1 /*
2 * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
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_instance_field())
95 return mchain; // don't try to optimize non-instance types
96 uint instance_id = tinst->instance_id();
97 Node *prev = NULL;
98 Node *result = mchain;
99 while (prev != result) {
100 prev = result;
101 // skip over a call which does not affect this memory slice
102 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
103 Node *proj_in = result->in(0);
104 if (proj_in->is_Call()) {
105 CallNode *call = proj_in->as_Call();
106 if (!call->may_modify(t_adr, phase)) {
107 result = call->in(TypeFunc::Memory);
108 }
109 } else if (proj_in->is_Initialize()) {
110 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
111 // Stop if this is the initialization for the object instance which
112 // which contains this memory slice, otherwise skip over it.
113 if (alloc != NULL && alloc->_idx != instance_id) {
114 result = proj_in->in(TypeFunc::Memory);
115 }
116 } else if (proj_in->is_MemBar()) {
117 result = proj_in->in(TypeFunc::Memory);
118 }
119 } else if (result->is_MergeMem()) {
120 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
121 }
122 }
123 return result;
124 }
125
126 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
127 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
128 bool is_instance = (t_oop != NULL) && t_oop->is_instance_field();
129 PhaseIterGVN *igvn = phase->is_IterGVN();
130 Node *result = mchain;
131 result = optimize_simple_memory_chain(result, t_adr, phase);
132 if (is_instance && igvn != NULL && result->is_Phi()) {
133 PhiNode *mphi = result->as_Phi();
134 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
135 const TypePtr *t = mphi->adr_type();
136 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
137 t->isa_oopptr() && !t->is_oopptr()->is_instance() &&
138 t->is_oopptr()->cast_to_instance(t_oop->instance_id()) == t_oop) {
139 // clone the Phi with our address type
140 result = mphi->split_out_instance(t_adr, igvn);
141 } else {
142 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
143 }
144 }
145 return result;
146 }
147
148 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
149 uint alias_idx = phase->C->get_alias_index(tp);
150 Node *mem = mmem;
151 #ifdef ASSERT
152 {
153 // Check that current type is consistent with the alias index used during graph construction
154 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
155 bool consistent = adr_check == NULL || adr_check->empty() ||
156 phase->C->must_alias(adr_check, alias_idx );
157 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
158 if( !consistent && adr_check != NULL && !adr_check->empty() &&
159 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
160 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
161 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
162 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
163 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
164 // don't assert if it is dead code.
165 consistent = true;
166 }
167 if( !consistent ) {
168 st->print("alias_idx==%d, adr_check==", alias_idx);
169 if( adr_check == NULL ) {
170 st->print("NULL");
171 } else {
172 adr_check->dump();
173 }
174 st->cr();
175 print_alias_types();
176 assert(consistent, "adr_check must match alias idx");
177 }
178 }
179 #endif
180 // TypeInstPtr::NOTNULL+any is an OOP with unknown offset - generally
181 // means an array I have not precisely typed yet. Do not do any
182 // alias stuff with it any time soon.
183 const TypeOopPtr *tinst = tp->isa_oopptr();
184 if( tp->base() != Type::AnyPtr &&
185 !(tinst &&
186 tinst->klass()->is_java_lang_Object() &&
187 tinst->offset() == Type::OffsetBot) ) {
188 // compress paths and change unreachable cycles to TOP
189 // If not, we can update the input infinitely along a MergeMem cycle
190 // Equivalent code in PhiNode::Ideal
191 Node* m = phase->transform(mmem);
192 // If tranformed to a MergeMem, get the desired slice
193 // Otherwise the returned node represents memory for every slice
194 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
195 // Update input if it is progress over what we have now
196 }
197 return mem;
198 }
199
200 //--------------------------Ideal_common---------------------------------------
201 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
202 // Unhook non-raw memories from complete (macro-expanded) initializations.
203 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
204 // If our control input is a dead region, kill all below the region
205 Node *ctl = in(MemNode::Control);
206 if (ctl && remove_dead_region(phase, can_reshape))
207 return this;
208
209 // Ignore if memory is dead, or self-loop
210 Node *mem = in(MemNode::Memory);
211 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
212 assert( mem != this, "dead loop in MemNode::Ideal" );
213
214 Node *address = in(MemNode::Address);
215 const Type *t_adr = phase->type( address );
216 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
217
218 // Avoid independent memory operations
219 Node* old_mem = mem;
220
221 // The code which unhooks non-raw memories from complete (macro-expanded)
222 // initializations was removed. After macro-expansion all stores catched
223 // by Initialize node became raw stores and there is no information
224 // which memory slices they modify. So it is unsafe to move any memory
225 // operation above these stores. Also in most cases hooked non-raw memories
226 // were already unhooked by using information from detect_ptr_independence()
227 // and find_previous_store().
228
229 if (mem->is_MergeMem()) {
230 MergeMemNode* mmem = mem->as_MergeMem();
231 const TypePtr *tp = t_adr->is_ptr();
232
233 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
234 }
235
236 if (mem != old_mem) {
237 set_req(MemNode::Memory, mem);
238 return this;
239 }
240
241 // let the subclass continue analyzing...
242 return NULL;
243 }
244
245 // Helper function for proving some simple control dominations.
246 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
247 // Already assumes that 'dom' is available at 'sub', and that 'sub'
248 // is not a constant (dominated by the method's StartNode).
249 // Used by MemNode::find_previous_store to prove that the
250 // control input of a memory operation predates (dominates)
251 // an allocation it wants to look past.
252 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
253 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
254 return false; // Conservative answer for dead code
255
256 // Check 'dom'.
257 dom = dom->find_exact_control(dom);
258 if (dom == NULL || dom->is_top())
259 return false; // Conservative answer for dead code
260
261 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
262 return true;
263
264 // 'dom' dominates 'sub' if its control edge and control edges
265 // of all its inputs dominate or equal to sub's control edge.
266
267 // Currently 'sub' is either Allocate, Initialize or Start nodes.
268 // Or Region for the check in LoadNode::Ideal();
269 // 'sub' should have sub->in(0) != NULL.
270 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
271 sub->is_Region(), "expecting only these nodes");
272
273 // Get control edge of 'sub'.
274 sub = sub->find_exact_control(sub->in(0));
275 if (sub == NULL || sub->is_top())
276 return false; // Conservative answer for dead code
277
278 assert(sub->is_CFG(), "expecting control");
279
280 if (sub == dom)
281 return true;
282
283 if (sub->is_Start() || sub->is_Root())
284 return false;
285
286 {
287 // Check all control edges of 'dom'.
288
289 ResourceMark rm;
290 Arena* arena = Thread::current()->resource_area();
291 Node_List nlist(arena);
292 Unique_Node_List dom_list(arena);
293
294 dom_list.push(dom);
295 bool only_dominating_controls = false;
296
297 for (uint next = 0; next < dom_list.size(); next++) {
298 Node* n = dom_list.at(next);
299 if (!n->is_CFG() && n->pinned()) {
300 // Check only own control edge for pinned non-control nodes.
301 n = n->find_exact_control(n->in(0));
302 if (n == NULL || n->is_top())
303 return false; // Conservative answer for dead code
304 assert(n->is_CFG(), "expecting control");
305 }
306 if (n->is_Con() || n->is_Start() || n->is_Root()) {
307 only_dominating_controls = true;
308 } else if (n->is_CFG()) {
309 if (n->dominates(sub, nlist))
310 only_dominating_controls = true;
311 else
312 return false;
313 } else {
314 // First, own control edge.
315 Node* m = n->find_exact_control(n->in(0));
316 if (m != NULL) {
317 if (m->is_top())
318 return false; // Conservative answer for dead code
319 dom_list.push(m);
320 }
321 // Now, the rest of edges.
322 uint cnt = n->req();
323 for (uint i = 1; i < cnt; i++) {
324 m = n->find_exact_control(n->in(i));
325 if (m == NULL || m->is_top())
326 continue;
327 dom_list.push(m);
328 }
329 }
330 }
331 return only_dominating_controls;
332 }
333 }
334
335 //---------------------detect_ptr_independence---------------------------------
336 // Used by MemNode::find_previous_store to prove that two base
337 // pointers are never equal.
338 // The pointers are accompanied by their associated allocations,
339 // if any, which have been previously discovered by the caller.
340 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
341 Node* p2, AllocateNode* a2,
342 PhaseTransform* phase) {
343 // Attempt to prove that these two pointers cannot be aliased.
344 // They may both manifestly be allocations, and they should differ.
345 // Or, if they are not both allocations, they can be distinct constants.
346 // Otherwise, one is an allocation and the other a pre-existing value.
347 if (a1 == NULL && a2 == NULL) { // neither an allocation
348 return (p1 != p2) && p1->is_Con() && p2->is_Con();
349 } else if (a1 != NULL && a2 != NULL) { // both allocations
350 return (a1 != a2);
351 } else if (a1 != NULL) { // one allocation a1
352 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
353 return all_controls_dominate(p2, a1);
354 } else { //(a2 != NULL) // one allocation a2
355 return all_controls_dominate(p1, a2);
356 }
357 return false;
358 }
359
360
361 // The logic for reordering loads and stores uses four steps:
362 // (a) Walk carefully past stores and initializations which we
363 // can prove are independent of this load.
364 // (b) Observe that the next memory state makes an exact match
365 // with self (load or store), and locate the relevant store.
366 // (c) Ensure that, if we were to wire self directly to the store,
367 // the optimizer would fold it up somehow.
368 // (d) Do the rewiring, and return, depending on some other part of
369 // the optimizer to fold up the load.
370 // This routine handles steps (a) and (b). Steps (c) and (d) are
371 // specific to loads and stores, so they are handled by the callers.
372 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
373 //
374 Node* MemNode::find_previous_store(PhaseTransform* phase) {
375 Node* ctrl = in(MemNode::Control);
376 Node* adr = in(MemNode::Address);
377 intptr_t offset = 0;
378 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
379 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
380
381 if (offset == Type::OffsetBot)
382 return NULL; // cannot unalias unless there are precise offsets
383
384 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
385
386 intptr_t size_in_bytes = memory_size();
387
388 Node* mem = in(MemNode::Memory); // start searching here...
389
390 int cnt = 50; // Cycle limiter
391 for (;;) { // While we can dance past unrelated stores...
392 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
393
394 if (mem->is_Store()) {
395 Node* st_adr = mem->in(MemNode::Address);
396 intptr_t st_offset = 0;
397 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
398 if (st_base == NULL)
399 break; // inscrutable pointer
400 if (st_offset != offset && st_offset != Type::OffsetBot) {
401 const int MAX_STORE = BytesPerLong;
402 if (st_offset >= offset + size_in_bytes ||
403 st_offset <= offset - MAX_STORE ||
404 st_offset <= offset - mem->as_Store()->memory_size()) {
405 // Success: The offsets are provably independent.
406 // (You may ask, why not just test st_offset != offset and be done?
407 // The answer is that stores of different sizes can co-exist
408 // in the same sequence of RawMem effects. We sometimes initialize
409 // a whole 'tile' of array elements with a single jint or jlong.)
410 mem = mem->in(MemNode::Memory);
411 continue; // (a) advance through independent store memory
412 }
413 }
414 if (st_base != base &&
415 detect_ptr_independence(base, alloc,
416 st_base,
417 AllocateNode::Ideal_allocation(st_base, phase),
418 phase)) {
419 // Success: The bases are provably independent.
420 mem = mem->in(MemNode::Memory);
421 continue; // (a) advance through independent store memory
422 }
423
424 // (b) At this point, if the bases or offsets do not agree, we lose,
425 // since we have not managed to prove 'this' and 'mem' independent.
426 if (st_base == base && st_offset == offset) {
427 return mem; // let caller handle steps (c), (d)
428 }
429
430 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
431 InitializeNode* st_init = mem->in(0)->as_Initialize();
432 AllocateNode* st_alloc = st_init->allocation();
433 if (st_alloc == NULL)
434 break; // something degenerated
435 bool known_identical = false;
436 bool known_independent = false;
437 if (alloc == st_alloc)
438 known_identical = true;
439 else if (alloc != NULL)
440 known_independent = true;
441 else if (all_controls_dominate(this, st_alloc))
442 known_independent = true;
443
444 if (known_independent) {
445 // The bases are provably independent: Either they are
446 // manifestly distinct allocations, or else the control
447 // of this load dominates the store's allocation.
448 int alias_idx = phase->C->get_alias_index(adr_type());
449 if (alias_idx == Compile::AliasIdxRaw) {
450 mem = st_alloc->in(TypeFunc::Memory);
451 } else {
452 mem = st_init->memory(alias_idx);
453 }
454 continue; // (a) advance through independent store memory
455 }
456
457 // (b) at this point, if we are not looking at a store initializing
458 // the same allocation we are loading from, we lose.
459 if (known_identical) {
460 // From caller, can_see_stored_value will consult find_captured_store.
461 return mem; // let caller handle steps (c), (d)
462 }
463
464 } else if (addr_t != NULL && addr_t->is_instance_field()) {
465 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
466 if (mem->is_Proj() && mem->in(0)->is_Call()) {
467 CallNode *call = mem->in(0)->as_Call();
468 if (!call->may_modify(addr_t, phase)) {
469 mem = call->in(TypeFunc::Memory);
470 continue; // (a) advance through independent call memory
471 }
472 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
473 mem = mem->in(0)->in(TypeFunc::Memory);
474 continue; // (a) advance through independent MemBar memory
475 } else if (mem->is_MergeMem()) {
476 int alias_idx = phase->C->get_alias_index(adr_type());
477 mem = mem->as_MergeMem()->memory_at(alias_idx);
478 continue; // (a) advance through independent MergeMem memory
479 }
480 }
481
482 // Unless there is an explicit 'continue', we must bail out here,
483 // because 'mem' is an inscrutable memory state (e.g., a call).
484 break;
485 }
486
487 return NULL; // bail out
488 }
489
490 //----------------------calculate_adr_type-------------------------------------
491 // Helper function. Notices when the given type of address hits top or bottom.
492 // Also, asserts a cross-check of the type against the expected address type.
