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
54 // Portions of code courtesy of Clifford Click
55
56 // Optimization - Graph Style
57
58 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
59
60 //=============================================================================
61 uint MemNode::size_of() const { return sizeof(*this); }
62
63 const TypePtr *MemNode::adr_type() const {
64 Node* adr = in(Address);
65 if (adr == NULL) return NULL; // node is dead
66 const TypePtr* cross_check = NULL;
67 DEBUG_ONLY(cross_check = _adr_type);
68 return calculate_adr_type(adr->bottom_type(), cross_check);
69 }
70
71 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
72 if (adr != NULL) {
73 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
74 return true;
75 }
76 }
77 return false;
78 }
79
80 #ifndef PRODUCT
81 void MemNode::dump_spec(outputStream *st) const {
82 if (in(Address) == NULL) return; // node is dead
83 #ifndef ASSERT
84 // fake the missing field
85 const TypePtr* _adr_type = NULL;
86 if (in(Address) != NULL)
87 _adr_type = in(Address)->bottom_type()->isa_ptr();
88 #endif
89 dump_adr_type(this, _adr_type, st);
90
91 Compile* C = Compile::current();
92 if (C->alias_type(_adr_type)->is_volatile()) {
93 st->print(" Volatile!");
94 }
95 if (_unaligned_access) {
96 st->print(" unaligned");
97 }
98 if (_mismatched_access) {
99 st->print(" mismatched");
100 }
101 if (_unsafe_access) {
102 st->print(" unsafe");
103 }
104 }
105
106 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
107 st->print(" @");
108 if (adr_type == NULL) {
109 st->print("NULL");
110 } else {
111 adr_type->dump_on(st);
112 Compile* C = Compile::current();
113 Compile::AliasType* atp = NULL;
114 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
115 if (atp == NULL)
116 st->print(", idx=?\?;");
117 else if (atp->index() == Compile::AliasIdxBot)
118 st->print(", idx=Bot;");
119 else if (atp->index() == Compile::AliasIdxTop)
120 st->print(", idx=Top;");
121 else if (atp->index() == Compile::AliasIdxRaw)
122 st->print(", idx=Raw;");
123 else {
124 ciField* field = atp->field();
125 if (field) {
126 st->print(", name=");
127 field->print_name_on(st);
128 }
129 st->print(", idx=%d;", atp->index());
130 }
131 }
132 }
133
134 extern void print_alias_types();
135
136 #endif
137
138 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
139 assert((t_oop != NULL), "sanity");
140 bool is_instance = t_oop->is_known_instance_field();
141 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
142 (load != NULL) && load->is_Load() &&
143 (phase->is_IterGVN() != NULL);
144 if (!(is_instance || is_boxed_value_load))
145 return mchain; // don't try to optimize non-instance types
146 uint instance_id = t_oop->instance_id();
147 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
148 Node *prev = NULL;
149 Node *result = mchain;
150 while (prev != result) {
151 prev = result;
152 if (result == start_mem)
153 break; // hit one of our sentinels
154 // skip over a call which does not affect this memory slice
155 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
156 Node *proj_in = result->in(0);
157 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
158 break; // hit one of our sentinels
159 } else if (proj_in->is_Call()) {
160 // ArrayCopyNodes processed here as well
161 CallNode *call = proj_in->as_Call();
162 if (!call->may_modify(t_oop, phase)) { // returns false for instances
163 result = call->in(TypeFunc::Memory);
164 }
165 } else if (proj_in->is_Initialize()) {
166 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
167 // Stop if this is the initialization for the object instance which
168 // contains this memory slice, otherwise skip over it.
169 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
170 break;
171 }
172 if (is_instance) {
173 result = proj_in->in(TypeFunc::Memory);
174 } else if (is_boxed_value_load) {
175 Node* klass = alloc->in(AllocateNode::KlassNode);
176 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
177 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
178 result = proj_in->in(TypeFunc::Memory); // not related allocation
179 }
180 }
181 } else if (proj_in->is_MemBar()) {
182 ArrayCopyNode* ac = NULL;
183 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
184 break;
185 }
186 result = proj_in->in(TypeFunc::Memory);
187 } else {
188 assert(false, "unexpected projection");
189 }
190 } else if (result->is_ClearArray()) {
191 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
192 // Can not bypass initialization of the instance
193 // we are looking for.
194 break;
195 }
196 // Otherwise skip it (the call updated 'result' value).
197 } else if (result->is_MergeMem()) {
198 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
199 }
200 }
201 return result;
202 }
203
204 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
205 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
206 if (t_oop == NULL)
207 return mchain; // don't try to optimize non-oop types
208 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
209 bool is_instance = t_oop->is_known_instance_field();
210 PhaseIterGVN *igvn = phase->is_IterGVN();
211 if (is_instance && igvn != NULL && result->is_Phi()) {
212 PhiNode *mphi = result->as_Phi();
213 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
214 const TypePtr *t = mphi->adr_type();
215 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
216 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
217 t->is_oopptr()->cast_to_exactness(true)
218 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
219 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
220 // clone the Phi with our address type
221 result = mphi->split_out_instance(t_adr, igvn);
222 } else {
223 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
224 }
225 }
226 return result;
227 }
228
229 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
230 uint alias_idx = phase->C->get_alias_index(tp);
231 Node *mem = mmem;
232 #ifdef ASSERT
233 {
234 // Check that current type is consistent with the alias index used during graph construction
235 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
236 bool consistent = adr_check == NULL || adr_check->empty() ||
237 phase->C->must_alias(adr_check, alias_idx );
238 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
239 if( !consistent && adr_check != NULL && !adr_check->empty() &&
240 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
241 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
242 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
243 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
244 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
245 // don't assert if it is dead code.
246 consistent = true;
247 }
248 if( !consistent ) {
249 st->print("alias_idx==%d, adr_check==", alias_idx);
250 if( adr_check == NULL ) {
251 st->print("NULL");
252 } else {
253 adr_check->dump();
254 }
255 st->cr();
256 print_alias_types();
257 assert(consistent, "adr_check must match alias idx");
258 }
259 }
260 #endif
261 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
262 // means an array I have not precisely typed yet. Do not do any
263 // alias stuff with it any time soon.
264 const TypeOopPtr *toop = tp->isa_oopptr();
265 if( tp->base() != Type::AnyPtr &&
266 !(toop &&
267 toop->klass() != NULL &&
268 toop->klass()->is_java_lang_Object() &&
269 toop->offset() == Type::OffsetBot) ) {
270 // compress paths and change unreachable cycles to TOP
271 // If not, we can update the input infinitely along a MergeMem cycle
272 // Equivalent code in PhiNode::Ideal
273 Node* m = phase->transform(mmem);
274 // If transformed to a MergeMem, get the desired slice
275 // Otherwise the returned node represents memory for every slice
276 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
277 // Update input if it is progress over what we have now
278 }
279 return mem;
280 }
281
282 //--------------------------Ideal_common---------------------------------------
283 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
284 // Unhook non-raw memories from complete (macro-expanded) initializations.
285 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
286 // If our control input is a dead region, kill all below the region
287 Node *ctl = in(MemNode::Control);
288 if (ctl && remove_dead_region(phase, can_reshape))
289 return this;
290 ctl = in(MemNode::Control);
291 // Don't bother trying to transform a dead node
292 if (ctl && ctl->is_top()) return NodeSentinel;
293
294 PhaseIterGVN *igvn = phase->is_IterGVN();
295 // Wait if control on the worklist.
296 if (ctl && can_reshape && igvn != NULL) {
297 Node* bol = NULL;
298 Node* cmp = NULL;
299 if (ctl->in(0)->is_If()) {
300 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
301 bol = ctl->in(0)->in(1);
302 if (bol->is_Bool())
303 cmp = ctl->in(0)->in(1)->in(1);
304 }
305 if (igvn->_worklist.member(ctl) ||
306 (bol != NULL && igvn->_worklist.member(bol)) ||
307 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
308 // This control path may be dead.
309 // Delay this memory node transformation until the control is processed.
310 phase->is_IterGVN()->_worklist.push(this);
311 return NodeSentinel; // caller will return NULL
312 }
313 }
314 // Ignore if memory is dead, or self-loop
315 Node *mem = in(MemNode::Memory);
316 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
317 assert(mem != this, "dead loop in MemNode::Ideal");
318
319 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
320 // This memory slice may be dead.
321 // Delay this mem node transformation until the memory is processed.
322 phase->is_IterGVN()->_worklist.push(this);
323 return NodeSentinel; // caller will return NULL
324 }
325
326 Node *address = in(MemNode::Address);
327 const Type *t_adr = phase->type(address);
328 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
329
330 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
331 // Unsafe off-heap access with zero address. Remove access and other control users
332 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
333 assert(ctl != NULL, "unsafe accesses should be control dependent");
334 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
335 Node* u = ctl->fast_out(i);
336 if (u != ctl) {
337 igvn->rehash_node_delayed(u);
338 int nb = u->replace_edge(ctl, phase->C->top());
339 --i, imax -= nb;
340 }
341 }
342 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
343 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
344 phase->C->root()->add_req(halt);
345 return this;
346 }
347
348 if (can_reshape && igvn != NULL &&
349 (igvn->_worklist.member(address) ||
350 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
351 // The address's base and type may change when the address is processed.
352 // Delay this mem node transformation until the address is processed.
353 phase->is_IterGVN()->_worklist.push(this);
354 return NodeSentinel; // caller will return NULL
355 }
356
357 // Do NOT remove or optimize the next lines: ensure a new alias index
358 // is allocated for an oop pointer type before Escape Analysis.
359 // Note: C++ will not remove it since the call has side effect.
360 if (t_adr->isa_oopptr()) {
361 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
362 }
363
364 Node* base = NULL;
365 if (address->is_AddP()) {
366 base = address->in(AddPNode::Base);
367 }
368 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
369 !t_adr->isa_rawptr()) {
370 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
371 // Skip this node optimization if its address has TOP base.
372 return NodeSentinel; // caller will return NULL
373 }
374
375 // Avoid independent memory operations
376 Node* old_mem = mem;
377
378 // The code which unhooks non-raw memories from complete (macro-expanded)
379 // initializations was removed. After macro-expansion all stores catched
380 // by Initialize node became raw stores and there is no information
381 // which memory slices they modify. So it is unsafe to move any memory
382 // operation above these stores. Also in most cases hooked non-raw memories
383 // were already unhooked by using information from detect_ptr_independence()
384 // and find_previous_store().
385
386 if (mem->is_MergeMem()) {
387 MergeMemNode* mmem = mem->as_MergeMem();
388 const TypePtr *tp = t_adr->is_ptr();
389
390 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
391 }
392
393 if (mem != old_mem) {
394 set_req(MemNode::Memory, mem);
395 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
396 igvn->_worklist.push(old_mem);
397 }
398 if (phase->type(mem) == Type::TOP) return NodeSentinel;
399 return this;
400 }
401
402 // let the subclass continue analyzing...
403 return NULL;
404 }
405
406 // Helper function for proving some simple control dominations.
407 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
408 // Already assumes that 'dom' is available at 'sub', and that 'sub'
409 // is not a constant (dominated by the method's StartNode).
410 // Used by MemNode::find_previous_store to prove that the
411 // control input of a memory operation predates (dominates)
412 // an allocation it wants to look past.
413 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
414 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
415 return false; // Conservative answer for dead code
416
417 // Check 'dom'. Skip Proj and CatchProj nodes.
418 dom = dom->find_exact_control(dom);
419 if (dom == NULL || dom->is_top())
420 return false; // Conservative answer for dead code
421
422 if (dom == sub) {
423 // For the case when, for example, 'sub' is Initialize and the original
424 // 'dom' is Proj node of the 'sub'.
425 return false;
426 }
427
428 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
429 return true;
430
431 // 'dom' dominates 'sub' if its control edge and control edges
432 // of all its inputs dominate or equal to sub's control edge.
433
434 // Currently 'sub' is either Allocate, Initialize or Start nodes.
435 // Or Region for the check in LoadNode::Ideal();
436 // 'sub' should have sub->in(0) != NULL.
437 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
438 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
439
440 // Get control edge of 'sub'.
441 Node* orig_sub = sub;
442 sub = sub->find_exact_control(sub->in(0));
443 if (sub == NULL || sub->is_top())
444 return false; // Conservative answer for dead code
445
446 assert(sub->is_CFG(), "expecting control");
447
448 if (sub == dom)
449 return true;
450
451 if (sub->is_Start() || sub->is_Root())
452 return false;
453
454 {
455 // Check all control edges of 'dom'.
456
457 ResourceMark rm;
458 Arena* arena = Thread::current()->resource_area();
459 Node_List nlist(arena);
460 Unique_Node_List dom_list(arena);
461
462 dom_list.push(dom);
463 bool only_dominating_controls = false;
464
465 for (uint next = 0; next < dom_list.size(); next++) {
466 Node* n = dom_list.at(next);
467 if (n == orig_sub)
468 return false; // One of dom's inputs dominated by sub.
469 if (!n->is_CFG() && n->pinned()) {
470 // Check only own control edge for pinned non-control nodes.
471 n = n->find_exact_control(n->in(0));
472 if (n == NULL || n->is_top())
473 return false; // Conservative answer for dead code
474 assert(n->is_CFG(), "expecting control");
475 dom_list.push(n);
476 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
477 only_dominating_controls = true;
478 } else if (n->is_CFG()) {
479 if (n->dominates(sub, nlist))
480 only_dominating_controls = true;
481 else
482 return false;
483 } else {
484 // First, own control edge.
485 Node* m = n->find_exact_control(n->in(0));
486 if (m != NULL) {
487 if (m->is_top())
488 return false; // Conservative answer for dead code
489 dom_list.push(m);
490 }
491 // Now, the rest of edges.
492 uint cnt = n->req();
493 for (uint i = 1; i < cnt; i++) {
494 m = n->find_exact_control(n->in(i));
495 if (m == NULL || m->is_top())
496 continue;
497 dom_list.push(m);
498 }
499 }
500 }
501 return only_dominating_controls;
502 }
503 }
504
505 //---------------------detect_ptr_independence---------------------------------
506 // Used by MemNode::find_previous_store to prove that two base
507 // pointers are never equal.
508 // The pointers are accompanied by their associated allocations,
509 // if any, which have been previously discovered by the caller.
510 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
511 Node* p2, AllocateNode* a2,
512 PhaseTransform* phase) {
513 // Attempt to prove that these two pointers cannot be aliased.
514 // They may both manifestly be allocations, and they should differ.
515 // Or, if they are not both allocations, they can be distinct constants.
516 // Otherwise, one is an allocation and the other a pre-existing value.
517 if (a1 == NULL && a2 == NULL) { // neither an allocation
518 return (p1 != p2) && p1->is_Con() && p2->is_Con();
519 } else if (a1 != NULL && a2 != NULL) { // both allocations
520 return (a1 != a2);
521 } else if (a1 != NULL) { // one allocation a1
522 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
523 return all_controls_dominate(p2, a1);
524 } else { //(a2 != NULL) // one allocation a2
525 return all_controls_dominate(p1, a2);
526 }
527 return false;
528 }
529
530
531 // Find an arraycopy that must have set (can_see_stored_value=true) or
532 // could have set (can_see_stored_value=false) the value for this load
533 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
534 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
535 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
536 Node* mb = mem->in(0);
537 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
538 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
539 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
540 if (ac->is_clonebasic()) {
541 intptr_t offset;
542 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
543 if (alloc != NULL && alloc == ld_alloc) {
544 return ac;
545 }
546 }
547 }
548 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
549 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
550
551 if (ac->is_arraycopy_validated() ||
552 ac->is_copyof_validated() ||
553 ac->is_copyofrange_validated()) {
554 Node* ld_addp = in(MemNode::Address);
555 if (ld_addp->is_AddP()) {
556 Node* ld_base = ld_addp->in(AddPNode::Address);
557 Node* ld_offs = ld_addp->in(AddPNode::Offset);
558
559 Node* dest = ac->in(ArrayCopyNode::Dest);
560
561 if (dest == ld_base) {
562 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
563 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
564 return ac;
565 }
566 if (!can_see_stored_value) {
567 mem = ac->in(TypeFunc::Memory);
568 }
569 }
570 }
571 }
572 }
573 return NULL;
574 }
575
576 // The logic for reordering loads and stores uses four steps:
577 // (a) Walk carefully past stores and initializations which we
578 // can prove are independent of this load.
579 // (b) Observe that the next memory state makes an exact match
580 // with self (load or store), and locate the relevant store.
581 // (c) Ensure that, if we were to wire self directly to the store,
582 // the optimizer would fold it up somehow.
583 // (d) Do the rewiring, and return, depending on some other part of
584 // the optimizer to fold up the load.
585 // This routine handles steps (a) and (b). Steps (c) and (d) are
586 // specific to loads and stores, so they are handled by the callers.
587 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
588 //
589 Node* MemNode::find_previous_store(PhaseTransform* phase) {
590 Node* ctrl = in(MemNode::Control);
591 Node* adr = in(MemNode::Address);
592 intptr_t offset = 0;
593 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
594 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
595
596 if (offset == Type::OffsetBot)
597 return NULL; // cannot unalias unless there are precise offsets
598
599 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
600 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
601
602 intptr_t size_in_bytes = memory_size();
603
604 Node* mem = in(MemNode::Memory); // start searching here...
605
606 int cnt = 50; // Cycle limiter
607 for (;;) { // While we can dance past unrelated stores...
608 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
609
610 Node* prev = mem;
611 if (mem->is_Store()) {
612 Node* st_adr = mem->in(MemNode::Address);
613 intptr_t st_offset = 0;
614 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
615 if (st_base == NULL)
616 break; // inscrutable pointer
617
618 // For raw accesses it's not enough to prove that constant offsets don't intersect.
619 // We need the bases to be the equal in order for the offset check to make sense.
620 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
621 break;
622 }
623
624 if (st_offset != offset && st_offset != Type::OffsetBot) {
625 const int MAX_STORE = BytesPerLong;
626 if (st_offset >= offset + size_in_bytes ||
627 st_offset <= offset - MAX_STORE ||
628 st_offset <= offset - mem->as_Store()->memory_size()) {
629 // Success: The offsets are provably independent.
630 // (You may ask, why not just test st_offset != offset and be done?
631 // The answer is that stores of different sizes can co-exist
632 // in the same sequence of RawMem effects. We sometimes initialize
633 // a whole 'tile' of array elements with a single jint or jlong.)
634 mem = mem->in(MemNode::Memory);
635 continue; // (a) advance through independent store memory
636 }
637 }
638 if (st_base != base &&
639 detect_ptr_independence(base, alloc,
640 st_base,
641 AllocateNode::Ideal_allocation(st_base, phase),
642 phase)) {
643 // Success: The bases are provably independent.
644 mem = mem->in(MemNode::Memory);
645 continue; // (a) advance through independent store memory
646 }
647
648 // (b) At this point, if the bases or offsets do not agree, we lose,
649 // since we have not managed to prove 'this' and 'mem' independent.
650 if (st_base == base && st_offset == offset) {
651 return mem; // let caller handle steps (c), (d)
652 }
653
654 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
655 InitializeNode* st_init = mem->in(0)->as_Initialize();
656 AllocateNode* st_alloc = st_init->allocation();
657 if (st_alloc == NULL)
658 break; // something degenerated
659 bool known_identical = false;
660 bool known_independent = false;
661 if (alloc == st_alloc)
662 known_identical = true;
663 else if (alloc != NULL)
664 known_independent = true;
665 else if (all_controls_dominate(this, st_alloc))
666 known_independent = true;
667
668 if (known_independent) {
669 // The bases are provably independent: Either they are
670 // manifestly distinct allocations, or else the control
671 // of this load dominates the store's allocation.
672 int alias_idx = phase->C->get_alias_index(adr_type());
673 if (alias_idx == Compile::AliasIdxRaw) {
674 mem = st_alloc->in(TypeFunc::Memory);
675 } else {
676 mem = st_init->memory(alias_idx);
677 }
678 continue; // (a) advance through independent store memory
679 }
680
681 // (b) at this point, if we are not looking at a store initializing
682 // the same allocation we are loading from, we lose.
683 if (known_identical) {
684 // From caller, can_see_stored_value will consult find_captured_store.
685 return mem; // let caller handle steps (c), (d)
686 }
687
688 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
689 if (prev != mem) {
690 // Found an arraycopy but it doesn't affect that load
691 continue;
692 }
693 // Found an arraycopy that may affect that load
694 return mem;
695 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
696 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
697 if (mem->is_Proj() && mem->in(0)->is_Call()) {
698 // ArrayCopyNodes processed here as well.
699 CallNode *call = mem->in(0)->as_Call();
700 if (!call->may_modify(addr_t, phase)) {
701 mem = call->in(TypeFunc::Memory);
702 continue; // (a) advance through independent call memory
703 }
704 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
705 ArrayCopyNode* ac = NULL;
706 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
707 break;
708 }
709 mem = mem->in(0)->in(TypeFunc::Memory);
710 continue; // (a) advance through independent MemBar memory
711 } else if (mem->is_ClearArray()) {
712 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
713 // (the call updated 'mem' value)
714 continue; // (a) advance through independent allocation memory
715 } else {
716 // Can not bypass initialization of the instance
717 // we are looking for.
