1 /*
2 * Copyright (c) 1997, 2019, 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.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "memory/allocation.inline.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "oops/objArrayKlass.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/arraycopynode.hpp"
35 #include "opto/cfgnode.hpp"
36 #include "opto/compile.hpp"
37 #include "opto/connode.hpp"
38 #include "opto/convertnode.hpp"
39 #include "opto/loopnode.hpp"
40 #include "opto/machnode.hpp"
41 #include "opto/matcher.hpp"
42 #include "opto/memnode.hpp"
43 #include "opto/mulnode.hpp"
44 #include "opto/narrowptrnode.hpp"
45 #include "opto/phaseX.hpp"
46 #include "opto/regmask.hpp"
47 #include "opto/rootnode.hpp"
48 #include "utilities/align.hpp"
49 #include "utilities/copy.hpp"
50 #include "utilities/macros.hpp"
51 #include "utilities/vmError.hpp"
52 #if INCLUDE_ZGC
53 #include "gc/z/c2/zBarrierSetC2.hpp"
54 #endif
55 #if INCLUDE_SHENANDOAHGC
56 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
57 #endif
58
59 // Portions of code courtesy of Clifford Click
60
61 // Optimization - Graph Style
62
63 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
64
65 //=============================================================================
66 uint MemNode::size_of() const { return sizeof(*this); }
67
68 const TypePtr *MemNode::adr_type() const {
69 Node* adr = in(Address);
70 if (adr == NULL) return NULL; // node is dead
71 const TypePtr* cross_check = NULL;
72 DEBUG_ONLY(cross_check = _adr_type);
73 return calculate_adr_type(adr->bottom_type(), cross_check);
74 }
75
76 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
77 if (adr != NULL) {
78 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
79 return true;
80 }
81 }
82 return false;
83 }
84
85 #ifndef PRODUCT
86 void MemNode::dump_spec(outputStream *st) const {
87 if (in(Address) == NULL) return; // node is dead
88 #ifndef ASSERT
89 // fake the missing field
90 const TypePtr* _adr_type = NULL;
91 if (in(Address) != NULL)
92 _adr_type = in(Address)->bottom_type()->isa_ptr();
93 #endif
94 dump_adr_type(this, _adr_type, st);
95
96 Compile* C = Compile::current();
97 if (C->alias_type(_adr_type)->is_volatile()) {
98 st->print(" Volatile!");
99 }
100 if (_unaligned_access) {
101 st->print(" unaligned");
102 }
103 if (_mismatched_access) {
104 st->print(" mismatched");
105 }
106 if (_unsafe_access) {
107 st->print(" unsafe");
108 }
109 }
110
111 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
112 st->print(" @");
113 if (adr_type == NULL) {
114 st->print("NULL");
115 } else {
116 adr_type->dump_on(st);
117 Compile* C = Compile::current();
118 Compile::AliasType* atp = NULL;
119 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
120 if (atp == NULL)
121 st->print(", idx=?\?;");
122 else if (atp->index() == Compile::AliasIdxBot)
123 st->print(", idx=Bot;");
124 else if (atp->index() == Compile::AliasIdxTop)
125 st->print(", idx=Top;");
126 else if (atp->index() == Compile::AliasIdxRaw)
127 st->print(", idx=Raw;");
128 else {
129 ciField* field = atp->field();
130 if (field) {
131 st->print(", name=");
132 field->print_name_on(st);
133 }
134 st->print(", idx=%d;", atp->index());
135 }
136 }
137 }
138
139 extern void print_alias_types();
140
141 #endif
142
143 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
144 assert((t_oop != NULL), "sanity");
145 bool is_instance = t_oop->is_known_instance_field();
146 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
147 (load != NULL) && load->is_Load() &&
148 (phase->is_IterGVN() != NULL);
149 if (!(is_instance || is_boxed_value_load))
150 return mchain; // don't try to optimize non-instance types
151 uint instance_id = t_oop->instance_id();
152 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
153 Node *prev = NULL;
154 Node *result = mchain;
155 while (prev != result) {
156 prev = result;
157 if (result == start_mem)
158 break; // hit one of our sentinels
159 // skip over a call which does not affect this memory slice
160 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
161 Node *proj_in = result->in(0);
162 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
163 break; // hit one of our sentinels
164 } else if (proj_in->is_Call()) {
165 // ArrayCopyNodes processed here as well
166 CallNode *call = proj_in->as_Call();
167 if (!call->may_modify(t_oop, phase)) { // returns false for instances
168 result = call->in(TypeFunc::Memory);
169 }
170 } else if (proj_in->is_Initialize()) {
171 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
172 // Stop if this is the initialization for the object instance which
173 // contains this memory slice, otherwise skip over it.
174 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
175 break;
176 }
177 if (is_instance) {
178 result = proj_in->in(TypeFunc::Memory);
179 } else if (is_boxed_value_load) {
180 Node* klass = alloc->in(AllocateNode::KlassNode);
181 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
182 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
183 result = proj_in->in(TypeFunc::Memory); // not related allocation
184 }
185 }
186 } else if (proj_in->is_MemBar()) {
187 ArrayCopyNode* ac = NULL;
188 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
189 break;
190 }
191 result = proj_in->in(TypeFunc::Memory);
192 } else {
193 assert(false, "unexpected projection");
194 }
195 } else if (result->is_ClearArray()) {
196 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
197 // Can not bypass initialization of the instance
198 // we are looking for.
199 break;
200 }
201 // Otherwise skip it (the call updated 'result' value).
202 } else if (result->is_MergeMem()) {
203 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
204 }
205 }
206 return result;
207 }
208
209 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
210 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
211 if (t_oop == NULL)
212 return mchain; // don't try to optimize non-oop types
213 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
214 bool is_instance = t_oop->is_known_instance_field();
215 PhaseIterGVN *igvn = phase->is_IterGVN();
216 if (is_instance && igvn != NULL && result->is_Phi()) {
217 PhiNode *mphi = result->as_Phi();
218 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
219 const TypePtr *t = mphi->adr_type();
220 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
221 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
222 t->is_oopptr()->cast_to_exactness(true)
223 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
224 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
225 // clone the Phi with our address type
226 result = mphi->split_out_instance(t_adr, igvn);
227 } else {
228 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
229 }
230 }
231 return result;
232 }
233
234 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
235 uint alias_idx = phase->C->get_alias_index(tp);
236 Node *mem = mmem;
237 #ifdef ASSERT
238 {
239 // Check that current type is consistent with the alias index used during graph construction
240 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
241 bool consistent = adr_check == NULL || adr_check->empty() ||
242 phase->C->must_alias(adr_check, alias_idx );
243 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
244 if( !consistent && adr_check != NULL && !adr_check->empty() &&
245 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
246 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
247 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
248 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
249 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
250 // don't assert if it is dead code.
251 consistent = true;
252 }
253 if( !consistent ) {
254 st->print("alias_idx==%d, adr_check==", alias_idx);
255 if( adr_check == NULL ) {
256 st->print("NULL");
257 } else {
258 adr_check->dump();
259 }
260 st->cr();
261 print_alias_types();
262 assert(consistent, "adr_check must match alias idx");
263 }
264 }
265 #endif
266 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
267 // means an array I have not precisely typed yet. Do not do any
268 // alias stuff with it any time soon.
269 const TypeOopPtr *toop = tp->isa_oopptr();
270 if( tp->base() != Type::AnyPtr &&
271 !(toop &&
272 toop->klass() != NULL &&
273 toop->klass()->is_java_lang_Object() &&
274 toop->offset() == Type::OffsetBot) ) {
275 // compress paths and change unreachable cycles to TOP
276 // If not, we can update the input infinitely along a MergeMem cycle
277 // Equivalent code in PhiNode::Ideal
278 Node* m = phase->transform(mmem);
279 // If transformed to a MergeMem, get the desired slice
280 // Otherwise the returned node represents memory for every slice
281 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
282 // Update input if it is progress over what we have now
283 }
284 return mem;
285 }
286
287 //--------------------------Ideal_common---------------------------------------
288 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
289 // Unhook non-raw memories from complete (macro-expanded) initializations.
290 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
291 // If our control input is a dead region, kill all below the region
292 Node *ctl = in(MemNode::Control);
293 if (ctl && remove_dead_region(phase, can_reshape))
294 return this;
295 ctl = in(MemNode::Control);
296 // Don't bother trying to transform a dead node
297 if (ctl && ctl->is_top()) return NodeSentinel;
298
299 PhaseIterGVN *igvn = phase->is_IterGVN();
300 // Wait if control on the worklist.
301 if (ctl && can_reshape && igvn != NULL) {
302 Node* bol = NULL;
303 Node* cmp = NULL;
304 if (ctl->in(0)->is_If()) {
305 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
306 bol = ctl->in(0)->in(1);
307 if (bol->is_Bool())
308 cmp = ctl->in(0)->in(1)->in(1);
309 }
310 if (igvn->_worklist.member(ctl) ||
311 (bol != NULL && igvn->_worklist.member(bol)) ||
312 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
313 // This control path may be dead.
314 // Delay this memory node transformation until the control is processed.
315 phase->is_IterGVN()->_worklist.push(this);
316 return NodeSentinel; // caller will return NULL
317 }
318 }
319 // Ignore if memory is dead, or self-loop
320 Node *mem = in(MemNode::Memory);
321 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
322 assert(mem != this, "dead loop in MemNode::Ideal");
323
324 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
325 // This memory slice may be dead.
326 // Delay this mem node transformation until the memory is processed.
327 phase->is_IterGVN()->_worklist.push(this);
328 return NodeSentinel; // caller will return NULL
329 }
330
331 Node *address = in(MemNode::Address);
332 const Type *t_adr = phase->type(address);
333 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
334
335 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
336 // Unsafe off-heap access with zero address. Remove access and other control users
337 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
338 assert(ctl != NULL, "unsafe accesses should be control dependent");
339 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
340 Node* u = ctl->fast_out(i);
341 if (u != ctl) {
342 igvn->rehash_node_delayed(u);
343 int nb = u->replace_edge(ctl, phase->C->top());
344 --i, imax -= nb;
345 }
346 }
347 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
348 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
349 phase->C->root()->add_req(halt);
350 return this;
351 }
352
353 if (can_reshape && igvn != NULL &&
354 (igvn->_worklist.member(address) ||
355 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
356 // The address's base and type may change when the address is processed.
357 // Delay this mem node transformation until the address is processed.
358 phase->is_IterGVN()->_worklist.push(this);
359 return NodeSentinel; // caller will return NULL
360 }
361
362 // Do NOT remove or optimize the next lines: ensure a new alias index
363 // is allocated for an oop pointer type before Escape Analysis.
364 // Note: C++ will not remove it since the call has side effect.
365 if (t_adr->isa_oopptr()) {
366 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
367 }
368
369 Node* base = NULL;
370 if (address->is_AddP()) {
371 base = address->in(AddPNode::Base);
372 }
373 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
374 !t_adr->isa_rawptr()) {
375 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
376 // Skip this node optimization if its address has TOP base.
377 return NodeSentinel; // caller will return NULL
378 }
379
380 // Avoid independent memory operations
381 Node* old_mem = mem;
382
383 // The code which unhooks non-raw memories from complete (macro-expanded)
384 // initializations was removed. After macro-expansion all stores catched
385 // by Initialize node became raw stores and there is no information
386 // which memory slices they modify. So it is unsafe to move any memory
387 // operation above these stores. Also in most cases hooked non-raw memories
388 // were already unhooked by using information from detect_ptr_independence()
389 // and find_previous_store().
390
391 if (mem->is_MergeMem()) {
392 MergeMemNode* mmem = mem->as_MergeMem();
393 const TypePtr *tp = t_adr->is_ptr();
394
395 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
396 }
397
398 if (mem != old_mem) {
399 set_req(MemNode::Memory, mem);
400 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
401 igvn->_worklist.push(old_mem);
402 }
403 if (phase->type(mem) == Type::TOP) return NodeSentinel;
404 return this;
405 }
406
407 // let the subclass continue analyzing...
408 return NULL;
409 }
410
411 // Helper function for proving some simple control dominations.
412 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
413 // Already assumes that 'dom' is available at 'sub', and that 'sub'
414 // is not a constant (dominated by the method's StartNode).
415 // Used by MemNode::find_previous_store to prove that the
416 // control input of a memory operation predates (dominates)
417 // an allocation it wants to look past.
418 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
419 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
420 return false; // Conservative answer for dead code
421
422 // Check 'dom'. Skip Proj and CatchProj nodes.
423 dom = dom->find_exact_control(dom);
424 if (dom == NULL || dom->is_top())
425 return false; // Conservative answer for dead code
426
427 if (dom == sub) {
428 // For the case when, for example, 'sub' is Initialize and the original
429 // 'dom' is Proj node of the 'sub'.
430 return false;
431 }
432
433 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
434 return true;
435
436 // 'dom' dominates 'sub' if its control edge and control edges
437 // of all its inputs dominate or equal to sub's control edge.
438
439 // Currently 'sub' is either Allocate, Initialize or Start nodes.
440 // Or Region for the check in LoadNode::Ideal();
441 // 'sub' should have sub->in(0) != NULL.
442 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
443 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
444
445 // Get control edge of 'sub'.
446 Node* orig_sub = sub;
447 sub = sub->find_exact_control(sub->in(0));
448 if (sub == NULL || sub->is_top())
449 return false; // Conservative answer for dead code
450
451 assert(sub->is_CFG(), "expecting control");
452
453 if (sub == dom)
454 return true;
455
456 if (sub->is_Start() || sub->is_Root())
457 return false;
458
459 {
460 // Check all control edges of 'dom'.
461
462 ResourceMark rm;
463 Arena* arena = Thread::current()->resource_area();
464 Node_List nlist(arena);
465 Unique_Node_List dom_list(arena);
466
467 dom_list.push(dom);
468 bool only_dominating_controls = false;
469
470 for (uint next = 0; next < dom_list.size(); next++) {
471 Node* n = dom_list.at(next);
472 if (n == orig_sub)
473 return false; // One of dom's inputs dominated by sub.
474 if (!n->is_CFG() && n->pinned()) {
475 // Check only own control edge for pinned non-control nodes.
476 n = n->find_exact_control(n->in(0));
477 if (n == NULL || n->is_top())
478 return false; // Conservative answer for dead code
479 assert(n->is_CFG(), "expecting control");
480 dom_list.push(n);
481 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
482 only_dominating_controls = true;
483 } else if (n->is_CFG()) {
484 if (n->dominates(sub, nlist))
485 only_dominating_controls = true;
486 else
487 return false;
488 } else {
489 // First, own control edge.
490 Node* m = n->find_exact_control(n->in(0));
491 if (m != NULL) {
492 if (m->is_top())
493 return false; // Conservative answer for dead code
494 dom_list.push(m);
495 }
496 // Now, the rest of edges.
497 uint cnt = n->req();
498 for (uint i = 1; i < cnt; i++) {
499 m = n->find_exact_control(n->in(i));
500 if (m == NULL || m->is_top())
501 continue;
502 dom_list.push(m);
503 }
504 }
505 }
506 return only_dominating_controls;
507 }
508 }
509
510 //---------------------detect_ptr_independence---------------------------------
511 // Used by MemNode::find_previous_store to prove that two base
512 // pointers are never equal.
513 // The pointers are accompanied by their associated allocations,
514 // if any, which have been previously discovered by the caller.
515 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
516 Node* p2, AllocateNode* a2,
517 PhaseTransform* phase) {
518 // Attempt to prove that these two pointers cannot be aliased.
519 // They may both manifestly be allocations, and they should differ.
520 // Or, if they are not both allocations, they can be distinct constants.
521 // Otherwise, one is an allocation and the other a pre-existing value.
522 if (a1 == NULL && a2 == NULL) { // neither an allocation
523 return (p1 != p2) && p1->is_Con() && p2->is_Con();
524 } else if (a1 != NULL && a2 != NULL) { // both allocations
525 return (a1 != a2);
526 } else if (a1 != NULL) { // one allocation a1
527 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
528 return all_controls_dominate(p2, a1);
529 } else { //(a2 != NULL) // one allocation a2
530 return all_controls_dominate(p1, a2);
531 }
532 return false;
533 }
534
535
536 // Find an arraycopy that must have set (can_see_stored_value=true) or
537 // could have set (can_see_stored_value=false) the value for this load
538 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
539 ArrayCopyNode* ac = find_array_copy_clone(phase, ld_alloc, mem);
540 if (ac != NULL) {
541 return ac;
542 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
543 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
544
545 if (ac->is_arraycopy_validated() ||
546 ac->is_copyof_validated() ||
547 ac->is_copyofrange_validated()) {
548 Node* ld_addp = in(MemNode::Address);
549 if (ld_addp->is_AddP()) {
550 Node* ld_base = ld_addp->in(AddPNode::Address);
551 Node* ld_offs = ld_addp->in(AddPNode::Offset);
552
553 Node* dest = ac->in(ArrayCopyNode::Dest);
554
555 if (dest == ld_base) {
556 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
557 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
558 return ac;
559 }
560 if (!can_see_stored_value) {
561 mem = ac->in(TypeFunc::Memory);
562 }
563 }
564 }
565 }
566 }
567 return NULL;
568 }
569
570 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseTransform* phase, Node* ld_alloc, Node* mem) const {
571 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
572 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
573 if (ld_alloc != NULL) {
574 // Check if there is an array copy for a clone
575 Node* mb = mem->in(0);
576 ArrayCopyNode* ac = NULL;
577 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
578 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
579 ac = mb->in(0)->in(0)->as_ArrayCopy();
580 } else {
581 // Step over GC barrier when ReduceInitialCardMarks is disabled
582 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
583 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
584
585 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
586 ac = control_proj_ac->in(0)->as_ArrayCopy();
587 }
588 }
589
590 if (ac != NULL && ac->is_clonebasic()) {
591 intptr_t offset;
592 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
593 if (alloc != NULL && alloc == ld_alloc) {
594 return ac;
595 }
596 }
597 }
598 }
599 return NULL;
600 }
601
602 // The logic for reordering loads and stores uses four steps:
603 // (a) Walk carefully past stores and initializations which we
604 // can prove are independent of this load.
605 // (b) Observe that the next memory state makes an exact match
606 // with self (load or store), and locate the relevant store.
607 // (c) Ensure that, if we were to wire self directly to the store,
608 // the optimizer would fold it up somehow.
609 // (d) Do the rewiring, and return, depending on some other part of
610 // the optimizer to fold up the load.
611 // This routine handles steps (a) and (b). Steps (c) and (d) are
612 // specific to loads and stores, so they are handled by the callers.
613 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
614 //
615 Node* MemNode::find_previous_store(PhaseTransform* phase) {
616 Node* ctrl = in(MemNode::Control);
617 Node* adr = in(MemNode::Address);
618 intptr_t offset = 0;
619 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
620 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
621
622 if (offset == Type::OffsetBot)
623 return NULL; // cannot unalias unless there are precise offsets
624
625 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
626 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
627
628 intptr_t size_in_bytes = memory_size();
629
630 Node* mem = in(MemNode::Memory); // start searching here...
631
632 int cnt = 50; // Cycle limiter
633 for (;;) { // While we can dance past unrelated stores...
634 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
635
636 Node* prev = mem;
637 if (mem->is_Store()) {
638 Node* st_adr = mem->in(MemNode::Address);
639 intptr_t st_offset = 0;
640 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
641 if (st_base == NULL)
642 break; // inscrutable pointer
643
644 // For raw accesses it's not enough to prove that constant offsets don't intersect.
645 // We need the bases to be the equal in order for the offset check to make sense.
646 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
647 break;
648 }
649
650 if (st_offset != offset && st_offset != Type::OffsetBot) {
651 const int MAX_STORE = BytesPerLong;
652 if (st_offset >= offset + size_in_bytes ||
653 st_offset <= offset - MAX_STORE ||
654 st_offset <= offset - mem->as_Store()->memory_size()) {
655 // Success: The offsets are provably independent.
656 // (You may ask, why not just test st_offset != offset and be done?
657 // The answer is that stores of different sizes can co-exist
658 // in the same sequence of RawMem effects. We sometimes initialize
659 // a whole 'tile' of array elements with a single jint or jlong.)
