1 /*
2 * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "memory/allocation.inline.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "oops/objArrayKlass.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/arraycopynode.hpp"
35 #include "opto/cfgnode.hpp"
36 #include "opto/compile.hpp"
37 #include "opto/connode.hpp"
38 #include "opto/convertnode.hpp"
39 #include "opto/loopnode.hpp"
40 #include "opto/machnode.hpp"
41 #include "opto/matcher.hpp"
42 #include "opto/memnode.hpp"
43 #include "opto/mulnode.hpp"
44 #include "opto/narrowptrnode.hpp"
45 #include "opto/phaseX.hpp"
46 #include "opto/regmask.hpp"
47 #include "opto/rootnode.hpp"
48 #include "opto/valuetypenode.hpp"
49 #include "utilities/align.hpp"
50 #include "utilities/copy.hpp"
51 #include "utilities/macros.hpp"
52 #include "utilities/vmError.hpp"
53 #if INCLUDE_ZGC
54 #include "gc/z/c2/zBarrierSetC2.hpp"
55 #endif
56
57 // Portions of code courtesy of Clifford Click
58
59 // Optimization - Graph Style
60
61 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
62
63 //=============================================================================
64 uint MemNode::size_of() const { return sizeof(*this); }
65
66 const TypePtr *MemNode::adr_type() const {
67 Node* adr = in(Address);
68 if (adr == NULL) return NULL; // node is dead
69 const TypePtr* cross_check = NULL;
70 DEBUG_ONLY(cross_check = _adr_type);
71 return calculate_adr_type(adr->bottom_type(), cross_check);
72 }
73
74 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
75 if (adr != NULL) {
76 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
77 return true;
78 }
79 }
80 return false;
81 }
82
83 #ifndef PRODUCT
84 void MemNode::dump_spec(outputStream *st) const {
85 if (in(Address) == NULL) return; // node is dead
86 #ifndef ASSERT
87 // fake the missing field
88 const TypePtr* _adr_type = NULL;
89 if (in(Address) != NULL)
90 _adr_type = in(Address)->bottom_type()->isa_ptr();
91 #endif
92 dump_adr_type(this, _adr_type, st);
93
94 Compile* C = Compile::current();
95 if (C->alias_type(_adr_type)->is_volatile()) {
96 st->print(" Volatile!");
97 }
98 if (_unaligned_access) {
99 st->print(" unaligned");
100 }
101 if (_mismatched_access) {
102 st->print(" mismatched");
103 }
104 if (_unsafe_access) {
105 st->print(" unsafe");
106 }
107 }
108
109 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
110 st->print(" @");
111 if (adr_type == NULL) {
112 st->print("NULL");
113 } else {
114 adr_type->dump_on(st);
115 Compile* C = Compile::current();
116 Compile::AliasType* atp = NULL;
117 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
118 if (atp == NULL)
119 st->print(", idx=?\?;");
120 else if (atp->index() == Compile::AliasIdxBot)
121 st->print(", idx=Bot;");
122 else if (atp->index() == Compile::AliasIdxTop)
123 st->print(", idx=Top;");
124 else if (atp->index() == Compile::AliasIdxRaw)
125 st->print(", idx=Raw;");
126 else {
127 ciField* field = atp->field();
128 if (field) {
129 st->print(", name=");
130 field->print_name_on(st);
131 }
132 st->print(", idx=%d;", atp->index());
133 }
134 }
135 }
136
137 extern void print_alias_types();
138
139 #endif
140
141 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
142 assert((t_oop != NULL), "sanity");
143 bool is_instance = t_oop->is_known_instance_field();
144 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
145 (load != NULL) && load->is_Load() &&
146 (phase->is_IterGVN() != NULL);
147 if (!(is_instance || is_boxed_value_load))
148 return mchain; // don't try to optimize non-instance types
149 uint instance_id = t_oop->instance_id();
150 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
151 Node *prev = NULL;
152 Node *result = mchain;
153 while (prev != result) {
154 prev = result;
155 if (result == start_mem)
156 break; // hit one of our sentinels
157 // skip over a call which does not affect this memory slice
158 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
159 Node *proj_in = result->in(0);
160 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
161 break; // hit one of our sentinels
162 } else if (proj_in->is_Call()) {
163 // ArrayCopyNodes processed here as well
164 CallNode *call = proj_in->as_Call();
165 if (!call->may_modify(t_oop, phase)) { // returns false for instances
166 result = call->in(TypeFunc::Memory);
167 }
168 } else if (proj_in->is_Initialize()) {
169 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
170 // Stop if this is the initialization for the object instance which
171 // contains this memory slice, otherwise skip over it.
172 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
173 break;
174 }
175 if (is_instance) {
176 result = proj_in->in(TypeFunc::Memory);
177 } else if (is_boxed_value_load) {
178 Node* klass = alloc->in(AllocateNode::KlassNode);
179 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
180 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
181 result = proj_in->in(TypeFunc::Memory); // not related allocation
182 }
183 }
184 } else if (proj_in->is_MemBar()) {
185 ArrayCopyNode* ac = NULL;
186 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
187 break;
188 }
189 result = proj_in->in(TypeFunc::Memory);
190 } else {
191 assert(false, "unexpected projection");
192 }
193 } else if (result->is_ClearArray()) {
194 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
195 // Can not bypass initialization of the instance
196 // we are looking for.
197 break;
198 }
199 // Otherwise skip it (the call updated 'result' value).
200 } else if (result->is_MergeMem()) {
201 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
202 }
203 }
204 return result;
205 }
206
207 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
208 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
209 if (t_oop == NULL)
210 return mchain; // don't try to optimize non-oop types
211 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
212 bool is_instance = t_oop->is_known_instance_field();
213 PhaseIterGVN *igvn = phase->is_IterGVN();
214 if (is_instance && igvn != NULL && result->is_Phi()) {
215 PhiNode *mphi = result->as_Phi();
216 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
217 const TypePtr *t = mphi->adr_type();
218 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
219 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
220 t->is_oopptr()->cast_to_exactness(true)
221 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
222 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
223 // clone the Phi with our address type
224 result = mphi->split_out_instance(t_adr, igvn);
225 } else {
226 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
227 }
228 }
229 return result;
230 }
231
232 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
233 uint alias_idx = phase->C->get_alias_index(tp);
234 Node *mem = mmem;
235 #ifdef ASSERT
236 {
237 // Check that current type is consistent with the alias index used during graph construction
238 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
239 bool consistent = adr_check == NULL || adr_check->empty() ||
240 phase->C->must_alias(adr_check, alias_idx );
241 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
242 if( !consistent && adr_check != NULL && !adr_check->empty() &&
243 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
244 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
245 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
246 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
247 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
248 // don't assert if it is dead code.
249 consistent = true;
250 }
251 if( !consistent ) {
252 st->print("alias_idx==%d, adr_check==", alias_idx);
253 if( adr_check == NULL ) {
254 st->print("NULL");
255 } else {
256 adr_check->dump();
257 }
258 st->cr();
259 print_alias_types();
260 assert(consistent, "adr_check must match alias idx");
261 }
262 }
263 #endif
264 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
265 // means an array I have not precisely typed yet. Do not do any
266 // alias stuff with it any time soon.
267 const TypeOopPtr *toop = tp->isa_oopptr();
268 if( tp->base() != Type::AnyPtr &&
269 !(toop &&
270 toop->klass() != NULL &&
271 toop->klass()->is_java_lang_Object() &&
272 toop->offset() == Type::OffsetBot) ) {
273 // compress paths and change unreachable cycles to TOP
274 // If not, we can update the input infinitely along a MergeMem cycle
275 // Equivalent code in PhiNode::Ideal
276 Node* m = phase->transform(mmem);
277 // If transformed to a MergeMem, get the desired slice
278 // Otherwise the returned node represents memory for every slice
279 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
280 // Update input if it is progress over what we have now
281 }
282 return mem;
283 }
284
285 //--------------------------Ideal_common---------------------------------------
286 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
287 // Unhook non-raw memories from complete (macro-expanded) initializations.
288 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
289 // If our control input is a dead region, kill all below the region
290 Node *ctl = in(MemNode::Control);
291 if (ctl && remove_dead_region(phase, can_reshape))
292 return this;
293 ctl = in(MemNode::Control);
294 // Don't bother trying to transform a dead node
295 if (ctl && ctl->is_top()) return NodeSentinel;
296
297 PhaseIterGVN *igvn = phase->is_IterGVN();
298 // Wait if control on the worklist.
299 if (ctl && can_reshape && igvn != NULL) {
300 Node* bol = NULL;
301 Node* cmp = NULL;
302 if (ctl->in(0)->is_If()) {
303 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
304 bol = ctl->in(0)->in(1);
305 if (bol->is_Bool())
306 cmp = ctl->in(0)->in(1)->in(1);
307 }
308 if (igvn->_worklist.member(ctl) ||
309 (bol != NULL && igvn->_worklist.member(bol)) ||
310 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
311 // This control path may be dead.
312 // Delay this memory node transformation until the control is processed.
313 phase->is_IterGVN()->_worklist.push(this);
314 return NodeSentinel; // caller will return NULL
315 }
316 }
317 // Ignore if memory is dead, or self-loop
318 Node *mem = in(MemNode::Memory);
319 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
320 assert(mem != this, "dead loop in MemNode::Ideal");
321
322 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
323 // This memory slice may be dead.
324 // Delay this mem node transformation until the memory is processed.
325 phase->is_IterGVN()->_worklist.push(this);
326 return NodeSentinel; // caller will return NULL
327 }
328
329 Node *address = in(MemNode::Address);
330 const Type *t_adr = phase->type(address);
331 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
332
333 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
334 // Unsafe off-heap access with zero address. Remove access and other control users
335 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
336 assert(ctl != NULL, "unsafe accesses should be control dependent");
337 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
338 Node* u = ctl->fast_out(i);
339 if (u != ctl) {
340 igvn->rehash_node_delayed(u);
341 int nb = u->replace_edge(ctl, phase->C->top());
342 --i, imax -= nb;
343 }
344 }
345 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
346 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
347 phase->C->root()->add_req(halt);
348 return this;
349 }
350
351 if (can_reshape && igvn != NULL &&
352 (igvn->_worklist.member(address) ||
353 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
354 // The address's base and type may change when the address is processed.
355 // Delay this mem node transformation until the address is processed.
356 phase->is_IterGVN()->_worklist.push(this);
357 return NodeSentinel; // caller will return NULL
358 }
359
360 // Do NOT remove or optimize the next lines: ensure a new alias index
361 // is allocated for an oop pointer type before Escape Analysis.
362 // Note: C++ will not remove it since the call has side effect.
363 if (t_adr->isa_oopptr()) {
364 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
365 }
366
367 Node* base = NULL;
368 if (address->is_AddP()) {
369 base = address->in(AddPNode::Base);
370 }
371 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
372 !t_adr->isa_rawptr()) {
373 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
374 // Skip this node optimization if its address has TOP base.
375 return NodeSentinel; // caller will return NULL
376 }
377
378 // Avoid independent memory operations
379 Node* old_mem = mem;
380
381 // The code which unhooks non-raw memories from complete (macro-expanded)
382 // initializations was removed. After macro-expansion all stores catched
383 // by Initialize node became raw stores and there is no information
384 // which memory slices they modify. So it is unsafe to move any memory
385 // operation above these stores. Also in most cases hooked non-raw memories
386 // were already unhooked by using information from detect_ptr_independence()
387 // and find_previous_store().
388
389 if (mem->is_MergeMem()) {
390 MergeMemNode* mmem = mem->as_MergeMem();
391 const TypePtr *tp = t_adr->is_ptr();
392
393 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
394 }
395
396 if (mem != old_mem) {
397 set_req(MemNode::Memory, mem);
398 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
399 igvn->_worklist.push(old_mem);
400 }
401 if (phase->type(mem) == Type::TOP) return NodeSentinel;
402 return this;
403 }
404
405 // let the subclass continue analyzing...
406 return NULL;
407 }
408
409 // Helper function for proving some simple control dominations.
410 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
411 // Already assumes that 'dom' is available at 'sub', and that 'sub'
412 // is not a constant (dominated by the method's StartNode).
413 // Used by MemNode::find_previous_store to prove that the
414 // control input of a memory operation predates (dominates)
415 // an allocation it wants to look past.
416 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
417 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
418 return false; // Conservative answer for dead code
419
420 // Check 'dom'. Skip Proj and CatchProj nodes.
421 dom = dom->find_exact_control(dom);
422 if (dom == NULL || dom->is_top())
423 return false; // Conservative answer for dead code
424
425 if (dom == sub) {
426 // For the case when, for example, 'sub' is Initialize and the original
427 // 'dom' is Proj node of the 'sub'.
428 return false;
429 }
430
431 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
432 return true;
433
434 // 'dom' dominates 'sub' if its control edge and control edges
435 // of all its inputs dominate or equal to sub's control edge.
436
437 // Currently 'sub' is either Allocate, Initialize or Start nodes.
438 // Or Region for the check in LoadNode::Ideal();
439 // 'sub' should have sub->in(0) != NULL.
440 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
441 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
442
443 // Get control edge of 'sub'.
444 Node* orig_sub = sub;
445 sub = sub->find_exact_control(sub->in(0));
446 if (sub == NULL || sub->is_top())
447 return false; // Conservative answer for dead code
448
449 assert(sub->is_CFG(), "expecting control");
450
451 if (sub == dom)
452 return true;
453
454 if (sub->is_Start() || sub->is_Root())
455 return false;
456
457 {
458 // Check all control edges of 'dom'.
459
460 ResourceMark rm;
461 Arena* arena = Thread::current()->resource_area();
462 Node_List nlist(arena);
463 Unique_Node_List dom_list(arena);
464
465 dom_list.push(dom);
466 bool only_dominating_controls = false;
467
468 for (uint next = 0; next < dom_list.size(); next++) {
469 Node* n = dom_list.at(next);
470 if (n == orig_sub)
471 return false; // One of dom's inputs dominated by sub.
472 if (!n->is_CFG() && n->pinned()) {
473 // Check only own control edge for pinned non-control nodes.
474 n = n->find_exact_control(n->in(0));
475 if (n == NULL || n->is_top())
476 return false; // Conservative answer for dead code
477 assert(n->is_CFG(), "expecting control");
478 dom_list.push(n);
479 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
480 only_dominating_controls = true;
481 } else if (n->is_CFG()) {
482 if (n->dominates(sub, nlist))
483 only_dominating_controls = true;
484 else
485 return false;
486 } else {
487 // First, own control edge.
488 Node* m = n->find_exact_control(n->in(0));
489 if (m != NULL) {
490 if (m->is_top())
491 return false; // Conservative answer for dead code
492 dom_list.push(m);
493 }
494 // Now, the rest of edges.
495 uint cnt = n->req();
496 for (uint i = 1; i < cnt; i++) {
497 m = n->find_exact_control(n->in(i));
498 if (m == NULL || m->is_top())
499 continue;
500 dom_list.push(m);
501 }
502 }
503 }
504 return only_dominating_controls;
505 }
506 }
507
508 //---------------------detect_ptr_independence---------------------------------
509 // Used by MemNode::find_previous_store to prove that two base
510 // pointers are never equal.
511 // The pointers are accompanied by their associated allocations,
512 // if any, which have been previously discovered by the caller.
513 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
514 Node* p2, AllocateNode* a2,
515 PhaseTransform* phase) {
516 // Attempt to prove that these two pointers cannot be aliased.
517 // They may both manifestly be allocations, and they should differ.
518 // Or, if they are not both allocations, they can be distinct constants.
519 // Otherwise, one is an allocation and the other a pre-existing value.
520 if (a1 == NULL && a2 == NULL) { // neither an allocation
521 return (p1 != p2) && p1->is_Con() && p2->is_Con();
522 } else if (a1 != NULL && a2 != NULL) { // both allocations
523 return (a1 != a2);
524 } else if (a1 != NULL) { // one allocation a1
525 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
526 return all_controls_dominate(p2, a1);
527 } else { //(a2 != NULL) // one allocation a2
528 return all_controls_dominate(p1, a2);
529 }
530 return false;
531 }
532
533
534 // Find an arraycopy that must have set (can_see_stored_value=true) or
535 // could have set (can_see_stored_value=false) the value for this load
536 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
537 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
538 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
539 Node* mb = mem->in(0);
540 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
541 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
542 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
543 if (ac->is_clonebasic()) {
544 intptr_t offset;
545 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
546 if (alloc != NULL && alloc == ld_alloc) {
547 return ac;
548 }
549 }
550 }
551 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
552 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
553
554 if (ac->is_arraycopy_validated() ||
555 ac->is_copyof_validated() ||
556 ac->is_copyofrange_validated()) {
557 Node* ld_addp = in(MemNode::Address);
558 if (ld_addp->is_AddP()) {
559 Node* ld_base = ld_addp->in(AddPNode::Address);
560 Node* ld_offs = ld_addp->in(AddPNode::Offset);
561
562 Node* dest = ac->in(ArrayCopyNode::Dest);
563
564 if (dest == ld_base) {
565 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
566 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
567 return ac;
568 }
569 if (!can_see_stored_value) {
570 mem = ac->in(TypeFunc::Memory);
571 }
572 }
573 }
574 }
575 }
576 return NULL;
577 }
578
579 // The logic for reordering loads and stores uses four steps:
580 // (a) Walk carefully past stores and initializations which we
581 // can prove are independent of this load.
582 // (b) Observe that the next memory state makes an exact match
583 // with self (load or store), and locate the relevant store.
584 // (c) Ensure that, if we were to wire self directly to the store,
585 // the optimizer would fold it up somehow.
586 // (d) Do the rewiring, and return, depending on some other part of
587 // the optimizer to fold up the load.
588 // This routine handles steps (a) and (b). Steps (c) and (d) are
589 // specific to loads and stores, so they are handled by the callers.
590 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
591 //
592 Node* MemNode::find_previous_store(PhaseTransform* phase) {
593 Node* ctrl = in(MemNode::Control);
594 Node* adr = in(MemNode::Address);
595 intptr_t offset = 0;
596 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
597 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
598
599 if (offset == Type::OffsetBot)
600 return NULL; // cannot unalias unless there are precise offsets
601
602 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
603 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
604
605 intptr_t size_in_bytes = memory_size();
606
607 Node* mem = in(MemNode::Memory); // start searching here...
608
609 int cnt = 50; // Cycle limiter
610 for (;;) { // While we can dance past unrelated stores...
611 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
612
613 Node* prev = mem;
614 if (mem->is_Store()) {
615 Node* st_adr = mem->in(MemNode::Address);
616 intptr_t st_offset = 0;
617 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
618 if (st_base == NULL)
619 break; // inscrutable pointer
620
621 // For raw accesses it's not enough to prove that constant offsets don't intersect.
622 // We need the bases to be the equal in order for the offset check to make sense.
623 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
624 break;
625 }
626
627 if (st_offset != offset && st_offset != Type::OffsetBot) {
628 const int MAX_STORE = BytesPerLong;
629 if (st_offset >= offset + size_in_bytes ||
630 st_offset <= offset - MAX_STORE ||
631 st_offset <= offset - mem->as_Store()->memory_size()) {
632 // Success: The offsets are provably independent.
633 // (You may ask, why not just test st_offset != offset and be done?
634 // The answer is that stores of different sizes can co-exist
635 // in the same sequence of RawMem effects. We sometimes initialize
636 // a whole 'tile' of array elements with a single jint or jlong.)
637 mem = mem->in(MemNode::Memory);
638 continue; // (a) advance through independent store memory
639 }
640 }
641 if (st_base != base &&
642 detect_ptr_independence(base, alloc,
643 st_base,
644 AllocateNode::Ideal_allocation(st_base, phase),
645 phase)) {
646 // Success: The bases are provably independent.
647 mem = mem->in(MemNode::Memory);
648 continue; // (a) advance through independent store memory
649 }
650
651 // (b) At this point, if the bases or offsets do not agree, we lose,
652 // since we have not managed to prove 'this' and 'mem' independent.
653 if (st_base == base && st_offset == offset) {
654 return mem; // let caller handle steps (c), (d)
655 }
656
657 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
658 InitializeNode* st_init = mem->in(0)->as_Initialize();
659 AllocateNode* st_alloc = st_init->allocation();
660 if (st_alloc == NULL)
661 break; // something degenerated
662 bool known_identical = false;
663 bool known_independent = false;
664 if (alloc == st_alloc)
665 known_identical = true;
666 else if (alloc != NULL)
667 known_independent = true;
668 else if (all_controls_dominate(this, st_alloc))
669 known_independent = true;
670
671 if (known_independent) {
672 // The bases are provably independent: Either they are
673 // manifestly distinct allocations, or else the control
674 // of this load dominates the store's allocation.
675 int alias_idx = phase->C->get_alias_index(adr_type());
676 if (alias_idx == Compile::AliasIdxRaw) {
677 mem = st_alloc->in(TypeFunc::Memory);
678 } else {
679 mem = st_init->memory(alias_idx);
680 }
681 continue; // (a) advance through independent store memory
682 }
683
684 // (b) at this point, if we are not looking at a store initializing
685 // the same allocation we are loading from, we lose.
686 if (known_identical) {
687 // From caller, can_see_stored_value will consult find_captured_store.