718 return mem;
719 }
720 } else if (mem->is_MergeMem()) {
721 int alias_idx = phase->C->get_alias_index(adr_type());
722 mem = mem->as_MergeMem()->memory_at(alias_idx);
723 continue; // (a) advance through independent MergeMem memory
724 }
725 }
726
727 // Unless there is an explicit 'continue', we must bail out here,
728 // because 'mem' is an inscrutable memory state (e.g., a call).
729 break;
730 }
731
732 return NULL; // bail out
733 }
734
735 //----------------------calculate_adr_type-------------------------------------
736 // Helper function. Notices when the given type of address hits top or bottom.
737 // Also, asserts a cross-check of the type against the expected address type.
738 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
739 if (t == Type::TOP) return NULL; // does not touch memory any more?
740 #ifdef ASSERT
741 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
742 #endif
743 const TypePtr* tp = t->isa_ptr();
744 if (tp == NULL) {
745 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
746 return TypePtr::BOTTOM; // touches lots of memory
747 } else {
748 #ifdef ASSERT
749 // %%%% [phh] We don't check the alias index if cross_check is
750 // TypeRawPtr::BOTTOM. Needs to be investigated.
751 if (cross_check != NULL &&
752 cross_check != TypePtr::BOTTOM &&
753 cross_check != TypeRawPtr::BOTTOM) {
754 // Recheck the alias index, to see if it has changed (due to a bug).
755 Compile* C = Compile::current();
756 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
757 "must stay in the original alias category");
758 // The type of the address must be contained in the adr_type,
759 // disregarding "null"-ness.
760 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
761 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
762 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
763 "real address must not escape from expected memory type");
764 }
765 #endif
766 return tp;
767 }
768 }
769
770 //=============================================================================
771 // Should LoadNode::Ideal() attempt to remove control edges?
772 bool LoadNode::can_remove_control() const {
773 return true;
774 }
775 uint LoadNode::size_of() const { return sizeof(*this); }
776 bool LoadNode::cmp( const Node &n ) const
777 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
778 const Type *LoadNode::bottom_type() const { return _type; }
779 uint LoadNode::ideal_reg() const {
780 return _type->ideal_reg();
781 }
782
783 #ifndef PRODUCT
784 void LoadNode::dump_spec(outputStream *st) const {
785 MemNode::dump_spec(st);
786 if( !Verbose && !WizardMode ) {
787 // standard dump does this in Verbose and WizardMode
788 st->print(" #"); _type->dump_on(st);
789 }
790 if (!depends_only_on_test()) {
791 st->print(" (does not depend only on test)");
792 }
793 }
794 #endif
795
796 #ifdef ASSERT
797 //----------------------------is_immutable_value-------------------------------
798 // Helper function to allow a raw load without control edge for some cases
799 bool LoadNode::is_immutable_value(Node* adr) {
800 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
801 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
802 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
803 in_bytes(JavaThread::osthread_offset())));
804 }
805 #endif
806
807 //----------------------------LoadNode::make-----------------------------------
808 // Polymorphic factory method:
809 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
810 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
811 Compile* C = gvn.C;
812
813 // sanity check the alias category against the created node type
814 assert(!(adr_type->isa_oopptr() &&
815 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
816 "use LoadKlassNode instead");
817 assert(!(adr_type->isa_aryptr() &&
818 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
819 "use LoadRangeNode instead");
820 // Check control edge of raw loads
821 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
822 // oop will be recorded in oop map if load crosses safepoint
823 rt->isa_oopptr() || is_immutable_value(adr),
824 "raw memory operations should have control edge");
825 LoadNode* load = NULL;
826 switch (bt) {
827 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
828 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
829 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
830 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
831 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
832 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
833 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
834 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
835 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
836 case T_VALUETYPE:
837 case T_OBJECT:
838 #ifdef _LP64
839 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
840 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
841 } else
842 #endif
843 {
844 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
845 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
846 }
847 break;
848 default:
849 ShouldNotReachHere();
850 break;
851 }
852 assert(load != NULL, "LoadNode should have been created");
853 if (unaligned) {
854 load->set_unaligned_access();
855 }
856 if (mismatched) {
857 load->set_mismatched_access();
858 }
859 if (unsafe) {
860 load->set_unsafe_access();
861 }
862 load->set_barrier_data(barrier_data);
863 if (load->Opcode() == Op_LoadN) {
864 Node* ld = gvn.transform(load);
865 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
866 }
867
868 return load;
869 }
870
871 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
872 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
873 bool require_atomic = true;
874 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
875 if (unaligned) {
876 load->set_unaligned_access();
877 }
878 if (mismatched) {
879 load->set_mismatched_access();
880 }
881 if (unsafe) {
882 load->set_unsafe_access();
883 }
884 load->set_barrier_data(barrier_data);
885 return load;
886 }
887
888 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
889 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
890 bool require_atomic = true;
891 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
892 if (unaligned) {
893 load->set_unaligned_access();
894 }
895 if (mismatched) {
896 load->set_mismatched_access();
897 }
898 if (unsafe) {
899 load->set_unsafe_access();
900 }
901 load->set_barrier_data(barrier_data);
902 return load;
903 }
904
905
906
907 //------------------------------hash-------------------------------------------
908 uint LoadNode::hash() const {
909 // unroll addition of interesting fields
910 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
911 }
912
913 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
914 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
915 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
916 bool is_stable_ary = FoldStableValues &&
917 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
918 tp->isa_aryptr()->is_stable();
919
920 return (eliminate_boxing && non_volatile) || is_stable_ary;
921 }
922
923 return false;
924 }
925
926 // Is the value loaded previously stored by an arraycopy? If so return
927 // a load node that reads from the source array so we may be able to
928 // optimize out the ArrayCopy node later.
929 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
930 Node* ld_adr = in(MemNode::Address);
931 intptr_t ld_off = 0;
932 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
933 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
934 if (ac != NULL) {
935 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
936
937 Node* mem = ac->in(TypeFunc::Memory);
938 Node* ctl = ac->in(0);
939 Node* src = ac->in(ArrayCopyNode::Src);
940
941 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
942 return NULL;
943 }
944
945 LoadNode* ld = clone()->as_Load();
946 Node* addp = in(MemNode::Address)->clone();
947 if (ac->as_ArrayCopy()->is_clonebasic()) {
948 assert(ld_alloc != NULL, "need an alloc");
949 assert(addp->is_AddP(), "address must be addp");
950 assert(ac->in(ArrayCopyNode::Dest)->is_AddP(), "dest must be an address");
951 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
952 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base)), "strange pattern");
953 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address)), "strange pattern");
954 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
955 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
956 } else {
957 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
958 ac->as_ArrayCopy()->is_copyof_validated() ||
959 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
960 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
961 addp->set_req(AddPNode::Base, src);
962 addp->set_req(AddPNode::Address, src);
963
964 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
965 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
966 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
967 uint shift = exact_log2(type2aelembytes(ary_elem));
968 if (ary_t->klass()->is_value_array_klass()) {
969 ciValueArrayKlass* vak = ary_t->klass()->as_value_array_klass();
970 shift = vak->log2_element_size();
971 }
972
973 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
974 #ifdef _LP64
975 diff = phase->transform(new ConvI2LNode(diff));
976 #endif
977 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
978
979 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
980 addp->set_req(AddPNode::Offset, offset);
981 }
982 addp = phase->transform(addp);
983 #ifdef ASSERT
984 const TypePtr* adr_type = phase->type(addp)->is_ptr();
985 ld->_adr_type = adr_type;
986 #endif
987 ld->set_req(MemNode::Address, addp);
988 ld->set_req(0, ctl);
989 ld->set_req(MemNode::Memory, mem);
990 // load depends on the tests that validate the arraycopy
991 ld->_control_dependency = UnknownControl;
992 return ld;
993 }
994 return NULL;
995 }
996
997
998 //---------------------------can_see_stored_value------------------------------
999 // This routine exists to make sure this set of tests is done the same
1000 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1001 // will change the graph shape in a way which makes memory alive twice at the
1002 // same time (uses the Oracle model of aliasing), then some
1003 // LoadXNode::Identity will fold things back to the equivalence-class model
1004 // of aliasing.
1005 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1006 Node* ld_adr = in(MemNode::Address);
1007 intptr_t ld_off = 0;
1008 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1009 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1010 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1011 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1012 // This is more general than load from boxing objects.
1013 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1014 uint alias_idx = atp->index();
1015 bool final = !atp->is_rewritable();
1016 Node* result = NULL;
1017 Node* current = st;
1018 // Skip through chains of MemBarNodes checking the MergeMems for
1019 // new states for the slice of this load. Stop once any other
1020 // kind of node is encountered. Loads from final memory can skip
1021 // through any kind of MemBar but normal loads shouldn't skip
1022 // through MemBarAcquire since the could allow them to move out of
1023 // a synchronized region.
1024 while (current->is_Proj()) {
1025 int opc = current->in(0)->Opcode();
1026 if ((final && (opc == Op_MemBarAcquire ||
1027 opc == Op_MemBarAcquireLock ||
1028 opc == Op_LoadFence)) ||
1029 opc == Op_MemBarRelease ||
1030 opc == Op_StoreFence ||
1031 opc == Op_MemBarReleaseLock ||
1032 opc == Op_MemBarStoreStore ||
1033 opc == Op_MemBarCPUOrder) {
1034 Node* mem = current->in(0)->in(TypeFunc::Memory);
1035 if (mem->is_MergeMem()) {
1036 MergeMemNode* merge = mem->as_MergeMem();
1037 Node* new_st = merge->memory_at(alias_idx);
1038 if (new_st == merge->base_memory()) {
1039 // Keep searching
1040 current = new_st;
1041 continue;
1042 }
1043 // Save the new memory state for the slice and fall through
1044 // to exit.
1045 result = new_st;
1046 }
1047 }
1048 break;
1049 }
1050 if (result != NULL) {
1051 st = result;
1052 }
1053 }
1054
1055 // Loop around twice in the case Load -> Initialize -> Store.
1056 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1057 for (int trip = 0; trip <= 1; trip++) {
1058
1059 if (st->is_Store()) {
1060 Node* st_adr = st->in(MemNode::Address);
1061 if (!phase->eqv(st_adr, ld_adr)) {
1062 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1063 intptr_t st_off = 0;
1064 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1065 if (ld_base == NULL) return NULL;
1066 if (st_base == NULL) return NULL;
1067 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL;
1068 if (ld_off != st_off) return NULL;
1069 if (ld_off == Type::OffsetBot) return NULL;
1070 // Same base, same offset.
1071 // Possible improvement for arrays: check index value instead of absolute offset.
1072
1073 // At this point we have proven something like this setup:
1074 // B = << base >>
1075 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1076 // S = StoreQ(AddP( B , #Off), V)
1077 // (Actually, we haven't yet proven the Q's are the same.)
1078 // In other words, we are loading from a casted version of
1079 // the same pointer-and-offset that we stored to.
1080 // Casted version may carry a dependency and it is respected.
1081 // Thus, we are able to replace L by V.
1082 }
1083 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1084 if (store_Opcode() != st->Opcode())
1085 return NULL;
1086 return st->in(MemNode::ValueIn);
1087 }
1088
1089 // A load from a freshly-created object always returns zero.
1090 // (This can happen after LoadNode::Ideal resets the load's memory input
1091 // to find_captured_store, which returned InitializeNode::zero_memory.)
1092 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1093 (st->in(0) == ld_alloc) &&
1094 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1095 // return a zero value for the load's basic type
1096 // (This is one of the few places where a generic PhaseTransform
1097 // can create new nodes. Think of it as lazily manifesting
1098 // virtually pre-existing constants.)
1099 assert(memory_type() != T_VALUETYPE, "should not be used for value types");
1100 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1101 if (default_value != NULL) {
1102 return default_value;
1103 }
1104 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null");
1105 return phase->zerocon(memory_type());
1106 }
1107
1108 // A load from an initialization barrier can match a captured store.
1109 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1110 InitializeNode* init = st->in(0)->as_Initialize();
1111 AllocateNode* alloc = init->allocation();
1112 if ((alloc != NULL) && (alloc == ld_alloc)) {
1113 // examine a captured store value
1114 st = init->find_captured_store(ld_off, memory_size(), phase);
1115 if (st != NULL) {
1116 continue; // take one more trip around
1117 }
1118 }
1119 }
1120
1121 // Load boxed value from result of valueOf() call is input parameter.
1122 if (this->is_Load() && ld_adr->is_AddP() &&
1123 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1124 intptr_t ignore = 0;
1125 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1126 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1127 base = bs->step_over_gc_barrier(base);
1128 if (base != NULL && base->is_Proj() &&
1129 base->as_Proj()->_con == TypeFunc::Parms &&
1130 base->in(0)->is_CallStaticJava() &&
1131 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1132 return base->in(0)->in(TypeFunc::Parms);
1133 }
1134 }
1135
1136 break;
1137 }
1138
1139 return NULL;
1140 }
1141
1142 //----------------------is_instance_field_load_with_local_phi------------------
1143 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1144 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1145 in(Address)->is_AddP() ) {
1146 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1147 // Only instances and boxed values.
1148 if( t_oop != NULL &&
1149 (t_oop->is_ptr_to_boxed_value() ||
1150 t_oop->is_known_instance_field()) &&
1151 t_oop->offset() != Type::OffsetBot &&
1152 t_oop->offset() != Type::OffsetTop) {
1153 return true;
1154 }
1155 }
1156 return false;
1157 }
1158
1159 //------------------------------Identity---------------------------------------
1160 // Loads are identity if previous store is to same address
1161 Node* LoadNode::Identity(PhaseGVN* phase) {
1162 // Loading from a ValueTypePtr? The ValueTypePtr has the values of
1163 // all fields as input. Look for the field with matching offset.
1164 Node* addr = in(Address);
1165 intptr_t offset;
1166 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1167 if (base != NULL && base->is_ValueTypePtr() && offset > oopDesc::klass_offset_in_bytes()) {
1168 Node* value = base->as_ValueTypePtr()->field_value_by_offset((int)offset, true);
1169 if (value->is_ValueType()) {
1170 // Non-flattened value type field
1171 ValueTypeNode* vt = value->as_ValueType();
1172 if (vt->is_allocated(phase)) {
1173 value = vt->get_oop();
1174 } else {
1175 // Not yet allocated, bail out
1176 value = NULL;
1177 }
1178 }
1179 if (value != NULL) {
1180 if (Opcode() == Op_LoadN) {
1181 // Encode oop value if we are loading a narrow oop
1182 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1183 value = phase->transform(new EncodePNode(value, bottom_type()));
1184 }
1185 return value;
1186 }
1187 }
1188
1189 // If the previous store-maker is the right kind of Store, and the store is
1190 // to the same address, then we are equal to the value stored.
1191 Node* mem = in(Memory);
1192 Node* value = can_see_stored_value(mem, phase);
1193 if( value ) {
1194 // byte, short & char stores truncate naturally.
1195 // A load has to load the truncated value which requires
1196 // some sort of masking operation and that requires an
1197 // Ideal call instead of an Identity call.
1198 if (memory_size() < BytesPerInt) {
1199 // If the input to the store does not fit with the load's result type,
1200 // it must be truncated via an Ideal call.
1201 if (!phase->type(value)->higher_equal(phase->type(this)))
1202 return this;
1203 }
1204 // (This works even when value is a Con, but LoadNode::Value
1205 // usually runs first, producing the singleton type of the Con.)
1206 return value;
1207 }
1208
1209 // Search for an existing data phi which was generated before for the same
1210 // instance's field to avoid infinite generation of phis in a loop.
1211 Node *region = mem->in(0);
1212 if (is_instance_field_load_with_local_phi(region)) {
1213 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1214 int this_index = phase->C->get_alias_index(addr_t);
1215 int this_offset = addr_t->offset();
1216 int this_iid = addr_t->instance_id();
1217 if (!addr_t->is_known_instance() &&
1218 addr_t->is_ptr_to_boxed_value()) {
1219 // Use _idx of address base (could be Phi node) for boxed values.
1220 intptr_t ignore = 0;
1221 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1222 if (base == NULL) {
1223 return this;
1224 }
1225 this_iid = base->_idx;
1226 }
1227 const Type* this_type = bottom_type();
1228 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1229 Node* phi = region->fast_out(i);
1230 if (phi->is_Phi() && phi != mem &&
1231 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1232 return phi;
1233 }
1234 }
1235 }
1236
1237 return this;
1238 }
1239
1240 // Construct an equivalent unsigned load.
1241 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1242 BasicType bt = T_ILLEGAL;
1243 const Type* rt = NULL;
1244 switch (Opcode()) {
1245 case Op_LoadUB: return this;
1246 case Op_LoadUS: return this;
1247 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1248 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1249 default:
1250 assert(false, "no unsigned variant: %s", Name());
1251 return NULL;
1252 }
1253 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1254 raw_adr_type(), rt, bt, _mo, _control_dependency,
1255 is_unaligned_access(), is_mismatched_access());
1256 }
1257
1258 // Construct an equivalent signed load.
1259 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1260 BasicType bt = T_ILLEGAL;
1261 const Type* rt = NULL;
1262 switch (Opcode()) {
1263 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1264 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1265 case Op_LoadB: // fall through
1266 case Op_LoadS: // fall through
1267 case Op_LoadI: // fall through
1268 case Op_LoadL: return this;
1269 default:
1270 assert(false, "no signed variant: %s", Name());
1271 return NULL;
1272 }
1273 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1274 raw_adr_type(), rt, bt, _mo, _control_dependency,
1275 is_unaligned_access(), is_mismatched_access());
1276 }
1277
1278 // We're loading from an object which has autobox behaviour.
1279 // If this object is result of a valueOf call we'll have a phi
1280 // merging a newly allocated object and a load from the cache.
1281 // We want to replace this load with the original incoming
1282 // argument to the valueOf call.
1283 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1284 assert(phase->C->eliminate_boxing(), "sanity");
1285 intptr_t ignore = 0;
1286 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1287 if ((base == NULL) || base->is_Phi()) {
1288 // Push the loads from the phi that comes from valueOf up
1289 // through it to allow elimination of the loads and the recovery
1290 // of the original value. It is done in split_through_phi().
1291 return NULL;
1292 } else if (base->is_Load() ||
1293 (base->is_DecodeN() && base->in(1)->is_Load())) {
1294 // Eliminate the load of boxed value for integer types from the cache
1295 // array by deriving the value from the index into the array.
1296 // Capture the offset of the load and then reverse the computation.
1297
1298 // Get LoadN node which loads a boxing object from 'cache' array.
1299 if (base->is_DecodeN()) {
1300 base = base->in(1);
1301 }
1302 if (!base->in(Address)->is_AddP()) {
1303 return NULL; // Complex address
1304 }
1305 AddPNode* address = base->in(Address)->as_AddP();
1306 Node* cache_base = address->in(AddPNode::Base);
1307 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1308 // Get ConP node which is static 'cache' field.
1309 cache_base = cache_base->in(1);
1310 }
1311 if ((cache_base != NULL) && cache_base->is_Con()) {
1312 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1313 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1314 Node* elements[4];
1315 int shift = exact_log2(type2aelembytes(T_OBJECT));
1316 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1317 if (count > 0 && elements[0]->is_Con() &&
1318 (count == 1 ||
1319 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1320 elements[1]->in(2) == phase->intcon(shift)))) {
1321 ciObjArray* array = base_type->const_oop()->as_obj_array();
1322 // Fetch the box object cache[0] at the base of the array and get its value
1323 ciInstance* box = array->obj_at(0)->as_instance();
1324 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1325 assert(ik->is_box_klass(), "sanity");
1326 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1327 if (ik->nof_nonstatic_fields() == 1) {
1328 // This should be true nonstatic_field_at requires calling
1329 // nof_nonstatic_fields so check it anyway
1330 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1331 BasicType bt = c.basic_type();
1332 // Only integer types have boxing cache.
1333 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1334 bt == T_BYTE || bt == T_SHORT ||
1335 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1336 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1337 if (cache_low != (int)cache_low) {
1338 return NULL; // should not happen since cache is array indexed by value
1339 }
1340 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1341 if (offset != (int)offset) {
1342 return NULL; // should not happen since cache is array indexed by value
1343 }
1344 // Add up all the offsets making of the address of the load
1345 Node* result = elements[0];
1346 for (int i = 1; i < count; i++) {
1347 result = phase->transform(new AddXNode(result, elements[i]));
1348 }
1349 // Remove the constant offset from the address and then
1350 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1351 // remove the scaling of the offset to recover the original index.
1352 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1353 // Peel the shift off directly but wrap it in a dummy node
1354 // since Ideal can't return existing nodes
1355 result = new RShiftXNode(result->in(1), phase->intcon(0));
1356 } else if (result->is_Add() && result->in(2)->is_Con() &&
1357 result->in(1)->Opcode() == Op_LShiftX &&
1358 result->in(1)->in(2) == phase->intcon(shift)) {
1359 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1360 // but for boxing cache access we know that X<<Z will not overflow
1361 // (there is range check) so we do this optimizatrion by hand here.
