1 /*
2 * Copyright (c) 1997, 2009, 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.
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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 // Portions of code courtesy of Clifford Click
26
27 // Optimization - Graph Style
28
29 #include "incls/_precompiled.incl"
30 #include "incls/_memnode.cpp.incl"
31
32 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
33
34 //=============================================================================
35 uint MemNode::size_of() const { return sizeof(*this); }
36
37 const TypePtr *MemNode::adr_type() const {
38 Node* adr = in(Address);
39 const TypePtr* cross_check = NULL;
40 DEBUG_ONLY(cross_check = _adr_type);
41 return calculate_adr_type(adr->bottom_type(), cross_check);
42 }
43
44 #ifndef PRODUCT
45 void MemNode::dump_spec(outputStream *st) const {
46 if (in(Address) == NULL) return; // node is dead
47 #ifndef ASSERT
48 // fake the missing field
49 const TypePtr* _adr_type = NULL;
50 if (in(Address) != NULL)
51 _adr_type = in(Address)->bottom_type()->isa_ptr();
52 #endif
53 dump_adr_type(this, _adr_type, st);
54
55 Compile* C = Compile::current();
56 if( C->alias_type(_adr_type)->is_volatile() )
57 st->print(" Volatile!");
58 }
59
60 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
61 st->print(" @");
62 if (adr_type == NULL) {
63 st->print("NULL");
64 } else {
65 adr_type->dump_on(st);
66 Compile* C = Compile::current();
67 Compile::AliasType* atp = NULL;
68 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
69 if (atp == NULL)
70 st->print(", idx=?\?;");
71 else if (atp->index() == Compile::AliasIdxBot)
72 st->print(", idx=Bot;");
73 else if (atp->index() == Compile::AliasIdxTop)
74 st->print(", idx=Top;");
75 else if (atp->index() == Compile::AliasIdxRaw)
76 st->print(", idx=Raw;");
77 else {
78 ciField* field = atp->field();
79 if (field) {
80 st->print(", name=");
81 field->print_name_on(st);
82 }
83 st->print(", idx=%d;", atp->index());
84 }
85 }
86 }
87
88 extern void print_alias_types();
89
90 #endif
91
92 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
93 const TypeOopPtr *tinst = t_adr->isa_oopptr();
94 if (tinst == NULL || !tinst->is_known_instance_field())
95 return mchain; // don't try to optimize non-instance types
96 uint instance_id = tinst->instance_id();
97 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
98 Node *prev = NULL;
99 Node *result = mchain;
100 while (prev != result) {
101 prev = result;
102 if (result == start_mem)
103 break; // hit one of our sentinels
104 // skip over a call which does not affect this memory slice
105 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
106 Node *proj_in = result->in(0);
107 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
108 break; // hit one of our sentinels
109 } else if (proj_in->is_Call()) {
110 CallNode *call = proj_in->as_Call();
111 if (!call->may_modify(t_adr, phase)) {
112 result = call->in(TypeFunc::Memory);
113 }
114 } else if (proj_in->is_Initialize()) {
115 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
116 // Stop if this is the initialization for the object instance which
117 // which contains this memory slice, otherwise skip over it.
118 if (alloc != NULL && alloc->_idx != instance_id) {
119 result = proj_in->in(TypeFunc::Memory);
120 }
121 } else if (proj_in->is_MemBar()) {
122 result = proj_in->in(TypeFunc::Memory);
123 } else {
124 assert(false, "unexpected projection");
125 }
126 } else if (result->is_ClearArray()) {
127 if (!ClearArrayNode::step_through(&result, instance_id, phase)) {
128 // Can not bypass initialization of the instance
129 // we are looking for.
130 break;
131 }
132 // Otherwise skip it (the call updated 'result' value).
133 } else if (result->is_MergeMem()) {
134 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
135 }
136 }
137 return result;
138 }
139
140 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
141 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
142 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
143 PhaseIterGVN *igvn = phase->is_IterGVN();
144 Node *result = mchain;
145 result = optimize_simple_memory_chain(result, t_adr, phase);
146 if (is_instance && igvn != NULL && result->is_Phi()) {
147 PhiNode *mphi = result->as_Phi();
148 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
149 const TypePtr *t = mphi->adr_type();
150 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
151 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
152 t->is_oopptr()->cast_to_exactness(true)
153 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
154 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
155 // clone the Phi with our address type
156 result = mphi->split_out_instance(t_adr, igvn);
157 } else {
158 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
159 }
160 }
161 return result;
162 }
163
164 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
165 uint alias_idx = phase->C->get_alias_index(tp);
166 Node *mem = mmem;
167 #ifdef ASSERT
168 {
169 // Check that current type is consistent with the alias index used during graph construction
170 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
171 bool consistent = adr_check == NULL || adr_check->empty() ||
172 phase->C->must_alias(adr_check, alias_idx );
173 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
174 if( !consistent && adr_check != NULL && !adr_check->empty() &&
175 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
176 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
177 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
178 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
179 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
180 // don't assert if it is dead code.
181 consistent = true;
182 }
183 if( !consistent ) {
184 st->print("alias_idx==%d, adr_check==", alias_idx);
185 if( adr_check == NULL ) {
186 st->print("NULL");
187 } else {
188 adr_check->dump();
189 }
190 st->cr();
191 print_alias_types();
192 assert(consistent, "adr_check must match alias idx");
193 }
194 }
195 #endif
196 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
197 // means an array I have not precisely typed yet. Do not do any
198 // alias stuff with it any time soon.
199 const TypeOopPtr *toop = tp->isa_oopptr();
200 if( tp->base() != Type::AnyPtr &&
201 !(toop &&
202 toop->klass() != NULL &&
203 toop->klass()->is_java_lang_Object() &&
204 toop->offset() == Type::OffsetBot) ) {
205 // compress paths and change unreachable cycles to TOP
206 // If not, we can update the input infinitely along a MergeMem cycle
207 // Equivalent code in PhiNode::Ideal
208 Node* m = phase->transform(mmem);
209 // If transformed to a MergeMem, get the desired slice
210 // Otherwise the returned node represents memory for every slice
211 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
212 // Update input if it is progress over what we have now
213 }
214 return mem;
215 }
216
217 //--------------------------Ideal_common---------------------------------------
218 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
219 // Unhook non-raw memories from complete (macro-expanded) initializations.
220 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
221 // If our control input is a dead region, kill all below the region
222 Node *ctl = in(MemNode::Control);
223 if (ctl && remove_dead_region(phase, can_reshape))
224 return this;
225 ctl = in(MemNode::Control);
226 // Don't bother trying to transform a dead node
227 if( ctl && ctl->is_top() ) return NodeSentinel;
228
229 PhaseIterGVN *igvn = phase->is_IterGVN();
230 // Wait if control on the worklist.
231 if (ctl && can_reshape && igvn != NULL) {
232 Node* bol = NULL;
233 Node* cmp = NULL;
234 if (ctl->in(0)->is_If()) {
235 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
236 bol = ctl->in(0)->in(1);
237 if (bol->is_Bool())
238 cmp = ctl->in(0)->in(1)->in(1);
239 }
240 if (igvn->_worklist.member(ctl) ||
241 (bol != NULL && igvn->_worklist.member(bol)) ||
242 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
243 // This control path may be dead.
244 // Delay this memory node transformation until the control is processed.
245 phase->is_IterGVN()->_worklist.push(this);
246 return NodeSentinel; // caller will return NULL
247 }
248 }
249 // Ignore if memory is dead, or self-loop
250 Node *mem = in(MemNode::Memory);
251 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
252 assert( mem != this, "dead loop in MemNode::Ideal" );
253
254 Node *address = in(MemNode::Address);
255 const Type *t_adr = phase->type( address );
256 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
257
258 if( can_reshape && igvn != NULL &&
259 (igvn->_worklist.member(address) ||
260 igvn->_worklist.size() > 0 && (phase->type(address) != adr_type())) ) {
261 // The address's base and type may change when the address is processed.
262 // Delay this mem node transformation until the address is processed.
263 phase->is_IterGVN()->_worklist.push(this);
264 return NodeSentinel; // caller will return NULL
265 }
266
267 // Do NOT remove or optimize the next lines: ensure a new alias index
268 // is allocated for an oop pointer type before Escape Analysis.
269 // Note: C++ will not remove it since the call has side effect.
270 if ( t_adr->isa_oopptr() ) {
271 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
272 }
273
274 #ifdef ASSERT
275 Node* base = NULL;
276 if (address->is_AddP())
277 base = address->in(AddPNode::Base);
278 assert(base == NULL || t_adr->isa_rawptr() ||
279 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
280 #endif
281
282 // Avoid independent memory operations
283 Node* old_mem = mem;
284
285 // The code which unhooks non-raw memories from complete (macro-expanded)
286 // initializations was removed. After macro-expansion all stores catched
287 // by Initialize node became raw stores and there is no information
288 // which memory slices they modify. So it is unsafe to move any memory
289 // operation above these stores. Also in most cases hooked non-raw memories
290 // were already unhooked by using information from detect_ptr_independence()
291 // and find_previous_store().
292
293 if (mem->is_MergeMem()) {
294 MergeMemNode* mmem = mem->as_MergeMem();
295 const TypePtr *tp = t_adr->is_ptr();
296
297 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
298 }
299
300 if (mem != old_mem) {
301 set_req(MemNode::Memory, mem);
302 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
303 return this;
304 }
305
306 // let the subclass continue analyzing...
307 return NULL;
308 }
309
310 // Helper function for proving some simple control dominations.
311 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
312 // Already assumes that 'dom' is available at 'sub', and that 'sub'
313 // is not a constant (dominated by the method's StartNode).
314 // Used by MemNode::find_previous_store to prove that the
315 // control input of a memory operation predates (dominates)
316 // an allocation it wants to look past.
317 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
318 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
319 return false; // Conservative answer for dead code
320
321 // Check 'dom'. Skip Proj and CatchProj nodes.
322 dom = dom->find_exact_control(dom);
323 if (dom == NULL || dom->is_top())
324 return false; // Conservative answer for dead code
325
326 if (dom == sub) {
327 // For the case when, for example, 'sub' is Initialize and the original
328 // 'dom' is Proj node of the 'sub'.
329 return false;
330 }
331
332 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
333 return true;
334
335 // 'dom' dominates 'sub' if its control edge and control edges
336 // of all its inputs dominate or equal to sub's control edge.
337
338 // Currently 'sub' is either Allocate, Initialize or Start nodes.
339 // Or Region for the check in LoadNode::Ideal();
340 // 'sub' should have sub->in(0) != NULL.
341 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
342 sub->is_Region(), "expecting only these nodes");
343
344 // Get control edge of 'sub'.
345 Node* orig_sub = sub;
346 sub = sub->find_exact_control(sub->in(0));
347 if (sub == NULL || sub->is_top())
348 return false; // Conservative answer for dead code
349
350 assert(sub->is_CFG(), "expecting control");
351
352 if (sub == dom)
353 return true;
354
355 if (sub->is_Start() || sub->is_Root())
356 return false;
357
358 {
359 // Check all control edges of 'dom'.
360
361 ResourceMark rm;
362 Arena* arena = Thread::current()->resource_area();
363 Node_List nlist(arena);
364 Unique_Node_List dom_list(arena);
365
366 dom_list.push(dom);
367 bool only_dominating_controls = false;
368
369 for (uint next = 0; next < dom_list.size(); next++) {
370 Node* n = dom_list.at(next);
371 if (n == orig_sub)
372 return false; // One of dom's inputs dominated by sub.
373 if (!n->is_CFG() && n->pinned()) {
374 // Check only own control edge for pinned non-control nodes.
375 n = n->find_exact_control(n->in(0));
376 if (n == NULL || n->is_top())
377 return false; // Conservative answer for dead code
378 assert(n->is_CFG(), "expecting control");
379 dom_list.push(n);
380 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
381 only_dominating_controls = true;
382 } else if (n->is_CFG()) {
383 if (n->dominates(sub, nlist))
384 only_dominating_controls = true;
385 else
386 return false;
387 } else {
388 // First, own control edge.
389 Node* m = n->find_exact_control(n->in(0));
390 if (m != NULL) {
391 if (m->is_top())
392 return false; // Conservative answer for dead code
393 dom_list.push(m);
394 }
395 // Now, the rest of edges.
396 uint cnt = n->req();
397 for (uint i = 1; i < cnt; i++) {
398 m = n->find_exact_control(n->in(i));
399 if (m == NULL || m->is_top())
400 continue;
401 dom_list.push(m);
402 }
403 }
404 }
405 return only_dominating_controls;
406 }
407 }
408
409 //---------------------detect_ptr_independence---------------------------------
410 // Used by MemNode::find_previous_store to prove that two base
411 // pointers are never equal.
412 // The pointers are accompanied by their associated allocations,
413 // if any, which have been previously discovered by the caller.
414 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
415 Node* p2, AllocateNode* a2,
416 PhaseTransform* phase) {
417 // Attempt to prove that these two pointers cannot be aliased.
418 // They may both manifestly be allocations, and they should differ.
419 // Or, if they are not both allocations, they can be distinct constants.
420 // Otherwise, one is an allocation and the other a pre-existing value.
421 if (a1 == NULL && a2 == NULL) { // neither an allocation
422 return (p1 != p2) && p1->is_Con() && p2->is_Con();
423 } else if (a1 != NULL && a2 != NULL) { // both allocations
424 return (a1 != a2);
425 } else if (a1 != NULL) { // one allocation a1
426 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
427 return all_controls_dominate(p2, a1);
428 } else { //(a2 != NULL) // one allocation a2
429 return all_controls_dominate(p1, a2);
430 }
431 return false;
432 }
433
434
435 // The logic for reordering loads and stores uses four steps:
436 // (a) Walk carefully past stores and initializations which we
437 // can prove are independent of this load.
438 // (b) Observe that the next memory state makes an exact match
439 // with self (load or store), and locate the relevant store.
440 // (c) Ensure that, if we were to wire self directly to the store,
441 // the optimizer would fold it up somehow.
442 // (d) Do the rewiring, and return, depending on some other part of
443 // the optimizer to fold up the load.
444 // This routine handles steps (a) and (b). Steps (c) and (d) are
445 // specific to loads and stores, so they are handled by the callers.
446 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
447 //
448 Node* MemNode::find_previous_store(PhaseTransform* phase) {
449 Node* ctrl = in(MemNode::Control);
450 Node* adr = in(MemNode::Address);
451 intptr_t offset = 0;
452 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
453 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
454
455 if (offset == Type::OffsetBot)
456 return NULL; // cannot unalias unless there are precise offsets
457
458 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
459
460 intptr_t size_in_bytes = memory_size();
461
462 Node* mem = in(MemNode::Memory); // start searching here...
463
464 int cnt = 50; // Cycle limiter
465 for (;;) { // While we can dance past unrelated stores...
466 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
467
468 if (mem->is_Store()) {
469 Node* st_adr = mem->in(MemNode::Address);
470 intptr_t st_offset = 0;
471 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
472 if (st_base == NULL)
473 break; // inscrutable pointer
474 if (st_offset != offset && st_offset != Type::OffsetBot) {
475 const int MAX_STORE = BytesPerLong;
476 if (st_offset >= offset + size_in_bytes ||
477 st_offset <= offset - MAX_STORE ||
478 st_offset <= offset - mem->as_Store()->memory_size()) {
479 // Success: The offsets are provably independent.
480 // (You may ask, why not just test st_offset != offset and be done?
481 // The answer is that stores of different sizes can co-exist
482 // in the same sequence of RawMem effects. We sometimes initialize
483 // a whole 'tile' of array elements with a single jint or jlong.)
484 mem = mem->in(MemNode::Memory);
485 continue; // (a) advance through independent store memory
486 }
487 }
488 if (st_base != base &&
489 detect_ptr_independence(base, alloc,
490 st_base,
491 AllocateNode::Ideal_allocation(st_base, phase),
492 phase)) {
493 // Success: The bases are provably independent.
494 mem = mem->in(MemNode::Memory);
495 continue; // (a) advance through independent store memory
496 }
497
498 // (b) At this point, if the bases or offsets do not agree, we lose,
499 // since we have not managed to prove 'this' and 'mem' independent.
500 if (st_base == base && st_offset == offset) {
501 return mem; // let caller handle steps (c), (d)
502 }
503
504 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
505 InitializeNode* st_init = mem->in(0)->as_Initialize();
506 AllocateNode* st_alloc = st_init->allocation();
507 if (st_alloc == NULL)
508 break; // something degenerated
509 bool known_identical = false;
510 bool known_independent = false;
511 if (alloc == st_alloc)
512 known_identical = true;
513 else if (alloc != NULL)
514 known_independent = true;
515 else if (all_controls_dominate(this, st_alloc))
516 known_independent = true;
517
518 if (known_independent) {
519 // The bases are provably independent: Either they are
520 // manifestly distinct allocations, or else the control
521 // of this load dominates the store's allocation.
522 int alias_idx = phase->C->get_alias_index(adr_type());
523 if (alias_idx == Compile::AliasIdxRaw) {
524 mem = st_alloc->in(TypeFunc::Memory);
525 } else {
526 mem = st_init->memory(alias_idx);
527 }
528 continue; // (a) advance through independent store memory
529 }
530
531 // (b) at this point, if we are not looking at a store initializing
532 // the same allocation we are loading from, we lose.
533 if (known_identical) {
534 // From caller, can_see_stored_value will consult find_captured_store.
