like to capture. We need to check
3998 // the uses of the MergeMemNode.
3999 mems.push(n);
4000 }
4001 } else if (n->is_Mem()) {
4002 Node* other_adr = n->in(MemNode::Address);
4003 if (other_adr == adr) {
4004 failed = true;
4005 break;
4006 } else {
4007 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4008 if (other_t_adr != nullptr) {
4009 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4010 if (other_alias_idx == alias_idx) {
4011 // A load from the same memory slice as the store right
4012 // after the InitializeNode. We check the control of the
4013 // object/array that is loaded from. If it's the same as
4014 // the store control then we cannot capture the store.
4015 assert(!n->is_Store(), "2 stores to same slice on same control?");
4016 Node* base = other_adr;
4017 if (base->is_Phi()) {
4018 // In rare case, base may be a PhiNode and it may read
4019 // the same memory slice between InitializeNode and store.
4020 failed = true;
4021 break;
4022 }
4023 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4024 base = base->in(AddPNode::Base);
4025 if (base != nullptr) {
4026 base = base->uncast();
4027 if (base->is_Proj() && base->in(0) == alloc) {
4028 failed = true;
4029 break;
4030 }
4031 }
4032 }
4033 }
4034 }
4035 } else {
4036 failed = true;
4037 break;
4038 }
4039 }
4040 }
4041 }
4042 if (failed) {
4043 if (!can_reshape) {
4044 // We decided we couldn't capture the store during parsing. We
4045 // should try again during the next IGVN once the graph is
4046 // cleaner.
4047 phase->C->record_for_igvn(st);
4048 }
4049 return FAIL;
4050 }
4051
4052 return offset; // success
4053 }
4054
4055 // Find the captured store in(i) which corresponds to the range
4056 // [start..start+size) in the initialized object.
4057 // If there is one, return its index i. If there isn't, return the
4058 // negative of the index where it should be inserted.
4059 // Return 0 if the queried range overlaps an initialization boundary
4060 // or if dead code is encountered.
4061 // If size_in_bytes is zero, do not bother with overlap checks.
4062 int InitializeNode::captured_store_insertion_point(intptr_t start,
4063 int size_in_bytes,
4064 PhaseValues* phase) {
4065 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4066
4067 if (is_complete())
4068 return FAIL; // arraycopy got here first; punt
4069
4070 assert(allocation() != nullptr, "must be present");
4071
4072 // no negatives, no header fields:
4073 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
4074
4075 // after a certain size, we bail out on tracking all the stores:
4076 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4077 if (start >= ti_limit) return FAIL;
4078
4079 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4080 if (i >= limit) return -(int)i; // not found; here is where to put it
4081
4082 Node* st = in(i);
4083 intptr_t st_off = get_store_offset(st, phase);
4084 if (st_off < 0) {
4085 if (st != zero_memory()) {
4086 return FAIL; // bail out if there is dead garbage
4087 }
4088 } else if (st_off > start) {
4089 // ...we are done, since stores are ordered
4090 if (st_off < start + size_in_bytes) {
4091 return FAIL; // the next store overlaps
4092 }
4093 return -(int)i; // not found; here is where to put it
4094 } else if (st_off < start) {
4095 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4096 if (size_in_bytes != 0 &&
4097 start < st_off + MAX_STORE &&
4098 start < st_off + st->as_Store()->memory_size()) {
4099 return FAIL; // the previous store overlaps
4100 }
4101 } else {
4102 if (size_in_bytes != 0 &&
4103 st->as_Store()->memory_size() != size_in_bytes) {
4104 return FAIL; // mismatched store size
4105 }
4106 return i;
4107 }
4108
4109 ++i;
4110 }
4111 }
4112
4113 // Look for a captured store which initializes at the offset 'start'
4114 // with the given size. If there is no such store, and no other
4115 // initialization interferes, then return zero_memory (the memory
4116 // projection of the AllocateNode).
4117 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4118 PhaseValues* phase) {
4119 assert(stores_are_sane(phase), "");
4120 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4121 if (i == 0) {
4122 return nullptr; // something is dead
4123 } else if (i < 0) {
4124 return zero_memory(); // just primordial zero bits here
4125 } else {
4126 Node* st = in(i); // here is the store at this position
4127 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4128 return st;
4129 }
4130 }
4131
4132 // Create, as a raw pointer, an address within my new object at 'offset'.
4133 Node* InitializeNode::make_raw_address(intptr_t offset,
4134 PhaseGVN* phase) {
4135 Node* addr = in(RawAddress);
4136 if (offset != 0) {
4137 Compile* C = phase->C;
4138 addr = phase->transform( new AddPNode(C->top(), addr,
4139 phase->MakeConX(offset)) );
4140 }
4141 return addr;
4142 }
4143
4144 // Clone the given store, converting it into a raw store
4145 // initializing a field or element of my new object.
4146 // Caller is responsible for retiring the original store,
4147 // with subsume_node or the like.
4148 //
4149 // From the example above InitializeNode::InitializeNode,
4150 // here are the old stores to be captured:
4151 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4152 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4153 //
4154 // Here is the changed code; note the extra edges on init:
4155 // alloc = (Allocate ...)