493 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
494 if (t == Type::TOP) return NULL; // does not touch memory any more?
495 #ifdef PRODUCT
496 cross_check = NULL;
497 #else
498 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
499 #endif
500 const TypePtr* tp = t->isa_ptr();
501 if (tp == NULL) {
502 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
503 return TypePtr::BOTTOM; // touches lots of memory
504 } else {
505 #ifdef ASSERT
506 // %%%% [phh] We don't check the alias index if cross_check is
507 // TypeRawPtr::BOTTOM. Needs to be investigated.
508 if (cross_check != NULL &&
509 cross_check != TypePtr::BOTTOM &&
510 cross_check != TypeRawPtr::BOTTOM) {
511 // Recheck the alias index, to see if it has changed (due to a bug).
512 Compile* C = Compile::current();
513 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
514 "must stay in the original alias category");
515 // The type of the address must be contained in the adr_type,
516 // disregarding "null"-ness.
517 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
518 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
519 assert(cross_check->meet(tp_notnull) == cross_check,
520 "real address must not escape from expected memory type");
521 }
522 #endif
523 return tp;
524 }
525 }
526
527 //------------------------adr_phi_is_loop_invariant----------------------------
528 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
529 // loop is loop invariant. Make a quick traversal of Phi and associated
530 // CastPP nodes, looking to see if they are a closed group within the loop.
531 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
532 // The idea is that the phi-nest must boil down to only CastPP nodes
533 // with the same data. This implies that any path into the loop already
534 // includes such a CastPP, and so the original cast, whatever its input,
535 // must be covered by an equivalent cast, with an earlier control input.
536 ResourceMark rm;
537
538 // The loop entry input of the phi should be the unique dominating
539 // node for every Phi/CastPP in the loop.
540 Unique_Node_List closure;
541 closure.push(adr_phi->in(LoopNode::EntryControl));
542
543 // Add the phi node and the cast to the worklist.
544 Unique_Node_List worklist;
545 worklist.push(adr_phi);
546 if( cast != NULL ){
547 if( !cast->is_ConstraintCast() ) return false;
548 worklist.push(cast);
549 }
550
551 // Begin recursive walk of phi nodes.
552 while( worklist.size() ){
553 // Take a node off the worklist
554 Node *n = worklist.pop();
555 if( !closure.member(n) ){
556 // Add it to the closure.
557 closure.push(n);
558 // Make a sanity check to ensure we don't waste too much time here.
559 if( closure.size() > 20) return false;
560 // This node is OK if:
561 // - it is a cast of an identical value
562 // - or it is a phi node (then we add its inputs to the worklist)
563 // Otherwise, the node is not OK, and we presume the cast is not invariant
564 if( n->is_ConstraintCast() ){
565 worklist.push(n->in(1));
566 } else if( n->is_Phi() ) {
567 for( uint i = 1; i < n->req(); i++ ) {
568 worklist.push(n->in(i));
569 }
570 } else {
571 return false;
572 }
573 }
574 }
575
576 // Quit when the worklist is empty, and we've found no offending nodes.
577 return true;
578 }
579
580 //------------------------------Ideal_DU_postCCP-------------------------------
581 // Find any cast-away of null-ness and keep its control. Null cast-aways are
582 // going away in this pass and we need to make this memory op depend on the
583 // gating null check.
584 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
585 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
586 }
587
588 // I tried to leave the CastPP's in. This makes the graph more accurate in
589 // some sense; we get to keep around the knowledge that an oop is not-null
590 // after some test. Alas, the CastPP's interfere with GVN (some values are
591 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
592 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
593 // some of the more trivial cases in the optimizer. Removing more useless
594 // Phi's started allowing Loads to illegally float above null checks. I gave
595 // up on this approach. CNC 10/20/2000
596 // This static method may be called not from MemNode (EncodePNode calls it).
597 // Only the control edge of the node 'n' might be updated.
598 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
599 Node *skipped_cast = NULL;
600 // Need a null check? Regular static accesses do not because they are
601 // from constant addresses. Array ops are gated by the range check (which
602 // always includes a NULL check). Just check field ops.
603 if( n->in(MemNode::Control) == NULL ) {
604 // Scan upwards for the highest location we can place this memory op.
605 while( true ) {
606 switch( adr->Opcode() ) {
607
608 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
609 adr = adr->in(AddPNode::Base);
610 continue;
611
612 case Op_DecodeN: // No change to NULL-ness, so peek thru
613 adr = adr->in(1);
614 continue;
615
616 case Op_CastPP:
617 // If the CastPP is useless, just peek on through it.
618 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
619 // Remember the cast that we've peeked though. If we peek
620 // through more than one, then we end up remembering the highest
621 // one, that is, if in a loop, the one closest to the top.
622 skipped_cast = adr;
623 adr = adr->in(1);
624 continue;
625 }
626 // CastPP is going away in this pass! We need this memory op to be
627 // control-dependent on the test that is guarding the CastPP.
628 ccp->hash_delete(n);
629 n->set_req(MemNode::Control, adr->in(0));
630 ccp->hash_insert(n);
631 return n;
632
633 case Op_Phi:
634 // Attempt to float above a Phi to some dominating point.
635 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
636 // If we've already peeked through a Cast (which could have set the
637 // control), we can't float above a Phi, because the skipped Cast
638 // may not be loop invariant.
639 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
640 adr = adr->in(1);
641 continue;
642 }
643 }
644
645 // Intentional fallthrough!
646
647 // No obvious dominating point. The mem op is pinned below the Phi
648 // by the Phi itself. If the Phi goes away (no true value is merged)
649 // then the mem op can float, but not indefinitely. It must be pinned
650 // behind the controls leading to the Phi.
651 case Op_CheckCastPP:
652 // These usually stick around to change address type, however a
653 // useless one can be elided and we still need to pick up a control edge
654 if (adr->in(0) == NULL) {
655 // This CheckCastPP node has NO control and is likely useless. But we
656 // need check further up the ancestor chain for a control input to keep
657 // the node in place. 4959717.
658 skipped_cast = adr;
659 adr = adr->in(1);
660 continue;
661 }
662 ccp->hash_delete(n);
663 n->set_req(MemNode::Control, adr->in(0));
664 ccp->hash_insert(n);
665 return n;
666
667 // List of "safe" opcodes; those that implicitly block the memory
668 // op below any null check.
669 case Op_CastX2P: // no null checks on native pointers
670 case Op_Parm: // 'this' pointer is not null
671 case Op_LoadP: // Loading from within a klass
672 case Op_LoadN: // Loading from within a klass
673 case Op_LoadKlass: // Loading from within a klass
674 case Op_LoadNKlass: // Loading from within a klass
675 case Op_ConP: // Loading from a klass
676 case Op_ConN: // Loading from a klass
677 case Op_CreateEx: // Sucking up the guts of an exception oop
678 case Op_Con: // Reading from TLS
679 case Op_CMoveP: // CMoveP is pinned
680 case Op_CMoveN: // CMoveN is pinned
681 break; // No progress
682
683 case Op_Proj: // Direct call to an allocation routine
684 case Op_SCMemProj: // Memory state from store conditional ops
685 #ifdef ASSERT
686 {
687 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
688 const Node* call = adr->in(0);
689 if (call->is_CallJava()) {
690 const CallJavaNode* call_java = call->as_CallJava();
691 const TypeTuple *r = call_java->tf()->range();
692 assert(r->cnt() > TypeFunc::Parms, "must return value");
693 const Type* ret_type = r->field_at(TypeFunc::Parms);
694 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
695 // We further presume that this is one of
696 // new_instance_Java, new_array_Java, or
697 // the like, but do not assert for this.
698 } else if (call->is_Allocate()) {
699 // similar case to new_instance_Java, etc.
700 } else if (!call->is_CallLeaf()) {
701 // Projections from fetch_oop (OSR) are allowed as well.
702 ShouldNotReachHere();
703 }
704 }
705 #endif
706 break;
707 default:
708 ShouldNotReachHere();
709 }
710 break;
711 }
712 }
713
714 return NULL; // No progress
715 }
716
717
718 //=============================================================================
719 uint LoadNode::size_of() const { return sizeof(*this); }
720 uint LoadNode::cmp( const Node &n ) const
721 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
722 const Type *LoadNode::bottom_type() const { return _type; }
723 uint LoadNode::ideal_reg() const {
724 return Matcher::base2reg[_type->base()];
725 }
726
727 #ifndef PRODUCT
728 void LoadNode::dump_spec(outputStream *st) const {
729 MemNode::dump_spec(st);
730 if( !Verbose && !WizardMode ) {
731 // standard dump does this in Verbose and WizardMode
732 st->print(" #"); _type->dump_on(st);
733 }
734 }
735 #endif
736
737
738 //----------------------------LoadNode::make-----------------------------------
739 // Polymorphic factory method:
740 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
741 Compile* C = gvn.C;
742
743 // sanity check the alias category against the created node type
744 assert(!(adr_type->isa_oopptr() &&
745 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
746 "use LoadKlassNode instead");
747 assert(!(adr_type->isa_aryptr() &&
748 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
749 "use LoadRangeNode instead");
750 switch (bt) {
751 case T_BOOLEAN:
752 case T_BYTE: return new (C, 3) LoadBNode(ctl, mem, adr, adr_type, rt->is_int() );
753 case T_INT: return new (C, 3) LoadINode(ctl, mem, adr, adr_type, rt->is_int() );
754 case T_CHAR: return new (C, 3) LoadCNode(ctl, mem, adr, adr_type, rt->is_int() );
755 case T_SHORT: return new (C, 3) LoadSNode(ctl, mem, adr, adr_type, rt->is_int() );
756 case T_LONG: return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long() );
757 case T_FLOAT: return new (C, 3) LoadFNode(ctl, mem, adr, adr_type, rt );
758 case T_DOUBLE: return new (C, 3) LoadDNode(ctl, mem, adr, adr_type, rt );
759 case T_ADDRESS: return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr() );
760 case T_OBJECT:
761 #ifdef _LP64
762 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
763 const TypeNarrowOop* narrowtype;
764 if (rt->isa_narrowoop()) {
765 narrowtype = rt->is_narrowoop();
766 } else {
767 narrowtype = rt->is_oopptr()->make_narrowoop();
768 }
769 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, narrowtype));
770
771 return DecodeNNode::decode(&gvn, load);
772 } else
773 #endif
774 {
775 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
776 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
777 }
778 }
779 ShouldNotReachHere();
780 return (LoadNode*)NULL;
781 }
782
783 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
784 bool require_atomic = true;
785 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
786 }
787
788
789
790
791 //------------------------------hash-------------------------------------------
792 uint LoadNode::hash() const {
793 // unroll addition of interesting fields
794 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
795 }
796
797 //---------------------------can_see_stored_value------------------------------
798 // This routine exists to make sure this set of tests is done the same
799 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
800 // will change the graph shape in a way which makes memory alive twice at the
801 // same time (uses the Oracle model of aliasing), then some
802 // LoadXNode::Identity will fold things back to the equivalence-class model
803 // of aliasing.
804 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
805 Node* ld_adr = in(MemNode::Address);
806
807 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
808 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
809 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
810 atp->field() != NULL && !atp->field()->is_volatile()) {
811 uint alias_idx = atp->index();
812 bool final = atp->field()->is_final();
813 Node* result = NULL;
814 Node* current = st;
815 // Skip through chains of MemBarNodes checking the MergeMems for
816 // new states for the slice of this load. Stop once any other
817 // kind of node is encountered. Loads from final memory can skip
818 // through any kind of MemBar but normal loads shouldn't skip
819 // through MemBarAcquire since the could allow them to move out of
820 // a synchronized region.
821 while (current->is_Proj()) {
822 int opc = current->in(0)->Opcode();
823 if ((final && opc == Op_MemBarAcquire) ||
824 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
825 Node* mem = current->in(0)->in(TypeFunc::Memory);
826 if (mem->is_MergeMem()) {
827 MergeMemNode* merge = mem->as_MergeMem();
828 Node* new_st = merge->memory_at(alias_idx);
829 if (new_st == merge->base_memory()) {
830 // Keep searching
831 current = merge->base_memory();
832 continue;
833 }
834 // Save the new memory state for the slice and fall through
835 // to exit.
836 result = new_st;
837 }
838 }
839 break;
840 }
841 if (result != NULL) {
842 st = result;
843 }
844 }
845
846
847 // Loop around twice in the case Load -> Initialize -> Store.
848 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
849 for (int trip = 0; trip <= 1; trip++) {
850
851 if (st->is_Store()) {
852 Node* st_adr = st->in(MemNode::Address);
853 if (!phase->eqv(st_adr, ld_adr)) {
854 // Try harder before giving up... Match raw and non-raw pointers.
855 intptr_t st_off = 0;
856 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
857 if (alloc == NULL) return NULL;
858 intptr_t ld_off = 0;
859 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
860 if (alloc != allo2) return NULL;
861 if (ld_off != st_off) return NULL;
862 // At this point we have proven something like this setup:
863 // A = Allocate(...)
864 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
865 // S = StoreQ(, AddP(, A.Parm , #Off), V)
866 // (Actually, we haven't yet proven the Q's are the same.)
867 // In other words, we are loading from a casted version of
868 // the same pointer-and-offset that we stored to.
869 // Thus, we are able to replace L by V.
870 }
871 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
872 if (store_Opcode() != st->Opcode())
873 return NULL;
874 return st->in(MemNode::ValueIn);
875 }
876
877 intptr_t offset = 0; // scratch
878
879 // A load from a freshly-created object always returns zero.
880 // (This can happen after LoadNode::Ideal resets the load's memory input
881 // to find_captured_store, which returned InitializeNode::zero_memory.)
882 if (st->is_Proj() && st->in(0)->is_Allocate() &&
883 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
884 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
885 // return a zero value for the load's basic type
886 // (This is one of the few places where a generic PhaseTransform
887 // can create new nodes. Think of it as lazily manifesting
888 // virtually pre-existing constants.)
889 return phase->zerocon(memory_type());
890 }
891
892 // A load from an initialization barrier can match a captured store.