688 return mem; // let caller handle steps (c), (d)
689 }
690
691 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
692 if (prev != mem) {
693 // Found an arraycopy but it doesn't affect that load
694 continue;
695 }
696 // Found an arraycopy that may affect that load
697 return mem;
698 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
699 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
700 if (mem->is_Proj() && mem->in(0)->is_Call()) {
701 // ArrayCopyNodes processed here as well.
702 CallNode *call = mem->in(0)->as_Call();
703 if (!call->may_modify(addr_t, phase)) {
704 mem = call->in(TypeFunc::Memory);
705 continue; // (a) advance through independent call memory
706 }
707 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
708 ArrayCopyNode* ac = NULL;
709 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
710 break;
711 }
712 mem = mem->in(0)->in(TypeFunc::Memory);
713 continue; // (a) advance through independent MemBar memory
714 } else if (mem->is_ClearArray()) {
715 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
716 // (the call updated 'mem' value)
717 continue; // (a) advance through independent allocation memory
718 } else {
719 // Can not bypass initialization of the instance
720 // we are looking for.
721 return mem;
722 }
723 } else if (mem->is_MergeMem()) {
724 int alias_idx = phase->C->get_alias_index(adr_type());
725 mem = mem->as_MergeMem()->memory_at(alias_idx);
726 continue; // (a) advance through independent MergeMem memory
727 }
728 }
729
730 // Unless there is an explicit 'continue', we must bail out here,
731 // because 'mem' is an inscrutable memory state (e.g., a call).
732 break;
733 }
734
735 return NULL; // bail out
736 }
737
738 //----------------------calculate_adr_type-------------------------------------
739 // Helper function. Notices when the given type of address hits top or bottom.
740 // Also, asserts a cross-check of the type against the expected address type.
741 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
742 if (t == Type::TOP) return NULL; // does not touch memory any more?
743 #ifdef PRODUCT
744 cross_check = NULL;
745 #else
746 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
747 #endif
748 const TypePtr* tp = t->isa_ptr();
749 if (tp == NULL) {
750 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
751 return TypePtr::BOTTOM; // touches lots of memory
752 } else {
753 #ifdef ASSERT
754 // %%%% [phh] We don't check the alias index if cross_check is
755 // TypeRawPtr::BOTTOM. Needs to be investigated.
756 if (cross_check != NULL &&
757 cross_check != TypePtr::BOTTOM &&
758 cross_check != TypeRawPtr::BOTTOM) {
759 // Recheck the alias index, to see if it has changed (due to a bug).
760 Compile* C = Compile::current();
761 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
762 "must stay in the original alias category");
763 // The type of the address must be contained in the adr_type,
764 // disregarding "null"-ness.
765 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
766 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
767 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
768 "real address must not escape from expected memory type");
769 }
770 #endif
771 return tp;
772 }
773 }
774
775 //=============================================================================
776 // Should LoadNode::Ideal() attempt to remove control edges?
777 bool LoadNode::can_remove_control() const {
778 return true;
779 }
780 uint LoadNode::size_of() const { return sizeof(*this); }
781 bool LoadNode::cmp( const Node &n ) const
782 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
783 const Type *LoadNode::bottom_type() const { return _type; }
784 uint LoadNode::ideal_reg() const {
785 return _type->ideal_reg();
786 }
787
788 #ifndef PRODUCT
789 void LoadNode::dump_spec(outputStream *st) const {
790 MemNode::dump_spec(st);
791 if( !Verbose && !WizardMode ) {
792 // standard dump does this in Verbose and WizardMode
793 st->print(" #"); _type->dump_on(st);
794 }
795 if (!depends_only_on_test()) {
796 st->print(" (does not depend only on test)");
797 }
798 }
799 #endif
800
801 #ifdef ASSERT
802 //----------------------------is_immutable_value-------------------------------
803 // Helper function to allow a raw load without control edge for some cases
804 bool LoadNode::is_immutable_value(Node* adr) {
805 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
806 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
807 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
808 in_bytes(JavaThread::osthread_offset())));
809 }
810 #endif
811
812 //----------------------------LoadNode::make-----------------------------------
813 // Polymorphic factory method:
814 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
815 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
816 Compile* C = gvn.C;
817
818 // sanity check the alias category against the created node type
819 assert(!(adr_type->isa_oopptr() &&
820 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
821 "use LoadKlassNode instead");
822 assert(!(adr_type->isa_aryptr() &&
823 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
824 "use LoadRangeNode instead");
825 // Check control edge of raw loads
826 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
827 // oop will be recorded in oop map if load crosses safepoint
828 rt->isa_oopptr() || is_immutable_value(adr),
829 "raw memory operations should have control edge");
830 LoadNode* load = NULL;
831 switch (bt) {
832 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
833 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
834 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
835 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
836 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
837 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
838 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
839 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
840 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
841 case T_VALUETYPE:
842 case T_OBJECT:
843 #ifdef _LP64
844 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
845 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
846 } else
847 #endif
848 {
849 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
850 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
851 }
852 break;
853 default:
854 ShouldNotReachHere();
855 break;
856 }
857 assert(load != NULL, "LoadNode should have been created");
858 if (unaligned) {
859 load->set_unaligned_access();
860 }
861 if (mismatched) {
862 load->set_mismatched_access();
863 }
864 if (unsafe) {
865 load->set_unsafe_access();
866 }
867 if (load->Opcode() == Op_LoadN) {
868 Node* ld = gvn.transform(load);
869 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
870 }
871
872 return load;
873 }
874
875 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
876 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
877 bool require_atomic = true;
878 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
879 if (unaligned) {
880 load->set_unaligned_access();
881 }
882 if (mismatched) {
883 load->set_mismatched_access();
884 }
885 if (unsafe) {
886 load->set_unsafe_access();
887 }
888 return load;
889 }
890
891 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
892 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe) {
893 bool require_atomic = true;
894 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
895 if (unaligned) {
896 load->set_unaligned_access();
897 }
898 if (mismatched) {
899 load->set_mismatched_access();
900 }
901 if (unsafe) {
902 load->set_unsafe_access();
903 }
904 return load;
905 }
906
907
908
909 //------------------------------hash-------------------------------------------
910 uint LoadNode::hash() const {
911 // unroll addition of interesting fields
912 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
913 }
914
915 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
916 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
917 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
918 bool is_stable_ary = FoldStableValues &&
919 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
920 tp->isa_aryptr()->is_stable();
921
922 return (eliminate_boxing && non_volatile) || is_stable_ary;
923 }
924
925 return false;
926 }
927
928 // Is the value loaded previously stored by an arraycopy? If so return
929 // a load node that reads from the source array so we may be able to
930 // optimize out the ArrayCopy node later.
931 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
932 Node* ld_adr = in(MemNode::Address);
933 intptr_t ld_off = 0;
934 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
935 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
936 if (ac != NULL) {
937 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
938
939 Node* mem = ac->in(TypeFunc::Memory);
940 Node* ctl = ac->in(0);
941 Node* src = ac->in(ArrayCopyNode::Src);
942
943 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
944 return NULL;
945 }
946
947 LoadNode* ld = clone()->as_Load();
948 Node* addp = in(MemNode::Address)->clone();
949 if (ac->as_ArrayCopy()->is_clonebasic()) {
950 assert(ld_alloc != NULL, "need an alloc");
951 assert(addp->is_AddP(), "address must be addp");
952 assert(ac->in(ArrayCopyNode::Dest)->is_AddP(), "dest must be an address");
953 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
954 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base)), "strange pattern");
955 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address)), "strange pattern");
956 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
957 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
958 } else {
959 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
960 ac->as_ArrayCopy()->is_copyof_validated() ||
961 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
962 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
963 addp->set_req(AddPNode::Base, src);
964 addp->set_req(AddPNode::Address, src);
965
966 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
967 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
968 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
969 uint shift = exact_log2(type2aelembytes(ary_elem));
970
971 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
972 #ifdef _LP64
973 diff = phase->transform(new ConvI2LNode(diff));
974 #endif
975 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
976
977 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
978 addp->set_req(AddPNode::Offset, offset);
979 }
980 addp = phase->transform(addp);
981 #ifdef ASSERT
982 const TypePtr* adr_type = phase->type(addp)->is_ptr();
983 ld->_adr_type = adr_type;
984 #endif
985 ld->set_req(MemNode::Address, addp);
986 ld->set_req(0, ctl);
987 ld->set_req(MemNode::Memory, mem);
988 // load depends on the tests that validate the arraycopy
989 ld->_control_dependency = UnknownControl;
990 return ld;
991 }
992 return NULL;
993 }
994
995
996 //---------------------------can_see_stored_value------------------------------
997 // This routine exists to make sure this set of tests is done the same
998 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
999 // will change the graph shape in a way which makes memory alive twice at the
1000 // same time (uses the Oracle model of aliasing), then some
1001 // LoadXNode::Identity will fold things back to the equivalence-class model
1002 // of aliasing.
1003 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1004 Node* ld_adr = in(MemNode::Address);
1005 intptr_t ld_off = 0;
1006 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1007 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1008 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1009 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1010 // This is more general than load from boxing objects.
1011 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1012 uint alias_idx = atp->index();
1013 bool final = !atp->is_rewritable();
1014 Node* result = NULL;
1015 Node* current = st;
1016 // Skip through chains of MemBarNodes checking the MergeMems for
1017 // new states for the slice of this load. Stop once any other
1018 // kind of node is encountered. Loads from final memory can skip
1019 // through any kind of MemBar but normal loads shouldn't skip
1020 // through MemBarAcquire since the could allow them to move out of
1021 // a synchronized region.
1022 while (current->is_Proj()) {
1023 int opc = current->in(0)->Opcode();
1024 if ((final && (opc == Op_MemBarAcquire ||
1025 opc == Op_MemBarAcquireLock ||
1026 opc == Op_LoadFence)) ||
1027 opc == Op_MemBarRelease ||
1028 opc == Op_StoreFence ||
1029 opc == Op_MemBarReleaseLock ||
1030 opc == Op_MemBarStoreStore ||
1031 opc == Op_MemBarCPUOrder) {
1032 Node* mem = current->in(0)->in(TypeFunc::Memory);
1033 if (mem->is_MergeMem()) {
1034 MergeMemNode* merge = mem->as_MergeMem();
1035 Node* new_st = merge->memory_at(alias_idx);
1036 if (new_st == merge->base_memory()) {
1037 // Keep searching
1038 current = new_st;
1039 continue;
1040 }
1041 // Save the new memory state for the slice and fall through
1042 // to exit.
1043 result = new_st;
1044 }
1045 }
1046 break;
1047 }
1048 if (result != NULL) {
1049 st = result;
1050 }
1051 }
1052
1053 // Loop around twice in the case Load -> Initialize -> Store.
1054 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1055 for (int trip = 0; trip <= 1; trip++) {
1056
1057 if (st->is_Store()) {
1058 Node* st_adr = st->in(MemNode::Address);
1059 if (!phase->eqv(st_adr, ld_adr)) {
1060 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1061 intptr_t st_off = 0;
1062 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1063 if (ld_base == NULL) return NULL;
1064 if (st_base == NULL) return NULL;
1065 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL;
1066 if (ld_off != st_off) return NULL;
1067 if (ld_off == Type::OffsetBot) return NULL;
1068 // Same base, same offset.
1069 // Possible improvement for arrays: check index value instead of absolute offset.
1070
1071 // At this point we have proven something like this setup:
1072 // B = << base >>
1073 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1074 // S = StoreQ(AddP( B , #Off), V)
1075 // (Actually, we haven't yet proven the Q's are the same.)
1076 // In other words, we are loading from a casted version of
1077 // the same pointer-and-offset that we stored to.
1078 // Casted version may carry a dependency and it is respected.
1079 // Thus, we are able to replace L by V.
1080 }
1081 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1082 if (store_Opcode() != st->Opcode())
1083 return NULL;
1084 return st->in(MemNode::ValueIn);
1085 }
1086
1087 // A load from a freshly-created object always returns zero.
1088 // (This can happen after LoadNode::Ideal resets the load's memory input
1089 // to find_captured_store, which returned InitializeNode::zero_memory.)
1090 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1091 (st->in(0) == ld_alloc) &&
1092 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1093 // return a zero value for the load's basic type
1094 // (This is one of the few places where a generic PhaseTransform
1095 // can create new nodes. Think of it as lazily manifesting
1096 // virtually pre-existing constants.)
1097 assert(memory_type() != T_VALUETYPE, "should not be used for value types");
1098 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1099 if (default_value != NULL) {
1100 return default_value;
1101 }
1102 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null");
1103 return phase->zerocon(memory_type());
1104 }
1105
1106 // A load from an initialization barrier can match a captured store.
1107 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1108 InitializeNode* init = st->in(0)->as_Initialize();
1109 AllocateNode* alloc = init->allocation();
1110 if ((alloc != NULL) && (alloc == ld_alloc)) {
1111 // examine a captured store value
1112 st = init->find_captured_store(ld_off, memory_size(), phase);
1113 if (st != NULL) {
1114 continue; // take one more trip around
1115 }
1116 }
1117 }
1118
1119 // Load boxed value from result of valueOf() call is input parameter.
1120 if (this->is_Load() && ld_adr->is_AddP() &&
1121 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1122 intptr_t ignore = 0;
1123 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1124 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1125 base = bs->step_over_gc_barrier(base);
1126 if (base != NULL && base->is_Proj() &&
1127 base->as_Proj()->_con == TypeFunc::Parms &&
1128 base->in(0)->is_CallStaticJava() &&
1129 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1130 return base->in(0)->in(TypeFunc::Parms);
1131 }
1132 }
1133
1134 break;
1135 }
1136
1137 return NULL;
1138 }
1139
1140 //----------------------is_instance_field_load_with_local_phi------------------
1141 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1142 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1143 in(Address)->is_AddP() ) {
1144 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1145 // Only instances and boxed values.
1146 if( t_oop != NULL &&
1147 (t_oop->is_ptr_to_boxed_value() ||
1148 t_oop->is_known_instance_field()) &&
1149 t_oop->offset() != Type::OffsetBot &&
1150 t_oop->offset() != Type::OffsetTop) {
1151 return true;
1152 }
1153 }
1154 return false;
1155 }
1156
1157 //------------------------------Identity---------------------------------------
1158 // Loads are identity if previous store is to same address
1159 Node* LoadNode::Identity(PhaseGVN* phase) {
1160 // Loading from a ValueTypePtr? The ValueTypePtr has the values of
1161 // all fields as input. Look for the field with matching offset.
1162 Node* addr = in(Address);
1163 intptr_t offset;
1164 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1165 if (base != NULL && base->is_ValueTypePtr() && offset > oopDesc::klass_offset_in_bytes()) {
1166 Node* value = base->as_ValueTypePtr()->field_value_by_offset((int)offset, true);
1167 if (value->is_ValueType()) {
1168 // Non-flattened value type field
1169 ValueTypeNode* vt = value->as_ValueType();
1170 if (vt->is_allocated(phase)) {
1171 value = vt->get_oop();
1172 } else {
1173 // Not yet allocated, bail out
1174 value = NULL;
1175 }
1176 }
1177 if (value != NULL) {
1178 if (Opcode() == Op_LoadN) {
1179 // Encode oop value if we are loading a narrow oop
1180 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1181 value = phase->transform(new EncodePNode(value, bottom_type()));
1182 }
1183 return value;
1184 }
1185 }
1186
1187 // If the previous store-maker is the right kind of Store, and the store is
1188 // to the same address, then we are equal to the value stored.
1189 Node* mem = in(Memory);
1190 Node* value = can_see_stored_value(mem, phase);
1191 if( value ) {
1192 // byte, short & char stores truncate naturally.
1193 // A load has to load the truncated value which requires
1194 // some sort of masking operation and that requires an
1195 // Ideal call instead of an Identity call.
1196 if (memory_size() < BytesPerInt) {
1197 // If the input to the store does not fit with the load's result type,
1198 // it must be truncated via an Ideal call.
1199 if (!phase->type(value)->higher_equal(phase->type(this)))
1200 return this;
1201 }
1202 // (This works even when value is a Con, but LoadNode::Value
1203 // usually runs first, producing the singleton type of the Con.)
1204 return value;
1205 }
1206
1207 // Search for an existing data phi which was generated before for the same
1208 // instance's field to avoid infinite generation of phis in a loop.
1209 Node *region = mem->in(0);
1210 if (is_instance_field_load_with_local_phi(region)) {
1211 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1212 int this_index = phase->C->get_alias_index(addr_t);
1213 int this_offset = addr_t->offset();
1214 int this_iid = addr_t->instance_id();
1215 if (!addr_t->is_known_instance() &&
1216 addr_t->is_ptr_to_boxed_value()) {
1217 // Use _idx of address base (could be Phi node) for boxed values.
1218 intptr_t ignore = 0;
1219 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1220 if (base == NULL) {
1221 return this;
1222 }
1223 this_iid = base->_idx;
1224 }
1225 const Type* this_type = bottom_type();
1226 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1227 Node* phi = region->fast_out(i);
1228 if (phi->is_Phi() && phi != mem &&
1229 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1230 return phi;
1231 }
1232 }
1233 }
1234
1235 return this;
1236 }
1237
1238 // Construct an equivalent unsigned load.
1239 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1240 BasicType bt = T_ILLEGAL;
1241 const Type* rt = NULL;
1242 switch (Opcode()) {
1243 case Op_LoadUB: return this;
1244 case Op_LoadUS: return this;
1245 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1246 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1247 default:
1248 assert(false, "no unsigned variant: %s", Name());
1249 return NULL;
1250 }
1251 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1252 raw_adr_type(), rt, bt, _mo, _control_dependency,
1253 is_unaligned_access(), is_mismatched_access());
1254 }
1255
1256 // Construct an equivalent signed load.
1257 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1258 BasicType bt = T_ILLEGAL;
1259 const Type* rt = NULL;
1260 switch (Opcode()) {
1261 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1262 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1263 case Op_LoadB: // fall through
1264 case Op_LoadS: // fall through
1265 case Op_LoadI: // fall through
1266 case Op_LoadL: return this;
1267 default:
1268 assert(false, "no signed variant: %s", Name());
1269 return NULL;
1270 }
1271 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1272 raw_adr_type(), rt, bt, _mo, _control_dependency,
1273 is_unaligned_access(), is_mismatched_access());
1274 }
1275
1276 // We're loading from an object which has autobox behaviour.
1277 // If this object is result of a valueOf call we'll have a phi
1278 // merging a newly allocated object and a load from the cache.
1279 // We want to replace this load with the original incoming
1280 // argument to the valueOf call.
1281 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1282 assert(phase->C->eliminate_boxing(), "sanity");
1283 intptr_t ignore = 0;
1284 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1285 if ((base == NULL) || base->is_Phi()) {
1286 // Push the loads from the phi that comes from valueOf up
1287 // through it to allow elimination of the loads and the recovery
1288 // of the original value. It is done in split_through_phi().
1289 return NULL;
1290 } else if (base->is_Load() ||
1291 (base->is_DecodeN() && base->in(1)->is_Load())) {
1292 // Eliminate the load of boxed value for integer types from the cache
1293 // array by deriving the value from the index into the array.
1294 // Capture the offset of the load and then reverse the computation.
1295
1296 // Get LoadN node which loads a boxing object from 'cache' array.
1297 if (base->is_DecodeN()) {
1298 base = base->in(1);
1299 }
1300 if (!base->in(Address)->is_AddP()) {
1301 return NULL; // Complex address
1302 }
1303 AddPNode* address = base->in(Address)->as_AddP();
1304 Node* cache_base = address->in(AddPNode::Base);
1305 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1306 // Get ConP node which is static 'cache' field.
1307 cache_base = cache_base->in(1);
1308 }
1309 if ((cache_base != NULL) && cache_base->is_Con()) {
1310 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1311 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1312 Node* elements[4];
1313 int shift = exact_log2(type2aelembytes(T_OBJECT));
1314 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1315 if (count > 0 && elements[0]->is_Con() &&
1316 (count == 1 ||
1317 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1318 elements[1]->in(2) == phase->intcon(shift)))) {
1319 ciObjArray* array = base_type->const_oop()->as_obj_array();
1320 // Fetch the box object cache[0] at the base of the array and get its value
1321 ciInstance* box = array->obj_at(0)->as_instance();
1322 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1323 assert(ik->is_box_klass(), "sanity");
1324 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1325 if (ik->nof_nonstatic_fields() == 1) {
1326 // This should be true nonstatic_field_at requires calling
1327 // nof_nonstatic_fields so check it anyway
1328 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1329 BasicType bt = c.basic_type();
1330 // Only integer types have boxing cache.
1331 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1332 bt == T_BYTE || bt == T_SHORT ||
1333 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1334 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1335 if (cache_low != (int)cache_low) {
1336 return NULL; // should not happen since cache is array indexed by value
1337 }
1338 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1339 if (offset != (int)offset) {
1340 return NULL; // should not happen since cache is array indexed by value
1341 }
1342 // Add up all the offsets making of the address of the load
1343 Node* result = elements[0];
1344 for (int i = 1; i < count; i++) {
1345 result = phase->transform(new AddXNode(result, elements[i]));
1346 }
1347 // Remove the constant offset from the address and then
1348 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1349 // remove the scaling of the offset to recover the original index.