4156 // rawoop = alloc.RawAddress
4157 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4158 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4159 // init = (Initialize alloc.Control alloc.Memory rawoop
4160 // rawstore1 rawstore2)
4161 //
4162 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4163 PhaseGVN* phase, bool can_reshape) {
4164 assert(stores_are_sane(phase), "");
4165
4166 if (start < 0) return nullptr;
4167 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4168
4169 Compile* C = phase->C;
4170 int size_in_bytes = st->memory_size();
4171 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4172 if (i == 0) return nullptr; // bail out
4173 Node* prev_mem = nullptr; // raw memory for the captured store
4174 if (i > 0) {
4175 prev_mem = in(i); // there is a pre-existing store under this one
4176 set_req(i, C->top()); // temporarily disconnect it
4177 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4178 } else {
4179 i = -i; // no pre-existing store
4180 prev_mem = zero_memory(); // a slice of the newly allocated object
4181 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4182 set_req(--i, C->top()); // reuse this edge; it has been folded away
4183 else
4184 ins_req(i, C->top()); // build a new edge
4185 }
4186 Node* new_st = st->clone();
4187 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4188 new_st->set_req(MemNode::Control, in(Control));
4189 new_st->set_req(MemNode::Memory, prev_mem);
4190 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4191 bs->eliminate_gc_barrier_data(new_st);
4192 new_st = phase->transform(new_st);
4193
4194 // At this point, new_st might have swallowed a pre-existing store
4195 // at the same offset, or perhaps new_st might have disappeared,
4196 // if it redundantly stored the same value (or zero to fresh memory).
4197
4198 // In any case, wire it in:
4199 PhaseIterGVN* igvn = phase->is_IterGVN();
4200 if (igvn) {
4201 igvn->rehash_node_delayed(this);
4202 }
4203 set_req(i, new_st);
4204
4205 // The caller may now kill the old guy.
4206 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4207 assert(check_st == new_st || check_st == nullptr, "must be findable");
4208 assert(!is_complete(), "");
4209 return new_st;
4210 }
4211
4212 static bool store_constant(jlong* tiles, int num_tiles,
4213 intptr_t st_off, int st_size,
4214 jlong con) {
4215 if ((st_off & (st_size-1)) != 0)
4216 return false; // strange store offset (assume size==2**N)
4217 address addr = (address)tiles + st_off;
4218 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4219 switch (st_size) {
4220 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4221 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4222 case sizeof(jint): *(jint*) addr = (jint) con; break;
4223 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4224 default: return false; // strange store size (detect size!=2**N here)
4225 }
4226 return true; // return success to caller
4227 }
4228
4229 // Coalesce subword constants into int constants and possibly
4230 // into long constants. The goal, if the CPU permits,
4231 // is to initialize the object with a small number of 64-bit tiles.
4232 // Also, convert floating-point constants to bit patterns.
4233 // Non-constants are not relevant to this pass.
4234 //
4235 // In terms of the running example on InitializeNode::InitializeNode
4236 // and InitializeNode::capture_store, here is the transformation
4237 // of rawstore1 and rawstore2 into rawstore12:
4238 // alloc = (Allocate ...)
4239 // rawoop = alloc.RawAddress
4240 // tile12 = 0x00010002
4241 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4242 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4243 //
4244 void
4245 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4246 Node* size_in_bytes,
4247 PhaseGVN* phase) {
4248 Compile* C = phase->C;
4249
4250 assert(stores_are_sane(phase), "");
4251 // Note: After this pass, they are not completely sane,
4252 // since there may be some overlaps.
4253
4254 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4255
4256 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4257 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4258 size_limit = MIN2(size_limit, ti_limit);
4259 size_limit = align_up(size_limit, BytesPerLong);
4260 int num_tiles = size_limit / BytesPerLong;
4261
4262 // allocate space for the tile map:
4263 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4264 jlong tiles_buf[small_len];
4265 Node* nodes_buf[small_len];
4266 jlong inits_buf[small_len];
4267 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4268 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4269 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4270 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4271 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4272 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4273 // tiles: exact bitwise model of all primitive constants
4274 // nodes: last constant-storing node subsumed into the tiles model
4275 // inits: which bytes (in each tile) are touched by any initializations
4276
4277 //// Pass A: Fill in the tile model with any relevant stores.
4278
4279 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4280 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4281 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4282 Node* zmem = zero_memory(); // initially zero memory state
4283 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4284 Node* st = in(i);
4285 intptr_t st_off = get_store_offset(st, phase);
4286
4287 // Figure out the store's offset and constant value:
4288 if (st_off < header_size) continue; //skip (ignore header)
4289 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4290 int st_size = st->as_Store()->memory_size();
4291 if (st_off + st_size > size_limit) break;
4292
4293 // Record which bytes are touched, whether by constant or not.
4294 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4295 continue; // skip (strange store size)
4296
4297 const Type* val = phase->type(st->in(MemNode::ValueIn));
4298 if (!val->singleton()) continue; //skip (non-con store)
4299 BasicType type = val->basic_type();
4300
4301 jlong con = 0;
4302 switch (type) {
4303 case T_INT: con = val->is_int()->get_con(); break;
4304 case T_LONG: con = val->is_long()->get_con(); break;
4305 case T_FLOAT: con = jint_cast(val->getf()); break;
4306 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4307 default: continue; //skip (odd store type)
4308 }
4309
4310 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4311 st->Opcode() == Op_StoreL) {
4312 continue; // This StoreL is already optimal.