1362 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1363 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1364 } else {
1365 result = new RShiftXNode(result, phase->intcon(shift));
1366 }
1367 #ifdef _LP64
1368 if (bt != T_LONG) {
1369 result = new ConvL2INode(phase->transform(result));
1370 }
1371 #else
1372 if (bt == T_LONG) {
1373 result = new ConvI2LNode(phase->transform(result));
1374 }
1375 #endif
1376 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1377 // Need to preserve unboxing load type if it is unsigned.
1378 switch(this->Opcode()) {
1379 case Op_LoadUB:
1380 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1381 break;
1382 case Op_LoadUS:
1383 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1384 break;
1385 }
1386 return result;
1387 }
1388 }
1389 }
1390 }
1391 }
1392 return NULL;
1393 }
1394
1395 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1396 Node* region = phi->in(0);
1397 if (region == NULL) {
1398 return false; // Wait stable graph
1399 }
1400 uint cnt = phi->req();
1401 for (uint i = 1; i < cnt; i++) {
1402 Node* rc = region->in(i);
1403 if (rc == NULL || phase->type(rc) == Type::TOP)
1404 return false; // Wait stable graph
1405 Node* in = phi->in(i);
1406 if (in == NULL || phase->type(in) == Type::TOP)
1407 return false; // Wait stable graph
1408 }
1409 return true;
1410 }
1411 //------------------------------split_through_phi------------------------------
1412 // Split instance or boxed field load through Phi.
1413 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1414 Node* mem = in(Memory);
1415 Node* address = in(Address);
1416 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1417
1418 assert((t_oop != NULL) &&
1419 (t_oop->is_known_instance_field() ||
1420 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1421
1422 Compile* C = phase->C;
1423 intptr_t ignore = 0;
1424 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1425 bool base_is_phi = (base != NULL) && base->is_Phi();
1426 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1427 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1428 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1429
1430 if (!((mem->is_Phi() || base_is_phi) &&
1431 (load_boxed_values || t_oop->is_known_instance_field()))) {
1432 return NULL; // memory is not Phi
1433 }
1434
1435 if (mem->is_Phi()) {
1436 if (!stable_phi(mem->as_Phi(), phase)) {
1437 return NULL; // Wait stable graph
1438 }
1439 uint cnt = mem->req();
1440 // Check for loop invariant memory.
1441 if (cnt == 3) {
1442 for (uint i = 1; i < cnt; i++) {
1443 Node* in = mem->in(i);
1444 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1445 if (m == mem) {
1446 if (i == 1) {
1447 // if the first edge was a loop, check second edge too.
1448 // If both are replaceable - we are in an infinite loop
1449 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1450 if (n == mem) {
1451 break;
1452 }
1453 }
1454 set_req(Memory, mem->in(cnt - i));
1455 return this; // made change
1456 }
1457 }
1458 }
1459 }
1460 if (base_is_phi) {
1461 if (!stable_phi(base->as_Phi(), phase)) {
1462 return NULL; // Wait stable graph
1463 }
1464 uint cnt = base->req();
1465 // Check for loop invariant memory.
1466 if (cnt == 3) {
1467 for (uint i = 1; i < cnt; i++) {
1468 if (base->in(i) == base) {
1469 return NULL; // Wait stable graph
1470 }
1471 }
1472 }
1473 }
1474
1475 // Split through Phi (see original code in loopopts.cpp).
1476 assert(C->have_alias_type(t_oop), "instance should have alias type");
1477
1478 // Do nothing here if Identity will find a value
1479 // (to avoid infinite chain of value phis generation).
1480 if (!phase->eqv(this, phase->apply_identity(this)))
1481 return NULL;
1482
1483 // Select Region to split through.
1484 Node* region;
1485 if (!base_is_phi) {
1486 assert(mem->is_Phi(), "sanity");
1487 region = mem->in(0);
1488 // Skip if the region dominates some control edge of the address.
1489 if (!MemNode::all_controls_dominate(address, region))
1490 return NULL;
1491 } else if (!mem->is_Phi()) {
1492 assert(base_is_phi, "sanity");
1493 region = base->in(0);
1494 // Skip if the region dominates some control edge of the memory.
1495 if (!MemNode::all_controls_dominate(mem, region))
1496 return NULL;
1497 } else if (base->in(0) != mem->in(0)) {
1498 assert(base_is_phi && mem->is_Phi(), "sanity");
1499 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1500 region = base->in(0);
1501 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1502 region = mem->in(0);
1503 } else {
1504 return NULL; // complex graph
1505 }
1506 } else {
1507 assert(base->in(0) == mem->in(0), "sanity");
1508 region = mem->in(0);
1509 }
1510
1511 const Type* this_type = this->bottom_type();
1512 int this_index = C->get_alias_index(t_oop);
1513 int this_offset = t_oop->offset();
1514 int this_iid = t_oop->instance_id();
1515 if (!t_oop->is_known_instance() && load_boxed_values) {
1516 // Use _idx of address base for boxed values.
1517 this_iid = base->_idx;
1518 }
1519 PhaseIterGVN* igvn = phase->is_IterGVN();
1520 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1521 for (uint i = 1; i < region->req(); i++) {
1522 Node* x;
1523 Node* the_clone = NULL;
1524 if (region->in(i) == C->top()) {
1525 x = C->top(); // Dead path? Use a dead data op
1526 } else {
1527 x = this->clone(); // Else clone up the data op
1528 the_clone = x; // Remember for possible deletion.
1529 // Alter data node to use pre-phi inputs
1530 if (this->in(0) == region) {
1531 x->set_req(0, region->in(i));
1532 } else {
1533 x->set_req(0, NULL);
1534 }
1535 if (mem->is_Phi() && (mem->in(0) == region)) {
1536 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1537 }
1538 if (address->is_Phi() && address->in(0) == region) {
1539 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1540 }
1541 if (base_is_phi && (base->in(0) == region)) {
1542 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1543 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1544 x->set_req(Address, adr_x);
1545 }
1546 }
1547 // Check for a 'win' on some paths
1548 const Type *t = x->Value(igvn);
1549
1550 bool singleton = t->singleton();
1551
1552 // See comments in PhaseIdealLoop::split_thru_phi().
1553 if (singleton && t == Type::TOP) {
1554 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1555 }
1556
1557 if (singleton) {
1558 x = igvn->makecon(t);
1559 } else {
1560 // We now call Identity to try to simplify the cloned node.
1561 // Note that some Identity methods call phase->type(this).
1562 // Make sure that the type array is big enough for
1563 // our new node, even though we may throw the node away.
1564 // (This tweaking with igvn only works because x is a new node.)
1565 igvn->set_type(x, t);
1566 // If x is a TypeNode, capture any more-precise type permanently into Node
1567 // otherwise it will be not updated during igvn->transform since
1568 // igvn->type(x) is set to x->Value() already.
1569 x->raise_bottom_type(t);
1570 Node *y = igvn->apply_identity(x);
1571 if (y != x) {
1572 x = y;
1573 } else {
1574 y = igvn->hash_find_insert(x);
1575 if (y) {
1576 x = y;
1577 } else {
1578 // Else x is a new node we are keeping
1579 // We do not need register_new_node_with_optimizer
1580 // because set_type has already been called.
1581 igvn->_worklist.push(x);
1582 }
1583 }
1584 }
1585 if (x != the_clone && the_clone != NULL) {
1586 igvn->remove_dead_node(the_clone);
1587 }
1588 phi->set_req(i, x);
1589 }
1590 // Record Phi
1591 igvn->register_new_node_with_optimizer(phi);
1592 return phi;
1593 }
1594
1595 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1596 if (Opcode() == Op_LoadX) {
1597 Node* address = in(MemNode::Address);
1598 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1599 Node* mem = in(MemNode::Memory);
1600 if (alloc != NULL && mem->is_Proj() &&
1601 mem->in(0) != NULL &&
1602 mem->in(0) == alloc->initialization() &&
1603 alloc->initialization()->proj_out_or_null(0) != NULL) {
1604 return alloc;
1605 }
1606 }
1607 return NULL;
1608 }
1609
1610
1611 //------------------------------Ideal------------------------------------------
1612 // If the load is from Field memory and the pointer is non-null, it might be possible to
1613 // zero out the control input.
1614 // If the offset is constant and the base is an object allocation,
1615 // try to hook me up to the exact initializing store.
1616 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1617 Node* p = MemNode::Ideal_common(phase, can_reshape);
1618 if (p) return (p == NodeSentinel) ? NULL : p;
1619
1620 Node* ctrl = in(MemNode::Control);
1621 Node* address = in(MemNode::Address);
1622 bool progress = false;
1623
1624 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1625 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1626
1627 // Skip up past a SafePoint control. Cannot do this for Stores because
1628 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1629 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1630 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1631 !addr_mark &&
1632 (depends_only_on_test() || has_unknown_control_dependency())) {
1633 ctrl = ctrl->in(0);
1634 set_req(MemNode::Control,ctrl);
1635 progress = true;
1636 }
1637
1638 intptr_t ignore = 0;
1639 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1640 if (base != NULL
1641 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1642 // Check for useless control edge in some common special cases
1643 if (in(MemNode::Control) != NULL
1644 && can_remove_control()
1645 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1646 && all_controls_dominate(base, phase->C->start())) {
1647 // A method-invariant, non-null address (constant or 'this' argument).
1648 set_req(MemNode::Control, NULL);
1649 progress = true;
1650 }
1651 }
1652
1653 Node* mem = in(MemNode::Memory);
1654 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1655
1656 if (can_reshape && (addr_t != NULL)) {
1657 // try to optimize our memory input
1658 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1659 if (opt_mem != mem) {
1660 set_req(MemNode::Memory, opt_mem);
1661 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1662 return this;
1663 }
1664 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1665 if ((t_oop != NULL) &&
1666 (t_oop->is_known_instance_field() ||
1667 t_oop->is_ptr_to_boxed_value())) {
1668 PhaseIterGVN *igvn = phase->is_IterGVN();
1669 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1670 // Delay this transformation until memory Phi is processed.
1671 phase->is_IterGVN()->_worklist.push(this);
1672 return NULL;
1673 }
1674 // Split instance field load through Phi.
1675 Node* result = split_through_phi(phase);
1676 if (result != NULL) return result;
1677
1678 if (t_oop->is_ptr_to_boxed_value()) {
1679 Node* result = eliminate_autobox(phase);
1680 if (result != NULL) return result;
1681 }
1682 }
1683 }
1684
1685 // Is there a dominating load that loads the same value? Leave
1686 // anything that is not a load of a field/array element (like
1687 // barriers etc.) alone
1688 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1689 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1690 Node *use = mem->fast_out(i);
1691 if (use != this &&
1692 use->Opcode() == Opcode() &&
1693 use->in(0) != NULL &&
1694 use->in(0) != in(0) &&
1695 use->in(Address) == in(Address)) {
1696 Node* ctl = in(0);
1697 for (int i = 0; i < 10 && ctl != NULL; i++) {
1698 ctl = IfNode::up_one_dom(ctl);
1699 if (ctl == use->in(0)) {
1700 set_req(0, use->in(0));
1701 return this;
1702 }
1703 }
1704 }
1705 }
1706 }
1707
1708 // Check for prior store with a different base or offset; make Load
1709 // independent. Skip through any number of them. Bail out if the stores
1710 // are in an endless dead cycle and report no progress. This is a key
1711 // transform for Reflection. However, if after skipping through the Stores
1712 // we can't then fold up against a prior store do NOT do the transform as
1713 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1714 // array memory alive twice: once for the hoisted Load and again after the
1715 // bypassed Store. This situation only works if EVERYBODY who does
1716 // anti-dependence work knows how to bypass. I.e. we need all
1717 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1718 // the alias index stuff. So instead, peek through Stores and IFF we can
1719 // fold up, do so.
1720 Node* prev_mem = find_previous_store(phase);
1721 if (prev_mem != NULL) {
1722 Node* value = can_see_arraycopy_value(prev_mem, phase);
1723 if (value != NULL) {
1724 return value;
1725 }
1726 }
1727 // Steps (a), (b): Walk past independent stores to find an exact match.
1728 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1729 // (c) See if we can fold up on the spot, but don't fold up here.
1730 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1731 // just return a prior value, which is done by Identity calls.
1732 if (can_see_stored_value(prev_mem, phase)) {
1733 // Make ready for step (d):
1734 set_req(MemNode::Memory, prev_mem);
1735 return this;
1736 }
1737 }
1738
1739 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1740 if (alloc != NULL && mem->is_Proj() &&
1741 mem->in(0) != NULL &&
1742 mem->in(0) == alloc->initialization() &&
1743 Opcode() == Op_LoadX &&
1744 alloc->initialization()->proj_out_or_null(0) != NULL) {
1745 InitializeNode* init = alloc->initialization();
1746 Node* control = init->proj_out(0);
1747 return alloc->make_ideal_mark(phase, address, control, mem);
1748 }
1749
1750 return progress ? this : NULL;
1751 }
1752
1753 // Helper to recognize certain Klass fields which are invariant across
1754 // some group of array types (e.g., int[] or all T[] where T < Object).
1755 const Type*
1756 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1757 ciKlass* klass) const {
1758 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1759 // The field is Klass::_modifier_flags. Return its (constant) value.
1760 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1761 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1762 return TypeInt::make(klass->modifier_flags());
1763 }
1764 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1765 // The field is Klass::_access_flags. Return its (constant) value.
1766 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1767 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1768 return TypeInt::make(klass->access_flags());
1769 }
1770 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1771 // The field is Klass::_layout_helper. Return its constant value if known.
1772 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1773 return TypeInt::make(klass->layout_helper());
1774 }
1775
1776 // No match.
1777 return NULL;
1778 }
1779
1780 //------------------------------Value-----------------------------------------
1781 const Type* LoadNode::Value(PhaseGVN* phase) const {
1782 // Either input is TOP ==> the result is TOP
1783 Node* mem = in(MemNode::Memory);
1784 const Type *t1 = phase->type(mem);
1785 if (t1 == Type::TOP) return Type::TOP;
1786 Node* adr = in(MemNode::Address);
1787 const TypePtr* tp = phase->type(adr)->isa_ptr();
1788 if (tp == NULL || tp->empty()) return Type::TOP;
1789 int off = tp->offset();
1790 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1791 Compile* C = phase->C;
1792
1793 // Try to guess loaded type from pointer type
1794 if (tp->isa_aryptr()) {
1795 const TypeAryPtr* ary = tp->is_aryptr();
1796 const Type* t = ary->elem();
1797
1798 // Determine whether the reference is beyond the header or not, by comparing
1799 // the offset against the offset of the start of the array's data.
1800 // Different array types begin at slightly different offsets (12 vs. 16).
1801 // We choose T_BYTE as an example base type that is least restrictive
1802 // as to alignment, which will therefore produce the smallest
1803 // possible base offset.
1804 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1805 const bool off_beyond_header = (off >= min_base_off);
1806
1807 // Try to constant-fold a stable array element.
1808 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1809 // Make sure the reference is not into the header and the offset is constant
1810 ciObject* aobj = ary->const_oop();
1811 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1812 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1813 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1814 stable_dimension,
1815 memory_type(), is_unsigned());
1816 if (con_type != NULL) {
1817 return con_type;
1818 }
1819 }
1820 }
1821
1822 // Don't do this for integer types. There is only potential profit if
1823 // the element type t is lower than _type; that is, for int types, if _type is
1824 // more restrictive than t. This only happens here if one is short and the other
1825 // char (both 16 bits), and in those cases we've made an intentional decision
1826 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1827 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1828 //
1829 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1830 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1831 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1832 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1833 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1834 // In fact, that could have been the original type of p1, and p1 could have
1835 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1836 // expression (LShiftL quux 3) independently optimized to the constant 8.
1837 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1838 && (_type->isa_vect() == NULL)
1839 && t->isa_valuetype() == NULL
1840 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1841 // t might actually be lower than _type, if _type is a unique
1842 // concrete subclass of abstract class t.
1843 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1844 const Type* jt = t->join_speculative(_type);
1845 // In any case, do not allow the join, per se, to empty out the type.
1846 if (jt->empty() && !t->empty()) {
1847 // This can happen if a interface-typed array narrows to a class type.
1848 jt = _type;
1849 }
1850 #ifdef ASSERT
1851 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1852 // The pointers in the autobox arrays are always non-null
1853 Node* base = adr->in(AddPNode::Base);
1854 if ((base != NULL) && base->is_DecodeN()) {
1855 // Get LoadN node which loads IntegerCache.cache field
1856 base = base->in(1);
1857 }
1858 if ((base != NULL) && base->is_Con()) {
1859 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1860 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1861 // It could be narrow oop
1862 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1863 }
1864 }
1865 }
1866 #endif
1867 return jt;
1868 }
1869 }
1870 } else if (tp->base() == Type::InstPtr) {
1871 assert( off != Type::OffsetBot ||
1872 // arrays can be cast to Objects
1873 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1874 tp->is_oopptr()->klass() == ciEnv::current()->Class_klass() ||
1875 // unsafe field access may not have a constant offset
1876 C->has_unsafe_access(),
1877 "Field accesses must be precise" );
1878 // For oop loads, we expect the _type to be precise.
1879
1880 const TypeInstPtr* tinst = tp->is_instptr();
1881 BasicType bt = memory_type();
1882
1883 // Fold component and value mirror loads
1884 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1885 if (ik == phase->C->env()->Class_klass() && (off == java_lang_Class::component_mirror_offset_in_bytes() ||
1886 off == java_lang_Class::inline_mirror_offset_in_bytes())) {
1887 ciType* mirror_type = tinst->java_mirror_type();
1888 if (mirror_type != NULL) {
1889 const Type* const_oop = TypePtr::NULL_PTR;
1890 if (mirror_type->is_array_klass()) {
1891 const_oop = TypeInstPtr::make(mirror_type->as_array_klass()->component_mirror_instance());
1892 } else if (mirror_type->is_valuetype()) {
1893 const_oop = TypeInstPtr::make(mirror_type->as_value_klass()->inline_mirror_instance());
1894 }
1895 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
1896 }
1897 }
1898
1899 // Optimize loads from constant fields.
1900 ciObject* const_oop = tinst->const_oop();
1901 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1902 ciType* mirror_type = const_oop->as_instance()->java_mirror_type();
1903 if (mirror_type != NULL && mirror_type->is_valuetype()) {
1904 ciValueKlass* vk = mirror_type->as_value_klass();
1905 if (off == vk->default_value_offset()) {
1906 // Loading a special hidden field that contains the oop of the default value type
1907 const Type* const_oop = TypeInstPtr::make(vk->default_value_instance());
1908 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
1909 }
1910 }
1911 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
1912 if (con_type != NULL) {
1913 return con_type;
1914 }
1915 }
1916 } else if (tp->base() == Type::KlassPtr) {
1917 assert( off != Type::OffsetBot ||
1918 // arrays can be cast to Objects
1919 tp->is_klassptr()->klass() == NULL ||
1920 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1921 // also allow array-loading from the primary supertype
1922 // array during subtype checks
1923 Opcode() == Op_LoadKlass,
1924 "Field accesses must be precise" );
1925 // For klass/static loads, we expect the _type to be precise
1926 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
1927 if (adr->is_Load() && off == 0) {
1928 /* With mirrors being an indirect in the Klass*
1929 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1930 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1931 *
1932 * So check the type and klass of the node before the LoadP.
1933 */
1934 Node* adr2 = adr->in(MemNode::Address);
1935 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1936 if (tkls != NULL) {
1937 ciKlass* klass = tkls->klass();
1938 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1939 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1940 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1941 return TypeInstPtr::make(klass->java_mirror());
1942 }
1943 }
1944 } else {
1945 // Check for a load of the default value offset from the ValueKlassFixedBlock:
1946 // LoadI(LoadP(value_klass, adr_valueklass_fixed_block_offset), default_value_offset_offset)
1947 intptr_t offset = 0;
1948 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1949 if (base != NULL && base->is_Load() && offset == in_bytes(ValueKlass::default_value_offset_offset())) {
1950 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
1951 if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->isa_valuetype() &&
1952 tkls->offset() == in_bytes(InstanceKlass::adr_valueklass_fixed_block_offset())) {
1953 assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
1954 assert(Opcode() == Op_LoadI, "must load an int from fixed block");
1955 return TypeInt::make(tkls->klass()->as_value_klass()->default_value_offset());
1956 }
1957 }
1958 }
1959 }
1960
1961 const TypeKlassPtr *tkls = tp->isa_klassptr();
1962 if (tkls != NULL && !StressReflectiveCode) {
1963 ciKlass* klass = tkls->klass();
1964 if (tkls->is_loaded() && tkls->klass_is_exact()) {
1965 // We are loading a field from a Klass metaobject whose identity
1966 // is known at compile time (the type is "exact" or "precise").
1967 // Check for fields we know are maintained as constants by the VM.
1968 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1969 // The field is Klass::_super_check_offset. Return its (constant) value.
1970 // (Folds up type checking code.)
1971 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1972 return TypeInt::make(klass->super_check_offset());
1973 }
1974 // Compute index into primary_supers array
1975 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1976 // Check for overflowing; use unsigned compare to handle the negative case.