1350 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1351 // Peel the shift off directly but wrap it in a dummy node
1352 // since Ideal can't return existing nodes
1353 result = new RShiftXNode(result->in(1), phase->intcon(0));
1354 } else if (result->is_Add() && result->in(2)->is_Con() &&
1355 result->in(1)->Opcode() == Op_LShiftX &&
1356 result->in(1)->in(2) == phase->intcon(shift)) {
1357 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1358 // but for boxing cache access we know that X<<Z will not overflow
1359 // (there is range check) so we do this optimizatrion by hand here.
1360 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1361 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1362 } else {
1363 result = new RShiftXNode(result, phase->intcon(shift));
1364 }
1365 #ifdef _LP64
1366 if (bt != T_LONG) {
1367 result = new ConvL2INode(phase->transform(result));
1368 }
1369 #else
1370 if (bt == T_LONG) {
1371 result = new ConvI2LNode(phase->transform(result));
1372 }
1373 #endif
1374 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1375 // Need to preserve unboxing load type if it is unsigned.
1376 switch(this->Opcode()) {
1377 case Op_LoadUB:
1378 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1379 break;
1380 case Op_LoadUS:
1381 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1382 break;
1383 }
1384 return result;
1385 }
1386 }
1387 }
1388 }
1389 }
1390 return NULL;
1391 }
1392
1393 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1394 Node* region = phi->in(0);
1395 if (region == NULL) {
1396 return false; // Wait stable graph
1397 }
1398 uint cnt = phi->req();
1399 for (uint i = 1; i < cnt; i++) {
1400 Node* rc = region->in(i);
1401 if (rc == NULL || phase->type(rc) == Type::TOP)
1402 return false; // Wait stable graph
1403 Node* in = phi->in(i);
1404 if (in == NULL || phase->type(in) == Type::TOP)
1405 return false; // Wait stable graph
1406 }
1407 return true;
1408 }
1409 //------------------------------split_through_phi------------------------------
1410 // Split instance or boxed field load through Phi.
1411 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1412 Node* mem = in(Memory);
1413 Node* address = in(Address);
1414 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1415
1416 assert((t_oop != NULL) &&
1417 (t_oop->is_known_instance_field() ||
1418 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1419
1420 Compile* C = phase->C;
1421 intptr_t ignore = 0;
1422 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1423 bool base_is_phi = (base != NULL) && base->is_Phi();
1424 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1425 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1426 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1427
1428 if (!((mem->is_Phi() || base_is_phi) &&
1429 (load_boxed_values || t_oop->is_known_instance_field()))) {
1430 return NULL; // memory is not Phi
1431 }
1432
1433 if (mem->is_Phi()) {
1434 if (!stable_phi(mem->as_Phi(), phase)) {
1435 return NULL; // Wait stable graph
1436 }
1437 uint cnt = mem->req();
1438 // Check for loop invariant memory.
1439 if (cnt == 3) {
1440 for (uint i = 1; i < cnt; i++) {
1441 Node* in = mem->in(i);
1442 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1443 if (m == mem) {
1444 if (i == 1) {
1445 // if the first edge was a loop, check second edge too.
1446 // If both are replaceable - we are in an infinite loop
1447 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1448 if (n == mem) {
1449 break;
1450 }
1451 }
1452 set_req(Memory, mem->in(cnt - i));
1453 return this; // made change
1454 }
1455 }
1456 }
1457 }
1458 if (base_is_phi) {
1459 if (!stable_phi(base->as_Phi(), phase)) {
1460 return NULL; // Wait stable graph
1461 }
1462 uint cnt = base->req();
1463 // Check for loop invariant memory.
1464 if (cnt == 3) {
1465 for (uint i = 1; i < cnt; i++) {
1466 if (base->in(i) == base) {
1467 return NULL; // Wait stable graph
1468 }
1469 }
1470 }
1471 }
1472
1473 // Split through Phi (see original code in loopopts.cpp).
1474 assert(C->have_alias_type(t_oop), "instance should have alias type");
1475
1476 // Do nothing here if Identity will find a value
1477 // (to avoid infinite chain of value phis generation).
1478 if (!phase->eqv(this, phase->apply_identity(this)))
1479 return NULL;
1480
1481 // Select Region to split through.
1482 Node* region;
1483 if (!base_is_phi) {
1484 assert(mem->is_Phi(), "sanity");
1485 region = mem->in(0);
1486 // Skip if the region dominates some control edge of the address.
1487 if (!MemNode::all_controls_dominate(address, region))
1488 return NULL;
1489 } else if (!mem->is_Phi()) {
1490 assert(base_is_phi, "sanity");
1491 region = base->in(0);
1492 // Skip if the region dominates some control edge of the memory.
1493 if (!MemNode::all_controls_dominate(mem, region))
1494 return NULL;
1495 } else if (base->in(0) != mem->in(0)) {
1496 assert(base_is_phi && mem->is_Phi(), "sanity");
1497 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1498 region = base->in(0);
1499 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1500 region = mem->in(0);
1501 } else {
1502 return NULL; // complex graph
1503 }
1504 } else {
1505 assert(base->in(0) == mem->in(0), "sanity");
1506 region = mem->in(0);
1507 }
1508
1509 const Type* this_type = this->bottom_type();
1510 int this_index = C->get_alias_index(t_oop);
1511 int this_offset = t_oop->offset();
1512 int this_iid = t_oop->instance_id();
1513 if (!t_oop->is_known_instance() && load_boxed_values) {
1514 // Use _idx of address base for boxed values.
1515 this_iid = base->_idx;
1516 }
1517 PhaseIterGVN* igvn = phase->is_IterGVN();
1518 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1519 for (uint i = 1; i < region->req(); i++) {
1520 Node* x;
1521 Node* the_clone = NULL;
1522 if (region->in(i) == C->top()) {
1523 x = C->top(); // Dead path? Use a dead data op
1524 } else {
1525 x = this->clone(); // Else clone up the data op
1526 the_clone = x; // Remember for possible deletion.
1527 // Alter data node to use pre-phi inputs
1528 if (this->in(0) == region) {
1529 x->set_req(0, region->in(i));
1530 } else {
1531 x->set_req(0, NULL);
1532 }
1533 if (mem->is_Phi() && (mem->in(0) == region)) {
1534 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1535 }
1536 if (address->is_Phi() && address->in(0) == region) {
1537 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1538 }
1539 if (base_is_phi && (base->in(0) == region)) {
1540 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1541 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1542 x->set_req(Address, adr_x);
1543 }
1544 }
1545 // Check for a 'win' on some paths
1546 const Type *t = x->Value(igvn);
1547
1548 bool singleton = t->singleton();
1549
1550 // See comments in PhaseIdealLoop::split_thru_phi().
1551 if (singleton && t == Type::TOP) {
1552 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1553 }
1554
1555 if (singleton) {
1556 x = igvn->makecon(t);
1557 } else {
1558 // We now call Identity to try to simplify the cloned node.
1559 // Note that some Identity methods call phase->type(this).
1560 // Make sure that the type array is big enough for
1561 // our new node, even though we may throw the node away.
1562 // (This tweaking with igvn only works because x is a new node.)
1563 igvn->set_type(x, t);
1564 // If x is a TypeNode, capture any more-precise type permanently into Node
1565 // otherwise it will be not updated during igvn->transform since
1566 // igvn->type(x) is set to x->Value() already.
1567 x->raise_bottom_type(t);
1568 Node *y = igvn->apply_identity(x);
1569 if (y != x) {
1570 x = y;
1571 } else {
1572 y = igvn->hash_find_insert(x);
1573 if (y) {
1574 x = y;
1575 } else {
1576 // Else x is a new node we are keeping
1577 // We do not need register_new_node_with_optimizer
1578 // because set_type has already been called.
1579 igvn->_worklist.push(x);
1580 }
1581 }
1582 }
1583 if (x != the_clone && the_clone != NULL) {
1584 igvn->remove_dead_node(the_clone);
1585 }
1586 phi->set_req(i, x);
1587 }
1588 // Record Phi
1589 igvn->register_new_node_with_optimizer(phi);
1590 return phi;
1591 }
1592
1593 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1594 if (Opcode() == Op_LoadX) {
1595 Node* address = in(MemNode::Address);
1596 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1597 Node* mem = in(MemNode::Memory);
1598 if (alloc != NULL && mem->is_Proj() &&
1599 mem->in(0) != NULL &&
1600 mem->in(0) == alloc->initialization() &&
1601 alloc->initialization()->proj_out_or_null(0) != NULL) {
1602 return alloc;
1603 }
1604 }
1605 return NULL;
1606 }
1607
1608
1609 //------------------------------Ideal------------------------------------------
1610 // If the load is from Field memory and the pointer is non-null, it might be possible to
1611 // zero out the control input.
1612 // If the offset is constant and the base is an object allocation,
1613 // try to hook me up to the exact initializing store.
1614 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1615 Node* p = MemNode::Ideal_common(phase, can_reshape);
1616 if (p) return (p == NodeSentinel) ? NULL : p;
1617
1618 Node* ctrl = in(MemNode::Control);
1619 Node* address = in(MemNode::Address);
1620 bool progress = false;
1621
1622 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1623 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1624
1625 // Skip up past a SafePoint control. Cannot do this for Stores because
1626 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1627 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1628 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1629 !addr_mark &&
1630 (depends_only_on_test() || has_unknown_control_dependency())) {
1631 ctrl = ctrl->in(0);
1632 set_req(MemNode::Control,ctrl);
1633 progress = true;
1634 }
1635
1636 intptr_t ignore = 0;
1637 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1638 if (base != NULL
1639 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1640 // Check for useless control edge in some common special cases
1641 if (in(MemNode::Control) != NULL
1642 && can_remove_control()
1643 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1644 && all_controls_dominate(base, phase->C->start())) {
1645 // A method-invariant, non-null address (constant or 'this' argument).
1646 set_req(MemNode::Control, NULL);
1647 progress = true;
1648 }
1649 }
1650
1651 Node* mem = in(MemNode::Memory);
1652 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1653
1654 if (can_reshape && (addr_t != NULL)) {
1655 // try to optimize our memory input
1656 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1657 if (opt_mem != mem) {
1658 set_req(MemNode::Memory, opt_mem);
1659 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1660 return this;
1661 }
1662 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1663 if ((t_oop != NULL) &&
1664 (t_oop->is_known_instance_field() ||
1665 t_oop->is_ptr_to_boxed_value())) {
1666 PhaseIterGVN *igvn = phase->is_IterGVN();
1667 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1668 // Delay this transformation until memory Phi is processed.
1669 phase->is_IterGVN()->_worklist.push(this);
1670 return NULL;
1671 }
1672 // Split instance field load through Phi.
1673 Node* result = split_through_phi(phase);
1674 if (result != NULL) return result;
1675
1676 if (t_oop->is_ptr_to_boxed_value()) {
1677 Node* result = eliminate_autobox(phase);
1678 if (result != NULL) return result;
1679 }
1680 }
1681 }
1682
1683 // Is there a dominating load that loads the same value? Leave
1684 // anything that is not a load of a field/array element (like
1685 // barriers etc.) alone
1686 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1687 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1688 Node *use = mem->fast_out(i);
1689 if (use != this &&
1690 use->Opcode() == Opcode() &&
1691 use->in(0) != NULL &&
1692 use->in(0) != in(0) &&
1693 use->in(Address) == in(Address)) {
1694 Node* ctl = in(0);
1695 for (int i = 0; i < 10 && ctl != NULL; i++) {
1696 ctl = IfNode::up_one_dom(ctl);
1697 if (ctl == use->in(0)) {
1698 set_req(0, use->in(0));
1699 return this;
1700 }
1701 }
1702 }
1703 }
1704 }
1705
1706 // Check for prior store with a different base or offset; make Load
1707 // independent. Skip through any number of them. Bail out if the stores
1708 // are in an endless dead cycle and report no progress. This is a key
1709 // transform for Reflection. However, if after skipping through the Stores
1710 // we can't then fold up against a prior store do NOT do the transform as
1711 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1712 // array memory alive twice: once for the hoisted Load and again after the
1713 // bypassed Store. This situation only works if EVERYBODY who does
1714 // anti-dependence work knows how to bypass. I.e. we need all
1715 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1716 // the alias index stuff. So instead, peek through Stores and IFF we can
1717 // fold up, do so.
1718 Node* prev_mem = find_previous_store(phase);
1719 if (prev_mem != NULL) {
1720 Node* value = can_see_arraycopy_value(prev_mem, phase);
1721 if (value != NULL) {
1722 return value;
1723 }
1724 }
1725 // Steps (a), (b): Walk past independent stores to find an exact match.
1726 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1727 // (c) See if we can fold up on the spot, but don't fold up here.
1728 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1729 // just return a prior value, which is done by Identity calls.
1730 if (can_see_stored_value(prev_mem, phase)) {
1731 // Make ready for step (d):
1732 set_req(MemNode::Memory, prev_mem);
1733 return this;
1734 }
1735 }
1736
1737 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1738 if (alloc != NULL && mem->is_Proj() &&
1739 mem->in(0) != NULL &&
1740 mem->in(0) == alloc->initialization() &&
1741 Opcode() == Op_LoadX &&
1742 alloc->initialization()->proj_out_or_null(0) != NULL) {
1743 InitializeNode* init = alloc->initialization();
1744 Node* control = init->proj_out(0);
1745 return alloc->make_ideal_mark(phase, address, control, mem);
1746 }
1747
1748 return progress ? this : NULL;
1749 }
1750
1751 // Helper to recognize certain Klass fields which are invariant across
1752 // some group of array types (e.g., int[] or all T[] where T < Object).
1753 const Type*
1754 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1755 ciKlass* klass) const {
1756 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1757 // The field is Klass::_modifier_flags. Return its (constant) value.
1758 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1759 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1760 return TypeInt::make(klass->modifier_flags());
1761 }
1762 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1763 // The field is Klass::_access_flags. Return its (constant) value.
1764 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1765 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1766 return TypeInt::make(klass->access_flags());
1767 }
1768 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1769 // The field is Klass::_layout_helper. Return its constant value if known.
1770 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1771 return TypeInt::make(klass->layout_helper());
1772 }
1773
1774 // No match.
1775 return NULL;
1776 }
1777
1778 //------------------------------Value-----------------------------------------
1779 const Type* LoadNode::Value(PhaseGVN* phase) const {
1780 // Either input is TOP ==> the result is TOP
1781 Node* mem = in(MemNode::Memory);
1782 const Type *t1 = phase->type(mem);
1783 if (t1 == Type::TOP) return Type::TOP;
1784 Node* adr = in(MemNode::Address);
1785 const TypePtr* tp = phase->type(adr)->isa_ptr();
1786 if (tp == NULL || tp->empty()) return Type::TOP;
1787 int off = tp->offset();
1788 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1789 Compile* C = phase->C;
1790
1791 // Try to guess loaded type from pointer type
1792 if (tp->isa_aryptr()) {
1793 const TypeAryPtr* ary = tp->is_aryptr();
1794 const Type* t = ary->elem();
1795
1796 // Determine whether the reference is beyond the header or not, by comparing
1797 // the offset against the offset of the start of the array's data.
1798 // Different array types begin at slightly different offsets (12 vs. 16).
1799 // We choose T_BYTE as an example base type that is least restrictive
1800 // as to alignment, which will therefore produce the smallest
1801 // possible base offset.
1802 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1803 const bool off_beyond_header = (off >= min_base_off);
1804
1805 // Try to constant-fold a stable array element.
1806 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1807 // Make sure the reference is not into the header and the offset is constant
1808 ciObject* aobj = ary->const_oop();
1809 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1810 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1811 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1812 stable_dimension,
1813 memory_type(), is_unsigned());
1814 if (con_type != NULL) {
1815 return con_type;
1816 }
1817 }
1818 }
1819
1820 // Don't do this for integer types. There is only potential profit if
1821 // the element type t is lower than _type; that is, for int types, if _type is
1822 // more restrictive than t. This only happens here if one is short and the other
1823 // char (both 16 bits), and in those cases we've made an intentional decision
1824 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1825 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1826 //
1827 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1828 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1829 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1830 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1831 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1832 // In fact, that could have been the original type of p1, and p1 could have
1833 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1834 // expression (LShiftL quux 3) independently optimized to the constant 8.
1835 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1836 && (_type->isa_vect() == NULL)
1837 && t->isa_valuetype() == NULL
1838 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1839 // t might actually be lower than _type, if _type is a unique
1840 // concrete subclass of abstract class t.
1841 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1842 const Type* jt = t->join_speculative(_type);
1843 // In any case, do not allow the join, per se, to empty out the type.
1844 if (jt->empty() && !t->empty()) {
1845 // This can happen if a interface-typed array narrows to a class type.
1846 jt = _type;
1847 }
1848 #ifdef ASSERT
1849 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1850 // The pointers in the autobox arrays are always non-null
1851 Node* base = adr->in(AddPNode::Base);
1852 if ((base != NULL) && base->is_DecodeN()) {
1853 // Get LoadN node which loads IntegerCache.cache field
1854 base = base->in(1);
1855 }
1856 if ((base != NULL) && base->is_Con()) {
1857 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1858 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1859 // It could be narrow oop
1860 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1861 }
1862 }
1863 }
1864 #endif
1865 return jt;
1866 }
1867 }
1868 } else if (tp->base() == Type::InstPtr) {
1869 assert( off != Type::OffsetBot ||
1870 // arrays can be cast to Objects
1871 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1872 tp->is_oopptr()->klass() == ciEnv::current()->Class_klass() ||
1873 // unsafe field access may not have a constant offset
1874 C->has_unsafe_access(),
1875 "Field accesses must be precise" );
1876 // For oop loads, we expect the _type to be precise.
1877
1878 const TypeInstPtr* tinst = tp->is_instptr();
1879 BasicType bt = memory_type();
1880
1881 // Fold component and value mirror loads
1882 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1883 if (ik == phase->C->env()->Class_klass() && (off == java_lang_Class::component_mirror_offset_in_bytes() ||
1884 off == java_lang_Class::inline_mirror_offset_in_bytes())) {
1885 ciType* mirror_type = tinst->java_mirror_type();
1886 if (mirror_type != NULL) {
1887 const Type* const_oop = TypePtr::NULL_PTR;
1888 if (mirror_type->is_array_klass()) {
1889 const_oop = TypeInstPtr::make(mirror_type->as_array_klass()->component_mirror_instance());
1890 } else if (mirror_type->is_valuetype()) {
1891 const_oop = TypeInstPtr::make(mirror_type->as_value_klass()->inline_mirror_instance());
1892 }
1893 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
1894 }
1895 }
1896
1897 // Optimize loads from constant fields.
1898 ciObject* const_oop = tinst->const_oop();
1899 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1900 ciType* mirror_type = const_oop->as_instance()->java_mirror_type();
1901 if (mirror_type != NULL && mirror_type->is_valuetype()) {
1902 ciValueKlass* vk = mirror_type->as_value_klass();
1903 if (off == vk->default_value_offset()) {
1904 // Loading a special hidden field that contains the oop of the default value type
1905 const Type* const_oop = TypeInstPtr::make(vk->default_value_instance());
1906 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
1907 }
1908 }
1909 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
1910 if (con_type != NULL) {
1911 return con_type;
1912 }
1913 }
1914 } else if (tp->base() == Type::KlassPtr) {
1915 assert( off != Type::OffsetBot ||
1916 // arrays can be cast to Objects
1917 tp->is_klassptr()->klass() == NULL ||
1918 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1919 // also allow array-loading from the primary supertype
1920 // array during subtype checks
1921 Opcode() == Op_LoadKlass,
1922 "Field accesses must be precise" );
1923 // For klass/static loads, we expect the _type to be precise
1924 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
1925 if (adr->is_Load() && off == 0) {
1926 /* With mirrors being an indirect in the Klass*
1927 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1928 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1929 *
1930 * So check the type and klass of the node before the LoadP.
1931 */
1932 Node* adr2 = adr->in(MemNode::Address);
1933 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1934 if (tkls != NULL) {
1935 ciKlass* klass = tkls->klass();
1936 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1937 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1938 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1939 return TypeInstPtr::make(klass->java_mirror());
1940 }
1941 }
1942 } else {
1943 // Check for a load of the default value offset from the ValueKlassFixedBlock:
1944 // LoadI(LoadP(value_klass, adr_valueklass_fixed_block_offset), default_value_offset_offset)
1945 intptr_t offset = 0;
1946 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1947 if (base != NULL && base->is_Load() && offset == in_bytes(ValueKlass::default_value_offset_offset())) {
1948 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
1949 if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->isa_valuetype() &&
1950 tkls->offset() == in_bytes(InstanceKlass::adr_valueklass_fixed_block_offset())) {
1951 assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
1952 assert(Opcode() == Op_LoadI, "must load an int from fixed block");
1953 return TypeInt::make(tkls->klass()->as_value_klass()->default_value_offset());
1954 }
1955 }
1956 }
1957 }
1958
1959 const TypeKlassPtr *tkls = tp->isa_klassptr();
1960 if (tkls != NULL && !StressReflectiveCode) {
1961 ciKlass* klass = tkls->klass();
1962 if (tkls->is_loaded() && tkls->klass_is_exact()) {
1963 // We are loading a field from a Klass metaobject whose identity
1964 // is known at compile time (the type is "exact" or "precise").