660 mem = mem->in(MemNode::Memory);
661 continue; // (a) advance through independent store memory
662 }
663 }
664 if (st_base != base &&
665 detect_ptr_independence(base, alloc,
666 st_base,
667 AllocateNode::Ideal_allocation(st_base, phase),
668 phase)) {
669 // Success: The bases are provably independent.
670 mem = mem->in(MemNode::Memory);
671 continue; // (a) advance through independent store memory
672 }
673
674 // (b) At this point, if the bases or offsets do not agree, we lose,
675 // since we have not managed to prove 'this' and 'mem' independent.
676 if (st_base == base && st_offset == offset) {
677 return mem; // let caller handle steps (c), (d)
678 }
679
680 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
681 InitializeNode* st_init = mem->in(0)->as_Initialize();
682 AllocateNode* st_alloc = st_init->allocation();
683 if (st_alloc == NULL)
684 break; // something degenerated
685 bool known_identical = false;
686 bool known_independent = false;
687 if (alloc == st_alloc)
688 known_identical = true;
689 else if (alloc != NULL)
690 known_independent = true;
691 else if (all_controls_dominate(this, st_alloc))
692 known_independent = true;
693
694 if (known_independent) {
695 // The bases are provably independent: Either they are
696 // manifestly distinct allocations, or else the control
697 // of this load dominates the store's allocation.
698 int alias_idx = phase->C->get_alias_index(adr_type());
699 if (alias_idx == Compile::AliasIdxRaw) {
700 mem = st_alloc->in(TypeFunc::Memory);
701 } else {
702 mem = st_init->memory(alias_idx);
703 }
704 continue; // (a) advance through independent store memory
705 }
706
707 // (b) at this point, if we are not looking at a store initializing
708 // the same allocation we are loading from, we lose.
709 if (known_identical) {
710 // From caller, can_see_stored_value will consult find_captured_store.
711 return mem; // let caller handle steps (c), (d)
712 }
713
714 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
715 if (prev != mem) {
716 // Found an arraycopy but it doesn't affect that load
717 continue;
718 }
719 // Found an arraycopy that may affect that load
720 return mem;
721 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
722 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
723 if (mem->is_Proj() && mem->in(0)->is_Call()) {
724 // ArrayCopyNodes processed here as well.
725 CallNode *call = mem->in(0)->as_Call();
726 if (!call->may_modify(addr_t, phase)) {
727 mem = call->in(TypeFunc::Memory);
728 continue; // (a) advance through independent call memory
729 }
730 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
731 ArrayCopyNode* ac = NULL;
732 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
733 break;
734 }
735 mem = mem->in(0)->in(TypeFunc::Memory);
736 continue; // (a) advance through independent MemBar memory
737 } else if (mem->is_ClearArray()) {
738 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
739 // (the call updated 'mem' value)
740 continue; // (a) advance through independent allocation memory
741 } else {
742 // Can not bypass initialization of the instance
743 // we are looking for.
744 return mem;
745 }
746 } else if (mem->is_MergeMem()) {
747 int alias_idx = phase->C->get_alias_index(adr_type());
748 mem = mem->as_MergeMem()->memory_at(alias_idx);
749 continue; // (a) advance through independent MergeMem memory
750 }
751 }
752
753 // Unless there is an explicit 'continue', we must bail out here,
754 // because 'mem' is an inscrutable memory state (e.g., a call).
755 break;
756 }
757
758 return NULL; // bail out
759 }
760
761 //----------------------calculate_adr_type-------------------------------------
762 // Helper function. Notices when the given type of address hits top or bottom.
763 // Also, asserts a cross-check of the type against the expected address type.
764 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
765 if (t == Type::TOP) return NULL; // does not touch memory any more?
766 #ifdef PRODUCT
767 cross_check = NULL;
768 #else
769 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
770 #endif
771 const TypePtr* tp = t->isa_ptr();
772 if (tp == NULL) {
773 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
774 return TypePtr::BOTTOM; // touches lots of memory
775 } else {
776 #ifdef ASSERT
777 // %%%% [phh] We don't check the alias index if cross_check is
778 // TypeRawPtr::BOTTOM. Needs to be investigated.
779 if (cross_check != NULL &&
780 cross_check != TypePtr::BOTTOM &&
781 cross_check != TypeRawPtr::BOTTOM) {
782 // Recheck the alias index, to see if it has changed (due to a bug).
783 Compile* C = Compile::current();
784 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
785 "must stay in the original alias category");
786 // The type of the address must be contained in the adr_type,
787 // disregarding "null"-ness.
788 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
789 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
790 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
791 "real address must not escape from expected memory type");
792 }
793 #endif
794 return tp;
795 }
796 }
797
798 //=============================================================================
799 // Should LoadNode::Ideal() attempt to remove control edges?
800 bool LoadNode::can_remove_control() const {
801 return true;
802 }
803 uint LoadNode::size_of() const { return sizeof(*this); }
804 uint LoadNode::cmp( const Node &n ) const
805 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
806 const Type *LoadNode::bottom_type() const { return _type; }
807 uint LoadNode::ideal_reg() const {
808 return _type->ideal_reg();
809 }
810
811 #ifndef PRODUCT
812 void LoadNode::dump_spec(outputStream *st) const {
813 MemNode::dump_spec(st);
814 if( !Verbose && !WizardMode ) {
815 // standard dump does this in Verbose and WizardMode
816 st->print(" #"); _type->dump_on(st);
817 }
818 if (!depends_only_on_test()) {
819 st->print(" (does not depend only on test)");
820 }
821 }
822 #endif
823
824 #ifdef ASSERT
825 //----------------------------is_immutable_value-------------------------------
826 // Helper function to allow a raw load without control edge for some cases
827 bool LoadNode::is_immutable_value(Node* adr) {
828 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
829 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
830 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
831 in_bytes(JavaThread::osthread_offset())));
832 }
833 #endif
834
835 //----------------------------LoadNode::make-----------------------------------
836 // Polymorphic factory method:
837 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
838 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
839 Compile* C = gvn.C;
840
841 // sanity check the alias category against the created node type
842 assert(!(adr_type->isa_oopptr() &&
843 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
844 "use LoadKlassNode instead");
845 assert(!(adr_type->isa_aryptr() &&
846 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
847 "use LoadRangeNode instead");
848 // Check control edge of raw loads
849 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
850 // oop will be recorded in oop map if load crosses safepoint
851 rt->isa_oopptr() || is_immutable_value(adr),
852 "raw memory operations should have control edge");
853 LoadNode* load = NULL;
854 switch (bt) {
855 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
856 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
857 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
858 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
859 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
860 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
861 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
862 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
863 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
864 case T_OBJECT:
865 #ifdef _LP64
866 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
867 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
868 } else
869 #endif
870 {
871 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
872 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
873 }
874 break;
875 default:
876 ShouldNotReachHere();
877 break;
878 }
879 assert(load != NULL, "LoadNode should have been created");
880 if (unaligned) {
881 load->set_unaligned_access();
882 }
883 if (mismatched) {
884 load->set_mismatched_access();
885 }
886 if (unsafe) {
887 load->set_unsafe_access();
888 }
889 if (load->Opcode() == Op_LoadN) {
890 Node* ld = gvn.transform(load);
891 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
892 }
893
894 return load;
895 }
896
897 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
898 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
899 bool require_atomic = true;
900 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
901 if (unaligned) {
902 load->set_unaligned_access();
903 }
904 if (mismatched) {
905 load->set_mismatched_access();
906 }
907 if (unsafe) {
908 load->set_unsafe_access();
909 }
910 return load;
911 }
912
913 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
914 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
915 bool require_atomic = true;
916 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
917 if (unaligned) {
918 load->set_unaligned_access();
919 }
920 if (mismatched) {
921 load->set_mismatched_access();
922 }
923 if (unsafe) {
924 load->set_unsafe_access();
925 }
926 return load;
927 }
928
929
930
931 //------------------------------hash-------------------------------------------
932 uint LoadNode::hash() const {
933 // unroll addition of interesting fields
934 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
935 }
936
937 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
938 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
939 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
940 bool is_stable_ary = FoldStableValues &&
941 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
942 tp->isa_aryptr()->is_stable();
943
944 return (eliminate_boxing && non_volatile) || is_stable_ary;
945 }
946
947 return false;
948 }
949
950 // Is the value loaded previously stored by an arraycopy? If so return
951 // a load node that reads from the source array so we may be able to
952 // optimize out the ArrayCopy node later.
953 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
954 #if INCLUDE_ZGC
955 if (UseZGC) {
956 if (bottom_type()->make_oopptr() != NULL) {
957 return NULL;
958 }
959 }
960 #endif
961
962 Node* ld_adr = in(MemNode::Address);
963 intptr_t ld_off = 0;
964 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
965 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
966 if (ac != NULL) {
967 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
968
969 Node* mem = ac->in(TypeFunc::Memory);
970 Node* ctl = ac->in(0);
971 Node* src = ac->in(ArrayCopyNode::Src);
972
973 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
974 return NULL;
975 }
976
977 LoadNode* ld = clone()->as_Load();
978 Node* addp = in(MemNode::Address)->clone();
979 if (ac->as_ArrayCopy()->is_clonebasic()) {
980 assert(ld_alloc != NULL, "need an alloc");
981 assert(addp->is_AddP(), "address must be addp");
982 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
983 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
984 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
985 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
986 } else {
987 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
988 ac->as_ArrayCopy()->is_copyof_validated() ||
989 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
990 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
991 addp->set_req(AddPNode::Base, src);
992 addp->set_req(AddPNode::Address, src);
993
994 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
995 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
996 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
997 uint shift = exact_log2(type2aelembytes(ary_elem));
998
999 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1000 #ifdef _LP64
1001 diff = phase->transform(new ConvI2LNode(diff));
1002 #endif
1003 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1004
1005 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1006 addp->set_req(AddPNode::Offset, offset);
1007 }
1008 addp = phase->transform(addp);
1009 #ifdef ASSERT
1010 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1011 ld->_adr_type = adr_type;
1012 #endif
1013 ld->set_req(MemNode::Address, addp);
1014 ld->set_req(0, ctl);
1015 ld->set_req(MemNode::Memory, mem);
1016 // load depends on the tests that validate the arraycopy
1017 ld->_control_dependency = Pinned;
1018 return ld;
1019 }
1020 return NULL;
1021 }
1022
1023
1024 //---------------------------can_see_stored_value------------------------------
1025 // This routine exists to make sure this set of tests is done the same
1026 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1027 // will change the graph shape in a way which makes memory alive twice at the
1028 // same time (uses the Oracle model of aliasing), then some
1029 // LoadXNode::Identity will fold things back to the equivalence-class model
1030 // of aliasing.
1031 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1032 Node* ld_adr = in(MemNode::Address);
1033 intptr_t ld_off = 0;
1034 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1035 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1036 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1037 // This is more general than load from boxing objects.
1038 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1039 uint alias_idx = atp->index();
1040 bool final = !atp->is_rewritable();
1041 Node* result = NULL;
1042 Node* current = st;
1043 // Skip through chains of MemBarNodes checking the MergeMems for
1044 // new states for the slice of this load. Stop once any other
1045 // kind of node is encountered. Loads from final memory can skip
1046 // through any kind of MemBar but normal loads shouldn't skip
1047 // through MemBarAcquire since the could allow them to move out of
1048 // a synchronized region.
1049 while (current->is_Proj()) {
1050 int opc = current->in(0)->Opcode();
1051 if ((final && (opc == Op_MemBarAcquire ||
1052 opc == Op_MemBarAcquireLock ||
1053 opc == Op_LoadFence)) ||
1054 opc == Op_MemBarRelease ||
1055 opc == Op_StoreFence ||
1056 opc == Op_MemBarReleaseLock ||
1057 opc == Op_MemBarStoreStore ||
1058 opc == Op_MemBarCPUOrder) {
1059 Node* mem = current->in(0)->in(TypeFunc::Memory);
1060 if (mem->is_MergeMem()) {
1061 MergeMemNode* merge = mem->as_MergeMem();
1062 Node* new_st = merge->memory_at(alias_idx);
1063 if (new_st == merge->base_memory()) {
1064 // Keep searching
1065 current = new_st;
1066 continue;
1067 }
1068 // Save the new memory state for the slice and fall through
1069 // to exit.
1070 result = new_st;
1071 }
1072 }
1073 break;
1074 }
1075 if (result != NULL) {
1076 st = result;
1077 }
1078 }
1079
1080 // Loop around twice in the case Load -> Initialize -> Store.
1081 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1082 for (int trip = 0; trip <= 1; trip++) {
1083
1084 if (st->is_Store()) {
1085 Node* st_adr = st->in(MemNode::Address);
1086 if (!phase->eqv(st_adr, ld_adr)) {
1087 // Try harder before giving up... Match raw and non-raw pointers.
1088 intptr_t st_off = 0;
1089 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1090 if (alloc == NULL) return NULL;
1091 if (alloc != ld_alloc) return NULL;
1092 if (ld_off != st_off) return NULL;
1093 // At this point we have proven something like this setup:
1094 // A = Allocate(...)
1095 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1096 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1097 // (Actually, we haven't yet proven the Q's are the same.)
1098 // In other words, we are loading from a casted version of
1099 // the same pointer-and-offset that we stored to.
1100 // Thus, we are able to replace L by V.
1101 }
1102 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1103 if (store_Opcode() != st->Opcode())
1104 return NULL;
1105 return st->in(MemNode::ValueIn);
1106 }
1107
1108 // A load from a freshly-created object always returns zero.
1109 // (This can happen after LoadNode::Ideal resets the load's memory input
1110 // to find_captured_store, which returned InitializeNode::zero_memory.)
1111 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1112 (st->in(0) == ld_alloc) &&
1113 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1114 // return a zero value for the load's basic type
1115 // (This is one of the few places where a generic PhaseTransform
1116 // can create new nodes. Think of it as lazily manifesting
1117 // virtually pre-existing constants.)
1118 if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == NULL) {
1119 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1120 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1121 // by the ArrayCopyNode.
1122 return phase->zerocon(memory_type());
1123 }
1124 }
1125
1126 // A load from an initialization barrier can match a captured store.
1127 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1128 InitializeNode* init = st->in(0)->as_Initialize();
1129 AllocateNode* alloc = init->allocation();
1130 if ((alloc != NULL) && (alloc == ld_alloc)) {
1131 // examine a captured store value
1132 st = init->find_captured_store(ld_off, memory_size(), phase);
1133 if (st != NULL) {
1134 continue; // take one more trip around
1135 }
1136 }
1137 }
1138
1139 // Load boxed value from result of valueOf() call is input parameter.
1140 if (this->is_Load() && ld_adr->is_AddP() &&
1141 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1142 intptr_t ignore = 0;
1143 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1144 #if INCLUDE_SHENANDOAHGC
1145 if (UseShenandoahGC) {
1146 base = ((ShenandoahBarrierSetC2*) BarrierSet::barrier_set()->barrier_set_c2())->step_over_gc_barrier(base);
1147 }
1148 #endif
1149 if (base != NULL && base->is_Proj() &&
1150 base->as_Proj()->_con == TypeFunc::Parms &&
1151 base->in(0)->is_CallStaticJava() &&
1152 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1153 return base->in(0)->in(TypeFunc::Parms);
1154 }
1155 }
1156
1157 break;
1158 }
1159
1160 return NULL;
1161 }
1162
1163 //----------------------is_instance_field_load_with_local_phi------------------
1164 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1165 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1166 in(Address)->is_AddP() ) {
1167 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1168 // Only instances and boxed values.
1169 if( t_oop != NULL &&
1170 (t_oop->is_ptr_to_boxed_value() ||
1171 t_oop->is_known_instance_field()) &&
1172 t_oop->offset() != Type::OffsetBot &&
1173 t_oop->offset() != Type::OffsetTop) {
1174 return true;
1175 }
1176 }
1177 return false;
1178 }
1179
1180 //------------------------------Identity---------------------------------------
1181 // Loads are identity if previous store is to same address
1182 Node* LoadNode::Identity(PhaseGVN* phase) {
1183 // If the previous store-maker is the right kind of Store, and the store is
1184 // to the same address, then we are equal to the value stored.
1185 Node* mem = in(Memory);
1186 Node* value = can_see_stored_value(mem, phase);
1187 if( value ) {
1188 // byte, short & char stores truncate naturally.
1189 // A load has to load the truncated value which requires
1190 // some sort of masking operation and that requires an
1191 // Ideal call instead of an Identity call.
1192 if (memory_size() < BytesPerInt) {
1193 // If the input to the store does not fit with the load's result type,
1194 // it must be truncated via an Ideal call.
1195 if (!phase->type(value)->higher_equal(phase->type(this)))
1196 return this;
1197 }
1198 // (This works even when value is a Con, but LoadNode::Value
1199 // usually runs first, producing the singleton type of the Con.)
1200 return value;
1201 }
1202
1203 // Search for an existing data phi which was generated before for the same
1204 // instance's field to avoid infinite generation of phis in a loop.
1205 Node *region = mem->in(0);
1206 if (is_instance_field_load_with_local_phi(region)) {
1207 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1208 int this_index = phase->C->get_alias_index(addr_t);
1209 int this_offset = addr_t->offset();
1210 int this_iid = addr_t->instance_id();
1211 if (!addr_t->is_known_instance() &&
1212 addr_t->is_ptr_to_boxed_value()) {
1213 // Use _idx of address base (could be Phi node) for boxed values.
1214 intptr_t ignore = 0;
1215 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1216 if (base == NULL) {
1217 return this;
1218 }
1219 this_iid = base->_idx;
1220 }
1221 const Type* this_type = bottom_type();
1222 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1223 Node* phi = region->fast_out(i);
1224 if (phi->is_Phi() && phi != mem &&
1225 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1226 return phi;
1227 }
1228 }
1229 }
1230
1231 return this;
1232 }
1233
1234 // Construct an equivalent unsigned load.
1235 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1236 BasicType bt = T_ILLEGAL;
1237 const Type* rt = NULL;
1238 switch (Opcode()) {
1239 case Op_LoadUB: return this;
1240 case Op_LoadUS: return this;
1241 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1242 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1243 default:
1244 assert(false, "no unsigned variant: %s", Name());
1245 return NULL;
1246 }
1247 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1248 raw_adr_type(), rt, bt, _mo, _control_dependency,
1249 is_unaligned_access(), is_mismatched_access());
1250 }
1251
1252 // Construct an equivalent signed load.
1253 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1254 BasicType bt = T_ILLEGAL;
1255 const Type* rt = NULL;
1256 switch (Opcode()) {
1257 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1258 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1259 case Op_LoadB: // fall through
1260 case Op_LoadS: // fall through
1261 case Op_LoadI: // fall through
1262 case Op_LoadL: return this;
1263 default:
1264 assert(false, "no signed variant: %s", Name());
1265 return NULL;
1266 }
1267 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1268 raw_adr_type(), rt, bt, _mo, _control_dependency,
1269 is_unaligned_access(), is_mismatched_access());
1270 }
1271
1272 // We're loading from an object which has autobox behaviour.
1273 // If this object is result of a valueOf call we'll have a phi
1274 // merging a newly allocated object and a load from the cache.
1275 // We want to replace this load with the original incoming
1276 // argument to the valueOf call.
1277 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1278 assert(phase->C->eliminate_boxing(), "sanity");
1279 intptr_t ignore = 0;
1280 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1281 if ((base == NULL) || base->is_Phi()) {
1282 // Push the loads from the phi that comes from valueOf up
1283 // through it to allow elimination of the loads and the recovery
1284 // of the original value. It is done in split_through_phi().
1285 return NULL;
1286 } else if (base->is_Load() ||
1287 (base->is_DecodeN() && base->in(1)->is_Load())) {
1288 // Eliminate the load of boxed value for integer types from the cache
1289 // array by deriving the value from the index into the array.
1290 // Capture the offset of the load and then reverse the computation.
1291
1292 // Get LoadN node which loads a boxing object from 'cache' array.
1293 if (base->is_DecodeN()) {
1294 base = base->in(1);
1295 }
1296 if (!base->in(Address)->is_AddP()) {
1297 return NULL; // Complex address
1298 }
1299 AddPNode* address = base->in(Address)->as_AddP();
1300 Node* cache_base = address->in(AddPNode::Base);
1301 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1302 // Get ConP node which is static 'cache' field.