535 return mem; // let caller handle steps (c), (d)
536 }
537
538 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
539 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
540 if (mem->is_Proj() && mem->in(0)->is_Call()) {
541 CallNode *call = mem->in(0)->as_Call();
542 if (!call->may_modify(addr_t, phase)) {
543 mem = call->in(TypeFunc::Memory);
544 continue; // (a) advance through independent call memory
545 }
546 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
547 mem = mem->in(0)->in(TypeFunc::Memory);
548 continue; // (a) advance through independent MemBar memory
549 } else if (mem->is_ClearArray()) {
550 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
551 // (the call updated 'mem' value)
552 continue; // (a) advance through independent allocation memory
553 } else {
554 // Can not bypass initialization of the instance
555 // we are looking for.
556 return mem;
557 }
558 } else if (mem->is_MergeMem()) {
559 int alias_idx = phase->C->get_alias_index(adr_type());
560 mem = mem->as_MergeMem()->memory_at(alias_idx);
561 continue; // (a) advance through independent MergeMem memory
562 }
563 }
564
565 // Unless there is an explicit 'continue', we must bail out here,
566 // because 'mem' is an inscrutable memory state (e.g., a call).
567 break;
568 }
569
570 return NULL; // bail out
571 }
572
573 //----------------------calculate_adr_type-------------------------------------
574 // Helper function. Notices when the given type of address hits top or bottom.
575 // Also, asserts a cross-check of the type against the expected address type.
576 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
577 if (t == Type::TOP) return NULL; // does not touch memory any more?
578 #ifdef PRODUCT
579 cross_check = NULL;
580 #else
581 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
582 #endif
583 const TypePtr* tp = t->isa_ptr();
584 if (tp == NULL) {
585 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
586 return TypePtr::BOTTOM; // touches lots of memory
587 } else {
588 #ifdef ASSERT
589 // %%%% [phh] We don't check the alias index if cross_check is
590 // TypeRawPtr::BOTTOM. Needs to be investigated.
591 if (cross_check != NULL &&
592 cross_check != TypePtr::BOTTOM &&
593 cross_check != TypeRawPtr::BOTTOM) {
594 // Recheck the alias index, to see if it has changed (due to a bug).
595 Compile* C = Compile::current();
596 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
597 "must stay in the original alias category");
598 // The type of the address must be contained in the adr_type,
599 // disregarding "null"-ness.
600 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
601 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
602 assert(cross_check->meet(tp_notnull) == cross_check,
603 "real address must not escape from expected memory type");
604 }
605 #endif
606 return tp;
607 }
608 }
609
610 //------------------------adr_phi_is_loop_invariant----------------------------
611 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
612 // loop is loop invariant. Make a quick traversal of Phi and associated
613 // CastPP nodes, looking to see if they are a closed group within the loop.
614 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
615 // The idea is that the phi-nest must boil down to only CastPP nodes
616 // with the same data. This implies that any path into the loop already
617 // includes such a CastPP, and so the original cast, whatever its input,
618 // must be covered by an equivalent cast, with an earlier control input.
619 ResourceMark rm;
620
621 // The loop entry input of the phi should be the unique dominating
622 // node for every Phi/CastPP in the loop.
623 Unique_Node_List closure;
624 closure.push(adr_phi->in(LoopNode::EntryControl));
625
626 // Add the phi node and the cast to the worklist.
627 Unique_Node_List worklist;
628 worklist.push(adr_phi);
629 if( cast != NULL ){
630 if( !cast->is_ConstraintCast() ) return false;
631 worklist.push(cast);
632 }
633
634 // Begin recursive walk of phi nodes.
635 while( worklist.size() ){
636 // Take a node off the worklist
637 Node *n = worklist.pop();
638 if( !closure.member(n) ){
639 // Add it to the closure.
640 closure.push(n);
641 // Make a sanity check to ensure we don't waste too much time here.
642 if( closure.size() > 20) return false;
643 // This node is OK if:
644 // - it is a cast of an identical value
645 // - or it is a phi node (then we add its inputs to the worklist)
646 // Otherwise, the node is not OK, and we presume the cast is not invariant
647 if( n->is_ConstraintCast() ){
648 worklist.push(n->in(1));
649 } else if( n->is_Phi() ) {
650 for( uint i = 1; i < n->req(); i++ ) {
651 worklist.push(n->in(i));
652 }
653 } else {
654 return false;
655 }
656 }
657 }
658
659 // Quit when the worklist is empty, and we've found no offending nodes.
660 return true;
661 }
662
663 //------------------------------Ideal_DU_postCCP-------------------------------
664 // Find any cast-away of null-ness and keep its control. Null cast-aways are
665 // going away in this pass and we need to make this memory op depend on the
666 // gating null check.
667 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
668 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
669 }
670
671 // I tried to leave the CastPP's in. This makes the graph more accurate in
672 // some sense; we get to keep around the knowledge that an oop is not-null
673 // after some test. Alas, the CastPP's interfere with GVN (some values are
674 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
675 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
676 // some of the more trivial cases in the optimizer. Removing more useless
677 // Phi's started allowing Loads to illegally float above null checks. I gave
678 // up on this approach. CNC 10/20/2000
679 // This static method may be called not from MemNode (EncodePNode calls it).
680 // Only the control edge of the node 'n' might be updated.
681 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
682 Node *skipped_cast = NULL;
683 // Need a null check? Regular static accesses do not because they are
684 // from constant addresses. Array ops are gated by the range check (which
685 // always includes a NULL check). Just check field ops.
686 if( n->in(MemNode::Control) == NULL ) {
687 // Scan upwards for the highest location we can place this memory op.
688 while( true ) {
689 switch( adr->Opcode() ) {
690
691 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
692 adr = adr->in(AddPNode::Base);
693 continue;
694
695 case Op_DecodeN: // No change to NULL-ness, so peek thru
696 adr = adr->in(1);
697 continue;
698
699 case Op_CastPP:
700 // If the CastPP is useless, just peek on through it.
701 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
702 // Remember the cast that we've peeked though. If we peek
703 // through more than one, then we end up remembering the highest
704 // one, that is, if in a loop, the one closest to the top.
705 skipped_cast = adr;
706 adr = adr->in(1);
707 continue;
708 }
709 // CastPP is going away in this pass! We need this memory op to be
710 // control-dependent on the test that is guarding the CastPP.
711 ccp->hash_delete(n);
712 n->set_req(MemNode::Control, adr->in(0));
713 ccp->hash_insert(n);
714 return n;
715
716 case Op_Phi:
717 // Attempt to float above a Phi to some dominating point.
718 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
719 // If we've already peeked through a Cast (which could have set the
720 // control), we can't float above a Phi, because the skipped Cast
721 // may not be loop invariant.
722 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
723 adr = adr->in(1);
724 continue;
725 }
726 }
727
728 // Intentional fallthrough!
729
730 // No obvious dominating point. The mem op is pinned below the Phi
731 // by the Phi itself. If the Phi goes away (no true value is merged)
732 // then the mem op can float, but not indefinitely. It must be pinned
733 // behind the controls leading to the Phi.
734 case Op_CheckCastPP:
735 // These usually stick around to change address type, however a
736 // useless one can be elided and we still need to pick up a control edge
737 if (adr->in(0) == NULL) {
738 // This CheckCastPP node has NO control and is likely useless. But we
739 // need check further up the ancestor chain for a control input to keep
740 // the node in place. 4959717.
741 skipped_cast = adr;
742 adr = adr->in(1);
743 continue;
744 }
745 ccp->hash_delete(n);
746 n->set_req(MemNode::Control, adr->in(0));
747 ccp->hash_insert(n);
748 return n;
749
750 // List of "safe" opcodes; those that implicitly block the memory
751 // op below any null check.
752 case Op_CastX2P: // no null checks on native pointers
753 case Op_Parm: // 'this' pointer is not null
754 case Op_LoadP: // Loading from within a klass
755 case Op_LoadN: // Loading from within a klass
756 case Op_LoadKlass: // Loading from within a klass
757 case Op_LoadNKlass: // Loading from within a klass
758 case Op_ConP: // Loading from a klass
759 case Op_ConN: // Loading from a klass
760 case Op_CreateEx: // Sucking up the guts of an exception oop
761 case Op_Con: // Reading from TLS
762 case Op_CMoveP: // CMoveP is pinned
763 case Op_CMoveN: // CMoveN is pinned
764 break; // No progress
765
766 case Op_Proj: // Direct call to an allocation routine
767 case Op_SCMemProj: // Memory state from store conditional ops
768 #ifdef ASSERT
769 {
770 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
771 const Node* call = adr->in(0);
772 if (call->is_CallJava()) {
773 const CallJavaNode* call_java = call->as_CallJava();
774 const TypeTuple *r = call_java->tf()->range();
775 assert(r->cnt() > TypeFunc::Parms, "must return value");
776 const Type* ret_type = r->field_at(TypeFunc::Parms);
777 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
778 // We further presume that this is one of
779 // new_instance_Java, new_array_Java, or
780 // the like, but do not assert for this.
781 } else if (call->is_Allocate()) {
782 // similar case to new_instance_Java, etc.
783 } else if (!call->is_CallLeaf()) {
784 // Projections from fetch_oop (OSR) are allowed as well.
785 ShouldNotReachHere();
786 }
787 }
788 #endif
789 break;
790 default:
791 ShouldNotReachHere();
792 }
793 break;
794 }
795 }
796
797 return NULL; // No progress
798 }
799
800
801 //=============================================================================
802 uint LoadNode::size_of() const { return sizeof(*this); }
803 uint LoadNode::cmp( const Node &n ) const
804 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
805 const Type *LoadNode::bottom_type() const { return _type; }
806 uint LoadNode::ideal_reg() const {
807 return Matcher::base2reg[_type->base()];
808 }
809
810 #ifndef PRODUCT
811 void LoadNode::dump_spec(outputStream *st) const {
812 MemNode::dump_spec(st);
813 if( !Verbose && !WizardMode ) {
814 // standard dump does this in Verbose and WizardMode
815 st->print(" #"); _type->dump_on(st);
816 }
817 }
818 #endif
819
820 #ifdef ASSERT
821 //----------------------------is_immutable_value-------------------------------
822 // Helper function to allow a raw load without control edge for some cases
823 bool LoadNode::is_immutable_value(Node* adr) {
824 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
825 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
826 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
827 in_bytes(JavaThread::osthread_offset())));
828 }
829 #endif
830
831 //----------------------------LoadNode::make-----------------------------------
832 // Polymorphic factory method:
833 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
834 Compile* C = gvn.C;
835
836 // sanity check the alias category against the created node type
837 assert(!(adr_type->isa_oopptr() &&
838 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
839 "use LoadKlassNode instead");
840 assert(!(adr_type->isa_aryptr() &&
841 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
842 "use LoadRangeNode instead");
843 // Check control edge of raw loads
844 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
845 // oop will be recorded in oop map if load crosses safepoint
846 rt->isa_oopptr() || is_immutable_value(adr),
847 "raw memory operations should have control edge");
848 switch (bt) {
849 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
850 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
851 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
852 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
853 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
854 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
855 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
856 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
857 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
858 case T_OBJECT:
859 #ifdef _LP64
860 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
861 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
862 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
863 } else
864 #endif
865 {
866 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
867 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
868 }
869 }
870 ShouldNotReachHere();
871 return (LoadNode*)NULL;
872 }
873
874 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
875 bool require_atomic = true;
876 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
877 }
878
879
880
881
882 //------------------------------hash-------------------------------------------
883 uint LoadNode::hash() const {
884 // unroll addition of interesting fields
885 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
886 }
887
888 //---------------------------can_see_stored_value------------------------------
889 // This routine exists to make sure this set of tests is done the same
890 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
891 // will change the graph shape in a way which makes memory alive twice at the
892 // same time (uses the Oracle model of aliasing), then some
893 // LoadXNode::Identity will fold things back to the equivalence-class model
894 // of aliasing.
895 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
896 Node* ld_adr = in(MemNode::Address);
897
898 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
899 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
900 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
901 atp->field() != NULL && !atp->field()->is_volatile()) {
902 uint alias_idx = atp->index();
903 bool final = atp->field()->is_final();
904 Node* result = NULL;
905 Node* current = st;
906 // Skip through chains of MemBarNodes checking the MergeMems for
907 // new states for the slice of this load. Stop once any other
908 // kind of node is encountered. Loads from final memory can skip
909 // through any kind of MemBar but normal loads shouldn't skip
910 // through MemBarAcquire since the could allow them to move out of
911 // a synchronized region.
912 while (current->is_Proj()) {
913 int opc = current->in(0)->Opcode();
914 if ((final && opc == Op_MemBarAcquire) ||
915 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
916 Node* mem = current->in(0)->in(TypeFunc::Memory);
917 if (mem->is_MergeMem()) {
918 MergeMemNode* merge = mem->as_MergeMem();
919 Node* new_st = merge->memory_at(alias_idx);
920 if (new_st == merge->base_memory()) {
921 // Keep searching
922 current = merge->base_memory();
923 continue;
924 }
925 // Save the new memory state for the slice and fall through
926 // to exit.
927 result = new_st;
928 }
929 }
930 break;
931 }
932 if (result != NULL) {
933 st = result;
934 }
935 }
936
937
938 // Loop around twice in the case Load -> Initialize -> Store.
939 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
940 for (int trip = 0; trip <= 1; trip++) {
941
942 if (st->is_Store()) {
943 Node* st_adr = st->in(MemNode::Address);
944 if (!phase->eqv(st_adr, ld_adr)) {
945 // Try harder before giving up... Match raw and non-raw pointers.
946 intptr_t st_off = 0;
947 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
948 if (alloc == NULL) return NULL;
949 intptr_t ld_off = 0;
950 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
951 if (alloc != allo2) return NULL;
952 if (ld_off != st_off) return NULL;
953 // At this point we have proven something like this setup:
954 // A = Allocate(...)
955 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
956 // S = StoreQ(, AddP(, A.Parm , #Off), V)
957 // (Actually, we haven't yet proven the Q's are the same.)
958 // In other words, we are loading from a casted version of
959 // the same pointer-and-offset that we stored to.
960 // Thus, we are able to replace L by V.
961 }
962 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
963 if (store_Opcode() != st->Opcode())
964 return NULL;
965 return st->in(MemNode::ValueIn);
966 }
967
968 intptr_t offset = 0; // scratch
969
970 // A load from a freshly-created object always returns zero.
971 // (This can happen after LoadNode::Ideal resets the load's memory input
972 // to find_captured_store, which returned InitializeNode::zero_memory.)
973 if (st->is_Proj() && st->in(0)->is_Allocate() &&
974 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
975 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
976 // return a zero value for the load's basic type
977 // (This is one of the few places where a generic PhaseTransform
978 // can create new nodes. Think of it as lazily manifesting
979 // virtually pre-existing constants.)
980 return phase->zerocon(memory_type());
981 }
982
983 // A load from an initialization barrier can match a captured store.
984 if (st->is_Proj() && st->in(0)->is_Initialize()) {
985 InitializeNode* init = st->in(0)->as_Initialize();
986 AllocateNode* alloc = init->allocation();
987 if (alloc != NULL &&
988 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
989 // examine a captured store value
990 st = init->find_captured_store(offset, memory_size(), phase);
991 if (st != NULL)
992 continue; // take one more trip around
993 }
994 }
995
996 break;
997 }
998
999 return NULL;
1000 }
1001
1002 //----------------------is_instance_field_load_with_local_phi------------------
1003 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1004 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1005 in(MemNode::Address)->is_AddP() ) {
1006 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1007 // Only instances.
1008 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1009 t_oop->offset() != Type::OffsetBot &&
1010 t_oop->offset() != Type::OffsetTop) {
1011 return true;
1012 }
1013 }
1014 return false;
1015 }
1016
1017 //------------------------------Identity---------------------------------------
1018 // Loads are identity if previous store is to same address
1019 Node *LoadNode::Identity( PhaseTransform *phase ) {
1020 // If the previous store-maker is the right kind of Store, and the store is
1021 // to the same address, then we are equal to the value stored.
1022 Node* mem = in(MemNode::Memory);
1023 Node* value = can_see_stored_value(mem, phase);
1024 if( value ) {
1025 // byte, short & char stores truncate naturally.
1026 // A load has to load the truncated value which requires
1027 // some sort of masking operation and that requires an
1028 // Ideal call instead of an Identity call.
1029 if (memory_size() < BytesPerInt) {
1030 // If the input to the store does not fit with the load's result type,
1031 // it must be truncated via an Ideal call.
1032 if (!phase->type(value)->higher_equal(phase->type(this)))
1033 return this;
1034 }
1035 // (This works even when value is a Con, but LoadNode::Value
1036 // usually runs first, producing the singleton type of the Con.)
1037 return value;
1038 }
1039
1040 // Search for an existing data phi which was generated before for the same
1041 // instance's field to avoid infinite generation of phis in a loop.
1042 Node *region = mem->in(0);
1043 if (is_instance_field_load_with_local_phi(region)) {
1044 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1045 int this_index = phase->C->get_alias_index(addr_t);
1046 int this_offset = addr_t->offset();
1047 int this_id = addr_t->is_oopptr()->instance_id();
1048 const Type* this_type = bottom_type();
1049 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1050 Node* phi = region->fast_out(i);
1051 if (phi->is_Phi() && phi != mem &&
1052 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1053 return phi;
1054 }
1055 }
1056 }
1057
1058 return this;
1059 }
1060
1061
1062 // Returns true if the AliasType refers to the field that holds the
1063 // cached box array. Currently only handles the IntegerCache case.