1965 // Check for fields we know are maintained as constants by the VM.
1966 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1967 // The field is Klass::_super_check_offset. Return its (constant) value.
1968 // (Folds up type checking code.)
1969 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1970 return TypeInt::make(klass->super_check_offset());
1971 }
1972 // Compute index into primary_supers array
1973 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1974 // Check for overflowing; use unsigned compare to handle the negative case.
1975 if( depth < ciKlass::primary_super_limit() ) {
1976 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1977 // (Folds up type checking code.)
1978 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1979 ciKlass *ss = klass->super_of_depth(depth);
1980 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1981 }
1982 const Type* aift = load_array_final_field(tkls, klass);
1983 if (aift != NULL) return aift;
1984 }
1985
1986 // We can still check if we are loading from the primary_supers array at a
1987 // shallow enough depth. Even though the klass is not exact, entries less
1988 // than or equal to its super depth are correct.
1989 if (tkls->is_loaded()) {
1990 ciType *inner = klass;
1991 while( inner->is_obj_array_klass() )
1992 inner = inner->as_obj_array_klass()->base_element_type();
1993 if( inner->is_instance_klass() &&
1994 !inner->as_instance_klass()->flags().is_interface() ) {
1995 // Compute index into primary_supers array
1996 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1997 // Check for overflowing; use unsigned compare to handle the negative case.
1998 if( depth < ciKlass::primary_super_limit() &&
1999 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
2000 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2001 // (Folds up type checking code.)
2002 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2003 ciKlass *ss = klass->super_of_depth(depth);
2004 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2005 }
2006 }
2007 }
2008
2009 // If the type is enough to determine that the thing is not an array,
2010 // we can give the layout_helper a positive interval type.
2011 // This will help short-circuit some reflective code.
2012 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
2013 && !klass->is_array_klass() // not directly typed as an array
2014 && !klass->is_interface() // specifically not Serializable & Cloneable
2015 && !klass->is_java_lang_Object() // not the supertype of all T[]
2016 ) {
2017 // Note: When interfaces are reliable, we can narrow the interface
2018 // test to (klass != Serializable && klass != Cloneable).
2019 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2020 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2021 // The key property of this type is that it folds up tests
2022 // for array-ness, since it proves that the layout_helper is positive.
2023 // Thus, a generic value like the basic object layout helper works fine.
2024 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2025 }
2026 }
2027
2028 // If we are loading from a freshly-allocated object, produce a zero,
2029 // if the load is provably beyond the header of the object.
2030 // (Also allow a variable load from a fresh array to produce zero.)
2031 const TypeOopPtr *tinst = tp->isa_oopptr();
2032 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
2033 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
2034 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2035 Node* value = can_see_stored_value(mem,phase);
2036 if (value != NULL && value->is_Con()) {
2037 assert(value->bottom_type()->higher_equal(_type),"sanity");
2038 return value->bottom_type();
2039 }
2040 }
2041
2042 if (is_instance) {
2043 // If we have an instance type and our memory input is the
2044 // programs's initial memory state, there is no matching store,
2045 // so just return a zero of the appropriate type
2046 Node *mem = in(MemNode::Memory);
2047 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2048 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2049 return Type::get_zero_type(_type->basic_type());
2050 }
2051 }
2052
2053 Node* alloc = is_new_object_mark_load(phase);
2054 if (alloc != NULL && !(alloc->Opcode() == Op_Allocate && UseBiasedLocking)) {
2055 return TypeX::make(markWord::prototype().value());
2056 }
2057
2058 return _type;
2059 }
2060
2061 //------------------------------match_edge-------------------------------------
2062 // Do we Match on this edge index or not? Match only the address.
2063 uint LoadNode::match_edge(uint idx) const {
2064 return idx == MemNode::Address;
2065 }
2066
2067 //--------------------------LoadBNode::Ideal--------------------------------------
2068 //
2069 // If the previous store is to the same address as this load,
2070 // and the value stored was larger than a byte, replace this load
2071 // with the value stored truncated to a byte. If no truncation is
2072 // needed, the replacement is done in LoadNode::Identity().
2073 //
2074 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2075 Node* mem = in(MemNode::Memory);
2076 Node* value = can_see_stored_value(mem,phase);
2077 if( value && !phase->type(value)->higher_equal( _type ) ) {
2078 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
2079 return new RShiftINode(result, phase->intcon(24));
2080 }
2081 // Identity call will handle the case where truncation is not needed.
2082 return LoadNode::Ideal(phase, can_reshape);
2083 }
2084
2085 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2086 Node* mem = in(MemNode::Memory);
2087 Node* value = can_see_stored_value(mem,phase);
2088 if (value != NULL && value->is_Con() &&
2089 !value->bottom_type()->higher_equal(_type)) {
2090 // If the input to the store does not fit with the load's result type,
2091 // it must be truncated. We can't delay until Ideal call since
2092 // a singleton Value is needed for split_thru_phi optimization.
2093 int con = value->get_int();
2094 return TypeInt::make((con << 24) >> 24);
2095 }
2096 return LoadNode::Value(phase);
2097 }
2098
2099 //--------------------------LoadUBNode::Ideal-------------------------------------
2100 //
2101 // If the previous store is to the same address as this load,
2102 // and the value stored was larger than a byte, replace this load
2103 // with the value stored truncated to a byte. If no truncation is
2104 // needed, the replacement is done in LoadNode::Identity().
2105 //
2106 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2107 Node* mem = in(MemNode::Memory);
2108 Node* value = can_see_stored_value(mem, phase);
2109 if (value && !phase->type(value)->higher_equal(_type))
2110 return new AndINode(value, phase->intcon(0xFF));
2111 // Identity call will handle the case where truncation is not needed.
2112 return LoadNode::Ideal(phase, can_reshape);
2113 }
2114
2115 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2116 Node* mem = in(MemNode::Memory);
2117 Node* value = can_see_stored_value(mem,phase);
2118 if (value != NULL && value->is_Con() &&
2119 !value->bottom_type()->higher_equal(_type)) {
2120 // If the input to the store does not fit with the load's result type,
2121 // it must be truncated. We can't delay until Ideal call since
2122 // a singleton Value is needed for split_thru_phi optimization.
2123 int con = value->get_int();
2124 return TypeInt::make(con & 0xFF);
2125 }
2126 return LoadNode::Value(phase);
2127 }
2128
2129 //--------------------------LoadUSNode::Ideal-------------------------------------
2130 //
2131 // If the previous store is to the same address as this load,
2132 // and the value stored was larger than a char, replace this load
2133 // with the value stored truncated to a char. If no truncation is
2134 // needed, the replacement is done in LoadNode::Identity().
2135 //
2136 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2137 Node* mem = in(MemNode::Memory);
2138 Node* value = can_see_stored_value(mem,phase);
2139 if( value && !phase->type(value)->higher_equal( _type ) )
2140 return new AndINode(value,phase->intcon(0xFFFF));
2141 // Identity call will handle the case where truncation is not needed.
2142 return LoadNode::Ideal(phase, can_reshape);
2143 }
2144
2145 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2146 Node* mem = in(MemNode::Memory);
2147 Node* value = can_see_stored_value(mem,phase);
2148 if (value != NULL && value->is_Con() &&
2149 !value->bottom_type()->higher_equal(_type)) {
2150 // If the input to the store does not fit with the load's result type,
2151 // it must be truncated. We can't delay until Ideal call since
2152 // a singleton Value is needed for split_thru_phi optimization.
2153 int con = value->get_int();
2154 return TypeInt::make(con & 0xFFFF);
2155 }
2156 return LoadNode::Value(phase);
2157 }
2158
2159 //--------------------------LoadSNode::Ideal--------------------------------------
2160 //
2161 // If the previous store is to the same address as this load,
2162 // and the value stored was larger than a short, replace this load
2163 // with the value stored truncated to a short. If no truncation is
2164 // needed, the replacement is done in LoadNode::Identity().
2165 //
2166 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2167 Node* mem = in(MemNode::Memory);
2168 Node* value = can_see_stored_value(mem,phase);
2169 if( value && !phase->type(value)->higher_equal( _type ) ) {
2170 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2171 return new RShiftINode(result, phase->intcon(16));
2172 }
2173 // Identity call will handle the case where truncation is not needed.
2174 return LoadNode::Ideal(phase, can_reshape);
2175 }
2176
2177 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2178 Node* mem = in(MemNode::Memory);
2179 Node* value = can_see_stored_value(mem,phase);
2180 if (value != NULL && value->is_Con() &&
2181 !value->bottom_type()->higher_equal(_type)) {
2182 // If the input to the store does not fit with the load's result type,
2183 // it must be truncated. We can't delay until Ideal call since
2184 // a singleton Value is needed for split_thru_phi optimization.
2185 int con = value->get_int();
2186 return TypeInt::make((con << 16) >> 16);
2187 }
2188 return LoadNode::Value(phase);
2189 }
2190
2191 //=============================================================================
2192 //----------------------------LoadKlassNode::make------------------------------
2193 // Polymorphic factory method:
2194 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2195 // sanity check the alias category against the created node type
2196 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2197 assert(adr_type != NULL, "expecting TypeKlassPtr");
2198 #ifdef _LP64
2199 if (adr_type->is_ptr_to_narrowklass()) {
2200 assert(UseCompressedClassPointers, "no compressed klasses");
2201 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2202 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2203 }
2204 #endif
2205 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2206 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2207 }
2208
2209 //------------------------------Value------------------------------------------
2210 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2211 return klass_value_common(phase);
2212 }
2213
2214 // In most cases, LoadKlassNode does not have the control input set. If the control
2215 // input is set, it must not be removed (by LoadNode::Ideal()).
2216 bool LoadKlassNode::can_remove_control() const {
2217 return false;
2218 }
2219
2220 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2221 // Either input is TOP ==> the result is TOP
2222 const Type *t1 = phase->type( in(MemNode::Memory) );
2223 if (t1 == Type::TOP) return Type::TOP;
2224 Node *adr = in(MemNode::Address);
2225 const Type *t2 = phase->type( adr );
2226 if (t2 == Type::TOP) return Type::TOP;
2227 const TypePtr *tp = t2->is_ptr();
2228 if (TypePtr::above_centerline(tp->ptr()) ||
2229 tp->ptr() == TypePtr::Null) return Type::TOP;
2230
2231 // Return a more precise klass, if possible
2232 const TypeInstPtr *tinst = tp->isa_instptr();
2233 if (tinst != NULL) {
2234 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2235 int offset = tinst->offset();
2236 if (ik == phase->C->env()->Class_klass()
2237 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2238 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2239 // We are loading a special hidden field from a Class mirror object,
2240 // the field which points to the VM's Klass metaobject.
2241 bool is_indirect_type = true;
2242 ciType* t = tinst->java_mirror_type(&is_indirect_type);
2243 // java_mirror_type returns non-null for compile-time Class constants.
2244 if (t != NULL) {
2245 // constant oop => constant klass
2246 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2247 if (t->is_void()) {
2248 // We cannot create a void array. Since void is a primitive type return null
2249 // klass. Users of this result need to do a null check on the returned klass.
2250 return TypePtr::NULL_PTR;
2251 }
2252 return TypeKlassPtr::make(ciArrayKlass::make(t, /* never_null */ !is_indirect_type));
2253 }
2254 if (!t->is_klass()) {
2255 // a primitive Class (e.g., int.class) has NULL for a klass field
2256 return TypePtr::NULL_PTR;
2257 }
2258 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2259 return TypeKlassPtr::make(t->as_klass());
2260 }
2261 // non-constant mirror, so we can't tell what's going on
2262 }
2263 if( !ik->is_loaded() )
2264 return _type; // Bail out if not loaded
2265 if (offset == oopDesc::klass_offset_in_bytes()) {
2266 if (tinst->klass_is_exact()) {
2267 return TypeKlassPtr::make(ik);
2268 }
2269 // See if we can become precise: no subklasses and no interface
2270 // (Note: We need to support verified interfaces.)
2271 if (!ik->is_interface() && !ik->has_subklass()) {
2272 //assert(!UseExactTypes, "this code should be useless with exact types");
2273 // Add a dependence; if any subclass added we need to recompile
2274 if (!ik->is_final()) {
2275 // %%% should use stronger assert_unique_concrete_subtype instead
2276 phase->C->dependencies()->assert_leaf_type(ik);
2277 }
2278 // Return precise klass
2279 return TypeKlassPtr::make(ik);
2280 }
2281
2282 // Return root of possible klass
2283 return TypeKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0), tinst->flat_array());
2284 }
2285 }
2286
2287 // Check for loading klass from an array
2288 const TypeAryPtr *tary = tp->isa_aryptr();
2289 if (tary != NULL) {
2290 ciKlass *tary_klass = tary->klass();
2291 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2292 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2293 ciArrayKlass* ak = tary_klass->as_array_klass();
2294 // Do not fold klass loads from [V?. The runtime type might be [V due to [V <: [V?
2295 // and the klass for [V is not equal to the klass for [V?.
2296 if (tary->klass_is_exact()) {
2297 return TypeKlassPtr::make(tary_klass);
2298 }
2299
2300 // If the klass is an object array, we defer the question to the
2301 // array component klass.
2302 if (ak->is_obj_array_klass()) {
2303 assert(ak->is_loaded(), "");
2304 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2305 if (base_k->is_loaded() && base_k->is_instance_klass()) {
2306 ciInstanceKlass *ik = base_k->as_instance_klass();
2307 // See if we can become precise: no subklasses and no interface
2308 if (!ik->is_interface() && !ik->has_subklass() && (!ik->is_valuetype() || ak->storage_properties().is_null_free())) {
2309 //assert(!UseExactTypes, "this code should be useless with exact types");
2310 // Add a dependence; if any subclass added we need to recompile
2311 if (!ik->is_final()) {
2312 phase->C->dependencies()->assert_leaf_type(ik);
2313 }
2314 // Return precise array klass
2315 return TypeKlassPtr::make(ak);
2316 }
2317 }
2318 return TypeKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0), false);
2319 } else if (ak->is_type_array_klass()) {
2320 //assert(!UseExactTypes, "this code should be useless with exact types");
2321 return TypeKlassPtr::make(ak); // These are always precise
2322 }
2323 }
2324 }
2325
2326 // Check for loading klass from an array klass
2327 const TypeKlassPtr *tkls = tp->isa_klassptr();
2328 if (tkls != NULL && !StressReflectiveCode) {
2329 if (!tkls->is_loaded()) {
2330 return _type; // Bail out if not loaded
2331 }
2332 ciKlass* klass = tkls->klass();
2333 if( klass->is_obj_array_klass() &&
2334 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2335 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2336 // // Always returning precise element type is incorrect,
2337 // // e.g., element type could be object and array may contain strings
2338 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2339
2340 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2341 // according to the element type's subclassing.
2342 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0), elem->flatten_array());
2343 } else if (klass->is_value_array_klass() &&
2344 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2345 ciKlass* elem = klass->as_value_array_klass()->element_klass();
2346 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0), true);
2347 }
2348 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2349 tkls->offset() == in_bytes(Klass::super_offset())) {
2350 ciKlass* sup = klass->as_instance_klass()->super();
2351 // The field is Klass::_super. Return its (constant) value.
2352 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2353 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2354 }
2355 }
2356
2357 // Bailout case
2358 return LoadNode::Value(phase);
2359 }
2360
2361 //------------------------------Identity---------------------------------------
2362 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2363 // Also feed through the klass in Allocate(...klass...)._klass.
2364 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2365 return klass_identity_common(phase);
2366 }
2367
2368 const Type* GetStoragePropertyNode::Value(PhaseGVN* phase) const {
2369 if (in(1) != NULL) {
2370 const Type* in1_t = phase->type(in(1));
2371 if (in1_t == Type::TOP) {
2372 return Type::TOP;
2373 }
2374 const TypeKlassPtr* tk = in1_t->make_ptr()->is_klassptr();
2375 ciArrayKlass* ak = tk->klass()->as_array_klass();
2376 ciKlass* elem = ak->element_klass();
2377 if (tk->klass_is_exact() || (!elem->is_java_lang_Object() && !elem->is_interface() && !elem->is_valuetype())) {
2378 int props_shift = in1_t->isa_narrowklass() ? oopDesc::narrow_storage_props_shift : oopDesc::wide_storage_props_shift;
2379 ArrayStorageProperties props = ak->storage_properties();
2380 intptr_t storage_properties = 0;
2381 if ((Opcode() == Op_GetFlattenedProperty && props.is_flattened()) ||
2382 (Opcode() == Op_GetNullFreeProperty && props.is_null_free())) {
2383 storage_properties = 1;
2384 }
2385 if (in1_t->isa_narrowklass()) {
2386 return TypeInt::make((int)storage_properties);
2387 }
2388 return TypeX::make(storage_properties);
2389 }
2390 }
2391 return bottom_type();
2392 }
2393
2394 Node* GetStoragePropertyNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2395 if (!can_reshape) {
2396 return NULL;
2397 }
2398 if (in(1) != NULL && in(1)->is_Phi()) {
2399 Node* phi = in(1);
2400 Node* r = phi->in(0);
2401 Node* new_phi = new PhiNode(r, bottom_type());
2402 for (uint i = 1; i < r->req(); i++) {
2403 Node* in = phi->in(i);
2404 if (in == NULL) continue;
2405 Node* n = clone();
2406 n->set_req(1, in);
2407 new_phi->init_req(i, phase->transform(n));
2408 }
2409 return new_phi;
2410 }
2411 return NULL;
2412 }
2413
2414 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2415 Node* x = LoadNode::Identity(phase);
2416 if (x != this) return x;
2417
2418 // Take apart the address into an oop and and offset.
2419 // Return 'this' if we cannot.
2420 Node* adr = in(MemNode::Address);
2421 intptr_t offset = 0;
2422 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2423 if (base == NULL) return this;
2424 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2425 if (toop == NULL) return this;
2426
2427 // Step over potential GC barrier for OopHandle resolve
2428 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2429 if (bs->is_gc_barrier_node(base)) {
2430 base = bs->step_over_gc_barrier(base);
2431 }
2432
2433 // We can fetch the klass directly through an AllocateNode.
2434 // This works even if the klass is not constant (clone or newArray).
2435 if (offset == oopDesc::klass_offset_in_bytes()) {
2436 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2437 if (allocated_klass != NULL) {
2438 return allocated_klass;
2439 }
2440 }
2441
2442 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2443 // See inline_native_Class_query for occurrences of these patterns.
2444 // Java Example: x.getClass().isAssignableFrom(y)
2445 //
2446 // This improves reflective code, often making the Class
2447 // mirror go completely dead. (Current exception: Class
2448 // mirrors may appear in debug info, but we could clean them out by
2449 // introducing a new debug info operator for Klass.java_mirror).
2450
2451 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2452 && offset == java_lang_Class::klass_offset_in_bytes()) {
2453 if (base->is_Load()) {
2454 Node* base2 = base->in(MemNode::Address);
2455 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2456 Node* adr2 = base2->in(MemNode::Address);
2457 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2458 if (tkls != NULL && !tkls->empty()
2459 && (tkls->klass()->is_instance_klass() ||
2460 tkls->klass()->is_array_klass())
2461 && adr2->is_AddP()
2462 ) {
2463 int mirror_field = in_bytes(Klass::java_mirror_offset());
2464 if (tkls->offset() == mirror_field) {
2465 return adr2->in(AddPNode::Base);
2466 }
2467 }
2468 }
2469 }
2470 }
2471
2472 return this;
2473 }
2474
2475
2476 //------------------------------Value------------------------------------------
2477 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2478 const Type *t = klass_value_common(phase);
2479 if (t == Type::TOP)
2480 return t;
2481
2482 return t->make_narrowklass();
2483 }
2484
2485 //------------------------------Identity---------------------------------------
2486 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2487 // Also feed through the klass in Allocate(...klass...)._klass.
2488 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2489 Node *x = klass_identity_common(phase);
2490
2491 const Type *t = phase->type( x );
2492 if( t == Type::TOP ) return x;
2493 if( t->isa_narrowklass()) return x;
2494 assert (!t->isa_narrowoop(), "no narrow oop here");
2495
2496 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2497 }
2498
2499 //------------------------------Value-----------------------------------------
2500 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2501 // Either input is TOP ==> the result is TOP
2502 const Type *t1 = phase->type( in(MemNode::Memory) );
2503 if( t1 == Type::TOP ) return Type::TOP;
2504 Node *adr = in(MemNode::Address);
2505 const Type *t2 = phase->type( adr );
2506 if( t2 == Type::TOP ) return Type::TOP;
2507 const TypePtr *tp = t2->is_ptr();
2508 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2509 const TypeAryPtr *tap = tp->isa_aryptr();
2510 if( !tap ) return _type;
2511 return tap->size();
2512 }
2513
2514 //-------------------------------Ideal---------------------------------------
2515 // Feed through the length in AllocateArray(...length...)._length.