1977 if( depth < ciKlass::primary_super_limit() ) {
1978 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1979 // (Folds up type checking code.)
1980 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1981 ciKlass *ss = klass->super_of_depth(depth);
1982 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1983 }
1984 const Type* aift = load_array_final_field(tkls, klass);
1985 if (aift != NULL) return aift;
1986 }
1987
1988 // We can still check if we are loading from the primary_supers array at a
1989 // shallow enough depth. Even though the klass is not exact, entries less
1990 // than or equal to its super depth are correct.
1991 if (tkls->is_loaded()) {
1992 ciType *inner = klass;
1993 while( inner->is_obj_array_klass() )
1994 inner = inner->as_obj_array_klass()->base_element_type();
1995 if( inner->is_instance_klass() &&
1996 !inner->as_instance_klass()->flags().is_interface() ) {
1997 // Compute index into primary_supers array
1998 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1999 // Check for overflowing; use unsigned compare to handle the negative case.
2000 if( depth < ciKlass::primary_super_limit() &&
2001 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
2002 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2003 // (Folds up type checking code.)
2004 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2005 ciKlass *ss = klass->super_of_depth(depth);
2006 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2007 }
2008 }
2009 }
2010
2011 // If the type is enough to determine that the thing is not an array,
2012 // we can give the layout_helper a positive interval type.
2013 // This will help short-circuit some reflective code.
2014 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
2015 && !klass->is_array_klass() // not directly typed as an array
2016 && !klass->is_interface() // specifically not Serializable & Cloneable
2017 && !klass->is_java_lang_Object() // not the supertype of all T[]
2018 ) {
2019 // Note: When interfaces are reliable, we can narrow the interface
2020 // test to (klass != Serializable && klass != Cloneable).
2021 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2022 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2023 // The key property of this type is that it folds up tests
2024 // for array-ness, since it proves that the layout_helper is positive.
2025 // Thus, a generic value like the basic object layout helper works fine.
2026 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2027 }
2028 }
2029
2030 // If we are loading from a freshly-allocated object, produce a zero,
2031 // if the load is provably beyond the header of the object.
2032 // (Also allow a variable load from a fresh array to produce zero.)
2033 const TypeOopPtr *tinst = tp->isa_oopptr();
2034 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
2035 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
2036 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2037 Node* value = can_see_stored_value(mem,phase);
2038 if (value != NULL && value->is_Con()) {
2039 assert(value->bottom_type()->higher_equal(_type),"sanity");
2040 return value->bottom_type();
2041 }
2042 }
2043
2044 if (is_instance) {
2045 // If we have an instance type and our memory input is the
2046 // programs's initial memory state, there is no matching store,
2047 // so just return a zero of the appropriate type
2048 Node *mem = in(MemNode::Memory);
2049 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2050 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2051 return Type::get_zero_type(_type->basic_type());
2052 }
2053 }
2054
2055 Node* alloc = is_new_object_mark_load(phase);
2056 if (alloc != NULL && !(alloc->Opcode() == Op_Allocate && UseBiasedLocking)) {
2057 return TypeX::make(markWord::prototype().value());
2058 }
2059
2060 return _type;
2061 }
2062
2063 //------------------------------match_edge-------------------------------------
2064 // Do we Match on this edge index or not? Match only the address.
2065 uint LoadNode::match_edge(uint idx) const {
2066 return idx == MemNode::Address;
2067 }
2068
2069 //--------------------------LoadBNode::Ideal--------------------------------------
2070 //
2071 // If the previous store is to the same address as this load,
2072 // and the value stored was larger than a byte, replace this load
2073 // with the value stored truncated to a byte. If no truncation is
2074 // needed, the replacement is done in LoadNode::Identity().
2075 //
2076 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2077 Node* mem = in(MemNode::Memory);
2078 Node* value = can_see_stored_value(mem,phase);
2079 if( value && !phase->type(value)->higher_equal( _type ) ) {
2080 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
2081 return new RShiftINode(result, phase->intcon(24));
2082 }
2083 // Identity call will handle the case where truncation is not needed.
2084 return LoadNode::Ideal(phase, can_reshape);
2085 }
2086
2087 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2088 Node* mem = in(MemNode::Memory);
2089 Node* value = can_see_stored_value(mem,phase);
2090 if (value != NULL && value->is_Con() &&
2091 !value->bottom_type()->higher_equal(_type)) {
2092 // If the input to the store does not fit with the load's result type,
2093 // it must be truncated. We can't delay until Ideal call since
2094 // a singleton Value is needed for split_thru_phi optimization.
2095 int con = value->get_int();
2096 return TypeInt::make((con << 24) >> 24);
2097 }
2098 return LoadNode::Value(phase);
2099 }
2100
2101 //--------------------------LoadUBNode::Ideal-------------------------------------
2102 //
2103 // If the previous store is to the same address as this load,
2104 // and the value stored was larger than a byte, replace this load
2105 // with the value stored truncated to a byte. If no truncation is
2106 // needed, the replacement is done in LoadNode::Identity().
2107 //
2108 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2109 Node* mem = in(MemNode::Memory);
2110 Node* value = can_see_stored_value(mem, phase);
2111 if (value && !phase->type(value)->higher_equal(_type))
2112 return new AndINode(value, phase->intcon(0xFF));
2113 // Identity call will handle the case where truncation is not needed.
2114 return LoadNode::Ideal(phase, can_reshape);
2115 }
2116
2117 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2118 Node* mem = in(MemNode::Memory);
2119 Node* value = can_see_stored_value(mem,phase);
2120 if (value != NULL && value->is_Con() &&
2121 !value->bottom_type()->higher_equal(_type)) {
2122 // If the input to the store does not fit with the load's result type,
2123 // it must be truncated. We can't delay until Ideal call since
2124 // a singleton Value is needed for split_thru_phi optimization.
2125 int con = value->get_int();
2126 return TypeInt::make(con & 0xFF);
2127 }
2128 return LoadNode::Value(phase);
2129 }
2130
2131 //--------------------------LoadUSNode::Ideal-------------------------------------
2132 //
2133 // If the previous store is to the same address as this load,
2134 // and the value stored was larger than a char, replace this load
2135 // with the value stored truncated to a char. If no truncation is
2136 // needed, the replacement is done in LoadNode::Identity().
2137 //
2138 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2139 Node* mem = in(MemNode::Memory);
2140 Node* value = can_see_stored_value(mem,phase);
2141 if( value && !phase->type(value)->higher_equal( _type ) )
2142 return new AndINode(value,phase->intcon(0xFFFF));
2143 // Identity call will handle the case where truncation is not needed.
2144 return LoadNode::Ideal(phase, can_reshape);
2145 }
2146
2147 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2148 Node* mem = in(MemNode::Memory);
2149 Node* value = can_see_stored_value(mem,phase);
2150 if (value != NULL && value->is_Con() &&
2151 !value->bottom_type()->higher_equal(_type)) {
2152 // If the input to the store does not fit with the load's result type,
2153 // it must be truncated. We can't delay until Ideal call since
2154 // a singleton Value is needed for split_thru_phi optimization.
2155 int con = value->get_int();
2156 return TypeInt::make(con & 0xFFFF);
2157 }
2158 return LoadNode::Value(phase);
2159 }
2160
2161 //--------------------------LoadSNode::Ideal--------------------------------------
2162 //
2163 // If the previous store is to the same address as this load,
2164 // and the value stored was larger than a short, replace this load
2165 // with the value stored truncated to a short. If no truncation is
2166 // needed, the replacement is done in LoadNode::Identity().
2167 //
2168 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2169 Node* mem = in(MemNode::Memory);
2170 Node* value = can_see_stored_value(mem,phase);
2171 if( value && !phase->type(value)->higher_equal( _type ) ) {
2172 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2173 return new RShiftINode(result, phase->intcon(16));
2174 }
2175 // Identity call will handle the case where truncation is not needed.
2176 return LoadNode::Ideal(phase, can_reshape);
2177 }
2178
2179 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2180 Node* mem = in(MemNode::Memory);
2181 Node* value = can_see_stored_value(mem,phase);
2182 if (value != NULL && value->is_Con() &&
2183 !value->bottom_type()->higher_equal(_type)) {
2184 // If the input to the store does not fit with the load's result type,
2185 // it must be truncated. We can't delay until Ideal call since
2186 // a singleton Value is needed for split_thru_phi optimization.
2187 int con = value->get_int();
2188 return TypeInt::make((con << 16) >> 16);
2189 }
2190 return LoadNode::Value(phase);
2191 }
2192
2193 //=============================================================================
2194 //----------------------------LoadKlassNode::make------------------------------
2195 // Polymorphic factory method:
2196 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
2197 const TypeKlassPtr* tk, bool clear_prop_bits) {
2198 // sanity check the alias category against the created node type
2199 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2200 assert(adr_type != NULL, "expecting TypeKlassPtr");
2201 #ifdef _LP64
2202 if (adr_type->is_ptr_to_narrowklass()) {
2203 assert(UseCompressedClassPointers, "no compressed klasses");
2204 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered, clear_prop_bits));
2205 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2206 }
2207 #endif
2208 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2209 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered, clear_prop_bits);
2210 }
2211
2212 //------------------------------Value------------------------------------------
2213 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2214 return klass_value_common(phase);
2215 }
2216
2217 // In most cases, LoadKlassNode does not have the control input set. If the control
2218 // input is set, it must not be removed (by LoadNode::Ideal()).
2219 bool LoadKlassNode::can_remove_control() const {
2220 return false;
2221 }
2222
2223 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2224 // Either input is TOP ==> the result is TOP
2225 const Type *t1 = phase->type( in(MemNode::Memory) );
2226 if (t1 == Type::TOP) return Type::TOP;
2227 Node *adr = in(MemNode::Address);
2228 const Type *t2 = phase->type( adr );
2229 if (t2 == Type::TOP) return Type::TOP;
2230 const TypePtr *tp = t2->is_ptr();
2231 if (TypePtr::above_centerline(tp->ptr()) ||
2232 tp->ptr() == TypePtr::Null) return Type::TOP;
2233
2234 // Return a more precise klass, if possible
2235 const TypeInstPtr *tinst = tp->isa_instptr();
2236 if (tinst != NULL) {
2237 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2238 int offset = tinst->offset();
2239 if (ik == phase->C->env()->Class_klass()
2240 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2241 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2242 // We are loading a special hidden field from a Class mirror object,
2243 // the field which points to the VM's Klass metaobject.
2244 bool is_indirect_type = true;
2245 ciType* t = tinst->java_mirror_type(&is_indirect_type);
2246 // java_mirror_type returns non-null for compile-time Class constants.
2247 if (t != NULL) {
2248 // constant oop => constant klass
2249 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2250 if (t->is_void()) {
2251 // We cannot create a void array. Since void is a primitive type return null
2252 // klass. Users of this result need to do a null check on the returned klass.
2253 return TypePtr::NULL_PTR;
2254 }
2255 return TypeKlassPtr::make(ciArrayKlass::make(t, /* never_null */ !is_indirect_type));
2256 }
2257 if (!t->is_klass()) {
2258 // a primitive Class (e.g., int.class) has NULL for a klass field
2259 return TypePtr::NULL_PTR;
2260 }
2261 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2262 return TypeKlassPtr::make(t->as_klass());
2263 }
2264 // non-constant mirror, so we can't tell what's going on
2265 }
2266 if( !ik->is_loaded() )
2267 return _type; // Bail out if not loaded
2268 if (offset == oopDesc::klass_offset_in_bytes()) {
2269 if (tinst->klass_is_exact()) {
2270 return TypeKlassPtr::make(ik);
2271 }
2272 // See if we can become precise: no subklasses and no interface
2273 // (Note: We need to support verified interfaces.)
2274 if (!ik->is_interface() && !ik->has_subklass()) {
2275 //assert(!UseExactTypes, "this code should be useless with exact types");
2276 // Add a dependence; if any subclass added we need to recompile
2277 if (!ik->is_final()) {
2278 // %%% should use stronger assert_unique_concrete_subtype instead
2279 phase->C->dependencies()->assert_leaf_type(ik);
2280 }
2281 // Return precise klass
2282 return TypeKlassPtr::make(ik);
2283 }
2284
2285 // Return root of possible klass
2286 return TypeKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0), tinst->flat_array());
2287 }
2288 }
2289
2290 // Check for loading klass from an array
2291 const TypeAryPtr *tary = tp->isa_aryptr();
2292 if (tary != NULL) {
2293 ciKlass *tary_klass = tary->klass();
2294 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2295 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2296 ciArrayKlass* ak = tary_klass->as_array_klass();
2297 // Do not fold klass loads from [V?. The runtime type might be [V due to [V <: [V?
2298 // and the klass for [V is not equal to the klass for [V?.
2299 if (tary->klass_is_exact()) {
2300 return TypeKlassPtr::make(tary_klass);
2301 }
2302
2303 // If the klass is an object array, we defer the question to the
2304 // array component klass.
2305 if (ak->is_obj_array_klass()) {
2306 assert(ak->is_loaded(), "");
2307 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2308 if (base_k->is_loaded() && base_k->is_instance_klass()) {
2309 ciInstanceKlass *ik = base_k->as_instance_klass();
2310 // See if we can become precise: no subklasses and no interface
2311 if (!ik->is_interface() && !ik->has_subklass() && (!ik->is_valuetype() || ak->storage_properties().is_null_free())) {
2312 //assert(!UseExactTypes, "this code should be useless with exact types");
2313 // Add a dependence; if any subclass added we need to recompile
2314 if (!ik->is_final()) {
2315 phase->C->dependencies()->assert_leaf_type(ik);
2316 }
2317 // Return precise array klass
2318 return TypeKlassPtr::make(ak);
2319 }
2320 }
2321 return TypeKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0), false);
2322 } else if (ak->is_type_array_klass()) {
2323 //assert(!UseExactTypes, "this code should be useless with exact types");
2324 return TypeKlassPtr::make(ak); // These are always precise
2325 }
2326 }
2327 }
2328
2329 // Check for loading klass from an array klass
2330 const TypeKlassPtr *tkls = tp->isa_klassptr();
2331 if (tkls != NULL && !StressReflectiveCode) {
2332 if (!tkls->is_loaded()) {
2333 return _type; // Bail out if not loaded
2334 }
2335 ciKlass* klass = tkls->klass();
2336 if( klass->is_obj_array_klass() &&
2337 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2338 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2339 // // Always returning precise element type is incorrect,
2340 // // e.g., element type could be object and array may contain strings
2341 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2342
2343 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2344 // according to the element type's subclassing.
2345 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0), elem->flatten_array());
2346 } else if (klass->is_value_array_klass() &&
2347 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2348 ciKlass* elem = klass->as_value_array_klass()->element_klass();
2349 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0), true);
2350 }
2351 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2352 tkls->offset() == in_bytes(Klass::super_offset())) {
2353 ciKlass* sup = klass->as_instance_klass()->super();
2354 // The field is Klass::_super. Return its (constant) value.
2355 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2356 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2357 }
2358 }
2359
2360 // Bailout case
2361 return LoadNode::Value(phase);
2362 }
2363
2364 //------------------------------Identity---------------------------------------
2365 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2366 // Also feed through the klass in Allocate(...klass...)._klass.
2367 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2368 return klass_identity_common(phase);
2369 }
2370
2371 const Type* GetStoragePropertyNode::Value(PhaseGVN* phase) const {
2372 if (in(1) != NULL) {
2373 const Type* in1_t = phase->type(in(1));
2374 if (in1_t == Type::TOP) {
2375 return Type::TOP;
2376 }
2377 const TypeKlassPtr* tk = in1_t->make_ptr()->is_klassptr();
2378 ciArrayKlass* ak = tk->klass()->as_array_klass();
2379 ciKlass* elem = ak->element_klass();
2380 if (tk->klass_is_exact() || (!elem->is_java_lang_Object() && !elem->is_interface() && !elem->is_valuetype())) {
2381 int props_shift = in1_t->isa_narrowklass() ? oopDesc::narrow_storage_props_shift : oopDesc::wide_storage_props_shift;
2382 ArrayStorageProperties props = ak->storage_properties();
2383 intptr_t storage_properties = 0;
2384 if ((Opcode() == Op_GetFlattenedProperty && props.is_flattened()) ||
2385 (Opcode() == Op_GetNullFreeProperty && props.is_null_free())) {
2386 storage_properties = 1;
2387 }
2388 if (in1_t->isa_narrowklass()) {
2389 return TypeInt::make((int)storage_properties);
2390 }
2391 return TypeX::make(storage_properties);
2392 }
2393 }
2394 return bottom_type();
2395 }
2396
2397 Node* GetStoragePropertyNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2398 if (!can_reshape) {
2399 return NULL;
2400 }
2401 if (in(1) != NULL && in(1)->is_Phi()) {
2402 Node* phi = in(1);
2403 Node* r = phi->in(0);
2404 Node* new_phi = new PhiNode(r, bottom_type());
2405 for (uint i = 1; i < r->req(); i++) {
2406 Node* in = phi->in(i);
2407 if (in == NULL) continue;
2408 Node* n = clone();
2409 n->set_req(1, in);
2410 new_phi->init_req(i, phase->transform(n));
2411 }
2412 return new_phi;
2413 }
2414 return NULL;
2415 }
2416
2417 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2418 Node* x = LoadNode::Identity(phase);
2419 if (x != this) return x;
2420
2421 // Take apart the address into an oop and and offset.
2422 // Return 'this' if we cannot.
2423 Node* adr = in(MemNode::Address);
2424 intptr_t offset = 0;
2425 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2426 if (base == NULL) return this;
2427 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2428 if (toop == NULL) return this;
2429
2430 // Step over potential GC barrier for OopHandle resolve
2431 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2432 if (bs->is_gc_barrier_node(base)) {
2433 base = bs->step_over_gc_barrier(base);
2434 }
2435
2436 // We can fetch the klass directly through an AllocateNode.
2437 // This works even if the klass is not constant (clone or newArray).
2438 if (offset == oopDesc::klass_offset_in_bytes()) {
2439 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2440 if (allocated_klass != NULL) {
2441 return allocated_klass;
2442 }
2443 }
2444
2445 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2446 // See inline_native_Class_query for occurrences of these patterns.
2447 // Java Example: x.getClass().isAssignableFrom(y)
2448 //
2449 // This improves reflective code, often making the Class
2450 // mirror go completely dead. (Current exception: Class
2451 // mirrors may appear in debug info, but we could clean them out by
2452 // introducing a new debug info operator for Klass.java_mirror).
2453
2454 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2455 && offset == java_lang_Class::klass_offset_in_bytes()) {
2456 if (base->is_Load()) {
2457 Node* base2 = base->in(MemNode::Address);
2458 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2459 Node* adr2 = base2->in(MemNode::Address);
2460 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2461 if (tkls != NULL && !tkls->empty()
2462 && (tkls->klass()->is_instance_klass() ||
2463 tkls->klass()->is_array_klass())
2464 && adr2->is_AddP()
2465 ) {
2466 int mirror_field = in_bytes(Klass::java_mirror_offset());
2467 if (tkls->offset() == mirror_field) {
2468 return adr2->in(AddPNode::Base);
2469 }
2470 }
2471 }
2472 }
2473 }
2474
2475 return this;
2476 }
2477
2478
2479 //------------------------------Value------------------------------------------
2480 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2481 const Type *t = klass_value_common(phase);
2482 if (t == Type::TOP)
2483 return t;
2484
2485 return t->make_narrowklass();
2486 }
2487
2488 //------------------------------Identity---------------------------------------
2489 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2490 // Also feed through the klass in Allocate(...klass...)._klass.
2491 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2492 Node *x = klass_identity_common(phase);
2493
2494 const Type *t = phase->type( x );
2495 if( t == Type::TOP ) return x;
2496 if( t->isa_narrowklass()) return x;
2497 assert (!t->isa_narrowoop(), "no narrow oop here");
2498
2499 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2500 }
2501
2502 //------------------------------Value-----------------------------------------
2503 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2504 // Either input is TOP ==> the result is TOP
2505 const Type *t1 = phase->type( in(MemNode::Memory) );
2506 if( t1 == Type::TOP ) return Type::TOP;
2507 Node *adr = in(MemNode::Address);
2508 const Type *t2 = phase->type( adr );
2509 if( t2 == Type::TOP ) return Type::TOP;
2510 const TypePtr *tp = t2->is_ptr();
2511 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2512 const TypeAryPtr *tap = tp->isa_aryptr();
2513 if( !tap ) return _type;
2514 return tap->size();
2515 }
2516
2517 //-------------------------------Ideal---------------------------------------
2518 // Feed through the length in AllocateArray(...length...)._length.
2519 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2520 Node* p = MemNode::Ideal_common(phase, can_reshape);
2521 if (p) return (p == NodeSentinel) ? NULL : p;
2522
2523 // Take apart the address into an oop and and offset.
2524 // Return 'this' if we cannot.
2525 Node* adr = in(MemNode::Address);
2526 intptr_t offset = 0;
2527 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2528 if (base == NULL) return NULL;
2529 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2530 if (tary == NULL) return NULL;
2531
2532 // We can fetch the length directly through an AllocateArrayNode.