1064 static bool is_autobox_cache(Compile::AliasType* atp) {
1065 if (atp != NULL && atp->field() != NULL) {
1066 ciField* field = atp->field();
1067 ciSymbol* klass = field->holder()->name();
1068 if (field->name() == ciSymbol::cache_field_name() &&
1069 field->holder()->uses_default_loader() &&
1070 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1071 return true;
1072 }
1073 }
1074 return false;
1075 }
1076
1077 // Fetch the base value in the autobox array
1078 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1079 if (atp != NULL && atp->field() != NULL) {
1080 ciField* field = atp->field();
1081 ciSymbol* klass = field->holder()->name();
1082 if (field->name() == ciSymbol::cache_field_name() &&
1083 field->holder()->uses_default_loader() &&
1084 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1085 assert(field->is_constant(), "what?");
1086 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1087 // Fetch the box object at the base of the array and get its value
1088 ciInstance* box = array->obj_at(0)->as_instance();
1089 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1090 if (ik->nof_nonstatic_fields() == 1) {
1091 // This should be true nonstatic_field_at requires calling
1092 // nof_nonstatic_fields so check it anyway
1093 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1094 cache_offset = c.as_int();
1095 }
1096 return true;
1097 }
1098 }
1099 return false;
1100 }
1101
1102 // Returns true if the AliasType refers to the value field of an
1103 // autobox object. Currently only handles Integer.
1104 static bool is_autobox_object(Compile::AliasType* atp) {
1105 if (atp != NULL && atp->field() != NULL) {
1106 ciField* field = atp->field();
1107 ciSymbol* klass = field->holder()->name();
1108 if (field->name() == ciSymbol::value_name() &&
1109 field->holder()->uses_default_loader() &&
1110 klass == ciSymbol::java_lang_Integer()) {
1111 return true;
1112 }
1113 }
1114 return false;
1115 }
1116
1117
1118 // We're loading from an object which has autobox behaviour.
1119 // If this object is result of a valueOf call we'll have a phi
1120 // merging a newly allocated object and a load from the cache.
1121 // We want to replace this load with the original incoming
1122 // argument to the valueOf call.
1123 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1124 Node* base = in(Address)->in(AddPNode::Base);
1125 if (base->is_Phi() && base->req() == 3) {
1126 AllocateNode* allocation = NULL;
1127 int allocation_index = -1;
1128 int load_index = -1;
1129 for (uint i = 1; i < base->req(); i++) {
1130 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1131 if (allocation != NULL) {
1132 allocation_index = i;
1133 load_index = 3 - allocation_index;
1134 break;
1135 }
1136 }
1137 bool has_load = ( allocation != NULL &&
1138 (base->in(load_index)->is_Load() ||
1139 base->in(load_index)->is_DecodeN() &&
1140 base->in(load_index)->in(1)->is_Load()) );
1141 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1142 // Push the loads from the phi that comes from valueOf up
1143 // through it to allow elimination of the loads and the recovery
1144 // of the original value.
1145 Node* mem_phi = in(Memory);
1146 Node* offset = in(Address)->in(AddPNode::Offset);
1147 Node* region = base->in(0);
1148
1149 Node* in1 = clone();
1150 Node* in1_addr = in1->in(Address)->clone();
1151 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1152 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1153 in1_addr->set_req(AddPNode::Offset, offset);
1154 in1->set_req(0, region->in(allocation_index));
1155 in1->set_req(Address, in1_addr);
1156 in1->set_req(Memory, mem_phi->in(allocation_index));
1157
1158 Node* in2 = clone();
1159 Node* in2_addr = in2->in(Address)->clone();
1160 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1161 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1162 in2_addr->set_req(AddPNode::Offset, offset);
1163 in2->set_req(0, region->in(load_index));
1164 in2->set_req(Address, in2_addr);
1165 in2->set_req(Memory, mem_phi->in(load_index));
1166
1167 in1_addr = phase->transform(in1_addr);
1168 in1 = phase->transform(in1);
1169 in2_addr = phase->transform(in2_addr);
1170 in2 = phase->transform(in2);
1171
1172 PhiNode* result = PhiNode::make_blank(region, this);
1173 result->set_req(allocation_index, in1);
1174 result->set_req(load_index, in2);
1175 return result;
1176 }
1177 } else if (base->is_Load() ||
1178 base->is_DecodeN() && base->in(1)->is_Load()) {
1179 if (base->is_DecodeN()) {
1180 // Get LoadN node which loads cached Integer object
1181 base = base->in(1);
1182 }
1183 // Eliminate the load of Integer.value for integers from the cache
1184 // array by deriving the value from the index into the array.
1185 // Capture the offset of the load and then reverse the computation.
1186 Node* load_base = base->in(Address)->in(AddPNode::Base);
1187 if (load_base->is_DecodeN()) {
1188 // Get LoadN node which loads IntegerCache.cache field
1189 load_base = load_base->in(1);
1190 }
1191 if (load_base != NULL) {
1192 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1193 intptr_t cache_offset;
1194 int shift = -1;
1195 Node* cache = NULL;
1196 if (is_autobox_cache(atp)) {
1197 shift = exact_log2(type2aelembytes(T_OBJECT));
1198 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1199 }
1200 if (cache != NULL && base->in(Address)->is_AddP()) {
1201 Node* elements[4];
1202 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1203 int cache_low;
1204 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1205 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1206 // Add up all the offsets making of the address of the load
1207 Node* result = elements[0];
1208 for (int i = 1; i < count; i++) {
1209 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1210 }
1211 // Remove the constant offset from the address and then
1212 // remove the scaling of the offset to recover the original index.
1213 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1214 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1215 // Peel the shift off directly but wrap it in a dummy node
1216 // since Ideal can't return existing nodes
1217 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1218 } else {
1219 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1220 }
1221 #ifdef _LP64
1222 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1223 #endif
1224 return result;
1225 }
1226 }
1227 }
1228 }
1229 return NULL;
1230 }
1231
1232 //------------------------------split_through_phi------------------------------
1233 // Split instance field load through Phi.
1234 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1235 Node* mem = in(MemNode::Memory);
1236 Node* address = in(MemNode::Address);
1237 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1238 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1239
1240 assert(mem->is_Phi() && (t_oop != NULL) &&
1241 t_oop->is_known_instance_field(), "invalide conditions");
1242
1243 Node *region = mem->in(0);
1244 if (region == NULL) {
1245 return NULL; // Wait stable graph
1246 }
1247 uint cnt = mem->req();
1248 for( uint i = 1; i < cnt; i++ ) {
1249 Node *in = mem->in(i);
1250 if( in == NULL ) {
1251 return NULL; // Wait stable graph
1252 }
1253 }
1254 // Check for loop invariant.
1255 if (cnt == 3) {
1256 for( uint i = 1; i < cnt; i++ ) {
1257 Node *in = mem->in(i);
1258 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1259 if (m == mem) {
1260 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1261 return this;
1262 }
1263 }
1264 }
1265 // Split through Phi (see original code in loopopts.cpp).
1266 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1267
1268 // Do nothing here if Identity will find a value
1269 // (to avoid infinite chain of value phis generation).
1270 if ( !phase->eqv(this, this->Identity(phase)) )
1271 return NULL;
1272
1273 // Skip the split if the region dominates some control edge of the address.
1274 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1275 return NULL;
1276
1277 const Type* this_type = this->bottom_type();
1278 int this_index = phase->C->get_alias_index(addr_t);
1279 int this_offset = addr_t->offset();
1280 int this_iid = addr_t->is_oopptr()->instance_id();
1281 int wins = 0;
1282 PhaseIterGVN *igvn = phase->is_IterGVN();
1283 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1284 for( uint i = 1; i < region->req(); i++ ) {
1285 Node *x;
1286 Node* the_clone = NULL;
1287 if( region->in(i) == phase->C->top() ) {
1288 x = phase->C->top(); // Dead path? Use a dead data op
1289 } else {
1290 x = this->clone(); // Else clone up the data op
1291 the_clone = x; // Remember for possible deletion.
1292 // Alter data node to use pre-phi inputs
1293 if( this->in(0) == region ) {
1294 x->set_req( 0, region->in(i) );
1295 } else {
1296 x->set_req( 0, NULL );
1297 }
1298 for( uint j = 1; j < this->req(); j++ ) {
1299 Node *in = this->in(j);
1300 if( in->is_Phi() && in->in(0) == region )
1301 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1302 }
1303 }
1304 // Check for a 'win' on some paths
1305 const Type *t = x->Value(igvn);
1306
1307 bool singleton = t->singleton();
1308
1309 // See comments in PhaseIdealLoop::split_thru_phi().
1310 if( singleton && t == Type::TOP ) {
1311 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1312 }
1313
1314 if( singleton ) {
1315 wins++;
1316 x = igvn->makecon(t);
1317 } else {
1318 // We now call Identity to try to simplify the cloned node.
1319 // Note that some Identity methods call phase->type(this).
1320 // Make sure that the type array is big enough for
1321 // our new node, even though we may throw the node away.
1322 // (This tweaking with igvn only works because x is a new node.)
1323 igvn->set_type(x, t);
1324 // If x is a TypeNode, capture any more-precise type permanently into Node
1325 // otherwise it will be not updated during igvn->transform since
1326 // igvn->type(x) is set to x->Value() already.
1327 x->raise_bottom_type(t);
1328 Node *y = x->Identity(igvn);
1329 if( y != x ) {
1330 wins++;
1331 x = y;
1332 } else {
1333 y = igvn->hash_find(x);
1334 if( y ) {
1335 wins++;
1336 x = y;
1337 } else {
1338 // Else x is a new node we are keeping
1339 // We do not need register_new_node_with_optimizer
1340 // because set_type has already been called.
1341 igvn->_worklist.push(x);
1342 }
1343 }
1344 }
1345 if (x != the_clone && the_clone != NULL)
1346 igvn->remove_dead_node(the_clone);
1347 phi->set_req(i, x);
1348 }
1349 if( wins > 0 ) {
1350 // Record Phi
1351 igvn->register_new_node_with_optimizer(phi);
1352 return phi;
1353 }
1354 igvn->remove_dead_node(phi);
1355 return NULL;
1356 }
1357
1358 //------------------------------Ideal------------------------------------------
1359 // If the load is from Field memory and the pointer is non-null, we can
1360 // zero out the control input.
1361 // If the offset is constant and the base is an object allocation,
1362 // try to hook me up to the exact initializing store.
1363 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1364 Node* p = MemNode::Ideal_common(phase, can_reshape);
1365 if (p) return (p == NodeSentinel) ? NULL : p;
1366
1367 Node* ctrl = in(MemNode::Control);
1368 Node* address = in(MemNode::Address);
1369
1370 // Skip up past a SafePoint control. Cannot do this for Stores because
1371 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1372 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1373 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1374 ctrl = ctrl->in(0);
1375 set_req(MemNode::Control,ctrl);
1376 }
1377
1378 intptr_t ignore = 0;
1379 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1380 if (base != NULL
1381 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1382 // Check for useless control edge in some common special cases
1383 if (in(MemNode::Control) != NULL
1384 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1385 && all_controls_dominate(base, phase->C->start())) {
1386 // A method-invariant, non-null address (constant or 'this' argument).
1387 set_req(MemNode::Control, NULL);
1388 }
1389
1390 if (EliminateAutoBox && can_reshape) {
1391 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1392 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1393 if (is_autobox_object(atp)) {
1394 Node* result = eliminate_autobox(phase);
1395 if (result != NULL) return result;
1396 }
1397 }
1398 }
1399
1400 Node* mem = in(MemNode::Memory);
1401 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1402
1403 if (addr_t != NULL) {
1404 // try to optimize our memory input
1405 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1406 if (opt_mem != mem) {
1407 set_req(MemNode::Memory, opt_mem);
1408 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1409 return this;
1410 }
1411 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1412 if (can_reshape && opt_mem->is_Phi() &&
1413 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1414 // Split instance field load through Phi.
1415 Node* result = split_through_phi(phase);
1416 if (result != NULL) return result;
1417 }
1418 }
1419
1420 // Check for prior store with a different base or offset; make Load
1421 // independent. Skip through any number of them. Bail out if the stores
1422 // are in an endless dead cycle and report no progress. This is a key
1423 // transform for Reflection. However, if after skipping through the Stores
1424 // we can't then fold up against a prior store do NOT do the transform as
1425 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1426 // array memory alive twice: once for the hoisted Load and again after the
1427 // bypassed Store. This situation only works if EVERYBODY who does
1428 // anti-dependence work knows how to bypass. I.e. we need all
1429 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1430 // the alias index stuff. So instead, peek through Stores and IFF we can
1431 // fold up, do so.
1432 Node* prev_mem = find_previous_store(phase);
1433 // Steps (a), (b): Walk past independent stores to find an exact match.
1434 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1435 // (c) See if we can fold up on the spot, but don't fold up here.
1436 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1437 // just return a prior value, which is done by Identity calls.
1438 if (can_see_stored_value(prev_mem, phase)) {
1439 // Make ready for step (d):
1440 set_req(MemNode::Memory, prev_mem);
1441 return this;
1442 }
1443 }
1444
1445 return NULL; // No further progress
1446 }
1447
1448 // Helper to recognize certain Klass fields which are invariant across
1449 // some group of array types (e.g., int[] or all T[] where T < Object).
1450 const Type*
1451 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1452 ciKlass* klass) const {
1453 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1454 // The field is Klass::_modifier_flags. Return its (constant) value.
1455 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1456 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1457 return TypeInt::make(klass->modifier_flags());
1458 }
1459 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1460 // The field is Klass::_access_flags. Return its (constant) value.
1461 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1462 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1463 return TypeInt::make(klass->access_flags());
1464 }
1465 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1466 // The field is Klass::_layout_helper. Return its constant value if known.
1467 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1468 return TypeInt::make(klass->layout_helper());
1469 }
1470
1471 // No match.
1472 return NULL;
1473 }
1474
1475 //------------------------------Value-----------------------------------------
1476 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1477 // Either input is TOP ==> the result is TOP
1478 Node* mem = in(MemNode::Memory);
1479 const Type *t1 = phase->type(mem);
1480 if (t1 == Type::TOP) return Type::TOP;
1481 Node* adr = in(MemNode::Address);
1482 const TypePtr* tp = phase->type(adr)->isa_ptr();
1483 if (tp == NULL || tp->empty()) return Type::TOP;
1484 int off = tp->offset();
1485 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1486
1487 // Try to guess loaded type from pointer type
1488 if (tp->base() == Type::AryPtr) {
1489 const Type *t = tp->is_aryptr()->elem();
1490 // Don't do this for integer types. There is only potential profit if
1491 // the element type t is lower than _type; that is, for int types, if _type is
1492 // more restrictive than t. This only happens here if one is short and the other
1493 // char (both 16 bits), and in those cases we've made an intentional decision
1494 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1495 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1496 //
1497 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1498 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1499 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1500 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1501 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1502 // In fact, that could have been the original type of p1, and p1 could have
1503 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1504 // expression (LShiftL quux 3) independently optimized to the constant 8.
1505 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1506 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1507 // t might actually be lower than _type, if _type is a unique
1508 // concrete subclass of abstract class t.
1509 // Make sure the reference is not into the header, by comparing
1510 // the offset against the offset of the start of the array's data.
1511 // Different array types begin at slightly different offsets (12 vs. 16).
1512 // We choose T_BYTE as an example base type that is least restrictive
1513 // as to alignment, which will therefore produce the smallest
1514 // possible base offset.
1515 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1516 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1517 const Type* jt = t->join(_type);
1518 // In any case, do not allow the join, per se, to empty out the type.
1519 if (jt->empty() && !t->empty()) {
1520 // This can happen if a interface-typed array narrows to a class type.
1521 jt = _type;
1522 }
1523
1524 if (EliminateAutoBox && adr->is_AddP()) {
1525 // The pointers in the autobox arrays are always non-null
1526 Node* base = adr->in(AddPNode::Base);
1527 if (base != NULL &&
1528 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1529 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1530 if (is_autobox_cache(atp)) {
1531 return jt->join(TypePtr::NOTNULL)->is_ptr();
1532 }
1533 }
1534 }
1535 return jt;
1536 }
1537 }
1538 } else if (tp->base() == Type::InstPtr) {
1539 const TypeInstPtr* tinst = tp->is_instptr();
1540 ciKlass* klass = tinst->klass();
1541 assert( off != Type::OffsetBot ||
1542 // arrays can be cast to Objects
1543 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1544 // unsafe field access may not have a constant offset
1545 phase->C->has_unsafe_access(),
1546 "Field accesses must be precise" );
1547 // For oop loads, we expect the _type to be precise
1548 if (OptimizeStringConcat && klass == phase->C->env()->String_klass() &&
1549 adr->is_AddP() && off != Type::OffsetBot) {
1550 // For constant Strings treat the fields as compile time constants.
1551 Node* base = adr->in(AddPNode::Base);
1552 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1553 if (t != NULL && t->singleton()) {
1554 ciObject* string = t->const_oop();
1555 ciConstant constant = string->as_instance()->field_value_by_offset(off);
1556 if (constant.basic_type() == T_INT) {
1557 return TypeInt::make(constant.as_int());
1558 } else if (constant.basic_type() == T_ARRAY) {
1559 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1560 return TypeNarrowOop::make_from_constant(constant.as_object());
1561 } else {
1562 return TypeOopPtr::make_from_constant(constant.as_object());
1563 }
1564 }
1565 }
1566 }
1567 } else if (tp->base() == Type::KlassPtr) {
1568 assert( off != Type::OffsetBot ||
1569 // arrays can be cast to Objects
1570 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1571 // also allow array-loading from the primary supertype
1572 // array during subtype checks
1573 Opcode() == Op_LoadKlass,
1574 "Field accesses must be precise" );
1575 // For klass/static loads, we expect the _type to be precise
1576 }
1577
1578 const TypeKlassPtr *tkls = tp->isa_klassptr();
1579 if (tkls != NULL && !StressReflectiveCode) {
1580 ciKlass* klass = tkls->klass();
1581 if (klass->is_loaded() && tkls->klass_is_exact()) {
1582 // We are loading a field from a Klass metaobject whose identity
1583 // is known at compile time (the type is "exact" or "precise").
1584 // Check for fields we know are maintained as constants by the VM.
1585 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1586 // The field is Klass::_super_check_offset. Return its (constant) value.