2516 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2517 Node* p = MemNode::Ideal_common(phase, can_reshape);
2518 if (p) return (p == NodeSentinel) ? NULL : p;
2519
2520 // Take apart the address into an oop and and offset.
2521 // Return 'this' if we cannot.
2522 Node* adr = in(MemNode::Address);
2523 intptr_t offset = 0;
2524 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2525 if (base == NULL) return NULL;
2526 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2527 if (tary == NULL) return NULL;
2528
2529 // We can fetch the length directly through an AllocateArrayNode.
2530 // This works even if the length is not constant (clone or newArray).
2531 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2532 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2533 if (alloc != NULL) {
2534 Node* allocated_length = alloc->Ideal_length();
2535 Node* len = alloc->make_ideal_length(tary, phase);
2536 if (allocated_length != len) {
2537 // New CastII improves on this.
2538 return len;
2539 }
2540 }
2541 }
2542
2543 return NULL;
2544 }
2545
2546 //------------------------------Identity---------------------------------------
2547 // Feed through the length in AllocateArray(...length...)._length.
2548 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2549 Node* x = LoadINode::Identity(phase);
2550 if (x != this) return x;
2551
2552 // Take apart the address into an oop and and offset.
2553 // Return 'this' if we cannot.
2554 Node* adr = in(MemNode::Address);
2555 intptr_t offset = 0;
2556 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2557 if (base == NULL) return this;
2558 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2559 if (tary == NULL) return this;
2560
2561 // We can fetch the length directly through an AllocateArrayNode.
2562 // This works even if the length is not constant (clone or newArray).
2563 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2564 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2565 if (alloc != NULL) {
2566 Node* allocated_length = alloc->Ideal_length();
2567 // Do not allow make_ideal_length to allocate a CastII node.
2568 Node* len = alloc->make_ideal_length(tary, phase, false);
2569 if (allocated_length == len) {
2570 // Return allocated_length only if it would not be improved by a CastII.
2571 return allocated_length;
2572 }
2573 }
2574 }
2575
2576 return this;
2577
2578 }
2579
2580 //=============================================================================
2581 //---------------------------StoreNode::make-----------------------------------
2582 // Polymorphic factory method:
2583 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2584 assert((mo == unordered || mo == release), "unexpected");
2585 Compile* C = gvn.C;
2586 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2587 ctl != NULL, "raw memory operations should have control edge");
2588
2589 switch (bt) {
2590 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2591 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2592 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2593 case T_CHAR:
2594 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2595 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2596 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2597 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2598 case T_METADATA:
2599 case T_ADDRESS:
2600 case T_VALUETYPE:
2601 case T_OBJECT:
2602 #ifdef _LP64
2603 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2604 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2605 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2606 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2607 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2608 adr->bottom_type()->isa_rawptr())) {
2609 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2610 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2611 }
2612 #endif
2613 {
2614 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2615 }
2616 default:
2617 ShouldNotReachHere();
2618 return (StoreNode*)NULL;
2619 }
2620 }
2621
2622 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2623 bool require_atomic = true;
2624 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2625 }
2626
2627 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2628 bool require_atomic = true;
2629 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2630 }
2631
2632
2633 //--------------------------bottom_type----------------------------------------
2634 const Type *StoreNode::bottom_type() const {
2635 return Type::MEMORY;
2636 }
2637
2638 //------------------------------hash-------------------------------------------
2639 uint StoreNode::hash() const {
2640 // unroll addition of interesting fields
2641 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2642
2643 // Since they are not commoned, do not hash them:
2644 return NO_HASH;
2645 }
2646
2647 //------------------------------Ideal------------------------------------------
2648 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2649 // When a store immediately follows a relevant allocation/initialization,
2650 // try to capture it into the initialization, or hoist it above.
2651 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2652 Node* p = MemNode::Ideal_common(phase, can_reshape);
2653 if (p) return (p == NodeSentinel) ? NULL : p;
2654
2655 Node* mem = in(MemNode::Memory);
2656 Node* address = in(MemNode::Address);
2657 // Back-to-back stores to same address? Fold em up. Generally
2658 // unsafe if I have intervening uses... Also disallowed for StoreCM
2659 // since they must follow each StoreP operation. Redundant StoreCMs
2660 // are eliminated just before matching in final_graph_reshape.
2661 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::VALUES) {
2662 Node* st = mem;
2663 // If Store 'st' has more than one use, we cannot fold 'st' away.
2664 // For example, 'st' might be the final state at a conditional
2665 // return. Or, 'st' might be used by some node which is live at
2666 // the same time 'st' is live, which might be unschedulable. So,
2667 // require exactly ONE user until such time as we clone 'mem' for
2668 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2669 // true).
2670 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2671 // Looking at a dead closed cycle of memory?
2672 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2673 assert(Opcode() == st->Opcode() ||
2674 st->Opcode() == Op_StoreVector ||
2675 Opcode() == Op_StoreVector ||
2676 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2677 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2678 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2679 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2680 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2681 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2682
2683 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2684 st->as_Store()->memory_size() <= this->memory_size()) {
2685 Node* use = st->raw_out(0);
2686 phase->igvn_rehash_node_delayed(use);
2687 if (can_reshape) {
2688 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2689 } else {
2690 // It's OK to do this in the parser, since DU info is always accurate,
2691 // and the parser always refers to nodes via SafePointNode maps.
2692 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2693 }
2694 return this;
2695 }
2696 st = st->in(MemNode::Memory);
2697 }
2698 }
2699
2700
2701 // Capture an unaliased, unconditional, simple store into an initializer.
2702 // Or, if it is independent of the allocation, hoist it above the allocation.
2703 if (ReduceFieldZeroing && /*can_reshape &&*/
2704 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2705 InitializeNode* init = mem->in(0)->as_Initialize();
2706 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2707 if (offset > 0) {
2708 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2709 // If the InitializeNode captured me, it made a raw copy of me,
2710 // and I need to disappear.
2711 if (moved != NULL) {
2712 // %%% hack to ensure that Ideal returns a new node:
2713 mem = MergeMemNode::make(mem);
2714 return mem; // fold me away
2715 }
2716 }
2717 }
2718
2719 return NULL; // No further progress
2720 }
2721
2722 //------------------------------Value-----------------------------------------
2723 const Type* StoreNode::Value(PhaseGVN* phase) const {
2724 // Either input is TOP ==> the result is TOP
2725 const Type *t1 = phase->type( in(MemNode::Memory) );
2726 if( t1 == Type::TOP ) return Type::TOP;
2727 const Type *t2 = phase->type( in(MemNode::Address) );
2728 if( t2 == Type::TOP ) return Type::TOP;
2729 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2730 if( t3 == Type::TOP ) return Type::TOP;
2731 return Type::MEMORY;
2732 }
2733
2734 //------------------------------Identity---------------------------------------
2735 // Remove redundant stores:
2736 // Store(m, p, Load(m, p)) changes to m.
2737 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2738 Node* StoreNode::Identity(PhaseGVN* phase) {
2739 Node* mem = in(MemNode::Memory);
2740 Node* adr = in(MemNode::Address);
2741 Node* val = in(MemNode::ValueIn);
2742
2743 Node* result = this;
2744
2745 // Load then Store? Then the Store is useless
2746 if (val->is_Load() &&
2747 val->in(MemNode::Address)->eqv_uncast(adr) &&
2748 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2749 val->as_Load()->store_Opcode() == Opcode()) {
2750 result = mem;
2751 }
2752
2753 // Two stores in a row of the same value?
2754 if (result == this &&
2755 mem->is_Store() &&
2756 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2757 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2758 mem->Opcode() == Opcode()) {
2759 result = mem;
2760 }
2761
2762 // Store of zero anywhere into a freshly-allocated object?
2763 // Then the store is useless.
2764 // (It must already have been captured by the InitializeNode.)
2765 if (result == this && ReduceFieldZeroing) {
2766 // a newly allocated object is already all-zeroes everywhere
2767 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2768 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2769 assert(!phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == NULL, "storing null to value array is forbidden");
2770 result = mem;
2771 }
2772
2773 if (result == this) {
2774 // the store may also apply to zero-bits in an earlier object
2775 Node* prev_mem = find_previous_store(phase);
2776 // Steps (a), (b): Walk past independent stores to find an exact match.
2777 if (prev_mem != NULL) {
2778 Node* prev_val = can_see_stored_value(prev_mem, phase);
2779 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2780 // prev_val and val might differ by a cast; it would be good
2781 // to keep the more informative of the two.
2782 if (phase->type(val)->is_zero_type()) {
2783 result = mem;
2784 } else if (prev_mem->is_Proj() && prev_mem->in(0)->is_Initialize()) {
2785 InitializeNode* init = prev_mem->in(0)->as_Initialize();
2786 AllocateNode* alloc = init->allocation();
2787 if (alloc != NULL && alloc->in(AllocateNode::DefaultValue) == val) {
2788 result = mem;
2789 }
2790 }
2791 }
2792 }
2793 }
2794 }
2795
2796 if (result != this && phase->is_IterGVN() != NULL) {
2797 MemBarNode* trailing = trailing_membar();
2798 if (trailing != NULL) {
2799 #ifdef ASSERT
2800 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2801 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2802 #endif
2803 PhaseIterGVN* igvn = phase->is_IterGVN();
2804 trailing->remove(igvn);
2805 }
2806 }
2807
2808 return result;
2809 }
2810
2811 //------------------------------match_edge-------------------------------------
2812 // Do we Match on this edge index or not? Match only memory & value
2813 uint StoreNode::match_edge(uint idx) const {
2814 return idx == MemNode::Address || idx == MemNode::ValueIn;
2815 }
2816
2817 //------------------------------cmp--------------------------------------------
2818 // Do not common stores up together. They generally have to be split
2819 // back up anyways, so do not bother.
2820 bool StoreNode::cmp( const Node &n ) const {
2821 return (&n == this); // Always fail except on self
2822 }
2823
2824 //------------------------------Ideal_masked_input-----------------------------
2825 // Check for a useless mask before a partial-word store
2826 // (StoreB ... (AndI valIn conIa) )
2827 // If (conIa & mask == mask) this simplifies to
2828 // (StoreB ... (valIn) )
2829 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2830 Node *val = in(MemNode::ValueIn);
2831 if( val->Opcode() == Op_AndI ) {
2832 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2833 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2834 set_req(MemNode::ValueIn, val->in(1));
2835 return this;
2836 }
2837 }
2838 return NULL;
2839 }
2840
2841
2842 //------------------------------Ideal_sign_extended_input----------------------
2843 // Check for useless sign-extension before a partial-word store
2844 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2845 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2846 // (StoreB ... (valIn) )
2847 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2848 Node *val = in(MemNode::ValueIn);
2849 if( val->Opcode() == Op_RShiftI ) {
2850 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2851 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2852 Node *shl = val->in(1);
2853 if( shl->Opcode() == Op_LShiftI ) {
2854 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2855 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2856 set_req(MemNode::ValueIn, shl->in(1));
2857 return this;
2858 }
2859 }
2860 }
2861 }
2862 return NULL;
2863 }
2864
2865 //------------------------------value_never_loaded-----------------------------------
2866 // Determine whether there are any possible loads of the value stored.
2867 // For simplicity, we actually check if there are any loads from the
2868 // address stored to, not just for loads of the value stored by this node.
2869 //
2870 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2871 Node *adr = in(Address);
2872 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2873 if (adr_oop == NULL)
2874 return false;
2875 if (!adr_oop->is_known_instance_field())
2876 return false; // if not a distinct instance, there may be aliases of the address
2877 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2878 Node *use = adr->fast_out(i);
2879 if (use->is_Load() || use->is_LoadStore()) {
2880 return false;
2881 }
2882 }
2883 return true;
2884 }
2885
2886 MemBarNode* StoreNode::trailing_membar() const {
2887 if (is_release()) {
2888 MemBarNode* trailing_mb = NULL;
2889 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2890 Node* u = fast_out(i);
2891 if (u->is_MemBar()) {
2892 if (u->as_MemBar()->trailing_store()) {
2893 assert(u->Opcode() == Op_MemBarVolatile, "");
2894 assert(trailing_mb == NULL, "only one");
2895 trailing_mb = u->as_MemBar();
2896 #ifdef ASSERT
2897 Node* leading = u->as_MemBar()->leading_membar();
2898 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2899 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2900 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2901 #endif
2902 } else {
2903 assert(u->as_MemBar()->standalone(), "");
2904 }
2905 }
2906 }
2907 return trailing_mb;
2908 }
2909 return NULL;
2910 }
2911
2912
2913 //=============================================================================
2914 //------------------------------Ideal------------------------------------------
2915 // If the store is from an AND mask that leaves the low bits untouched, then
2916 // we can skip the AND operation. If the store is from a sign-extension
2917 // (a left shift, then right shift) we can skip both.
2918 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2919 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2920 if( progress != NULL ) return progress;
2921
2922 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2923 if( progress != NULL ) return progress;
2924
2925 // Finally check the default case
2926 return StoreNode::Ideal(phase, can_reshape);
2927 }
2928
2929 //=============================================================================
2930 //------------------------------Ideal------------------------------------------
2931 // If the store is from an AND mask that leaves the low bits untouched, then
2932 // we can skip the AND operation
2933 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2934 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2935 if( progress != NULL ) return progress;
2936
2937 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2938 if( progress != NULL ) return progress;
2939
2940 // Finally check the default case
2941 return StoreNode::Ideal(phase, can_reshape);
2942 }
2943
2944 //=============================================================================
2945 //------------------------------Identity---------------------------------------
2946 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2947 // No need to card mark when storing a null ptr
2948 Node* my_store = in(MemNode::OopStore);
2949 if (my_store->is_Store()) {
2950 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2951 if( t1 == TypePtr::NULL_PTR ) {
2952 return in(MemNode::Memory);
2953 }
2954 }
2955 return this;
2956 }
2957
2958 //=============================================================================
2959 //------------------------------Ideal---------------------------------------
2960 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2961 Node* progress = StoreNode::Ideal(phase, can_reshape);
2962 if (progress != NULL) return progress;
2963
2964 Node* my_store = in(MemNode::OopStore);
2965 if (my_store->is_MergeMem()) {
2966 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2967 set_req(MemNode::OopStore, mem);
2968 return this;
2969 }
2970
2971 return NULL;
2972 }
2973
2974 //------------------------------Value-----------------------------------------
2975 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2976 // Either input is TOP ==> the result is TOP
2977 const Type *t = phase->type( in(MemNode::Memory) );
2978 if( t == Type::TOP ) return Type::TOP;
2979 t = phase->type( in(MemNode::Address) );
2980 if( t == Type::TOP ) return Type::TOP;
2981 t = phase->type( in(MemNode::ValueIn) );
2982 if( t == Type::TOP ) return Type::TOP;
2983 // If extra input is TOP ==> the result is TOP
2984 t = phase->type( in(MemNode::OopStore) );
2985 if( t == Type::TOP ) return Type::TOP;
2986
2987 return StoreNode::Value( phase );
2988 }
2989
2990
2991 //=============================================================================
2992 //----------------------------------SCMemProjNode------------------------------
2993 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2994 {
2995 return bottom_type();
2996 }
2997
2998 //=============================================================================
2999 //----------------------------------LoadStoreNode------------------------------
3000 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3001 : Node(required),
3002 _type(rt),
3003 _adr_type(at),
3004 _has_barrier(false)
3005 {
3006 init_req(MemNode::Control, c );
3007 init_req(MemNode::Memory , mem);
3008 init_req(MemNode::Address, adr);
3009 init_req(MemNode::ValueIn, val);
3010 init_class_id(Class_LoadStore);
3011 }
3012
3013 uint LoadStoreNode::ideal_reg() const {
3014 return _type->ideal_reg();
3015 }
3016
3017 bool LoadStoreNode::result_not_used() const {
3018 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3019 Node *x = fast_out(i);
3020 if (x->Opcode() == Op_SCMemProj) continue;
3021 return false;
3022 }
3023 return true;
3024 }
3025
3026 MemBarNode* LoadStoreNode::trailing_membar() const {
3027 MemBarNode* trailing = NULL;
3028 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3029 Node* u = fast_out(i);
3030 if (u->is_MemBar()) {
3031 if (u->as_MemBar()->trailing_load_store()) {
3032 assert(u->Opcode() == Op_MemBarAcquire, "");
3033 assert(trailing == NULL, "only one");
3034 trailing = u->as_MemBar();
3035 #ifdef ASSERT
3036 Node* leading = trailing->leading_membar();
3037 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3038 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3039 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3040 #endif
3041 } else {
3042 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3043 }
3044 }
3045 }
3046
3047 return trailing;
3048 }
3049
3050 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3051
3052 //=============================================================================
3053 //----------------------------------LoadStoreConditionalNode--------------------
3054 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
3055 init_req(ExpectedIn, ex );
3056 }
3057
3058 //=============================================================================
3059 //-------------------------------adr_type--------------------------------------
3060 const TypePtr* ClearArrayNode::adr_type() const {
3061 Node *adr = in(3);
3062 if (adr == NULL) return NULL; // node is dead
3063 return MemNode::calculate_adr_type(adr->bottom_type());
3064 }
3065
3066 //------------------------------match_edge-------------------------------------
3067 // Do we Match on this edge index or not? Do not match memory
3068 uint ClearArrayNode::match_edge(uint idx) const {
3069 return idx > 1;
3070 }
3071
3072 //------------------------------Identity---------------------------------------
3073 // Clearing a zero length array does nothing
3074 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3075 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3076 }
3077
3078 //------------------------------Idealize---------------------------------------
3079 // Clearing a short array is faster with stores
3080 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3081 // Already know this is a large node, do not try to ideal it
3082 if (!IdealizeClearArrayNode || _is_large) return NULL;
3083
3084 const int unit = BytesPerLong;
3085 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3086 if (!t) return NULL;
3087 if (!t->is_con()) return NULL;
3088 intptr_t raw_count = t->get_con();
3089 intptr_t size = raw_count;
3090 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3091 // Clearing nothing uses the Identity call.
3092 // Negative clears are possible on dead ClearArrays
3093 // (see jck test stmt114.stmt11402.val).
3094 if (size <= 0 || size % unit != 0) return NULL;
3095 intptr_t count = size / unit;
3096 // Length too long; communicate this to matchers and assemblers.
3097 // Assemblers are responsible to produce fast hardware clears for it.
3098 if (size > InitArrayShortSize) {
3099 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
3100 }
3101 Node *mem = in(1);
3102 if( phase->type(mem)==Type::TOP ) return NULL;
3103 Node *adr = in(3);
3104 const Type* at = phase->type(adr);
3105 if( at==Type::TOP ) return NULL;
3106 const TypePtr* atp = at->isa_ptr();
3107 // adjust atp to be the correct array element address type
3108 if (atp == NULL) atp = TypePtr::BOTTOM;
3109 else atp = atp->add_offset(Type::OffsetBot);
3110 // Get base for derived pointer purposes
3111 if( adr->Opcode() != Op_AddP ) Unimplemented();
3112 Node *base = adr->in(1);
3113
3114 Node *val = in(4);
3115 Node *off = phase->MakeConX(BytesPerLong);
3116 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3117 count--;
3118 while( count-- ) {
3119 mem = phase->transform(mem);
3120 adr = phase->transform(new AddPNode(base,adr,off));
3121 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3122 }
3123 return mem;
3124 }
3125
3126 //----------------------------step_through----------------------------------
3127 // Return allocation input memory edge if it is different instance
3128 // or itself if it is the one we are looking for.
3129 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3130 Node* n = *np;
3131 assert(n->is_ClearArray(), "sanity");
3132 intptr_t offset;
3133 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3134 // This method is called only before Allocate nodes are expanded
3135 // during macro nodes expansion. Before that ClearArray nodes are
3136 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3137 // Allocate nodes are expanded) which follows allocations.
3138 assert(alloc != NULL, "should have allocation");
3139 if (alloc->_idx == instance_id) {
3140 // Can not bypass initialization of the instance we are looking for.
3141 return false;
3142 }
3143 // Otherwise skip it.
3144 InitializeNode* init = alloc->initialization();
3145 if (init != NULL)
3146 *np = init->in(TypeFunc::Memory);
3147 else
3148 *np = alloc->in(TypeFunc::Memory);
3149 return true;
3150 }
3151
3152 //----------------------------clear_memory-------------------------------------
3153 // Generate code to initialize object storage to zero.
3154 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3155 Node* val,
3156 Node* raw_val,
3157 intptr_t start_offset,
3158 Node* end_offset,
3159 PhaseGVN* phase) {
3160 intptr_t offset = start_offset;
3161
3162 int unit = BytesPerLong;
3163 if ((offset % unit) != 0) {
3164 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3165 adr = phase->transform(adr);
3166 const TypePtr* atp = TypeRawPtr::BOTTOM;
3167 if (val != NULL) {
3168 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3169 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3170 } else {
3171 assert(raw_val == NULL, "val may not be null");
3172 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3173 }
3174 mem = phase->transform(mem);
3175 offset += BytesPerInt;
3176 }
3177 assert((offset % unit) == 0, "");
3178
3179 // Initialize the remaining stuff, if any, with a ClearArray.