893 if (st->is_Proj() && st->in(0)->is_Initialize()) {
894 InitializeNode* init = st->in(0)->as_Initialize();
895 AllocateNode* alloc = init->allocation();
896 if (alloc != NULL &&
897 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
898 // examine a captured store value
899 st = init->find_captured_store(offset, memory_size(), phase);
900 if (st != NULL)
901 continue; // take one more trip around
902 }
903 }
904
905 break;
906 }
907
908 return NULL;
909 }
910
911 //----------------------is_instance_field_load_with_local_phi------------------
912 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
913 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
914 in(MemNode::Address)->is_AddP() ) {
915 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
916 // Only instances.
917 if( t_oop != NULL && t_oop->is_instance_field() &&
918 t_oop->offset() != Type::OffsetBot &&
919 t_oop->offset() != Type::OffsetTop) {
920 return true;
921 }
922 }
923 return false;
924 }
925
926 //------------------------------Identity---------------------------------------
927 // Loads are identity if previous store is to same address
928 Node *LoadNode::Identity( PhaseTransform *phase ) {
929 // If the previous store-maker is the right kind of Store, and the store is
930 // to the same address, then we are equal to the value stored.
931 Node* mem = in(MemNode::Memory);
932 Node* value = can_see_stored_value(mem, phase);
933 if( value ) {
934 // byte, short & char stores truncate naturally.
935 // A load has to load the truncated value which requires
936 // some sort of masking operation and that requires an
937 // Ideal call instead of an Identity call.
938 if (memory_size() < BytesPerInt) {
939 // If the input to the store does not fit with the load's result type,
940 // it must be truncated via an Ideal call.
941 if (!phase->type(value)->higher_equal(phase->type(this)))
942 return this;
943 }
944 // (This works even when value is a Con, but LoadNode::Value
945 // usually runs first, producing the singleton type of the Con.)
946 return value;
947 }
948
949 // Search for an existing data phi which was generated before for the same
950 // instance's field to avoid infinite genertion of phis in a loop.
951 Node *region = mem->in(0);
952 if (is_instance_field_load_with_local_phi(region)) {
953 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
954 int this_index = phase->C->get_alias_index(addr_t);
955 int this_offset = addr_t->offset();
956 int this_id = addr_t->is_oopptr()->instance_id();
957 const Type* this_type = bottom_type();
958 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
959 Node* phi = region->fast_out(i);
960 if (phi->is_Phi() && phi != mem &&
961 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
962 return phi;
963 }
964 }
965 }
966
967 return this;
968 }
969
970
971 // Returns true if the AliasType refers to the field that holds the
972 // cached box array. Currently only handles the IntegerCache case.
973 static bool is_autobox_cache(Compile::AliasType* atp) {
974 if (atp != NULL && atp->field() != NULL) {
975 ciField* field = atp->field();
976 ciSymbol* klass = field->holder()->name();
977 if (field->name() == ciSymbol::cache_field_name() &&
978 field->holder()->uses_default_loader() &&
979 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
980 return true;
981 }
982 }
983 return false;
984 }
985
986 // Fetch the base value in the autobox array
987 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
988 if (atp != NULL && atp->field() != NULL) {
989 ciField* field = atp->field();
990 ciSymbol* klass = field->holder()->name();
991 if (field->name() == ciSymbol::cache_field_name() &&
992 field->holder()->uses_default_loader() &&
993 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
994 assert(field->is_constant(), "what?");
995 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
996 // Fetch the box object at the base of the array and get its value
997 ciInstance* box = array->obj_at(0)->as_instance();
998 ciInstanceKlass* ik = box->klass()->as_instance_klass();
999 if (ik->nof_nonstatic_fields() == 1) {
1000 // This should be true nonstatic_field_at requires calling
1001 // nof_nonstatic_fields so check it anyway
1002 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1003 cache_offset = c.as_int();
1004 }
1005 return true;
1006 }
1007 }
1008 return false;
1009 }
1010
1011 // Returns true if the AliasType refers to the value field of an
1012 // autobox object. Currently only handles Integer.
1013 static bool is_autobox_object(Compile::AliasType* atp) {
1014 if (atp != NULL && atp->field() != NULL) {
1015 ciField* field = atp->field();
1016 ciSymbol* klass = field->holder()->name();
1017 if (field->name() == ciSymbol::value_name() &&
1018 field->holder()->uses_default_loader() &&
1019 klass == ciSymbol::java_lang_Integer()) {
1020 return true;
1021 }
1022 }
1023 return false;
1024 }
1025
1026
1027 // We're loading from an object which has autobox behaviour.
1028 // If this object is result of a valueOf call we'll have a phi
1029 // merging a newly allocated object and a load from the cache.
1030 // We want to replace this load with the original incoming
1031 // argument to the valueOf call.
1032 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1033 Node* base = in(Address)->in(AddPNode::Base);
1034 if (base->is_Phi() && base->req() == 3) {
1035 AllocateNode* allocation = NULL;
1036 int allocation_index = -1;
1037 int load_index = -1;
1038 for (uint i = 1; i < base->req(); i++) {
1039 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1040 if (allocation != NULL) {
1041 allocation_index = i;
1042 load_index = 3 - allocation_index;
1043 break;
1044 }
1045 }
1046 LoadNode* load = NULL;
1047 if (allocation != NULL && base->in(load_index)->is_Load()) {
1048 load = base->in(load_index)->as_Load();
1049 }
1050 if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1051 // Push the loads from the phi that comes from valueOf up
1052 // through it to allow elimination of the loads and the recovery
1053 // of the original value.
1054 Node* mem_phi = in(Memory);
1055 Node* offset = in(Address)->in(AddPNode::Offset);
1056
1057 Node* in1 = clone();
1058 Node* in1_addr = in1->in(Address)->clone();
1059 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1060 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1061 in1_addr->set_req(AddPNode::Offset, offset);
1062 in1->set_req(0, base->in(allocation_index));
1063 in1->set_req(Address, in1_addr);
1064 in1->set_req(Memory, mem_phi->in(allocation_index));
1065
1066 Node* in2 = clone();
1067 Node* in2_addr = in2->in(Address)->clone();
1068 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1069 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1070 in2_addr->set_req(AddPNode::Offset, offset);
1071 in2->set_req(0, base->in(load_index));
1072 in2->set_req(Address, in2_addr);
1073 in2->set_req(Memory, mem_phi->in(load_index));
1074
1075 in1_addr = phase->transform(in1_addr);
1076 in1 = phase->transform(in1);
1077 in2_addr = phase->transform(in2_addr);
1078 in2 = phase->transform(in2);
1079
1080 PhiNode* result = PhiNode::make_blank(base->in(0), this);
1081 result->set_req(allocation_index, in1);
1082 result->set_req(load_index, in2);
1083 return result;
1084 }
1085 } else if (base->is_Load()) {
1086 // Eliminate the load of Integer.value for integers from the cache
1087 // array by deriving the value from the index into the array.
1088 // Capture the offset of the load and then reverse the computation.
1089 Node* load_base = base->in(Address)->in(AddPNode::Base);
1090 if (load_base != NULL) {
1091 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1092 intptr_t cache_offset;
1093 int shift = -1;
1094 Node* cache = NULL;
1095 if (is_autobox_cache(atp)) {
1096 shift = exact_log2(type2aelembytes(T_OBJECT));
1097 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1098 }
1099 if (cache != NULL && base->in(Address)->is_AddP()) {
1100 Node* elements[4];
1101 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1102 int cache_low;
1103 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1104 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1105 // Add up all the offsets making of the address of the load
1106 Node* result = elements[0];
1107 for (int i = 1; i < count; i++) {
1108 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1109 }
1110 // Remove the constant offset from the address and then
1111 // remove the scaling of the offset to recover the original index.
1112 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1113 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1114 // Peel the shift off directly but wrap it in a dummy node
1115 // since Ideal can't return existing nodes
1116 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1117 } else {
1118 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1119 }
1120 #ifdef _LP64
1121 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1122 #endif
1123 return result;
1124 }
1125 }
1126 }
1127 }
1128 return NULL;
1129 }
1130
1131 //------------------------------split_through_phi------------------------------
1132 // Split instance field load through Phi.
1133 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1134 Node* mem = in(MemNode::Memory);
1135 Node* address = in(MemNode::Address);
1136 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1137 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1138
1139 assert(mem->is_Phi() && (t_oop != NULL) &&
1140 t_oop->is_instance_field(), "invalide conditions");
1141
1142 Node *region = mem->in(0);
1143 if (region == NULL) {
1144 return NULL; // Wait stable graph
1145 }
1146 uint cnt = mem->req();
1147 for( uint i = 1; i < cnt; i++ ) {
1148 Node *in = mem->in(i);
1149 if( in == NULL ) {
1150 return NULL; // Wait stable graph
1151 }
1152 }
1153 // Check for loop invariant.
1154 if (cnt == 3) {
1155 for( uint i = 1; i < cnt; i++ ) {
1156 Node *in = mem->in(i);
1157 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1158 if (m == mem) {
1159 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1160 return this;
1161 }
1162 }
1163 }
1164 // Split through Phi (see original code in loopopts.cpp).
1165 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1166
1167 // Do nothing here if Identity will find a value
1168 // (to avoid infinite chain of value phis generation).
1169 if ( !phase->eqv(this, this->Identity(phase)) )
1170 return NULL;
1171
1172 // Skip the split if the region dominates some control edge of the address.
1173 if (cnt == 3 && !MemNode::all_controls_dominate(address, region))
1174 return NULL;
1175
1176 const Type* this_type = this->bottom_type();
1177 int this_index = phase->C->get_alias_index(addr_t);
1178 int this_offset = addr_t->offset();
1179 int this_iid = addr_t->is_oopptr()->instance_id();
1180 int wins = 0;
1181 PhaseIterGVN *igvn = phase->is_IterGVN();
1182 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1183 for( uint i = 1; i < region->req(); i++ ) {
1184 Node *x;
1185 Node* the_clone = NULL;
1186 if( region->in(i) == phase->C->top() ) {
1187 x = phase->C->top(); // Dead path? Use a dead data op
1188 } else {
1189 x = this->clone(); // Else clone up the data op
1190 the_clone = x; // Remember for possible deletion.
1191 // Alter data node to use pre-phi inputs
1192 if( this->in(0) == region ) {
1193 x->set_req( 0, region->in(i) );
1194 } else {
1195 x->set_req( 0, NULL );
1196 }
1197 for( uint j = 1; j < this->req(); j++ ) {
1198 Node *in = this->in(j);
1199 if( in->is_Phi() && in->in(0) == region )
1200 x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
1201 }
1202 }
1203 // Check for a 'win' on some paths
1204 const Type *t = x->Value(igvn);
1205
1206 bool singleton = t->singleton();
1207
1208 // See comments in PhaseIdealLoop::split_thru_phi().
1209 if( singleton && t == Type::TOP ) {
1210 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1211 }
1212
1213 if( singleton ) {
1214 wins++;
1215 x = igvn->makecon(t);
1216 } else {
1217 // We now call Identity to try to simplify the cloned node.
1218 // Note that some Identity methods call phase->type(this).
1219 // Make sure that the type array is big enough for
1220 // our new node, even though we may throw the node away.
1221 // (This tweaking with igvn only works because x is a new node.)
1222 igvn->set_type(x, t);
1223 Node *y = x->Identity(igvn);
1224 if( y != x ) {
1225 wins++;
1226 x = y;
1227 } else {
1228 y = igvn->hash_find(x);
1229 if( y ) {
1230 wins++;
1231 x = y;
1232 } else {
1233 // Else x is a new node we are keeping
1234 // We do not need register_new_node_with_optimizer
1235 // because set_type has already been called.
1236 igvn->_worklist.push(x);
1237 }
1238 }
1239 }
1240 if (x != the_clone && the_clone != NULL)
1241 igvn->remove_dead_node(the_clone);
1242 phi->set_req(i, x);
1243 }
1244 if( wins > 0 ) {
1245 // Record Phi
1246 igvn->register_new_node_with_optimizer(phi);
1247 return phi;
1248 }
1249 igvn->remove_dead_node(phi);
1250 return NULL;
1251 }
1252
1253 //------------------------------Ideal------------------------------------------
1254 // If the load is from Field memory and the pointer is non-null, we can
1255 // zero out the control input.
1256 // If the offset is constant and the base is an object allocation,
1257 // try to hook me up to the exact initializing store.
1258 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1259 Node* p = MemNode::Ideal_common(phase, can_reshape);
1260 if (p) return (p == NodeSentinel) ? NULL : p;
1261
1262 Node* ctrl = in(MemNode::Control);
1263 Node* address = in(MemNode::Address);
1264
1265 // Skip up past a SafePoint control. Cannot do this for Stores because
1266 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1267 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1268 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1269 ctrl = ctrl->in(0);
1270 set_req(MemNode::Control,ctrl);
1271 }
1272
1273 // Check for useless control edge in some common special cases
1274 if (in(MemNode::Control) != NULL) {
1275 intptr_t ignore = 0;
1276 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1277 if (base != NULL
1278 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1279 && all_controls_dominate(base, phase->C->start())) {
1280 // A method-invariant, non-null address (constant or 'this' argument).
1281 set_req(MemNode::Control, NULL);
1282 }
1283 }
1284
1285 if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) {
1286 Node* base = in(Address)->in(AddPNode::Base);
1287 if (base != NULL) {
1288 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1289 if (is_autobox_object(atp)) {
1290 Node* result = eliminate_autobox(phase);
1291 if (result != NULL) return result;
1292 }
1293 }
1294 }
1295
1296 Node* mem = in(MemNode::Memory);
1297 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1298
1299 if (addr_t != NULL) {
1300 // try to optimize our memory input
1301 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1302 if (opt_mem != mem) {
1303 set_req(MemNode::Memory, opt_mem);
1304 return this;
1305 }
1306 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1307 if (can_reshape && opt_mem->is_Phi() &&
1308 (t_oop != NULL) && t_oop->is_instance_field()) {
1309 // Split instance field load through Phi.