4313 }
4314
4315 // Store down the constant.
4316 store_constant(tiles, num_tiles, st_off, st_size, con);
4317
4318 intptr_t j = st_off >> LogBytesPerLong;
4319
4320 if (type == T_INT && st_size == BytesPerInt
4321 && (st_off & BytesPerInt) == BytesPerInt) {
4322 jlong lcon = tiles[j];
4323 if (!Matcher::isSimpleConstant64(lcon) &&
4324 st->Opcode() == Op_StoreI) {
4325 // This StoreI is already optimal by itself.
4326 jint* intcon = (jint*) &tiles[j];
4327 intcon[1] = 0; // undo the store_constant()
4328
4329 // If the previous store is also optimal by itself, back up and
4330 // undo the action of the previous loop iteration... if we can.
4331 // But if we can't, just let the previous half take care of itself.
4332 st = nodes[j];
4333 st_off -= BytesPerInt;
4334 con = intcon[0];
4335 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
4336 assert(st_off >= header_size, "still ignoring header");
4337 assert(get_store_offset(st, phase) == st_off, "must be");
4338 assert(in(i-1) == zmem, "must be");
4339 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4340 assert(con == tcon->is_int()->get_con(), "must be");
4341 // Undo the effects of the previous loop trip, which swallowed st:
4342 intcon[0] = 0; // undo store_constant()
4343 set_req(i-1, st); // undo set_req(i, zmem)
4344 nodes[j] = nullptr; // undo nodes[j] = st
4345 --old_subword; // undo ++old_subword
4346 }
4347 continue; // This StoreI is already optimal.
4348 }
4349 }
4350
4351 // This store is not needed.
4352 set_req(i, zmem);
4353 nodes[j] = st; // record for the moment
4354 if (st_size < BytesPerLong) // something has changed
4355 ++old_subword; // includes int/float, but who's counting...
4356 else ++old_long;
4357 }
4358
4359 if ((old_subword + old_long) == 0)
4360 return; // nothing more to do
4361
4362 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4363 // Be sure to insert them before overlapping non-constant stores.
4364 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4365 for (int j = 0; j < num_tiles; j++) {
4366 jlong con = tiles[j];
4367 jlong init = inits[j];
4368 if (con == 0) continue;
4369 jint con0, con1; // split the constant, address-wise
4370 jint init0, init1; // split the init map, address-wise
4371 { union { jlong con; jint intcon[2]; } u;
4372 u.con = con;
4373 con0 = u.intcon[0];
4374 con1 = u.intcon[1];
4375 u.con = init;
4376 init0 = u.intcon[0];
4377 init1 = u.intcon[1];
4378 }
4379
4380 Node* old = nodes[j];
4381 assert(old != nullptr, "need the prior store");
4382 intptr_t offset = (j * BytesPerLong);
4383
4384 bool split = !Matcher::isSimpleConstant64(con);
4385
4386 if (offset < header_size) {
4387 assert(offset + BytesPerInt >= header_size, "second int counts");
4388 assert(*(jint*)&tiles[j] == 0, "junk in header");
4389 split = true; // only the second word counts
4390 // Example: int a[] = { 42 ... }
4391 } else if (con0 == 0 && init0 == -1) {
4392 split = true; // first word is covered by full inits
4393 // Example: int a[] = { ... foo(), 42 ... }
4394 } else if (con1 == 0 && init1 == -1) {
4395 split = true; // second word is covered by full inits
4396 // Example: int a[] = { ... 42, foo() ... }
4397 }
4398
4399 // Here's a case where init0 is neither 0 nor -1:
4400 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4401 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4402 // In this case the tile is not split; it is (jlong)42.
4403 // The big tile is stored down, and then the foo() value is inserted.
4404 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4405
4406 Node* ctl = old->in(MemNode::Control);
4407 Node* adr = make_raw_address(offset, phase);
4408 const TypePtr* atp = TypeRawPtr::BOTTOM;
4409
4410 // One or two coalesced stores to plop down.
4411 Node* st[2];
4412 intptr_t off[2];
4413 int nst = 0;
4414 if (!split) {
4415 ++new_long;
4416 off[nst] = offset;
4417 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4418 phase->longcon(con), T_LONG, MemNode::unordered);
4419 } else {
4420 // Omit either if it is a zero.
4421 if (con0 != 0) {
4422 ++new_int;
4423 off[nst] = offset;
4424 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4425 phase->intcon(con0), T_INT, MemNode::unordered);
4426 }
4427 if (con1 != 0) {
4428 ++new_int;
4429 offset += BytesPerInt;
4430 adr = make_raw_address(offset, phase);
4431 off[nst] = offset;
4432 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4433 phase->intcon(con1), T_INT, MemNode::unordered);
4434 }
4435 }
4436
4437 // Insert second store first, then the first before the second.
4438 // Insert each one just before any overlapping non-constant stores.