1303 cache_base = cache_base->in(1);
1304 }
1305 if ((cache_base != NULL) && cache_base->is_Con()) {
1306 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1307 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1308 Node* elements[4];
1309 int shift = exact_log2(type2aelembytes(T_OBJECT));
1310 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1311 if (count > 0 && elements[0]->is_Con() &&
1312 (count == 1 ||
1313 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1314 elements[1]->in(2) == phase->intcon(shift)))) {
1315 ciObjArray* array = base_type->const_oop()->as_obj_array();
1316 // Fetch the box object cache[0] at the base of the array and get its value
1317 ciInstance* box = array->obj_at(0)->as_instance();
1318 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1319 assert(ik->is_box_klass(), "sanity");
1320 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1321 if (ik->nof_nonstatic_fields() == 1) {
1322 // This should be true nonstatic_field_at requires calling
1323 // nof_nonstatic_fields so check it anyway
1324 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1325 BasicType bt = c.basic_type();
1326 // Only integer types have boxing cache.
1327 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1328 bt == T_BYTE || bt == T_SHORT ||
1329 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1330 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1331 if (cache_low != (int)cache_low) {
1332 return NULL; // should not happen since cache is array indexed by value
1333 }
1334 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1335 if (offset != (int)offset) {
1336 return NULL; // should not happen since cache is array indexed by value
1337 }
1338 // Add up all the offsets making of the address of the load
1339 Node* result = elements[0];
1340 for (int i = 1; i < count; i++) {
1341 result = phase->transform(new AddXNode(result, elements[i]));
1342 }
1343 // Remove the constant offset from the address and then
1344 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1345 // remove the scaling of the offset to recover the original index.
1346 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1347 // Peel the shift off directly but wrap it in a dummy node
1348 // since Ideal can't return existing nodes
1349 result = new RShiftXNode(result->in(1), phase->intcon(0));
1350 } else if (result->is_Add() && result->in(2)->is_Con() &&
1351 result->in(1)->Opcode() == Op_LShiftX &&
1352 result->in(1)->in(2) == phase->intcon(shift)) {
1353 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1354 // but for boxing cache access we know that X<<Z will not overflow
1355 // (there is range check) so we do this optimizatrion by hand here.
1356 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1357 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1358 } else {
1359 result = new RShiftXNode(result, phase->intcon(shift));
1360 }
1361 #ifdef _LP64
1362 if (bt != T_LONG) {
1363 result = new ConvL2INode(phase->transform(result));
1364 }
1365 #else
1366 if (bt == T_LONG) {
1367 result = new ConvI2LNode(phase->transform(result));
1368 }
1369 #endif
1370 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1371 // Need to preserve unboxing load type if it is unsigned.
1372 switch(this->Opcode()) {
1373 case Op_LoadUB:
1374 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1375 break;
1376 case Op_LoadUS:
1377 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1378 break;
1379 }
1380 return result;
1381 }
1382 }
1383 }
1384 }
1385 }
1386 return NULL;
1387 }
1388
1389 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1390 Node* region = phi->in(0);
1391 if (region == NULL) {
1392 return false; // Wait stable graph
1393 }
1394 uint cnt = phi->req();
1395 for (uint i = 1; i < cnt; i++) {
1396 Node* rc = region->in(i);
1397 if (rc == NULL || phase->type(rc) == Type::TOP)
1398 return false; // Wait stable graph
1399 Node* in = phi->in(i);
1400 if (in == NULL || phase->type(in) == Type::TOP)
1401 return false; // Wait stable graph
1402 }
1403 return true;
1404 }
1405 //------------------------------split_through_phi------------------------------
1406 // Split instance or boxed field load through Phi.
1407 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1408 Node* mem = in(Memory);
1409 Node* address = in(Address);
1410 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1411
1412 assert((t_oop != NULL) &&
1413 (t_oop->is_known_instance_field() ||
1414 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1415
1416 Compile* C = phase->C;
1417 intptr_t ignore = 0;
1418 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1419 bool base_is_phi = (base != NULL) && base->is_Phi();
1420 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1421 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1422 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1423
1424 if (!((mem->is_Phi() || base_is_phi) &&
1425 (load_boxed_values || t_oop->is_known_instance_field()))) {
1426 return NULL; // memory is not Phi
1427 }
1428
1429 if (mem->is_Phi()) {
1430 if (!stable_phi(mem->as_Phi(), phase)) {
1431 return NULL; // Wait stable graph
1432 }
1433 uint cnt = mem->req();
1434 // Check for loop invariant memory.
1435 if (cnt == 3) {
1436 for (uint i = 1; i < cnt; i++) {
1437 Node* in = mem->in(i);
1438 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1439 if (m == mem) {
1440 if (i == 1) {
1441 // if the first edge was a loop, check second edge too.
1442 // If both are replaceable - we are in an infinite loop
1443 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1444 if (n == mem) {
1445 break;
1446 }
1447 }
1448 set_req(Memory, mem->in(cnt - i));
1449 return this; // made change
1450 }
1451 }
1452 }
1453 }
1454 if (base_is_phi) {
1455 if (!stable_phi(base->as_Phi(), phase)) {
1456 return NULL; // Wait stable graph
1457 }
1458 uint cnt = base->req();
1459 // Check for loop invariant memory.
1460 if (cnt == 3) {
1461 for (uint i = 1; i < cnt; i++) {
1462 if (base->in(i) == base) {
1463 return NULL; // Wait stable graph
1464 }
1465 }
1466 }
1467 }
1468
1469 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1470
1471 // Split through Phi (see original code in loopopts.cpp).
1472 assert(C->have_alias_type(t_oop), "instance should have alias type");
1473
1474 // Do nothing here if Identity will find a value
1475 // (to avoid infinite chain of value phis generation).
1476 if (!phase->eqv(this, phase->apply_identity(this)))
1477 return NULL;
1478
1479 // Select Region to split through.
1480 Node* region;
1481 if (!base_is_phi) {
1482 assert(mem->is_Phi(), "sanity");
1483 region = mem->in(0);
1484 // Skip if the region dominates some control edge of the address.
1485 if (!MemNode::all_controls_dominate(address, region))
1486 return NULL;
1487 } else if (!mem->is_Phi()) {
1488 assert(base_is_phi, "sanity");
1489 region = base->in(0);
1490 // Skip if the region dominates some control edge of the memory.
1491 if (!MemNode::all_controls_dominate(mem, region))
1492 return NULL;
1493 } else if (base->in(0) != mem->in(0)) {
1494 assert(base_is_phi && mem->is_Phi(), "sanity");
1495 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1496 region = base->in(0);
1497 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1498 region = mem->in(0);
1499 } else {
1500 return NULL; // complex graph
1501 }
1502 } else {
1503 assert(base->in(0) == mem->in(0), "sanity");
1504 region = mem->in(0);
1505 }
1506
1507 const Type* this_type = this->bottom_type();
1508 int this_index = C->get_alias_index(t_oop);
1509 int this_offset = t_oop->offset();
1510 int this_iid = t_oop->instance_id();
1511 if (!t_oop->is_known_instance() && load_boxed_values) {
1512 // Use _idx of address base for boxed values.
1513 this_iid = base->_idx;
1514 }
1515 PhaseIterGVN* igvn = phase->is_IterGVN();
1516 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1517 for (uint i = 1; i < region->req(); i++) {
1518 Node* x;
1519 Node* the_clone = NULL;
1520 Node* in = region->in(i);
1521 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1522 in != NULL && in->is_OuterStripMinedLoop()) {
1523 // No node should go in the outer strip mined loop
1524 in = in->in(LoopNode::EntryControl);
1525 }
1526 if (in == NULL || in == C->top()) {
1527 x = C->top(); // Dead path? Use a dead data op
1528 } else {
1529 x = this->clone(); // Else clone up the data op
1530 the_clone = x; // Remember for possible deletion.
1531 // Alter data node to use pre-phi inputs
1532 if (this->in(0) == region) {
1533 x->set_req(0, in);
1534 } else {
1535 x->set_req(0, NULL);
1536 }
1537 if (mem->is_Phi() && (mem->in(0) == region)) {
1538 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1539 }
1540 if (address->is_Phi() && address->in(0) == region) {
1541 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1542 }
1543 if (base_is_phi && (base->in(0) == region)) {
1544 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1545 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1546 x->set_req(Address, adr_x);
1547 }
1548 }
1549 // Check for a 'win' on some paths
1550 const Type *t = x->Value(igvn);
1551
1552 bool singleton = t->singleton();
1553
1554 // See comments in PhaseIdealLoop::split_thru_phi().
1555 if (singleton && t == Type::TOP) {
1556 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1557 }
1558
1559 if (singleton) {
1560 x = igvn->makecon(t);
1561 } else {
1562 // We now call Identity to try to simplify the cloned node.
1563 // Note that some Identity methods call phase->type(this).
1564 // Make sure that the type array is big enough for
1565 // our new node, even though we may throw the node away.
1566 // (This tweaking with igvn only works because x is a new node.)
1567 igvn->set_type(x, t);
1568 // If x is a TypeNode, capture any more-precise type permanently into Node
1569 // otherwise it will be not updated during igvn->transform since
1570 // igvn->type(x) is set to x->Value() already.
1571 x->raise_bottom_type(t);
1572 Node *y = igvn->apply_identity(x);
1573 if (y != x) {
1574 x = y;
1575 } else {
1576 y = igvn->hash_find_insert(x);
1577 if (y) {
1578 x = y;
1579 } else {
1580 // Else x is a new node we are keeping
1581 // We do not need register_new_node_with_optimizer
1582 // because set_type has already been called.
1583 igvn->_worklist.push(x);
1584 }
1585 }
1586 }
1587 if (x != the_clone && the_clone != NULL) {
1588 igvn->remove_dead_node(the_clone);
1589 }
1590 phi->set_req(i, x);
1591 }
1592 // Record Phi
1593 igvn->register_new_node_with_optimizer(phi);
1594 return phi;
1595 }
1596
1597 //------------------------------Ideal------------------------------------------
1598 // If the load is from Field memory and the pointer is non-null, it might be possible to
1599 // zero out the control input.
1600 // If the offset is constant and the base is an object allocation,
1601 // try to hook me up to the exact initializing store.
1602 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1603 Node* p = MemNode::Ideal_common(phase, can_reshape);
1604 if (p) return (p == NodeSentinel) ? NULL : p;
1605
1606 Node* ctrl = in(MemNode::Control);
1607 Node* address = in(MemNode::Address);
1608 bool progress = false;
1609
1610 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1611 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1612
1613 // Skip up past a SafePoint control. Cannot do this for Stores because
1614 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1615 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1616 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1617 !addr_mark ) {
1618 ctrl = ctrl->in(0);
1619 set_req(MemNode::Control,ctrl);
1620 progress = true;
1621 }
1622
1623 intptr_t ignore = 0;
1624 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1625 if (base != NULL
1626 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1627 // Check for useless control edge in some common special cases
1628 if (in(MemNode::Control) != NULL
1629 && can_remove_control()
1630 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1631 && all_controls_dominate(base, phase->C->start())) {
1632 // A method-invariant, non-null address (constant or 'this' argument).
1633 set_req(MemNode::Control, NULL);
1634 progress = true;
1635 }
1636 }
1637
1638 Node* mem = in(MemNode::Memory);
1639 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1640
1641 if (can_reshape && (addr_t != NULL)) {
1642 // try to optimize our memory input
1643 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1644 if (opt_mem != mem) {
1645 set_req(MemNode::Memory, opt_mem);
1646 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1647 return this;
1648 }
1649 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1650 if ((t_oop != NULL) &&
1651 (t_oop->is_known_instance_field() ||
1652 t_oop->is_ptr_to_boxed_value())) {
1653 PhaseIterGVN *igvn = phase->is_IterGVN();
1654 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1655 // Delay this transformation until memory Phi is processed.
1656 phase->is_IterGVN()->_worklist.push(this);
1657 return NULL;
1658 }
1659 // Split instance field load through Phi.
1660 Node* result = split_through_phi(phase);
1661 if (result != NULL) return result;
1662
1663 if (t_oop->is_ptr_to_boxed_value()) {
1664 Node* result = eliminate_autobox(phase);
1665 if (result != NULL) return result;
1666 }
1667 }
1668 }
1669
1670 // Is there a dominating load that loads the same value? Leave
1671 // anything that is not a load of a field/array element (like
1672 // barriers etc.) alone
1673 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1674 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1675 Node *use = mem->fast_out(i);
1676 if (use != this &&
1677 use->Opcode() == Opcode() &&
1678 use->in(0) != NULL &&
1679 use->in(0) != in(0) &&
1680 use->in(Address) == in(Address)) {
1681 Node* ctl = in(0);
1682 for (int i = 0; i < 10 && ctl != NULL; i++) {
1683 ctl = IfNode::up_one_dom(ctl);
1684 if (ctl == use->in(0)) {
1685 set_req(0, use->in(0));
1686 return this;
1687 }
1688 }
1689 }
1690 }
1691 }
1692
1693 // Check for prior store with a different base or offset; make Load
1694 // independent. Skip through any number of them. Bail out if the stores
1695 // are in an endless dead cycle and report no progress. This is a key
1696 // transform for Reflection. However, if after skipping through the Stores
1697 // we can't then fold up against a prior store do NOT do the transform as
1698 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1699 // array memory alive twice: once for the hoisted Load and again after the
1700 // bypassed Store. This situation only works if EVERYBODY who does
1701 // anti-dependence work knows how to bypass. I.e. we need all
1702 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1703 // the alias index stuff. So instead, peek through Stores and IFF we can
1704 // fold up, do so.
1705 Node* prev_mem = find_previous_store(phase);
1706 if (prev_mem != NULL) {
1707 Node* value = can_see_arraycopy_value(prev_mem, phase);
1708 if (value != NULL) {
1709 return value;
1710 }
1711 }
1712 // Steps (a), (b): Walk past independent stores to find an exact match.
1713 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1714 // (c) See if we can fold up on the spot, but don't fold up here.
1715 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1716 // just return a prior value, which is done by Identity calls.
1717 if (can_see_stored_value(prev_mem, phase)) {
1718 // Make ready for step (d):
1719 set_req(MemNode::Memory, prev_mem);
1720 return this;
1721 }
1722 }
1723
1724 return progress ? this : NULL;
1725 }
1726
1727 // Helper to recognize certain Klass fields which are invariant across
1728 // some group of array types (e.g., int[] or all T[] where T < Object).
1729 const Type*
1730 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1731 ciKlass* klass) const {
1732 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1733 // The field is Klass::_modifier_flags. Return its (constant) value.
1734 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1735 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1736 return TypeInt::make(klass->modifier_flags());
1737 }
1738 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1739 // The field is Klass::_access_flags. Return its (constant) value.
1740 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1741 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1742 return TypeInt::make(klass->access_flags());
1743 }
1744 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1745 // The field is Klass::_layout_helper. Return its constant value if known.
1746 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1747 return TypeInt::make(klass->layout_helper());
1748 }
1749
1750 // No match.
1751 return NULL;
1752 }
1753
1754 //------------------------------Value-----------------------------------------
1755 const Type* LoadNode::Value(PhaseGVN* phase) const {
1756 // Either input is TOP ==> the result is TOP
1757 Node* mem = in(MemNode::Memory);
1758 const Type *t1 = phase->type(mem);
1759 if (t1 == Type::TOP) return Type::TOP;
1760 Node* adr = in(MemNode::Address);
1761 const TypePtr* tp = phase->type(adr)->isa_ptr();
1762 if (tp == NULL || tp->empty()) return Type::TOP;
1763 int off = tp->offset();
1764 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1765 Compile* C = phase->C;
1766
1767 // Try to guess loaded type from pointer type
1768 if (tp->isa_aryptr()) {
1769 const TypeAryPtr* ary = tp->is_aryptr();
1770 const Type* t = ary->elem();
1771
1772 // Determine whether the reference is beyond the header or not, by comparing
1773 // the offset against the offset of the start of the array's data.
1774 // Different array types begin at slightly different offsets (12 vs. 16).
1775 // We choose T_BYTE as an example base type that is least restrictive
1776 // as to alignment, which will therefore produce the smallest
1777 // possible base offset.
1778 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1779 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1780
1781 // Try to constant-fold a stable array element.
1782 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1783 // Make sure the reference is not into the header and the offset is constant
1784 ciObject* aobj = ary->const_oop();
1785 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1786 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1787 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1788 stable_dimension,
1789 memory_type(), is_unsigned());
1790 if (con_type != NULL) {
1791 return con_type;
1792 }
1793 }
1794 }
1795
1796 // Don't do this for integer types. There is only potential profit if
1797 // the element type t is lower than _type; that is, for int types, if _type is
1798 // more restrictive than t. This only happens here if one is short and the other
1799 // char (both 16 bits), and in those cases we've made an intentional decision
1800 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1801 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1802 //
1803 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1804 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1805 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1806 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1807 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1808 // In fact, that could have been the original type of p1, and p1 could have
1809 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1810 // expression (LShiftL quux 3) independently optimized to the constant 8.
1811 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1812 && (_type->isa_vect() == NULL)
1813 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1814 // t might actually be lower than _type, if _type is a unique
1815 // concrete subclass of abstract class t.
1816 if (off_beyond_header) { // is the offset beyond the header?
1817 const Type* jt = t->join_speculative(_type);
1818 // In any case, do not allow the join, per se, to empty out the type.
1819 if (jt->empty() && !t->empty()) {
1820 // This can happen if a interface-typed array narrows to a class type.
1821 jt = _type;
1822 }
1823 #ifdef ASSERT
1824 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1825 // The pointers in the autobox arrays are always non-null
1826 Node* base = adr->in(AddPNode::Base);
1827 if ((base != NULL) && base->is_DecodeN()) {
1828 // Get LoadN node which loads IntegerCache.cache field
1829 base = base->in(1);
1830 }
1831 if ((base != NULL) && base->is_Con()) {
1832 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1833 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1834 // It could be narrow oop
1835 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1836 }
1837 }
1838 }
1839 #endif
1840 return jt;
1841 }
1842 }
1843 } else if (tp->base() == Type::InstPtr) {
1844 assert( off != Type::OffsetBot ||
1845 // arrays can be cast to Objects
1846 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1847 // unsafe field access may not have a constant offset
1848 C->has_unsafe_access(),
1849 "Field accesses must be precise" );
1850 // For oop loads, we expect the _type to be precise.
1851
1852 // Optimize loads from constant fields.
1853 const TypeInstPtr* tinst = tp->is_instptr();
1854 ciObject* const_oop = tinst->const_oop();
1855 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1856 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1857 if (con_type != NULL) {
1858 return con_type;
1859 }
1860 }
1861 } else if (tp->base() == Type::KlassPtr) {
1862 assert( off != Type::OffsetBot ||
1863 // arrays can be cast to Objects
1864 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1865 // also allow array-loading from the primary supertype
1866 // array during subtype checks
1867 Opcode() == Op_LoadKlass,
1868 "Field accesses must be precise" );
1869 // For klass/static loads, we expect the _type to be precise
1870 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
1871 /* With mirrors being an indirect in the Klass*
1872 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1873 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1874 *
1875 * So check the type and klass of the node before the LoadP.
1876 */
1877 Node* adr2 = adr->in(MemNode::Address);
1878 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1879 if (tkls != NULL && !StressReflectiveCode) {
1880 ciKlass* klass = tkls->klass();
1881 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1882 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1883 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1884 return TypeInstPtr::make(klass->java_mirror());
1885 }
1886 }
1887 }
1888
1889 const TypeKlassPtr *tkls = tp->isa_klassptr();
1890 if (tkls != NULL && !StressReflectiveCode) {
1891 ciKlass* klass = tkls->klass();
1892 if (klass->is_loaded() && tkls->klass_is_exact()) {
1893 // We are loading a field from a Klass metaobject whose identity
1894 // is known at compile time (the type is "exact" or "precise").
1895 // Check for fields we know are maintained as constants by the VM.
1896 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1897 // The field is Klass::_super_check_offset. Return its (constant) value.
1898 // (Folds up type checking code.)
1899 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1900 return TypeInt::make(klass->super_check_offset());
1901 }
1902 // Compute index into primary_supers array
1903 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1904 // Check for overflowing; use unsigned compare to handle the negative case.
1905 if( depth < ciKlass::primary_super_limit() ) {
1906 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1907 // (Folds up type checking code.)