1310 Node* result = split_through_phi(phase);
1311 if (result != NULL) return result;
1312 }
1313 }
1314
1315 // Check for prior store with a different base or offset; make Load
1316 // independent. Skip through any number of them. Bail out if the stores
1317 // are in an endless dead cycle and report no progress. This is a key
1318 // transform for Reflection. However, if after skipping through the Stores
1319 // we can't then fold up against a prior store do NOT do the transform as
1320 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1321 // array memory alive twice: once for the hoisted Load and again after the
1322 // bypassed Store. This situation only works if EVERYBODY who does
1323 // anti-dependence work knows how to bypass. I.e. we need all
1324 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1325 // the alias index stuff. So instead, peek through Stores and IFF we can
1326 // fold up, do so.
1327 Node* prev_mem = find_previous_store(phase);
1328 // Steps (a), (b): Walk past independent stores to find an exact match.
1329 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1330 // (c) See if we can fold up on the spot, but don't fold up here.
1331 // Fold-up might require truncation (for LoadB/LoadS/LoadC) or
1332 // just return a prior value, which is done by Identity calls.
1333 if (can_see_stored_value(prev_mem, phase)) {
1334 // Make ready for step (d):
1335 set_req(MemNode::Memory, prev_mem);
1336 return this;
1337 }
1338 }
1339
1340 return NULL; // No further progress
1341 }
1342
1343 // Helper to recognize certain Klass fields which are invariant across
1344 // some group of array types (e.g., int[] or all T[] where T < Object).
1345 const Type*
1346 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1347 ciKlass* klass) const {
1348 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1349 // The field is Klass::_modifier_flags. Return its (constant) value.
1350 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1351 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1352 return TypeInt::make(klass->modifier_flags());
1353 }
1354 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1355 // The field is Klass::_access_flags. Return its (constant) value.
1356 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1357 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1358 return TypeInt::make(klass->access_flags());
1359 }
1360 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1361 // The field is Klass::_layout_helper. Return its constant value if known.
1362 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1363 return TypeInt::make(klass->layout_helper());
1364 }
1365
1366 // No match.
1367 return NULL;
1368 }
1369
1370 //------------------------------Value-----------------------------------------
1371 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1372 // Either input is TOP ==> the result is TOP
1373 Node* mem = in(MemNode::Memory);
1374 const Type *t1 = phase->type(mem);
1375 if (t1 == Type::TOP) return Type::TOP;
1376 Node* adr = in(MemNode::Address);
1377 const TypePtr* tp = phase->type(adr)->isa_ptr();
1378 if (tp == NULL || tp->empty()) return Type::TOP;
1379 int off = tp->offset();
1380 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1381
1382 // Try to guess loaded type from pointer type
1383 if (tp->base() == Type::AryPtr) {
1384 const Type *t = tp->is_aryptr()->elem();
1385 // Don't do this for integer types. There is only potential profit if
1386 // the element type t is lower than _type; that is, for int types, if _type is
1387 // more restrictive than t. This only happens here if one is short and the other
1388 // char (both 16 bits), and in those cases we've made an intentional decision
1389 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1390 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1391 //
1392 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1393 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1394 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1395 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1396 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1397 // In fact, that could have been the original type of p1, and p1 could have
1398 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1399 // expression (LShiftL quux 3) independently optimized to the constant 8.
1400 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1401 && Opcode() != Op_LoadKlass) {
1402 // t might actually be lower than _type, if _type is a unique
1403 // concrete subclass of abstract class t.
1404 // Make sure the reference is not into the header, by comparing
1405 // the offset against the offset of the start of the array's data.
1406 // Different array types begin at slightly different offsets (12 vs. 16).
1407 // We choose T_BYTE as an example base type that is least restrictive
1408 // as to alignment, which will therefore produce the smallest
1409 // possible base offset.
1410 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1411 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1412 const Type* jt = t->join(_type);
1413 // In any case, do not allow the join, per se, to empty out the type.
1414 if (jt->empty() && !t->empty()) {
1415 // This can happen if a interface-typed array narrows to a class type.
1416 jt = _type;
1417 }
1418
1419 if (EliminateAutoBox) {
1420 // The pointers in the autobox arrays are always non-null
1421 Node* base = in(Address)->in(AddPNode::Base);
1422 if (base != NULL) {
1423 Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
1424 if (is_autobox_cache(atp)) {
1425 return jt->join(TypePtr::NOTNULL)->is_ptr();
1426 }
1427 }
1428 }
1429 return jt;
1430 }
1431 }
1432 } else if (tp->base() == Type::InstPtr) {
1433 assert( off != Type::OffsetBot ||
1434 // arrays can be cast to Objects
1435 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1436 // unsafe field access may not have a constant offset
1437 phase->C->has_unsafe_access(),
1438 "Field accesses must be precise" );
1439 // For oop loads, we expect the _type to be precise
1440 } else if (tp->base() == Type::KlassPtr) {
1441 assert( off != Type::OffsetBot ||
1442 // arrays can be cast to Objects
1443 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1444 // also allow array-loading from the primary supertype
1445 // array during subtype checks
1446 Opcode() == Op_LoadKlass,
1447 "Field accesses must be precise" );
1448 // For klass/static loads, we expect the _type to be precise
1449 }
1450
1451 const TypeKlassPtr *tkls = tp->isa_klassptr();
1452 if (tkls != NULL && !StressReflectiveCode) {
1453 ciKlass* klass = tkls->klass();
1454 if (klass->is_loaded() && tkls->klass_is_exact()) {
1455 // We are loading a field from a Klass metaobject whose identity
1456 // is known at compile time (the type is "exact" or "precise").
1457 // Check for fields we know are maintained as constants by the VM.
1458 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1459 // The field is Klass::_super_check_offset. Return its (constant) value.
1460 // (Folds up type checking code.)
1461 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1462 return TypeInt::make(klass->super_check_offset());
1463 }
1464 // Compute index into primary_supers array
1465 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1466 // Check for overflowing; use unsigned compare to handle the negative case.
1467 if( depth < ciKlass::primary_super_limit() ) {
1468 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1469 // (Folds up type checking code.)
1470 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1471 ciKlass *ss = klass->super_of_depth(depth);
1472 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1473 }
1474 const Type* aift = load_array_final_field(tkls, klass);
1475 if (aift != NULL) return aift;
1476 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1477 && klass->is_array_klass()) {
1478 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1479 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1480 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1481 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1482 }
1483 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1484 // The field is Klass::_java_mirror. Return its (constant) value.
1485 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1486 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1487 return TypeInstPtr::make(klass->java_mirror());
1488 }
1489 }
1490
1491 // We can still check if we are loading from the primary_supers array at a
1492 // shallow enough depth. Even though the klass is not exact, entries less
1493 // than or equal to its super depth are correct.
1494 if (klass->is_loaded() ) {
1495 ciType *inner = klass->klass();
1496 while( inner->is_obj_array_klass() )
1497 inner = inner->as_obj_array_klass()->base_element_type();
1498 if( inner->is_instance_klass() &&
1499 !inner->as_instance_klass()->flags().is_interface() ) {
1500 // Compute index into primary_supers array
1501 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1502 // Check for overflowing; use unsigned compare to handle the negative case.
1503 if( depth < ciKlass::primary_super_limit() &&
1504 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1505 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1506 // (Folds up type checking code.)
1507 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1508 ciKlass *ss = klass->super_of_depth(depth);
1509 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1510 }
1511 }
1512 }
1513
1514 // If the type is enough to determine that the thing is not an array,
1515 // we can give the layout_helper a positive interval type.
1516 // This will help short-circuit some reflective code.
1517 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1518 && !klass->is_array_klass() // not directly typed as an array
1519 && !klass->is_interface() // specifically not Serializable & Cloneable
1520 && !klass->is_java_lang_Object() // not the supertype of all T[]
1521 ) {
1522 // Note: When interfaces are reliable, we can narrow the interface
1523 // test to (klass != Serializable && klass != Cloneable).
1524 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1525 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1526 // The key property of this type is that it folds up tests
1527 // for array-ness, since it proves that the layout_helper is positive.
1528 // Thus, a generic value like the basic object layout helper works fine.
1529 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1530 }
1531 }
1532
1533 // If we are loading from a freshly-allocated object, produce a zero,
1534 // if the load is provably beyond the header of the object.
1535 // (Also allow a variable load from a fresh array to produce zero.)
1536 if (ReduceFieldZeroing) {
1537 Node* value = can_see_stored_value(mem,phase);
1538 if (value != NULL && value->is_Con())
1539 return value->bottom_type();
1540 }
1541
1542 const TypeOopPtr *tinst = tp->isa_oopptr();
1543 if (tinst != NULL && tinst->is_instance_field()) {
1544 // If we have an instance type and our memory input is the
1545 // programs's initial memory state, there is no matching store,
1546 // so just return a zero of the appropriate type
1547 Node *mem = in(MemNode::Memory);
1548 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1549 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1550 return Type::get_zero_type(_type->basic_type());
1551 }
1552 }
1553 return _type;
1554 }
1555
1556 //------------------------------match_edge-------------------------------------
1557 // Do we Match on this edge index or not? Match only the address.
1558 uint LoadNode::match_edge(uint idx) const {
1559 return idx == MemNode::Address;
1560 }
1561
1562 //--------------------------LoadBNode::Ideal--------------------------------------
1563 //
1564 // If the previous store is to the same address as this load,
1565 // and the value stored was larger than a byte, replace this load
1566 // with the value stored truncated to a byte. If no truncation is
1567 // needed, the replacement is done in LoadNode::Identity().
1568 //
1569 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1570 Node* mem = in(MemNode::Memory);
1571 Node* value = can_see_stored_value(mem,phase);
1572 if( value && !phase->type(value)->higher_equal( _type ) ) {
1573 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1574 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1575 }
1576 // Identity call will handle the case where truncation is not needed.
1577 return LoadNode::Ideal(phase, can_reshape);
1578 }
1579
1580 //--------------------------LoadCNode::Ideal--------------------------------------
1581 //
1582 // If the previous store is to the same address as this load,
1583 // and the value stored was larger than a char, replace this load
1584 // with the value stored truncated to a char. If no truncation is
1585 // needed, the replacement is done in LoadNode::Identity().
1586 //
1587 Node *LoadCNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1588 Node* mem = in(MemNode::Memory);
1589 Node* value = can_see_stored_value(mem,phase);
1590 if( value && !phase->type(value)->higher_equal( _type ) )
1591 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1592 // Identity call will handle the case where truncation is not needed.
1593 return LoadNode::Ideal(phase, can_reshape);
1594 }
1595
1596 //--------------------------LoadSNode::Ideal--------------------------------------
1597 //
1598 // If the previous store is to the same address as this load,
1599 // and the value stored was larger than a short, replace this load
1600 // with the value stored truncated to a short. If no truncation is
1601 // needed, the replacement is done in LoadNode::Identity().
1602 //
1603 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1604 Node* mem = in(MemNode::Memory);
1605 Node* value = can_see_stored_value(mem,phase);
1606 if( value && !phase->type(value)->higher_equal( _type ) ) {
1607 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1608 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1609 }
1610 // Identity call will handle the case where truncation is not needed.
1611 return LoadNode::Ideal(phase, can_reshape);
1612 }
1613
1614 //=============================================================================
1615 //----------------------------LoadKlassNode::make------------------------------
1616 // Polymorphic factory method:
1617 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1618 Compile* C = gvn.C;
1619 Node *ctl = NULL;
1620 // sanity check the alias category against the created node type
1621 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1622 assert(adr_type != NULL, "expecting TypeOopPtr");
1623 #ifdef _LP64
1624 if (adr_type->is_ptr_to_narrowoop()) {
1625 const TypeNarrowOop* narrowtype = tk->is_oopptr()->make_narrowoop();
1626 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, narrowtype));
1627 return DecodeNNode::decode(&gvn, load_klass);
1628 }
1629 #endif
1630 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1631 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1632 }
1633
1634 //------------------------------Value------------------------------------------
1635 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1636 return klass_value_common(phase);
1637 }
1638
1639 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1640 // Either input is TOP ==> the result is TOP
1641 const Type *t1 = phase->type( in(MemNode::Memory) );
1642 if (t1 == Type::TOP) return Type::TOP;
1643 Node *adr = in(MemNode::Address);
1644 const Type *t2 = phase->type( adr );
1645 if (t2 == Type::TOP) return Type::TOP;
1646 const TypePtr *tp = t2->is_ptr();
1647 if (TypePtr::above_centerline(tp->ptr()) ||
1648 tp->ptr() == TypePtr::Null) return Type::TOP;
1649
1650 // Return a more precise klass, if possible
1651 const TypeInstPtr *tinst = tp->isa_instptr();
1652 if (tinst != NULL) {
1653 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1654 int offset = tinst->offset();
1655 if (ik == phase->C->env()->Class_klass()
1656 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1657 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1658 // We are loading a special hidden field from a Class mirror object,
1659 // the field which points to the VM's Klass metaobject.
1660 ciType* t = tinst->java_mirror_type();
1661 // java_mirror_type returns non-null for compile-time Class constants.
1662 if (t != NULL) {
1663 // constant oop => constant klass
1664 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1665 return TypeKlassPtr::make(ciArrayKlass::make(t));
1666 }
1667 if (!t->is_klass()) {
1668 // a primitive Class (e.g., int.class) has NULL for a klass field
1669 return TypePtr::NULL_PTR;
1670 }
1671 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1672 return TypeKlassPtr::make(t->as_klass());
1673 }
1674 // non-constant mirror, so we can't tell what's going on
1675 }
1676 if( !ik->is_loaded() )
1677 return _type; // Bail out if not loaded
1678 if (offset == oopDesc::klass_offset_in_bytes()) {
1679 if (tinst->klass_is_exact()) {
1680 return TypeKlassPtr::make(ik);
1681 }
1682 // See if we can become precise: no subklasses and no interface
1683 // (Note: We need to support verified interfaces.)
