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