2533 // This works even if the length is not constant (clone or newArray).
2534 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2535 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2536 if (alloc != NULL) {
2537 Node* allocated_length = alloc->Ideal_length();
2538 Node* len = alloc->make_ideal_length(tary, phase);
2539 if (allocated_length != len) {
2540 // New CastII improves on this.
2541 return len;
2542 }
2543 }
2544 }
2545
2546 return NULL;
2547 }
2548
2549 //------------------------------Identity---------------------------------------
2550 // Feed through the length in AllocateArray(...length...)._length.
2551 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2552 Node* x = LoadINode::Identity(phase);
2553 if (x != this) return x;
2554
2555 // Take apart the address into an oop and and offset.
2556 // Return 'this' if we cannot.
2557 Node* adr = in(MemNode::Address);
2558 intptr_t offset = 0;
2559 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2560 if (base == NULL) return this;
2561 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2562 if (tary == NULL) return this;
2563
2564 // We can fetch the length directly through an AllocateArrayNode.
2565 // This works even if the length is not constant (clone or newArray).
2566 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2567 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2568 if (alloc != NULL) {
2569 Node* allocated_length = alloc->Ideal_length();
2570 // Do not allow make_ideal_length to allocate a CastII node.
2571 Node* len = alloc->make_ideal_length(tary, phase, false);
2572 if (allocated_length == len) {
2573 // Return allocated_length only if it would not be improved by a CastII.
2574 return allocated_length;
2575 }
2576 }
2577 }
2578
2579 return this;
2580
2581 }
2582
2583 //=============================================================================
2584 //---------------------------StoreNode::make-----------------------------------
2585 // Polymorphic factory method:
2586 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2587 assert((mo == unordered || mo == release), "unexpected");
2588 Compile* C = gvn.C;
2589 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2590 ctl != NULL, "raw memory operations should have control edge");
2591
2592 switch (bt) {
2593 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2594 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2595 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2596 case T_CHAR:
2597 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2598 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2599 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2600 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2601 case T_METADATA:
2602 case T_ADDRESS:
2603 case T_VALUETYPE:
2604 case T_OBJECT:
2605 #ifdef _LP64
2606 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2607 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2608 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2609 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2610 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2611 adr->bottom_type()->isa_rawptr())) {
2612 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2613 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2614 }
2615 #endif
2616 {
2617 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2618 }
2619 default:
2620 ShouldNotReachHere();
2621 return (StoreNode*)NULL;
2622 }
2623 }
2624
2625 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2626 bool require_atomic = true;
2627 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2628 }
2629
2630 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2631 bool require_atomic = true;
2632 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2633 }
2634
2635
2636 //--------------------------bottom_type----------------------------------------
2637 const Type *StoreNode::bottom_type() const {
2638 return Type::MEMORY;
2639 }
2640
2641 //------------------------------hash-------------------------------------------
2642 uint StoreNode::hash() const {
2643 // unroll addition of interesting fields
2644 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2645
2646 // Since they are not commoned, do not hash them:
2647 return NO_HASH;
2648 }
2649
2650 //------------------------------Ideal------------------------------------------
2651 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2652 // When a store immediately follows a relevant allocation/initialization,
2653 // try to capture it into the initialization, or hoist it above.
2654 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2655 Node* p = MemNode::Ideal_common(phase, can_reshape);
2656 if (p) return (p == NodeSentinel) ? NULL : p;
2657
2658 Node* mem = in(MemNode::Memory);
2659 Node* address = in(MemNode::Address);
2660 // Back-to-back stores to same address? Fold em up. Generally
2661 // unsafe if I have intervening uses... Also disallowed for StoreCM
2662 // since they must follow each StoreP operation. Redundant StoreCMs
2663 // are eliminated just before matching in final_graph_reshape.
2664 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::VALUES) {
2665 Node* st = mem;
2666 // If Store 'st' has more than one use, we cannot fold 'st' away.
2667 // For example, 'st' might be the final state at a conditional
2668 // return. Or, 'st' might be used by some node which is live at
2669 // the same time 'st' is live, which might be unschedulable. So,
2670 // require exactly ONE user until such time as we clone 'mem' for
2671 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2672 // true).
2673 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2674 // Looking at a dead closed cycle of memory?
2675 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2676 assert(Opcode() == st->Opcode() ||
2677 st->Opcode() == Op_StoreVector ||
2678 Opcode() == Op_StoreVector ||
2679 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2680 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2681 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2682 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2683 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2684 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2685
2686 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2687 st->as_Store()->memory_size() <= this->memory_size()) {
2688 Node* use = st->raw_out(0);
2689 phase->igvn_rehash_node_delayed(use);
2690 if (can_reshape) {
2691 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2692 } else {
2693 // It's OK to do this in the parser, since DU info is always accurate,
2694 // and the parser always refers to nodes via SafePointNode maps.
2695 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2696 }
2697 return this;
2698 }
2699 st = st->in(MemNode::Memory);
2700 }
2701 }
2702
2703
2704 // Capture an unaliased, unconditional, simple store into an initializer.
2705 // Or, if it is independent of the allocation, hoist it above the allocation.
2706 if (ReduceFieldZeroing && /*can_reshape &&*/
2707 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2708 InitializeNode* init = mem->in(0)->as_Initialize();
2709 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2710 if (offset > 0) {
2711 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2712 // If the InitializeNode captured me, it made a raw copy of me,
2713 // and I need to disappear.
2714 if (moved != NULL) {
2715 // %%% hack to ensure that Ideal returns a new node:
2716 mem = MergeMemNode::make(mem);
2717 return mem; // fold me away
2718 }
2719 }
2720 }
2721
2722 return NULL; // No further progress
2723 }
2724
2725 //------------------------------Value-----------------------------------------
2726 const Type* StoreNode::Value(PhaseGVN* phase) const {
2727 // Either input is TOP ==> the result is TOP
2728 const Type *t1 = phase->type( in(MemNode::Memory) );
2729 if( t1 == Type::TOP ) return Type::TOP;
2730 const Type *t2 = phase->type( in(MemNode::Address) );
2731 if( t2 == Type::TOP ) return Type::TOP;
2732 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2733 if( t3 == Type::TOP ) return Type::TOP;
2734 return Type::MEMORY;
2735 }
2736
2737 //------------------------------Identity---------------------------------------
2738 // Remove redundant stores:
2739 // Store(m, p, Load(m, p)) changes to m.
2740 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2741 Node* StoreNode::Identity(PhaseGVN* phase) {
2742 Node* mem = in(MemNode::Memory);
2743 Node* adr = in(MemNode::Address);
2744 Node* val = in(MemNode::ValueIn);
2745
2746 Node* result = this;
2747
2748 // Load then Store? Then the Store is useless
2749 if (val->is_Load() &&
2750 val->in(MemNode::Address)->eqv_uncast(adr) &&
2751 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2752 val->as_Load()->store_Opcode() == Opcode()) {
2753 result = mem;
2754 }
2755
2756 // Two stores in a row of the same value?
2757 if (result == this &&
2758 mem->is_Store() &&
2759 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2760 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2761 mem->Opcode() == Opcode()) {
2762 result = mem;
2763 }
2764
2765 // Store of zero anywhere into a freshly-allocated object?
2766 // Then the store is useless.
2767 // (It must already have been captured by the InitializeNode.)
2768 if (result == this && ReduceFieldZeroing) {
2769 // a newly allocated object is already all-zeroes everywhere
2770 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2771 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2772 assert(!phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == NULL, "storing null to value array is forbidden");
2773 result = mem;
2774 }
2775
2776 if (result == this) {
2777 // the store may also apply to zero-bits in an earlier object
2778 Node* prev_mem = find_previous_store(phase);
2779 // Steps (a), (b): Walk past independent stores to find an exact match.
2780 if (prev_mem != NULL) {
2781 Node* prev_val = can_see_stored_value(prev_mem, phase);
2782 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2783 // prev_val and val might differ by a cast; it would be good
2784 // to keep the more informative of the two.
2785 if (phase->type(val)->is_zero_type()) {
2786 result = mem;
2787 } else if (prev_mem->is_Proj() && prev_mem->in(0)->is_Initialize()) {
2788 InitializeNode* init = prev_mem->in(0)->as_Initialize();
2789 AllocateNode* alloc = init->allocation();
2790 if (alloc != NULL && alloc->in(AllocateNode::DefaultValue) == val) {
2791 result = mem;
2792 }
2793 }
2794 }
2795 }
2796 }
2797 }
2798
2799 if (result != this && phase->is_IterGVN() != NULL) {
2800 MemBarNode* trailing = trailing_membar();
2801 if (trailing != NULL) {
2802 #ifdef ASSERT
2803 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2804 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2805 #endif
2806 PhaseIterGVN* igvn = phase->is_IterGVN();
2807 trailing->remove(igvn);
2808 }
2809 }
2810
2811 return result;
2812 }
2813
2814 //------------------------------match_edge-------------------------------------
2815 // Do we Match on this edge index or not? Match only memory & value
2816 uint StoreNode::match_edge(uint idx) const {
2817 return idx == MemNode::Address || idx == MemNode::ValueIn;
2818 }
2819
2820 //------------------------------cmp--------------------------------------------
2821 // Do not common stores up together. They generally have to be split
2822 // back up anyways, so do not bother.
2823 bool StoreNode::cmp( const Node &n ) const {
2824 return (&n == this); // Always fail except on self
2825 }
2826
2827 //------------------------------Ideal_masked_input-----------------------------
2828 // Check for a useless mask before a partial-word store
2829 // (StoreB ... (AndI valIn conIa) )
2830 // If (conIa & mask == mask) this simplifies to
2831 // (StoreB ... (valIn) )
2832 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2833 Node *val = in(MemNode::ValueIn);
2834 if( val->Opcode() == Op_AndI ) {
2835 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2836 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2837 set_req(MemNode::ValueIn, val->in(1));
2838 return this;
2839 }
2840 }
2841 return NULL;
2842 }
2843
2844
2845 //------------------------------Ideal_sign_extended_input----------------------
2846 // Check for useless sign-extension before a partial-word store
2847 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2848 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2849 // (StoreB ... (valIn) )
2850 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2851 Node *val = in(MemNode::ValueIn);
2852 if( val->Opcode() == Op_RShiftI ) {
2853 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2854 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2855 Node *shl = val->in(1);
2856 if( shl->Opcode() == Op_LShiftI ) {
2857 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2858 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2859 set_req(MemNode::ValueIn, shl->in(1));
2860 return this;
2861 }
2862 }
2863 }
2864 }
2865 return NULL;
2866 }
2867
2868 //------------------------------value_never_loaded-----------------------------------
2869 // Determine whether there are any possible loads of the value stored.
2870 // For simplicity, we actually check if there are any loads from the
2871 // address stored to, not just for loads of the value stored by this node.
2872 //
2873 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2874 Node *adr = in(Address);
2875 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2876 if (adr_oop == NULL)
2877 return false;
2878 if (!adr_oop->is_known_instance_field())
2879 return false; // if not a distinct instance, there may be aliases of the address
2880 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2881 Node *use = adr->fast_out(i);
2882 if (use->is_Load() || use->is_LoadStore()) {
2883 return false;
2884 }
2885 }
2886 return true;
2887 }
2888
2889 MemBarNode* StoreNode::trailing_membar() const {
2890 if (is_release()) {
2891 MemBarNode* trailing_mb = NULL;
2892 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2893 Node* u = fast_out(i);
2894 if (u->is_MemBar()) {
2895 if (u->as_MemBar()->trailing_store()) {
2896 assert(u->Opcode() == Op_MemBarVolatile, "");
2897 assert(trailing_mb == NULL, "only one");
2898 trailing_mb = u->as_MemBar();
2899 #ifdef ASSERT
2900 Node* leading = u->as_MemBar()->leading_membar();
2901 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2902 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2903 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2904 #endif
2905 } else {
2906 assert(u->as_MemBar()->standalone(), "");
2907 }
2908 }
2909 }
2910 return trailing_mb;
2911 }
2912 return NULL;
2913 }
2914
2915
2916 //=============================================================================
2917 //------------------------------Ideal------------------------------------------
2918 // If the store is from an AND mask that leaves the low bits untouched, then
2919 // we can skip the AND operation. If the store is from a sign-extension
2920 // (a left shift, then right shift) we can skip both.
2921 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2922 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2923 if( progress != NULL ) return progress;
2924
2925 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2926 if( progress != NULL ) return progress;
2927
2928 // Finally check the default case
2929 return StoreNode::Ideal(phase, can_reshape);
2930 }
2931
2932 //=============================================================================
2933 //------------------------------Ideal------------------------------------------
2934 // If the store is from an AND mask that leaves the low bits untouched, then
2935 // we can skip the AND operation
2936 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2937 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2938 if( progress != NULL ) return progress;
2939
2940 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2941 if( progress != NULL ) return progress;
2942
2943 // Finally check the default case
2944 return StoreNode::Ideal(phase, can_reshape);
2945 }
2946
2947 //=============================================================================
2948 //------------------------------Identity---------------------------------------
2949 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2950 // No need to card mark when storing a null ptr
2951 Node* my_store = in(MemNode::OopStore);
2952 if (my_store->is_Store()) {
2953 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2954 if( t1 == TypePtr::NULL_PTR ) {
2955 return in(MemNode::Memory);
2956 }
2957 }
2958 return this;
2959 }
2960
2961 //=============================================================================
2962 //------------------------------Ideal---------------------------------------
2963 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2964 Node* progress = StoreNode::Ideal(phase, can_reshape);
2965 if (progress != NULL) return progress;
2966
2967 Node* my_store = in(MemNode::OopStore);
2968 if (my_store->is_MergeMem()) {
2969 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2970 set_req(MemNode::OopStore, mem);
2971 return this;
2972 }
2973
2974 return NULL;
2975 }
2976
2977 //------------------------------Value-----------------------------------------
2978 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2979 // Either input is TOP ==> the result is TOP
2980 const Type *t = phase->type( in(MemNode::Memory) );
2981 if( t == Type::TOP ) return Type::TOP;
2982 t = phase->type( in(MemNode::Address) );
2983 if( t == Type::TOP ) return Type::TOP;
2984 t = phase->type( in(MemNode::ValueIn) );
2985 if( t == Type::TOP ) return Type::TOP;
2986 // If extra input is TOP ==> the result is TOP
2987 t = phase->type( in(MemNode::OopStore) );
2988 if( t == Type::TOP ) return Type::TOP;
2989
2990 return StoreNode::Value( phase );
2991 }
2992
2993
2994 //=============================================================================
2995 //----------------------------------SCMemProjNode------------------------------
2996 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2997 {
2998 return bottom_type();
2999 }
3000
3001 //=============================================================================
3002 //----------------------------------LoadStoreNode------------------------------
3003 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3004 : Node(required),
3005 _type(rt),
3006 _adr_type(at),
3007 _barrier(0)
3008 {
3009 init_req(MemNode::Control, c );
3010 init_req(MemNode::Memory , mem);
3011 init_req(MemNode::Address, adr);
3012 init_req(MemNode::ValueIn, val);
3013 init_class_id(Class_LoadStore);
3014 }
3015
3016 uint LoadStoreNode::ideal_reg() const {
3017 return _type->ideal_reg();
3018 }
3019
3020 bool LoadStoreNode::result_not_used() const {
3021 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3022 Node *x = fast_out(i);
3023 if (x->Opcode() == Op_SCMemProj) continue;
3024 return false;
3025 }
3026 return true;
3027 }
3028
3029 MemBarNode* LoadStoreNode::trailing_membar() const {
3030 MemBarNode* trailing = NULL;
3031 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3032 Node* u = fast_out(i);
3033 if (u->is_MemBar()) {
3034 if (u->as_MemBar()->trailing_load_store()) {
3035 assert(u->Opcode() == Op_MemBarAcquire, "");
3036 assert(trailing == NULL, "only one");
3037 trailing = u->as_MemBar();
3038 #ifdef ASSERT
3039 Node* leading = trailing->leading_membar();
3040 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3041 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3042 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3043 #endif
3044 } else {
3045 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3046 }
3047 }
3048 }
3049
3050 return trailing;
3051 }
3052
3053 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3054
3055 //=============================================================================
3056 //----------------------------------LoadStoreConditionalNode--------------------
3057 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
3058 init_req(ExpectedIn, ex );
3059 }
3060
3061 //=============================================================================
3062 //-------------------------------adr_type--------------------------------------
3063 const TypePtr* ClearArrayNode::adr_type() const {
3064 Node *adr = in(3);
3065 if (adr == NULL) return NULL; // node is dead
3066 return MemNode::calculate_adr_type(adr->bottom_type());
3067 }
3068
3069 //------------------------------match_edge-------------------------------------
3070 // Do we Match on this edge index or not? Do not match memory
3071 uint ClearArrayNode::match_edge(uint idx) const {
3072 return idx > 1;
3073 }
3074
3075 //------------------------------Identity---------------------------------------
3076 // Clearing a zero length array does nothing
3077 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3078 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3079 }
3080
3081 //------------------------------Idealize---------------------------------------
3082 // Clearing a short array is faster with stores
3083 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3084 // Already know this is a large node, do not try to ideal it
3085 if (!IdealizeClearArrayNode || _is_large) return NULL;
3086
3087 const int unit = BytesPerLong;
3088 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3089 if (!t) return NULL;
3090 if (!t->is_con()) return NULL;
3091 intptr_t raw_count = t->get_con();
3092 intptr_t size = raw_count;
3093 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3094 // Clearing nothing uses the Identity call.
3095 // Negative clears are possible on dead ClearArrays
3096 // (see jck test stmt114.stmt11402.val).
3097 if (size <= 0 || size % unit != 0) return NULL;
3098 intptr_t count = size / unit;
3099 // Length too long; communicate this to matchers and assemblers.
3100 // Assemblers are responsible to produce fast hardware clears for it.
3101 if (size > InitArrayShortSize) {
3102 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
3103 }
3104 Node *mem = in(1);
3105 if( phase->type(mem)==Type::TOP ) return NULL;
3106 Node *adr = in(3);
3107 const Type* at = phase->type(adr);
3108 if( at==Type::TOP ) return NULL;
3109 const TypePtr* atp = at->isa_ptr();
3110 // adjust atp to be the correct array element address type
3111 if (atp == NULL) atp = TypePtr::BOTTOM;
3112 else atp = atp->add_offset(Type::OffsetBot);
3113 // Get base for derived pointer purposes
3114 if( adr->Opcode() != Op_AddP ) Unimplemented();
3115 Node *base = adr->in(1);
3116
3117 Node *val = in(4);
3118 Node *off = phase->MakeConX(BytesPerLong);
3119 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3120 count--;
3121 while( count-- ) {
3122 mem = phase->transform(mem);
3123 adr = phase->transform(new AddPNode(base,adr,off));
3124 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3125 }
3126 return mem;
3127 }
3128
3129 //----------------------------step_through----------------------------------
3130 // Return allocation input memory edge if it is different instance
3131 // or itself if it is the one we are looking for.
3132 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3133 Node* n = *np;
3134 assert(n->is_ClearArray(), "sanity");
3135 intptr_t offset;
3136 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3137 // This method is called only before Allocate nodes are expanded
3138 // during macro nodes expansion. Before that ClearArray nodes are
3139 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3140 // Allocate nodes are expanded) which follows allocations.
3141 assert(alloc != NULL, "should have allocation");
3142 if (alloc->_idx == instance_id) {
3143 // Can not bypass initialization of the instance we are looking for.
3144 return false;
3145 }
3146 // Otherwise skip it.
3147 InitializeNode* init = alloc->initialization();
3148 if (init != NULL)
3149 *np = init->in(TypeFunc::Memory);
3150 else
3151 *np = alloc->in(TypeFunc::Memory);
3152 return true;
3153 }
3154
3155 //----------------------------clear_memory-------------------------------------
3156 // Generate code to initialize object storage to zero.
3157 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3158 Node* val,
3159 Node* raw_val,
3160 intptr_t start_offset,
3161 Node* end_offset,
3162 PhaseGVN* phase) {
3163 intptr_t offset = start_offset;
3164
3165 int unit = BytesPerLong;
3166 if ((offset % unit) != 0) {
3167 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3168 adr = phase->transform(adr);
3169 const TypePtr* atp = TypeRawPtr::BOTTOM;
3170 if (val != NULL) {
3171 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3172 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3173 } else {
3174 assert(raw_val == NULL, "val may not be null");
3175 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3176 }
3177 mem = phase->transform(mem);
3178 offset += BytesPerInt;
3179 }
3180 assert((offset % unit) == 0, "");
3181
3182 // Initialize the remaining stuff, if any, with a ClearArray.