1684 if (!ik->is_interface() && !ik->has_subklass()) {
1685 //assert(!UseExactTypes, "this code should be useless with exact types");
1686 // Add a dependence; if any subclass added we need to recompile
1687 if (!ik->is_final()) {
1688 // %%% should use stronger assert_unique_concrete_subtype instead
1689 phase->C->dependencies()->assert_leaf_type(ik);
1690 }
1691 // Return precise klass
1692 return TypeKlassPtr::make(ik);
1693 }
1694
1695 // Return root of possible klass
1696 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1697 }
1698 }
1699
1700 // Check for loading klass from an array
1701 const TypeAryPtr *tary = tp->isa_aryptr();
1702 if( tary != NULL ) {
1703 ciKlass *tary_klass = tary->klass();
1704 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1705 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1706 if (tary->klass_is_exact()) {
1707 return TypeKlassPtr::make(tary_klass);
1708 }
1709 ciArrayKlass *ak = tary->klass()->as_array_klass();
1710 // If the klass is an object array, we defer the question to the
1711 // array component klass.
1712 if( ak->is_obj_array_klass() ) {
1713 assert( ak->is_loaded(), "" );
1714 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1715 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1716 ciInstanceKlass* ik = base_k->as_instance_klass();
1717 // See if we can become precise: no subklasses and no interface
1718 if (!ik->is_interface() && !ik->has_subklass()) {
1719 //assert(!UseExactTypes, "this code should be useless with exact types");
1720 // Add a dependence; if any subclass added we need to recompile
1721 if (!ik->is_final()) {
1722 phase->C->dependencies()->assert_leaf_type(ik);
1723 }
1724 // Return precise array klass
1725 return TypeKlassPtr::make(ak);
1726 }
1727 }
1728 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1729 } else { // Found a type-array?
1730 //assert(!UseExactTypes, "this code should be useless with exact types");
1731 assert( ak->is_type_array_klass(), "" );
1732 return TypeKlassPtr::make(ak); // These are always precise
1733 }
1734 }
1735 }
1736
1737 // Check for loading klass from an array klass
1738 const TypeKlassPtr *tkls = tp->isa_klassptr();
1739 if (tkls != NULL && !StressReflectiveCode) {
1740 ciKlass* klass = tkls->klass();
1741 if( !klass->is_loaded() )
1742 return _type; // Bail out if not loaded
1743 if( klass->is_obj_array_klass() &&
1744 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1745 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1746 // // Always returning precise element type is incorrect,
1747 // // e.g., element type could be object and array may contain strings
1748 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1749
1750 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1751 // according to the element type's subclassing.
1752 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1753 }
1754 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1755 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1756 ciKlass* sup = klass->as_instance_klass()->super();
1757 // The field is Klass::_super. Return its (constant) value.
1758 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1759 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1760 }
1761 }
1762
1763 // Bailout case
1764 return LoadNode::Value(phase);
1765 }
1766
1767 //------------------------------Identity---------------------------------------
1768 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1769 // Also feed through the klass in Allocate(...klass...)._klass.
1770 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1771 return klass_identity_common(phase);
1772 }
1773
1774 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1775 Node* x = LoadNode::Identity(phase);
1776 if (x != this) return x;
1777
1778 // Take apart the address into an oop and and offset.
1779 // Return 'this' if we cannot.
1780 Node* adr = in(MemNode::Address);
1781 intptr_t offset = 0;
1782 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1783 if (base == NULL) return this;
1784 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1785 if (toop == NULL) return this;
1786
1787 // We can fetch the klass directly through an AllocateNode.
1788 // This works even if the klass is not constant (clone or newArray).
1789 if (offset == oopDesc::klass_offset_in_bytes()) {
1790 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1791 if (allocated_klass != NULL) {
1792 return allocated_klass;
1793 }
1794 }
1795
1796 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1797 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1798 // See inline_native_Class_query for occurrences of these patterns.
1799 // Java Example: x.getClass().isAssignableFrom(y)
1800 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1801 //
1802 // This improves reflective code, often making the Class
1803 // mirror go completely dead. (Current exception: Class
1804 // mirrors may appear in debug info, but we could clean them out by
1805 // introducing a new debug info operator for klassOop.java_mirror).
1806 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1807 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1808 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1809 // We are loading a special hidden field from a Class mirror,
1810 // the field which points to its Klass or arrayKlass metaobject.
1811 if (base->is_Load()) {
1812 Node* adr2 = base->in(MemNode::Address);
1813 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
1814 if (tkls != NULL && !tkls->empty()
1815 && (tkls->klass()->is_instance_klass() ||
1816 tkls->klass()->is_array_klass())
1817 && adr2->is_AddP()
1818 ) {
1819 int mirror_field = Klass::java_mirror_offset_in_bytes();
1820 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1821 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
1822 }
1823 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
1824 return adr2->in(AddPNode::Base);
1825 }
1826 }
1827 }
1828 }
1829
1830 return this;
1831 }
1832
1833
1834 //------------------------------Value------------------------------------------
1835 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
1836 const Type *t = klass_value_common(phase);
1837
1838 if (t == TypePtr::NULL_PTR) {
1839 return TypeNarrowOop::NULL_PTR;
1840 }
1841 if (t != Type::TOP && !t->isa_narrowoop()) {
1842 assert(t->is_oopptr(), "sanity");
1843 t = t->is_oopptr()->make_narrowoop();
1844 }
1845 return t;
1846 }
1847
1848 //------------------------------Identity---------------------------------------
1849 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
1850 // Also feed through the klass in Allocate(...klass...)._klass.
1851 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
1852 Node *x = klass_identity_common(phase);
1853
1854 const Type *t = phase->type( x );
1855 if( t == Type::TOP ) return x;
1856 if( t->isa_narrowoop()) return x;
1857
1858 return EncodePNode::encode(phase, x);
1859 }
1860
1861 //------------------------------Value-----------------------------------------
1862 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
1863 // Either input is TOP ==> the result is TOP
1864 const Type *t1 = phase->type( in(MemNode::Memory) );
1865 if( t1 == Type::TOP ) return Type::TOP;
1866 Node *adr = in(MemNode::Address);
1867 const Type *t2 = phase->type( adr );
1868 if( t2 == Type::TOP ) return Type::TOP;
1869 const TypePtr *tp = t2->is_ptr();
1870 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
1871 const TypeAryPtr *tap = tp->isa_aryptr();
1872 if( !tap ) return _type;
1873 return tap->size();
1874 }
1875
1876 //------------------------------Identity---------------------------------------
1877 // Feed through the length in AllocateArray(...length...)._length.
1878 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
1879 Node* x = LoadINode::Identity(phase);
1880 if (x != this) return x;
1881
1882 // Take apart the address into an oop and and offset.
1883 // Return 'this' if we cannot.
1884 Node* adr = in(MemNode::Address);
1885 intptr_t offset = 0;
1886 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1887 if (base == NULL) return this;
1888 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
1889 if (tary == NULL) return this;
1890
1891 // We can fetch the length directly through an AllocateArrayNode.
1892 // This works even if the length is not constant (clone or newArray).
1893 if (offset == arrayOopDesc::length_offset_in_bytes()) {
1894 Node* allocated_length = AllocateArrayNode::Ideal_length(base, phase);
1895 if (allocated_length != NULL) {
1896 return allocated_length;
1897 }
1898 }
1899
1900 return this;
1901
1902 }
1903 //=============================================================================
1904 //---------------------------StoreNode::make-----------------------------------
1905 // Polymorphic factory method:
1906 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
1907 Compile* C = gvn.C;
1908
1909 switch (bt) {
1910 case T_BOOLEAN:
1911 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
1912 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
1913 case T_CHAR:
1914 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
1915 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
1916 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
1917 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
1918 case T_ADDRESS:
1919 case T_OBJECT:
1920 #ifdef _LP64
1921 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
1922 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
1923 adr->bottom_type()->isa_rawptr())) {
1924 const TypePtr* type = val->bottom_type()->is_ptr();
1925 Node* cp = EncodePNode::encode(&gvn, val);
1926 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, cp);
1927 } else
1928 #endif
1929 {
1930 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
1931 }
1932 }
1933 ShouldNotReachHere();
1934 return (StoreNode*)NULL;
1935 }
1936
1937 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
1938 bool require_atomic = true;
1939 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
1940 }
1941
1942
1943 //--------------------------bottom_type----------------------------------------
1944 const Type *StoreNode::bottom_type() const {
1945 return Type::MEMORY;
1946 }
1947
1948 //------------------------------hash-------------------------------------------
1949 uint StoreNode::hash() const {
1950 // unroll addition of interesting fields
1951 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
1952
1953 // Since they are not commoned, do not hash them:
1954 return NO_HASH;
1955 }
1956
1957 //------------------------------Ideal------------------------------------------
1958 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
1959 // When a store immediately follows a relevant allocation/initialization,
1960 // try to capture it into the initialization, or hoist it above.
1961 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1962 Node* p = MemNode::Ideal_common(phase, can_reshape);
1963 if (p) return (p == NodeSentinel) ? NULL : p;
1964
1965 Node* mem = in(MemNode::Memory);
1966 Node* address = in(MemNode::Address);
1967
1968 // Back-to-back stores to same address? Fold em up.
1969 // Generally unsafe if I have intervening uses...
1970 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address)) {
1971 // Looking at a dead closed cycle of memory?
1972 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
1973
1974 assert(Opcode() == mem->Opcode() ||
1975 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
1976 "no mismatched stores, except on raw memory");
1977
1978 if (mem->outcnt() == 1 && // check for intervening uses
1979 mem->as_Store()->memory_size() <= this->memory_size()) {
1980 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
1981 // For example, 'mem' might be the final state at a conditional return.
1982 // Or, 'mem' might be used by some node which is live at the same time
1983 // 'this' is live, which might be unschedulable. So, require exactly
1984 // ONE user, the 'this' store, until such time as we clone 'mem' for
1985 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
1986 if (can_reshape) { // (%%% is this an anachronism?)
1987 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
1988 phase->is_IterGVN());
1989 } else {
1990 // It's OK to do this in the parser, since DU info is always accurate,
1991 // and the parser always refers to nodes via SafePointNode maps.
1992 set_req(MemNode::Memory, mem->in(MemNode::Memory));
1993 }
1994 return this;
1995 }
1996 }
1997
1998 // Capture an unaliased, unconditional, simple store into an initializer.
1999 // Or, if it is independent of the allocation, hoist it above the allocation.
2000 if (ReduceFieldZeroing && /*can_reshape &&*/
2001 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2002 InitializeNode* init = mem->in(0)->as_Initialize();
2003 intptr_t offset = init->can_capture_store(this, phase);
2004 if (offset > 0) {
2005 Node* moved = init->capture_store(this, offset, phase);
2006 // If the InitializeNode captured me, it made a raw copy of me,
2007 // and I need to disappear.
2008 if (moved != NULL) {
2009 // %%% hack to ensure that Ideal returns a new node:
2010 mem = MergeMemNode::make(phase->C, mem);
2011 return mem; // fold me away
2012 }
2013 }
2014 }
2015
2016 return NULL; // No further progress
2017 }
2018
2019 //------------------------------Value-----------------------------------------
2020 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2021 // Either input is TOP ==> the result is TOP
2022 const Type *t1 = phase->type( in(MemNode::Memory) );
2023 if( t1 == Type::TOP ) return Type::TOP;
2024 const Type *t2 = phase->type( in(MemNode::Address) );
2025 if( t2 == Type::TOP ) return Type::TOP;
2026 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2027 if( t3 == Type::TOP ) return Type::TOP;
2028 return Type::MEMORY;
2029 }
2030
2031 //------------------------------Identity---------------------------------------
2032 // Remove redundant stores:
2033 // Store(m, p, Load(m, p)) changes to m.
2034 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2035 Node *StoreNode::Identity( PhaseTransform *phase ) {
2036 Node* mem = in(MemNode::Memory);
2037 Node* adr = in(MemNode::Address);
2038 Node* val = in(MemNode::ValueIn);
2039
2040 // Load then Store? Then the Store is useless
2041 if (val->is_Load() &&
2042 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2043 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2044 val->as_Load()->store_Opcode() == Opcode()) {
2045 return mem;
2046 }
2047
2048 // Two stores in a row of the same value?
2049 if (mem->is_Store() &&
2050 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2051 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2052 mem->Opcode() == Opcode()) {
2053 return mem;
2054 }
2055
2056 // Store of zero anywhere into a freshly-allocated object?
2057 // Then the store is useless.
2058 // (It must already have been captured by the InitializeNode.)
2059 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2060 // a newly allocated object is already all-zeroes everywhere
2061 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2062 return mem;
2063 }
2064
2065 // the store may also apply to zero-bits in an earlier object
2066 Node* prev_mem = find_previous_store(phase);
2067 // Steps (a), (b): Walk past independent stores to find an exact match.
2068 if (prev_mem != NULL) {
2069 Node* prev_val = can_see_stored_value(prev_mem, phase);
2070 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2071 // prev_val and val might differ by a cast; it would be good
2072 // to keep the more informative of the two.
2073 return mem;
2074 }
2075 }
2076 }
2077
2078 return this;
2079 }
2080
2081 //------------------------------match_edge-------------------------------------
2082 // Do we Match on this edge index or not? Match only memory & value
2083 uint StoreNode::match_edge(uint idx) const {
2084 return idx == MemNode::Address || idx == MemNode::ValueIn;
2085 }
2086
2087 //------------------------------cmp--------------------------------------------
2088 // Do not common stores up together. They generally have to be split
2089 // back up anyways, so do not bother.
2090 uint StoreNode::cmp( const Node &n ) const {
2091 return (&n == this); // Always fail except on self
2092 }
2093
2094 //------------------------------Ideal_masked_input-----------------------------
2095 // Check for a useless mask before a partial-word store
2096 // (StoreB ... (AndI valIn conIa) )
2097 // If (conIa & mask == mask) this simplifies to
2098 // (StoreB ... (valIn) )
2099 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2100 Node *val = in(MemNode::ValueIn);
2101 if( val->Opcode() == Op_AndI ) {
2102 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2103 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2104 set_req(MemNode::ValueIn, val->in(1));
2105 return this;
2106 }
2107 }
2108 return NULL;
2109 }
2110
2111
2112 //------------------------------Ideal_sign_extended_input----------------------
2113 // Check for useless sign-extension before a partial-word store
2114 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2115 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2116 // (StoreB ... (valIn) )
2117 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2118 Node *val = in(MemNode::ValueIn);
2119 if( val->Opcode() == Op_RShiftI ) {
2120 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2121 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2122 Node *shl = val->in(1);
2123 if( shl->Opcode() == Op_LShiftI ) {
2124 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2125 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2126 set_req(MemNode::ValueIn, shl->in(1));
2127 return this;
2128 }
2129 }
2130 }
2131 }
2132 return NULL;
2133 }
2134
2135 //------------------------------value_never_loaded-----------------------------------
2136 // Determine whether there are any possible loads of the value stored.
