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