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