1908 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1909 ciKlass *ss = klass->super_of_depth(depth);
1910 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1911 }
1912 const Type* aift = load_array_final_field(tkls, klass);
1913 if (aift != NULL) return aift;
1914 }
1915
1916 // We can still check if we are loading from the primary_supers array at a
1917 // shallow enough depth. Even though the klass is not exact, entries less
1918 // than or equal to its super depth are correct.
1919 if (klass->is_loaded() ) {
1920 ciType *inner = klass;
1921 while( inner->is_obj_array_klass() )
1922 inner = inner->as_obj_array_klass()->base_element_type();
1923 if( inner->is_instance_klass() &&
1924 !inner->as_instance_klass()->flags().is_interface() ) {
1925 // Compute index into primary_supers array
1926 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1927 // Check for overflowing; use unsigned compare to handle the negative case.
1928 if( depth < ciKlass::primary_super_limit() &&
1929 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1930 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1931 // (Folds up type checking code.)
1932 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1933 ciKlass *ss = klass->super_of_depth(depth);
1934 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1935 }
1936 }
1937 }
1938
1939 // If the type is enough to determine that the thing is not an array,
1940 // we can give the layout_helper a positive interval type.
1941 // This will help short-circuit some reflective code.
1942 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1943 && !klass->is_array_klass() // not directly typed as an array
1944 && !klass->is_interface() // specifically not Serializable & Cloneable
1945 && !klass->is_java_lang_Object() // not the supertype of all T[]
1946 ) {
1947 // Note: When interfaces are reliable, we can narrow the interface
1948 // test to (klass != Serializable && klass != Cloneable).
1949 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1950 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1951 // The key property of this type is that it folds up tests
1952 // for array-ness, since it proves that the layout_helper is positive.
1953 // Thus, a generic value like the basic object layout helper works fine.
1954 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1955 }
1956 }
1957
1958 // If we are loading from a freshly-allocated object, produce a zero,
1959 // if the load is provably beyond the header of the object.
1960 // (Also allow a variable load from a fresh array to produce zero.)
1961 const TypeOopPtr *tinst = tp->isa_oopptr();
1962 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1963 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1964 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1965 Node* value = can_see_stored_value(mem,phase);
1966 if (value != NULL && value->is_Con()) {
1967 assert(value->bottom_type()->higher_equal(_type),"sanity");
1968 return value->bottom_type();
1969 }
1970 }
1971
1972 if (is_instance) {
1973 // If we have an instance type and our memory input is the
1974 // programs's initial memory state, there is no matching store,
1975 // so just return a zero of the appropriate type
1976 Node *mem = in(MemNode::Memory);
1977 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1978 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1979 return Type::get_zero_type(_type->basic_type());
1980 }
1981 }
1982 return _type;
1983 }
1984
1985 //------------------------------match_edge-------------------------------------
1986 // Do we Match on this edge index or not? Match only the address.
1987 uint LoadNode::match_edge(uint idx) const {
1988 return idx == MemNode::Address;
1989 }
1990
1991 //--------------------------LoadBNode::Ideal--------------------------------------
1992 //
1993 // If the previous store is to the same address as this load,
1994 // and the value stored was larger than a byte, replace this load
1995 // with the value stored truncated to a byte. If no truncation is
1996 // needed, the replacement is done in LoadNode::Identity().
1997 //
1998 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1999 Node* mem = in(MemNode::Memory);
2000 Node* value = can_see_stored_value(mem,phase);
2001 if (value != NULL) {
2002 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2003 if (narrow != value) {
2004 return narrow;
2005 }
2006 }
2007 // Identity call will handle the case where truncation is not needed.
2008 return LoadNode::Ideal(phase, can_reshape);
2009 }
2010
2011 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2012 Node* mem = in(MemNode::Memory);
2013 Node* value = can_see_stored_value(mem,phase);
2014 if (value != NULL && value->is_Con() &&
2015 !value->bottom_type()->higher_equal(_type)) {
2016 // If the input to the store does not fit with the load's result type,
2017 // it must be truncated. We can't delay until Ideal call since
2018 // a singleton Value is needed for split_thru_phi optimization.
2019 int con = value->get_int();
2020 return TypeInt::make((con << 24) >> 24);
2021 }
2022 return LoadNode::Value(phase);
2023 }
2024
2025 //--------------------------LoadUBNode::Ideal-------------------------------------
2026 //
2027 // If the previous store is to the same address as this load,
2028 // and the value stored was larger than a byte, replace this load
2029 // with the value stored truncated to a byte. If no truncation is
2030 // needed, the replacement is done in LoadNode::Identity().
2031 //
2032 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2033 Node* mem = in(MemNode::Memory);
2034 Node* value = can_see_stored_value(mem, phase);
2035 if (value != NULL) {
2036 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2037 if (narrow != value) {
2038 return narrow;
2039 }
2040 }
2041 // Identity call will handle the case where truncation is not needed.
2042 return LoadNode::Ideal(phase, can_reshape);
2043 }
2044
2045 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2046 Node* mem = in(MemNode::Memory);
2047 Node* value = can_see_stored_value(mem,phase);
2048 if (value != NULL && value->is_Con() &&
2049 !value->bottom_type()->higher_equal(_type)) {
2050 // If the input to the store does not fit with the load's result type,
2051 // it must be truncated. We can't delay until Ideal call since
2052 // a singleton Value is needed for split_thru_phi optimization.
2053 int con = value->get_int();
2054 return TypeInt::make(con & 0xFF);
2055 }
2056 return LoadNode::Value(phase);
2057 }
2058
2059 //--------------------------LoadUSNode::Ideal-------------------------------------
2060 //
2061 // If the previous store is to the same address as this load,
2062 // and the value stored was larger than a char, replace this load
2063 // with the value stored truncated to a char. If no truncation is
2064 // needed, the replacement is done in LoadNode::Identity().
2065 //
2066 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2067 Node* mem = in(MemNode::Memory);
2068 Node* value = can_see_stored_value(mem,phase);
2069 if (value != NULL) {
2070 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2071 if (narrow != value) {
2072 return narrow;
2073 }
2074 }
2075 // Identity call will handle the case where truncation is not needed.
2076 return LoadNode::Ideal(phase, can_reshape);
2077 }
2078
2079 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2080 Node* mem = in(MemNode::Memory);
2081 Node* value = can_see_stored_value(mem,phase);
2082 if (value != NULL && value->is_Con() &&
2083 !value->bottom_type()->higher_equal(_type)) {
2084 // If the input to the store does not fit with the load's result type,
2085 // it must be truncated. We can't delay until Ideal call since
2086 // a singleton Value is needed for split_thru_phi optimization.
2087 int con = value->get_int();
2088 return TypeInt::make(con & 0xFFFF);
2089 }
2090 return LoadNode::Value(phase);
2091 }
2092
2093 //--------------------------LoadSNode::Ideal--------------------------------------
2094 //
2095 // If the previous store is to the same address as this load,
2096 // and the value stored was larger than a short, replace this load
2097 // with the value stored truncated to a short. If no truncation is
2098 // needed, the replacement is done in LoadNode::Identity().
2099 //
2100 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2101 Node* mem = in(MemNode::Memory);
2102 Node* value = can_see_stored_value(mem,phase);
2103 if (value != NULL) {
2104 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2105 if (narrow != value) {
2106 return narrow;
2107 }
2108 }
2109 // Identity call will handle the case where truncation is not needed.
2110 return LoadNode::Ideal(phase, can_reshape);
2111 }
2112
2113 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2114 Node* mem = in(MemNode::Memory);
2115 Node* value = can_see_stored_value(mem,phase);
2116 if (value != NULL && value->is_Con() &&
2117 !value->bottom_type()->higher_equal(_type)) {
2118 // If the input to the store does not fit with the load's result type,
2119 // it must be truncated. We can't delay until Ideal call since
2120 // a singleton Value is needed for split_thru_phi optimization.
2121 int con = value->get_int();
2122 return TypeInt::make((con << 16) >> 16);
2123 }
2124 return LoadNode::Value(phase);
2125 }
2126
2127 //=============================================================================
2128 //----------------------------LoadKlassNode::make------------------------------
2129 // Polymorphic factory method:
2130 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2131 // sanity check the alias category against the created node type
2132 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2133 assert(adr_type != NULL, "expecting TypeKlassPtr");
2134 #ifdef _LP64
2135 if (adr_type->is_ptr_to_narrowklass()) {
2136 assert(UseCompressedClassPointers, "no compressed klasses");
2137 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2138 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2139 }
2140 #endif
2141 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2142 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2143 }
2144
2145 //------------------------------Value------------------------------------------
2146 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2147 return klass_value_common(phase);
2148 }
2149
2150 // In most cases, LoadKlassNode does not have the control input set. If the control
2151 // input is set, it must not be removed (by LoadNode::Ideal()).
2152 bool LoadKlassNode::can_remove_control() const {
2153 return false;
2154 }
2155
2156 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2157 // Either input is TOP ==> the result is TOP
2158 const Type *t1 = phase->type( in(MemNode::Memory) );
2159 if (t1 == Type::TOP) return Type::TOP;
2160 Node *adr = in(MemNode::Address);
2161 const Type *t2 = phase->type( adr );
2162 if (t2 == Type::TOP) return Type::TOP;
2163 const TypePtr *tp = t2->is_ptr();
2164 if (TypePtr::above_centerline(tp->ptr()) ||
2165 tp->ptr() == TypePtr::Null) return Type::TOP;
2166
2167 // Return a more precise klass, if possible
2168 const TypeInstPtr *tinst = tp->isa_instptr();
2169 if (tinst != NULL) {
2170 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2171 int offset = tinst->offset();
2172 if (ik == phase->C->env()->Class_klass()
2173 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2174 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2175 // We are loading a special hidden field from a Class mirror object,
2176 // the field which points to the VM's Klass metaobject.
2177 ciType* t = tinst->java_mirror_type();
2178 // java_mirror_type returns non-null for compile-time Class constants.
2179 if (t != NULL) {
2180 // constant oop => constant klass
2181 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2182 if (t->is_void()) {
2183 // We cannot create a void array. Since void is a primitive type return null
2184 // klass. Users of this result need to do a null check on the returned klass.
2185 return TypePtr::NULL_PTR;
2186 }
2187 return TypeKlassPtr::make(ciArrayKlass::make(t));
2188 }
2189 if (!t->is_klass()) {
2190 // a primitive Class (e.g., int.class) has NULL for a klass field
2191 return TypePtr::NULL_PTR;
2192 }
2193 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2194 return TypeKlassPtr::make(t->as_klass());
2195 }
2196 // non-constant mirror, so we can't tell what's going on
2197 }
2198 if( !ik->is_loaded() )
2199 return _type; // Bail out if not loaded
2200 if (offset == oopDesc::klass_offset_in_bytes()) {
2201 if (tinst->klass_is_exact()) {
2202 return TypeKlassPtr::make(ik);
2203 }
2204 // See if we can become precise: no subklasses and no interface
2205 // (Note: We need to support verified interfaces.)
2206 if (!ik->is_interface() && !ik->has_subklass()) {
2207 //assert(!UseExactTypes, "this code should be useless with exact types");
2208 // Add a dependence; if any subclass added we need to recompile
2209 if (!ik->is_final()) {
2210 // %%% should use stronger assert_unique_concrete_subtype instead
2211 phase->C->dependencies()->assert_leaf_type(ik);
2212 }
2213 // Return precise klass
2214 return TypeKlassPtr::make(ik);
2215 }
2216
2217 // Return root of possible klass
2218 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2219 }
2220 }
2221
2222 // Check for loading klass from an array
2223 const TypeAryPtr *tary = tp->isa_aryptr();
2224 if( tary != NULL ) {
2225 ciKlass *tary_klass = tary->klass();
2226 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2227 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2228 if (tary->klass_is_exact()) {
2229 return TypeKlassPtr::make(tary_klass);
2230 }
2231 ciArrayKlass *ak = tary->klass()->as_array_klass();
2232 // If the klass is an object array, we defer the question to the
2233 // array component klass.
2234 if( ak->is_obj_array_klass() ) {
2235 assert( ak->is_loaded(), "" );
2236 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2237 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2238 ciInstanceKlass* ik = base_k->as_instance_klass();
2239 // See if we can become precise: no subklasses and no interface
2240 if (!ik->is_interface() && !ik->has_subklass()) {
2241 //assert(!UseExactTypes, "this code should be useless with exact types");
2242 // Add a dependence; if any subclass added we need to recompile
2243 if (!ik->is_final()) {
2244 phase->C->dependencies()->assert_leaf_type(ik);
2245 }
2246 // Return precise array klass
2247 return TypeKlassPtr::make(ak);
2248 }
2249 }
2250 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2251 } else { // Found a type-array?
2252 //assert(!UseExactTypes, "this code should be useless with exact types");
2253 assert( ak->is_type_array_klass(), "" );
2254 return TypeKlassPtr::make(ak); // These are always precise
2255 }
2256 }
2257 }
2258
2259 // Check for loading klass from an array klass
2260 const TypeKlassPtr *tkls = tp->isa_klassptr();
2261 if (tkls != NULL && !StressReflectiveCode) {
2262 ciKlass* klass = tkls->klass();
2263 if( !klass->is_loaded() )
2264 return _type; // Bail out if not loaded
2265 if( klass->is_obj_array_klass() &&
2266 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2267 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2268 // // Always returning precise element type is incorrect,
2269 // // e.g., element type could be object and array may contain strings
2270 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2271
2272 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2273 // according to the element type's subclassing.
2274 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2275 }
2276 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2277 tkls->offset() == in_bytes(Klass::super_offset())) {
2278 ciKlass* sup = klass->as_instance_klass()->super();
2279 // The field is Klass::_super. Return its (constant) value.
2280 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2281 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2282 }
2283 }
2284
2285 // Bailout case
2286 return LoadNode::Value(phase);
2287 }
2288
2289 //------------------------------Identity---------------------------------------
2290 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2291 // Also feed through the klass in Allocate(...klass...)._klass.
2292 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2293 return klass_identity_common(phase);
2294 }
2295
2296 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2297 Node* x = LoadNode::Identity(phase);
2298 if (x != this) return x;
2299
2300 // Take apart the address into an oop and and offset.
2301 // Return 'this' if we cannot.
2302 Node* adr = in(MemNode::Address);
2303 intptr_t offset = 0;
2304 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2305 if (base == NULL) return this;
2306 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2307 if (toop == NULL) return this;
2308
2309 // Step over potential GC barrier for OopHandle resolve
2310 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2311 if (bs->is_gc_barrier_node(base)) {
2312 base = bs->step_over_gc_barrier(base);
2313 }
2314
2315 // We can fetch the klass directly through an AllocateNode.
2316 // This works even if the klass is not constant (clone or newArray).
2317 if (offset == oopDesc::klass_offset_in_bytes()) {
2318 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2319 if (allocated_klass != NULL) {
2320 return allocated_klass;
2321 }
2322 }
2323
2324 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2325 // See inline_native_Class_query for occurrences of these patterns.
2326 // Java Example: x.getClass().isAssignableFrom(y)
2327 //
2328 // This improves reflective code, often making the Class
2329 // mirror go completely dead. (Current exception: Class
2330 // mirrors may appear in debug info, but we could clean them out by
2331 // introducing a new debug info operator for Klass.java_mirror).
2332
2333 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2334 && offset == java_lang_Class::klass_offset_in_bytes()) {
2335 if (base->is_Load()) {
2336 Node* base2 = base->in(MemNode::Address);
2337 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2338 Node* adr2 = base2->in(MemNode::Address);
2339 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2340 if (tkls != NULL && !tkls->empty()
2341 && (tkls->klass()->is_instance_klass() ||
2342 tkls->klass()->is_array_klass())
2343 && adr2->is_AddP()
2344 ) {
2345 int mirror_field = in_bytes(Klass::java_mirror_offset());
2346 if (tkls->offset() == mirror_field) {
2347 return adr2->in(AddPNode::Base);
2348 }
2349 }
2350 }
2351 }
2352 }
2353
2354 return this;
2355 }
2356
2357
2358 //------------------------------Value------------------------------------------
2359 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2360 const Type *t = klass_value_common(phase);
2361 if (t == Type::TOP)
2362 return t;
2363
2364 return t->make_narrowklass();
2365 }
2366
2367 //------------------------------Identity---------------------------------------
2368 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2369 // Also feed through the klass in Allocate(...klass...)._klass.
2370 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2371 Node *x = klass_identity_common(phase);
2372
2373 const Type *t = phase->type( x );
2374 if( t == Type::TOP ) return x;
2375 if( t->isa_narrowklass()) return x;
2376 assert (!t->isa_narrowoop(), "no narrow oop here");
2377
2378 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2379 }
2380
2381 //------------------------------Value-----------------------------------------
2382 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2383 // Either input is TOP ==> the result is TOP
2384 const Type *t1 = phase->type( in(MemNode::Memory) );
2385 if( t1 == Type::TOP ) return Type::TOP;
2386 Node *adr = in(MemNode::Address);
2387 const Type *t2 = phase->type( adr );
2388 if( t2 == Type::TOP ) return Type::TOP;
2389 const TypePtr *tp = t2->is_ptr();
2390 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2391 const TypeAryPtr *tap = tp->isa_aryptr();
2392 if( !tap ) return _type;
2393 return tap->size();
2394 }
2395
2396 //-------------------------------Ideal---------------------------------------
2397 // Feed through the length in AllocateArray(...length...)._length.
2398 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2399 Node* p = MemNode::Ideal_common(phase, can_reshape);
2400 if (p) return (p == NodeSentinel) ? NULL : p;
2401
2402 // Take apart the address into an oop and and offset.
2403 // Return 'this' if we cannot.
2404 Node* adr = in(MemNode::Address);
2405 intptr_t offset = 0;
2406 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2407 if (base == NULL) return NULL;
2408 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2409 if (tary == NULL) return NULL;
2410
2411 // We can fetch the length directly through an AllocateArrayNode.
2412 // This works even if the length is not constant (clone or newArray).
2413 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2414 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2415 if (alloc != NULL) {
2416 Node* allocated_length = alloc->Ideal_length();
2417 Node* len = alloc->make_ideal_length(tary, phase);
2418 if (allocated_length != len) {
2419 // New CastII improves on this.
2420 return len;
2421 }
2422 }
2423 }
2424
2425 return NULL;
2426 }
2427
2428 //------------------------------Identity---------------------------------------
2429 // Feed through the length in AllocateArray(...length...)._length.
2430 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2431 Node* x = LoadINode::Identity(phase);
2432 if (x != this) return x;
2433
2434 // Take apart the address into an oop and and offset.
2435 // Return 'this' if we cannot.
2436 Node* adr = in(MemNode::Address);
2437 intptr_t offset = 0;
2438 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2439 if (base == NULL) return this;
2440 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2441 if (tary == NULL) return this;
2442
2443 // We can fetch the length directly through an AllocateArrayNode.
2444 // This works even if the length is not constant (clone or newArray).
2445 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2446 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2447 if (alloc != NULL) {
2448 Node* allocated_length = alloc->Ideal_length();
2449 // Do not allow make_ideal_length to allocate a CastII node.
2450 Node* len = alloc->make_ideal_length(tary, phase, false);
2451 if (allocated_length == len) {
2452 // Return allocated_length only if it would not be improved by a CastII.
2453 return allocated_length;
2454 }
2455 }
2456 }
2457
2458 return this;
2459
2460 }
2461
2462 //=============================================================================
2463 //---------------------------StoreNode::make-----------------------------------
2464 // Polymorphic factory method:
2465 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2466 assert((mo == unordered || mo == release), "unexpected");
2467 Compile* C = gvn.C;
2468 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2469 ctl != NULL, "raw memory operations should have control edge");
2470
2471 switch (bt) {
2472 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2473 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2474 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2475 case T_CHAR:
2476 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2477 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2478 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2479 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2480 case T_METADATA:
2481 case T_ADDRESS:
2482 case T_OBJECT:
2483 #ifdef _LP64
2484 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2485 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2486 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2487 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2488 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2489 adr->bottom_type()->isa_rawptr())) {
2490 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2491 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2492 }
2493 #endif
2494 {
2495 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2496 }
2497 default:
2498 ShouldNotReachHere();
2499 return (StoreNode*)NULL;
2500 }
2501 }
2502
2503 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2504 bool require_atomic = true;
2505 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2506 }
2507
2508 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2509 bool require_atomic = true;
2510 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2511 }
2512
2513
2514 //--------------------------bottom_type----------------------------------------
2515 const Type *StoreNode::bottom_type() const {
2516 return Type::MEMORY;
2517 }
2518
2519 //------------------------------hash-------------------------------------------
2520 uint StoreNode::hash() const {
2521 // unroll addition of interesting fields
2522 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2523
2524 // Since they are not commoned, do not hash them:
2525 return NO_HASH;
2526 }
2527
2528 //------------------------------Ideal------------------------------------------
2529 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2530 // When a store immediately follows a relevant allocation/initialization,
2531 // try to capture it into the initialization, or hoist it above.