3183 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3184 }
3185
3186 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3187 Node* raw_val,
3188 Node* start_offset,
3189 Node* end_offset,
3190 PhaseGVN* phase) {
3191 if (start_offset == end_offset) {
3192 // nothing to do
3193 return mem;
3194 }
3195
3196 int unit = BytesPerLong;
3197 Node* zbase = start_offset;
3198 Node* zend = end_offset;
3199
3200 // Scale to the unit required by the CPU:
3201 if (!Matcher::init_array_count_is_in_bytes) {
3202 Node* shift = phase->intcon(exact_log2(unit));
3203 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3204 zend = phase->transform(new URShiftXNode(zend, shift) );
3205 }
3206
3207 // Bulk clear double-words
3208 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3209 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3210 if (raw_val == NULL) {
3211 raw_val = phase->MakeConX(0);
3212 }
3213 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3214 return phase->transform(mem);
3215 }
3216
3217 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3218 Node* val,
3219 Node* raw_val,
3220 intptr_t start_offset,
3221 intptr_t end_offset,
3222 PhaseGVN* phase) {
3223 if (start_offset == end_offset) {
3224 // nothing to do
3225 return mem;
3226 }
3227
3228 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3229 intptr_t done_offset = end_offset;
3230 if ((done_offset % BytesPerLong) != 0) {
3231 done_offset -= BytesPerInt;
3232 }
3233 if (done_offset > start_offset) {
3234 mem = clear_memory(ctl, mem, dest, val, raw_val,
3235 start_offset, phase->MakeConX(done_offset), phase);
3236 }
3237 if (done_offset < end_offset) { // emit the final 32-bit store
3238 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3239 adr = phase->transform(adr);
3240 const TypePtr* atp = TypeRawPtr::BOTTOM;
3241 if (val != NULL) {
3242 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3243 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3244 } else {
3245 assert(raw_val == NULL, "val may not be null");
3246 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3247 }
3248 mem = phase->transform(mem);
3249 done_offset += BytesPerInt;
3250 }
3251 assert(done_offset == end_offset, "");
3252 return mem;
3253 }
3254
3255 //=============================================================================
3256 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3257 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3258 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3259 #ifdef ASSERT
3260 , _pair_idx(0)
3261 #endif
3262 {
3263 init_class_id(Class_MemBar);
3264 Node* top = C->top();
3265 init_req(TypeFunc::I_O,top);
3266 init_req(TypeFunc::FramePtr,top);
3267 init_req(TypeFunc::ReturnAdr,top);
3268 if (precedent != NULL)
3269 init_req(TypeFunc::Parms, precedent);
3270 }
3271
3272 //------------------------------cmp--------------------------------------------
3273 uint MemBarNode::hash() const { return NO_HASH; }
3274 bool MemBarNode::cmp( const Node &n ) const {
3275 return (&n == this); // Always fail except on self
3276 }
3277
3278 //------------------------------make-------------------------------------------
3279 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3280 switch (opcode) {
3281 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3282 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3283 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3284 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3285 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3286 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3287 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3288 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3289 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3290 case Op_Initialize: return new InitializeNode(C, atp, pn);
3291 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3292 default: ShouldNotReachHere(); return NULL;
3293 }
3294 }
3295
3296 void MemBarNode::remove(PhaseIterGVN *igvn) {
3297 if (outcnt() != 2) {
3298 return;
3299 }
3300 if (trailing_store() || trailing_load_store()) {
3301 MemBarNode* leading = leading_membar();
3302 if (leading != NULL) {
3303 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3304 leading->remove(igvn);
3305 }
3306 }
3307 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3308 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3309 }
3310
3311 //------------------------------Ideal------------------------------------------
3312 // Return a node which is more "ideal" than the current node. Strip out
3313 // control copies
3314 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3315 if (remove_dead_region(phase, can_reshape)) return this;
3316 // Don't bother trying to transform a dead node
3317 if (in(0) && in(0)->is_top()) {
3318 return NULL;
3319 }
3320
3321 bool progress = false;
3322 // Eliminate volatile MemBars for scalar replaced objects.
3323 if (can_reshape && req() == (Precedent+1)) {
3324 bool eliminate = false;
3325 int opc = Opcode();
3326 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3327 // Volatile field loads and stores.
3328 Node* my_mem = in(MemBarNode::Precedent);
3329 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3330 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3331 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3332 // replace this Precedent (decodeN) with the Load instead.
3333 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3334 Node* load_node = my_mem->in(1);
3335 set_req(MemBarNode::Precedent, load_node);
3336 phase->is_IterGVN()->_worklist.push(my_mem);
3337 my_mem = load_node;
3338 } else {
3339 assert(my_mem->unique_out() == this, "sanity");
3340 del_req(Precedent);
3341 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3342 my_mem = NULL;
3343 }
3344 progress = true;
3345 }
3346 if (my_mem != NULL && my_mem->is_Mem()) {
3347 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3348 // Check for scalar replaced object reference.
3349 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3350 t_oop->offset() != Type::OffsetBot &&
3351 t_oop->offset() != Type::OffsetTop) {
3352 eliminate = true;
3353 }
3354 }
3355 } else if (opc == Op_MemBarRelease) {
3356 // Final field stores.
3357 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3358 if ((alloc != NULL) && alloc->is_Allocate() &&
3359 alloc->as_Allocate()->does_not_escape_thread()) {
3360 // The allocated object does not escape.
3361 eliminate = true;
3362 }
3363 }
3364 if (eliminate) {
3365 // Replace MemBar projections by its inputs.
3366 PhaseIterGVN* igvn = phase->is_IterGVN();
3367 remove(igvn);
3368 // Must return either the original node (now dead) or a new node
3369 // (Do not return a top here, since that would break the uniqueness of top.)
3370 return new ConINode(TypeInt::ZERO);
3371 }
3372 }
3373 return progress ? this : NULL;
3374 }
3375
3376 //------------------------------Value------------------------------------------
3377 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3378 if( !in(0) ) return Type::TOP;
3379 if( phase->type(in(0)) == Type::TOP )
3380 return Type::TOP;
3381 return TypeTuple::MEMBAR;
3382 }
3383
3384 //------------------------------match------------------------------------------
3385 // Construct projections for memory.
3386 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3387 switch (proj->_con) {
3388 case TypeFunc::Control:
3389 case TypeFunc::Memory:
3390 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3391 }
3392 ShouldNotReachHere();
3393 return NULL;
3394 }
3395
3396 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3397 trailing->_kind = TrailingStore;
3398 leading->_kind = LeadingStore;
3399 #ifdef ASSERT
3400 trailing->_pair_idx = leading->_idx;
3401 leading->_pair_idx = leading->_idx;
3402 #endif
3403 }
3404
3405 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3406 trailing->_kind = TrailingLoadStore;
3407 leading->_kind = LeadingLoadStore;
3408 #ifdef ASSERT
3409 trailing->_pair_idx = leading->_idx;
3410 leading->_pair_idx = leading->_idx;
3411 #endif
3412 }
3413
3414 MemBarNode* MemBarNode::trailing_membar() const {
3415 ResourceMark rm;
3416 Node* trailing = (Node*)this;
3417 VectorSet seen(Thread::current()->resource_area());
3418 Node_Stack multis(0);
3419 do {
3420 Node* c = trailing;
3421 uint i = 0;
3422 do {
3423 trailing = NULL;
3424 for (; i < c->outcnt(); i++) {
3425 Node* next = c->raw_out(i);
3426 if (next != c && next->is_CFG()) {
3427 if (c->is_MultiBranch()) {
3428 if (multis.node() == c) {
3429 multis.set_index(i+1);
3430 } else {
3431 multis.push(c, i+1);
3432 }
3433 }
3434 trailing = next;
3435 break;
3436 }
3437 }
3438 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3439 break;
3440 }
3441 while (multis.size() > 0) {
3442 c = multis.node();
3443 i = multis.index();
3444 if (i < c->req()) {
3445 break;
3446 }
3447 multis.pop();
3448 }
3449 } while (multis.size() > 0);
3450 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3451
3452 MemBarNode* mb = trailing->as_MemBar();
3453 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3454 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3455 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3456 return mb;
3457 }
3458
3459 MemBarNode* MemBarNode::leading_membar() const {
3460 ResourceMark rm;
3461 VectorSet seen(Thread::current()->resource_area());
3462 Node_Stack regions(0);
3463 Node* leading = in(0);
3464 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3465 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3466 leading = NULL;
3467 while (regions.size() > 0 && leading == NULL) {
3468 Node* r = regions.node();
3469 uint i = regions.index();
3470 if (i < r->req()) {
3471 leading = r->in(i);
3472 regions.set_index(i+1);
3473 } else {
3474 regions.pop();
3475 }
3476 }
3477 if (leading == NULL) {
3478 assert(regions.size() == 0, "all paths should have been tried");
3479 return NULL;
3480 }
3481 }
3482 if (leading->is_Region()) {
3483 regions.push(leading, 2);
3484 leading = leading->in(1);
3485 } else {
3486 leading = leading->in(0);
3487 }
3488 }
3489 #ifdef ASSERT
3490 Unique_Node_List wq;
3491 wq.push((Node*)this);
3492 uint found = 0;
3493 for (uint i = 0; i < wq.size(); i++) {
3494 Node* n = wq.at(i);
3495 if (n->is_Region()) {
3496 for (uint j = 1; j < n->req(); j++) {
3497 Node* in = n->in(j);
3498 if (in != NULL && !in->is_top()) {
3499 wq.push(in);
3500 }
3501 }
3502 } else {
3503 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3504 assert(n == leading, "consistency check failed");
3505 found++;
3506 } else {
3507 Node* in = n->in(0);
3508 if (in != NULL && !in->is_top()) {
3509 wq.push(in);
3510 }
3511 }
3512 }
3513 }
3514 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3515 #endif
3516 if (leading == NULL) {
3517 return NULL;
3518 }
3519 MemBarNode* mb = leading->as_MemBar();
3520 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3521 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3522 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3523 return mb;
3524 }
3525
3526 //===========================InitializeNode====================================
3527 // SUMMARY:
3528 // This node acts as a memory barrier on raw memory, after some raw stores.
3529 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3530 // The Initialize can 'capture' suitably constrained stores as raw inits.
3531 // It can coalesce related raw stores into larger units (called 'tiles').
3532 // It can avoid zeroing new storage for memory units which have raw inits.
3533 // At macro-expansion, it is marked 'complete', and does not optimize further.
3534 //
3535 // EXAMPLE:
3536 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3537 // ctl = incoming control; mem* = incoming memory
3538 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3539 // First allocate uninitialized memory and fill in the header:
3540 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3541 // ctl := alloc.Control; mem* := alloc.Memory*
3542 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3543 // Then initialize to zero the non-header parts of the raw memory block:
3544 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3545 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3546 // After the initialize node executes, the object is ready for service:
3547 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3548 // Suppose its body is immediately initialized as {1,2}:
3549 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3550 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3551 // mem.SLICE(#short[*]) := store2
3552 //
3553 // DETAILS:
3554 // An InitializeNode collects and isolates object initialization after
3555 // an AllocateNode and before the next possible safepoint. As a
3556 // memory barrier (MemBarNode), it keeps critical stores from drifting
3557 // down past any safepoint or any publication of the allocation.
3558 // Before this barrier, a newly-allocated object may have uninitialized bits.
3559 // After this barrier, it may be treated as a real oop, and GC is allowed.
3560 //
3561 // The semantics of the InitializeNode include an implicit zeroing of
3562 // the new object from object header to the end of the object.
3563 // (The object header and end are determined by the AllocateNode.)
3564 //
3565 // Certain stores may be added as direct inputs to the InitializeNode.
3566 // These stores must update raw memory, and they must be to addresses
3567 // derived from the raw address produced by AllocateNode, and with
3568 // a constant offset. They must be ordered by increasing offset.
3569 // The first one is at in(RawStores), the last at in(req()-1).
3570 // Unlike most memory operations, they are not linked in a chain,
3571 // but are displayed in parallel as users of the rawmem output of
3572 // the allocation.
3573 //
3574 // (See comments in InitializeNode::capture_store, which continue
3575 // the example given above.)
3576 //
3577 // When the associated Allocate is macro-expanded, the InitializeNode
3578 // may be rewritten to optimize collected stores. A ClearArrayNode
3579 // may also be created at that point to represent any required zeroing.
3580 // The InitializeNode is then marked 'complete', prohibiting further
3581 // capturing of nearby memory operations.
3582 //
3583 // During macro-expansion, all captured initializations which store
3584 // constant values of 32 bits or smaller are coalesced (if advantageous)
3585 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3586 // initialized in fewer memory operations. Memory words which are
3587 // covered by neither tiles nor non-constant stores are pre-zeroed
3588 // by explicit stores of zero. (The code shape happens to do all
3589 // zeroing first, then all other stores, with both sequences occurring
3590 // in order of ascending offsets.)
3591 //
3592 // Alternatively, code may be inserted between an AllocateNode and its
3593 // InitializeNode, to perform arbitrary initialization of the new object.
3594 // E.g., the object copying intrinsics insert complex data transfers here.
3595 // The initialization must then be marked as 'complete' disable the
3596 // built-in zeroing semantics and the collection of initializing stores.
3597 //
3598 // While an InitializeNode is incomplete, reads from the memory state
3599 // produced by it are optimizable if they match the control edge and
3600 // new oop address associated with the allocation/initialization.
3601 // They return a stored value (if the offset matches) or else zero.
3602 // A write to the memory state, if it matches control and address,
3603 // and if it is to a constant offset, may be 'captured' by the
3604 // InitializeNode. It is cloned as a raw memory operation and rewired
3605 // inside the initialization, to the raw oop produced by the allocation.
3606 // Operations on addresses which are provably distinct (e.g., to
3607 // other AllocateNodes) are allowed to bypass the initialization.
3608 //
3609 // The effect of all this is to consolidate object initialization
3610 // (both arrays and non-arrays, both piecewise and bulk) into a
3611 // single location, where it can be optimized as a unit.
3612 //
3613 // Only stores with an offset less than TrackedInitializationLimit words
3614 // will be considered for capture by an InitializeNode. This puts a
3615 // reasonable limit on the complexity of optimized initializations.
3616
3617 //---------------------------InitializeNode------------------------------------
3618 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3619 : MemBarNode(C, adr_type, rawoop),
3620 _is_complete(Incomplete), _does_not_escape(false)
3621 {
3622 init_class_id(Class_Initialize);
3623
3624 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3625 assert(in(RawAddress) == rawoop, "proper init");
3626 // Note: allocation() can be NULL, for secondary initialization barriers
3627 }
3628
3629 // Since this node is not matched, it will be processed by the
3630 // register allocator. Declare that there are no constraints
3631 // on the allocation of the RawAddress edge.
3632 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3633 // This edge should be set to top, by the set_complete. But be conservative.
3634 if (idx == InitializeNode::RawAddress)
3635 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3636 return RegMask::Empty;
3637 }
3638
3639 Node* InitializeNode::memory(uint alias_idx) {
3640 Node* mem = in(Memory);
3641 if (mem->is_MergeMem()) {
3642 return mem->as_MergeMem()->memory_at(alias_idx);
3643 } else {
3644 // incoming raw memory is not split
3645 return mem;
3646 }
3647 }
3648
3649 bool InitializeNode::is_non_zero() {
3650 if (is_complete()) return false;
3651 remove_extra_zeroes();
3652 return (req() > RawStores);
3653 }
3654
3655 void InitializeNode::set_complete(PhaseGVN* phase) {
3656 assert(!is_complete(), "caller responsibility");
3657 _is_complete = Complete;
3658
3659 // After this node is complete, it contains a bunch of
3660 // raw-memory initializations. There is no need for
3661 // it to have anything to do with non-raw memory effects.
3662 // Therefore, tell all non-raw users to re-optimize themselves,
3663 // after skipping the memory effects of this initialization.
3664 PhaseIterGVN* igvn = phase->is_IterGVN();
3665 if (igvn) igvn->add_users_to_worklist(this);
3666 }
3667
3668 // convenience function
3669 // return false if the init contains any stores already
3670 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3671 InitializeNode* init = initialization();
3672 if (init == NULL || init->is_complete()) {
3673 return false;
3674 }
3675 init->remove_extra_zeroes();
3676 // for now, if this allocation has already collected any inits, bail:
3677 if (init->is_non_zero()) return false;
3678 init->set_complete(phase);
3679 return true;
3680 }
3681
3682 void InitializeNode::remove_extra_zeroes() {
3683 if (req() == RawStores) return;
3684 Node* zmem = zero_memory();
3685 uint fill = RawStores;
3686 for (uint i = fill; i < req(); i++) {
3687 Node* n = in(i);
3688 if (n->is_top() || n == zmem) continue; // skip
3689 if (fill < i) set_req(fill, n); // compact
3690 ++fill;
3691 }
3692 // delete any empty spaces created:
3693 while (fill < req()) {
3694 del_req(fill);
3695 }
3696 }
3697
3698 // Helper for remembering which stores go with which offsets.
3699 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3700 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3701 intptr_t offset = -1;
3702 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3703 phase, offset);
3704 if (base == NULL) return -1; // something is dead,
3705 if (offset < 0) return -1; // dead, dead
3706 return offset;
3707 }
3708
3709 // Helper for proving that an initialization expression is
3710 // "simple enough" to be folded into an object initialization.
3711 // Attempts to prove that a store's initial value 'n' can be captured
3712 // within the initialization without creating a vicious cycle, such as:
3713 // { Foo p = new Foo(); p.next = p; }
3714 // True for constants and parameters and small combinations thereof.
3715 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3716 ResourceMark rm;
3717 Unique_Node_List worklist;
3718 worklist.push(value);
3719
3720 uint complexity_limit = 20;
3721 for (uint j = 0; j < worklist.size(); j++) {
3722 if (j >= complexity_limit) {
3723 return false; // Bail out if processed too many nodes
3724 }
3725
3726 Node* n = worklist.at(j);
3727 if (n == NULL) continue; // (can this really happen?)
3728 if (n->is_Proj()) n = n->in(0);
3729 if (n == this) return false; // found a cycle
3730 if (n->is_Con()) continue;
3731 if (n->is_Start()) continue; // params, etc., are OK
3732 if (n->is_Root()) continue; // even better
3733
3734 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3735 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3736 continue;
3737 }
3738
3739 Node* ctl = n->in(0);
3740 if (ctl != NULL && !ctl->is_top()) {
3741 if (ctl->is_Proj()) ctl = ctl->in(0);
3742 if (ctl == this) return false;
3743
3744 // If we already know that the enclosing memory op is pinned right after
3745 // the init, then any control flow that the store has picked up
3746 // must have preceded the init, or else be equal to the init.
3747 // Even after loop optimizations (which might change control edges)
3748 // a store is never pinned *before* the availability of its inputs.
3749 if (!MemNode::all_controls_dominate(n, this))
3750 return false; // failed to prove a good control
3751 }
3752
3753 // Check data edges for possible dependencies on 'this'.
3754 for (uint i = 1; i < n->req(); i++) {
3755 Node* m = n->in(i);
3756 if (m == NULL || m == n || m->is_top()) continue;
3757
3758 // Only process data inputs once
3759 worklist.push(m);
3760 }
3761 }
3762
3763 return true;
3764 }
3765
3766 // Here are all the checks a Store must pass before it can be moved into
3767 // an initialization. Returns zero if a check fails.
3768 // On success, returns the (constant) offset to which the store applies,
3769 // within the initialized memory.
3770 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3771 const int FAIL = 0;
3772 if (st->req() != MemNode::ValueIn + 1)
3773 return FAIL; // an inscrutable StoreNode (card mark?)
3774 Node* ctl = st->in(MemNode::Control);
3775 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3776 return FAIL; // must be unconditional after the initialization
3777 Node* mem = st->in(MemNode::Memory);
3778 if (!(mem->is_Proj() && mem->in(0) == this))
3779 return FAIL; // must not be preceded by other stores
3780 Node* adr = st->in(MemNode::Address);
3781 intptr_t offset;
3782 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3783 if (alloc == NULL)
3784 return FAIL; // inscrutable address
3785 if (alloc != allocation())
3786 return FAIL; // wrong allocation! (store needs to float up)
3787 int size_in_bytes = st->memory_size();
3788 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3789 return FAIL; // mismatched access
3790 }
3791 Node* val = st->in(MemNode::ValueIn);
3792
3793 if (!detect_init_independence(val, phase))
3794 return FAIL; // stored value must be 'simple enough'
3795
3796 // The Store can be captured only if nothing after the allocation
3797 // and before the Store is using the memory location that the store
3798 // overwrites.
3799 bool failed = false;
3800 // If is_complete_with_arraycopy() is true the shape of the graph is
3801 // well defined and is safe so no need for extra checks.
3802 if (!is_complete_with_arraycopy()) {
3803 // We are going to look at each use of the memory state following
3804 // the allocation to make sure nothing reads the memory that the
3805 // Store writes.
3806 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3807 int alias_idx = phase->C->get_alias_index(t_adr);
3808 ResourceMark rm;
3809 Unique_Node_List mems;
3810 mems.push(mem);
3811 Node* unique_merge = NULL;
3812 for (uint next = 0; next < mems.size(); ++next) {
3813 Node *m = mems.at(next);
3814 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3815 Node *n = m->fast_out(j);
3816 if (n->outcnt() == 0) {
3817 continue;
3818 }
3819 if (n == st) {
3820 continue;
3821 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3822 // If the control of this use is different from the control
3823 // of the Store which is right after the InitializeNode then
3824 // this node cannot be between the InitializeNode and the
3825 // Store.