1587 // (Folds up type checking code.)
1588 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1589 return TypeInt::make(klass->super_check_offset());
1590 }
1591 // Compute index into primary_supers array
1592 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1593 // Check for overflowing; use unsigned compare to handle the negative case.
1594 if( depth < ciKlass::primary_super_limit() ) {
1595 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1596 // (Folds up type checking code.)
1597 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1598 ciKlass *ss = klass->super_of_depth(depth);
1599 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1600 }
1601 const Type* aift = load_array_final_field(tkls, klass);
1602 if (aift != NULL) return aift;
1603 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1604 && klass->is_array_klass()) {
1605 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1606 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1607 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1608 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1609 }
1610 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1611 // The field is Klass::_java_mirror. Return its (constant) value.
1612 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1613 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1614 return TypeInstPtr::make(klass->java_mirror());
1615 }
1616 }
1617
1618 // We can still check if we are loading from the primary_supers array at a
1619 // shallow enough depth. Even though the klass is not exact, entries less
1620 // than or equal to its super depth are correct.
1621 if (klass->is_loaded() ) {
1622 ciType *inner = klass->klass();
1623 while( inner->is_obj_array_klass() )
1624 inner = inner->as_obj_array_klass()->base_element_type();
1625 if( inner->is_instance_klass() &&
1626 !inner->as_instance_klass()->flags().is_interface() ) {
1627 // Compute index into primary_supers array
1628 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1629 // Check for overflowing; use unsigned compare to handle the negative case.
1630 if( depth < ciKlass::primary_super_limit() &&
1631 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1632 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1633 // (Folds up type checking code.)
1634 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1635 ciKlass *ss = klass->super_of_depth(depth);
1636 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1637 }
1638 }
1639 }
1640
1641 // If the type is enough to determine that the thing is not an array,
1642 // we can give the layout_helper a positive interval type.
1643 // This will help short-circuit some reflective code.
1644 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1645 && !klass->is_array_klass() // not directly typed as an array
1646 && !klass->is_interface() // specifically not Serializable & Cloneable
1647 && !klass->is_java_lang_Object() // not the supertype of all T[]
1648 ) {
1649 // Note: When interfaces are reliable, we can narrow the interface
1650 // test to (klass != Serializable && klass != Cloneable).
1651 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1652 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1653 // The key property of this type is that it folds up tests
1654 // for array-ness, since it proves that the layout_helper is positive.
1655 // Thus, a generic value like the basic object layout helper works fine.
1656 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1657 }
1658 }
1659
1660 // If we are loading from a freshly-allocated object, produce a zero,
1661 // if the load is provably beyond the header of the object.
1662 // (Also allow a variable load from a fresh array to produce zero.)
1663 if (ReduceFieldZeroing) {
1664 Node* value = can_see_stored_value(mem,phase);
1665 if (value != NULL && value->is_Con())
1666 return value->bottom_type();
1667 }
1668
1669 const TypeOopPtr *tinst = tp->isa_oopptr();
1670 if (tinst != NULL && tinst->is_known_instance_field()) {
1671 // If we have an instance type and our memory input is the
1672 // programs's initial memory state, there is no matching store,
1673 // so just return a zero of the appropriate type
1674 Node *mem = in(MemNode::Memory);
1675 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1676 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1677 return Type::get_zero_type(_type->basic_type());
1678 }
1679 }
1680 return _type;
1681 }
1682
1683 //------------------------------match_edge-------------------------------------
1684 // Do we Match on this edge index or not? Match only the address.
1685 uint LoadNode::match_edge(uint idx) const {
1686 return idx == MemNode::Address;
1687 }
1688
1689 //--------------------------LoadBNode::Ideal--------------------------------------
1690 //
1691 // If the previous store is to the same address as this load,
1692 // and the value stored was larger than a byte, replace this load
1693 // with the value stored truncated to a byte. If no truncation is
1694 // needed, the replacement is done in LoadNode::Identity().
1695 //
1696 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1697 Node* mem = in(MemNode::Memory);
1698 Node* value = can_see_stored_value(mem,phase);
1699 if( value && !phase->type(value)->higher_equal( _type ) ) {
1700 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1701 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1702 }
1703 // Identity call will handle the case where truncation is not needed.
1704 return LoadNode::Ideal(phase, can_reshape);
1705 }
1706
1707 //--------------------------LoadUBNode::Ideal-------------------------------------
1708 //
1709 // If the previous store is to the same address as this load,
1710 // and the value stored was larger than a byte, replace this load
1711 // with the value stored truncated to a byte. If no truncation is
1712 // needed, the replacement is done in LoadNode::Identity().
1713 //
1714 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1715 Node* mem = in(MemNode::Memory);
1716 Node* value = can_see_stored_value(mem, phase);
1717 if (value && !phase->type(value)->higher_equal(_type))
1718 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1719 // Identity call will handle the case where truncation is not needed.
1720 return LoadNode::Ideal(phase, can_reshape);
1721 }
1722
1723 //--------------------------LoadUSNode::Ideal-------------------------------------
1724 //
1725 // If the previous store is to the same address as this load,
1726 // and the value stored was larger than a char, replace this load
1727 // with the value stored truncated to a char. If no truncation is
1728 // needed, the replacement is done in LoadNode::Identity().
1729 //
1730 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1731 Node* mem = in(MemNode::Memory);
1732 Node* value = can_see_stored_value(mem,phase);
1733 if( value && !phase->type(value)->higher_equal( _type ) )
1734 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1735 // Identity call will handle the case where truncation is not needed.
1736 return LoadNode::Ideal(phase, can_reshape);
1737 }
1738
1739 //--------------------------LoadSNode::Ideal--------------------------------------
1740 //
1741 // If the previous store is to the same address as this load,
1742 // and the value stored was larger than a short, replace this load
1743 // with the value stored truncated to a short. If no truncation is
1744 // needed, the replacement is done in LoadNode::Identity().
1745 //
1746 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1747 Node* mem = in(MemNode::Memory);
1748 Node* value = can_see_stored_value(mem,phase);
1749 if( value && !phase->type(value)->higher_equal( _type ) ) {
1750 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1751 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1752 }
1753 // Identity call will handle the case where truncation is not needed.
1754 return LoadNode::Ideal(phase, can_reshape);
1755 }
1756
1757 //=============================================================================
1758 //----------------------------LoadKlassNode::make------------------------------
1759 // Polymorphic factory method:
1760 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1761 Compile* C = gvn.C;
1762 Node *ctl = NULL;
1763 // sanity check the alias category against the created node type
1764 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1765 assert(adr_type != NULL, "expecting TypeOopPtr");
1766 #ifdef _LP64
1767 if (adr_type->is_ptr_to_narrowoop()) {
1768 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1769 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1770 }
1771 #endif
1772 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1773 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1774 }
1775
1776 //------------------------------Value------------------------------------------
1777 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1778 return klass_value_common(phase);
1779 }
1780
1781 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1782 // Either input is TOP ==> the result is TOP
1783 const Type *t1 = phase->type( in(MemNode::Memory) );
1784 if (t1 == Type::TOP) return Type::TOP;
1785 Node *adr = in(MemNode::Address);
1786 const Type *t2 = phase->type( adr );
1787 if (t2 == Type::TOP) return Type::TOP;
1788 const TypePtr *tp = t2->is_ptr();
1789 if (TypePtr::above_centerline(tp->ptr()) ||
1790 tp->ptr() == TypePtr::Null) return Type::TOP;
1791
1792 // Return a more precise klass, if possible
1793 const TypeInstPtr *tinst = tp->isa_instptr();
1794 if (tinst != NULL) {
1795 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1796 int offset = tinst->offset();
1797 if (ik == phase->C->env()->Class_klass()
1798 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1799 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1800 // We are loading a special hidden field from a Class mirror object,
1801 // the field which points to the VM's Klass metaobject.
1802 ciType* t = tinst->java_mirror_type();
1803 // java_mirror_type returns non-null for compile-time Class constants.
1804 if (t != NULL) {
1805 // constant oop => constant klass
1806 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1807 return TypeKlassPtr::make(ciArrayKlass::make(t));
1808 }
1809 if (!t->is_klass()) {
1810 // a primitive Class (e.g., int.class) has NULL for a klass field
1811 return TypePtr::NULL_PTR;
1812 }
1813 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1814 return TypeKlassPtr::make(t->as_klass());
1815 }
1816 // non-constant mirror, so we can't tell what's going on
1817 }
1818 if( !ik->is_loaded() )
1819 return _type; // Bail out if not loaded
1820 if (offset == oopDesc::klass_offset_in_bytes()) {
1821 if (tinst->klass_is_exact()) {
1822 return TypeKlassPtr::make(ik);
1823 }
1824 // See if we can become precise: no subklasses and no interface
1825 // (Note: We need to support verified interfaces.)
1826 if (!ik->is_interface() && !ik->has_subklass()) {
1827 //assert(!UseExactTypes, "this code should be useless with exact types");
1828 // Add a dependence; if any subclass added we need to recompile
1829 if (!ik->is_final()) {
1830 // %%% should use stronger assert_unique_concrete_subtype instead
1831 phase->C->dependencies()->assert_leaf_type(ik);
1832 }
1833 // Return precise klass
1834 return TypeKlassPtr::make(ik);
1835 }
1836
1837 // Return root of possible klass
1838 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1839 }
1840 }
1841
1842 // Check for loading klass from an array
1843 const TypeAryPtr *tary = tp->isa_aryptr();
1844 if( tary != NULL ) {
1845 ciKlass *tary_klass = tary->klass();
1846 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1847 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1848 if (tary->klass_is_exact()) {
1849 return TypeKlassPtr::make(tary_klass);
1850 }
1851 ciArrayKlass *ak = tary->klass()->as_array_klass();
1852 // If the klass is an object array, we defer the question to the
1853 // array component klass.
1854 if( ak->is_obj_array_klass() ) {
1855 assert( ak->is_loaded(), "" );
1856 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1857 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1858 ciInstanceKlass* ik = base_k->as_instance_klass();
1859 // See if we can become precise: no subklasses and no interface
1860 if (!ik->is_interface() && !ik->has_subklass()) {
1861 //assert(!UseExactTypes, "this code should be useless with exact types");
1862 // Add a dependence; if any subclass added we need to recompile
1863 if (!ik->is_final()) {
1864 phase->C->dependencies()->assert_leaf_type(ik);
1865 }
1866 // Return precise array klass
1867 return TypeKlassPtr::make(ak);
1868 }
1869 }
1870 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1871 } else { // Found a type-array?
1872 //assert(!UseExactTypes, "this code should be useless with exact types");
1873 assert( ak->is_type_array_klass(), "" );
1874 return TypeKlassPtr::make(ak); // These are always precise
1875 }
1876 }
1877 }
1878
1879 // Check for loading klass from an array klass
1880 const TypeKlassPtr *tkls = tp->isa_klassptr();
1881 if (tkls != NULL && !StressReflectiveCode) {
1882 ciKlass* klass = tkls->klass();
1883 if( !klass->is_loaded() )
1884 return _type; // Bail out if not loaded
1885 if( klass->is_obj_array_klass() &&
1886 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1887 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1888 // // Always returning precise element type is incorrect,
1889 // // e.g., element type could be object and array may contain strings
1890 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1891
1892 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1893 // according to the element type's subclassing.
1894 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1895 }
1896 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1897 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1898 ciKlass* sup = klass->as_instance_klass()->super();
1899 // The field is Klass::_super. Return its (constant) value.
1900 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1901 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1902 }
1903 }
1904
1905 // Bailout case
1906 return LoadNode::Value(phase);
1907 }
1908
1909 //------------------------------Identity---------------------------------------
1910 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1911 // Also feed through the klass in Allocate(...klass...)._klass.
1912 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1913 return klass_identity_common(phase);
1914 }
1915
1916 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1917 Node* x = LoadNode::Identity(phase);
1918 if (x != this) return x;
1919
1920 // Take apart the address into an oop and and offset.
1921 // Return 'this' if we cannot.
1922 Node* adr = in(MemNode::Address);
1923 intptr_t offset = 0;
1924 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1925 if (base == NULL) return this;
1926 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1927 if (toop == NULL) return this;
1928
1929 // We can fetch the klass directly through an AllocateNode.
1930 // This works even if the klass is not constant (clone or newArray).
1931 if (offset == oopDesc::klass_offset_in_bytes()) {
1932 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1933 if (allocated_klass != NULL) {
1934 return allocated_klass;
1935 }
1936 }
1937
1938 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1939 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1940 // See inline_native_Class_query for occurrences of these patterns.
1941 // Java Example: x.getClass().isAssignableFrom(y)
1942 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1943 //
1944 // This improves reflective code, often making the Class
1945 // mirror go completely dead. (Current exception: Class
1946 // mirrors may appear in debug info, but we could clean them out by
1947 // introducing a new debug info operator for klassOop.java_mirror).
1948 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1949 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1950 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1951 // We are loading a special hidden field from a Class mirror,
1952 // the field which points to its Klass or arrayKlass metaobject.
1953 if (base->is_Load()) {
1954 Node* adr2 = base->in(MemNode::Address);
1955 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1956 if (tkls != NULL && !tkls->empty()
1957 && (tkls->klass()->is_instance_klass() ||
1958 tkls->klass()->is_array_klass())
1959 && adr2->is_AddP()
1960 ) {
1961 int mirror_field = Klass::java_mirror_offset_in_bytes();
1962 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1963 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1964 }
1965 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1966 return adr2->in(AddPNode::Base);
1967 }
1968 }
1969 }
1970 }
1971
1972 return this;
1973 }
1974
1975
1976 //------------------------------Value------------------------------------------
1977 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1978 const Type *t = klass_value_common(phase);
1979 if (t == Type::TOP)
1980 return t;
1981
1982 return t->make_narrowoop();
1983 }
1984
1985 //------------------------------Identity---------------------------------------
1986 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
1987 // Also feed through the klass in Allocate(...klass...)._klass.
1988 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
1989 Node *x = klass_identity_common(phase);
1990
1991 const Type *t = phase->type( x );
1992 if( t == Type::TOP ) return x;
1993 if( t->isa_narrowoop()) return x;
1994
1995 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
1996 }
1997
1998 //------------------------------Value-----------------------------------------
1999 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2000 // Either input is TOP ==> the result is TOP
2001 const Type *t1 = phase->type( in(MemNode::Memory) );
2002 if( t1 == Type::TOP ) return Type::TOP;
2003 Node *adr = in(MemNode::Address);
2004 const Type *t2 = phase->type( adr );
2005 if( t2 == Type::TOP ) return Type::TOP;
2006 const TypePtr *tp = t2->is_ptr();
2007 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2008 const TypeAryPtr *tap = tp->isa_aryptr();
2009 if( !tap ) return _type;
2010 return tap->size();
2011 }
2012
2013 //-------------------------------Ideal---------------------------------------
2014 // Feed through the length in AllocateArray(...length...)._length.
2015 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2016 Node* p = MemNode::Ideal_common(phase, can_reshape);
2017 if (p) return (p == NodeSentinel) ? NULL : p;
2018
2019 // Take apart the address into an oop and and offset.
2020 // Return 'this' if we cannot.
2021 Node* adr = in(MemNode::Address);
2022 intptr_t offset = 0;
2023 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2024 if (base == NULL) return NULL;
2025 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2026 if (tary == NULL) return NULL;
2027
2028 // We can fetch the length directly through an AllocateArrayNode.
2029 // This works even if the length is not constant (clone or newArray).
2030 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2031 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2032 if (alloc != NULL) {
2033 Node* allocated_length = alloc->Ideal_length();
2034 Node* len = alloc->make_ideal_length(tary, phase);
2035 if (allocated_length != len) {
2036 // New CastII improves on this.
2037 return len;
2038 }
2039 }
2040 }
2041
2042 return NULL;
2043 }
2044
2045 //------------------------------Identity---------------------------------------
2046 // Feed through the length in AllocateArray(...length...)._length.
2047 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2048 Node* x = LoadINode::Identity(phase);
2049 if (x != this) return x;
2050
2051 // Take apart the address into an oop and and offset.
2052 // Return 'this' if we cannot.
2053 Node* adr = in(MemNode::Address);
2054 intptr_t offset = 0;
2055 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2056 if (base == NULL) return this;
2057 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2058 if (tary == NULL) return this;
2059
2060 // We can fetch the length directly through an AllocateArrayNode.
2061 // This works even if the length is not constant (clone or newArray).
2062 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2063 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2064 if (alloc != NULL) {
2065 Node* allocated_length = alloc->Ideal_length();
2066 // Do not allow make_ideal_length to allocate a CastII node.
2067 Node* len = alloc->make_ideal_length(tary, phase, false);
2068 if (allocated_length == len) {
2069 // Return allocated_length only if it would not be improved by a CastII.
2070 return allocated_length;
2071 }
2072 }
2073 }
2074
2075 return this;
2076
2077 }
2078
2079 //=============================================================================
2080 //---------------------------StoreNode::make-----------------------------------
2081 // Polymorphic factory method:
2082 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2083 Compile* C = gvn.C;
2084 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2085 ctl != NULL, "raw memory operations should have control edge");
2086
2087 switch (bt) {
2088 case T_BOOLEAN:
2089 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2090 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2091 case T_CHAR:
2092 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2093 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2094 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2095 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2096 case T_ADDRESS:
2097 case T_OBJECT:
2098 #ifdef _LP64
2099 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2100 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2101 adr->bottom_type()->isa_rawptr())) {
2102 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2103 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2104 } else
2105 #endif
2106 {
2107 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2108 }
2109 }
2110 ShouldNotReachHere();
2111 return (StoreNode*)NULL;
2112 }
2113
2114 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2115 bool require_atomic = true;
2116 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2117 }
2118
2119
2120 //--------------------------bottom_type----------------------------------------
2121 const Type *StoreNode::bottom_type() const {
2122 return Type::MEMORY;
2123 }
2124
2125 //------------------------------hash-------------------------------------------
2126 uint StoreNode::hash() const {
2127 // unroll addition of interesting fields
2128 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2129
2130 // Since they are not commoned, do not hash them:
2131 return NO_HASH;
2132 }
2133
2134 //------------------------------Ideal------------------------------------------
2135 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2136 // When a store immediately follows a relevant allocation/initialization,
2137 // try to capture it into the initialization, or hoist it above.