2532 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2533 Node* p = MemNode::Ideal_common(phase, can_reshape);
2534 if (p) return (p == NodeSentinel) ? NULL : p;
2535
2536 Node* mem = in(MemNode::Memory);
2537 Node* address = in(MemNode::Address);
2538 // Back-to-back stores to same address? Fold em up. Generally
2539 // unsafe if I have intervening uses... Also disallowed for StoreCM
2540 // since they must follow each StoreP operation. Redundant StoreCMs
2541 // are eliminated just before matching in final_graph_reshape.
2542 {
2543 Node* st = mem;
2544 // If Store 'st' has more than one use, we cannot fold 'st' away.
2545 // For example, 'st' might be the final state at a conditional
2546 // return. Or, 'st' might be used by some node which is live at
2547 // the same time 'st' is live, which might be unschedulable. So,
2548 // require exactly ONE user until such time as we clone 'mem' for
2549 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2550 // true).
2551 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2552 // Looking at a dead closed cycle of memory?
2553 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2554 assert(Opcode() == st->Opcode() ||
2555 st->Opcode() == Op_StoreVector ||
2556 Opcode() == Op_StoreVector ||
2557 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2558 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2559 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2560 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2561 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2562
2563 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2564 st->as_Store()->memory_size() <= this->memory_size()) {
2565 Node* use = st->raw_out(0);
2566 phase->igvn_rehash_node_delayed(use);
2567 if (can_reshape) {
2568 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2569 } else {
2570 // It's OK to do this in the parser, since DU info is always accurate,
2571 // and the parser always refers to nodes via SafePointNode maps.
2572 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2573 }
2574 return this;
2575 }
2576 st = st->in(MemNode::Memory);
2577 }
2578 }
2579
2580
2581 // Capture an unaliased, unconditional, simple store into an initializer.
2582 // Or, if it is independent of the allocation, hoist it above the allocation.
2583 if (ReduceFieldZeroing && /*can_reshape &&*/
2584 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2585 InitializeNode* init = mem->in(0)->as_Initialize();
2586 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2587 if (offset > 0) {
2588 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2589 // If the InitializeNode captured me, it made a raw copy of me,
2590 // and I need to disappear.
2591 if (moved != NULL) {
2592 // %%% hack to ensure that Ideal returns a new node:
2593 mem = MergeMemNode::make(mem);
2594 return mem; // fold me away
2595 }
2596 }
2597 }
2598
2599 return NULL; // No further progress
2600 }
2601
2602 //------------------------------Value-----------------------------------------
2603 const Type* StoreNode::Value(PhaseGVN* phase) const {
2604 // Either input is TOP ==> the result is TOP
2605 const Type *t1 = phase->type( in(MemNode::Memory) );
2606 if( t1 == Type::TOP ) return Type::TOP;
2607 const Type *t2 = phase->type( in(MemNode::Address) );
2608 if( t2 == Type::TOP ) return Type::TOP;
2609 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2610 if( t3 == Type::TOP ) return Type::TOP;
2611 return Type::MEMORY;
2612 }
2613
2614 //------------------------------Identity---------------------------------------
2615 // Remove redundant stores:
2616 // Store(m, p, Load(m, p)) changes to m.
2617 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2618 Node* StoreNode::Identity(PhaseGVN* phase) {
2619 Node* mem = in(MemNode::Memory);
2620 Node* adr = in(MemNode::Address);
2621 Node* val = in(MemNode::ValueIn);
2622
2623 Node* result = this;
2624
2625 // Load then Store? Then the Store is useless
2626 if (val->is_Load() &&
2627 val->in(MemNode::Address)->eqv_uncast(adr) &&
2628 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2629 val->as_Load()->store_Opcode() == Opcode()) {
2630 result = mem;
2631 }
2632
2633 // Two stores in a row of the same value?
2634 if (result == this &&
2635 mem->is_Store() &&
2636 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2637 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2638 mem->Opcode() == Opcode()) {
2639 result = mem;
2640 }
2641
2642 // Store of zero anywhere into a freshly-allocated object?
2643 // Then the store is useless.
2644 // (It must already have been captured by the InitializeNode.)
2645 if (result == this &&
2646 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2647 // a newly allocated object is already all-zeroes everywhere
2648 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2649 result = mem;
2650 }
2651
2652 if (result == this) {
2653 // the store may also apply to zero-bits in an earlier object
2654 Node* prev_mem = find_previous_store(phase);
2655 // Steps (a), (b): Walk past independent stores to find an exact match.
2656 if (prev_mem != NULL) {
2657 Node* prev_val = can_see_stored_value(prev_mem, phase);
2658 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2659 // prev_val and val might differ by a cast; it would be good
2660 // to keep the more informative of the two.
2661 result = mem;
2662 }
2663 }
2664 }
2665 }
2666
2667 if (result != this && phase->is_IterGVN() != NULL) {
2668 MemBarNode* trailing = trailing_membar();
2669 if (trailing != NULL) {
2670 #ifdef ASSERT
2671 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2672 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2673 #endif
2674 PhaseIterGVN* igvn = phase->is_IterGVN();
2675 trailing->remove(igvn);
2676 }
2677 }
2678
2679 return result;
2680 }
2681
2682 //------------------------------match_edge-------------------------------------
2683 // Do we Match on this edge index or not? Match only memory & value
2684 uint StoreNode::match_edge(uint idx) const {
2685 return idx == MemNode::Address || idx == MemNode::ValueIn;
2686 }
2687
2688 //------------------------------cmp--------------------------------------------
2689 // Do not common stores up together. They generally have to be split
2690 // back up anyways, so do not bother.
2691 uint StoreNode::cmp( const Node &n ) const {
2692 return (&n == this); // Always fail except on self
2693 }
2694
2695 //------------------------------Ideal_masked_input-----------------------------
2696 // Check for a useless mask before a partial-word store
2697 // (StoreB ... (AndI valIn conIa) )
2698 // If (conIa & mask == mask) this simplifies to
2699 // (StoreB ... (valIn) )
2700 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2701 Node *val = in(MemNode::ValueIn);
2702 if( val->Opcode() == Op_AndI ) {
2703 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2704 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2705 set_req(MemNode::ValueIn, val->in(1));
2706 return this;
2707 }
2708 }
2709 return NULL;
2710 }
2711
2712
2713 //------------------------------Ideal_sign_extended_input----------------------
2714 // Check for useless sign-extension before a partial-word store
2715 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2716 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2717 // (StoreB ... (valIn) )
2718 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2719 Node *val = in(MemNode::ValueIn);
2720 if( val->Opcode() == Op_RShiftI ) {
2721 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2722 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2723 Node *shl = val->in(1);
2724 if( shl->Opcode() == Op_LShiftI ) {
2725 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2726 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2727 set_req(MemNode::ValueIn, shl->in(1));
2728 return this;
2729 }
2730 }
2731 }
2732 }
2733 return NULL;
2734 }
2735
2736 //------------------------------value_never_loaded-----------------------------------
2737 // Determine whether there are any possible loads of the value stored.
2738 // For simplicity, we actually check if there are any loads from the
2739 // address stored to, not just for loads of the value stored by this node.
2740 //
2741 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2742 Node *adr = in(Address);
2743 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2744 if (adr_oop == NULL)
2745 return false;
2746 if (!adr_oop->is_known_instance_field())
2747 return false; // if not a distinct instance, there may be aliases of the address
2748 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2749 Node *use = adr->fast_out(i);
2750 if (use->is_Load() || use->is_LoadStore()) {
2751 return false;
2752 }
2753 }
2754 return true;
2755 }
2756
2757 MemBarNode* StoreNode::trailing_membar() const {
2758 if (is_release()) {
2759 MemBarNode* trailing_mb = NULL;
2760 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2761 Node* u = fast_out(i);
2762 if (u->is_MemBar()) {
2763 if (u->as_MemBar()->trailing_store()) {
2764 assert(u->Opcode() == Op_MemBarVolatile, "");
2765 assert(trailing_mb == NULL, "only one");
2766 trailing_mb = u->as_MemBar();
2767 #ifdef ASSERT
2768 Node* leading = u->as_MemBar()->leading_membar();
2769 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2770 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2771 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2772 #endif
2773 } else {
2774 assert(u->as_MemBar()->standalone(), "");
2775 }
2776 }
2777 }
2778 return trailing_mb;
2779 }
2780 return NULL;
2781 }
2782
2783
2784 //=============================================================================
2785 //------------------------------Ideal------------------------------------------
2786 // If the store is from an AND mask that leaves the low bits untouched, then
2787 // we can skip the AND operation. If the store is from a sign-extension
2788 // (a left shift, then right shift) we can skip both.
2789 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2790 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2791 if( progress != NULL ) return progress;
2792
2793 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2794 if( progress != NULL ) return progress;
2795
2796 // Finally check the default case
2797 return StoreNode::Ideal(phase, can_reshape);
2798 }
2799
2800 //=============================================================================
2801 //------------------------------Ideal------------------------------------------
2802 // If the store is from an AND mask that leaves the low bits untouched, then
2803 // we can skip the AND operation
2804 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2805 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2806 if( progress != NULL ) return progress;
2807
2808 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2809 if( progress != NULL ) return progress;
2810
2811 // Finally check the default case
2812 return StoreNode::Ideal(phase, can_reshape);
2813 }
2814
2815 //=============================================================================
2816 //------------------------------Identity---------------------------------------
2817 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2818 // No need to card mark when storing a null ptr
2819 Node* my_store = in(MemNode::OopStore);
2820 if (my_store->is_Store()) {
2821 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2822 if( t1 == TypePtr::NULL_PTR ) {
2823 return in(MemNode::Memory);
2824 }
2825 }
2826 return this;
2827 }
2828
2829 //=============================================================================
2830 //------------------------------Ideal---------------------------------------
2831 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2832 Node* progress = StoreNode::Ideal(phase, can_reshape);
2833 if (progress != NULL) return progress;
2834
2835 Node* my_store = in(MemNode::OopStore);
2836 if (my_store->is_MergeMem()) {
2837 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2838 set_req(MemNode::OopStore, mem);
2839 return this;
2840 }
2841
2842 return NULL;
2843 }
2844
2845 //------------------------------Value-----------------------------------------
2846 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2847 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
2848 // If extra input is TOP ==> the result is TOP
2849 const Type* t = phase->type(in(MemNode::OopStore));
2850 if (t == Type::TOP) {
2851 return Type::TOP;
2852 }
2853 return StoreNode::Value(phase);
2854 }
2855
2856
2857 //=============================================================================
2858 //----------------------------------SCMemProjNode------------------------------
2859 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2860 {
2861 if (in(0) == NULL || phase->type(in(0)) == Type::TOP) {
2862 return Type::TOP;
2863 }
2864 return bottom_type();
2865 }
2866
2867 //=============================================================================
2868 //----------------------------------LoadStoreNode------------------------------
2869 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2870 : Node(required),
2871 _type(rt),
2872 _adr_type(at)
2873 {
2874 init_req(MemNode::Control, c );
2875 init_req(MemNode::Memory , mem);
2876 init_req(MemNode::Address, adr);
2877 init_req(MemNode::ValueIn, val);
2878 init_class_id(Class_LoadStore);
2879 }
2880
2881 //------------------------------Value-----------------------------------------
2882 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
2883 // Either input is TOP ==> the result is TOP
2884 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
2885 return Type::TOP;
2886 }
2887 const Type* t = phase->type(in(MemNode::Memory));
2888 if (t == Type::TOP) {
2889 return Type::TOP;
2890 }
2891 t = phase->type(in(MemNode::Address));
2892 if (t == Type::TOP) {
2893 return Type::TOP;
2894 }
2895 t = phase->type(in(MemNode::ValueIn));
2896 if (t == Type::TOP) {
2897 return Type::TOP;
2898 }
2899 return bottom_type();
2900 }
2901
2902 uint LoadStoreNode::ideal_reg() const {
2903 return _type->ideal_reg();
2904 }
2905
2906 bool LoadStoreNode::result_not_used() const {
2907 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2908 Node *x = fast_out(i);
2909 if (x->Opcode() == Op_SCMemProj) continue;
2910 return false;
2911 }
2912 return true;
2913 }
2914
2915 MemBarNode* LoadStoreNode::trailing_membar() const {
2916 MemBarNode* trailing = NULL;
2917 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2918 Node* u = fast_out(i);
2919 if (u->is_MemBar()) {
2920 if (u->as_MemBar()->trailing_load_store()) {
2921 assert(u->Opcode() == Op_MemBarAcquire, "");
2922 assert(trailing == NULL, "only one");
2923 trailing = u->as_MemBar();
2924 #ifdef ASSERT
2925 Node* leading = trailing->leading_membar();
2926 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2927 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
2928 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
2929 #endif
2930 } else {
2931 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
2932 }
2933 }
2934 }
2935
2936 return trailing;
2937 }
2938
2939 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2940
2941 //=============================================================================
2942 //----------------------------------LoadStoreConditionalNode--------------------
2943 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2944 init_req(ExpectedIn, ex );
2945 }
2946
2947 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
2948 // Either input is TOP ==> the result is TOP
2949 const Type* t = phase->type(in(ExpectedIn));
2950 if (t == Type::TOP) {
2951 return Type::TOP;
2952 }
2953 return LoadStoreNode::Value(phase);
2954 }
2955
2956 //=============================================================================
2957 //-------------------------------adr_type--------------------------------------
2958 const TypePtr* ClearArrayNode::adr_type() const {
2959 Node *adr = in(3);
2960 if (adr == NULL) return NULL; // node is dead
2961 return MemNode::calculate_adr_type(adr->bottom_type());
2962 }
2963
2964 //------------------------------match_edge-------------------------------------
2965 // Do we Match on this edge index or not? Do not match memory
2966 uint ClearArrayNode::match_edge(uint idx) const {
2967 return idx > 1;
2968 }
2969
2970 //------------------------------Identity---------------------------------------
2971 // Clearing a zero length array does nothing
2972 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2973 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2974 }
2975
2976 //------------------------------Idealize---------------------------------------
2977 // Clearing a short array is faster with stores
2978 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2979 // Already know this is a large node, do not try to ideal it
2980 if (!IdealizeClearArrayNode || _is_large) return NULL;
2981
2982 const int unit = BytesPerLong;
2983 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2984 if (!t) return NULL;
2985 if (!t->is_con()) return NULL;
2986 intptr_t raw_count = t->get_con();
2987 intptr_t size = raw_count;
2988 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2989 // Clearing nothing uses the Identity call.
2990 // Negative clears are possible on dead ClearArrays
2991 // (see jck test stmt114.stmt11402.val).
2992 if (size <= 0 || size % unit != 0) return NULL;
2993 intptr_t count = size / unit;
2994 // Length too long; communicate this to matchers and assemblers.
2995 // Assemblers are responsible to produce fast hardware clears for it.
2996 if (size > InitArrayShortSize) {
2997 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2998 }
2999 Node *mem = in(1);
3000 if( phase->type(mem)==Type::TOP ) return NULL;
3001 Node *adr = in(3);
3002 const Type* at = phase->type(adr);
3003 if( at==Type::TOP ) return NULL;
3004 const TypePtr* atp = at->isa_ptr();
3005 // adjust atp to be the correct array element address type
3006 if (atp == NULL) atp = TypePtr::BOTTOM;
3007 else atp = atp->add_offset(Type::OffsetBot);
3008 // Get base for derived pointer purposes
3009 if( adr->Opcode() != Op_AddP ) Unimplemented();
3010 Node *base = adr->in(1);
3011
3012 Node *zero = phase->makecon(TypeLong::ZERO);
3013 Node *off = phase->MakeConX(BytesPerLong);
3014 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3015 count--;
3016 while( count-- ) {
3017 mem = phase->transform(mem);
3018 adr = phase->transform(new AddPNode(base,adr,off));
3019 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3020 }
3021 return mem;
3022 }
3023
3024 //----------------------------step_through----------------------------------
3025 // Return allocation input memory edge if it is different instance
3026 // or itself if it is the one we are looking for.
3027 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3028 Node* n = *np;
3029 assert(n->is_ClearArray(), "sanity");
3030 intptr_t offset;
3031 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3032 // This method is called only before Allocate nodes are expanded
3033 // during macro nodes expansion. Before that ClearArray nodes are
3034 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3035 // Allocate nodes are expanded) which follows allocations.
3036 assert(alloc != NULL, "should have allocation");
3037 if (alloc->_idx == instance_id) {
3038 // Can not bypass initialization of the instance we are looking for.
3039 return false;
3040 }
3041 // Otherwise skip it.
3042 InitializeNode* init = alloc->initialization();
3043 if (init != NULL)
3044 *np = init->in(TypeFunc::Memory);
3045 else
3046 *np = alloc->in(TypeFunc::Memory);
3047 return true;
3048 }
3049
3050 //----------------------------clear_memory-------------------------------------
3051 // Generate code to initialize object storage to zero.
3052 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3053 intptr_t start_offset,
3054 Node* end_offset,
3055 PhaseGVN* phase) {
3056 intptr_t offset = start_offset;
3057
3058 int unit = BytesPerLong;
3059 if ((offset % unit) != 0) {
3060 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3061 adr = phase->transform(adr);
3062 const TypePtr* atp = TypeRawPtr::BOTTOM;
3063 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3064 mem = phase->transform(mem);
3065 offset += BytesPerInt;
3066 }
3067 assert((offset % unit) == 0, "");
3068
3069 // Initialize the remaining stuff, if any, with a ClearArray.
3070 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
3071 }
3072
3073 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3074 Node* start_offset,
3075 Node* end_offset,
3076 PhaseGVN* phase) {
3077 if (start_offset == end_offset) {
3078 // nothing to do
3079 return mem;
3080 }
3081
3082 int unit = BytesPerLong;
3083 Node* zbase = start_offset;
3084 Node* zend = end_offset;
3085
3086 // Scale to the unit required by the CPU:
3087 if (!Matcher::init_array_count_is_in_bytes) {
3088 Node* shift = phase->intcon(exact_log2(unit));
3089 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3090 zend = phase->transform(new URShiftXNode(zend, shift) );
3091 }
3092
3093 // Bulk clear double-words
3094 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3095 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3096 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
3097 return phase->transform(mem);
3098 }
3099
3100 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3101 intptr_t start_offset,
3102 intptr_t end_offset,
3103 PhaseGVN* phase) {
3104 if (start_offset == end_offset) {
3105 // nothing to do
3106 return mem;
3107 }
3108
3109 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3110 intptr_t done_offset = end_offset;
3111 if ((done_offset % BytesPerLong) != 0) {
3112 done_offset -= BytesPerInt;
3113 }
3114 if (done_offset > start_offset) {
3115 mem = clear_memory(ctl, mem, dest,
3116 start_offset, phase->MakeConX(done_offset), phase);
3117 }
3118 if (done_offset < end_offset) { // emit the final 32-bit store
3119 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3120 adr = phase->transform(adr);
3121 const TypePtr* atp = TypeRawPtr::BOTTOM;
3122 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3123 mem = phase->transform(mem);
3124 done_offset += BytesPerInt;
3125 }
3126 assert(done_offset == end_offset, "");
3127 return mem;
3128 }
3129
3130 //=============================================================================
3131 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3132 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3133 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3134 #ifdef ASSERT
3135 , _pair_idx(0)
3136 #endif
3137 {
3138 init_class_id(Class_MemBar);
3139 Node* top = C->top();
3140 init_req(TypeFunc::I_O,top);
3141 init_req(TypeFunc::FramePtr,top);
3142 init_req(TypeFunc::ReturnAdr,top);
3143 if (precedent != NULL)
3144 init_req(TypeFunc::Parms, precedent);
3145 }
3146
3147 //------------------------------cmp--------------------------------------------
3148 uint MemBarNode::hash() const { return NO_HASH; }
3149 uint MemBarNode::cmp( const Node &n ) const {
3150 return (&n == this); // Always fail except on self
3151 }
3152
3153 //------------------------------make-------------------------------------------
3154 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3155 switch (opcode) {
3156 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3157 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3158 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3159 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3160 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3161 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3162 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3163 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3164 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3165 case Op_Initialize: return new InitializeNode(C, atp, pn);
3166 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3167 default: ShouldNotReachHere(); return NULL;
3168 }
3169 }
3170
3171 void MemBarNode::remove(PhaseIterGVN *igvn) {
3172 if (outcnt() != 2) {
3173 return;
3174 }
3175 if (trailing_store() || trailing_load_store()) {
3176 MemBarNode* leading = leading_membar();
3177 if (leading != NULL) {
3178 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3179 leading->remove(igvn);
3180 }
3181 }
3182 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3183 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3184 }
3185
3186 //------------------------------Ideal------------------------------------------
3187 // Return a node which is more "ideal" than the current node. Strip out
3188 // control copies
3189 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3190 if (remove_dead_region(phase, can_reshape)) return this;
3191 // Don't bother trying to transform a dead node
3192 if (in(0) && in(0)->is_top()) {
3193 return NULL;
3194 }
3195
3196 #if INCLUDE_ZGC
3197 if (UseZGC) {
3198 if (req() == (Precedent+1) && in(MemBarNode::Precedent)->in(0) != NULL && in(MemBarNode::Precedent)->in(0)->is_LoadBarrier()) {
3199 Node* load_node = in(MemBarNode::Precedent)->in(0)->in(LoadBarrierNode::Oop);
3200 set_req(MemBarNode::Precedent, load_node);
3201 return this;
3202 }
3203 }
3204 #endif
3205
3206 bool progress = false;
3207 // Eliminate volatile MemBars for scalar replaced objects.