4439 while (nst > 0) {
4440 Node* st1 = st[--nst];
4441 C->copy_node_notes_to(st1, old);
4442 st1 = phase->transform(st1);
4443 offset = off[nst];
4444 assert(offset >= header_size, "do not smash header");
4445 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4446 guarantee(ins_idx != 0, "must re-insert constant store");
4447 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4448 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4449 set_req(--ins_idx, st1);
4450 else
4451 ins_req(ins_idx, st1);
4452 }
4453 }
4454
4455 if (PrintCompilation && WizardMode)
4456 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4457 old_subword, old_long, new_int, new_long);
4458 if (C->log() != nullptr)
4459 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4460 old_subword, old_long, new_int, new_long);
4461
4462 // Clean up any remaining occurrences of zmem:
4463 remove_extra_zeroes();
4464 }
4465
4466 // Explore forward from in(start) to find the first fully initialized
4467 // word, and return its offset. Skip groups of subword stores which
4468 // together initialize full words. If in(start) is itself part of a
4469 // fully initialized word, return the offset of in(start). If there
4470 // are no following full-word stores, or if something is fishy, return
4471 // a negative value.
4472 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4473 int int_map = 0;
4474 intptr_t int_map_off = 0;
4475 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4476
4477 for (uint i = start, limit = req(); i < limit; i++) {
4478 Node* st = in(i);
4479
4480 intptr_t st_off = get_store_offset(st, phase);
4481 if (st_off < 0) break; // return conservative answer
4482
4483 int st_size = st->as_Store()->memory_size();
4484 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4485 return st_off; // we found a complete word init
4486 }
4487
4488 // update the map:
4489
4490 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4491 if (this_int_off != int_map_off) {
4492 // reset the map:
4493 int_map = 0;
4494 int_map_off = this_int_off;
4495 }
4496
4497 int subword_off = st_off - this_int_off;
4498 int_map |= right_n_bits(st_size) << subword_off;
4499 if ((int_map & FULL_MAP) == FULL_MAP) {
4500 return this_int_off; // we found a complete word init
4501 }
4502
4503 // Did this store hit or cross the word boundary?
4504 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4505 if (next_int_off == this_int_off + BytesPerInt) {
4506 // We passed the current int, without fully initializing it.
4507 int_map_off = next_int_off;
4508 int_map >>= BytesPerInt;
4509 } else if (next_int_off > this_int_off + BytesPerInt) {
4510 // We passed the current and next int.
4511 return this_int_off + BytesPerInt;
4512 }
4513 }
4514
4515 return -1;
4516 }
4517
4518
4519 // Called when the associated AllocateNode is expanded into CFG.
4520 // At this point, we may perform additional optimizations.
4521 // Linearize the stores by ascending offset, to make memory
4522 // activity as coherent as possible.
4523 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4524 intptr_t header_size,
4525 Node* size_in_bytes,
4526 PhaseIterGVN* phase) {
4527 assert(!is_complete(), "not already complete");
4528 assert(stores_are_sane(phase), "");
4529 assert(allocation() != nullptr, "must be present");
4530
4531 remove_extra_zeroes();
4532
4533 if (ReduceFieldZeroing || ReduceBulkZeroing)
4534 // reduce instruction count for common initialization patterns
4535 coalesce_subword_stores(header_size, size_in_bytes, phase);
4536
4537 Node* zmem = zero_memory(); // initially zero memory state
4538 Node* inits = zmem; // accumulating a linearized chain of inits
4539 #ifdef ASSERT
4540 intptr_t first_offset = allocation()->minimum_header_size();
4541 intptr_t last_init_off = first_offset; // previous init offset
4542 intptr_t last_init_end = first_offset; // previous init offset+size
4543 intptr_t last_tile_end = first_offset; // previous tile offset+size
4544 #endif
4545 intptr_t zeroes_done = header_size;
4546
4547 bool do_zeroing = true; // we might give up if inits are very sparse
4548 int big_init_gaps = 0; // how many large gaps have we seen?
4549
4550 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4551 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4552
4553 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4554 Node* st = in(i);
4555 intptr_t st_off = get_store_offset(st, phase);
4556 if (st_off < 0)
4557 break; // unknown junk in the inits
4558 if (st->in(MemNode::Memory) != zmem)
4559 break; // complicated store chains somehow in list
4560
4561 int st_size = st->as_Store()->memory_size();
4562 intptr_t next_init_off = st_off + st_size;
4563
4564 if (do_zeroing && zeroes_done < next_init_off) {
4565 // See if this store needs a zero before it or under it.
4566 intptr_t zeroes_needed = st_off;
4567
4568 if (st_size < BytesPerInt) {
4569 // Look for subword stores which only partially initialize words.
4570 // If we find some, we must lay down some word-level zeroes first,
4571 // underneath the subword stores.
4572 //
4573 // Examples:
4574 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4575 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4576 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4577 //
4578 // Note: coalesce_subword_stores may have already done this,
4579 // if it was prompted by constant non-zero subword initializers.
4580 // But this case can still arise with non-constant stores.
4581
4582 intptr_t next_full_store = find_next_fullword_store(i, phase);
4583
4584 // In the examples above:
4585 // in(i) p q r s x y z
4586 // st_off 12 13 14 15 12 13 14
4587 // st_size 1 1 1 1 1 1 1
4588 // next_full_s. 12 16 16 16 16 16 16
4589 // z's_done 12 16 16 16 12 16 12
4590 // z's_needed 12 16 16 16 16 16 16
4591 // zsize 0 0 0 0 4 0 4
4592 if (next_full_store < 0) {
4593 // Conservative tack: Zero to end of current word.