2137 // For simplicity, we actually check if there are any loads from the
2138 // address stored to, not just for loads of the value stored by this node.
2139 //
2140 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2141 Node *adr = in(Address);
2142 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2143 if (adr_oop == NULL)
2144 return false;
2145 if (!adr_oop->is_instance_field())
2146 return false; // if not a distinct instance, there may be aliases of the address
2147 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2148 Node *use = adr->fast_out(i);
2149 int opc = use->Opcode();
2150 if (use->is_Load() || use->is_LoadStore()) {
2151 return false;
2152 }
2153 }
2154 return true;
2155 }
2156
2157 //=============================================================================
2158 //------------------------------Ideal------------------------------------------
2159 // If the store is from an AND mask that leaves the low bits untouched, then
2160 // we can skip the AND operation. If the store is from a sign-extension
2161 // (a left shift, then right shift) we can skip both.
2162 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2163 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2164 if( progress != NULL ) return progress;
2165
2166 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2167 if( progress != NULL ) return progress;
2168
2169 // Finally check the default case
2170 return StoreNode::Ideal(phase, can_reshape);
2171 }
2172
2173 //=============================================================================
2174 //------------------------------Ideal------------------------------------------
2175 // If the store is from an AND mask that leaves the low bits untouched, then
2176 // we can skip the AND operation
2177 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2178 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2179 if( progress != NULL ) return progress;
2180
2181 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2182 if( progress != NULL ) return progress;
2183
2184 // Finally check the default case
2185 return StoreNode::Ideal(phase, can_reshape);
2186 }
2187
2188 //=============================================================================
2189 //------------------------------Identity---------------------------------------
2190 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2191 // No need to card mark when storing a null ptr
2192 Node* my_store = in(MemNode::OopStore);
2193 if (my_store->is_Store()) {
2194 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2195 if( t1 == TypePtr::NULL_PTR ) {
2196 return in(MemNode::Memory);
2197 }
2198 }
2199 return this;
2200 }
2201
2202 //------------------------------Value-----------------------------------------
2203 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2204 // Either input is TOP ==> the result is TOP
2205 const Type *t = phase->type( in(MemNode::Memory) );
2206 if( t == Type::TOP ) return Type::TOP;
2207 t = phase->type( in(MemNode::Address) );
2208 if( t == Type::TOP ) return Type::TOP;
2209 t = phase->type( in(MemNode::ValueIn) );
2210 if( t == Type::TOP ) return Type::TOP;
2211 // If extra input is TOP ==> the result is TOP
2212 t = phase->type( in(MemNode::OopStore) );
2213 if( t == Type::TOP ) return Type::TOP;
2214
2215 return StoreNode::Value( phase );
2216 }
2217
2218
2219 //=============================================================================
2220 //----------------------------------SCMemProjNode------------------------------
2221 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2222 {
2223 return bottom_type();
2224 }
2225
2226 //=============================================================================
2227 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2228 init_req(MemNode::Control, c );
2229 init_req(MemNode::Memory , mem);
2230 init_req(MemNode::Address, adr);
2231 init_req(MemNode::ValueIn, val);
2232 init_req( ExpectedIn, ex );
2233 init_class_id(Class_LoadStore);
2234
2235 }
2236
2237 //=============================================================================
2238 //-------------------------------adr_type--------------------------------------
2239 // Do we Match on this edge index or not? Do not match memory
2240 const TypePtr* ClearArrayNode::adr_type() const {
2241 Node *adr = in(3);
2242 return MemNode::calculate_adr_type(adr->bottom_type());
2243 }
2244
2245 //------------------------------match_edge-------------------------------------
2246 // Do we Match on this edge index or not? Do not match memory
2247 uint ClearArrayNode::match_edge(uint idx) const {
2248 return idx > 1;
2249 }
2250
2251 //------------------------------Identity---------------------------------------
2252 // Clearing a zero length array does nothing
2253 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2254 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2255 }
2256
2257 //------------------------------Idealize---------------------------------------
2258 // Clearing a short array is faster with stores
2259 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2260 const int unit = BytesPerLong;
2261 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2262 if (!t) return NULL;
2263 if (!t->is_con()) return NULL;
2264 intptr_t raw_count = t->get_con();
2265 intptr_t size = raw_count;
2266 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2267 // Clearing nothing uses the Identity call.
2268 // Negative clears are possible on dead ClearArrays
2269 // (see jck test stmt114.stmt11402.val).
2270 if (size <= 0 || size % unit != 0) return NULL;
2271 intptr_t count = size / unit;
2272 // Length too long; use fast hardware clear
2273 if (size > Matcher::init_array_short_size) return NULL;
2274 Node *mem = in(1);
2275 if( phase->type(mem)==Type::TOP ) return NULL;
2276 Node *adr = in(3);
2277 const Type* at = phase->type(adr);
2278 if( at==Type::TOP ) return NULL;
2279 const TypePtr* atp = at->isa_ptr();
2280 // adjust atp to be the correct array element address type
2281 if (atp == NULL) atp = TypePtr::BOTTOM;
2282 else atp = atp->add_offset(Type::OffsetBot);
2283 // Get base for derived pointer purposes
2284 if( adr->Opcode() != Op_AddP ) Unimplemented();
2285 Node *base = adr->in(1);
2286
2287 Node *zero = phase->makecon(TypeLong::ZERO);
2288 Node *off = phase->MakeConX(BytesPerLong);
2289 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2290 count--;
2291 while( count-- ) {
2292 mem = phase->transform(mem);
2293 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2294 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2295 }
2296 return mem;
2297 }
2298
2299 //----------------------------clear_memory-------------------------------------
2300 // Generate code to initialize object storage to zero.
2301 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2302 intptr_t start_offset,
2303 Node* end_offset,
2304 PhaseGVN* phase) {
2305 Compile* C = phase->C;
2306 intptr_t offset = start_offset;
2307
2308 int unit = BytesPerLong;
2309 if ((offset % unit) != 0) {
2310 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2311 adr = phase->transform(adr);
2312 const TypePtr* atp = TypeRawPtr::BOTTOM;
2313 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2314 mem = phase->transform(mem);
2315 offset += BytesPerInt;
2316 }
2317 assert((offset % unit) == 0, "");
2318
2319 // Initialize the remaining stuff, if any, with a ClearArray.
2320 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2321 }
2322
2323 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2324 Node* start_offset,
2325 Node* end_offset,
2326 PhaseGVN* phase) {
2327 if (start_offset == end_offset) {
2328 // nothing to do
2329 return mem;
2330 }
2331
2332 Compile* C = phase->C;
2333 int unit = BytesPerLong;
2334 Node* zbase = start_offset;
2335 Node* zend = end_offset;
2336
2337 // Scale to the unit required by the CPU:
2338 if (!Matcher::init_array_count_is_in_bytes) {
2339 Node* shift = phase->intcon(exact_log2(unit));
2340 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2341 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2342 }
2343
2344 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2345 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2346
2347 // Bulk clear double-words
2348 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2349 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2350 return phase->transform(mem);
2351 }
2352
2353 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2354 intptr_t start_offset,
2355 intptr_t end_offset,
2356 PhaseGVN* phase) {
2357 if (start_offset == end_offset) {
2358 // nothing to do
2359 return mem;
2360 }
2361
2362 Compile* C = phase->C;
2363 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2364 intptr_t done_offset = end_offset;
2365 if ((done_offset % BytesPerLong) != 0) {
2366 done_offset -= BytesPerInt;
2367 }
2368 if (done_offset > start_offset) {
2369 mem = clear_memory(ctl, mem, dest,
2370 start_offset, phase->MakeConX(done_offset), phase);
2371 }
2372 if (done_offset < end_offset) { // emit the final 32-bit store
2373 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2374 adr = phase->transform(adr);
2375 const TypePtr* atp = TypeRawPtr::BOTTOM;
2376 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2377 mem = phase->transform(mem);
2378 done_offset += BytesPerInt;
2379 }
2380 assert(done_offset == end_offset, "");
2381 return mem;
2382 }
2383
2384 //=============================================================================
2385 // Do we match on this edge? No memory edges
2386 uint StrCompNode::match_edge(uint idx) const {
2387 return idx == 5 || idx == 6;
2388 }
2389
2390 //------------------------------Ideal------------------------------------------
2391 // Return a node which is more "ideal" than the current node. Strip out
2392 // control copies
2393 Node *StrCompNode::Ideal(PhaseGVN *phase, bool can_reshape){
2394 return remove_dead_region(phase, can_reshape) ? this : NULL;
2395 }
2396
2397 //------------------------------Ideal------------------------------------------
2398 // Return a node which is more "ideal" than the current node. Strip out
2399 // control copies
2400 Node *AryEqNode::Ideal(PhaseGVN *phase, bool can_reshape){
2401 return remove_dead_region(phase, can_reshape) ? this : NULL;
2402 }
2403
2404
2405 //=============================================================================
2406 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2407 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2408 _adr_type(C->get_adr_type(alias_idx))
2409 {
2410 init_class_id(Class_MemBar);
2411 Node* top = C->top();
2412 init_req(TypeFunc::I_O,top);
2413 init_req(TypeFunc::FramePtr,top);
2414 init_req(TypeFunc::ReturnAdr,top);
2415 if (precedent != NULL)
2416 init_req(TypeFunc::Parms, precedent);
2417 }
2418
2419 //------------------------------cmp--------------------------------------------
2420 uint MemBarNode::hash() const { return NO_HASH; }
2421 uint MemBarNode::cmp( const Node &n ) const {
2422 return (&n == this); // Always fail except on self
2423 }
2424
2425 //------------------------------make-------------------------------------------
2426 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2427 int len = Precedent + (pn == NULL? 0: 1);
2428 switch (opcode) {
2429 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2430 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2431 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2432 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2433 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2434 default: ShouldNotReachHere(); return NULL;
2435 }
2436 }
2437
2438 //------------------------------Ideal------------------------------------------
2439 // Return a node which is more "ideal" than the current node. Strip out
2440 // control copies
2441 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2442 if (remove_dead_region(phase, can_reshape)) return this;
2443 return NULL;
2444 }
2445
2446 //------------------------------Value------------------------------------------
2447 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2448 if( !in(0) ) return Type::TOP;
2449 if( phase->type(in(0)) == Type::TOP )
2450 return Type::TOP;
2451 return TypeTuple::MEMBAR;
2452 }
2453
2454 //------------------------------match------------------------------------------
2455 // Construct projections for memory.
2456 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2457 switch (proj->_con) {
2458 case TypeFunc::Control:
2459 case TypeFunc::Memory:
2460 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2461 }
2462 ShouldNotReachHere();
2463 return NULL;
2464 }
2465
2466 //===========================InitializeNode====================================
2467 // SUMMARY:
2468 // This node acts as a memory barrier on raw memory, after some raw stores.
2469 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2470 // The Initialize can 'capture' suitably constrained stores as raw inits.
2471 // It can coalesce related raw stores into larger units (called 'tiles').
2472 // It can avoid zeroing new storage for memory units which have raw inits.
2473 // At macro-expansion, it is marked 'complete', and does not optimize further.
2474 //
2475 // EXAMPLE:
2476 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2477 // ctl = incoming control; mem* = incoming memory
2478 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2479 // First allocate uninitialized memory and fill in the header:
2480 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2481 // ctl := alloc.Control; mem* := alloc.Memory*
2482 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2483 // Then initialize to zero the non-header parts of the raw memory block:
2484 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2485 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2486 // After the initialize node executes, the object is ready for service:
2487 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2488 // Suppose its body is immediately initialized as {1,2}:
2489 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2490 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2491 // mem.SLICE(#short[*]) := store2
2492 //
2493 // DETAILS:
2494 // An InitializeNode collects and isolates object initialization after
2495 // an AllocateNode and before the next possible safepoint. As a
2496 // memory barrier (MemBarNode), it keeps critical stores from drifting
2497 // down past any safepoint or any publication of the allocation.
2498 // Before this barrier, a newly-allocated object may have uninitialized bits.
2499 // After this barrier, it may be treated as a real oop, and GC is allowed.
2500 //
2501 // The semantics of the InitializeNode include an implicit zeroing of
2502 // the new object from object header to the end of the object.
2503 // (The object header and end are determined by the AllocateNode.)
2504 //
2505 // Certain stores may be added as direct inputs to the InitializeNode.
2506 // These stores must update raw memory, and they must be to addresses
2507 // derived from the raw address produced by AllocateNode, and with
2508 // a constant offset. They must be ordered by increasing offset.
2509 // The first one is at in(RawStores), the last at in(req()-1).
2510 // Unlike most memory operations, they are not linked in a chain,
2511 // but are displayed in parallel as users of the rawmem output of
2512 // the allocation.
2513 //
2514 // (See comments in InitializeNode::capture_store, which continue
2515 // the example given above.)
2516 //
2517 // When the associated Allocate is macro-expanded, the InitializeNode
2518 // may be rewritten to optimize collected stores. A ClearArrayNode
2519 // may also be created at that point to represent any required zeroing.
2520 // The InitializeNode is then marked 'complete', prohibiting further
2521 // capturing of nearby memory operations.
2522 //
2523 // During macro-expansion, all captured initializations which store
2524 // constant values of 32 bits or smaller are coalesced (if advantagous)
2525 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2526 // initialized in fewer memory operations. Memory words which are
2527 // covered by neither tiles nor non-constant stores are pre-zeroed
2528 // by explicit stores of zero. (The code shape happens to do all
2529 // zeroing first, then all other stores, with both sequences occurring
2530 // in order of ascending offsets.)