2138 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2139 Node* p = MemNode::Ideal_common(phase, can_reshape);
2140 if (p) return (p == NodeSentinel) ? NULL : p;
2141
2142 Node* mem = in(MemNode::Memory);
2143 Node* address = in(MemNode::Address);
2144
2145 // Back-to-back stores to same address? Fold em up.
2146 // Generally unsafe if I have intervening uses...
2147 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
2148 // Looking at a dead closed cycle of memory?
2149 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2150
2151 assert(Opcode() == mem->Opcode() ||
2152 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2153 "no mismatched stores, except on raw memory");
2154
2155 if (mem->outcnt() == 1 && // check for intervening uses
2156 mem->as_Store()->memory_size() <= this->memory_size()) {
2157 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2158 // For example, 'mem' might be the final state at a conditional return.
2159 // Or, 'mem' might be used by some node which is live at the same time
2160 // 'this' is live, which might be unschedulable. So, require exactly
2161 // ONE user, the 'this' store, until such time as we clone 'mem' for
2162 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2163 if (can_reshape) { // (%%% is this an anachronism?)
2164 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2165 phase->is_IterGVN());
2166 } else {
2167 // It's OK to do this in the parser, since DU info is always accurate,
2168 // and the parser always refers to nodes via SafePointNode maps.
2169 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2170 }
2171 return this;
2172 }
2173 }
2174
2175 // Capture an unaliased, unconditional, simple store into an initializer.
2176 // Or, if it is independent of the allocation, hoist it above the allocation.
2177 if (ReduceFieldZeroing && /*can_reshape &&*/
2178 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2179 InitializeNode* init = mem->in(0)->as_Initialize();
2180 intptr_t offset = init->can_capture_store(this, phase);
2181 if (offset > 0) {
2182 Node* moved = init->capture_store(this, offset, phase);
2183 // If the InitializeNode captured me, it made a raw copy of me,
2184 // and I need to disappear.
2185 if (moved != NULL) {
2186 // %%% hack to ensure that Ideal returns a new node:
2187 mem = MergeMemNode::make(phase->C, mem);
2188 return mem; // fold me away
2189 }
2190 }
2191 }
2192
2193 return NULL; // No further progress
2194 }
2195
2196 //------------------------------Value-----------------------------------------
2197 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2198 // Either input is TOP ==> the result is TOP
2199 const Type *t1 = phase->type( in(MemNode::Memory) );
2200 if( t1 == Type::TOP ) return Type::TOP;
2201 const Type *t2 = phase->type( in(MemNode::Address) );
2202 if( t2 == Type::TOP ) return Type::TOP;
2203 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2204 if( t3 == Type::TOP ) return Type::TOP;
2205 return Type::MEMORY;
2206 }
2207
2208 //------------------------------Identity---------------------------------------
2209 // Remove redundant stores:
2210 // Store(m, p, Load(m, p)) changes to m.
2211 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2212 Node *StoreNode::Identity( PhaseTransform *phase ) {
2213 Node* mem = in(MemNode::Memory);
2214 Node* adr = in(MemNode::Address);
2215 Node* val = in(MemNode::ValueIn);
2216
2217 // Load then Store? Then the Store is useless
2218 if (val->is_Load() &&
2219 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2220 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2221 val->as_Load()->store_Opcode() == Opcode()) {
2222 return mem;
2223 }
2224
2225 // Two stores in a row of the same value?
2226 if (mem->is_Store() &&
2227 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2228 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2229 mem->Opcode() == Opcode()) {
2230 return mem;
2231 }
2232
2233 // Store of zero anywhere into a freshly-allocated object?
2234 // Then the store is useless.
2235 // (It must already have been captured by the InitializeNode.)
2236 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2237 // a newly allocated object is already all-zeroes everywhere
2238 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2239 return mem;
2240 }
2241
2242 // the store may also apply to zero-bits in an earlier object
2243 Node* prev_mem = find_previous_store(phase);
2244 // Steps (a), (b): Walk past independent stores to find an exact match.
2245 if (prev_mem != NULL) {
2246 Node* prev_val = can_see_stored_value(prev_mem, phase);
2247 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2248 // prev_val and val might differ by a cast; it would be good
2249 // to keep the more informative of the two.
2250 return mem;
2251 }
2252 }
2253 }
2254
2255 return this;
2256 }
2257
2258 //------------------------------match_edge-------------------------------------
2259 // Do we Match on this edge index or not? Match only memory & value
2260 uint StoreNode::match_edge(uint idx) const {
2261 return idx == MemNode::Address || idx == MemNode::ValueIn;
2262 }
2263
2264 //------------------------------cmp--------------------------------------------
2265 // Do not common stores up together. They generally have to be split
2266 // back up anyways, so do not bother.
2267 uint StoreNode::cmp( const Node &n ) const {
2268 return (&n == this); // Always fail except on self
2269 }
2270
2271 //------------------------------Ideal_masked_input-----------------------------
2272 // Check for a useless mask before a partial-word store
2273 // (StoreB ... (AndI valIn conIa) )
2274 // If (conIa & mask == mask) this simplifies to
2275 // (StoreB ... (valIn) )
2276 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2277 Node *val = in(MemNode::ValueIn);
2278 if( val->Opcode() == Op_AndI ) {
2279 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2280 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2281 set_req(MemNode::ValueIn, val->in(1));
2282 return this;
2283 }
2284 }
2285 return NULL;
2286 }
2287
2288
2289 //------------------------------Ideal_sign_extended_input----------------------
2290 // Check for useless sign-extension before a partial-word store
2291 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2292 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2293 // (StoreB ... (valIn) )
2294 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2295 Node *val = in(MemNode::ValueIn);
2296 if( val->Opcode() == Op_RShiftI ) {
2297 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2298 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2299 Node *shl = val->in(1);
2300 if( shl->Opcode() == Op_LShiftI ) {
2301 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2302 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2303 set_req(MemNode::ValueIn, shl->in(1));
2304 return this;
2305 }
2306 }
2307 }
2308 }
2309 return NULL;
2310 }
2311
2312 //------------------------------value_never_loaded-----------------------------------
2313 // Determine whether there are any possible loads of the value stored.
2314 // For simplicity, we actually check if there are any loads from the
2315 // address stored to, not just for loads of the value stored by this node.
2316 //
2317 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2318 Node *adr = in(Address);
2319 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2320 if (adr_oop == NULL)
2321 return false;
2322 if (!adr_oop->is_known_instance_field())
2323 return false; // if not a distinct instance, there may be aliases of the address
2324 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2325 Node *use = adr->fast_out(i);
2326 int opc = use->Opcode();
2327 if (use->is_Load() || use->is_LoadStore()) {
2328 return false;
2329 }
2330 }
2331 return true;
2332 }
2333
2334 //=============================================================================
2335 //------------------------------Ideal------------------------------------------
2336 // If the store is from an AND mask that leaves the low bits untouched, then
2337 // we can skip the AND operation. If the store is from a sign-extension
2338 // (a left shift, then right shift) we can skip both.
2339 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2340 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2341 if( progress != NULL ) return progress;
2342
2343 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2344 if( progress != NULL ) return progress;
2345
2346 // Finally check the default case
2347 return StoreNode::Ideal(phase, can_reshape);
2348 }
2349
2350 //=============================================================================
2351 //------------------------------Ideal------------------------------------------
2352 // If the store is from an AND mask that leaves the low bits untouched, then
2353 // we can skip the AND operation
2354 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2355 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2356 if( progress != NULL ) return progress;
2357
2358 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2359 if( progress != NULL ) return progress;
2360
2361 // Finally check the default case
2362 return StoreNode::Ideal(phase, can_reshape);
2363 }
2364
2365 //=============================================================================
2366 //------------------------------Identity---------------------------------------
2367 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2368 // No need to card mark when storing a null ptr
2369 Node* my_store = in(MemNode::OopStore);
2370 if (my_store->is_Store()) {
2371 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2372 if( t1 == TypePtr::NULL_PTR ) {
2373 return in(MemNode::Memory);
2374 }
2375 }
2376 return this;
2377 }
2378
2379 //=============================================================================
2380 //------------------------------Ideal---------------------------------------
2381 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2382 Node* progress = StoreNode::Ideal(phase, can_reshape);
2383 if (progress != NULL) return progress;
2384
2385 Node* my_store = in(MemNode::OopStore);
2386 if (my_store->is_MergeMem()) {
2387 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2388 set_req(MemNode::OopStore, mem);
2389 return this;
2390 }
2391
2392 return NULL;
2393 }
2394
2395 //------------------------------Value-----------------------------------------
2396 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2397 // Either input is TOP ==> the result is TOP
2398 const Type *t = phase->type( in(MemNode::Memory) );
2399 if( t == Type::TOP ) return Type::TOP;
2400 t = phase->type( in(MemNode::Address) );
2401 if( t == Type::TOP ) return Type::TOP;
2402 t = phase->type( in(MemNode::ValueIn) );
2403 if( t == Type::TOP ) return Type::TOP;
2404 // If extra input is TOP ==> the result is TOP
2405 t = phase->type( in(MemNode::OopStore) );
2406 if( t == Type::TOP ) return Type::TOP;
2407
2408 return StoreNode::Value( phase );
2409 }
2410
2411
2412 //=============================================================================
2413 //----------------------------------SCMemProjNode------------------------------
2414 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2415 {
2416 return bottom_type();
2417 }
2418
2419 //=============================================================================
2420 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2421 init_req(MemNode::Control, c );
2422 init_req(MemNode::Memory , mem);
2423 init_req(MemNode::Address, adr);
2424 init_req(MemNode::ValueIn, val);
2425 init_req( ExpectedIn, ex );
2426 init_class_id(Class_LoadStore);
2427
2428 }
2429
2430 //=============================================================================
2431 //-------------------------------adr_type--------------------------------------
2432 // Do we Match on this edge index or not? Do not match memory
2433 const TypePtr* ClearArrayNode::adr_type() const {
2434 Node *adr = in(3);
2435 return MemNode::calculate_adr_type(adr->bottom_type());
2436 }
2437
2438 //------------------------------match_edge-------------------------------------
2439 // Do we Match on this edge index or not? Do not match memory
2440 uint ClearArrayNode::match_edge(uint idx) const {
2441 return idx > 1;
2442 }
2443
2444 //------------------------------Identity---------------------------------------
2445 // Clearing a zero length array does nothing
2446 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2447 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2448 }
2449
2450 //------------------------------Idealize---------------------------------------
2451 // Clearing a short array is faster with stores
2452 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2453 const int unit = BytesPerLong;
2454 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2455 if (!t) return NULL;
2456 if (!t->is_con()) return NULL;
2457 intptr_t raw_count = t->get_con();
2458 intptr_t size = raw_count;
2459 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2460 // Clearing nothing uses the Identity call.
2461 // Negative clears are possible on dead ClearArrays
2462 // (see jck test stmt114.stmt11402.val).
2463 if (size <= 0 || size % unit != 0) return NULL;
2464 intptr_t count = size / unit;
2465 // Length too long; use fast hardware clear
2466 if (size > Matcher::init_array_short_size) return NULL;
2467 Node *mem = in(1);
2468 if( phase->type(mem)==Type::TOP ) return NULL;
2469 Node *adr = in(3);
2470 const Type* at = phase->type(adr);
2471 if( at==Type::TOP ) return NULL;
2472 const TypePtr* atp = at->isa_ptr();
2473 // adjust atp to be the correct array element address type
2474 if (atp == NULL) atp = TypePtr::BOTTOM;
2475 else atp = atp->add_offset(Type::OffsetBot);
2476 // Get base for derived pointer purposes
2477 if( adr->Opcode() != Op_AddP ) Unimplemented();
2478 Node *base = adr->in(1);
2479
2480 Node *zero = phase->makecon(TypeLong::ZERO);
2481 Node *off = phase->MakeConX(BytesPerLong);
2482 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2483 count--;
2484 while( count-- ) {
2485 mem = phase->transform(mem);
2486 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2487 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2488 }
2489 return mem;
2490 }
2491
2492 //----------------------------step_through----------------------------------
2493 // Return allocation input memory edge if it is different instance
2494 // or itself if it is the one we are looking for.
2495 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2496 Node* n = *np;
2497 assert(n->is_ClearArray(), "sanity");
2498 intptr_t offset;
2499 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2500 // This method is called only before Allocate nodes are expanded during
2501 // macro nodes expansion. Before that ClearArray nodes are only generated
2502 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2503 assert(alloc != NULL, "should have allocation");
2504 if (alloc->_idx == instance_id) {
2505 // Can not bypass initialization of the instance we are looking for.
2506 return false;
2507 }
2508 // Otherwise skip it.
2509 InitializeNode* init = alloc->initialization();
2510 if (init != NULL)
2511 *np = init->in(TypeFunc::Memory);
2512 else
2513 *np = alloc->in(TypeFunc::Memory);
2514 return true;
2515 }
2516
2517 //----------------------------clear_memory-------------------------------------
2518 // Generate code to initialize object storage to zero.
2519 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2520 intptr_t start_offset,
2521 Node* end_offset,
2522 PhaseGVN* phase) {
2523 Compile* C = phase->C;
2524 intptr_t offset = start_offset;
2525
2526 int unit = BytesPerLong;
2527 if ((offset % unit) != 0) {
2528 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2529 adr = phase->transform(adr);
2530 const TypePtr* atp = TypeRawPtr::BOTTOM;
2531 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2532 mem = phase->transform(mem);
2533 offset += BytesPerInt;
2534 }
2535 assert((offset % unit) == 0, "");
2536
2537 // Initialize the remaining stuff, if any, with a ClearArray.
2538 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2539 }
2540
2541 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2542 Node* start_offset,
2543 Node* end_offset,
2544 PhaseGVN* phase) {
2545 if (start_offset == end_offset) {
2546 // nothing to do
2547 return mem;
2548 }
2549
2550 Compile* C = phase->C;
2551 int unit = BytesPerLong;
2552 Node* zbase = start_offset;
2553 Node* zend = end_offset;
2554
2555 // Scale to the unit required by the CPU:
2556 if (!Matcher::init_array_count_is_in_bytes) {
2557 Node* shift = phase->intcon(exact_log2(unit));
2558 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2559 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2560 }
2561
2562 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2563 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2564
2565 // Bulk clear double-words
2566 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2567 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2568 return phase->transform(mem);
2569 }
2570
2571 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2572 intptr_t start_offset,
2573 intptr_t end_offset,
2574 PhaseGVN* phase) {
2575 if (start_offset == end_offset) {
2576 // nothing to do
2577 return mem;
2578 }
2579
2580 Compile* C = phase->C;
2581 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2582 intptr_t done_offset = end_offset;
2583 if ((done_offset % BytesPerLong) != 0) {
2584 done_offset -= BytesPerInt;
2585 }
2586 if (done_offset > start_offset) {
2587 mem = clear_memory(ctl, mem, dest,
2588 start_offset, phase->MakeConX(done_offset), phase);
2589 }
2590 if (done_offset < end_offset) { // emit the final 32-bit store
2591 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2592 adr = phase->transform(adr);
2593 const TypePtr* atp = TypeRawPtr::BOTTOM;
2594 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2595 mem = phase->transform(mem);
2596 done_offset += BytesPerInt;
2597 }
2598 assert(done_offset == end_offset, "");
2599 return mem;
2600 }
2601
2602 //=============================================================================
2603 // Do we match on this edge? No memory edges
2604 uint StrCompNode::match_edge(uint idx) const {
2605 return idx == 2 || idx == 3; // StrComp (Binary str1 cnt1) (Binary str2 cnt2)
2606 }
2607
2608 //------------------------------Ideal------------------------------------------
2609 // Return a node which is more "ideal" than the current node. Strip out
2610 // control copies
2611 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2612 return remove_dead_region(phase, can_reshape) ? this : NULL;
2613 }
2614
2615 //=============================================================================
2616 // Do we match on this edge? No memory edges
2617 uint StrEqualsNode::match_edge(uint idx) const {
2618 return idx == 2 || idx == 3; // StrEquals (Binary str1 str2) cnt
2619 }
2620
2621 //------------------------------Ideal------------------------------------------
2622 // Return a node which is more "ideal" than the current node. Strip out
2623 // control copies
2624 Node *StrEqualsNode::Ideal(PhaseGVN *phase, bool can_reshape){
2625 return remove_dead_region(phase, can_reshape) ? this : NULL;
2626 }
2627
2628 //=============================================================================
2629 // Do we match on this edge? No memory edges
2630 uint StrIndexOfNode::match_edge(uint idx) const {
2631 return idx == 2 || idx == 3; // StrIndexOf (Binary str1 cnt1) (Binary str2 cnt2)
2632 }
2633
2634 //------------------------------Ideal------------------------------------------
2635 // Return a node which is more "ideal" than the current node. Strip out
2636 // control copies
2637 Node *StrIndexOfNode::Ideal(PhaseGVN *phase, bool can_reshape){
2638 return remove_dead_region(phase, can_reshape) ? this : NULL;
2639 }
2640
2641 //=============================================================================
2642 // Do we match on this edge? No memory edges
2643 uint AryEqNode::match_edge(uint idx) const {
2644 return idx == 2 || idx == 3; // StrEquals ary1 ary2
2645 }
2646 //------------------------------Ideal------------------------------------------
2647 // Return a node which is more "ideal" than the current node. Strip out
2648 // control copies
2649 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2650 return remove_dead_region(phase, can_reshape) ? this : NULL;
2651 }
2652
2653 //=============================================================================
2654 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2655 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2656 _adr_type(C->get_adr_type(alias_idx))
2657 {
2658 init_class_id(Class_MemBar);
2659 Node* top = C->top();
2660 init_req(TypeFunc::I_O,top);
2661 init_req(TypeFunc::FramePtr,top);
2662 init_req(TypeFunc::ReturnAdr,top);
2663 if (precedent != NULL)
2664 init_req(TypeFunc::Parms, precedent);
2665 }
2666
2667 //------------------------------cmp--------------------------------------------
2668 uint MemBarNode::hash() const { return NO_HASH; }
2669 uint MemBarNode::cmp( const Node &n ) const {
2670 return (&n == this); // Always fail except on self
2671 }
2672
2673 //------------------------------make-------------------------------------------
2674 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2675 int len = Precedent + (pn == NULL? 0: 1);
2676 switch (opcode) {
2677 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2678 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2679 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2680 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2681 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2682 default: ShouldNotReachHere(); return NULL;
2683 }
2684 }
2685
2686 //------------------------------Ideal------------------------------------------
2687 // Return a node which is more "ideal" than the current node. Strip out
2688 // control copies
2689 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2690 if (remove_dead_region(phase, can_reshape)) return this;
2691
2692 // Eliminate volatile MemBars for scalar replaced objects.