4594 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4595 } else {
4596 // Zero to beginning of next fully initialized word.
4597 // Or, don't zero at all, if we are already in that word.
4598 assert(next_full_store >= zeroes_needed, "must go forward");
4599 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4600 zeroes_needed = next_full_store;
4601 }
4602 }
4603
4604 if (zeroes_needed > zeroes_done) {
4605 intptr_t zsize = zeroes_needed - zeroes_done;
4606 // Do some incremental zeroing on rawmem, in parallel with inits.
4607 zeroes_done = align_down(zeroes_done, BytesPerInt);
4608 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4609 allocation()->in(AllocateNode::DefaultValue),
4610 allocation()->in(AllocateNode::RawDefaultValue),
4611 zeroes_done, zeroes_needed,
4612 phase);
4613 zeroes_done = zeroes_needed;
4614 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4615 do_zeroing = false; // leave the hole, next time
4616 }
4617 }
4618
4619 // Collect the store and move on:
4620 phase->replace_input_of(st, MemNode::Memory, inits);
4621 inits = st; // put it on the linearized chain
4622 set_req(i, zmem); // unhook from previous position
4623
4624 if (zeroes_done == st_off)
4625 zeroes_done = next_init_off;
4626
4627 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4628
4629 #ifdef ASSERT
4630 // Various order invariants. Weaker than stores_are_sane because
4631 // a large constant tile can be filled in by smaller non-constant stores.
4632 assert(st_off >= last_init_off, "inits do not reverse");
4633 last_init_off = st_off;
4634 const Type* val = nullptr;
4635 if (st_size >= BytesPerInt &&
4636 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4637 (int)val->basic_type() < (int)T_OBJECT) {
4638 assert(st_off >= last_tile_end, "tiles do not overlap");
4639 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4640 last_tile_end = MAX2(last_tile_end, next_init_off);
4641 } else {
4642 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4643 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4644 assert(st_off >= last_init_end, "inits do not overlap");
4645 last_init_end = next_init_off; // it's a non-tile
4646 }
4647 #endif //ASSERT
4648 }
4649
4650 remove_extra_zeroes(); // clear out all the zmems left over
4651 add_req(inits);
4652
4653 if (!(UseTLAB && ZeroTLAB)) {
4654 // If anything remains to be zeroed, zero it all now.
4655 zeroes_done = align_down(zeroes_done, BytesPerInt);
4656 // if it is the last unused 4 bytes of an instance, forget about it
4657 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4658 if (zeroes_done + BytesPerLong >= size_limit) {
4659 AllocateNode* alloc = allocation();
4660 assert(alloc != nullptr, "must be present");
4661 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
4662 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4663 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
4664 if (zeroes_done == k->layout_helper())
4665 zeroes_done = size_limit;
4666 }
4667 }
4668 if (zeroes_done < size_limit) {
4669 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4670 allocation()->in(AllocateNode::DefaultValue),
4671 allocation()->in(AllocateNode::RawDefaultValue),
4672 zeroes_done, size_in_bytes, phase);
4673 }
4674 }
4675
4676 set_complete(phase);
4677 return rawmem;
4678 }
4679
4680
4681 #ifdef ASSERT
4682 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
4683 if (is_complete())
4684 return true; // stores could be anything at this point
4685 assert(allocation() != nullptr, "must be present");
4686 intptr_t last_off = allocation()->minimum_header_size();
4687 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4688 Node* st = in(i);
4689 intptr_t st_off = get_store_offset(st, phase);
4690 if (st_off < 0) continue; // ignore dead garbage
4691 if (last_off > st_off) {
4692 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4693 this->dump(2);
4694 assert(false, "ascending store offsets");
4695 return false;
4696 }
4697 last_off = st_off + st->as_Store()->memory_size();
4698 }
4699 return true;
4700 }
4701 #endif //ASSERT
4702
4703
4704
4705
4706 //============================MergeMemNode=====================================
4707 //
4708 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4709 // contributing store or call operations. Each contributor provides the memory
4710 // state for a particular "alias type" (see Compile::alias_type). For example,
4711 // if a MergeMem has an input X for alias category #6, then any memory reference
4712 // to alias category #6 may use X as its memory state input, as an exact equivalent
4713 // to using the MergeMem as a whole.
4714 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4715 //
4716 // (Here, the <N> notation gives the index of the relevant adr_type.)
4717 //
4718 // In one special case (and more cases in the future), alias categories overlap.
4719 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4720 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4721 // it is exactly equivalent to that state W:
4722 // MergeMem(<Bot>: W) <==> W
4723 //
4724 // Usually, the merge has more than one input. In that case, where inputs
4725 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4726 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4727 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4728 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4729 //
4730 // A merge can take a "wide" memory state as one of its narrow inputs.
4731 // This simply means that the merge observes out only the relevant parts of
4732 // the wide input. That is, wide memory states arriving at narrow merge inputs
4733 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4734 //
4735 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4736 // and that memory slices "leak through":
4737 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4738 //
4739 // But, in such a cascade, repeated memory slices can "block the leak":
4740 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4741 //
4742 // In the last example, Y is not part of the combined memory state of the
4743 // outermost MergeMem. The system must, of course, prevent unschedulable
4744 // memory states from arising, so you can be sure that the state Y is somehow
4745 // a precursor to state Y'.