3180 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3181 }
3182
3183 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3184 Node* raw_val,
3185 Node* start_offset,
3186 Node* end_offset,
3187 PhaseGVN* phase) {
3188 if (start_offset == end_offset) {
3189 // nothing to do
3190 return mem;
3191 }
3192
3193 int unit = BytesPerLong;
3194 Node* zbase = start_offset;
3195 Node* zend = end_offset;
3196
3197 // Scale to the unit required by the CPU:
3198 if (!Matcher::init_array_count_is_in_bytes) {
3199 Node* shift = phase->intcon(exact_log2(unit));
3200 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3201 zend = phase->transform(new URShiftXNode(zend, shift) );
3202 }
3203
3204 // Bulk clear double-words
3205 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3206 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3207 if (raw_val == NULL) {
3208 raw_val = phase->MakeConX(0);
3209 }
3210 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3211 return phase->transform(mem);
3212 }
3213
3214 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3215 Node* val,
3216 Node* raw_val,
3217 intptr_t start_offset,
3218 intptr_t end_offset,
3219 PhaseGVN* phase) {
3220 if (start_offset == end_offset) {
3221 // nothing to do
3222 return mem;
3223 }
3224
3225 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3226 intptr_t done_offset = end_offset;
3227 if ((done_offset % BytesPerLong) != 0) {
3228 done_offset -= BytesPerInt;
3229 }
3230 if (done_offset > start_offset) {
3231 mem = clear_memory(ctl, mem, dest, val, raw_val,
3232 start_offset, phase->MakeConX(done_offset), phase);
3233 }
3234 if (done_offset < end_offset) { // emit the final 32-bit store
3235 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3236 adr = phase->transform(adr);
3237 const TypePtr* atp = TypeRawPtr::BOTTOM;
3238 if (val != NULL) {
3239 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3240 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3241 } else {
3242 assert(raw_val == NULL, "val may not be null");
3243 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3244 }
3245 mem = phase->transform(mem);
3246 done_offset += BytesPerInt;
3247 }
3248 assert(done_offset == end_offset, "");
3249 return mem;
3250 }
3251
3252 //=============================================================================
3253 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3254 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3255 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3256 #ifdef ASSERT
3257 , _pair_idx(0)
3258 #endif
3259 {
3260 init_class_id(Class_MemBar);
3261 Node* top = C->top();
3262 init_req(TypeFunc::I_O,top);
3263 init_req(TypeFunc::FramePtr,top);
3264 init_req(TypeFunc::ReturnAdr,top);
3265 if (precedent != NULL)
3266 init_req(TypeFunc::Parms, precedent);
3267 }
3268
3269 //------------------------------cmp--------------------------------------------
3270 uint MemBarNode::hash() const { return NO_HASH; }
3271 bool MemBarNode::cmp( const Node &n ) const {
3272 return (&n == this); // Always fail except on self
3273 }
3274
3275 //------------------------------make-------------------------------------------
3276 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3277 switch (opcode) {
3278 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3279 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3280 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3281 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3282 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3283 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3284 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3285 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3286 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3287 case Op_Initialize: return new InitializeNode(C, atp, pn);
3288 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3289 default: ShouldNotReachHere(); return NULL;
3290 }
3291 }
3292
3293 void MemBarNode::remove(PhaseIterGVN *igvn) {
3294 if (outcnt() != 2) {
3295 return;
3296 }
3297 if (trailing_store() || trailing_load_store()) {
3298 MemBarNode* leading = leading_membar();
3299 if (leading != NULL) {
3300 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3301 leading->remove(igvn);
3302 }
3303 }
3304 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3305 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3306 }
3307
3308 //------------------------------Ideal------------------------------------------
3309 // Return a node which is more "ideal" than the current node. Strip out
3310 // control copies
3311 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3312 if (remove_dead_region(phase, can_reshape)) return this;
3313 // Don't bother trying to transform a dead node
3314 if (in(0) && in(0)->is_top()) {
3315 return NULL;
3316 }
3317
3318 bool progress = false;
3319 // Eliminate volatile MemBars for scalar replaced objects.
3320 if (can_reshape && req() == (Precedent+1)) {
3321 bool eliminate = false;
3322 int opc = Opcode();
3323 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3324 // Volatile field loads and stores.
3325 Node* my_mem = in(MemBarNode::Precedent);
3326 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3327 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3328 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3329 // replace this Precedent (decodeN) with the Load instead.
3330 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3331 Node* load_node = my_mem->in(1);
3332 set_req(MemBarNode::Precedent, load_node);
3333 phase->is_IterGVN()->_worklist.push(my_mem);
3334 my_mem = load_node;
3335 } else {
3336 assert(my_mem->unique_out() == this, "sanity");
3337 del_req(Precedent);
3338 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3339 my_mem = NULL;
3340 }
3341 progress = true;
3342 }
3343 if (my_mem != NULL && my_mem->is_Mem()) {
3344 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3345 // Check for scalar replaced object reference.
3346 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3347 t_oop->offset() != Type::OffsetBot &&
3348 t_oop->offset() != Type::OffsetTop) {
3349 eliminate = true;
3350 }
3351 }
3352 } else if (opc == Op_MemBarRelease) {
3353 // Final field stores.
3354 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3355 if ((alloc != NULL) && alloc->is_Allocate() &&
3356 alloc->as_Allocate()->does_not_escape_thread()) {
3357 // The allocated object does not escape.
3358 eliminate = true;
3359 }
3360 }
3361 if (eliminate) {
3362 // Replace MemBar projections by its inputs.
3363 PhaseIterGVN* igvn = phase->is_IterGVN();
3364 remove(igvn);
3365 // Must return either the original node (now dead) or a new node
3366 // (Do not return a top here, since that would break the uniqueness of top.)
3367 return new ConINode(TypeInt::ZERO);
3368 }
3369 }
3370 return progress ? this : NULL;
3371 }
3372
3373 //------------------------------Value------------------------------------------
3374 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3375 if( !in(0) ) return Type::TOP;
3376 if( phase->type(in(0)) == Type::TOP )
3377 return Type::TOP;
3378 return TypeTuple::MEMBAR;
3379 }
3380
3381 //------------------------------match------------------------------------------
3382 // Construct projections for memory.
3383 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3384 switch (proj->_con) {
3385 case TypeFunc::Control:
3386 case TypeFunc::Memory:
3387 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3388 }
3389 ShouldNotReachHere();
3390 return NULL;
3391 }
3392
3393 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3394 trailing->_kind = TrailingStore;
3395 leading->_kind = LeadingStore;
3396 #ifdef ASSERT
3397 trailing->_pair_idx = leading->_idx;
3398 leading->_pair_idx = leading->_idx;
3399 #endif
3400 }
3401
3402 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3403 trailing->_kind = TrailingLoadStore;
3404 leading->_kind = LeadingLoadStore;
3405 #ifdef ASSERT
3406 trailing->_pair_idx = leading->_idx;
3407 leading->_pair_idx = leading->_idx;
3408 #endif
3409 }
3410
3411 MemBarNode* MemBarNode::trailing_membar() const {
3412 ResourceMark rm;
3413 Node* trailing = (Node*)this;
3414 VectorSet seen(Thread::current()->resource_area());
3415 Node_Stack multis(0);
3416 do {
3417 Node* c = trailing;
3418 uint i = 0;
3419 do {
3420 trailing = NULL;
3421 for (; i < c->outcnt(); i++) {
3422 Node* next = c->raw_out(i);
3423 if (next != c && next->is_CFG()) {
3424 if (c->is_MultiBranch()) {
3425 if (multis.node() == c) {
3426 multis.set_index(i+1);
3427 } else {
3428 multis.push(c, i+1);
3429 }
3430 }
3431 trailing = next;
3432 break;
3433 }
3434 }
3435 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3436 break;
3437 }
3438 while (multis.size() > 0) {
3439 c = multis.node();
3440 i = multis.index();
3441 if (i < c->req()) {
3442 break;
3443 }
3444 multis.pop();
3445 }
3446 } while (multis.size() > 0);
3447 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3448
3449 MemBarNode* mb = trailing->as_MemBar();
3450 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3451 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3452 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3453 return mb;
3454 }
3455
3456 MemBarNode* MemBarNode::leading_membar() const {
3457 ResourceMark rm;
3458 VectorSet seen(Thread::current()->resource_area());
3459 Node_Stack regions(0);
3460 Node* leading = in(0);
3461 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3462 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3463 leading = NULL;
3464 while (regions.size() > 0 && leading == NULL) {
3465 Node* r = regions.node();
3466 uint i = regions.index();
3467 if (i < r->req()) {
3468 leading = r->in(i);
3469 regions.set_index(i+1);
3470 } else {
3471 regions.pop();
3472 }
3473 }
3474 if (leading == NULL) {
3475 assert(regions.size() == 0, "all paths should have been tried");
3476 return NULL;
3477 }
3478 }
3479 if (leading->is_Region()) {
3480 regions.push(leading, 2);
3481 leading = leading->in(1);
3482 } else {
3483 leading = leading->in(0);
3484 }
3485 }
3486 #ifdef ASSERT
3487 Unique_Node_List wq;
3488 wq.push((Node*)this);
3489 uint found = 0;
3490 for (uint i = 0; i < wq.size(); i++) {
3491 Node* n = wq.at(i);
3492 if (n->is_Region()) {
3493 for (uint j = 1; j < n->req(); j++) {
3494 Node* in = n->in(j);
3495 if (in != NULL && !in->is_top()) {
3496 wq.push(in);
3497 }
3498 }
3499 } else {
3500 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3501 assert(n == leading, "consistency check failed");
3502 found++;
3503 } else {
3504 Node* in = n->in(0);
3505 if (in != NULL && !in->is_top()) {
3506 wq.push(in);
3507 }
3508 }
3509 }
3510 }
3511 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3512 #endif
3513 if (leading == NULL) {
3514 return NULL;
3515 }
3516 MemBarNode* mb = leading->as_MemBar();
3517 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3518 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3519 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3520 return mb;
3521 }
3522
3523 //===========================InitializeNode====================================
3524 // SUMMARY:
3525 // This node acts as a memory barrier on raw memory, after some raw stores.
3526 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3527 // The Initialize can 'capture' suitably constrained stores as raw inits.
3528 // It can coalesce related raw stores into larger units (called 'tiles').
3529 // It can avoid zeroing new storage for memory units which have raw inits.
3530 // At macro-expansion, it is marked 'complete', and does not optimize further.
3531 //
3532 // EXAMPLE:
3533 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3534 // ctl = incoming control; mem* = incoming memory
3535 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3536 // First allocate uninitialized memory and fill in the header:
3537 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3538 // ctl := alloc.Control; mem* := alloc.Memory*
3539 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3540 // Then initialize to zero the non-header parts of the raw memory block:
3541 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3542 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3543 // After the initialize node executes, the object is ready for service:
3544 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3545 // Suppose its body is immediately initialized as {1,2}:
3546 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3547 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3548 // mem.SLICE(#short[*]) := store2
3549 //
3550 // DETAILS:
3551 // An InitializeNode collects and isolates object initialization after
3552 // an AllocateNode and before the next possible safepoint. As a
3553 // memory barrier (MemBarNode), it keeps critical stores from drifting
3554 // down past any safepoint or any publication of the allocation.
3555 // Before this barrier, a newly-allocated object may have uninitialized bits.
3556 // After this barrier, it may be treated as a real oop, and GC is allowed.
3557 //
3558 // The semantics of the InitializeNode include an implicit zeroing of
3559 // the new object from object header to the end of the object.
3560 // (The object header and end are determined by the AllocateNode.)
3561 //
3562 // Certain stores may be added as direct inputs to the InitializeNode.
3563 // These stores must update raw memory, and they must be to addresses
3564 // derived from the raw address produced by AllocateNode, and with
3565 // a constant offset. They must be ordered by increasing offset.
3566 // The first one is at in(RawStores), the last at in(req()-1).
3567 // Unlike most memory operations, they are not linked in a chain,
3568 // but are displayed in parallel as users of the rawmem output of
3569 // the allocation.
3570 //
3571 // (See comments in InitializeNode::capture_store, which continue
3572 // the example given above.)
3573 //
3574 // When the associated Allocate is macro-expanded, the InitializeNode
3575 // may be rewritten to optimize collected stores. A ClearArrayNode
3576 // may also be created at that point to represent any required zeroing.
3577 // The InitializeNode is then marked 'complete', prohibiting further
3578 // capturing of nearby memory operations.
3579 //
3580 // During macro-expansion, all captured initializations which store
3581 // constant values of 32 bits or smaller are coalesced (if advantageous)
3582 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3583 // initialized in fewer memory operations. Memory words which are
3584 // covered by neither tiles nor non-constant stores are pre-zeroed
3585 // by explicit stores of zero. (The code shape happens to do all
3586 // zeroing first, then all other stores, with both sequences occurring
3587 // in order of ascending offsets.)
3588 //
3589 // Alternatively, code may be inserted between an AllocateNode and its
3590 // InitializeNode, to perform arbitrary initialization of the new object.
3591 // E.g., the object copying intrinsics insert complex data transfers here.
3592 // The initialization must then be marked as 'complete' disable the
3593 // built-in zeroing semantics and the collection of initializing stores.
3594 //
3595 // While an InitializeNode is incomplete, reads from the memory state
3596 // produced by it are optimizable if they match the control edge and
3597 // new oop address associated with the allocation/initialization.
3598 // They return a stored value (if the offset matches) or else zero.
3599 // A write to the memory state, if it matches control and address,
3600 // and if it is to a constant offset, may be 'captured' by the
3601 // InitializeNode. It is cloned as a raw memory operation and rewired
3602 // inside the initialization, to the raw oop produced by the allocation.
3603 // Operations on addresses which are provably distinct (e.g., to
3604 // other AllocateNodes) are allowed to bypass the initialization.
3605 //
3606 // The effect of all this is to consolidate object initialization
3607 // (both arrays and non-arrays, both piecewise and bulk) into a
3608 // single location, where it can be optimized as a unit.
3609 //
3610 // Only stores with an offset less than TrackedInitializationLimit words
3611 // will be considered for capture by an InitializeNode. This puts a
3612 // reasonable limit on the complexity of optimized initializations.
3613
3614 //---------------------------InitializeNode------------------------------------
3615 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3616 : MemBarNode(C, adr_type, rawoop),
3617 _is_complete(Incomplete), _does_not_escape(false)
3618 {
3619 init_class_id(Class_Initialize);
3620
3621 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3622 assert(in(RawAddress) == rawoop, "proper init");
3623 // Note: allocation() can be NULL, for secondary initialization barriers
3624 }
3625
3626 // Since this node is not matched, it will be processed by the
3627 // register allocator. Declare that there are no constraints
3628 // on the allocation of the RawAddress edge.
3629 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3630 // This edge should be set to top, by the set_complete. But be conservative.
3631 if (idx == InitializeNode::RawAddress)
3632 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3633 return RegMask::Empty;
3634 }
3635
3636 Node* InitializeNode::memory(uint alias_idx) {
3637 Node* mem = in(Memory);
3638 if (mem->is_MergeMem()) {
3639 return mem->as_MergeMem()->memory_at(alias_idx);
3640 } else {
3641 // incoming raw memory is not split
3642 return mem;
3643 }
3644 }
3645
3646 bool InitializeNode::is_non_zero() {
3647 if (is_complete()) return false;
3648 remove_extra_zeroes();
3649 return (req() > RawStores);
3650 }
3651
3652 void InitializeNode::set_complete(PhaseGVN* phase) {
3653 assert(!is_complete(), "caller responsibility");
3654 _is_complete = Complete;
3655
3656 // After this node is complete, it contains a bunch of
3657 // raw-memory initializations. There is no need for
3658 // it to have anything to do with non-raw memory effects.
3659 // Therefore, tell all non-raw users to re-optimize themselves,
3660 // after skipping the memory effects of this initialization.
3661 PhaseIterGVN* igvn = phase->is_IterGVN();
3662 if (igvn) igvn->add_users_to_worklist(this);
3663 }
3664
3665 // convenience function
3666 // return false if the init contains any stores already
3667 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3668 InitializeNode* init = initialization();
3669 if (init == NULL || init->is_complete()) {
3670 return false;
3671 }
3672 init->remove_extra_zeroes();
3673 // for now, if this allocation has already collected any inits, bail:
3674 if (init->is_non_zero()) return false;
3675 init->set_complete(phase);
3676 return true;
3677 }
3678
3679 void InitializeNode::remove_extra_zeroes() {
3680 if (req() == RawStores) return;
3681 Node* zmem = zero_memory();
3682 uint fill = RawStores;
3683 for (uint i = fill; i < req(); i++) {
3684 Node* n = in(i);
3685 if (n->is_top() || n == zmem) continue; // skip
3686 if (fill < i) set_req(fill, n); // compact
3687 ++fill;
3688 }
3689 // delete any empty spaces created:
3690 while (fill < req()) {
3691 del_req(fill);
3692 }
3693 }
3694
3695 // Helper for remembering which stores go with which offsets.
3696 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3697 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3698 intptr_t offset = -1;
3699 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3700 phase, offset);
3701 if (base == NULL) return -1; // something is dead,
3702 if (offset < 0) return -1; // dead, dead
3703 return offset;
3704 }
3705
3706 // Helper for proving that an initialization expression is
3707 // "simple enough" to be folded into an object initialization.
3708 // Attempts to prove that a store's initial value 'n' can be captured
3709 // within the initialization without creating a vicious cycle, such as:
3710 // { Foo p = new Foo(); p.next = p; }
3711 // True for constants and parameters and small combinations thereof.
3712 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3713 if (n == NULL) return true; // (can this really happen?)
3714 if (n->is_Proj()) n = n->in(0);
3715 if (n == this) return false; // found a cycle
3716 if (n->is_Con()) return true;
3717 if (n->is_Start()) return true; // params, etc., are OK
3718 if (n->is_Root()) return true; // even better
3719
3720 Node* ctl = n->in(0);
3721 if (ctl != NULL && !ctl->is_top()) {
3722 if (ctl->is_Proj()) ctl = ctl->in(0);
3723 if (ctl == this) return false;
3724
3725 // If we already know that the enclosing memory op is pinned right after
3726 // the init, then any control flow that the store has picked up
3727 // must have preceded the init, or else be equal to the init.
3728 // Even after loop optimizations (which might change control edges)
3729 // a store is never pinned *before* the availability of its inputs.
3730 if (!MemNode::all_controls_dominate(n, this))
3731 return false; // failed to prove a good control
3732 }
3733
3734 // Check data edges for possible dependencies on 'this'.
3735 if ((count += 1) > 20) return false; // complexity limit
3736 for (uint i = 1; i < n->req(); i++) {
3737 Node* m = n->in(i);
3738 if (m == NULL || m == n || m->is_top()) continue;
3739 uint first_i = n->find_edge(m);
3740 if (i != first_i) continue; // process duplicate edge just once
3741 if (!detect_init_independence(m, count)) {
3742 return false;
3743 }
3744 }
3745
3746 return true;
3747 }
3748
3749 // Here are all the checks a Store must pass before it can be moved into
3750 // an initialization. Returns zero if a check fails.
3751 // On success, returns the (constant) offset to which the store applies,
3752 // within the initialized memory.
3753 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3754 const int FAIL = 0;
3755 if (st->req() != MemNode::ValueIn + 1)
3756 return FAIL; // an inscrutable StoreNode (card mark?)
3757 Node* ctl = st->in(MemNode::Control);
3758 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3759 return FAIL; // must be unconditional after the initialization
3760 Node* mem = st->in(MemNode::Memory);
3761 if (!(mem->is_Proj() && mem->in(0) == this))
3762 return FAIL; // must not be preceded by other stores
3763 Node* adr = st->in(MemNode::Address);
3764 intptr_t offset;
3765 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3766 if (alloc == NULL)
3767 return FAIL; // inscrutable address
3768 if (alloc != allocation())
3769 return FAIL; // wrong allocation! (store needs to float up)
3770 int size_in_bytes = st->memory_size();
3771 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3772 return FAIL; // mismatched access
3773 }
3774 Node* val = st->in(MemNode::ValueIn);
3775 int complexity_count = 0;
3776 if (!detect_init_independence(val, complexity_count))
3777 return FAIL; // stored value must be 'simple enough'
3778
3779 // The Store can be captured only if nothing after the allocation
3780 // and before the Store is using the memory location that the store
3781 // overwrites.
3782 bool failed = false;
3783 // If is_complete_with_arraycopy() is true the shape of the graph is
3784 // well defined and is safe so no need for extra checks.
3785 if (!is_complete_with_arraycopy()) {
3786 // We are going to look at each use of the memory state following
3787 // the allocation to make sure nothing reads the memory that the
3788 // Store writes.
3789 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3790 int alias_idx = phase->C->get_alias_index(t_adr);
3791 ResourceMark rm;
3792 Unique_Node_List mems;
3793 mems.push(mem);
3794 Node* unique_merge = NULL;
3795 for (uint next = 0; next < mems.size(); ++next) {
3796 Node *m = mems.at(next);
3797 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3798 Node *n = m->fast_out(j);
3799 if (n->outcnt() == 0) {
3800 continue;
3801 }
3802 if (n == st) {
3803 continue;
3804 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3805 // If the control of this use is different from the control
3806 // of the Store which is right after the InitializeNode then
3807 // this node cannot be between the InitializeNode and the
3808 // Store.