3826 continue;
3827 } else if (n->is_MergeMem()) {
3828 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3829 // We can hit a MergeMemNode (that will likely go away
3830 // later) that is a direct use of the memory state
3831 // following the InitializeNode on the same slice as the
3832 // store node that we'd like to capture. We need to check
3833 // the uses of the MergeMemNode.
3834 mems.push(n);
3835 }
3836 } else if (n->is_Mem()) {
3837 Node* other_adr = n->in(MemNode::Address);
3838 if (other_adr == adr) {
3839 failed = true;
3840 break;
3841 } else {
3842 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3843 if (other_t_adr != NULL) {
3844 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3845 if (other_alias_idx == alias_idx) {
3846 // A load from the same memory slice as the store right
3847 // after the InitializeNode. We check the control of the
3848 // object/array that is loaded from. If it's the same as
3849 // the store control then we cannot capture the store.
3850 assert(!n->is_Store(), "2 stores to same slice on same control?");
3851 Node* base = other_adr;
3852 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3853 base = base->in(AddPNode::Base);
3854 if (base != NULL) {
3855 base = base->uncast();
3856 if (base->is_Proj() && base->in(0) == alloc) {
3857 failed = true;
3858 break;
3859 }
3860 }
3861 }
3862 }
3863 }
3864 } else {
3865 failed = true;
3866 break;
3867 }
3868 }
3869 }
3870 }
3871 if (failed) {
3872 if (!can_reshape) {
3873 // We decided we couldn't capture the store during parsing. We
3874 // should try again during the next IGVN once the graph is
3875 // cleaner.
3876 phase->C->record_for_igvn(st);
3877 }
3878 return FAIL;
3879 }
3880
3881 return offset; // success
3882 }
3883
3884 // Find the captured store in(i) which corresponds to the range
3885 // [start..start+size) in the initialized object.
3886 // If there is one, return its index i. If there isn't, return the
3887 // negative of the index where it should be inserted.
3888 // Return 0 if the queried range overlaps an initialization boundary
3889 // or if dead code is encountered.
3890 // If size_in_bytes is zero, do not bother with overlap checks.
3891 int InitializeNode::captured_store_insertion_point(intptr_t start,
3892 int size_in_bytes,
3893 PhaseTransform* phase) {
3894 const int FAIL = 0, MAX_STORE = BytesPerLong;
3895
3896 if (is_complete())
3897 return FAIL; // arraycopy got here first; punt
3898
3899 assert(allocation() != NULL, "must be present");
3900
3901 // no negatives, no header fields:
3902 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3903
3904 // after a certain size, we bail out on tracking all the stores:
3905 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3906 if (start >= ti_limit) return FAIL;
3907
3908 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3909 if (i >= limit) return -(int)i; // not found; here is where to put it
3910
3911 Node* st = in(i);
3912 intptr_t st_off = get_store_offset(st, phase);
3913 if (st_off < 0) {
3914 if (st != zero_memory()) {
3915 return FAIL; // bail out if there is dead garbage
3916 }
3917 } else if (st_off > start) {
3918 // ...we are done, since stores are ordered
3919 if (st_off < start + size_in_bytes) {
3920 return FAIL; // the next store overlaps
3921 }
3922 return -(int)i; // not found; here is where to put it
3923 } else if (st_off < start) {
3924 if (size_in_bytes != 0 &&
3925 start < st_off + MAX_STORE &&
3926 start < st_off + st->as_Store()->memory_size()) {
3927 return FAIL; // the previous store overlaps
3928 }
3929 } else {
3930 if (size_in_bytes != 0 &&
3931 st->as_Store()->memory_size() != size_in_bytes) {
3932 return FAIL; // mismatched store size
3933 }
3934 return i;
3935 }
3936
3937 ++i;
3938 }
3939 }
3940
3941 // Look for a captured store which initializes at the offset 'start'
3942 // with the given size. If there is no such store, and no other
3943 // initialization interferes, then return zero_memory (the memory
3944 // projection of the AllocateNode).
3945 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3946 PhaseTransform* phase) {
3947 assert(stores_are_sane(phase), "");
3948 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3949 if (i == 0) {
3950 return NULL; // something is dead
3951 } else if (i < 0) {
3952 return zero_memory(); // just primordial zero bits here
3953 } else {
3954 Node* st = in(i); // here is the store at this position
3955 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3956 return st;
3957 }
3958 }
3959
3960 // Create, as a raw pointer, an address within my new object at 'offset'.
3961 Node* InitializeNode::make_raw_address(intptr_t offset,
3962 PhaseTransform* phase) {
3963 Node* addr = in(RawAddress);
3964 if (offset != 0) {
3965 Compile* C = phase->C;
3966 addr = phase->transform( new AddPNode(C->top(), addr,
3967 phase->MakeConX(offset)) );
3968 }
3969 return addr;
3970 }
3971
3972 // Clone the given store, converting it into a raw store
3973 // initializing a field or element of my new object.
3974 // Caller is responsible for retiring the original store,
3975 // with subsume_node or the like.
3976 //
3977 // From the example above InitializeNode::InitializeNode,
3978 // here are the old stores to be captured:
3979 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3980 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3981 //
3982 // Here is the changed code; note the extra edges on init:
3983 // alloc = (Allocate ...)
3984 // rawoop = alloc.RawAddress
3985 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3986 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3987 // init = (Initialize alloc.Control alloc.Memory rawoop
3988 // rawstore1 rawstore2)
3989 //
3990 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3991 PhaseGVN* phase, bool can_reshape) {
3992 assert(stores_are_sane(phase), "");
3993
3994 if (start < 0) return NULL;
3995 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3996
3997 Compile* C = phase->C;
3998 int size_in_bytes = st->memory_size();
3999 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4000 if (i == 0) return NULL; // bail out
4001 Node* prev_mem = NULL; // raw memory for the captured store
4002 if (i > 0) {
4003 prev_mem = in(i); // there is a pre-existing store under this one
4004 set_req(i, C->top()); // temporarily disconnect it
4005 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4006 } else {
4007 i = -i; // no pre-existing store
4008 prev_mem = zero_memory(); // a slice of the newly allocated object
4009 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4010 set_req(--i, C->top()); // reuse this edge; it has been folded away
4011 else
4012 ins_req(i, C->top()); // build a new edge
4013 }
4014 Node* new_st = st->clone();
4015 new_st->set_req(MemNode::Control, in(Control));
4016 new_st->set_req(MemNode::Memory, prev_mem);
4017 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4018 new_st = phase->transform(new_st);
4019
4020 // At this point, new_st might have swallowed a pre-existing store
4021 // at the same offset, or perhaps new_st might have disappeared,
4022 // if it redundantly stored the same value (or zero to fresh memory).
4023
4024 // In any case, wire it in:
4025 phase->igvn_rehash_node_delayed(this);
4026 set_req(i, new_st);
4027
4028 // The caller may now kill the old guy.
4029 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4030 assert(check_st == new_st || check_st == NULL, "must be findable");
4031 assert(!is_complete(), "");
4032 return new_st;
4033 }
4034
4035 static bool store_constant(jlong* tiles, int num_tiles,
4036 intptr_t st_off, int st_size,
4037 jlong con) {
4038 if ((st_off & (st_size-1)) != 0)
4039 return false; // strange store offset (assume size==2**N)
4040 address addr = (address)tiles + st_off;
4041 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4042 switch (st_size) {
4043 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4044 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4045 case sizeof(jint): *(jint*) addr = (jint) con; break;
4046 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4047 default: return false; // strange store size (detect size!=2**N here)
4048 }
4049 return true; // return success to caller
4050 }
4051
4052 // Coalesce subword constants into int constants and possibly
4053 // into long constants. The goal, if the CPU permits,
4054 // is to initialize the object with a small number of 64-bit tiles.
4055 // Also, convert floating-point constants to bit patterns.
4056 // Non-constants are not relevant to this pass.
4057 //
4058 // In terms of the running example on InitializeNode::InitializeNode
4059 // and InitializeNode::capture_store, here is the transformation
4060 // of rawstore1 and rawstore2 into rawstore12:
4061 // alloc = (Allocate ...)
4062 // rawoop = alloc.RawAddress
4063 // tile12 = 0x00010002
4064 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4065 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4066 //
4067 void
4068 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4069 Node* size_in_bytes,
4070 PhaseGVN* phase) {
4071 Compile* C = phase->C;
4072
4073 assert(stores_are_sane(phase), "");
4074 // Note: After this pass, they are not completely sane,
4075 // since there may be some overlaps.
4076
4077 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4078
4079 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4080 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4081 size_limit = MIN2(size_limit, ti_limit);
4082 size_limit = align_up(size_limit, BytesPerLong);
4083 int num_tiles = size_limit / BytesPerLong;
4084
4085 // allocate space for the tile map:
4086 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4087 jlong tiles_buf[small_len];
4088 Node* nodes_buf[small_len];
4089 jlong inits_buf[small_len];
4090 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4091 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4092 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4093 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4094 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4095 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4096 // tiles: exact bitwise model of all primitive constants
4097 // nodes: last constant-storing node subsumed into the tiles model
4098 // inits: which bytes (in each tile) are touched by any initializations
4099
4100 //// Pass A: Fill in the tile model with any relevant stores.
4101
4102 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4103 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4104 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4105 Node* zmem = zero_memory(); // initially zero memory state
4106 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4107 Node* st = in(i);
4108 intptr_t st_off = get_store_offset(st, phase);
4109
4110 // Figure out the store's offset and constant value:
4111 if (st_off < header_size) continue; //skip (ignore header)
4112 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4113 int st_size = st->as_Store()->memory_size();
4114 if (st_off + st_size > size_limit) break;
4115
4116 // Record which bytes are touched, whether by constant or not.
4117 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4118 continue; // skip (strange store size)
4119
4120 const Type* val = phase->type(st->in(MemNode::ValueIn));
4121 if (!val->singleton()) continue; //skip (non-con store)
4122 BasicType type = val->basic_type();
4123
4124 jlong con = 0;
4125 switch (type) {
4126 case T_INT: con = val->is_int()->get_con(); break;
4127 case T_LONG: con = val->is_long()->get_con(); break;
4128 case T_FLOAT: con = jint_cast(val->getf()); break;
4129 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4130 default: continue; //skip (odd store type)
4131 }
4132
4133 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4134 st->Opcode() == Op_StoreL) {
4135 continue; // This StoreL is already optimal.
4136 }
4137
4138 // Store down the constant.
4139 store_constant(tiles, num_tiles, st_off, st_size, con);
4140
4141 intptr_t j = st_off >> LogBytesPerLong;
4142
4143 if (type == T_INT && st_size == BytesPerInt
4144 && (st_off & BytesPerInt) == BytesPerInt) {
4145 jlong lcon = tiles[j];
4146 if (!Matcher::isSimpleConstant64(lcon) &&
4147 st->Opcode() == Op_StoreI) {
4148 // This StoreI is already optimal by itself.
4149 jint* intcon = (jint*) &tiles[j];
4150 intcon[1] = 0; // undo the store_constant()
4151
4152 // If the previous store is also optimal by itself, back up and
4153 // undo the action of the previous loop iteration... if we can.
4154 // But if we can't, just let the previous half take care of itself.
4155 st = nodes[j];
4156 st_off -= BytesPerInt;
4157 con = intcon[0];
4158 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4159 assert(st_off >= header_size, "still ignoring header");
4160 assert(get_store_offset(st, phase) == st_off, "must be");
4161 assert(in(i-1) == zmem, "must be");
4162 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4163 assert(con == tcon->is_int()->get_con(), "must be");
4164 // Undo the effects of the previous loop trip, which swallowed st:
4165 intcon[0] = 0; // undo store_constant()
4166 set_req(i-1, st); // undo set_req(i, zmem)
4167 nodes[j] = NULL; // undo nodes[j] = st
4168 --old_subword; // undo ++old_subword
4169 }
4170 continue; // This StoreI is already optimal.
4171 }
4172 }
4173
4174 // This store is not needed.
4175 set_req(i, zmem);
4176 nodes[j] = st; // record for the moment
4177 if (st_size < BytesPerLong) // something has changed
4178 ++old_subword; // includes int/float, but who's counting...
4179 else ++old_long;
4180 }
4181
4182 if ((old_subword + old_long) == 0)
4183 return; // nothing more to do
4184
4185 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4186 // Be sure to insert them before overlapping non-constant stores.
4187 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4188 for (int j = 0; j < num_tiles; j++) {
4189 jlong con = tiles[j];
4190 jlong init = inits[j];
4191 if (con == 0) continue;
4192 jint con0, con1; // split the constant, address-wise
4193 jint init0, init1; // split the init map, address-wise
4194 { union { jlong con; jint intcon[2]; } u;
4195 u.con = con;
4196 con0 = u.intcon[0];
4197 con1 = u.intcon[1];
4198 u.con = init;
4199 init0 = u.intcon[0];
4200 init1 = u.intcon[1];
4201 }
4202
4203 Node* old = nodes[j];
4204 assert(old != NULL, "need the prior store");
4205 intptr_t offset = (j * BytesPerLong);
4206
4207 bool split = !Matcher::isSimpleConstant64(con);
4208
4209 if (offset < header_size) {
4210 assert(offset + BytesPerInt >= header_size, "second int counts");
4211 assert(*(jint*)&tiles[j] == 0, "junk in header");
4212 split = true; // only the second word counts
4213 // Example: int a[] = { 42 ... }
4214 } else if (con0 == 0 && init0 == -1) {
4215 split = true; // first word is covered by full inits
4216 // Example: int a[] = { ... foo(), 42 ... }
4217 } else if (con1 == 0 && init1 == -1) {
4218 split = true; // second word is covered by full inits
4219 // Example: int a[] = { ... 42, foo() ... }
4220 }
4221
4222 // Here's a case where init0 is neither 0 nor -1:
4223 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4224 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4225 // In this case the tile is not split; it is (jlong)42.
4226 // The big tile is stored down, and then the foo() value is inserted.
4227 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4228
4229 Node* ctl = old->in(MemNode::Control);
4230 Node* adr = make_raw_address(offset, phase);
4231 const TypePtr* atp = TypeRawPtr::BOTTOM;
4232
4233 // One or two coalesced stores to plop down.
4234 Node* st[2];
4235 intptr_t off[2];
4236 int nst = 0;
4237 if (!split) {
4238 ++new_long;
4239 off[nst] = offset;
4240 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4241 phase->longcon(con), T_LONG, MemNode::unordered);
4242 } else {
4243 // Omit either if it is a zero.
4244 if (con0 != 0) {
4245 ++new_int;
4246 off[nst] = offset;
4247 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4248 phase->intcon(con0), T_INT, MemNode::unordered);
4249 }
4250 if (con1 != 0) {
4251 ++new_int;
4252 offset += BytesPerInt;
4253 adr = make_raw_address(offset, phase);
4254 off[nst] = offset;
4255 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4256 phase->intcon(con1), T_INT, MemNode::unordered);
4257 }
4258 }
4259
4260 // Insert second store first, then the first before the second.
4261 // Insert each one just before any overlapping non-constant stores.
4262 while (nst > 0) {
4263 Node* st1 = st[--nst];
4264 C->copy_node_notes_to(st1, old);
4265 st1 = phase->transform(st1);
4266 offset = off[nst];
4267 assert(offset >= header_size, "do not smash header");
4268 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4269 guarantee(ins_idx != 0, "must re-insert constant store");
4270 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4271 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4272 set_req(--ins_idx, st1);
4273 else
4274 ins_req(ins_idx, st1);
4275 }
4276 }
4277
4278 if (PrintCompilation && WizardMode)
4279 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4280 old_subword, old_long, new_int, new_long);
4281 if (C->log() != NULL)
4282 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4283 old_subword, old_long, new_int, new_long);
4284
4285 // Clean up any remaining occurrences of zmem:
4286 remove_extra_zeroes();
4287 }
4288
4289 // Explore forward from in(start) to find the first fully initialized
4290 // word, and return its offset. Skip groups of subword stores which
4291 // together initialize full words. If in(start) is itself part of a
4292 // fully initialized word, return the offset of in(start). If there
4293 // are no following full-word stores, or if something is fishy, return
4294 // a negative value.
4295 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4296 int int_map = 0;
4297 intptr_t int_map_off = 0;
4298 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4299
4300 for (uint i = start, limit = req(); i < limit; i++) {
4301 Node* st = in(i);
4302
4303 intptr_t st_off = get_store_offset(st, phase);
4304 if (st_off < 0) break; // return conservative answer
4305
4306 int st_size = st->as_Store()->memory_size();
4307 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4308 return st_off; // we found a complete word init
4309 }
4310
4311 // update the map:
4312
4313 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4314 if (this_int_off != int_map_off) {
4315 // reset the map:
4316 int_map = 0;
4317 int_map_off = this_int_off;
4318 }
4319
4320 int subword_off = st_off - this_int_off;
4321 int_map |= right_n_bits(st_size) << subword_off;
4322 if ((int_map & FULL_MAP) == FULL_MAP) {
4323 return this_int_off; // we found a complete word init
4324 }
4325
4326 // Did this store hit or cross the word boundary?
4327 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4328 if (next_int_off == this_int_off + BytesPerInt) {
4329 // We passed the current int, without fully initializing it.
4330 int_map_off = next_int_off;
4331 int_map >>= BytesPerInt;
4332 } else if (next_int_off > this_int_off + BytesPerInt) {
4333 // We passed the current and next int.
4334 return this_int_off + BytesPerInt;
4335 }
4336 }
4337
4338 return -1;
4339 }
4340
4341
4342 // Called when the associated AllocateNode is expanded into CFG.
4343 // At this point, we may perform additional optimizations.
4344 // Linearize the stores by ascending offset, to make memory
4345 // activity as coherent as possible.
4346 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4347 intptr_t header_size,
4348 Node* size_in_bytes,
4349 PhaseGVN* phase) {
4350 assert(!is_complete(), "not already complete");
4351 assert(stores_are_sane(phase), "");
4352 assert(allocation() != NULL, "must be present");
4353
4354 remove_extra_zeroes();
4355
4356 if (ReduceFieldZeroing || ReduceBulkZeroing)
4357 // reduce instruction count for common initialization patterns
4358 coalesce_subword_stores(header_size, size_in_bytes, phase);
4359
4360 Node* zmem = zero_memory(); // initially zero memory state
4361 Node* inits = zmem; // accumulating a linearized chain of inits
4362 #ifdef ASSERT
4363 intptr_t first_offset = allocation()->minimum_header_size();
4364 intptr_t last_init_off = first_offset; // previous init offset
4365 intptr_t last_init_end = first_offset; // previous init offset+size
4366 intptr_t last_tile_end = first_offset; // previous tile offset+size
4367 #endif
4368 intptr_t zeroes_done = header_size;
4369
4370 bool do_zeroing = true; // we might give up if inits are very sparse
4371 int big_init_gaps = 0; // how many large gaps have we seen?
4372
4373 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4374 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4375
4376 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4377 Node* st = in(i);
4378 intptr_t st_off = get_store_offset(st, phase);
4379 if (st_off < 0)
4380 break; // unknown junk in the inits
4381 if (st->in(MemNode::Memory) != zmem)
4382 break; // complicated store chains somehow in list
4383
4384 int st_size = st->as_Store()->memory_size();
4385 intptr_t next_init_off = st_off + st_size;
4386
4387 if (do_zeroing && zeroes_done < next_init_off) {
4388 // See if this store needs a zero before it or under it.
4389 intptr_t zeroes_needed = st_off;
4390
4391 if (st_size < BytesPerInt) {
4392 // Look for subword stores which only partially initialize words.
4393 // If we find some, we must lay down some word-level zeroes first,
4394 // underneath the subword stores.
4395 //
4396 // Examples:
4397 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4398 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4399 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4400 //
4401 // Note: coalesce_subword_stores may have already done this,
4402 // if it was prompted by constant non-zero subword initializers.
4403 // But this case can still arise with non-constant stores.
4404
4405 intptr_t next_full_store = find_next_fullword_store(i, phase);
4406
4407 // In the examples above:
4408 // in(i) p q r s x y z
4409 // st_off 12 13 14 15 12 13 14
4410 // st_size 1 1 1 1 1 1 1
4411 // next_full_s. 12 16 16 16 16 16 16
4412 // z's_done 12 16 16 16 12 16 12
4413 // z's_needed 12 16 16 16 16 16 16
4414 // zsize 0 0 0 0 4 0 4
4415 if (next_full_store < 0) {
4416 // Conservative tack: Zero to end of current word.
4417 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4418 } else {
4419 // Zero to beginning of next fully initialized word.
4420 // Or, don't zero at all, if we are already in that word.
4421 assert(next_full_store >= zeroes_needed, "must go forward");
4422 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4423 zeroes_needed = next_full_store;
4424 }
4425 }
4426
4427 if (zeroes_needed > zeroes_done) {
4428 intptr_t zsize = zeroes_needed - zeroes_done;
4429 // Do some incremental zeroing on rawmem, in parallel with inits.