4746 //
4747 //
4748 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4749 // of each MergeMemNode array are exactly the numerical alias indexes, including
4750 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4751 // Compile::alias_type (and kin) produce and manage these indexes.
4752 //
4753 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4754 // (Note that this provides quick access to the top node inside MergeMem methods,
4755 // without the need to reach out via TLS to Compile::current.)
4756 //
4757 // As a consequence of what was just described, a MergeMem that represents a full
4758 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4759 // containing all alias categories.
4760 //
4761 // MergeMem nodes never (?) have control inputs, so in(0) is null.
4762 //
4763 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4764 // a memory state for the alias type <N>, or else the top node, meaning that
4765 // there is no particular input for that alias type. Note that the length of
4766 // a MergeMem is variable, and may be extended at any time to accommodate new
4767 // memory states at larger alias indexes. When merges grow, they are of course
4768 // filled with "top" in the unused in() positions.
4769 //
4770 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4771 // (Top was chosen because it works smoothly with passes like GCM.)
4772 //
4773 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4774 // the type of random VM bits like TLS references.) Since it is always the
4775 // first non-Bot memory slice, some low-level loops use it to initialize an
4776 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4777 //
4778 //
4779 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4780 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4781 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4782 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4783 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4784 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4785 //
4786 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4787 // really that different from the other memory inputs. An abbreviation called
4788 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4789 //
4790 //
4791 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4792 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4793 // that "emerges though" the base memory will be marked as excluding the alias types
4794 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4795 //
4796 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4797 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4798 //
4799 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4800 // (It is currently unimplemented.) As you can see, the resulting merge is
4801 // actually a disjoint union of memory states, rather than an overlay.
4802 //
4803
4804 //------------------------------MergeMemNode-----------------------------------
4805 Node* MergeMemNode::make_empty_memory() {
4806 Node* empty_memory = (Node*) Compile::current()->top();
4807 assert(empty_memory->is_top(), "correct sentinel identity");
4808 return empty_memory;
4809 }
4810
4811 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4812 init_class_id(Class_MergeMem);
4813 // all inputs are nullified in Node::Node(int)
4814 // set_input(0, nullptr); // no control input
4815
4816 // Initialize the edges uniformly to top, for starters.
4817 Node* empty_mem = make_empty_memory();
4818 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4819 init_req(i,empty_mem);
4820 }
4821 assert(empty_memory() == empty_mem, "");
4822
4823 if( new_base != nullptr && new_base->is_MergeMem() ) {
4824 MergeMemNode* mdef = new_base->as_MergeMem();
4825 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4826 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4827 mms.set_memory(mms.memory2());
4828 }
4829 assert(base_memory() == mdef->base_memory(), "");
4830 } else {
4831 set_base_memory(new_base);
4832 }
4833 }
4834
4835 // Make a new, untransformed MergeMem with the same base as 'mem'.
4836 // If mem is itself a MergeMem, populate the result with the same edges.
4837 MergeMemNode* MergeMemNode::make(Node* mem) {
4838 return new MergeMemNode(mem);
4839 }
4840
4841 //------------------------------cmp--------------------------------------------
4842 uint MergeMemNode::hash() const { return NO_HASH; }
4843 bool MergeMemNode::cmp( const Node &n ) const {
4844 return (&n == this); // Always fail except on self
4845 }
4846
4847 //------------------------------Identity---------------------------------------
4848 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4849 // Identity if this merge point does not record any interesting memory
4850 // disambiguations.
4851 Node* base_mem = base_memory();
4852 Node* empty_mem = empty_memory();
4853 if (base_mem != empty_mem) { // Memory path is not dead?
4854 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4855 Node* mem = in(i);
4856 if (mem != empty_mem && mem != base_mem) {
4857 return this; // Many memory splits; no change
4858 }
4859 }
4860 }
4861 return base_mem; // No memory splits; ID on the one true input
4862 }
4863
4864 //------------------------------Ideal------------------------------------------
4865 // This method is invoked recursively on chains of MergeMem nodes
4866 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4867 // Remove chain'd MergeMems
4868 //
4869 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4870 // relative to the "in(Bot)". Since we are patching both at the same time,
4871 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4872 // but rewrite each "in(i)" relative to the new "in(Bot)".
4873 Node *progress = nullptr;
4874
4875
4876 Node* old_base = base_memory();
4877 Node* empty_mem = empty_memory();
4878 if (old_base == empty_mem)
4879 return nullptr; // Dead memory path.
4880
4881 MergeMemNode* old_mbase;
4882 if (old_base != nullptr && old_base->is_MergeMem())
4883 old_mbase = old_base->as_MergeMem();
4884 else
4885 old_mbase = nullptr;
4886 Node* new_base = old_base;
4887
4888 // simplify stacked MergeMems in base memory
4889 if (old_mbase) new_base = old_mbase->base_memory();
4890
4891 // the base memory might contribute new slices beyond my req()
4892 if (old_mbase) grow_to_match(old_mbase);
4893
4894 // Note: We do not call verify_sparse on entry, because inputs
4895 // can normalize to the base_memory via subsume_node or similar
4896 // mechanisms. This method repairs that damage.
