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