3208 if (can_reshape && req() == (Precedent+1)) {
3209 bool eliminate = false;
3210 int opc = Opcode();
3211 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3212 // Volatile field loads and stores.
3213 Node* my_mem = in(MemBarNode::Precedent);
3214 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3215 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3216 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3217 // replace this Precedent (decodeN) with the Load instead.
3218 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3219 Node* load_node = my_mem->in(1);
3220 set_req(MemBarNode::Precedent, load_node);
3221 phase->is_IterGVN()->_worklist.push(my_mem);
3222 my_mem = load_node;
3223 } else {
3224 assert(my_mem->unique_out() == this, "sanity");
3225 del_req(Precedent);
3226 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3227 my_mem = NULL;
3228 }
3229 progress = true;
3230 }
3231 if (my_mem != NULL && my_mem->is_Mem()) {
3232 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3233 // Check for scalar replaced object reference.
3234 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3235 t_oop->offset() != Type::OffsetBot &&
3236 t_oop->offset() != Type::OffsetTop) {
3237 eliminate = true;
3238 }
3239 }
3240 } else if (opc == Op_MemBarRelease) {
3241 // Final field stores.
3242 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3243 if ((alloc != NULL) && alloc->is_Allocate() &&
3244 alloc->as_Allocate()->does_not_escape_thread()) {
3245 // The allocated object does not escape.
3246 eliminate = true;
3247 }
3248 }
3249 if (eliminate) {
3250 // Replace MemBar projections by its inputs.
3251 PhaseIterGVN* igvn = phase->is_IterGVN();
3252 remove(igvn);
3253 // Must return either the original node (now dead) or a new node
3254 // (Do not return a top here, since that would break the uniqueness of top.)
3255 return new ConINode(TypeInt::ZERO);
3256 }
3257 }
3258 return progress ? this : NULL;
3259 }
3260
3261 //------------------------------Value------------------------------------------
3262 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3263 if( !in(0) ) return Type::TOP;
3264 if( phase->type(in(0)) == Type::TOP )
3265 return Type::TOP;
3266 return TypeTuple::MEMBAR;
3267 }
3268
3269 //------------------------------match------------------------------------------
3270 // Construct projections for memory.
3271 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3272 switch (proj->_con) {
3273 case TypeFunc::Control:
3274 case TypeFunc::Memory:
3275 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3276 }
3277 ShouldNotReachHere();
3278 return NULL;
3279 }
3280
3281 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3282 trailing->_kind = TrailingStore;
3283 leading->_kind = LeadingStore;
3284 #ifdef ASSERT
3285 trailing->_pair_idx = leading->_idx;
3286 leading->_pair_idx = leading->_idx;
3287 #endif
3288 }
3289
3290 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3291 trailing->_kind = TrailingLoadStore;
3292 leading->_kind = LeadingLoadStore;
3293 #ifdef ASSERT
3294 trailing->_pair_idx = leading->_idx;
3295 leading->_pair_idx = leading->_idx;
3296 #endif
3297 }
3298
3299 MemBarNode* MemBarNode::trailing_membar() const {
3300 ResourceMark rm;
3301 Node* trailing = (Node*)this;
3302 VectorSet seen(Thread::current()->resource_area());
3303 Node_Stack multis(0);
3304 do {
3305 Node* c = trailing;
3306 uint i = 0;
3307 do {
3308 trailing = NULL;
3309 for (; i < c->outcnt(); i++) {
3310 Node* next = c->raw_out(i);
3311 if (next != c && next->is_CFG()) {
3312 if (c->is_MultiBranch()) {
3313 if (multis.node() == c) {
3314 multis.set_index(i+1);
3315 } else {
3316 multis.push(c, i+1);
3317 }
3318 }
3319 trailing = next;
3320 break;
3321 }
3322 }
3323 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3324 break;
3325 }
3326 while (multis.size() > 0) {
3327 c = multis.node();
3328 i = multis.index();
3329 if (i < c->req()) {
3330 break;
3331 }
3332 multis.pop();
3333 }
3334 } while (multis.size() > 0);
3335 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3336
3337 MemBarNode* mb = trailing->as_MemBar();
3338 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3339 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3340 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3341 return mb;
3342 }
3343
3344 MemBarNode* MemBarNode::leading_membar() const {
3345 ResourceMark rm;
3346 VectorSet seen(Thread::current()->resource_area());
3347 Node_Stack regions(0);
3348 Node* leading = in(0);
3349 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3350 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3351 leading = NULL;
3352 while (regions.size() > 0 && leading == NULL) {
3353 Node* r = regions.node();
3354 uint i = regions.index();
3355 if (i < r->req()) {
3356 leading = r->in(i);
3357 regions.set_index(i+1);
3358 } else {
3359 regions.pop();
3360 }
3361 }
3362 if (leading == NULL) {
3363 assert(regions.size() == 0, "all paths should have been tried");
3364 return NULL;
3365 }
3366 }
3367 if (leading->is_Region()) {
3368 regions.push(leading, 2);
3369 leading = leading->in(1);
3370 } else {
3371 leading = leading->in(0);
3372 }
3373 }
3374 #ifdef ASSERT
3375 Unique_Node_List wq;
3376 wq.push((Node*)this);
3377 uint found = 0;
3378 for (uint i = 0; i < wq.size(); i++) {
3379 Node* n = wq.at(i);
3380 if (n->is_Region()) {
3381 for (uint j = 1; j < n->req(); j++) {
3382 Node* in = n->in(j);
3383 if (in != NULL && !in->is_top()) {
3384 wq.push(in);
3385 }
3386 }
3387 } else {
3388 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3389 assert(n == leading, "consistency check failed");
3390 found++;
3391 } else {
3392 Node* in = n->in(0);
3393 if (in != NULL && !in->is_top()) {
3394 wq.push(in);
3395 }
3396 }
3397 }
3398 }
3399 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3400 #endif
3401 if (leading == NULL) {
3402 return NULL;
3403 }
3404 MemBarNode* mb = leading->as_MemBar();
3405 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3406 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3407 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3408 return mb;
3409 }
3410
3411 //===========================InitializeNode====================================
3412 // SUMMARY:
3413 // This node acts as a memory barrier on raw memory, after some raw stores.
3414 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3415 // The Initialize can 'capture' suitably constrained stores as raw inits.
3416 // It can coalesce related raw stores into larger units (called 'tiles').
3417 // It can avoid zeroing new storage for memory units which have raw inits.
3418 // At macro-expansion, it is marked 'complete', and does not optimize further.
3419 //
3420 // EXAMPLE:
3421 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3422 // ctl = incoming control; mem* = incoming memory
3423 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3424 // First allocate uninitialized memory and fill in the header:
3425 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3426 // ctl := alloc.Control; mem* := alloc.Memory*
3427 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3428 // Then initialize to zero the non-header parts of the raw memory block:
3429 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3430 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3431 // After the initialize node executes, the object is ready for service:
3432 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3433 // Suppose its body is immediately initialized as {1,2}:
3434 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3435 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3436 // mem.SLICE(#short[*]) := store2
3437 //
3438 // DETAILS:
3439 // An InitializeNode collects and isolates object initialization after
3440 // an AllocateNode and before the next possible safepoint. As a
3441 // memory barrier (MemBarNode), it keeps critical stores from drifting
3442 // down past any safepoint or any publication of the allocation.
3443 // Before this barrier, a newly-allocated object may have uninitialized bits.
3444 // After this barrier, it may be treated as a real oop, and GC is allowed.
3445 //
3446 // The semantics of the InitializeNode include an implicit zeroing of
3447 // the new object from object header to the end of the object.
3448 // (The object header and end are determined by the AllocateNode.)
3449 //
3450 // Certain stores may be added as direct inputs to the InitializeNode.
3451 // These stores must update raw memory, and they must be to addresses
3452 // derived from the raw address produced by AllocateNode, and with
3453 // a constant offset. They must be ordered by increasing offset.
3454 // The first one is at in(RawStores), the last at in(req()-1).
3455 // Unlike most memory operations, they are not linked in a chain,
3456 // but are displayed in parallel as users of the rawmem output of
3457 // the allocation.
3458 //
3459 // (See comments in InitializeNode::capture_store, which continue
3460 // the example given above.)
3461 //
3462 // When the associated Allocate is macro-expanded, the InitializeNode
3463 // may be rewritten to optimize collected stores. A ClearArrayNode
3464 // may also be created at that point to represent any required zeroing.
3465 // The InitializeNode is then marked 'complete', prohibiting further
3466 // capturing of nearby memory operations.
3467 //
3468 // During macro-expansion, all captured initializations which store
3469 // constant values of 32 bits or smaller are coalesced (if advantageous)
3470 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3471 // initialized in fewer memory operations. Memory words which are
3472 // covered by neither tiles nor non-constant stores are pre-zeroed
3473 // by explicit stores of zero. (The code shape happens to do all
3474 // zeroing first, then all other stores, with both sequences occurring
3475 // in order of ascending offsets.)
3476 //
3477 // Alternatively, code may be inserted between an AllocateNode and its
3478 // InitializeNode, to perform arbitrary initialization of the new object.
3479 // E.g., the object copying intrinsics insert complex data transfers here.
3480 // The initialization must then be marked as 'complete' disable the
3481 // built-in zeroing semantics and the collection of initializing stores.
3482 //
3483 // While an InitializeNode is incomplete, reads from the memory state
3484 // produced by it are optimizable if they match the control edge and
3485 // new oop address associated with the allocation/initialization.
3486 // They return a stored value (if the offset matches) or else zero.
3487 // A write to the memory state, if it matches control and address,
3488 // and if it is to a constant offset, may be 'captured' by the
3489 // InitializeNode. It is cloned as a raw memory operation and rewired
3490 // inside the initialization, to the raw oop produced by the allocation.
3491 // Operations on addresses which are provably distinct (e.g., to
3492 // other AllocateNodes) are allowed to bypass the initialization.
3493 //
3494 // The effect of all this is to consolidate object initialization
3495 // (both arrays and non-arrays, both piecewise and bulk) into a
3496 // single location, where it can be optimized as a unit.
3497 //
3498 // Only stores with an offset less than TrackedInitializationLimit words
3499 // will be considered for capture by an InitializeNode. This puts a
3500 // reasonable limit on the complexity of optimized initializations.
3501
3502 //---------------------------InitializeNode------------------------------------
3503 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3504 : _is_complete(Incomplete), _does_not_escape(false),
3505 MemBarNode(C, adr_type, rawoop)
3506 {
3507 init_class_id(Class_Initialize);
3508
3509 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3510 assert(in(RawAddress) == rawoop, "proper init");
3511 // Note: allocation() can be NULL, for secondary initialization barriers
3512 }
3513
3514 // Since this node is not matched, it will be processed by the
3515 // register allocator. Declare that there are no constraints
3516 // on the allocation of the RawAddress edge.
3517 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3518 // This edge should be set to top, by the set_complete. But be conservative.
3519 if (idx == InitializeNode::RawAddress)
3520 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3521 return RegMask::Empty;
3522 }
3523
3524 Node* InitializeNode::memory(uint alias_idx) {
3525 Node* mem = in(Memory);
3526 if (mem->is_MergeMem()) {
3527 return mem->as_MergeMem()->memory_at(alias_idx);
3528 } else {
3529 // incoming raw memory is not split
3530 return mem;
3531 }
3532 }
3533
3534 bool InitializeNode::is_non_zero() {
3535 if (is_complete()) return false;
3536 remove_extra_zeroes();
3537 return (req() > RawStores);
3538 }
3539
3540 void InitializeNode::set_complete(PhaseGVN* phase) {
3541 assert(!is_complete(), "caller responsibility");
3542 _is_complete = Complete;
3543
3544 // After this node is complete, it contains a bunch of
3545 // raw-memory initializations. There is no need for
3546 // it to have anything to do with non-raw memory effects.
3547 // Therefore, tell all non-raw users to re-optimize themselves,
3548 // after skipping the memory effects of this initialization.
3549 PhaseIterGVN* igvn = phase->is_IterGVN();
3550 if (igvn) igvn->add_users_to_worklist(this);
3551 }
3552
3553 // convenience function
3554 // return false if the init contains any stores already
3555 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3556 InitializeNode* init = initialization();
3557 if (init == NULL || init->is_complete()) return false;
3558 init->remove_extra_zeroes();
3559 // for now, if this allocation has already collected any inits, bail:
3560 if (init->is_non_zero()) return false;
3561 init->set_complete(phase);
3562 return true;
3563 }
3564
3565 void InitializeNode::remove_extra_zeroes() {
3566 if (req() == RawStores) return;
3567 Node* zmem = zero_memory();
3568 uint fill = RawStores;
3569 for (uint i = fill; i < req(); i++) {
3570 Node* n = in(i);
3571 if (n->is_top() || n == zmem) continue; // skip
3572 if (fill < i) set_req(fill, n); // compact
3573 ++fill;
3574 }
3575 // delete any empty spaces created:
3576 while (fill < req()) {
3577 del_req(fill);
3578 }
3579 }
3580
3581 // Helper for remembering which stores go with which offsets.
3582 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3583 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3584 intptr_t offset = -1;
3585 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3586 phase, offset);
3587 if (base == NULL) return -1; // something is dead,
3588 if (offset < 0) return -1; // dead, dead
3589 return offset;
3590 }
3591
3592 // Helper for proving that an initialization expression is
3593 // "simple enough" to be folded into an object initialization.
3594 // Attempts to prove that a store's initial value 'n' can be captured
3595 // within the initialization without creating a vicious cycle, such as:
3596 // { Foo p = new Foo(); p.next = p; }
3597 // True for constants and parameters and small combinations thereof.
3598 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3599 if (n == NULL) return true; // (can this really happen?)
3600 if (n->is_Proj()) n = n->in(0);
3601 if (n == this) return false; // found a cycle
3602 if (n->is_Con()) return true;
3603 if (n->is_Start()) return true; // params, etc., are OK
3604 if (n->is_Root()) return true; // even better
3605
3606 Node* ctl = n->in(0);
3607 if (ctl != NULL && !ctl->is_top()) {
3608 if (ctl->is_Proj()) ctl = ctl->in(0);
3609 if (ctl == this) return false;
3610
3611 // If we already know that the enclosing memory op is pinned right after
3612 // the init, then any control flow that the store has picked up
3613 // must have preceded the init, or else be equal to the init.
3614 // Even after loop optimizations (which might change control edges)
3615 // a store is never pinned *before* the availability of its inputs.
3616 if (!MemNode::all_controls_dominate(n, this))
3617 return false; // failed to prove a good control
3618 }
3619
3620 // Check data edges for possible dependencies on 'this'.
3621 if ((count += 1) > 20) return false; // complexity limit
3622 for (uint i = 1; i < n->req(); i++) {
3623 Node* m = n->in(i);
3624 if (m == NULL || m == n || m->is_top()) continue;
3625 uint first_i = n->find_edge(m);
3626 if (i != first_i) continue; // process duplicate edge just once
3627 if (!detect_init_independence(m, count)) {
3628 return false;
3629 }
3630 }
3631
3632 return true;
3633 }
3634
3635 // Here are all the checks a Store must pass before it can be moved into
3636 // an initialization. Returns zero if a check fails.
3637 // On success, returns the (constant) offset to which the store applies,
3638 // within the initialized memory.
3639 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3640 const int FAIL = 0;
3641 if (st->req() != MemNode::ValueIn + 1)
3642 return FAIL; // an inscrutable StoreNode (card mark?)
3643 Node* ctl = st->in(MemNode::Control);
3644 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3645 return FAIL; // must be unconditional after the initialization
3646 Node* mem = st->in(MemNode::Memory);
3647 if (!(mem->is_Proj() && mem->in(0) == this))
3648 return FAIL; // must not be preceded by other stores
3649 Node* adr = st->in(MemNode::Address);
3650 intptr_t offset;
3651 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3652 if (alloc == NULL)
3653 return FAIL; // inscrutable address
3654 if (alloc != allocation())
3655 return FAIL; // wrong allocation! (store needs to float up)
3656 int size_in_bytes = st->memory_size();
3657 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3658 return FAIL; // mismatched access
3659 }
3660 Node* val = st->in(MemNode::ValueIn);
3661 int complexity_count = 0;
3662 if (!detect_init_independence(val, complexity_count))
3663 return FAIL; // stored value must be 'simple enough'
3664
3665 // The Store can be captured only if nothing after the allocation
3666 // and before the Store is using the memory location that the store
3667 // overwrites.
3668 bool failed = false;
3669 // If is_complete_with_arraycopy() is true the shape of the graph is
3670 // well defined and is safe so no need for extra checks.
3671 if (!is_complete_with_arraycopy()) {
3672 // We are going to look at each use of the memory state following
3673 // the allocation to make sure nothing reads the memory that the
3674 // Store writes.
3675 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3676 int alias_idx = phase->C->get_alias_index(t_adr);
3677 ResourceMark rm;
3678 Unique_Node_List mems;
3679 mems.push(mem);
3680 Node* unique_merge = NULL;
3681 for (uint next = 0; next < mems.size(); ++next) {
3682 Node *m = mems.at(next);
3683 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3684 Node *n = m->fast_out(j);
3685 if (n->outcnt() == 0) {
3686 continue;
3687 }
3688 if (n == st) {
3689 continue;
3690 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3691 // If the control of this use is different from the control
3692 // of the Store which is right after the InitializeNode then
3693 // this node cannot be between the InitializeNode and the
3694 // Store.
3695 continue;
3696 } else if (n->is_MergeMem()) {
3697 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3698 // We can hit a MergeMemNode (that will likely go away
3699 // later) that is a direct use of the memory state
3700 // following the InitializeNode on the same slice as the
3701 // store node that we'd like to capture. We need to check
3702 // the uses of the MergeMemNode.
3703 mems.push(n);
3704 }
3705 } else if (n->is_Mem()) {
3706 Node* other_adr = n->in(MemNode::Address);
3707 if (other_adr == adr) {
3708 failed = true;
3709 break;
3710 } else {
3711 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3712 if (other_t_adr != NULL) {
3713 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3714 if (other_alias_idx == alias_idx) {
3715 // A load from the same memory slice as the store right
3716 // after the InitializeNode. We check the control of the
3717 // object/array that is loaded from. If it's the same as
3718 // the store control then we cannot capture the store.