4430 zeroes_done = align_down(zeroes_done, BytesPerInt);
4431 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4432 allocation()->in(AllocateNode::DefaultValue),
4433 allocation()->in(AllocateNode::RawDefaultValue),
4434 zeroes_done, zeroes_needed,
4435 phase);
4436 zeroes_done = zeroes_needed;
4437 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4438 do_zeroing = false; // leave the hole, next time
4439 }
4440 }
4441
4442 // Collect the store and move on:
4443 st->set_req(MemNode::Memory, inits);
4444 inits = st; // put it on the linearized chain
4445 set_req(i, zmem); // unhook from previous position
4446
4447 if (zeroes_done == st_off)
4448 zeroes_done = next_init_off;
4449
4450 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4451
4452 #ifdef ASSERT
4453 // Various order invariants. Weaker than stores_are_sane because
4454 // a large constant tile can be filled in by smaller non-constant stores.
4455 assert(st_off >= last_init_off, "inits do not reverse");
4456 last_init_off = st_off;
4457 const Type* val = NULL;
4458 if (st_size >= BytesPerInt &&
4459 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4460 (int)val->basic_type() < (int)T_OBJECT) {
4461 assert(st_off >= last_tile_end, "tiles do not overlap");
4462 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4463 last_tile_end = MAX2(last_tile_end, next_init_off);
4464 } else {
4465 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4466 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4467 assert(st_off >= last_init_end, "inits do not overlap");
4468 last_init_end = next_init_off; // it's a non-tile
4469 }
4470 #endif //ASSERT
4471 }
4472
4473 remove_extra_zeroes(); // clear out all the zmems left over
4474 add_req(inits);
4475
4476 if (!(UseTLAB && ZeroTLAB)) {
4477 // If anything remains to be zeroed, zero it all now.
4478 zeroes_done = align_down(zeroes_done, BytesPerInt);
4479 // if it is the last unused 4 bytes of an instance, forget about it
4480 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4481 if (zeroes_done + BytesPerLong >= size_limit) {
4482 AllocateNode* alloc = allocation();
4483 assert(alloc != NULL, "must be present");
4484 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4485 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4486 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4487 if (zeroes_done == k->layout_helper())
4488 zeroes_done = size_limit;
4489 }
4490 }
4491 if (zeroes_done < size_limit) {
4492 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4493 allocation()->in(AllocateNode::DefaultValue),
4494 allocation()->in(AllocateNode::RawDefaultValue),
4495 zeroes_done, size_in_bytes, phase);
4496 }
4497 }
4498
4499 set_complete(phase);
4500 return rawmem;
4501 }
4502
4503
4504 #ifdef ASSERT
4505 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4506 if (is_complete())
4507 return true; // stores could be anything at this point
4508 assert(allocation() != NULL, "must be present");
4509 intptr_t last_off = allocation()->minimum_header_size();
4510 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4511 Node* st = in(i);
4512 intptr_t st_off = get_store_offset(st, phase);
4513 if (st_off < 0) continue; // ignore dead garbage
4514 if (last_off > st_off) {
4515 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4516 this->dump(2);
4517 assert(false, "ascending store offsets");
4518 return false;
4519 }
4520 last_off = st_off + st->as_Store()->memory_size();
4521 }
4522 return true;
4523 }
4524 #endif //ASSERT
4525
4526
4527
4528
4529 //============================MergeMemNode=====================================
4530 //
4531 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4532 // contributing store or call operations. Each contributor provides the memory
4533 // state for a particular "alias type" (see Compile::alias_type). For example,
4534 // if a MergeMem has an input X for alias category #6, then any memory reference
4535 // to alias category #6 may use X as its memory state input, as an exact equivalent
4536 // to using the MergeMem as a whole.
4537 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4538 //
4539 // (Here, the <N> notation gives the index of the relevant adr_type.)
4540 //
4541 // In one special case (and more cases in the future), alias categories overlap.
4542 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4543 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4544 // it is exactly equivalent to that state W:
4545 // MergeMem(<Bot>: W) <==> W
4546 //
4547 // Usually, the merge has more than one input. In that case, where inputs
4548 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4549 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4550 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4551 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4552 //
4553 // A merge can take a "wide" memory state as one of its narrow inputs.
4554 // This simply means that the merge observes out only the relevant parts of
4555 // the wide input. That is, wide memory states arriving at narrow merge inputs
4556 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4557 //
4558 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4559 // and that memory slices "leak through":
4560 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4561 //
4562 // But, in such a cascade, repeated memory slices can "block the leak":
4563 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4564 //
4565 // In the last example, Y is not part of the combined memory state of the
4566 // outermost MergeMem. The system must, of course, prevent unschedulable
4567 // memory states from arising, so you can be sure that the state Y is somehow
4568 // a precursor to state Y'.
4569 //
4570 //
4571 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4572 // of each MergeMemNode array are exactly the numerical alias indexes, including
4573 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4574 // Compile::alias_type (and kin) produce and manage these indexes.
4575 //
4576 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4577 // (Note that this provides quick access to the top node inside MergeMem methods,
4578 // without the need to reach out via TLS to Compile::current.)
4579 //
4580 // As a consequence of what was just described, a MergeMem that represents a full
4581 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4582 // containing all alias categories.
4583 //
4584 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4585 //
4586 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4587 // a memory state for the alias type <N>, or else the top node, meaning that
4588 // there is no particular input for that alias type. Note that the length of
4589 // a MergeMem is variable, and may be extended at any time to accommodate new
4590 // memory states at larger alias indexes. When merges grow, they are of course
4591 // filled with "top" in the unused in() positions.
4592 //
4593 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4594 // (Top was chosen because it works smoothly with passes like GCM.)
4595 //
4596 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4597 // the type of random VM bits like TLS references.) Since it is always the
4598 // first non-Bot memory slice, some low-level loops use it to initialize an
4599 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4600 //
4601 //
4602 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4603 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4604 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4605 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4606 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4607 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4608 //
4609 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4610 // really that different from the other memory inputs. An abbreviation called
4611 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4612 //
4613 //
4614 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4615 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4616 // that "emerges though" the base memory will be marked as excluding the alias types
4617 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4618 //
4619 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4620 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4621 //
4622 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4623 // (It is currently unimplemented.) As you can see, the resulting merge is
4624 // actually a disjoint union of memory states, rather than an overlay.
4625 //
4626
4627 //------------------------------MergeMemNode-----------------------------------
4628 Node* MergeMemNode::make_empty_memory() {
4629 Node* empty_memory = (Node*) Compile::current()->top();
4630 assert(empty_memory->is_top(), "correct sentinel identity");
4631 return empty_memory;
4632 }
4633
4634 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4635 init_class_id(Class_MergeMem);
4636 // all inputs are nullified in Node::Node(int)
4637 // set_input(0, NULL); // no control input
4638
4639 // Initialize the edges uniformly to top, for starters.
4640 Node* empty_mem = make_empty_memory();
4641 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4642 init_req(i,empty_mem);
4643 }
4644 assert(empty_memory() == empty_mem, "");
4645
4646 if( new_base != NULL && new_base->is_MergeMem() ) {
4647 MergeMemNode* mdef = new_base->as_MergeMem();
4648 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4649 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4650 mms.set_memory(mms.memory2());
4651 }
4652 assert(base_memory() == mdef->base_memory(), "");
4653 } else {
4654 set_base_memory(new_base);
4655 }
4656 }
4657
4658 // Make a new, untransformed MergeMem with the same base as 'mem'.
4659 // If mem is itself a MergeMem, populate the result with the same edges.
4660 MergeMemNode* MergeMemNode::make(Node* mem) {
4661 return new MergeMemNode(mem);
4662 }
4663
4664 //------------------------------cmp--------------------------------------------
4665 uint MergeMemNode::hash() const { return NO_HASH; }
4666 bool MergeMemNode::cmp( const Node &n ) const {
4667 return (&n == this); // Always fail except on self
4668 }
4669
4670 //------------------------------Identity---------------------------------------
4671 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4672 // Identity if this merge point does not record any interesting memory
4673 // disambiguations.
4674 Node* base_mem = base_memory();
4675 Node* empty_mem = empty_memory();
4676 if (base_mem != empty_mem) { // Memory path is not dead?
4677 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4678 Node* mem = in(i);
4679 if (mem != empty_mem && mem != base_mem) {
4680 return this; // Many memory splits; no change
4681 }
4682 }
4683 }
4684 return base_mem; // No memory splits; ID on the one true input
4685 }
4686
4687 //------------------------------Ideal------------------------------------------
4688 // This method is invoked recursively on chains of MergeMem nodes
4689 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4690 // Remove chain'd MergeMems
4691 //
4692 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4693 // relative to the "in(Bot)". Since we are patching both at the same time,
4694 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4695 // but rewrite each "in(i)" relative to the new "in(Bot)".
4696 Node *progress = NULL;
4697
4698
4699 Node* old_base = base_memory();
4700 Node* empty_mem = empty_memory();
4701 if (old_base == empty_mem)
4702 return NULL; // Dead memory path.
4703
4704 MergeMemNode* old_mbase;
4705 if (old_base != NULL && old_base->is_MergeMem())
4706 old_mbase = old_base->as_MergeMem();
4707 else
4708 old_mbase = NULL;
4709 Node* new_base = old_base;
4710
4711 // simplify stacked MergeMems in base memory
4712 if (old_mbase) new_base = old_mbase->base_memory();
4713
4714 // the base memory might contribute new slices beyond my req()
4715 if (old_mbase) grow_to_match(old_mbase);
4716
4717 // Look carefully at the base node if it is a phi.
4718 PhiNode* phi_base;
4719 if (new_base != NULL && new_base->is_Phi())
4720 phi_base = new_base->as_Phi();
4721 else
4722 phi_base = NULL;
4723
4724 Node* phi_reg = NULL;
4725 uint phi_len = (uint)-1;
4726 if (phi_base != NULL && !phi_base->is_copy()) {
4727 // do not examine phi if degraded to a copy
4728 phi_reg = phi_base->region();
4729 phi_len = phi_base->req();
4730 // see if the phi is unfinished
4731 for (uint i = 1; i < phi_len; i++) {
4732 if (phi_base->in(i) == NULL) {
4733 // incomplete phi; do not look at it yet!
4734 phi_reg = NULL;
4735 phi_len = (uint)-1;
4736 break;
4737 }
4738 }
4739 }
4740
4741 // Note: We do not call verify_sparse on entry, because inputs
4742 // can normalize to the base_memory via subsume_node or similar
4743 // mechanisms. This method repairs that damage.
4744
4745 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4746
4747 // Look at each slice.
4748 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4749 Node* old_in = in(i);
4750 // calculate the old memory value
4751 Node* old_mem = old_in;
4752 if (old_mem == empty_mem) old_mem = old_base;
4753 assert(old_mem == memory_at(i), "");
4754
4755 // maybe update (reslice) the old memory value
4756
4757 // simplify stacked MergeMems
4758 Node* new_mem = old_mem;
4759 MergeMemNode* old_mmem;
4760 if (old_mem != NULL && old_mem->is_MergeMem())
4761 old_mmem = old_mem->as_MergeMem();
4762 else
4763 old_mmem = NULL;
4764 if (old_mmem == this) {
4765 // This can happen if loops break up and safepoints disappear.
4766 // A merge of BotPtr (default) with a RawPtr memory derived from a
4767 // safepoint can be rewritten to a merge of the same BotPtr with
4768 // the BotPtr phi coming into the loop. If that phi disappears
4769 // also, we can end up with a self-loop of the mergemem.
4770 // In general, if loops degenerate and memory effects disappear,
4771 // a mergemem can be left looking at itself. This simply means
4772 // that the mergemem's default should be used, since there is
4773 // no longer any apparent effect on this slice.
4774 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4775 // from start. Update the input to TOP.
4776 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4777 }
4778 else if (old_mmem != NULL) {
4779 new_mem = old_mmem->memory_at(i);
4780 }
4781 // else preceding memory was not a MergeMem
4782
4783 // replace equivalent phis (unfortunately, they do not GVN together)
4784 if (new_mem != NULL && new_mem != new_base &&
4785 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4786 if (new_mem->is_Phi()) {
4787 PhiNode* phi_mem = new_mem->as_Phi();
4788 for (uint i = 1; i < phi_len; i++) {
4789 if (phi_base->in(i) != phi_mem->in(i)) {
4790 phi_mem = NULL;
4791 break;
4792 }
4793 }
4794 if (phi_mem != NULL) {
4795 // equivalent phi nodes; revert to the def
4796 new_mem = new_base;
4797 }
4798 }
4799 }
4800
4801 // maybe store down a new value
4802 Node* new_in = new_mem;
4803 if (new_in == new_base) new_in = empty_mem;
4804
4805 if (new_in != old_in) {
4806 // Warning: Do not combine this "if" with the previous "if"
4807 // A memory slice might have be be rewritten even if it is semantically
4808 // unchanged, if the base_memory value has changed.
4809 set_req(i, new_in);
4810 progress = this; // Report progress
4811 }
4812 }
4813
4814 if (new_base != old_base) {
4815 set_req(Compile::AliasIdxBot, new_base);
4816 // Don't use set_base_memory(new_base), because we need to update du.
4817 assert(base_memory() == new_base, "");
4818 progress = this;
4819 }
4820
4821 if( base_memory() == this ) {
4822 // a self cycle indicates this memory path is dead
4823 set_req(Compile::AliasIdxBot, empty_mem);
4824 }
4825
4826 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4827 // Recursion must occur after the self cycle check above
4828 if( base_memory()->is_MergeMem() ) {
4829 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4830 Node *m = phase->transform(new_mbase); // Rollup any cycles
4831 if( m != NULL &&
4832 (m->is_top() ||
4833 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4834 // propagate rollup of dead cycle to self
4835 set_req(Compile::AliasIdxBot, empty_mem);
4836 }
4837 }
4838
4839 if( base_memory() == empty_mem ) {
4840 progress = this;
4841 // Cut inputs during Parse phase only.
4842 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4843 if( !can_reshape ) {
4844 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4845 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4846 }
4847 }
4848 }
4849
4850 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4851 // Check if PhiNode::Ideal's "Split phis through memory merges"
4852 // transform should be attempted. Look for this->phi->this cycle.
4853 uint merge_width = req();
4854 if (merge_width > Compile::AliasIdxRaw) {
4855 PhiNode* phi = base_memory()->as_Phi();
4856 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4857 if (phi->in(i) == this) {
4858 phase->is_IterGVN()->_worklist.push(phi);
4859 break;
4860 }
4861 }
4862 }
4863 }
4864
4865 assert(progress || verify_sparse(), "please, no dups of base");
4866 return progress;
4867 }
4868
4869 //-------------------------set_base_memory-------------------------------------
4870 void MergeMemNode::set_base_memory(Node *new_base) {
4871 Node* empty_mem = empty_memory();
4872 set_req(Compile::AliasIdxBot, new_base);
4873 assert(memory_at(req()) == new_base, "must set default memory");
4874 // Clear out other occurrences of new_base:
4875 if (new_base != empty_mem) {
4876 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4877 if (in(i) == new_base) set_req(i, empty_mem);
4878 }
4879 }
4880 }
4881
4882 //------------------------------out_RegMask------------------------------------
4883 const RegMask &MergeMemNode::out_RegMask() const {
4884 return RegMask::Empty;
4885 }
4886
4887 //------------------------------dump_spec--------------------------------------
4888 #ifndef PRODUCT
4889 void MergeMemNode::dump_spec(outputStream *st) const {
4890 st->print(" {");
4891 Node* base_mem = base_memory();
4892 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4893 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4894 if (mem == base_mem) { st->print(" -"); continue; }
4895 st->print( " N%d:", mem->_idx );
4896 Compile::current()->get_adr_type(i)->dump_on(st);
4897 }
4898 st->print(" }");
4899 }
4900 #endif // !PRODUCT
4901
4902
4903 #ifdef ASSERT
4904 static bool might_be_same(Node* a, Node* b) {
4905 if (a == b) return true;
4906 if (!(a->is_Phi() || b->is_Phi())) return false;
4907 // phis shift around during optimization
4908 return true; // pretty stupid...
4909 }
4910
4911 // verify a narrow slice (either incoming or outgoing)
4912 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4913 if (!VerifyAliases) return; // don't bother to verify unless requested
4914 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4915 if (Node::in_dump()) return; // muzzle asserts when printing
4916 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4917 assert(n != NULL, "");
4918 // Elide intervening MergeMem's
4919 while (n->is_MergeMem()) {
4920 n = n->as_MergeMem()->memory_at(alias_idx);
4921 }
4922 Compile* C = Compile::current();
4923 const TypePtr* n_adr_type = n->adr_type();
4924 if (n == m->empty_memory()) {
4925 // Implicit copy of base_memory()
4926 } else if (n_adr_type != TypePtr::BOTTOM) {
4927 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4928 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4929 } else {
4930 // A few places like make_runtime_call "know" that VM calls are narrow,
4931 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4932 bool expected_wide_mem = false;
4933 if (n == m->base_memory()) {
4934 expected_wide_mem = true;
4935 } else if (alias_idx == Compile::AliasIdxRaw ||
4936 n == m->memory_at(Compile::AliasIdxRaw)) {
4937 expected_wide_mem = true;
4938 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4939 // memory can "leak through" calls on channels that
4940 // are write-once. Allow this also.
4941 expected_wide_mem = true;
4942 }
4943 assert(expected_wide_mem, "expected narrow slice replacement");
4944 }
4945 }
4946 #else // !ASSERT
4947 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4948 #endif
4949
4950
4951 //-----------------------------memory_at---------------------------------------
4952 Node* MergeMemNode::memory_at(uint alias_idx) const {
4953 assert(alias_idx >= Compile::AliasIdxRaw ||
4954 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4955 "must avoid base_memory and AliasIdxTop");
4956
4957 // Otherwise, it is a narrow slice.
4958 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4959 Compile *C = Compile::current();
4960 if (is_empty_memory(n)) {
4961 // the array is sparse; empty slots are the "top" node
4962 n = base_memory();
4963 assert(Node::in_dump()
4964 || n == NULL || n->bottom_type() == Type::TOP
4965 || n->adr_type() == NULL // address is TOP
4966 || n->adr_type() == TypePtr::BOTTOM
4967 || n->adr_type() == TypeRawPtr::BOTTOM
4968 || Compile::current()->AliasLevel() == 0,
4969 "must be a wide memory");
4970 // AliasLevel == 0 if we are organizing the memory states manually.
4971 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4972 } else {
4973 // make sure the stored slice is sane
4974 #ifdef ASSERT
4975 if (VMError::is_error_reported() || Node::in_dump()) {
4976 } else if (might_be_same(n, base_memory())) {
4977 // Give it a pass: It is a mostly harmless repetition of the base.
4978 // This can arise normally from node subsumption during optimization.
4979 } else {
4980 verify_memory_slice(this, alias_idx, n);
4981 }
4982 #endif
4983 }
4984 return n;
4985 }
4986
4987 //---------------------------set_memory_at-------------------------------------
4988 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4989 verify_memory_slice(this, alias_idx, n);
4990 Node* empty_mem = empty_memory();
4991 if (n == base_memory()) n = empty_mem; // collapse default
4992 uint need_req = alias_idx+1;
4993 if (req() < need_req) {
4994 if (n == empty_mem) return; // already the default, so do not grow me
4995 // grow the sparse array
4996 do {
4997 add_req(empty_mem);
4998 } while (req() < need_req);
4999 }
5000 set_req( alias_idx, n );
5001 }
5002
5003
5004
5005 //--------------------------iteration_setup------------------------------------
5006 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5007 if (other != NULL) {
5008 grow_to_match(other);
5009 // invariant: the finite support of mm2 is within mm->req()
5010 #ifdef ASSERT
5011 for (uint i = req(); i < other->req(); i++) {
5012 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5013 }
5014 #endif
5015 }
5016 // Replace spurious copies of base_memory by top.
5017 Node* base_mem = base_memory();
5018 if (base_mem != NULL && !base_mem->is_top()) {
5019 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5020 if (in(i) == base_mem)
5021 set_req(i, empty_memory());
5022 }
5023 }
5024 }
5025
5026 //---------------------------grow_to_match-------------------------------------
5027 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5028 Node* empty_mem = empty_memory();
5029 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5030 // look for the finite support of the other memory
5031 for (uint i = other->req(); --i >= req(); ) {
5032 if (other->in(i) != empty_mem) {
5033 uint new_len = i+1;
5034 while (req() < new_len) add_req(empty_mem);
5035 break;
5036 }
5037 }
5038 }
5039
5040 //---------------------------verify_sparse-------------------------------------
5041 #ifndef PRODUCT
5042 bool MergeMemNode::verify_sparse() const {
5043 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5044 Node* base_mem = base_memory();
5045 // The following can happen in degenerate cases, since empty==top.
5046 if (is_empty_memory(base_mem)) return true;
5047 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5048 assert(in(i) != NULL, "sane slice");
5049 if (in(i) == base_mem) return false; // should have been the sentinel value!
5050 }
5051 return true;
5052 }
5053
5054 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5055 Node* n;
5056 n = mm->in(idx);
5057 if (mem == n) return true; // might be empty_memory()
5058 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5059 if (mem == n) return true;
5060 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
5061 if (mem == n) return true;
5062 if (n == NULL) break;
5063 }
5064 return false;
5065 }
5066 #endif // !PRODUCT