2531 //
2532 // Alternatively, code may be inserted between an AllocateNode and its
2533 // InitializeNode, to perform arbitrary initialization of the new object.
2534 // E.g., the object copying intrinsics insert complex data transfers here.
2535 // The initialization must then be marked as 'complete' disable the
2536 // built-in zeroing semantics and the collection of initializing stores.
2537 //
2538 // While an InitializeNode is incomplete, reads from the memory state
2539 // produced by it are optimizable if they match the control edge and
2540 // new oop address associated with the allocation/initialization.
2541 // They return a stored value (if the offset matches) or else zero.
2542 // A write to the memory state, if it matches control and address,
2543 // and if it is to a constant offset, may be 'captured' by the
2544 // InitializeNode. It is cloned as a raw memory operation and rewired
2545 // inside the initialization, to the raw oop produced by the allocation.
2546 // Operations on addresses which are provably distinct (e.g., to
2547 // other AllocateNodes) are allowed to bypass the initialization.
2548 //
2549 // The effect of all this is to consolidate object initialization
2550 // (both arrays and non-arrays, both piecewise and bulk) into a
2551 // single location, where it can be optimized as a unit.
2552 //
2553 // Only stores with an offset less than TrackedInitializationLimit words
2554 // will be considered for capture by an InitializeNode. This puts a
2555 // reasonable limit on the complexity of optimized initializations.
2556
2557 //---------------------------InitializeNode------------------------------------
2558 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2559 : _is_complete(false),
2560 MemBarNode(C, adr_type, rawoop)
2561 {
2562 init_class_id(Class_Initialize);
2563
2564 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2565 assert(in(RawAddress) == rawoop, "proper init");
2566 // Note: allocation() can be NULL, for secondary initialization barriers
2567 }
2568
2569 // Since this node is not matched, it will be processed by the
2570 // register allocator. Declare that there are no constraints
2571 // on the allocation of the RawAddress edge.
2572 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2573 // This edge should be set to top, by the set_complete. But be conservative.
2574 if (idx == InitializeNode::RawAddress)
2575 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2576 return RegMask::Empty;
2577 }
2578
2579 Node* InitializeNode::memory(uint alias_idx) {
2580 Node* mem = in(Memory);
2581 if (mem->is_MergeMem()) {
2582 return mem->as_MergeMem()->memory_at(alias_idx);
2583 } else {
2584 // incoming raw memory is not split
2585 return mem;
2586 }
2587 }
2588
2589 bool InitializeNode::is_non_zero() {
2590 if (is_complete()) return false;
2591 remove_extra_zeroes();
2592 return (req() > RawStores);
2593 }
2594
2595 void InitializeNode::set_complete(PhaseGVN* phase) {
2596 assert(!is_complete(), "caller responsibility");
2597 _is_complete = true;
2598
2599 // After this node is complete, it contains a bunch of
2600 // raw-memory initializations. There is no need for
2601 // it to have anything to do with non-raw memory effects.
2602 // Therefore, tell all non-raw users to re-optimize themselves,
2603 // after skipping the memory effects of this initialization.
2604 PhaseIterGVN* igvn = phase->is_IterGVN();
2605 if (igvn) igvn->add_users_to_worklist(this);
2606 }
2607
2608 // convenience function
2609 // return false if the init contains any stores already
2610 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2611 InitializeNode* init = initialization();
2612 if (init == NULL || init->is_complete()) return false;
2613 init->remove_extra_zeroes();
2614 // for now, if this allocation has already collected any inits, bail:
2615 if (init->is_non_zero()) return false;
2616 init->set_complete(phase);
2617 return true;
2618 }
2619
2620 void InitializeNode::remove_extra_zeroes() {
2621 if (req() == RawStores) return;
2622 Node* zmem = zero_memory();
2623 uint fill = RawStores;
2624 for (uint i = fill; i < req(); i++) {
2625 Node* n = in(i);
2626 if (n->is_top() || n == zmem) continue; // skip
2627 if (fill < i) set_req(fill, n); // compact
2628 ++fill;
2629 }
2630 // delete any empty spaces created:
2631 while (fill < req()) {
2632 del_req(fill);
2633 }
2634 }
2635
2636 // Helper for remembering which stores go with which offsets.
2637 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2638 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2639 intptr_t offset = -1;
2640 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2641 phase, offset);
2642 if (base == NULL) return -1; // something is dead,
2643 if (offset < 0) return -1; // dead, dead
2644 return offset;
2645 }
2646
2647 // Helper for proving that an initialization expression is
2648 // "simple enough" to be folded into an object initialization.
2649 // Attempts to prove that a store's initial value 'n' can be captured
2650 // within the initialization without creating a vicious cycle, such as:
2651 // { Foo p = new Foo(); p.next = p; }
2652 // True for constants and parameters and small combinations thereof.
2653 bool InitializeNode::detect_init_independence(Node* n,
2654 bool st_is_pinned,
2655 int& count) {
2656 if (n == NULL) return true; // (can this really happen?)
2657 if (n->is_Proj()) n = n->in(0);
2658 if (n == this) return false; // found a cycle
2659 if (n->is_Con()) return true;
2660 if (n->is_Start()) return true; // params, etc., are OK
2661 if (n->is_Root()) return true; // even better
2662
2663 Node* ctl = n->in(0);
2664 if (ctl != NULL && !ctl->is_top()) {
2665 if (ctl->is_Proj()) ctl = ctl->in(0);
2666 if (ctl == this) return false;
2667
2668 // If we already know that the enclosing memory op is pinned right after
2669 // the init, then any control flow that the store has picked up
2670 // must have preceded the init, or else be equal to the init.
2671 // Even after loop optimizations (which might change control edges)
2672 // a store is never pinned *before* the availability of its inputs.
2673 if (!MemNode::all_controls_dominate(n, this))
2674 return false; // failed to prove a good control
2675
2676 }
2677
2678 // Check data edges for possible dependencies on 'this'.
2679 if ((count += 1) > 20) return false; // complexity limit
2680 for (uint i = 1; i < n->req(); i++) {
2681 Node* m = n->in(i);
2682 if (m == NULL || m == n || m->is_top()) continue;
2683 uint first_i = n->find_edge(m);
2684 if (i != first_i) continue; // process duplicate edge just once
2685 if (!detect_init_independence(m, st_is_pinned, count)) {
2686 return false;
2687 }
2688 }
2689
2690 return true;
2691 }
2692
2693 // Here are all the checks a Store must pass before it can be moved into
2694 // an initialization. Returns zero if a check fails.
2695 // On success, returns the (constant) offset to which the store applies,
2696 // within the initialized memory.
2697 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
2698 const int FAIL = 0;
2699 if (st->req() != MemNode::ValueIn + 1)
2700 return FAIL; // an inscrutable StoreNode (card mark?)
2701 Node* ctl = st->in(MemNode::Control);
2702 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
2703 return FAIL; // must be unconditional after the initialization
2704 Node* mem = st->in(MemNode::Memory);
2705 if (!(mem->is_Proj() && mem->in(0) == this))
2706 return FAIL; // must not be preceded by other stores
2707 Node* adr = st->in(MemNode::Address);
2708 intptr_t offset;
2709 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
2710 if (alloc == NULL)
2711 return FAIL; // inscrutable address
2712 if (alloc != allocation())
2713 return FAIL; // wrong allocation! (store needs to float up)
2714 Node* val = st->in(MemNode::ValueIn);
2715 int complexity_count = 0;
2716 if (!detect_init_independence(val, true, complexity_count))
2717 return FAIL; // stored value must be 'simple enough'
2718
2719 return offset; // success
2720 }
2721
2722 // Find the captured store in(i) which corresponds to the range
2723 // [start..start+size) in the initialized object.
2724 // If there is one, return its index i. If there isn't, return the
2725 // negative of the index where it should be inserted.
2726 // Return 0 if the queried range overlaps an initialization boundary
2727 // or if dead code is encountered.
2728 // If size_in_bytes is zero, do not bother with overlap checks.
2729 int InitializeNode::captured_store_insertion_point(intptr_t start,
2730 int size_in_bytes,
2731 PhaseTransform* phase) {
2732 const int FAIL = 0, MAX_STORE = BytesPerLong;
2733
2734 if (is_complete())
2735 return FAIL; // arraycopy got here first; punt
2736
2737 assert(allocation() != NULL, "must be present");
2738
2739 // no negatives, no header fields:
2740 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
2741
2742 // after a certain size, we bail out on tracking all the stores:
2743 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2744 if (start >= ti_limit) return FAIL;
2745
2746 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
2747 if (i >= limit) return -(int)i; // not found; here is where to put it
2748
2749 Node* st = in(i);
2750 intptr_t st_off = get_store_offset(st, phase);
2751 if (st_off < 0) {
2752 if (st != zero_memory()) {
2753 return FAIL; // bail out if there is dead garbage
2754 }
2755 } else if (st_off > start) {
2756 // ...we are done, since stores are ordered
2757 if (st_off < start + size_in_bytes) {
2758 return FAIL; // the next store overlaps
2759 }
2760 return -(int)i; // not found; here is where to put it
2761 } else if (st_off < start) {
2762 if (size_in_bytes != 0 &&
2763 start < st_off + MAX_STORE &&
2764 start < st_off + st->as_Store()->memory_size()) {
2765 return FAIL; // the previous store overlaps
2766 }
2767 } else {
2768 if (size_in_bytes != 0 &&
2769 st->as_Store()->memory_size() != size_in_bytes) {
2770 return FAIL; // mismatched store size
2771 }
2772 return i;
2773 }
2774
2775 ++i;
2776 }
2777 }
2778
2779 // Look for a captured store which initializes at the offset 'start'
2780 // with the given size. If there is no such store, and no other
2781 // initialization interferes, then return zero_memory (the memory
2782 // projection of the AllocateNode).
2783 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
2784 PhaseTransform* phase) {
2785 assert(stores_are_sane(phase), "");
2786 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2787 if (i == 0) {
2788 return NULL; // something is dead
2789 } else if (i < 0) {
2790 return zero_memory(); // just primordial zero bits here
2791 } else {
2792 Node* st = in(i); // here is the store at this position
2793 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
2794 return st;
2795 }
2796 }
2797
2798 // Create, as a raw pointer, an address within my new object at 'offset'.
2799 Node* InitializeNode::make_raw_address(intptr_t offset,
2800 PhaseTransform* phase) {
2801 Node* addr = in(RawAddress);
2802 if (offset != 0) {
2803 Compile* C = phase->C;
2804 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
2805 phase->MakeConX(offset)) );
2806 }
2807 return addr;
2808 }
2809
2810 // Clone the given store, converting it into a raw store
2811 // initializing a field or element of my new object.
2812 // Caller is responsible for retiring the original store,
2813 // with subsume_node or the like.
2814 //
2815 // From the example above InitializeNode::InitializeNode,
2816 // here are the old stores to be captured:
2817 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2818 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2819 //
2820 // Here is the changed code; note the extra edges on init:
2821 // alloc = (Allocate ...)
2822 // rawoop = alloc.RawAddress
2823 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
2824 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
2825 // init = (Initialize alloc.Control alloc.Memory rawoop
2826 // rawstore1 rawstore2)
2827 //
2828 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
2829 PhaseTransform* phase) {
2830 assert(stores_are_sane(phase), "");
2831
2832 if (start < 0) return NULL;
2833 assert(can_capture_store(st, phase) == start, "sanity");
2834
2835 Compile* C = phase->C;
2836 int size_in_bytes = st->memory_size();
2837 int i = captured_store_insertion_point(start, size_in_bytes, phase);
2838 if (i == 0) return NULL; // bail out
2839 Node* prev_mem = NULL; // raw memory for the captured store
2840 if (i > 0) {
2841 prev_mem = in(i); // there is a pre-existing store under this one
2842 set_req(i, C->top()); // temporarily disconnect it
2843 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
2844 } else {
2845 i = -i; // no pre-existing store
2846 prev_mem = zero_memory(); // a slice of the newly allocated object
2847 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
2848 set_req(--i, C->top()); // reuse this edge; it has been folded away
2849 else
2850 ins_req(i, C->top()); // build a new edge
2851 }
2852 Node* new_st = st->clone();
2853 new_st->set_req(MemNode::Control, in(Control));
2854 new_st->set_req(MemNode::Memory, prev_mem);
2855 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
2856 new_st = phase->transform(new_st);
2857
2858 // At this point, new_st might have swallowed a pre-existing store
2859 // at the same offset, or perhaps new_st might have disappeared,
2860 // if it redundantly stored the same value (or zero to fresh memory).
2861
2862 // In any case, wire it in:
2863 set_req(i, new_st);
2864
2865 // The caller may now kill the old guy.
2866 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
2867 assert(check_st == new_st || check_st == NULL, "must be findable");
2868 assert(!is_complete(), "");
2869 return new_st;
2870 }
2871
2872 static bool store_constant(jlong* tiles, int num_tiles,
2873 intptr_t st_off, int st_size,
2874 jlong con) {
2875 if ((st_off & (st_size-1)) != 0)
2876 return false; // strange store offset (assume size==2**N)
2877 address addr = (address)tiles + st_off;
2878 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
2879 switch (st_size) {
2880 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
2881 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
2882 case sizeof(jint): *(jint*) addr = (jint) con; break;
2883 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
2884 default: return false; // strange store size (detect size!=2**N here)
2885 }
2886 return true; // return success to caller
2887 }
2888
2889 // Coalesce subword constants into int constants and possibly
2890 // into long constants. The goal, if the CPU permits,
2891 // is to initialize the object with a small number of 64-bit tiles.
2892 // Also, convert floating-point constants to bit patterns.
2893 // Non-constants are not relevant to this pass.
2894 //
2895 // In terms of the running example on InitializeNode::InitializeNode
2896 // and InitializeNode::capture_store, here is the transformation
2897 // of rawstore1 and rawstore2 into rawstore12:
2898 // alloc = (Allocate ...)
2899 // rawoop = alloc.RawAddress
2900 // tile12 = 0x00010002
2901 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
2902 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
2903 //
2904 void
2905 InitializeNode::coalesce_subword_stores(intptr_t header_size,
2906 Node* size_in_bytes,
2907 PhaseGVN* phase) {
2908 Compile* C = phase->C;
2909
2910 assert(stores_are_sane(phase), "");
2911 // Note: After this pass, they are not completely sane,
2912 // since there may be some overlaps.