2693 if (can_reshape && req() == (Precedent+1) &&
2694 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2695 // Volatile field loads and stores.
2696 Node* my_mem = in(MemBarNode::Precedent);
2697 if (my_mem != NULL && my_mem->is_Mem()) {
2698 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2699 // Check for scalar replaced object reference.
2700 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2701 t_oop->offset() != Type::OffsetBot &&
2702 t_oop->offset() != Type::OffsetTop) {
2703 // Replace MemBar projections by its inputs.
2704 PhaseIterGVN* igvn = phase->is_IterGVN();
2705 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2706 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2707 // Must return either the original node (now dead) or a new node
2708 // (Do not return a top here, since that would break the uniqueness of top.)
2709 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2710 }
2711 }
2712 }
2713 return NULL;
2714 }
2715
2716 //------------------------------Value------------------------------------------
2717 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2718 if( !in(0) ) return Type::TOP;
2719 if( phase->type(in(0)) == Type::TOP )
2720 return Type::TOP;
2721 return TypeTuple::MEMBAR;
2722 }
2723
2724 //------------------------------match------------------------------------------
2725 // Construct projections for memory.
2726 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2727 switch (proj->_con) {
2728 case TypeFunc::Control:
2729 case TypeFunc::Memory:
2730 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2731 }
2732 ShouldNotReachHere();
2733 return NULL;
2734 }
2735
2736 //===========================InitializeNode====================================
2737 // SUMMARY:
2738 // This node acts as a memory barrier on raw memory, after some raw stores.
2739 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2740 // The Initialize can 'capture' suitably constrained stores as raw inits.
2741 // It can coalesce related raw stores into larger units (called 'tiles').
2742 // It can avoid zeroing new storage for memory units which have raw inits.
2743 // At macro-expansion, it is marked 'complete', and does not optimize further.
2744 //
2745 // EXAMPLE:
2746 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2747 // ctl = incoming control; mem* = incoming memory
2748 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2749 // First allocate uninitialized memory and fill in the header:
2750 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2751 // ctl := alloc.Control; mem* := alloc.Memory*
2752 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2753 // Then initialize to zero the non-header parts of the raw memory block:
2754 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2755 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2756 // After the initialize node executes, the object is ready for service:
2757 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2758 // Suppose its body is immediately initialized as {1,2}:
2759 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2760 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2761 // mem.SLICE(#short[*]) := store2
2762 //
2763 // DETAILS:
2764 // An InitializeNode collects and isolates object initialization after
2765 // an AllocateNode and before the next possible safepoint. As a
2766 // memory barrier (MemBarNode), it keeps critical stores from drifting
2767 // down past any safepoint or any publication of the allocation.
2768 // Before this barrier, a newly-allocated object may have uninitialized bits.
2769 // After this barrier, it may be treated as a real oop, and GC is allowed.
2770 //
2771 // The semantics of the InitializeNode include an implicit zeroing of
2772 // the new object from object header to the end of the object.
2773 // (The object header and end are determined by the AllocateNode.)
2774 //
2775 // Certain stores may be added as direct inputs to the InitializeNode.
2776 // These stores must update raw memory, and they must be to addresses
2777 // derived from the raw address produced by AllocateNode, and with
2778 // a constant offset. They must be ordered by increasing offset.
2779 // The first one is at in(RawStores), the last at in(req()-1).
2780 // Unlike most memory operations, they are not linked in a chain,
2781 // but are displayed in parallel as users of the rawmem output of
2782 // the allocation.
2783 //
2784 // (See comments in InitializeNode::capture_store, which continue
2785 // the example given above.)
2786 //
2787 // When the associated Allocate is macro-expanded, the InitializeNode
2788 // may be rewritten to optimize collected stores. A ClearArrayNode
2789 // may also be created at that point to represent any required zeroing.
2790 // The InitializeNode is then marked 'complete', prohibiting further
2791 // capturing of nearby memory operations.
2792 //
2793 // During macro-expansion, all captured initializations which store
2794 // constant values of 32 bits or smaller are coalesced (if advantageous)
2795 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2796 // initialized in fewer memory operations. Memory words which are
2797 // covered by neither tiles nor non-constant stores are pre-zeroed
2798 // by explicit stores of zero. (The code shape happens to do all
2799 // zeroing first, then all other stores, with both sequences occurring
2800 // in order of ascending offsets.)
2801 //
2802 // Alternatively, code may be inserted between an AllocateNode and its
2803 // InitializeNode, to perform arbitrary initialization of the new object.
2804 // E.g., the object copying intrinsics insert complex data transfers here.
2805 // The initialization must then be marked as 'complete' disable the
2806 // built-in zeroing semantics and the collection of initializing stores.
2807 //
2808 // While an InitializeNode is incomplete, reads from the memory state
2809 // produced by it are optimizable if they match the control edge and
2810 // new oop address associated with the allocation/initialization.
2811 // They return a stored value (if the offset matches) or else zero.
2812 // A write to the memory state, if it matches control and address,
2813 // and if it is to a constant offset, may be 'captured' by the
2814 // InitializeNode. It is cloned as a raw memory operation and rewired
2815 // inside the initialization, to the raw oop produced by the allocation.
2816 // Operations on addresses which are provably distinct (e.g., to
2817 // other AllocateNodes) are allowed to bypass the initialization.
2818 //
2819 // The effect of all this is to consolidate object initialization
2820 // (both arrays and non-arrays, both piecewise and bulk) into a
2821 // single location, where it can be optimized as a unit.
2822 //
2823 // Only stores with an offset less than TrackedInitializationLimit words
2824 // will be considered for capture by an InitializeNode. This puts a
2825 // reasonable limit on the complexity of optimized initializations.
2826
2827 //---------------------------InitializeNode------------------------------------
2828 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2829 : _is_complete(false),
2830 MemBarNode(C, adr_type, rawoop)
2831 {
2832 init_class_id(Class_Initialize);
2833
2834 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2835 assert(in(RawAddress) == rawoop, "proper init");
2836 // Note: allocation() can be NULL, for secondary initialization barriers
2837 }
2838
2839 // Since this node is not matched, it will be processed by the
2840 // register allocator. Declare that there are no constraints
2841 // on the allocation of the RawAddress edge.
2842 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2843 // This edge should be set to top, by the set_complete. But be conservative.
2844 if (idx == InitializeNode::RawAddress)
2845 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2846 return RegMask::Empty;
2847 }
2848
2849 Node* InitializeNode::memory(uint alias_idx) {
2850 Node* mem = in(Memory);
2851 if (mem->is_MergeMem()) {
2852 return mem->as_MergeMem()->memory_at(alias_idx);
2853 } else {
2854 // incoming raw memory is not split
2855 return mem;
2856 }
2857 }
2858
2859 bool InitializeNode::is_non_zero() {
2860 if (is_complete()) return false;
2861 remove_extra_zeroes();
2862 return (req() > RawStores);
2863 }
2864
2865 void InitializeNode::set_complete(PhaseGVN* phase) {
2866 assert(!is_complete(), "caller responsibility");
2867 _is_complete = true;
2868
2869 // After this node is complete, it contains a bunch of
2870 // raw-memory initializations. There is no need for
2871 // it to have anything to do with non-raw memory effects.
2872 // Therefore, tell all non-raw users to re-optimize themselves,
2873 // after skipping the memory effects of this initialization.
2874 PhaseIterGVN* igvn = phase->is_IterGVN();
2875 if (igvn) igvn->add_users_to_worklist(this);
2876 }
2877
2878 // convenience function
2879 // return false if the init contains any stores already
2880 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2881 InitializeNode* init = initialization();
2882 if (init == NULL || init->is_complete()) return false;
2883 init->remove_extra_zeroes();
2884 // for now, if this allocation has already collected any inits, bail:
2885 if (init->is_non_zero()) return false;
2886 init->set_complete(phase);
2887 return true;
2888 }
2889
2890 void InitializeNode::remove_extra_zeroes() {
2891 if (req() == RawStores) return;
2892 Node* zmem = zero_memory();
2893 uint fill = RawStores;
2894 for (uint i = fill; i < req(); i++) {
2895 Node* n = in(i);
2896 if (n->is_top() || n == zmem) continue; // skip
2897 if (fill < i) set_req(fill, n); // compact
2898 ++fill;
2899 }
2900 // delete any empty spaces created:
2901 while (fill < req()) {
2902 del_req(fill);
2903 }
2904 }
2905
2906 // Helper for remembering which stores go with which offsets.
2907 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2908 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2909 intptr_t offset = -1;
2910 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2911 phase, offset);
2912 if (base == NULL) return -1; // something is dead,
2913 if (offset < 0) return -1; // dead, dead
2914 return offset;
2915 }
2916
2917 // Helper for proving that an initialization expression is
2918 // "simple enough" to be folded into an object initialization.
2919 // Attempts to prove that a store's initial value 'n' can be captured
2920 // within the initialization without creating a vicious cycle, such as:
2921 // { Foo p = new Foo(); p.next = p; }
2922 // True for constants and parameters and small combinations thereof.
2923 bool InitializeNode::detect_init_independence(Node* n,
2924 bool st_is_pinned,
2925 int& count) {
2926 if (n == NULL) return true; // (can this really happen?)
2927 if (n->is_Proj()) n = n->in(0);
2928 if (n == this) return false; // found a cycle
2929 if (n->is_Con()) return true;
2930 if (n->is_Start()) return true; // params, etc., are OK
2931 if (n->is_Root()) return true; // even better
2932
2933 Node* ctl = n->in(0);
2934 if (ctl != NULL && !ctl->is_top()) {
2935 if (ctl->is_Proj()) ctl = ctl->in(0);
2936 if (ctl == this) return false;
2937
2938 // If we already know that the enclosing memory op is pinned right after
2939 // the init, then any control flow that the store has picked up
2940 // must have preceded the init, or else be equal to the init.
2941 // Even after loop optimizations (which might change control edges)
2942 // a store is never pinned *before* the availability of its inputs.
2943 if (!MemNode::all_controls_dominate(n, this))
2944 return false; // failed to prove a good control
2945
2946 }
2947
2948 // Check data edges for possible dependencies on 'this'.
2949 if ((count += 1) > 20) return false; // complexity limit
2950 for (uint i = 1; i < n->req(); i++) {
2951 Node* m = n->in(i);
2952 if (m == NULL || m == n || m->is_top()) continue;
2953 uint first_i = n->find_edge(m);
2954 if (i != first_i) continue; // process duplicate edge just once
2955 if (!detect_init_independence(m, st_is_pinned, count)) {
2956 return false;
2957 }
2958 }
2959
2960 return true;
2961 }
2962
2963 // Here are all the checks a Store must pass before it can be moved into
2964 // an initialization. Returns zero if a check fails.
2965 // On success, returns the (constant) offset to which the store applies,
2966 // within the initialized memory.
2967 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2968 const int FAIL = 0;
2969 if (st->req() != MemNode::ValueIn + 1)
2970 return FAIL; // an inscrutable StoreNode (card mark?)
2971 Node* ctl = st->in(MemNode::Control);
2972 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2973 return FAIL; // must be unconditional after the initialization
2974 Node* mem = st->in(MemNode::Memory);
2975 if (!(mem->is_Proj() && mem->in(0) == this))
2976 return FAIL; // must not be preceded by other stores
2977 Node* adr = st->in(MemNode::Address);
2978 intptr_t offset;
2979 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2980 if (alloc == NULL)
2981 return FAIL; // inscrutable address
2982 if (alloc != allocation())
2983 return FAIL; // wrong allocation! (store needs to float up)
2984 Node* val = st->in(MemNode::ValueIn);
2985 int complexity_count = 0;
2986 if (!detect_init_independence(val, true, complexity_count))
2987 return FAIL; // stored value must be 'simple enough'
2988
2989 return offset; // success
2990 }
2991
2992 // Find the captured store in(i) which corresponds to the range
2993 // [start..start+size) in the initialized object.
2994 // If there is one, return its index i. If there isn't, return the
2995 // negative of the index where it should be inserted.
2996 // Return 0 if the queried range overlaps an initialization boundary
2997 // or if dead code is encountered.
2998 // If size_in_bytes is zero, do not bother with overlap checks.
2999 int InitializeNode::captured_store_insertion_point(intptr_t start,
3000 int size_in_bytes,
3001 PhaseTransform* phase) {
3002 const int FAIL = 0, MAX_STORE = BytesPerLong;
3003
3004 if (is_complete())
3005 return FAIL; // arraycopy got here first; punt
3006
3007 assert(allocation() != NULL, "must be present");
3008
3009 // no negatives, no header fields:
3010 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3011
3012 // after a certain size, we bail out on tracking all the stores:
3013 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3014 if (start >= ti_limit) return FAIL;
3015
3016 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3017 if (i >= limit) return -(int)i; // not found; here is where to put it
3018
3019 Node* st = in(i);
3020 intptr_t st_off = get_store_offset(st, phase);
3021 if (st_off < 0) {
3022 if (st != zero_memory()) {
3023 return FAIL; // bail out if there is dead garbage
3024 }
3025 } else if (st_off > start) {
3026 // ...we are done, since stores are ordered
3027 if (st_off < start + size_in_bytes) {
3028 return FAIL; // the next store overlaps
3029 }
3030 return -(int)i; // not found; here is where to put it
3031 } else if (st_off < start) {
3032 if (size_in_bytes != 0 &&
3033 start < st_off + MAX_STORE &&
3034 start < st_off + st->as_Store()->memory_size()) {
3035 return FAIL; // the previous store overlaps
3036 }
3037 } else {
3038 if (size_in_bytes != 0 &&
3039 st->as_Store()->memory_size() != size_in_bytes) {
3040 return FAIL; // mismatched store size
3041 }
3042 return i;
3043 }
3044
3045 ++i;
3046 }
3047 }
3048
3049 // Look for a captured store which initializes at the offset 'start'
3050 // with the given size. If there is no such store, and no other
3051 // initialization interferes, then return zero_memory (the memory
3052 // projection of the AllocateNode).
3053 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3054 PhaseTransform* phase) {
3055 assert(stores_are_sane(phase), "");
3056 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3057 if (i == 0) {
3058 return NULL; // something is dead
3059 } else if (i < 0) {
3060 return zero_memory(); // just primordial zero bits here
3061 } else {
3062 Node* st = in(i); // here is the store at this position
3063 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3064 return st;
3065 }
3066 }
3067
3068 // Create, as a raw pointer, an address within my new object at 'offset'.
3069 Node* InitializeNode::make_raw_address(intptr_t offset,
3070 PhaseTransform* phase) {
3071 Node* addr = in(RawAddress);
3072 if (offset != 0) {
3073 Compile* C = phase->C;
3074 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3075 phase->MakeConX(offset)) );
3076 }
3077 return addr;
3078 }
3079
3080 // Clone the given store, converting it into a raw store
3081 // initializing a field or element of my new object.
3082 // Caller is responsible for retiring the original store,
3083 // with subsume_node or the like.
3084 //
3085 // From the example above InitializeNode::InitializeNode,
3086 // here are the old stores to be captured:
3087 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3088 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3089 //
3090 // Here is the changed code; note the extra edges on init:
3091 // alloc = (Allocate ...)
3092 // rawoop = alloc.RawAddress
3093 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3094 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3095 // init = (Initialize alloc.Control alloc.Memory rawoop
3096 // rawstore1 rawstore2)
3097 //
3098 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3099 PhaseTransform* phase) {
3100 assert(stores_are_sane(phase), "");
3101
3102 if (start < 0) return NULL;
3103 assert(can_capture_store(st, phase) == start, "sanity");
3104
3105 Compile* C = phase->C;
3106 int size_in_bytes = st->memory_size();
3107 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3108 if (i == 0) return NULL; // bail out
3109 Node* prev_mem = NULL; // raw memory for the captured store
3110 if (i > 0) {
3111 prev_mem = in(i); // there is a pre-existing store under this one
3112 set_req(i, C->top()); // temporarily disconnect it
3113 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3114 } else {
3115 i = -i; // no pre-existing store
3116 prev_mem = zero_memory(); // a slice of the newly allocated object
3117 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3118 set_req(--i, C->top()); // reuse this edge; it has been folded away
3119 else
3120 ins_req(i, C->top()); // build a new edge
3121 }
3122 Node* new_st = st->clone();
3123 new_st->set_req(MemNode::Control, in(Control));
3124 new_st->set_req(MemNode::Memory, prev_mem);
3125 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3126 new_st = phase->transform(new_st);
3127
3128 // At this point, new_st might have swallowed a pre-existing store
3129 // at the same offset, or perhaps new_st might have disappeared,
3130 // if it redundantly stored the same value (or zero to fresh memory).