3719 assert(!n->is_Store(), "2 stores to same slice on same control?");
3720 Node* base = other_adr;
3721 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3722 base = base->in(AddPNode::Base);
3723 if (base != NULL) {
3724 base = base->uncast();
3725 if (base->is_Proj() && base->in(0) == alloc) {
3726 failed = true;
3727 break;
3728 }
3729 }
3730 }
3731 }
3732 }
3733 } else {
3734 failed = true;
3735 break;
3736 }
3737 }
3738 }
3739 }
3740 if (failed) {
3741 if (!can_reshape) {
3742 // We decided we couldn't capture the store during parsing. We
3743 // should try again during the next IGVN once the graph is
3744 // cleaner.
3745 phase->C->record_for_igvn(st);
3746 }
3747 return FAIL;
3748 }
3749
3750 return offset; // success
3751 }
3752
3753 // Find the captured store in(i) which corresponds to the range
3754 // [start..start+size) in the initialized object.
3755 // If there is one, return its index i. If there isn't, return the
3756 // negative of the index where it should be inserted.
3757 // Return 0 if the queried range overlaps an initialization boundary
3758 // or if dead code is encountered.
3759 // If size_in_bytes is zero, do not bother with overlap checks.
3760 int InitializeNode::captured_store_insertion_point(intptr_t start,
3761 int size_in_bytes,
3762 PhaseTransform* phase) {
3763 const int FAIL = 0, MAX_STORE = BytesPerLong;
3764
3765 if (is_complete())
3766 return FAIL; // arraycopy got here first; punt
3767
3768 assert(allocation() != NULL, "must be present");
3769
3770 // no negatives, no header fields:
3771 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3772
3773 // after a certain size, we bail out on tracking all the stores:
3774 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3775 if (start >= ti_limit) return FAIL;
3776
3777 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3778 if (i >= limit) return -(int)i; // not found; here is where to put it
3779
3780 Node* st = in(i);
3781 intptr_t st_off = get_store_offset(st, phase);
3782 if (st_off < 0) {
3783 if (st != zero_memory()) {
3784 return FAIL; // bail out if there is dead garbage
3785 }
3786 } else if (st_off > start) {
3787 // ...we are done, since stores are ordered
3788 if (st_off < start + size_in_bytes) {
3789 return FAIL; // the next store overlaps
3790 }
3791 return -(int)i; // not found; here is where to put it
3792 } else if (st_off < start) {
3793 if (size_in_bytes != 0 &&
3794 start < st_off + MAX_STORE &&
3795 start < st_off + st->as_Store()->memory_size()) {
3796 return FAIL; // the previous store overlaps
3797 }
3798 } else {
3799 if (size_in_bytes != 0 &&
3800 st->as_Store()->memory_size() != size_in_bytes) {
3801 return FAIL; // mismatched store size
3802 }
3803 return i;
3804 }
3805
3806 ++i;
3807 }
3808 }
3809
3810 // Look for a captured store which initializes at the offset 'start'
3811 // with the given size. If there is no such store, and no other
3812 // initialization interferes, then return zero_memory (the memory
3813 // projection of the AllocateNode).
3814 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3815 PhaseTransform* phase) {
3816 assert(stores_are_sane(phase), "");
3817 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3818 if (i == 0) {
3819 return NULL; // something is dead
3820 } else if (i < 0) {
3821 return zero_memory(); // just primordial zero bits here
3822 } else {
3823 Node* st = in(i); // here is the store at this position
3824 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3825 return st;
3826 }
3827 }
3828
3829 // Create, as a raw pointer, an address within my new object at 'offset'.
3830 Node* InitializeNode::make_raw_address(intptr_t offset,
3831 PhaseTransform* phase) {
3832 Node* addr = in(RawAddress);
3833 if (offset != 0) {
3834 Compile* C = phase->C;
3835 addr = phase->transform( new AddPNode(C->top(), addr,
3836 phase->MakeConX(offset)) );
3837 }
3838 return addr;
3839 }
3840
3841 // Clone the given store, converting it into a raw store
3842 // initializing a field or element of my new object.
3843 // Caller is responsible for retiring the original store,
3844 // with subsume_node or the like.
3845 //
3846 // From the example above InitializeNode::InitializeNode,
3847 // here are the old stores to be captured:
3848 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3849 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3850 //
3851 // Here is the changed code; note the extra edges on init:
3852 // alloc = (Allocate ...)
3853 // rawoop = alloc.RawAddress
3854 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3855 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3856 // init = (Initialize alloc.Control alloc.Memory rawoop
3857 // rawstore1 rawstore2)
3858 //
3859 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3860 PhaseTransform* phase, bool can_reshape) {
3861 assert(stores_are_sane(phase), "");
3862
3863 if (start < 0) return NULL;
3864 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3865
3866 Compile* C = phase->C;
3867 int size_in_bytes = st->memory_size();
3868 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3869 if (i == 0) return NULL; // bail out
3870 Node* prev_mem = NULL; // raw memory for the captured store
3871 if (i > 0) {
3872 prev_mem = in(i); // there is a pre-existing store under this one
3873 set_req(i, C->top()); // temporarily disconnect it
3874 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3875 } else {
3876 i = -i; // no pre-existing store
3877 prev_mem = zero_memory(); // a slice of the newly allocated object
3878 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3879 set_req(--i, C->top()); // reuse this edge; it has been folded away
3880 else
3881 ins_req(i, C->top()); // build a new edge
3882 }
3883 Node* new_st = st->clone();
3884 new_st->set_req(MemNode::Control, in(Control));
3885 new_st->set_req(MemNode::Memory, prev_mem);
3886 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3887 new_st = phase->transform(new_st);
3888
3889 // At this point, new_st might have swallowed a pre-existing store
3890 // at the same offset, or perhaps new_st might have disappeared,
3891 // if it redundantly stored the same value (or zero to fresh memory).
3892
3893 // In any case, wire it in:
3894 phase->igvn_rehash_node_delayed(this);
3895 set_req(i, new_st);
3896
3897 // The caller may now kill the old guy.
3898 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3899 assert(check_st == new_st || check_st == NULL, "must be findable");
3900 assert(!is_complete(), "");
3901 return new_st;
3902 }
3903
3904 static bool store_constant(jlong* tiles, int num_tiles,
3905 intptr_t st_off, int st_size,
3906 jlong con) {
3907 if ((st_off & (st_size-1)) != 0)
3908 return false; // strange store offset (assume size==2**N)
3909 address addr = (address)tiles + st_off;
3910 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3911 switch (st_size) {
3912 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3913 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3914 case sizeof(jint): *(jint*) addr = (jint) con; break;
3915 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3916 default: return false; // strange store size (detect size!=2**N here)
3917 }
3918 return true; // return success to caller
3919 }
3920
3921 // Coalesce subword constants into int constants and possibly
3922 // into long constants. The goal, if the CPU permits,
3923 // is to initialize the object with a small number of 64-bit tiles.
3924 // Also, convert floating-point constants to bit patterns.
3925 // Non-constants are not relevant to this pass.
3926 //
3927 // In terms of the running example on InitializeNode::InitializeNode
3928 // and InitializeNode::capture_store, here is the transformation
3929 // of rawstore1 and rawstore2 into rawstore12:
3930 // alloc = (Allocate ...)
3931 // rawoop = alloc.RawAddress
3932 // tile12 = 0x00010002
3933 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3934 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3935 //
3936 void
3937 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3938 Node* size_in_bytes,
3939 PhaseGVN* phase) {
3940 Compile* C = phase->C;
3941
3942 assert(stores_are_sane(phase), "");
3943 // Note: After this pass, they are not completely sane,
3944 // since there may be some overlaps.
3945
3946 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3947
3948 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3949 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3950 size_limit = MIN2(size_limit, ti_limit);
3951 size_limit = align_up(size_limit, BytesPerLong);
3952 int num_tiles = size_limit / BytesPerLong;
3953
3954 // allocate space for the tile map:
3955 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3956 jlong tiles_buf[small_len];
3957 Node* nodes_buf[small_len];
3958 jlong inits_buf[small_len];
3959 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3960 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3961 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3962 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3963 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3964 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3965 // tiles: exact bitwise model of all primitive constants
3966 // nodes: last constant-storing node subsumed into the tiles model
3967 // inits: which bytes (in each tile) are touched by any initializations
3968
3969 //// Pass A: Fill in the tile model with any relevant stores.
3970
3971 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3972 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3973 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3974 Node* zmem = zero_memory(); // initially zero memory state
3975 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3976 Node* st = in(i);
3977 intptr_t st_off = get_store_offset(st, phase);
3978
3979 // Figure out the store's offset and constant value:
3980 if (st_off < header_size) continue; //skip (ignore header)
3981 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3982 int st_size = st->as_Store()->memory_size();
3983 if (st_off + st_size > size_limit) break;
3984
3985 // Record which bytes are touched, whether by constant or not.
3986 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3987 continue; // skip (strange store size)
3988
3989 const Type* val = phase->type(st->in(MemNode::ValueIn));
3990 if (!val->singleton()) continue; //skip (non-con store)
3991 BasicType type = val->basic_type();
3992
3993 jlong con = 0;
3994 switch (type) {
3995 case T_INT: con = val->is_int()->get_con(); break;
3996 case T_LONG: con = val->is_long()->get_con(); break;
3997 case T_FLOAT: con = jint_cast(val->getf()); break;
3998 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3999 default: continue; //skip (odd store type)
4000 }
4001
4002 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4003 st->Opcode() == Op_StoreL) {
4004 continue; // This StoreL is already optimal.
4005 }
4006
4007 // Store down the constant.
4008 store_constant(tiles, num_tiles, st_off, st_size, con);
4009
4010 intptr_t j = st_off >> LogBytesPerLong;
4011
4012 if (type == T_INT && st_size == BytesPerInt
4013 && (st_off & BytesPerInt) == BytesPerInt) {
4014 jlong lcon = tiles[j];
4015 if (!Matcher::isSimpleConstant64(lcon) &&
4016 st->Opcode() == Op_StoreI) {
4017 // This StoreI is already optimal by itself.
4018 jint* intcon = (jint*) &tiles[j];
4019 intcon[1] = 0; // undo the store_constant()
4020
4021 // If the previous store is also optimal by itself, back up and
4022 // undo the action of the previous loop iteration... if we can.
4023 // But if we can't, just let the previous half take care of itself.
4024 st = nodes[j];
4025 st_off -= BytesPerInt;
4026 con = intcon[0];
4027 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4028 assert(st_off >= header_size, "still ignoring header");
4029 assert(get_store_offset(st, phase) == st_off, "must be");
4030 assert(in(i-1) == zmem, "must be");
4031 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4032 assert(con == tcon->is_int()->get_con(), "must be");
4033 // Undo the effects of the previous loop trip, which swallowed st:
4034 intcon[0] = 0; // undo store_constant()
4035 set_req(i-1, st); // undo set_req(i, zmem)
4036 nodes[j] = NULL; // undo nodes[j] = st
4037 --old_subword; // undo ++old_subword
4038 }
4039 continue; // This StoreI is already optimal.
4040 }
4041 }
4042
4043 // This store is not needed.
4044 set_req(i, zmem);
4045 nodes[j] = st; // record for the moment
4046 if (st_size < BytesPerLong) // something has changed
4047 ++old_subword; // includes int/float, but who's counting...
4048 else ++old_long;
4049 }
4050
4051 if ((old_subword + old_long) == 0)
4052 return; // nothing more to do
4053
4054 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4055 // Be sure to insert them before overlapping non-constant stores.
4056 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4057 for (int j = 0; j < num_tiles; j++) {
4058 jlong con = tiles[j];
4059 jlong init = inits[j];
4060 if (con == 0) continue;
4061 jint con0, con1; // split the constant, address-wise
4062 jint init0, init1; // split the init map, address-wise
4063 { union { jlong con; jint intcon[2]; } u;
4064 u.con = con;
4065 con0 = u.intcon[0];
4066 con1 = u.intcon[1];
4067 u.con = init;
4068 init0 = u.intcon[0];
4069 init1 = u.intcon[1];
4070 }
4071
4072 Node* old = nodes[j];
4073 assert(old != NULL, "need the prior store");
4074 intptr_t offset = (j * BytesPerLong);
4075
4076 bool split = !Matcher::isSimpleConstant64(con);
4077
4078 if (offset < header_size) {
4079 assert(offset + BytesPerInt >= header_size, "second int counts");
4080 assert(*(jint*)&tiles[j] == 0, "junk in header");
4081 split = true; // only the second word counts
4082 // Example: int a[] = { 42 ... }
4083 } else if (con0 == 0 && init0 == -1) {
4084 split = true; // first word is covered by full inits
4085 // Example: int a[] = { ... foo(), 42 ... }
4086 } else if (con1 == 0 && init1 == -1) {
4087 split = true; // second word is covered by full inits
4088 // Example: int a[] = { ... 42, foo() ... }
4089 }
4090
4091 // Here's a case where init0 is neither 0 nor -1:
4092 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4093 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4094 // In this case the tile is not split; it is (jlong)42.
4095 // The big tile is stored down, and then the foo() value is inserted.
4096 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4097
4098 Node* ctl = old->in(MemNode::Control);
4099 Node* adr = make_raw_address(offset, phase);
4100 const TypePtr* atp = TypeRawPtr::BOTTOM;
4101
4102 // One or two coalesced stores to plop down.
4103 Node* st[2];
4104 intptr_t off[2];
4105 int nst = 0;
4106 if (!split) {
4107 ++new_long;
4108 off[nst] = offset;
4109 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4110 phase->longcon(con), T_LONG, MemNode::unordered);
4111 } else {
4112 // Omit either if it is a zero.
4113 if (con0 != 0) {
4114 ++new_int;
4115 off[nst] = offset;
4116 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4117 phase->intcon(con0), T_INT, MemNode::unordered);
4118 }
4119 if (con1 != 0) {
4120 ++new_int;
4121 offset += BytesPerInt;
4122 adr = make_raw_address(offset, phase);
4123 off[nst] = offset;
4124 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4125 phase->intcon(con1), T_INT, MemNode::unordered);
4126 }
4127 }
4128
4129 // Insert second store first, then the first before the second.
4130 // Insert each one just before any overlapping non-constant stores.
4131 while (nst > 0) {
4132 Node* st1 = st[--nst];
4133 C->copy_node_notes_to(st1, old);
4134 st1 = phase->transform(st1);
4135 offset = off[nst];
4136 assert(offset >= header_size, "do not smash header");
4137 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4138 guarantee(ins_idx != 0, "must re-insert constant store");
4139 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4140 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4141 set_req(--ins_idx, st1);
4142 else
4143 ins_req(ins_idx, st1);
4144 }
4145 }
4146
4147 if (PrintCompilation && WizardMode)
4148 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4149 old_subword, old_long, new_int, new_long);
4150 if (C->log() != NULL)
4151 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4152 old_subword, old_long, new_int, new_long);
4153
4154 // Clean up any remaining occurrences of zmem:
4155 remove_extra_zeroes();
4156 }
4157
4158 // Explore forward from in(start) to find the first fully initialized
4159 // word, and return its offset. Skip groups of subword stores which
4160 // together initialize full words. If in(start) is itself part of a
4161 // fully initialized word, return the offset of in(start). If there
4162 // are no following full-word stores, or if something is fishy, return
4163 // a negative value.
4164 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4165 int int_map = 0;
4166 intptr_t int_map_off = 0;
4167 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4168
4169 for (uint i = start, limit = req(); i < limit; i++) {
4170 Node* st = in(i);
4171
4172 intptr_t st_off = get_store_offset(st, phase);
4173 if (st_off < 0) break; // return conservative answer
4174
4175 int st_size = st->as_Store()->memory_size();
4176 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4177 return st_off; // we found a complete word init
4178 }
4179
4180 // update the map:
4181
4182 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4183 if (this_int_off != int_map_off) {
4184 // reset the map:
4185 int_map = 0;
4186 int_map_off = this_int_off;
4187 }
4188
4189 int subword_off = st_off - this_int_off;
4190 int_map |= right_n_bits(st_size) << subword_off;
4191 if ((int_map & FULL_MAP) == FULL_MAP) {
4192 return this_int_off; // we found a complete word init
4193 }
4194
4195 // Did this store hit or cross the word boundary?
4196 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4197 if (next_int_off == this_int_off + BytesPerInt) {
4198 // We passed the current int, without fully initializing it.
4199 int_map_off = next_int_off;
4200 int_map >>= BytesPerInt;
4201 } else if (next_int_off > this_int_off + BytesPerInt) {
4202 // We passed the current and next int.
4203 return this_int_off + BytesPerInt;
4204 }
4205 }
4206
4207 return -1;
4208 }
4209
4210
4211 // Called when the associated AllocateNode is expanded into CFG.
4212 // At this point, we may perform additional optimizations.
4213 // Linearize the stores by ascending offset, to make memory
4214 // activity as coherent as possible.
4215 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4216 intptr_t header_size,
4217 Node* size_in_bytes,
4218 PhaseIterGVN* phase) {
4219 assert(!is_complete(), "not already complete");
4220 assert(stores_are_sane(phase), "");
4221 assert(allocation() != NULL, "must be present");
4222
4223 remove_extra_zeroes();
4224
4225 if (ReduceFieldZeroing || ReduceBulkZeroing)
4226 // reduce instruction count for common initialization patterns
4227 coalesce_subword_stores(header_size, size_in_bytes, phase);
4228
4229 Node* zmem = zero_memory(); // initially zero memory state
4230 Node* inits = zmem; // accumulating a linearized chain of inits
4231 #ifdef ASSERT
4232 intptr_t first_offset = allocation()->minimum_header_size();
4233 intptr_t last_init_off = first_offset; // previous init offset
4234 intptr_t last_init_end = first_offset; // previous init offset+size
4235 intptr_t last_tile_end = first_offset; // previous tile offset+size
4236 #endif
4237 intptr_t zeroes_done = header_size;
4238
4239 bool do_zeroing = true; // we might give up if inits are very sparse
4240 int big_init_gaps = 0; // how many large gaps have we seen?
4241
4242 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4243 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4244
4245 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4246 Node* st = in(i);
4247 intptr_t st_off = get_store_offset(st, phase);
4248 if (st_off < 0)
4249 break; // unknown junk in the inits
4250 if (st->in(MemNode::Memory) != zmem)
4251 break; // complicated store chains somehow in list
4252
4253 int st_size = st->as_Store()->memory_size();
4254 intptr_t next_init_off = st_off + st_size;
4255
4256 if (do_zeroing && zeroes_done < next_init_off) {
4257 // See if this store needs a zero before it or under it.
4258 intptr_t zeroes_needed = st_off;
4259
4260 if (st_size < BytesPerInt) {
4261 // Look for subword stores which only partially initialize words.
4262 // If we find some, we must lay down some word-level zeroes first,
4263 // underneath the subword stores.
4264 //
4265 // Examples:
4266 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4267 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4268 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4269 //
4270 // Note: coalesce_subword_stores may have already done this,
4271 // if it was prompted by constant non-zero subword initializers.
4272 // But this case can still arise with non-constant stores.
4273
4274 intptr_t next_full_store = find_next_fullword_store(i, phase);
4275
4276 // In the examples above:
4277 // in(i) p q r s x y z
4278 // st_off 12 13 14 15 12 13 14
4279 // st_size 1 1 1 1 1 1 1
4280 // next_full_s. 12 16 16 16 16 16 16
4281 // z's_done 12 16 16 16 12 16 12
4282 // z's_needed 12 16 16 16 16 16 16
4283 // zsize 0 0 0 0 4 0 4
4284 if (next_full_store < 0) {
4285 // Conservative tack: Zero to end of current word.
4286 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4287 } else {
4288 // Zero to beginning of next fully initialized word.
4289 // Or, don't zero at all, if we are already in that word.
4290 assert(next_full_store >= zeroes_needed, "must go forward");
4291 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4292 zeroes_needed = next_full_store;
4293 }
4294 }
4295
4296 if (zeroes_needed > zeroes_done) {
4297 intptr_t zsize = zeroes_needed - zeroes_done;
4298 // Do some incremental zeroing on rawmem, in parallel with inits.
