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