3131
3132 // In any case, wire it in:
3133 set_req(i, new_st);
3134
3135 // The caller may now kill the old guy.
3136 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3137 assert(check_st == new_st || check_st == NULL, "must be findable");
3138 assert(!is_complete(), "");
3139 return new_st;
3140 }
3141
3142 static bool store_constant(jlong* tiles, int num_tiles,
3143 intptr_t st_off, int st_size,
3144 jlong con) {
3145 if ((st_off & (st_size-1)) != 0)
3146 return false; // strange store offset (assume size==2**N)
3147 address addr = (address)tiles + st_off;
3148 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3149 switch (st_size) {
3150 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3151 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3152 case sizeof(jint): *(jint*) addr = (jint) con; break;
3153 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3154 default: return false; // strange store size (detect size!=2**N here)
3155 }
3156 return true; // return success to caller
3157 }
3158
3159 // Coalesce subword constants into int constants and possibly
3160 // into long constants. The goal, if the CPU permits,
3161 // is to initialize the object with a small number of 64-bit tiles.
3162 // Also, convert floating-point constants to bit patterns.
3163 // Non-constants are not relevant to this pass.
3164 //
3165 // In terms of the running example on InitializeNode::InitializeNode
3166 // and InitializeNode::capture_store, here is the transformation
3167 // of rawstore1 and rawstore2 into rawstore12:
3168 // alloc = (Allocate ...)
3169 // rawoop = alloc.RawAddress
3170 // tile12 = 0x00010002
3171 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3172 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3173 //
3174 void
3175 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3176 Node* size_in_bytes,
3177 PhaseGVN* phase) {
3178 Compile* C = phase->C;
3179
3180 assert(stores_are_sane(phase), "");
3181 // Note: After this pass, they are not completely sane,
3182 // since there may be some overlaps.
3183
3184 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3185
3186 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3187 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3188 size_limit = MIN2(size_limit, ti_limit);
3189 size_limit = align_size_up(size_limit, BytesPerLong);
3190 int num_tiles = size_limit / BytesPerLong;
3191
3192 // allocate space for the tile map:
3193 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3194 jlong tiles_buf[small_len];
3195 Node* nodes_buf[small_len];
3196 jlong inits_buf[small_len];
3197 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3198 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3199 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3200 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3201 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3202 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3203 // tiles: exact bitwise model of all primitive constants
3204 // nodes: last constant-storing node subsumed into the tiles model
3205 // inits: which bytes (in each tile) are touched by any initializations
3206
3207 //// Pass A: Fill in the tile model with any relevant stores.
3208
3209 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3210 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3211 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3212 Node* zmem = zero_memory(); // initially zero memory state
3213 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3214 Node* st = in(i);
3215 intptr_t st_off = get_store_offset(st, phase);
3216
3217 // Figure out the store's offset and constant value:
3218 if (st_off < header_size) continue; //skip (ignore header)
3219 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3220 int st_size = st->as_Store()->memory_size();
3221 if (st_off + st_size > size_limit) break;
3222
3223 // Record which bytes are touched, whether by constant or not.
3224 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3225 continue; // skip (strange store size)
3226
3227 const Type* val = phase->type(st->in(MemNode::ValueIn));
3228 if (!val->singleton()) continue; //skip (non-con store)
3229 BasicType type = val->basic_type();
3230
3231 jlong con = 0;
3232 switch (type) {
3233 case T_INT: con = val->is_int()->get_con(); break;
3234 case T_LONG: con = val->is_long()->get_con(); break;
3235 case T_FLOAT: con = jint_cast(val->getf()); break;
3236 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3237 default: continue; //skip (odd store type)
3238 }
3239
3240 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3241 st->Opcode() == Op_StoreL) {
3242 continue; // This StoreL is already optimal.
3243 }
3244
3245 // Store down the constant.
3246 store_constant(tiles, num_tiles, st_off, st_size, con);
3247
3248 intptr_t j = st_off >> LogBytesPerLong;
3249
3250 if (type == T_INT && st_size == BytesPerInt
3251 && (st_off & BytesPerInt) == BytesPerInt) {
3252 jlong lcon = tiles[j];
3253 if (!Matcher::isSimpleConstant64(lcon) &&
3254 st->Opcode() == Op_StoreI) {
3255 // This StoreI is already optimal by itself.
3256 jint* intcon = (jint*) &tiles[j];
3257 intcon[1] = 0; // undo the store_constant()
3258
3259 // If the previous store is also optimal by itself, back up and
3260 // undo the action of the previous loop iteration... if we can.
3261 // But if we can't, just let the previous half take care of itself.
3262 st = nodes[j];
3263 st_off -= BytesPerInt;
3264 con = intcon[0];
3265 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3266 assert(st_off >= header_size, "still ignoring header");
3267 assert(get_store_offset(st, phase) == st_off, "must be");
3268 assert(in(i-1) == zmem, "must be");
3269 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3270 assert(con == tcon->is_int()->get_con(), "must be");
3271 // Undo the effects of the previous loop trip, which swallowed st:
3272 intcon[0] = 0; // undo store_constant()
3273 set_req(i-1, st); // undo set_req(i, zmem)
3274 nodes[j] = NULL; // undo nodes[j] = st
3275 --old_subword; // undo ++old_subword
3276 }
3277 continue; // This StoreI is already optimal.
3278 }
3279 }
3280
3281 // This store is not needed.
3282 set_req(i, zmem);
3283 nodes[j] = st; // record for the moment
3284 if (st_size < BytesPerLong) // something has changed
3285 ++old_subword; // includes int/float, but who's counting...
3286 else ++old_long;
3287 }
3288
3289 if ((old_subword + old_long) == 0)
3290 return; // nothing more to do
3291
3292 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3293 // Be sure to insert them before overlapping non-constant stores.
3294 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3295 for (int j = 0; j < num_tiles; j++) {
3296 jlong con = tiles[j];
3297 jlong init = inits[j];
3298 if (con == 0) continue;
3299 jint con0, con1; // split the constant, address-wise
3300 jint init0, init1; // split the init map, address-wise
3301 { union { jlong con; jint intcon[2]; } u;
3302 u.con = con;
3303 con0 = u.intcon[0];
3304 con1 = u.intcon[1];
3305 u.con = init;
3306 init0 = u.intcon[0];
3307 init1 = u.intcon[1];
3308 }
3309
3310 Node* old = nodes[j];
3311 assert(old != NULL, "need the prior store");
3312 intptr_t offset = (j * BytesPerLong);
3313
3314 bool split = !Matcher::isSimpleConstant64(con);
3315
3316 if (offset < header_size) {
3317 assert(offset + BytesPerInt >= header_size, "second int counts");
3318 assert(*(jint*)&tiles[j] == 0, "junk in header");
3319 split = true; // only the second word counts
3320 // Example: int a[] = { 42 ... }
3321 } else if (con0 == 0 && init0 == -1) {
3322 split = true; // first word is covered by full inits
3323 // Example: int a[] = { ... foo(), 42 ... }
3324 } else if (con1 == 0 && init1 == -1) {
3325 split = true; // second word is covered by full inits
3326 // Example: int a[] = { ... 42, foo() ... }
3327 }
3328
3329 // Here's a case where init0 is neither 0 nor -1:
3330 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3331 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3332 // In this case the tile is not split; it is (jlong)42.
3333 // The big tile is stored down, and then the foo() value is inserted.
3334 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3335
3336 Node* ctl = old->in(MemNode::Control);
3337 Node* adr = make_raw_address(offset, phase);
3338 const TypePtr* atp = TypeRawPtr::BOTTOM;
3339
3340 // One or two coalesced stores to plop down.
3341 Node* st[2];
3342 intptr_t off[2];
3343 int nst = 0;
3344 if (!split) {
3345 ++new_long;
3346 off[nst] = offset;
3347 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3348 phase->longcon(con), T_LONG);
3349 } else {
3350 // Omit either if it is a zero.
3351 if (con0 != 0) {
3352 ++new_int;
3353 off[nst] = offset;
3354 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3355 phase->intcon(con0), T_INT);
3356 }
3357 if (con1 != 0) {
3358 ++new_int;
3359 offset += BytesPerInt;
3360 adr = make_raw_address(offset, phase);
3361 off[nst] = offset;
3362 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3363 phase->intcon(con1), T_INT);
3364 }
3365 }
3366
3367 // Insert second store first, then the first before the second.
3368 // Insert each one just before any overlapping non-constant stores.
3369 while (nst > 0) {
3370 Node* st1 = st[--nst];
3371 C->copy_node_notes_to(st1, old);
3372 st1 = phase->transform(st1);
3373 offset = off[nst];
3374 assert(offset >= header_size, "do not smash header");
3375 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3376 guarantee(ins_idx != 0, "must re-insert constant store");
3377 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3378 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3379 set_req(--ins_idx, st1);
3380 else
3381 ins_req(ins_idx, st1);
3382 }
3383 }
3384
3385 if (PrintCompilation && WizardMode)
3386 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3387 old_subword, old_long, new_int, new_long);
3388 if (C->log() != NULL)
3389 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3390 old_subword, old_long, new_int, new_long);
3391
3392 // Clean up any remaining occurrences of zmem:
3393 remove_extra_zeroes();
3394 }
3395
3396 // Explore forward from in(start) to find the first fully initialized
3397 // word, and return its offset. Skip groups of subword stores which
3398 // together initialize full words. If in(start) is itself part of a
3399 // fully initialized word, return the offset of in(start). If there
3400 // are no following full-word stores, or if something is fishy, return
3401 // a negative value.
3402 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3403 int int_map = 0;
3404 intptr_t int_map_off = 0;
3405 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3406
3407 for (uint i = start, limit = req(); i < limit; i++) {
3408 Node* st = in(i);
3409
3410 intptr_t st_off = get_store_offset(st, phase);
3411 if (st_off < 0) break; // return conservative answer
3412
3413 int st_size = st->as_Store()->memory_size();
3414 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3415 return st_off; // we found a complete word init
3416 }
3417
3418 // update the map:
3419
3420 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3421 if (this_int_off != int_map_off) {
3422 // reset the map:
3423 int_map = 0;
3424 int_map_off = this_int_off;
3425 }
3426
3427 int subword_off = st_off - this_int_off;
3428 int_map |= right_n_bits(st_size) << subword_off;
3429 if ((int_map & FULL_MAP) == FULL_MAP) {
3430 return this_int_off; // we found a complete word init
3431 }
3432
3433 // Did this store hit or cross the word boundary?
3434 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3435 if (next_int_off == this_int_off + BytesPerInt) {
3436 // We passed the current int, without fully initializing it.
3437 int_map_off = next_int_off;
3438 int_map >>= BytesPerInt;
3439 } else if (next_int_off > this_int_off + BytesPerInt) {
3440 // We passed the current and next int.
3441 return this_int_off + BytesPerInt;
3442 }
3443 }
3444
3445 return -1;
3446 }
3447
3448
3449 // Called when the associated AllocateNode is expanded into CFG.
3450 // At this point, we may perform additional optimizations.
3451 // Linearize the stores by ascending offset, to make memory
3452 // activity as coherent as possible.
3453 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3454 intptr_t header_size,
3455 Node* size_in_bytes,
3456 PhaseGVN* phase) {
3457 assert(!is_complete(), "not already complete");
3458 assert(stores_are_sane(phase), "");
3459 assert(allocation() != NULL, "must be present");
3460
3461 remove_extra_zeroes();
3462
3463 if (ReduceFieldZeroing || ReduceBulkZeroing)
3464 // reduce instruction count for common initialization patterns
3465 coalesce_subword_stores(header_size, size_in_bytes, phase);
3466
3467 Node* zmem = zero_memory(); // initially zero memory state
3468 Node* inits = zmem; // accumulating a linearized chain of inits
3469 #ifdef ASSERT
3470 intptr_t first_offset = allocation()->minimum_header_size();
3471 intptr_t last_init_off = first_offset; // previous init offset
3472 intptr_t last_init_end = first_offset; // previous init offset+size
3473 intptr_t last_tile_end = first_offset; // previous tile offset+size
3474 #endif
3475 intptr_t zeroes_done = header_size;
3476
3477 bool do_zeroing = true; // we might give up if inits are very sparse
3478 int big_init_gaps = 0; // how many large gaps have we seen?
3479
3480 if (ZeroTLAB) do_zeroing = false;
3481 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3482
3483 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3484 Node* st = in(i);
3485 intptr_t st_off = get_store_offset(st, phase);
3486 if (st_off < 0)
3487 break; // unknown junk in the inits
3488 if (st->in(MemNode::Memory) != zmem)
3489 break; // complicated store chains somehow in list
3490
3491 int st_size = st->as_Store()->memory_size();
3492 intptr_t next_init_off = st_off + st_size;
3493
3494 if (do_zeroing && zeroes_done < next_init_off) {
3495 // See if this store needs a zero before it or under it.
3496 intptr_t zeroes_needed = st_off;
3497
3498 if (st_size < BytesPerInt) {
3499 // Look for subword stores which only partially initialize words.
3500 // If we find some, we must lay down some word-level zeroes first,
3501 // underneath the subword stores.
3502 //
3503 // Examples:
3504 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3505 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3506 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3507 //
3508 // Note: coalesce_subword_stores may have already done this,
3509 // if it was prompted by constant non-zero subword initializers.
3510 // But this case can still arise with non-constant stores.
3511
3512 intptr_t next_full_store = find_next_fullword_store(i, phase);
3513
3514 // In the examples above:
3515 // in(i) p q r s x y z
3516 // st_off 12 13 14 15 12 13 14
3517 // st_size 1 1 1 1 1 1 1
3518 // next_full_s. 12 16 16 16 16 16 16
3519 // z's_done 12 16 16 16 12 16 12
3520 // z's_needed 12 16 16 16 16 16 16
3521 // zsize 0 0 0 0 4 0 4
3522 if (next_full_store < 0) {
3523 // Conservative tack: Zero to end of current word.
3524 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3525 } else {
3526 // Zero to beginning of next fully initialized word.
3527 // Or, don't zero at all, if we are already in that word.
3528 assert(next_full_store >= zeroes_needed, "must go forward");
3529 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3530 zeroes_needed = next_full_store;
3531 }
3532 }
3533
3534 if (zeroes_needed > zeroes_done) {
3535 intptr_t zsize = zeroes_needed - zeroes_done;
3536 // Do some incremental zeroing on rawmem, in parallel with inits.
3537 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3538 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3539 zeroes_done, zeroes_needed,
3540 phase);
3541 zeroes_done = zeroes_needed;
3542 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3543 do_zeroing = false; // leave the hole, next time
3544 }
3545 }
3546
3547 // Collect the store and move on:
3548 st->set_req(MemNode::Memory, inits);
3549 inits = st; // put it on the linearized chain
3550 set_req(i, zmem); // unhook from previous position
3551
3552 if (zeroes_done == st_off)
3553 zeroes_done = next_init_off;
3554
3555 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3556
3557 #ifdef ASSERT
3558 // Various order invariants. Weaker than stores_are_sane because
3559 // a large constant tile can be filled in by smaller non-constant stores.
3560 assert(st_off >= last_init_off, "inits do not reverse");
3561 last_init_off = st_off;
3562 const Type* val = NULL;
3563 if (st_size >= BytesPerInt &&
3564 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3565 (int)val->basic_type() < (int)T_OBJECT) {
3566 assert(st_off >= last_tile_end, "tiles do not overlap");
3567 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3568 last_tile_end = MAX2(last_tile_end, next_init_off);
3569 } else {
3570 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3571 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3572 assert(st_off >= last_init_end, "inits do not overlap");
3573 last_init_end = next_init_off; // it's a non-tile
3574 }
3575 #endif //ASSERT
3576 }
3577
3578 remove_extra_zeroes(); // clear out all the zmems left over
3579 add_req(inits);
3580
3581 if (!ZeroTLAB) {
3582 // If anything remains to be zeroed, zero it all now.
3583 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3584 // if it is the last unused 4 bytes of an instance, forget about it
3585 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3586 if (zeroes_done + BytesPerLong >= size_limit) {
3587 assert(allocation() != NULL, "");
3588 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3589 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3590 if (zeroes_done == k->layout_helper())
3591 zeroes_done = size_limit;
3592 }
3593 if (zeroes_done < size_limit) {
3594 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3595 zeroes_done, size_in_bytes, phase);
3596 }
3597 }
3598
3599 set_complete(phase);
3600 return rawmem;
3601 }
3602
3603
3604 #ifdef ASSERT
3605 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3606 if (is_complete())
3607 return true; // stores could be anything at this point
3608 assert(allocation() != NULL, "must be present");
3609 intptr_t last_off = allocation()->minimum_header_size();
3610 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3611 Node* st = in(i);
3612 intptr_t st_off = get_store_offset(st, phase);
3613 if (st_off < 0) continue; // ignore dead garbage
3614 if (last_off > st_off) {
3615 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3616 this->dump(2);
3617 assert(false, "ascending store offsets");
3618 return false;
3619 }
3620 last_off = st_off + st->as_Store()->memory_size();
3621 }
3622 return true;
3623 }
3624 #endif //ASSERT
3625
3626
3627
3628
3629 //============================MergeMemNode=====================================
3630 //
3631 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3632 // contributing store or call operations. Each contributor provides the memory
3633 // state for a particular "alias type" (see Compile::alias_type). For example,
3634 // if a MergeMem has an input X for alias category #6, then any memory reference
3635 // to alias category #6 may use X as its memory state input, as an exact equivalent
3636 // to using the MergeMem as a whole.