3809 continue;
3810 } else if (n->is_MergeMem()) {
3811 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3812 // We can hit a MergeMemNode (that will likely go away
3813 // later) that is a direct use of the memory state
3814 // following the InitializeNode on the same slice as the
3815 // store node that we'd like to capture. We need to check
3816 // the uses of the MergeMemNode.
3817 mems.push(n);
3818 }
3819 } else if (n->is_Mem()) {
3820 Node* other_adr = n->in(MemNode::Address);
3821 if (other_adr == adr) {
3822 failed = true;
3823 break;
3824 } else {
3825 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3826 if (other_t_adr != NULL) {
3827 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3828 if (other_alias_idx == alias_idx) {
3829 // A load from the same memory slice as the store right
3830 // after the InitializeNode. We check the control of the
3831 // object/array that is loaded from. If it's the same as
3832 // the store control then we cannot capture the store.
3833 assert(!n->is_Store(), "2 stores to same slice on same control?");
3834 Node* base = other_adr;
3835 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3836 base = base->in(AddPNode::Base);
3837 if (base != NULL) {
3838 base = base->uncast();
3839 if (base->is_Proj() && base->in(0) == alloc) {
3840 failed = true;
3841 break;
3842 }
3843 }
3844 }
3845 }
3846 }
3847 } else {
3848 failed = true;
3849 break;
3850 }
3851 }
3852 }
3853 }
3854 if (failed) {
3855 if (!can_reshape) {
3856 // We decided we couldn't capture the store during parsing. We
3857 // should try again during the next IGVN once the graph is
3858 // cleaner.
3859 phase->C->record_for_igvn(st);
3860 }
3861 return FAIL;
3862 }
3863
3864 return offset; // success
3865 }
3866
3867 // Find the captured store in(i) which corresponds to the range
3868 // [start..start+size) in the initialized object.
3869 // If there is one, return its index i. If there isn't, return the
3870 // negative of the index where it should be inserted.
3871 // Return 0 if the queried range overlaps an initialization boundary
3872 // or if dead code is encountered.
3873 // If size_in_bytes is zero, do not bother with overlap checks.
3874 int InitializeNode::captured_store_insertion_point(intptr_t start,
3875 int size_in_bytes,
3876 PhaseTransform* phase) {
3877 const int FAIL = 0, MAX_STORE = BytesPerLong;
3878
3879 if (is_complete())
3880 return FAIL; // arraycopy got here first; punt
3881
3882 assert(allocation() != NULL, "must be present");
3883
3884 // no negatives, no header fields:
3885 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3886
3887 // after a certain size, we bail out on tracking all the stores:
3888 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3889 if (start >= ti_limit) return FAIL;
3890
3891 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3892 if (i >= limit) return -(int)i; // not found; here is where to put it
3893
3894 Node* st = in(i);
3895 intptr_t st_off = get_store_offset(st, phase);
3896 if (st_off < 0) {
3897 if (st != zero_memory()) {
3898 return FAIL; // bail out if there is dead garbage
3899 }
3900 } else if (st_off > start) {
3901 // ...we are done, since stores are ordered
3902 if (st_off < start + size_in_bytes) {
3903 return FAIL; // the next store overlaps
3904 }
3905 return -(int)i; // not found; here is where to put it
3906 } else if (st_off < start) {
3907 if (size_in_bytes != 0 &&
3908 start < st_off + MAX_STORE &&
3909 start < st_off + st->as_Store()->memory_size()) {
3910 return FAIL; // the previous store overlaps
3911 }
3912 } else {
3913 if (size_in_bytes != 0 &&
3914 st->as_Store()->memory_size() != size_in_bytes) {
3915 return FAIL; // mismatched store size
3916 }
3917 return i;
3918 }
3919
3920 ++i;
3921 }
3922 }
3923
3924 // Look for a captured store which initializes at the offset 'start'
3925 // with the given size. If there is no such store, and no other
3926 // initialization interferes, then return zero_memory (the memory
3927 // projection of the AllocateNode).
3928 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3929 PhaseTransform* phase) {
3930 assert(stores_are_sane(phase), "");
3931 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3932 if (i == 0) {
3933 return NULL; // something is dead
3934 } else if (i < 0) {
3935 return zero_memory(); // just primordial zero bits here
3936 } else {
3937 Node* st = in(i); // here is the store at this position
3938 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3939 return st;
3940 }
3941 }
3942
3943 // Create, as a raw pointer, an address within my new object at 'offset'.
3944 Node* InitializeNode::make_raw_address(intptr_t offset,
3945 PhaseTransform* phase) {
3946 Node* addr = in(RawAddress);
3947 if (offset != 0) {
3948 Compile* C = phase->C;
3949 addr = phase->transform( new AddPNode(C->top(), addr,
3950 phase->MakeConX(offset)) );
3951 }
3952 return addr;
3953 }
3954
3955 // Clone the given store, converting it into a raw store
3956 // initializing a field or element of my new object.
3957 // Caller is responsible for retiring the original store,
3958 // with subsume_node or the like.
3959 //
3960 // From the example above InitializeNode::InitializeNode,
3961 // here are the old stores to be captured:
3962 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3963 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3964 //
3965 // Here is the changed code; note the extra edges on init:
3966 // alloc = (Allocate ...)
3967 // rawoop = alloc.RawAddress
3968 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3969 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3970 // init = (Initialize alloc.Control alloc.Memory rawoop
3971 // rawstore1 rawstore2)
3972 //
3973 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3974 PhaseTransform* phase, bool can_reshape) {
3975 assert(stores_are_sane(phase), "");
3976
3977 if (start < 0) return NULL;
3978 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3979
3980 Compile* C = phase->C;
3981 int size_in_bytes = st->memory_size();
3982 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3983 if (i == 0) return NULL; // bail out
3984 Node* prev_mem = NULL; // raw memory for the captured store
3985 if (i > 0) {
3986 prev_mem = in(i); // there is a pre-existing store under this one
3987 set_req(i, C->top()); // temporarily disconnect it
3988 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3989 } else {
3990 i = -i; // no pre-existing store
3991 prev_mem = zero_memory(); // a slice of the newly allocated object
3992 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3993 set_req(--i, C->top()); // reuse this edge; it has been folded away
3994 else
3995 ins_req(i, C->top()); // build a new edge
3996 }
3997 Node* new_st = st->clone();
3998 new_st->set_req(MemNode::Control, in(Control));
3999 new_st->set_req(MemNode::Memory, prev_mem);
4000 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4001 new_st = phase->transform(new_st);
4002
4003 // At this point, new_st might have swallowed a pre-existing store
4004 // at the same offset, or perhaps new_st might have disappeared,
4005 // if it redundantly stored the same value (or zero to fresh memory).
4006
4007 // In any case, wire it in:
4008 phase->igvn_rehash_node_delayed(this);
4009 set_req(i, new_st);
4010
4011 // The caller may now kill the old guy.
4012 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4013 assert(check_st == new_st || check_st == NULL, "must be findable");
4014 assert(!is_complete(), "");
4015 return new_st;
4016 }
4017
4018 static bool store_constant(jlong* tiles, int num_tiles,
4019 intptr_t st_off, int st_size,
4020 jlong con) {
4021 if ((st_off & (st_size-1)) != 0)
4022 return false; // strange store offset (assume size==2**N)
4023 address addr = (address)tiles + st_off;
4024 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4025 switch (st_size) {
4026 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4027 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4028 case sizeof(jint): *(jint*) addr = (jint) con; break;
4029 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4030 default: return false; // strange store size (detect size!=2**N here)
4031 }
4032 return true; // return success to caller
4033 }
4034
4035 // Coalesce subword constants into int constants and possibly
4036 // into long constants. The goal, if the CPU permits,
4037 // is to initialize the object with a small number of 64-bit tiles.
4038 // Also, convert floating-point constants to bit patterns.
4039 // Non-constants are not relevant to this pass.
4040 //
4041 // In terms of the running example on InitializeNode::InitializeNode
4042 // and InitializeNode::capture_store, here is the transformation
4043 // of rawstore1 and rawstore2 into rawstore12:
4044 // alloc = (Allocate ...)
4045 // rawoop = alloc.RawAddress
4046 // tile12 = 0x00010002
4047 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4048 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4049 //
4050 void
4051 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4052 Node* size_in_bytes,
4053 PhaseGVN* phase) {
4054 Compile* C = phase->C;
4055
4056 assert(stores_are_sane(phase), "");
4057 // Note: After this pass, they are not completely sane,
4058 // since there may be some overlaps.
4059
4060 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4061
4062 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4063 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4064 size_limit = MIN2(size_limit, ti_limit);
4065 size_limit = align_up(size_limit, BytesPerLong);
4066 int num_tiles = size_limit / BytesPerLong;
4067
4068 // allocate space for the tile map:
4069 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4070 jlong tiles_buf[small_len];
4071 Node* nodes_buf[small_len];
4072 jlong inits_buf[small_len];
4073 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4074 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4075 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4076 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4077 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4078 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4079 // tiles: exact bitwise model of all primitive constants
4080 // nodes: last constant-storing node subsumed into the tiles model
4081 // inits: which bytes (in each tile) are touched by any initializations
4082
4083 //// Pass A: Fill in the tile model with any relevant stores.
4084
4085 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4086 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4087 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4088 Node* zmem = zero_memory(); // initially zero memory state
4089 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4090 Node* st = in(i);
4091 intptr_t st_off = get_store_offset(st, phase);
4092
4093 // Figure out the store's offset and constant value:
4094 if (st_off < header_size) continue; //skip (ignore header)
4095 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4096 int st_size = st->as_Store()->memory_size();
4097 if (st_off + st_size > size_limit) break;
4098
4099 // Record which bytes are touched, whether by constant or not.
4100 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4101 continue; // skip (strange store size)
4102
4103 const Type* val = phase->type(st->in(MemNode::ValueIn));
4104 if (!val->singleton()) continue; //skip (non-con store)
4105 BasicType type = val->basic_type();
4106
4107 jlong con = 0;
4108 switch (type) {
4109 case T_INT: con = val->is_int()->get_con(); break;
4110 case T_LONG: con = val->is_long()->get_con(); break;
4111 case T_FLOAT: con = jint_cast(val->getf()); break;
4112 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4113 default: continue; //skip (odd store type)
4114 }
4115
4116 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4117 st->Opcode() == Op_StoreL) {
4118 continue; // This StoreL is already optimal.
4119 }
4120
4121 // Store down the constant.
4122 store_constant(tiles, num_tiles, st_off, st_size, con);
4123
4124 intptr_t j = st_off >> LogBytesPerLong;
4125
4126 if (type == T_INT && st_size == BytesPerInt
4127 && (st_off & BytesPerInt) == BytesPerInt) {
4128 jlong lcon = tiles[j];
4129 if (!Matcher::isSimpleConstant64(lcon) &&
4130 st->Opcode() == Op_StoreI) {
4131 // This StoreI is already optimal by itself.
4132 jint* intcon = (jint*) &tiles[j];
4133 intcon[1] = 0; // undo the store_constant()
4134
4135 // If the previous store is also optimal by itself, back up and
4136 // undo the action of the previous loop iteration... if we can.
4137 // But if we can't, just let the previous half take care of itself.
4138 st = nodes[j];
4139 st_off -= BytesPerInt;
4140 con = intcon[0];
4141 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4142 assert(st_off >= header_size, "still ignoring header");
4143 assert(get_store_offset(st, phase) == st_off, "must be");
4144 assert(in(i-1) == zmem, "must be");
4145 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4146 assert(con == tcon->is_int()->get_con(), "must be");
4147 // Undo the effects of the previous loop trip, which swallowed st:
4148 intcon[0] = 0; // undo store_constant()
4149 set_req(i-1, st); // undo set_req(i, zmem)
4150 nodes[j] = NULL; // undo nodes[j] = st
4151 --old_subword; // undo ++old_subword
4152 }
4153 continue; // This StoreI is already optimal.
4154 }
4155 }
4156
4157 // This store is not needed.
4158 set_req(i, zmem);
4159 nodes[j] = st; // record for the moment
4160 if (st_size < BytesPerLong) // something has changed
4161 ++old_subword; // includes int/float, but who's counting...
4162 else ++old_long;
4163 }
4164
4165 if ((old_subword + old_long) == 0)
4166 return; // nothing more to do
4167
4168 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4169 // Be sure to insert them before overlapping non-constant stores.
4170 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4171 for (int j = 0; j < num_tiles; j++) {
4172 jlong con = tiles[j];
4173 jlong init = inits[j];
4174 if (con == 0) continue;
4175 jint con0, con1; // split the constant, address-wise
4176 jint init0, init1; // split the init map, address-wise
4177 { union { jlong con; jint intcon[2]; } u;
4178 u.con = con;
4179 con0 = u.intcon[0];
4180 con1 = u.intcon[1];
4181 u.con = init;
4182 init0 = u.intcon[0];
4183 init1 = u.intcon[1];
4184 }
4185
4186 Node* old = nodes[j];
4187 assert(old != NULL, "need the prior store");
4188 intptr_t offset = (j * BytesPerLong);
4189
4190 bool split = !Matcher::isSimpleConstant64(con);
4191
4192 if (offset < header_size) {
4193 assert(offset + BytesPerInt >= header_size, "second int counts");
4194 assert(*(jint*)&tiles[j] == 0, "junk in header");
4195 split = true; // only the second word counts
4196 // Example: int a[] = { 42 ... }
4197 } else if (con0 == 0 && init0 == -1) {
4198 split = true; // first word is covered by full inits
4199 // Example: int a[] = { ... foo(), 42 ... }
4200 } else if (con1 == 0 && init1 == -1) {
4201 split = true; // second word is covered by full inits
4202 // Example: int a[] = { ... 42, foo() ... }
4203 }
4204
4205 // Here's a case where init0 is neither 0 nor -1:
4206 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4207 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4208 // In this case the tile is not split; it is (jlong)42.
4209 // The big tile is stored down, and then the foo() value is inserted.
4210 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4211
4212 Node* ctl = old->in(MemNode::Control);
4213 Node* adr = make_raw_address(offset, phase);
4214 const TypePtr* atp = TypeRawPtr::BOTTOM;
4215
4216 // One or two coalesced stores to plop down.
4217 Node* st[2];
4218 intptr_t off[2];
4219 int nst = 0;
4220 if (!split) {
4221 ++new_long;
4222 off[nst] = offset;
4223 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4224 phase->longcon(con), T_LONG, MemNode::unordered);
4225 } else {
4226 // Omit either if it is a zero.
4227 if (con0 != 0) {
4228 ++new_int;
4229 off[nst] = offset;
4230 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4231 phase->intcon(con0), T_INT, MemNode::unordered);
4232 }
4233 if (con1 != 0) {
4234 ++new_int;
4235 offset += BytesPerInt;
4236 adr = make_raw_address(offset, phase);
4237 off[nst] = offset;
4238 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4239 phase->intcon(con1), T_INT, MemNode::unordered);
4240 }
4241 }
4242
4243 // Insert second store first, then the first before the second.
4244 // Insert each one just before any overlapping non-constant stores.
4245 while (nst > 0) {
4246 Node* st1 = st[--nst];
4247 C->copy_node_notes_to(st1, old);
4248 st1 = phase->transform(st1);
4249 offset = off[nst];
4250 assert(offset >= header_size, "do not smash header");
4251 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4252 guarantee(ins_idx != 0, "must re-insert constant store");
4253 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4254 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4255 set_req(--ins_idx, st1);
4256 else
4257 ins_req(ins_idx, st1);
4258 }
4259 }
4260
4261 if (PrintCompilation && WizardMode)
4262 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4263 old_subword, old_long, new_int, new_long);
4264 if (C->log() != NULL)
4265 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4266 old_subword, old_long, new_int, new_long);
4267
4268 // Clean up any remaining occurrences of zmem:
4269 remove_extra_zeroes();
4270 }
4271
4272 // Explore forward from in(start) to find the first fully initialized
4273 // word, and return its offset. Skip groups of subword stores which
4274 // together initialize full words. If in(start) is itself part of a
4275 // fully initialized word, return the offset of in(start). If there
4276 // are no following full-word stores, or if something is fishy, return
4277 // a negative value.
4278 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4279 int int_map = 0;
4280 intptr_t int_map_off = 0;
4281 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4282
4283 for (uint i = start, limit = req(); i < limit; i++) {
4284 Node* st = in(i);
4285
4286 intptr_t st_off = get_store_offset(st, phase);
4287 if (st_off < 0) break; // return conservative answer
4288
4289 int st_size = st->as_Store()->memory_size();
4290 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4291 return st_off; // we found a complete word init
4292 }
4293
4294 // update the map:
4295
4296 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4297 if (this_int_off != int_map_off) {
4298 // reset the map:
4299 int_map = 0;
4300 int_map_off = this_int_off;
4301 }
4302
4303 int subword_off = st_off - this_int_off;
4304 int_map |= right_n_bits(st_size) << subword_off;
4305 if ((int_map & FULL_MAP) == FULL_MAP) {
4306 return this_int_off; // we found a complete word init
4307 }
4308
4309 // Did this store hit or cross the word boundary?
4310 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4311 if (next_int_off == this_int_off + BytesPerInt) {
4312 // We passed the current int, without fully initializing it.
4313 int_map_off = next_int_off;
4314 int_map >>= BytesPerInt;
4315 } else if (next_int_off > this_int_off + BytesPerInt) {
4316 // We passed the current and next int.
4317 return this_int_off + BytesPerInt;
4318 }
4319 }
4320
4321 return -1;
4322 }
4323
4324
4325 // Called when the associated AllocateNode is expanded into CFG.
4326 // At this point, we may perform additional optimizations.
4327 // Linearize the stores by ascending offset, to make memory
4328 // activity as coherent as possible.
4329 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4330 intptr_t header_size,
4331 Node* size_in_bytes,
4332 PhaseGVN* phase) {
4333 assert(!is_complete(), "not already complete");
4334 assert(stores_are_sane(phase), "");
4335 assert(allocation() != NULL, "must be present");
4336
4337 remove_extra_zeroes();
4338
4339 if (ReduceFieldZeroing || ReduceBulkZeroing)
4340 // reduce instruction count for common initialization patterns
4341 coalesce_subword_stores(header_size, size_in_bytes, phase);
4342
4343 Node* zmem = zero_memory(); // initially zero memory state
4344 Node* inits = zmem; // accumulating a linearized chain of inits
4345 #ifdef ASSERT
4346 intptr_t first_offset = allocation()->minimum_header_size();
4347 intptr_t last_init_off = first_offset; // previous init offset
4348 intptr_t last_init_end = first_offset; // previous init offset+size
4349 intptr_t last_tile_end = first_offset; // previous tile offset+size
4350 #endif
4351 intptr_t zeroes_done = header_size;
4352
4353 bool do_zeroing = true; // we might give up if inits are very sparse
4354 int big_init_gaps = 0; // how many large gaps have we seen?
4355
4356 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4357 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4358
4359 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4360 Node* st = in(i);
4361 intptr_t st_off = get_store_offset(st, phase);
4362 if (st_off < 0)
4363 break; // unknown junk in the inits
4364 if (st->in(MemNode::Memory) != zmem)
4365 break; // complicated store chains somehow in list
4366
4367 int st_size = st->as_Store()->memory_size();
4368 intptr_t next_init_off = st_off + st_size;
4369
4370 if (do_zeroing && zeroes_done < next_init_off) {
4371 // See if this store needs a zero before it or under it.
4372 intptr_t zeroes_needed = st_off;
4373
4374 if (st_size < BytesPerInt) {
4375 // Look for subword stores which only partially initialize words.
4376 // If we find some, we must lay down some word-level zeroes first,
4377 // underneath the subword stores.
4378 //
4379 // Examples:
4380 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4381 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4382 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4383 //
4384 // Note: coalesce_subword_stores may have already done this,
4385 // if it was prompted by constant non-zero subword initializers.
4386 // But this case can still arise with non-constant stores.
4387
4388 intptr_t next_full_store = find_next_fullword_store(i, phase);
4389
4390 // In the examples above:
4391 // in(i) p q r s x y z
4392 // st_off 12 13 14 15 12 13 14
4393 // st_size 1 1 1 1 1 1 1
4394 // next_full_s. 12 16 16 16 16 16 16
4395 // z's_done 12 16 16 16 12 16 12
4396 // z's_needed 12 16 16 16 16 16 16
4397 // zsize 0 0 0 0 4 0 4
4398 if (next_full_store < 0) {
4399 // Conservative tack: Zero to end of current word.
4400 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4401 } else {
4402 // Zero to beginning of next fully initialized word.
4403 // Or, don't zero at all, if we are already in that word.
4404 assert(next_full_store >= zeroes_needed, "must go forward");
4405 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4406 zeroes_needed = next_full_store;
4407 }
4408 }
4409
4410 if (zeroes_needed > zeroes_done) {
4411 intptr_t zsize = zeroes_needed - zeroes_done;
4412 // Do some incremental zeroing on rawmem, in parallel with inits.