4897
4898 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4899
4900 // Look at each slice.
4901 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4902 Node* old_in = in(i);
4903 // calculate the old memory value
4904 Node* old_mem = old_in;
4905 if (old_mem == empty_mem) old_mem = old_base;
4906 assert(old_mem == memory_at(i), "");
4907
4908 // maybe update (reslice) the old memory value
4909
4910 // simplify stacked MergeMems
4911 Node* new_mem = old_mem;
4912 MergeMemNode* old_mmem;
4913 if (old_mem != nullptr && old_mem->is_MergeMem())
4914 old_mmem = old_mem->as_MergeMem();
4915 else
4916 old_mmem = nullptr;
4917 if (old_mmem == this) {
4918 // This can happen if loops break up and safepoints disappear.
4919 // A merge of BotPtr (default) with a RawPtr memory derived from a
4920 // safepoint can be rewritten to a merge of the same BotPtr with
4921 // the BotPtr phi coming into the loop. If that phi disappears
4922 // also, we can end up with a self-loop of the mergemem.
4923 // In general, if loops degenerate and memory effects disappear,
4924 // a mergemem can be left looking at itself. This simply means
4925 // that the mergemem's default should be used, since there is
4926 // no longer any apparent effect on this slice.
4927 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4928 // from start. Update the input to TOP.
4929 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4930 }
4931 else if (old_mmem != nullptr) {
4932 new_mem = old_mmem->memory_at(i);
4933 }
4934 // else preceding memory was not a MergeMem
4935
4936 // maybe store down a new value
4937 Node* new_in = new_mem;
4938 if (new_in == new_base) new_in = empty_mem;
4939
4940 if (new_in != old_in) {
4941 // Warning: Do not combine this "if" with the previous "if"
4942 // A memory slice might have be be rewritten even if it is semantically
4943 // unchanged, if the base_memory value has changed.
4944 set_req_X(i, new_in, phase);
4945 progress = this; // Report progress
4946 }
4947 }
4948
4949 if (new_base != old_base) {
4950 set_req_X(Compile::AliasIdxBot, new_base, phase);
4951 // Don't use set_base_memory(new_base), because we need to update du.
4952 assert(base_memory() == new_base, "");
4953 progress = this;
4954 }
4955
4956 if( base_memory() == this ) {
4957 // a self cycle indicates this memory path is dead
4958 set_req(Compile::AliasIdxBot, empty_mem);
4959 }
4960
4961 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4962 // Recursion must occur after the self cycle check above
4963 if( base_memory()->is_MergeMem() ) {
4964 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4965 Node *m = phase->transform(new_mbase); // Rollup any cycles
4966 if( m != nullptr &&
4967 (m->is_top() ||
4968 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4969 // propagate rollup of dead cycle to self
4970 set_req(Compile::AliasIdxBot, empty_mem);
4971 }
4972 }
4973
4974 if( base_memory() == empty_mem ) {
4975 progress = this;
4976 // Cut inputs during Parse phase only.
4977 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4978 if( !can_reshape ) {
4979 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4980 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4981 }
4982 }
4983 }
4984
4985 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4986 // Check if PhiNode::Ideal's "Split phis through memory merges"
4987 // transform should be attempted. Look for this->phi->this cycle.
4988 uint merge_width = req();
4989 if (merge_width > Compile::AliasIdxRaw) {
4990 PhiNode* phi = base_memory()->as_Phi();
4991 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4992 if (phi->in(i) == this) {
4993 phase->is_IterGVN()->_worklist.push(phi);
4994 break;
4995 }
4996 }
4997 }
4998 }
4999
5000 assert(progress || verify_sparse(), "please, no dups of base");
5001 return progress;
5002 }
5003
5004 //-------------------------set_base_memory-------------------------------------
5005 void MergeMemNode::set_base_memory(Node *new_base) {
5006 Node* empty_mem = empty_memory();
5007 set_req(Compile::AliasIdxBot, new_base);
5008 assert(memory_at(req()) == new_base, "must set default memory");
5009 // Clear out other occurrences of new_base:
5010 if (new_base != empty_mem) {
5011 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5012 if (in(i) == new_base) set_req(i, empty_mem);
5013 }
5014 }
5015 }
5016
5017 //------------------------------out_RegMask------------------------------------
5018 const RegMask &MergeMemNode::out_RegMask() const {
5019 return RegMask::Empty;
5020 }
5021
5022 //------------------------------dump_spec--------------------------------------
5023 #ifndef PRODUCT
5024 void MergeMemNode::dump_spec(outputStream *st) const {
5025 st->print(" {");
5026 Node* base_mem = base_memory();
5027 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5028 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
5029 if (mem == base_mem) { st->print(" -"); continue; }
5030 st->print( " N%d:", mem->_idx );
5031 Compile::current()->get_adr_type(i)->dump_on(st);
5032 }
5033 st->print(" }");
5034 }
5035 #endif // !PRODUCT
5036
5037
5038 #ifdef ASSERT
5039 static bool might_be_same(Node* a, Node* b) {
5040 if (a == b) return true;
5041 if (!(a->is_Phi() || b->is_Phi())) return false;
5042 // phis shift around during optimization
5043 return true; // pretty stupid...