3637 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3638 //
3639 // (Here, the <N> notation gives the index of the relevant adr_type.)
3640 //
3641 // In one special case (and more cases in the future), alias categories overlap.
3642 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3643 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3644 // it is exactly equivalent to that state W:
3645 // MergeMem(<Bot>: W) <==> W
3646 //
3647 // Usually, the merge has more than one input. In that case, where inputs
3648 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3649 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3650 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3651 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3652 //
3653 // A merge can take a "wide" memory state as one of its narrow inputs.
3654 // This simply means that the merge observes out only the relevant parts of
3655 // the wide input. That is, wide memory states arriving at narrow merge inputs
3656 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3657 //
3658 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3659 // and that memory slices "leak through":
3660 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3661 //
3662 // But, in such a cascade, repeated memory slices can "block the leak":
3663 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3664 //
3665 // In the last example, Y is not part of the combined memory state of the
3666 // outermost MergeMem. The system must, of course, prevent unschedulable
3667 // memory states from arising, so you can be sure that the state Y is somehow
3668 // a precursor to state Y'.
3669 //
3670 //
3671 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3672 // of each MergeMemNode array are exactly the numerical alias indexes, including
3673 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3674 // Compile::alias_type (and kin) produce and manage these indexes.
3675 //
3676 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3677 // (Note that this provides quick access to the top node inside MergeMem methods,
3678 // without the need to reach out via TLS to Compile::current.)
3679 //
3680 // As a consequence of what was just described, a MergeMem that represents a full
3681 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3682 // containing all alias categories.
3683 //
3684 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3685 //
3686 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3687 // a memory state for the alias type <N>, or else the top node, meaning that
3688 // there is no particular input for that alias type. Note that the length of
3689 // a MergeMem is variable, and may be extended at any time to accommodate new
3690 // memory states at larger alias indexes. When merges grow, they are of course
3691 // filled with "top" in the unused in() positions.
3692 //
3693 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3694 // (Top was chosen because it works smoothly with passes like GCM.)
3695 //
3696 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3697 // the type of random VM bits like TLS references.) Since it is always the
3698 // first non-Bot memory slice, some low-level loops use it to initialize an
3699 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3700 //
3701 //
3702 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3703 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3704 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3705 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3706 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3707 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3708 //
3709 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3710 // really that different from the other memory inputs. An abbreviation called
3711 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3712 //
3713 //
3714 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3715 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3716 // that "emerges though" the base memory will be marked as excluding the alias types
3717 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3718 //
3719 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3720 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3721 //
3722 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3723 // (It is currently unimplemented.) As you can see, the resulting merge is
3724 // actually a disjoint union of memory states, rather than an overlay.
3725 //
3726
3727 //------------------------------MergeMemNode-----------------------------------
3728 Node* MergeMemNode::make_empty_memory() {
3729 Node* empty_memory = (Node*) Compile::current()->top();
3730 assert(empty_memory->is_top(), "correct sentinel identity");
3731 return empty_memory;
3732 }
3733
3734 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3735 init_class_id(Class_MergeMem);
3736 // all inputs are nullified in Node::Node(int)
3737 // set_input(0, NULL); // no control input
3738
3739 // Initialize the edges uniformly to top, for starters.
3740 Node* empty_mem = make_empty_memory();
3741 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3742 init_req(i,empty_mem);
3743 }
3744 assert(empty_memory() == empty_mem, "");
3745
3746 if( new_base != NULL && new_base->is_MergeMem() ) {
3747 MergeMemNode* mdef = new_base->as_MergeMem();
3748 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3749 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3750 mms.set_memory(mms.memory2());
3751 }
3752 assert(base_memory() == mdef->base_memory(), "");
3753 } else {
3754 set_base_memory(new_base);
3755 }
3756 }
3757
3758 // Make a new, untransformed MergeMem with the same base as 'mem'.
3759 // If mem is itself a MergeMem, populate the result with the same edges.
3760 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3761 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3762 }
3763
3764 //------------------------------cmp--------------------------------------------
3765 uint MergeMemNode::hash() const { return NO_HASH; }
3766 uint MergeMemNode::cmp( const Node &n ) const {
3767 return (&n == this); // Always fail except on self
3768 }
3769
3770 //------------------------------Identity---------------------------------------
3771 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3772 // Identity if this merge point does not record any interesting memory
3773 // disambiguations.
3774 Node* base_mem = base_memory();
3775 Node* empty_mem = empty_memory();
3776 if (base_mem != empty_mem) { // Memory path is not dead?
3777 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3778 Node* mem = in(i);
3779 if (mem != empty_mem && mem != base_mem) {
3780 return this; // Many memory splits; no change
3781 }
3782 }
3783 }
3784 return base_mem; // No memory splits; ID on the one true input
3785 }
3786
3787 //------------------------------Ideal------------------------------------------
3788 // This method is invoked recursively on chains of MergeMem nodes
3789 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3790 // Remove chain'd MergeMems
3791 //
3792 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3793 // relative to the "in(Bot)". Since we are patching both at the same time,
3794 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3795 // but rewrite each "in(i)" relative to the new "in(Bot)".
3796 Node *progress = NULL;
3797
3798
3799 Node* old_base = base_memory();
3800 Node* empty_mem = empty_memory();
3801 if (old_base == empty_mem)
3802 return NULL; // Dead memory path.
3803
3804 MergeMemNode* old_mbase;
3805 if (old_base != NULL && old_base->is_MergeMem())
3806 old_mbase = old_base->as_MergeMem();
3807 else
3808 old_mbase = NULL;
3809 Node* new_base = old_base;
3810
3811 // simplify stacked MergeMems in base memory
3812 if (old_mbase) new_base = old_mbase->base_memory();
3813
3814 // the base memory might contribute new slices beyond my req()
3815 if (old_mbase) grow_to_match(old_mbase);
3816
3817 // Look carefully at the base node if it is a phi.
3818 PhiNode* phi_base;
3819 if (new_base != NULL && new_base->is_Phi())
3820 phi_base = new_base->as_Phi();
3821 else
3822 phi_base = NULL;
3823
3824 Node* phi_reg = NULL;
3825 uint phi_len = (uint)-1;
3826 if (phi_base != NULL && !phi_base->is_copy()) {
3827 // do not examine phi if degraded to a copy
3828 phi_reg = phi_base->region();
3829 phi_len = phi_base->req();
3830 // see if the phi is unfinished
3831 for (uint i = 1; i < phi_len; i++) {
3832 if (phi_base->in(i) == NULL) {
3833 // incomplete phi; do not look at it yet!
3834 phi_reg = NULL;
3835 phi_len = (uint)-1;
3836 break;
3837 }
3838 }
3839 }
3840
3841 // Note: We do not call verify_sparse on entry, because inputs
3842 // can normalize to the base_memory via subsume_node or similar
3843 // mechanisms. This method repairs that damage.
3844
3845 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3846
3847 // Look at each slice.
3848 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3849 Node* old_in = in(i);
3850 // calculate the old memory value
3851 Node* old_mem = old_in;
3852 if (old_mem == empty_mem) old_mem = old_base;
3853 assert(old_mem == memory_at(i), "");
3854
3855 // maybe update (reslice) the old memory value
3856
3857 // simplify stacked MergeMems
3858 Node* new_mem = old_mem;
3859 MergeMemNode* old_mmem;
3860 if (old_mem != NULL && old_mem->is_MergeMem())
3861 old_mmem = old_mem->as_MergeMem();
3862 else
3863 old_mmem = NULL;
3864 if (old_mmem == this) {
3865 // This can happen if loops break up and safepoints disappear.
3866 // A merge of BotPtr (default) with a RawPtr memory derived from a
3867 // safepoint can be rewritten to a merge of the same BotPtr with
3868 // the BotPtr phi coming into the loop. If that phi disappears
3869 // also, we can end up with a self-loop of the mergemem.
3870 // In general, if loops degenerate and memory effects disappear,
3871 // a mergemem can be left looking at itself. This simply means
3872 // that the mergemem's default should be used, since there is
3873 // no longer any apparent effect on this slice.
3874 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3875 // from start. Update the input to TOP.
3876 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3877 }
3878 else if (old_mmem != NULL) {
3879 new_mem = old_mmem->memory_at(i);
3880 }
3881 // else preceding memory was not a MergeMem
3882
3883 // replace equivalent phis (unfortunately, they do not GVN together)
3884 if (new_mem != NULL && new_mem != new_base &&
3885 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3886 if (new_mem->is_Phi()) {
3887 PhiNode* phi_mem = new_mem->as_Phi();
3888 for (uint i = 1; i < phi_len; i++) {
3889 if (phi_base->in(i) != phi_mem->in(i)) {
3890 phi_mem = NULL;
3891 break;
3892 }
3893 }
3894 if (phi_mem != NULL) {
3895 // equivalent phi nodes; revert to the def
3896 new_mem = new_base;
3897 }
3898 }
3899 }
3900
3901 // maybe store down a new value
3902 Node* new_in = new_mem;
3903 if (new_in == new_base) new_in = empty_mem;
3904
3905 if (new_in != old_in) {
3906 // Warning: Do not combine this "if" with the previous "if"
3907 // A memory slice might have be be rewritten even if it is semantically
3908 // unchanged, if the base_memory value has changed.
3909 set_req(i, new_in);
3910 progress = this; // Report progress
3911 }
3912 }
3913
3914 if (new_base != old_base) {
3915 set_req(Compile::AliasIdxBot, new_base);
3916 // Don't use set_base_memory(new_base), because we need to update du.
3917 assert(base_memory() == new_base, "");
3918 progress = this;
3919 }
3920
3921 if( base_memory() == this ) {
3922 // a self cycle indicates this memory path is dead
3923 set_req(Compile::AliasIdxBot, empty_mem);
3924 }
3925
3926 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3927 // Recursion must occur after the self cycle check above
3928 if( base_memory()->is_MergeMem() ) {
3929 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3930 Node *m = phase->transform(new_mbase); // Rollup any cycles
3931 if( m != NULL && (m->is_top() ||
3932 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3933 // propagate rollup of dead cycle to self
3934 set_req(Compile::AliasIdxBot, empty_mem);
3935 }
3936 }
3937
3938 if( base_memory() == empty_mem ) {
3939 progress = this;
3940 // Cut inputs during Parse phase only.
3941 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3942 if( !can_reshape ) {
3943 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3944 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3945 }
3946 }
3947 }
3948
3949 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3950 // Check if PhiNode::Ideal's "Split phis through memory merges"
3951 // transform should be attempted. Look for this->phi->this cycle.
3952 uint merge_width = req();
3953 if (merge_width > Compile::AliasIdxRaw) {
3954 PhiNode* phi = base_memory()->as_Phi();
3955 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3956 if (phi->in(i) == this) {
3957 phase->is_IterGVN()->_worklist.push(phi);
3958 break;
3959 }
3960 }
3961 }
3962 }
3963
3964 assert(progress || verify_sparse(), "please, no dups of base");
3965 return progress;
3966 }
3967
3968 //-------------------------set_base_memory-------------------------------------
3969 void MergeMemNode::set_base_memory(Node *new_base) {
3970 Node* empty_mem = empty_memory();
3971 set_req(Compile::AliasIdxBot, new_base);
3972 assert(memory_at(req()) == new_base, "must set default memory");
3973 // Clear out other occurrences of new_base:
3974 if (new_base != empty_mem) {
3975 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3976 if (in(i) == new_base) set_req(i, empty_mem);
3977 }
3978 }
3979 }
3980
3981 //------------------------------out_RegMask------------------------------------
3982 const RegMask &MergeMemNode::out_RegMask() const {
3983 return RegMask::Empty;
3984 }
3985
3986 //------------------------------dump_spec--------------------------------------
3987 #ifndef PRODUCT
3988 void MergeMemNode::dump_spec(outputStream *st) const {
3989 st->print(" {");
3990 Node* base_mem = base_memory();
3991 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3992 Node* mem = memory_at(i);
3993 if (mem == base_mem) { st->print(" -"); continue; }
3994 st->print( " N%d:", mem->_idx );
3995 Compile::current()->get_adr_type(i)->dump_on(st);
3996 }
3997 st->print(" }");
3998 }
3999 #endif // !PRODUCT
4000
4001
4002 #ifdef ASSERT
4003 static bool might_be_same(Node* a, Node* b) {
4004 if (a == b) return true;
4005 if (!(a->is_Phi() || b->is_Phi())) return false;
4006 // phis shift around during optimization
4007 return true; // pretty stupid...
4008 }
4009
4010 // verify a narrow slice (either incoming or outgoing)
4011 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4012 if (!VerifyAliases) return; // don't bother to verify unless requested
4013 if (is_error_reported()) return; // muzzle asserts when debugging an error
4014 if (Node::in_dump()) return; // muzzle asserts when printing
4015 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4016 assert(n != NULL, "");
4017 // Elide intervening MergeMem's
4018 while (n->is_MergeMem()) {
4019 n = n->as_MergeMem()->memory_at(alias_idx);
4020 }
4021 Compile* C = Compile::current();
4022 const TypePtr* n_adr_type = n->adr_type();
4023 if (n == m->empty_memory()) {
4024 // Implicit copy of base_memory()
4025 } else if (n_adr_type != TypePtr::BOTTOM) {
4026 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4027 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4028 } else {
4029 // A few places like make_runtime_call "know" that VM calls are narrow,
4030 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4031 bool expected_wide_mem = false;
4032 if (n == m->base_memory()) {
4033 expected_wide_mem = true;
4034 } else if (alias_idx == Compile::AliasIdxRaw ||
4035 n == m->memory_at(Compile::AliasIdxRaw)) {
4036 expected_wide_mem = true;
4037 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4038 // memory can "leak through" calls on channels that
4039 // are write-once. Allow this also.
4040 expected_wide_mem = true;
4041 }
4042 assert(expected_wide_mem, "expected narrow slice replacement");
4043 }
4044 }
4045 #else // !ASSERT
4046 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4047 #endif
4048
4049
4050 //-----------------------------memory_at---------------------------------------
4051 Node* MergeMemNode::memory_at(uint alias_idx) const {
4052 assert(alias_idx >= Compile::AliasIdxRaw ||
4053 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4054 "must avoid base_memory and AliasIdxTop");
4055
4056 // Otherwise, it is a narrow slice.
4057 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4058 Compile *C = Compile::current();
4059 if (is_empty_memory(n)) {
4060 // the array is sparse; empty slots are the "top" node
4061 n = base_memory();
4062 assert(Node::in_dump()
4063 || n == NULL || n->bottom_type() == Type::TOP
4064 || n->adr_type() == TypePtr::BOTTOM
4065 || n->adr_type() == TypeRawPtr::BOTTOM
4066 || Compile::current()->AliasLevel() == 0,
4067 "must be a wide memory");
4068 // AliasLevel == 0 if we are organizing the memory states manually.
4069 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4070 } else {
4071 // make sure the stored slice is sane
4072 #ifdef ASSERT
4073 if (is_error_reported() || Node::in_dump()) {
4074 } else if (might_be_same(n, base_memory())) {
4075 // Give it a pass: It is a mostly harmless repetition of the base.
4076 // This can arise normally from node subsumption during optimization.
4077 } else {
4078 verify_memory_slice(this, alias_idx, n);
4079 }
4080 #endif
4081 }
4082 return n;
4083 }
4084
4085 //---------------------------set_memory_at-------------------------------------
4086 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4087 verify_memory_slice(this, alias_idx, n);
4088 Node* empty_mem = empty_memory();
4089 if (n == base_memory()) n = empty_mem; // collapse default
4090 uint need_req = alias_idx+1;
4091 if (req() < need_req) {
4092 if (n == empty_mem) return; // already the default, so do not grow me
4093 // grow the sparse array
4094 do {
4095 add_req(empty_mem);
4096 } while (req() < need_req);
4097 }
4098 set_req( alias_idx, n );
4099 }
4100
4101
4102
4103 //--------------------------iteration_setup------------------------------------
4104 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4105 if (other != NULL) {
4106 grow_to_match(other);
4107 // invariant: the finite support of mm2 is within mm->req()
4108 #ifdef ASSERT
4109 for (uint i = req(); i < other->req(); i++) {
4110 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4111 }
4112 #endif
4113 }
4114 // Replace spurious copies of base_memory by top.
4115 Node* base_mem = base_memory();
4116 if (base_mem != NULL && !base_mem->is_top()) {
4117 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4118 if (in(i) == base_mem)
4119 set_req(i, empty_memory());
4120 }
4121 }
4122 }
4123
4124 //---------------------------grow_to_match-------------------------------------
4125 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4126 Node* empty_mem = empty_memory();
4127 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4128 // look for the finite support of the other memory
4129 for (uint i = other->req(); --i >= req(); ) {
4130 if (other->in(i) != empty_mem) {
4131 uint new_len = i+1;
4132 while (req() < new_len) add_req(empty_mem);
4133 break;
4134 }
4135 }
4136 }
4137
4138 //---------------------------verify_sparse-------------------------------------
4139 #ifndef PRODUCT
4140 bool MergeMemNode::verify_sparse() const {
4141 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4142 Node* base_mem = base_memory();
4143 // The following can happen in degenerate cases, since empty==top.
4144 if (is_empty_memory(base_mem)) return true;
4145 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4146 assert(in(i) != NULL, "sane slice");
4147 if (in(i) == base_mem) return false; // should have been the sentinel value!
4148 }
4149 return true;
4150 }
4151
4152 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4153 Node* n;
4154 n = mm->in(idx);
4155 if (mem == n) return true; // might be empty_memory()
4156 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4157 if (mem == n) return true;
4158 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4159 if (mem == n) return true;
4160 if (n == NULL) break;
4161 }
4162 return false;
4163 }
4164 #endif // !PRODUCT