4413 zeroes_done = align_down(zeroes_done, BytesPerInt);
4414 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4415 allocation()->in(AllocateNode::DefaultValue),
4416 allocation()->in(AllocateNode::RawDefaultValue),
4417 zeroes_done, zeroes_needed,
4418 phase);
4419 zeroes_done = zeroes_needed;
4420 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4421 do_zeroing = false; // leave the hole, next time
4422 }
4423 }
4424
4425 // Collect the store and move on:
4426 st->set_req(MemNode::Memory, inits);
4427 inits = st; // put it on the linearized chain
4428 set_req(i, zmem); // unhook from previous position
4429
4430 if (zeroes_done == st_off)
4431 zeroes_done = next_init_off;
4432
4433 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4434
4435 #ifdef ASSERT
4436 // Various order invariants. Weaker than stores_are_sane because
4437 // a large constant tile can be filled in by smaller non-constant stores.
4438 assert(st_off >= last_init_off, "inits do not reverse");
4439 last_init_off = st_off;
4440 const Type* val = NULL;
4441 if (st_size >= BytesPerInt &&
4442 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4443 (int)val->basic_type() < (int)T_OBJECT) {
4444 assert(st_off >= last_tile_end, "tiles do not overlap");
4445 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4446 last_tile_end = MAX2(last_tile_end, next_init_off);
4447 } else {
4448 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4449 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4450 assert(st_off >= last_init_end, "inits do not overlap");
4451 last_init_end = next_init_off; // it's a non-tile
4452 }
4453 #endif //ASSERT
4454 }
4455
4456 remove_extra_zeroes(); // clear out all the zmems left over
4457 add_req(inits);
4458
4459 if (!(UseTLAB && ZeroTLAB)) {
4460 // If anything remains to be zeroed, zero it all now.
4461 zeroes_done = align_down(zeroes_done, BytesPerInt);
4462 // if it is the last unused 4 bytes of an instance, forget about it
4463 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4464 if (zeroes_done + BytesPerLong >= size_limit) {
4465 AllocateNode* alloc = allocation();
4466 assert(alloc != NULL, "must be present");
4467 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4468 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4469 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4470 if (zeroes_done == k->layout_helper())
4471 zeroes_done = size_limit;
4472 }
4473 }
4474 if (zeroes_done < size_limit) {
4475 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4476 allocation()->in(AllocateNode::DefaultValue),
4477 allocation()->in(AllocateNode::RawDefaultValue),
4478 zeroes_done, size_in_bytes, phase);
4479 }
4480 }
4481
4482 set_complete(phase);
4483 return rawmem;
4484 }
4485
4486
4487 #ifdef ASSERT
4488 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4489 if (is_complete())
4490 return true; // stores could be anything at this point
4491 assert(allocation() != NULL, "must be present");
4492 intptr_t last_off = allocation()->minimum_header_size();
4493 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4494 Node* st = in(i);
4495 intptr_t st_off = get_store_offset(st, phase);
4496 if (st_off < 0) continue; // ignore dead garbage
4497 if (last_off > st_off) {
4498 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4499 this->dump(2);
4500 assert(false, "ascending store offsets");
4501 return false;
4502 }
4503 last_off = st_off + st->as_Store()->memory_size();
4504 }
4505 return true;
4506 }
4507 #endif //ASSERT
4508
4509
4510
4511
4512 //============================MergeMemNode=====================================
4513 //
4514 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4515 // contributing store or call operations. Each contributor provides the memory
4516 // state for a particular "alias type" (see Compile::alias_type). For example,
4517 // if a MergeMem has an input X for alias category #6, then any memory reference
4518 // to alias category #6 may use X as its memory state input, as an exact equivalent
4519 // to using the MergeMem as a whole.
4520 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4521 //
4522 // (Here, the <N> notation gives the index of the relevant adr_type.)
4523 //
4524 // In one special case (and more cases in the future), alias categories overlap.
4525 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4526 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4527 // it is exactly equivalent to that state W:
4528 // MergeMem(<Bot>: W) <==> W
4529 //
4530 // Usually, the merge has more than one input. In that case, where inputs
4531 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4532 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4533 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4534 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4535 //
4536 // A merge can take a "wide" memory state as one of its narrow inputs.
4537 // This simply means that the merge observes out only the relevant parts of
4538 // the wide input. That is, wide memory states arriving at narrow merge inputs
4539 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4540 //
4541 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4542 // and that memory slices "leak through":
4543 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4544 //
4545 // But, in such a cascade, repeated memory slices can "block the leak":
4546 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4547 //
4548 // In the last example, Y is not part of the combined memory state of the
4549 // outermost MergeMem. The system must, of course, prevent unschedulable
4550 // memory states from arising, so you can be sure that the state Y is somehow
4551 // a precursor to state Y'.
4552 //
4553 //
4554 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4555 // of each MergeMemNode array are exactly the numerical alias indexes, including
4556 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4557 // Compile::alias_type (and kin) produce and manage these indexes.
4558 //
4559 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4560 // (Note that this provides quick access to the top node inside MergeMem methods,
4561 // without the need to reach out via TLS to Compile::current.)
4562 //
4563 // As a consequence of what was just described, a MergeMem that represents a full
4564 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4565 // containing all alias categories.
4566 //
4567 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4568 //
4569 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4570 // a memory state for the alias type <N>, or else the top node, meaning that
4571 // there is no particular input for that alias type. Note that the length of
4572 // a MergeMem is variable, and may be extended at any time to accommodate new
4573 // memory states at larger alias indexes. When merges grow, they are of course
4574 // filled with "top" in the unused in() positions.
4575 //
4576 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4577 // (Top was chosen because it works smoothly with passes like GCM.)
4578 //
4579 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4580 // the type of random VM bits like TLS references.) Since it is always the
4581 // first non-Bot memory slice, some low-level loops use it to initialize an
4582 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4583 //
4584 //
4585 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4586 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4587 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4588 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4589 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4590 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4591 //
4592 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4593 // really that different from the other memory inputs. An abbreviation called
4594 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4595 //
4596 //
4597 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4598 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4599 // that "emerges though" the base memory will be marked as excluding the alias types
4600 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4601 //
4602 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4603 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4604 //
4605 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4606 // (It is currently unimplemented.) As you can see, the resulting merge is
4607 // actually a disjoint union of memory states, rather than an overlay.
4608 //
4609
4610 //------------------------------MergeMemNode-----------------------------------
4611 Node* MergeMemNode::make_empty_memory() {
4612 Node* empty_memory = (Node*) Compile::current()->top();
4613 assert(empty_memory->is_top(), "correct sentinel identity");
4614 return empty_memory;
4615 }
4616
4617 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4618 init_class_id(Class_MergeMem);
4619 // all inputs are nullified in Node::Node(int)
4620 // set_input(0, NULL); // no control input
4621
4622 // Initialize the edges uniformly to top, for starters.
4623 Node* empty_mem = make_empty_memory();
4624 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4625 init_req(i,empty_mem);
4626 }
4627 assert(empty_memory() == empty_mem, "");
4628
4629 if( new_base != NULL && new_base->is_MergeMem() ) {
4630 MergeMemNode* mdef = new_base->as_MergeMem();
4631 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4632 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4633 mms.set_memory(mms.memory2());
4634 }
4635 assert(base_memory() == mdef->base_memory(), "");
4636 } else {
4637 set_base_memory(new_base);
4638 }
4639 }
4640
4641 // Make a new, untransformed MergeMem with the same base as 'mem'.
4642 // If mem is itself a MergeMem, populate the result with the same edges.
4643 MergeMemNode* MergeMemNode::make(Node* mem) {
4644 return new MergeMemNode(mem);
4645 }
4646
4647 //------------------------------cmp--------------------------------------------
4648 uint MergeMemNode::hash() const { return NO_HASH; }
4649 bool MergeMemNode::cmp( const Node &n ) const {
4650 return (&n == this); // Always fail except on self
4651 }
4652
4653 //------------------------------Identity---------------------------------------
4654 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4655 // Identity if this merge point does not record any interesting memory
4656 // disambiguations.
4657 Node* base_mem = base_memory();
4658 Node* empty_mem = empty_memory();
4659 if (base_mem != empty_mem) { // Memory path is not dead?
4660 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4661 Node* mem = in(i);
4662 if (mem != empty_mem && mem != base_mem) {
4663 return this; // Many memory splits; no change
4664 }
4665 }
4666 }
4667 return base_mem; // No memory splits; ID on the one true input
4668 }
4669
4670 //------------------------------Ideal------------------------------------------
4671 // This method is invoked recursively on chains of MergeMem nodes
4672 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4673 // Remove chain'd MergeMems
4674 //
4675 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4676 // relative to the "in(Bot)". Since we are patching both at the same time,
4677 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4678 // but rewrite each "in(i)" relative to the new "in(Bot)".
4679 Node *progress = NULL;
4680
4681
4682 Node* old_base = base_memory();
4683 Node* empty_mem = empty_memory();
4684 if (old_base == empty_mem)
4685 return NULL; // Dead memory path.
4686
4687 MergeMemNode* old_mbase;
4688 if (old_base != NULL && old_base->is_MergeMem())
4689 old_mbase = old_base->as_MergeMem();
4690 else
4691 old_mbase = NULL;
4692 Node* new_base = old_base;
4693
4694 // simplify stacked MergeMems in base memory
4695 if (old_mbase) new_base = old_mbase->base_memory();
4696
4697 // the base memory might contribute new slices beyond my req()
4698 if (old_mbase) grow_to_match(old_mbase);
4699
4700 // Look carefully at the base node if it is a phi.
4701 PhiNode* phi_base;
4702 if (new_base != NULL && new_base->is_Phi())
4703 phi_base = new_base->as_Phi();
4704 else
4705 phi_base = NULL;
4706
4707 Node* phi_reg = NULL;
4708 uint phi_len = (uint)-1;
4709 if (phi_base != NULL && !phi_base->is_copy()) {
4710 // do not examine phi if degraded to a copy
4711 phi_reg = phi_base->region();
4712 phi_len = phi_base->req();
4713 // see if the phi is unfinished
4714 for (uint i = 1; i < phi_len; i++) {
4715 if (phi_base->in(i) == NULL) {
4716 // incomplete phi; do not look at it yet!
4717 phi_reg = NULL;
4718 phi_len = (uint)-1;
4719 break;
4720 }
4721 }
4722 }
4723
4724 // Note: We do not call verify_sparse on entry, because inputs
4725 // can normalize to the base_memory via subsume_node or similar
4726 // mechanisms. This method repairs that damage.
4727
4728 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4729
4730 // Look at each slice.
4731 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4732 Node* old_in = in(i);
4733 // calculate the old memory value
4734 Node* old_mem = old_in;
4735 if (old_mem == empty_mem) old_mem = old_base;
4736 assert(old_mem == memory_at(i), "");
4737
4738 // maybe update (reslice) the old memory value
4739
4740 // simplify stacked MergeMems
4741 Node* new_mem = old_mem;
4742 MergeMemNode* old_mmem;
4743 if (old_mem != NULL && old_mem->is_MergeMem())
4744 old_mmem = old_mem->as_MergeMem();
4745 else
4746 old_mmem = NULL;
4747 if (old_mmem == this) {
4748 // This can happen if loops break up and safepoints disappear.
4749 // A merge of BotPtr (default) with a RawPtr memory derived from a
4750 // safepoint can be rewritten to a merge of the same BotPtr with
4751 // the BotPtr phi coming into the loop. If that phi disappears
4752 // also, we can end up with a self-loop of the mergemem.
4753 // In general, if loops degenerate and memory effects disappear,
4754 // a mergemem can be left looking at itself. This simply means
4755 // that the mergemem's default should be used, since there is
4756 // no longer any apparent effect on this slice.
4757 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4758 // from start. Update the input to TOP.
4759 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4760 }
4761 else if (old_mmem != NULL) {
4762 new_mem = old_mmem->memory_at(i);
4763 }
4764 // else preceding memory was not a MergeMem
4765
4766 // replace equivalent phis (unfortunately, they do not GVN together)
4767 if (new_mem != NULL && new_mem != new_base &&
4768 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4769 if (new_mem->is_Phi()) {
4770 PhiNode* phi_mem = new_mem->as_Phi();
4771 for (uint i = 1; i < phi_len; i++) {
4772 if (phi_base->in(i) != phi_mem->in(i)) {
4773 phi_mem = NULL;
4774 break;
4775 }
4776 }
4777 if (phi_mem != NULL) {
4778 // equivalent phi nodes; revert to the def
4779 new_mem = new_base;
4780 }
4781 }
4782 }
4783
4784 // maybe store down a new value
4785 Node* new_in = new_mem;
4786 if (new_in == new_base) new_in = empty_mem;
4787
4788 if (new_in != old_in) {
4789 // Warning: Do not combine this "if" with the previous "if"
4790 // A memory slice might have be be rewritten even if it is semantically
4791 // unchanged, if the base_memory value has changed.
4792 set_req(i, new_in);
4793 progress = this; // Report progress
4794 }
4795 }
4796
4797 if (new_base != old_base) {
4798 set_req(Compile::AliasIdxBot, new_base);
4799 // Don't use set_base_memory(new_base), because we need to update du.
4800 assert(base_memory() == new_base, "");
4801 progress = this;
4802 }
4803
4804 if( base_memory() == this ) {
4805 // a self cycle indicates this memory path is dead
4806 set_req(Compile::AliasIdxBot, empty_mem);
4807 }
4808
4809 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4810 // Recursion must occur after the self cycle check above
4811 if( base_memory()->is_MergeMem() ) {
4812 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4813 Node *m = phase->transform(new_mbase); // Rollup any cycles
4814 if( m != NULL &&
4815 (m->is_top() ||
4816 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4817 // propagate rollup of dead cycle to self
4818 set_req(Compile::AliasIdxBot, empty_mem);
4819 }
4820 }
4821
4822 if( base_memory() == empty_mem ) {
4823 progress = this;
4824 // Cut inputs during Parse phase only.
4825 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4826 if( !can_reshape ) {
4827 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4828 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4829 }
4830 }
4831 }
4832
4833 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4834 // Check if PhiNode::Ideal's "Split phis through memory merges"
4835 // transform should be attempted. Look for this->phi->this cycle.
4836 uint merge_width = req();
4837 if (merge_width > Compile::AliasIdxRaw) {
4838 PhiNode* phi = base_memory()->as_Phi();
4839 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4840 if (phi->in(i) == this) {
4841 phase->is_IterGVN()->_worklist.push(phi);
4842 break;
4843 }
4844 }
4845 }
4846 }
4847
4848 assert(progress || verify_sparse(), "please, no dups of base");
4849 return progress;
4850 }
4851
4852 //-------------------------set_base_memory-------------------------------------
4853 void MergeMemNode::set_base_memory(Node *new_base) {
4854 Node* empty_mem = empty_memory();
4855 set_req(Compile::AliasIdxBot, new_base);
4856 assert(memory_at(req()) == new_base, "must set default memory");
4857 // Clear out other occurrences of new_base:
4858 if (new_base != empty_mem) {
4859 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4860 if (in(i) == new_base) set_req(i, empty_mem);
4861 }
4862 }
4863 }
4864
4865 //------------------------------out_RegMask------------------------------------
4866 const RegMask &MergeMemNode::out_RegMask() const {
4867 return RegMask::Empty;
4868 }
4869
4870 //------------------------------dump_spec--------------------------------------
4871 #ifndef PRODUCT
4872 void MergeMemNode::dump_spec(outputStream *st) const {
4873 st->print(" {");
4874 Node* base_mem = base_memory();
4875 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4876 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4877 if (mem == base_mem) { st->print(" -"); continue; }
4878 st->print( " N%d:", mem->_idx );
4879 Compile::current()->get_adr_type(i)->dump_on(st);
4880 }
4881 st->print(" }");
4882 }
4883 #endif // !PRODUCT
4884
4885
4886 #ifdef ASSERT
4887 static bool might_be_same(Node* a, Node* b) {
4888 if (a == b) return true;
4889 if (!(a->is_Phi() || b->is_Phi())) return false;
4890 // phis shift around during optimization
4891 return true; // pretty stupid...
4892 }
4893
4894 // verify a narrow slice (either incoming or outgoing)
4895 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4896 if (!VerifyAliases) return; // don't bother to verify unless requested
4897 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4898 if (Node::in_dump()) return; // muzzle asserts when printing
4899 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4900 assert(n != NULL, "");
4901 // Elide intervening MergeMem's
4902 while (n->is_MergeMem()) {
4903 n = n->as_MergeMem()->memory_at(alias_idx);
4904 }
4905 Compile* C = Compile::current();
4906 const TypePtr* n_adr_type = n->adr_type();
4907 if (n == m->empty_memory()) {
4908 // Implicit copy of base_memory()
4909 } else if (n_adr_type != TypePtr::BOTTOM) {
4910 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4911 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4912 } else {
4913 // A few places like make_runtime_call "know" that VM calls are narrow,
4914 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4915 bool expected_wide_mem = false;
4916 if (n == m->base_memory()) {
4917 expected_wide_mem = true;
4918 } else if (alias_idx == Compile::AliasIdxRaw ||
4919 n == m->memory_at(Compile::AliasIdxRaw)) {
4920 expected_wide_mem = true;
4921 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4922 // memory can "leak through" calls on channels that
4923 // are write-once. Allow this also.
4924 expected_wide_mem = true;
4925 }
4926 assert(expected_wide_mem, "expected narrow slice replacement");
4927 }
4928 }
4929 #else // !ASSERT
4930 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4931 #endif
4932
4933
4934 //-----------------------------memory_at---------------------------------------
4935 Node* MergeMemNode::memory_at(uint alias_idx) const {
4936 assert(alias_idx >= Compile::AliasIdxRaw ||
4937 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4938 "must avoid base_memory and AliasIdxTop");
4939
4940 // Otherwise, it is a narrow slice.
4941 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4942 Compile *C = Compile::current();
4943 if (is_empty_memory(n)) {
4944 // the array is sparse; empty slots are the "top" node
4945 n = base_memory();
4946 assert(Node::in_dump()
4947 || n == NULL || n->bottom_type() == Type::TOP
4948 || n->adr_type() == NULL // address is TOP
4949 || n->adr_type() == TypePtr::BOTTOM
4950 || n->adr_type() == TypeRawPtr::BOTTOM
4951 || Compile::current()->AliasLevel() == 0,
4952 "must be a wide memory");
4953 // AliasLevel == 0 if we are organizing the memory states manually.
4954 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4955 } else {
4956 // make sure the stored slice is sane
4957 #ifdef ASSERT
4958 if (VMError::is_error_reported() || Node::in_dump()) {
4959 } else if (might_be_same(n, base_memory())) {
4960 // Give it a pass: It is a mostly harmless repetition of the base.
4961 // This can arise normally from node subsumption during optimization.
4962 } else {
4963 verify_memory_slice(this, alias_idx, n);
4964 }
4965 #endif
4966 }
4967 return n;
4968 }
4969
4970 //---------------------------set_memory_at-------------------------------------
4971 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4972 verify_memory_slice(this, alias_idx, n);
4973 Node* empty_mem = empty_memory();
4974 if (n == base_memory()) n = empty_mem; // collapse default
4975 uint need_req = alias_idx+1;
4976 if (req() < need_req) {
4977 if (n == empty_mem) return; // already the default, so do not grow me
4978 // grow the sparse array
4979 do {
4980 add_req(empty_mem);
4981 } while (req() < need_req);
4982 }
4983 set_req( alias_idx, n );
4984 }
4985
4986
4987
4988 //--------------------------iteration_setup------------------------------------
4989 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4990 if (other != NULL) {
4991 grow_to_match(other);
4992 // invariant: the finite support of mm2 is within mm->req()
4993 #ifdef ASSERT
4994 for (uint i = req(); i < other->req(); i++) {
4995 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4996 }
4997 #endif
4998 }
4999 // Replace spurious copies of base_memory by top.
5000 Node* base_mem = base_memory();
5001 if (base_mem != NULL && !base_mem->is_top()) {
5002 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5003 if (in(i) == base_mem)
5004 set_req(i, empty_memory());
5005 }
5006 }
5007 }
5008
5009 //---------------------------grow_to_match-------------------------------------
5010 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5011 Node* empty_mem = empty_memory();
5012 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5013 // look for the finite support of the other memory
5014 for (uint i = other->req(); --i >= req(); ) {
5015 if (other->in(i) != empty_mem) {
5016 uint new_len = i+1;
5017 while (req() < new_len) add_req(empty_mem);
5018 break;
5019 }
5020 }
5021 }
5022
5023 //---------------------------verify_sparse-------------------------------------
5024 #ifndef PRODUCT
5025 bool MergeMemNode::verify_sparse() const {
5026 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5027 Node* base_mem = base_memory();
5028 // The following can happen in degenerate cases, since empty==top.
5029 if (is_empty_memory(base_mem)) return true;
5030 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5031 assert(in(i) != NULL, "sane slice");
5032 if (in(i) == base_mem) return false; // should have been the sentinel value!
5033 }
5034 return true;
5035 }
5036
5037 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5038 Node* n;
5039 n = mm->in(idx);
5040 if (mem == n) return true; // might be empty_memory()
5041 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5042 if (mem == n) return true;
5043 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
5044 if (mem == n) return true;
5045 if (n == NULL) break;
5046 }
5047 return false;
5048 }
5049 #endif // !PRODUCT