4299 zeroes_done = align_down(zeroes_done, BytesPerInt);
4300 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4301 zeroes_done, zeroes_needed,
4302 phase);
4303 zeroes_done = zeroes_needed;
4304 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4305 do_zeroing = false; // leave the hole, next time
4306 }
4307 }
4308
4309 // Collect the store and move on:
4310 phase->replace_input_of(st, MemNode::Memory, inits);
4311 inits = st; // put it on the linearized chain
4312 set_req(i, zmem); // unhook from previous position
4313
4314 if (zeroes_done == st_off)
4315 zeroes_done = next_init_off;
4316
4317 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4318
4319 #ifdef ASSERT
4320 // Various order invariants. Weaker than stores_are_sane because
4321 // a large constant tile can be filled in by smaller non-constant stores.
4322 assert(st_off >= last_init_off, "inits do not reverse");
4323 last_init_off = st_off;
4324 const Type* val = NULL;
4325 if (st_size >= BytesPerInt &&
4326 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4327 (int)val->basic_type() < (int)T_OBJECT) {
4328 assert(st_off >= last_tile_end, "tiles do not overlap");
4329 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4330 last_tile_end = MAX2(last_tile_end, next_init_off);
4331 } else {
4332 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4333 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4334 assert(st_off >= last_init_end, "inits do not overlap");
4335 last_init_end = next_init_off; // it's a non-tile
4336 }
4337 #endif //ASSERT
4338 }
4339
4340 remove_extra_zeroes(); // clear out all the zmems left over
4341 add_req(inits);
4342
4343 if (!(UseTLAB && ZeroTLAB)) {
4344 // If anything remains to be zeroed, zero it all now.
4345 zeroes_done = align_down(zeroes_done, BytesPerInt);
4346 // if it is the last unused 4 bytes of an instance, forget about it
4347 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4348 if (zeroes_done + BytesPerLong >= size_limit) {
4349 AllocateNode* alloc = allocation();
4350 assert(alloc != NULL, "must be present");
4351 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4352 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4353 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4354 if (zeroes_done == k->layout_helper())
4355 zeroes_done = size_limit;
4356 }
4357 }
4358 if (zeroes_done < size_limit) {
4359 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4360 zeroes_done, size_in_bytes, phase);
4361 }
4362 }
4363
4364 set_complete(phase);
4365 return rawmem;
4366 }
4367
4368
4369 #ifdef ASSERT
4370 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4371 if (is_complete())
4372 return true; // stores could be anything at this point
4373 assert(allocation() != NULL, "must be present");
4374 intptr_t last_off = allocation()->minimum_header_size();
4375 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4376 Node* st = in(i);
4377 intptr_t st_off = get_store_offset(st, phase);
4378 if (st_off < 0) continue; // ignore dead garbage
4379 if (last_off > st_off) {
4380 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4381 this->dump(2);
4382 assert(false, "ascending store offsets");
4383 return false;
4384 }
4385 last_off = st_off + st->as_Store()->memory_size();
4386 }
4387 return true;
4388 }
4389 #endif //ASSERT
4390
4391
4392
4393
4394 //============================MergeMemNode=====================================
4395 //
4396 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4397 // contributing store or call operations. Each contributor provides the memory
4398 // state for a particular "alias type" (see Compile::alias_type). For example,
4399 // if a MergeMem has an input X for alias category #6, then any memory reference
4400 // to alias category #6 may use X as its memory state input, as an exact equivalent
4401 // to using the MergeMem as a whole.
4402 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4403 //
4404 // (Here, the <N> notation gives the index of the relevant adr_type.)
4405 //
4406 // In one special case (and more cases in the future), alias categories overlap.
4407 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4408 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4409 // it is exactly equivalent to that state W:
4410 // MergeMem(<Bot>: W) <==> W
4411 //
4412 // Usually, the merge has more than one input. In that case, where inputs
4413 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4414 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4415 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4416 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4417 //
4418 // A merge can take a "wide" memory state as one of its narrow inputs.
4419 // This simply means that the merge observes out only the relevant parts of
4420 // the wide input. That is, wide memory states arriving at narrow merge inputs
4421 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4422 //
4423 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4424 // and that memory slices "leak through":
4425 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4426 //
4427 // But, in such a cascade, repeated memory slices can "block the leak":
4428 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4429 //
4430 // In the last example, Y is not part of the combined memory state of the
4431 // outermost MergeMem. The system must, of course, prevent unschedulable
4432 // memory states from arising, so you can be sure that the state Y is somehow
4433 // a precursor to state Y'.
4434 //
4435 //
4436 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4437 // of each MergeMemNode array are exactly the numerical alias indexes, including
4438 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4439 // Compile::alias_type (and kin) produce and manage these indexes.
4440 //
4441 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4442 // (Note that this provides quick access to the top node inside MergeMem methods,
4443 // without the need to reach out via TLS to Compile::current.)
4444 //
4445 // As a consequence of what was just described, a MergeMem that represents a full
4446 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4447 // containing all alias categories.
4448 //
4449 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4450 //
4451 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4452 // a memory state for the alias type <N>, or else the top node, meaning that
4453 // there is no particular input for that alias type. Note that the length of
4454 // a MergeMem is variable, and may be extended at any time to accommodate new
4455 // memory states at larger alias indexes. When merges grow, they are of course
4456 // filled with "top" in the unused in() positions.
4457 //
4458 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4459 // (Top was chosen because it works smoothly with passes like GCM.)
4460 //
4461 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4462 // the type of random VM bits like TLS references.) Since it is always the
4463 // first non-Bot memory slice, some low-level loops use it to initialize an
4464 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4465 //
4466 //
4467 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4468 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4469 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4470 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4471 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4472 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4473 //
4474 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4475 // really that different from the other memory inputs. An abbreviation called
4476 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4477 //
4478 //
4479 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4480 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4481 // that "emerges though" the base memory will be marked as excluding the alias types
4482 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4483 //
4484 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4485 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4486 //
4487 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4488 // (It is currently unimplemented.) As you can see, the resulting merge is
4489 // actually a disjoint union of memory states, rather than an overlay.
4490 //
4491
4492 //------------------------------MergeMemNode-----------------------------------
4493 Node* MergeMemNode::make_empty_memory() {
4494 Node* empty_memory = (Node*) Compile::current()->top();
4495 assert(empty_memory->is_top(), "correct sentinel identity");
4496 return empty_memory;
4497 }
4498
4499 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4500 init_class_id(Class_MergeMem);
4501 // all inputs are nullified in Node::Node(int)
4502 // set_input(0, NULL); // no control input
4503
4504 // Initialize the edges uniformly to top, for starters.
4505 Node* empty_mem = make_empty_memory();
4506 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4507 init_req(i,empty_mem);
4508 }
4509 assert(empty_memory() == empty_mem, "");
4510
4511 if( new_base != NULL && new_base->is_MergeMem() ) {
4512 MergeMemNode* mdef = new_base->as_MergeMem();
4513 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4514 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4515 mms.set_memory(mms.memory2());
4516 }
4517 assert(base_memory() == mdef->base_memory(), "");
4518 } else {
4519 set_base_memory(new_base);
4520 }
4521 }
4522
4523 // Make a new, untransformed MergeMem with the same base as 'mem'.
4524 // If mem is itself a MergeMem, populate the result with the same edges.
4525 MergeMemNode* MergeMemNode::make(Node* mem) {
4526 return new MergeMemNode(mem);
4527 }
4528
4529 //------------------------------cmp--------------------------------------------
4530 uint MergeMemNode::hash() const { return NO_HASH; }
4531 uint MergeMemNode::cmp( const Node &n ) const {
4532 return (&n == this); // Always fail except on self
4533 }
4534
4535 //------------------------------Identity---------------------------------------
4536 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4537 // Identity if this merge point does not record any interesting memory
4538 // disambiguations.
4539 Node* base_mem = base_memory();
4540 Node* empty_mem = empty_memory();
4541 if (base_mem != empty_mem) { // Memory path is not dead?
4542 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4543 Node* mem = in(i);
4544 if (mem != empty_mem && mem != base_mem) {
4545 return this; // Many memory splits; no change
4546 }
4547 }
4548 }
4549 return base_mem; // No memory splits; ID on the one true input
4550 }
4551
4552 //------------------------------Ideal------------------------------------------
4553 // This method is invoked recursively on chains of MergeMem nodes
4554 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4555 // Remove chain'd MergeMems
4556 //
4557 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4558 // relative to the "in(Bot)". Since we are patching both at the same time,
4559 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4560 // but rewrite each "in(i)" relative to the new "in(Bot)".
4561 Node *progress = NULL;
4562
4563
4564 Node* old_base = base_memory();
4565 Node* empty_mem = empty_memory();
4566 if (old_base == empty_mem)
4567 return NULL; // Dead memory path.
4568
4569 MergeMemNode* old_mbase;
4570 if (old_base != NULL && old_base->is_MergeMem())
4571 old_mbase = old_base->as_MergeMem();
4572 else
4573 old_mbase = NULL;
4574 Node* new_base = old_base;
4575
4576 // simplify stacked MergeMems in base memory
4577 if (old_mbase) new_base = old_mbase->base_memory();
4578
4579 // the base memory might contribute new slices beyond my req()
4580 if (old_mbase) grow_to_match(old_mbase);
4581
4582 // Look carefully at the base node if it is a phi.
4583 PhiNode* phi_base;
4584 if (new_base != NULL && new_base->is_Phi())
4585 phi_base = new_base->as_Phi();
4586 else
4587 phi_base = NULL;
4588
4589 Node* phi_reg = NULL;
4590 uint phi_len = (uint)-1;
4591 if (phi_base != NULL && !phi_base->is_copy()) {
4592 // do not examine phi if degraded to a copy
4593 phi_reg = phi_base->region();
4594 phi_len = phi_base->req();
4595 // see if the phi is unfinished
4596 for (uint i = 1; i < phi_len; i++) {
4597 if (phi_base->in(i) == NULL) {
4598 // incomplete phi; do not look at it yet!
4599 phi_reg = NULL;
4600 phi_len = (uint)-1;
4601 break;
4602 }
4603 }
4604 }
4605
4606 // Note: We do not call verify_sparse on entry, because inputs
4607 // can normalize to the base_memory via subsume_node or similar
4608 // mechanisms. This method repairs that damage.
4609
4610 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4611
4612 // Look at each slice.
4613 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4614 Node* old_in = in(i);
4615 // calculate the old memory value
4616 Node* old_mem = old_in;
4617 if (old_mem == empty_mem) old_mem = old_base;
4618 assert(old_mem == memory_at(i), "");
4619
4620 // maybe update (reslice) the old memory value
4621
4622 // simplify stacked MergeMems
4623 Node* new_mem = old_mem;
4624 MergeMemNode* old_mmem;
4625 if (old_mem != NULL && old_mem->is_MergeMem())
4626 old_mmem = old_mem->as_MergeMem();
4627 else
4628 old_mmem = NULL;
4629 if (old_mmem == this) {
4630 // This can happen if loops break up and safepoints disappear.
4631 // A merge of BotPtr (default) with a RawPtr memory derived from a
4632 // safepoint can be rewritten to a merge of the same BotPtr with
4633 // the BotPtr phi coming into the loop. If that phi disappears
4634 // also, we can end up with a self-loop of the mergemem.
4635 // In general, if loops degenerate and memory effects disappear,
4636 // a mergemem can be left looking at itself. This simply means
4637 // that the mergemem's default should be used, since there is
4638 // no longer any apparent effect on this slice.
4639 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4640 // from start. Update the input to TOP.
4641 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4642 }
4643 else if (old_mmem != NULL) {
4644 new_mem = old_mmem->memory_at(i);
4645 }
4646 // else preceding memory was not a MergeMem
4647
4648 // maybe store down a new value
4649 Node* new_in = new_mem;
4650 if (new_in == new_base) new_in = empty_mem;
4651
4652 if (new_in != old_in) {
4653 // Warning: Do not combine this "if" with the previous "if"
4654 // A memory slice might have be be rewritten even if it is semantically
4655 // unchanged, if the base_memory value has changed.
4656 set_req(i, new_in);
4657 progress = this; // Report progress
4658 }
4659 }
4660
4661 if (new_base != old_base) {
4662 set_req(Compile::AliasIdxBot, new_base);
4663 // Don't use set_base_memory(new_base), because we need to update du.
4664 assert(base_memory() == new_base, "");
4665 progress = this;
4666 }
4667
4668 if( base_memory() == this ) {
4669 // a self cycle indicates this memory path is dead
4670 set_req(Compile::AliasIdxBot, empty_mem);
4671 }
4672
4673 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4674 // Recursion must occur after the self cycle check above
4675 if( base_memory()->is_MergeMem() ) {
4676 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4677 Node *m = phase->transform(new_mbase); // Rollup any cycles
4678 if( m != NULL &&
4679 (m->is_top() ||
4680 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4681 // propagate rollup of dead cycle to self
4682 set_req(Compile::AliasIdxBot, empty_mem);
4683 }
4684 }
4685
4686 if( base_memory() == empty_mem ) {
4687 progress = this;
4688 // Cut inputs during Parse phase only.
4689 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4690 if( !can_reshape ) {
4691 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4692 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4693 }
4694 }
4695 }
4696
4697 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4698 // Check if PhiNode::Ideal's "Split phis through memory merges"
4699 // transform should be attempted. Look for this->phi->this cycle.
4700 uint merge_width = req();
4701 if (merge_width > Compile::AliasIdxRaw) {
4702 PhiNode* phi = base_memory()->as_Phi();
4703 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4704 if (phi->in(i) == this) {
4705 phase->is_IterGVN()->_worklist.push(phi);
4706 break;
4707 }
4708 }
4709 }
4710 }
4711
4712 assert(progress || verify_sparse(), "please, no dups of base");
4713 return progress;
4714 }
4715
4716 //-------------------------set_base_memory-------------------------------------
4717 void MergeMemNode::set_base_memory(Node *new_base) {
4718 Node* empty_mem = empty_memory();
4719 set_req(Compile::AliasIdxBot, new_base);
4720 assert(memory_at(req()) == new_base, "must set default memory");
4721 // Clear out other occurrences of new_base:
4722 if (new_base != empty_mem) {
4723 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4724 if (in(i) == new_base) set_req(i, empty_mem);
4725 }
4726 }
4727 }
4728
4729 //------------------------------out_RegMask------------------------------------
4730 const RegMask &MergeMemNode::out_RegMask() const {
4731 return RegMask::Empty;
4732 }
4733
4734 //------------------------------dump_spec--------------------------------------
4735 #ifndef PRODUCT
4736 void MergeMemNode::dump_spec(outputStream *st) const {
4737 st->print(" {");
4738 Node* base_mem = base_memory();
4739 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4740 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4741 if (mem == base_mem) { st->print(" -"); continue; }
4742 st->print( " N%d:", mem->_idx );
4743 Compile::current()->get_adr_type(i)->dump_on(st);
4744 }
4745 st->print(" }");
4746 }
4747 #endif // !PRODUCT
4748
4749
4750 #ifdef ASSERT
4751 static bool might_be_same(Node* a, Node* b) {
4752 if (a == b) return true;
4753 if (!(a->is_Phi() || b->is_Phi())) return false;
4754 // phis shift around during optimization
4755 return true; // pretty stupid...
4756 }
4757
4758 // verify a narrow slice (either incoming or outgoing)
4759 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4760 if (!VerifyAliases) return; // don't bother to verify unless requested
4761 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4762 if (Node::in_dump()) return; // muzzle asserts when printing
4763 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4764 assert(n != NULL, "");
4765 // Elide intervening MergeMem's
4766 while (n->is_MergeMem()) {
4767 n = n->as_MergeMem()->memory_at(alias_idx);
4768 }
4769 Compile* C = Compile::current();
4770 const TypePtr* n_adr_type = n->adr_type();
4771 if (n == m->empty_memory()) {
4772 // Implicit copy of base_memory()
4773 } else if (n_adr_type != TypePtr::BOTTOM) {
4774 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4775 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4776 } else {
4777 // A few places like make_runtime_call "know" that VM calls are narrow,
4778 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4779 bool expected_wide_mem = false;
4780 if (n == m->base_memory()) {
4781 expected_wide_mem = true;
4782 } else if (alias_idx == Compile::AliasIdxRaw ||
4783 n == m->memory_at(Compile::AliasIdxRaw)) {
4784 expected_wide_mem = true;
4785 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4786 // memory can "leak through" calls on channels that
4787 // are write-once. Allow this also.
4788 expected_wide_mem = true;
4789 }
4790 assert(expected_wide_mem, "expected narrow slice replacement");
4791 }
4792 }
4793 #else // !ASSERT
4794 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4795 #endif
4796
4797
4798 //-----------------------------memory_at---------------------------------------
4799 Node* MergeMemNode::memory_at(uint alias_idx) const {
4800 assert(alias_idx >= Compile::AliasIdxRaw ||
4801 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4802 "must avoid base_memory and AliasIdxTop");
4803
4804 // Otherwise, it is a narrow slice.
4805 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4806 Compile *C = Compile::current();
4807 if (is_empty_memory(n)) {
4808 // the array is sparse; empty slots are the "top" node
4809 n = base_memory();
4810 assert(Node::in_dump()
4811 || n == NULL || n->bottom_type() == Type::TOP
4812 || n->adr_type() == NULL // address is TOP
4813 || n->adr_type() == TypePtr::BOTTOM
4814 || n->adr_type() == TypeRawPtr::BOTTOM
4815 || Compile::current()->AliasLevel() == 0,
4816 "must be a wide memory");
4817 // AliasLevel == 0 if we are organizing the memory states manually.
4818 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4819 } else {
4820 // make sure the stored slice is sane
4821 #ifdef ASSERT
4822 if (VMError::is_error_reported() || Node::in_dump()) {
4823 } else if (might_be_same(n, base_memory())) {
4824 // Give it a pass: It is a mostly harmless repetition of the base.
4825 // This can arise normally from node subsumption during optimization.
4826 } else {
4827 verify_memory_slice(this, alias_idx, n);
4828 }
4829 #endif
4830 }
4831 return n;
4832 }
4833
4834 //---------------------------set_memory_at-------------------------------------
4835 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4836 verify_memory_slice(this, alias_idx, n);
4837 Node* empty_mem = empty_memory();
4838 if (n == base_memory()) n = empty_mem; // collapse default
4839 uint need_req = alias_idx+1;
4840 if (req() < need_req) {
4841 if (n == empty_mem) return; // already the default, so do not grow me
4842 // grow the sparse array
4843 do {
4844 add_req(empty_mem);
4845 } while (req() < need_req);
4846 }
4847 set_req( alias_idx, n );
4848 }
4849
4850
4851
4852 //--------------------------iteration_setup------------------------------------
4853 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4854 if (other != NULL) {
4855 grow_to_match(other);
4856 // invariant: the finite support of mm2 is within mm->req()
4857 #ifdef ASSERT
4858 for (uint i = req(); i < other->req(); i++) {
4859 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4860 }
4861 #endif
4862 }
4863 // Replace spurious copies of base_memory by top.
4864 Node* base_mem = base_memory();
4865 if (base_mem != NULL && !base_mem->is_top()) {
4866 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4867 if (in(i) == base_mem)
4868 set_req(i, empty_memory());
4869 }
4870 }
4871 }
4872
4873 //---------------------------grow_to_match-------------------------------------
4874 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4875 Node* empty_mem = empty_memory();
4876 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4877 // look for the finite support of the other memory
4878 for (uint i = other->req(); --i >= req(); ) {
4879 if (other->in(i) != empty_mem) {
4880 uint new_len = i+1;
4881 while (req() < new_len) add_req(empty_mem);
4882 break;
4883 }
4884 }
4885 }
4886
4887 //---------------------------verify_sparse-------------------------------------
4888 #ifndef PRODUCT
4889 bool MergeMemNode::verify_sparse() const {
4890 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4891 Node* base_mem = base_memory();
4892 // The following can happen in degenerate cases, since empty==top.
4893 if (is_empty_memory(base_mem)) return true;
4894 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4895 assert(in(i) != NULL, "sane slice");
4896 if (in(i) == base_mem) return false; // should have been the sentinel value!
4897 }
4898 return true;
4899 }
4900
4901 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4902 Node* n;
4903 n = mm->in(idx);
4904 if (mem == n) return true; // might be empty_memory()
4905 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4906 if (mem == n) return true;
4907 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4908 if (mem == n) return true;
4909 if (n == NULL) break;
4910 }
4911 return false;
4912 }
4913 #endif // !PRODUCT