5044 }
5045
5046 // verify a narrow slice (either incoming or outgoing)
5047 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5048 if (!VerifyAliases) return; // don't bother to verify unless requested
5049 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
5050 if (Node::in_dump()) return; // muzzle asserts when printing
5051 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5052 assert(n != nullptr, "");
5053 // Elide intervening MergeMem's
5054 while (n->is_MergeMem()) {
5055 n = n->as_MergeMem()->memory_at(alias_idx);
5056 }
5057 Compile* C = Compile::current();
5058 const TypePtr* n_adr_type = n->adr_type();
5059 if (n == m->empty_memory()) {
5060 // Implicit copy of base_memory()
5061 } else if (n_adr_type != TypePtr::BOTTOM) {
5062 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
5063 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5064 } else {
5065 // A few places like make_runtime_call "know" that VM calls are narrow,
5066 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5067 bool expected_wide_mem = false;
5068 if (n == m->base_memory()) {
5069 expected_wide_mem = true;
5070 } else if (alias_idx == Compile::AliasIdxRaw ||
5071 n == m->memory_at(Compile::AliasIdxRaw)) {
5072 expected_wide_mem = true;
5073 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5074 // memory can "leak through" calls on channels that
5075 // are write-once. Allow this also.
5076 expected_wide_mem = true;
5077 }
5078 assert(expected_wide_mem, "expected narrow slice replacement");
5079 }
5080 }
5081 #else // !ASSERT
5082 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
5083 #endif
5084
5085
5086 //-----------------------------memory_at---------------------------------------
5087 Node* MergeMemNode::memory_at(uint alias_idx) const {
5088 assert(alias_idx >= Compile::AliasIdxRaw ||
5089 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
5090 "must avoid base_memory and AliasIdxTop");
5091
5092 // Otherwise, it is a narrow slice.
5093 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5094 if (is_empty_memory(n)) {
5095 // the array is sparse; empty slots are the "top" node
5096 n = base_memory();
5097 assert(Node::in_dump()
5098 || n == nullptr || n->bottom_type() == Type::TOP
5099 || n->adr_type() == nullptr // address is TOP
5100 || n->adr_type() == TypePtr::BOTTOM
5101 || n->adr_type() == TypeRawPtr::BOTTOM
5102 || !Compile::current()->do_aliasing(),
5103 "must be a wide memory");
5104 // do_aliasing == false if we are organizing the memory states manually.
5105 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5106 } else {
5107 // make sure the stored slice is sane
5108 #ifdef ASSERT
5109 if (VMError::is_error_reported() || Node::in_dump()) {
5110 } else if (might_be_same(n, base_memory())) {
5111 // Give it a pass: It is a mostly harmless repetition of the base.
5112 // This can arise normally from node subsumption during optimization.
5113 } else {
5114 verify_memory_slice(this, alias_idx, n);
5115 }
5116 #endif
5117 }
5118 return n;
5119 }
5120
5121 //---------------------------set_memory_at-------------------------------------
5122 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5123 verify_memory_slice(this, alias_idx, n);
5124 Node* empty_mem = empty_memory();
5125 if (n == base_memory()) n = empty_mem; // collapse default
5126 uint need_req = alias_idx+1;
5127 if (req() < need_req) {
5128 if (n == empty_mem) return; // already the default, so do not grow me
5129 // grow the sparse array
5130 do {
5131 add_req(empty_mem);
5132 } while (req() < need_req);
5133 }
5134 set_req( alias_idx, n );
5135 }
5136
5137
5138
5139 //--------------------------iteration_setup------------------------------------
5140 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5141 if (other != nullptr) {
5142 grow_to_match(other);
5143 // invariant: the finite support of mm2 is within mm->req()
5144 #ifdef ASSERT
5145 for (uint i = req(); i < other->req(); i++) {
5146 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5147 }
5148 #endif
5149 }
5150 // Replace spurious copies of base_memory by top.
5151 Node* base_mem = base_memory();
5152 if (base_mem != nullptr && !base_mem->is_top()) {
5153 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5154 if (in(i) == base_mem)
5155 set_req(i, empty_memory());
5156 }
5157 }
5158 }
5159
5160 //---------------------------grow_to_match-------------------------------------
5161 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5162 Node* empty_mem = empty_memory();
5163 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5164 // look for the finite support of the other memory
5165 for (uint i = other->req(); --i >= req(); ) {
5166 if (other->in(i) != empty_mem) {
5167 uint new_len = i+1;
5168 while (req() < new_len) add_req(empty_mem);
5169 break;
5170 }
5171 }
5172 }
5173
5174 //---------------------------verify_sparse-------------------------------------
5175 #ifndef PRODUCT
5176 bool MergeMemNode::verify_sparse() const {
5177 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5178 Node* base_mem = base_memory();
5179 // The following can happen in degenerate cases, since empty==top.
5180 if (is_empty_memory(base_mem)) return true;
5181 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5182 assert(in(i) != nullptr, "sane slice");
5183 if (in(i) == base_mem) return false; // should have been the sentinel value!
5184 }
5185 return true;
5186 }
5187
5188 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5189 Node* n;
5190 n = mm->in(idx);
5191 if (mem == n) return true; // might be empty_memory()
5192 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5193 if (mem == n) return true;
5194 return false;
5195 }
5196 #endif // !PRODUCT