2913
2914 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
2915
2916 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
2917 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
2918 size_limit = MIN2(size_limit, ti_limit);
2919 size_limit = align_size_up(size_limit, BytesPerLong);
2920 int num_tiles = size_limit / BytesPerLong;
2921
2922 // allocate space for the tile map:
2923 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
2924 jlong tiles_buf[small_len];
2925 Node* nodes_buf[small_len];
2926 jlong inits_buf[small_len];
2927 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
2928 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2929 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
2930 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
2931 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
2932 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
2933 // tiles: exact bitwise model of all primitive constants
2934 // nodes: last constant-storing node subsumed into the tiles model
2935 // inits: which bytes (in each tile) are touched by any initializations
2936
2937 //// Pass A: Fill in the tile model with any relevant stores.
2938
2939 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
2940 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
2941 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
2942 Node* zmem = zero_memory(); // initially zero memory state
2943 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
2944 Node* st = in(i);
2945 intptr_t st_off = get_store_offset(st, phase);
2946
2947 // Figure out the store's offset and constant value:
2948 if (st_off < header_size) continue; //skip (ignore header)
2949 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
2950 int st_size = st->as_Store()->memory_size();
2951 if (st_off + st_size > size_limit) break;
2952
2953 // Record which bytes are touched, whether by constant or not.
2954 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
2955 continue; // skip (strange store size)
2956
2957 const Type* val = phase->type(st->in(MemNode::ValueIn));
2958 if (!val->singleton()) continue; //skip (non-con store)
2959 BasicType type = val->basic_type();
2960
2961 jlong con = 0;
2962 switch (type) {
2963 case T_INT: con = val->is_int()->get_con(); break;
2964 case T_LONG: con = val->is_long()->get_con(); break;
2965 case T_FLOAT: con = jint_cast(val->getf()); break;
2966 case T_DOUBLE: con = jlong_cast(val->getd()); break;
2967 default: continue; //skip (odd store type)
2968 }
2969
2970 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
2971 st->Opcode() == Op_StoreL) {
2972 continue; // This StoreL is already optimal.
2973 }
2974
2975 // Store down the constant.
2976 store_constant(tiles, num_tiles, st_off, st_size, con);
2977
2978 intptr_t j = st_off >> LogBytesPerLong;
2979
2980 if (type == T_INT && st_size == BytesPerInt
2981 && (st_off & BytesPerInt) == BytesPerInt) {
2982 jlong lcon = tiles[j];
2983 if (!Matcher::isSimpleConstant64(lcon) &&
2984 st->Opcode() == Op_StoreI) {
2985 // This StoreI is already optimal by itself.
2986 jint* intcon = (jint*) &tiles[j];
2987 intcon[1] = 0; // undo the store_constant()
2988
2989 // If the previous store is also optimal by itself, back up and
2990 // undo the action of the previous loop iteration... if we can.
2991 // But if we can't, just let the previous half take care of itself.
2992 st = nodes[j];
2993 st_off -= BytesPerInt;
2994 con = intcon[0];
2995 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
2996 assert(st_off >= header_size, "still ignoring header");
2997 assert(get_store_offset(st, phase) == st_off, "must be");
2998 assert(in(i-1) == zmem, "must be");
2999 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3000 assert(con == tcon->is_int()->get_con(), "must be");
3001 // Undo the effects of the previous loop trip, which swallowed st:
3002 intcon[0] = 0; // undo store_constant()
3003 set_req(i-1, st); // undo set_req(i, zmem)
3004 nodes[j] = NULL; // undo nodes[j] = st
3005 --old_subword; // undo ++old_subword
3006 }
3007 continue; // This StoreI is already optimal.
3008 }
3009 }
3010
3011 // This store is not needed.
3012 set_req(i, zmem);
3013 nodes[j] = st; // record for the moment
3014 if (st_size < BytesPerLong) // something has changed
3015 ++old_subword; // includes int/float, but who's counting...
3016 else ++old_long;
3017 }
3018
3019 if ((old_subword + old_long) == 0)
3020 return; // nothing more to do
3021
3022 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3023 // Be sure to insert them before overlapping non-constant stores.
3024 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3025 for (int j = 0; j < num_tiles; j++) {
3026 jlong con = tiles[j];
3027 jlong init = inits[j];
3028 if (con == 0) continue;
3029 jint con0, con1; // split the constant, address-wise
3030 jint init0, init1; // split the init map, address-wise
3031 { union { jlong con; jint intcon[2]; } u;
3032 u.con = con;
3033 con0 = u.intcon[0];
3034 con1 = u.intcon[1];
3035 u.con = init;
3036 init0 = u.intcon[0];
3037 init1 = u.intcon[1];
3038 }
3039
3040 Node* old = nodes[j];
3041 assert(old != NULL, "need the prior store");
3042 intptr_t offset = (j * BytesPerLong);
3043
3044 bool split = !Matcher::isSimpleConstant64(con);
3045
3046 if (offset < header_size) {
3047 assert(offset + BytesPerInt >= header_size, "second int counts");
3048 assert(*(jint*)&tiles[j] == 0, "junk in header");
3049 split = true; // only the second word counts
3050 // Example: int a[] = { 42 ... }
3051 } else if (con0 == 0 && init0 == -1) {
3052 split = true; // first word is covered by full inits
3053 // Example: int a[] = { ... foo(), 42 ... }
3054 } else if (con1 == 0 && init1 == -1) {
3055 split = true; // second word is covered by full inits
3056 // Example: int a[] = { ... 42, foo() ... }
3057 }
3058
3059 // Here's a case where init0 is neither 0 nor -1:
3060 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3061 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3062 // In this case the tile is not split; it is (jlong)42.
3063 // The big tile is stored down, and then the foo() value is inserted.
3064 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3065
3066 Node* ctl = old->in(MemNode::Control);
3067 Node* adr = make_raw_address(offset, phase);
3068 const TypePtr* atp = TypeRawPtr::BOTTOM;
3069
3070 // One or two coalesced stores to plop down.
3071 Node* st[2];
3072 intptr_t off[2];
3073 int nst = 0;
3074 if (!split) {
3075 ++new_long;
3076 off[nst] = offset;
3077 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3078 phase->longcon(con), T_LONG);
3079 } else {
3080 // Omit either if it is a zero.
3081 if (con0 != 0) {
3082 ++new_int;
3083 off[nst] = offset;
3084 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3085 phase->intcon(con0), T_INT);
3086 }
3087 if (con1 != 0) {
3088 ++new_int;
3089 offset += BytesPerInt;
3090 adr = make_raw_address(offset, phase);
3091 off[nst] = offset;
3092 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3093 phase->intcon(con1), T_INT);
3094 }
3095 }
3096
3097 // Insert second store first, then the first before the second.
3098 // Insert each one just before any overlapping non-constant stores.
3099 while (nst > 0) {
3100 Node* st1 = st[--nst];
3101 C->copy_node_notes_to(st1, old);
3102 st1 = phase->transform(st1);
3103 offset = off[nst];
3104 assert(offset >= header_size, "do not smash header");
3105 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3106 guarantee(ins_idx != 0, "must re-insert constant store");
3107 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3108 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3109 set_req(--ins_idx, st1);
3110 else
3111 ins_req(ins_idx, st1);
3112 }
3113 }
3114
3115 if (PrintCompilation && WizardMode)
3116 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3117 old_subword, old_long, new_int, new_long);
3118 if (C->log() != NULL)
3119 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3120 old_subword, old_long, new_int, new_long);
3121
3122 // Clean up any remaining occurrences of zmem:
3123 remove_extra_zeroes();
3124 }
3125
3126 // Explore forward from in(start) to find the first fully initialized
3127 // word, and return its offset. Skip groups of subword stores which
3128 // together initialize full words. If in(start) is itself part of a
3129 // fully initialized word, return the offset of in(start). If there
3130 // are no following full-word stores, or if something is fishy, return
3131 // a negative value.
3132 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3133 int int_map = 0;
3134 intptr_t int_map_off = 0;
3135 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3136
3137 for (uint i = start, limit = req(); i < limit; i++) {
3138 Node* st = in(i);
3139
3140 intptr_t st_off = get_store_offset(st, phase);
3141 if (st_off < 0) break; // return conservative answer
3142
3143 int st_size = st->as_Store()->memory_size();
3144 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3145 return st_off; // we found a complete word init
3146 }
3147
3148 // update the map:
3149
3150 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3151 if (this_int_off != int_map_off) {
3152 // reset the map:
3153 int_map = 0;
3154 int_map_off = this_int_off;
3155 }
3156
3157 int subword_off = st_off - this_int_off;
3158 int_map |= right_n_bits(st_size) << subword_off;
3159 if ((int_map & FULL_MAP) == FULL_MAP) {
3160 return this_int_off; // we found a complete word init
3161 }
3162
3163 // Did this store hit or cross the word boundary?
3164 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3165 if (next_int_off == this_int_off + BytesPerInt) {
3166 // We passed the current int, without fully initializing it.
3167 int_map_off = next_int_off;
3168 int_map >>= BytesPerInt;
3169 } else if (next_int_off > this_int_off + BytesPerInt) {
3170 // We passed the current and next int.
3171 return this_int_off + BytesPerInt;
3172 }
3173 }
3174
3175 return -1;
3176 }
3177
3178
3179 // Called when the associated AllocateNode is expanded into CFG.
3180 // At this point, we may perform additional optimizations.
3181 // Linearize the stores by ascending offset, to make memory
3182 // activity as coherent as possible.
3183 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3184 intptr_t header_size,
3185 Node* size_in_bytes,
3186 PhaseGVN* phase) {
3187 assert(!is_complete(), "not already complete");
3188 assert(stores_are_sane(phase), "");
3189 assert(allocation() != NULL, "must be present");
3190
3191 remove_extra_zeroes();
3192
3193 if (ReduceFieldZeroing || ReduceBulkZeroing)
3194 // reduce instruction count for common initialization patterns
3195 coalesce_subword_stores(header_size, size_in_bytes, phase);
3196
3197 Node* zmem = zero_memory(); // initially zero memory state
3198 Node* inits = zmem; // accumulating a linearized chain of inits
3199 #ifdef ASSERT
3200 intptr_t first_offset = allocation()->minimum_header_size();
3201 intptr_t last_init_off = first_offset; // previous init offset
3202 intptr_t last_init_end = first_offset; // previous init offset+size
3203 intptr_t last_tile_end = first_offset; // previous tile offset+size
3204 #endif
3205 intptr_t zeroes_done = header_size;
3206
3207 bool do_zeroing = true; // we might give up if inits are very sparse
3208 int big_init_gaps = 0; // how many large gaps have we seen?
3209
3210 if (ZeroTLAB) do_zeroing = false;
3211 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3212
3213 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3214 Node* st = in(i);
3215 intptr_t st_off = get_store_offset(st, phase);
3216 if (st_off < 0)
3217 break; // unknown junk in the inits
3218 if (st->in(MemNode::Memory) != zmem)
3219 break; // complicated store chains somehow in list
3220
3221 int st_size = st->as_Store()->memory_size();
3222 intptr_t next_init_off = st_off + st_size;
3223
3224 if (do_zeroing && zeroes_done < next_init_off) {
3225 // See if this store needs a zero before it or under it.
3226 intptr_t zeroes_needed = st_off;
3227
3228 if (st_size < BytesPerInt) {
3229 // Look for subword stores which only partially initialize words.
3230 // If we find some, we must lay down some word-level zeroes first,
3231 // underneath the subword stores.
3232 //
3233 // Examples:
3234 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3235 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3236 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3237 //
3238 // Note: coalesce_subword_stores may have already done this,
3239 // if it was prompted by constant non-zero subword initializers.
3240 // But this case can still arise with non-constant stores.
3241
3242 intptr_t next_full_store = find_next_fullword_store(i, phase);
3243
3244 // In the examples above:
3245 // in(i) p q r s x y z
3246 // st_off 12 13 14 15 12 13 14
3247 // st_size 1 1 1 1 1 1 1
3248 // next_full_s. 12 16 16 16 16 16 16
3249 // z's_done 12 16 16 16 12 16 12
3250 // z's_needed 12 16 16 16 16 16 16
3251 // zsize 0 0 0 0 4 0 4
3252 if (next_full_store < 0) {
3253 // Conservative tack: Zero to end of current word.
3254 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3255 } else {
3256 // Zero to beginning of next fully initialized word.
3257 // Or, don't zero at all, if we are already in that word.
3258 assert(next_full_store >= zeroes_needed, "must go forward");
3259 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3260 zeroes_needed = next_full_store;
3261 }
3262 }
3263
3264 if (zeroes_needed > zeroes_done) {
3265 intptr_t zsize = zeroes_needed - zeroes_done;
3266 // Do some incremental zeroing on rawmem, in parallel with inits.
3267 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3268 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3269 zeroes_done, zeroes_needed,
3270 phase);
3271 zeroes_done = zeroes_needed;
3272 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3273 do_zeroing = false; // leave the hole, next time
3274 }
3275 }
3276
3277 // Collect the store and move on:
3278 st->set_req(MemNode::Memory, inits);
3279 inits = st; // put it on the linearized chain
3280 set_req(i, zmem); // unhook from previous position
3281
3282 if (zeroes_done == st_off)
3283 zeroes_done = next_init_off;
3284
3285 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3286
3287 #ifdef ASSERT
3288 // Various order invariants. Weaker than stores_are_sane because
3289 // a large constant tile can be filled in by smaller non-constant stores.
3290 assert(st_off >= last_init_off, "inits do not reverse");
3291 last_init_off = st_off;
3292 const Type* val = NULL;
3293 if (st_size >= BytesPerInt &&
3294 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3295 (int)val->basic_type() < (int)T_OBJECT) {
3296 assert(st_off >= last_tile_end, "tiles do not overlap");
3297 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3298 last_tile_end = MAX2(last_tile_end, next_init_off);
3299 } else {
3300 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3301 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3302 assert(st_off >= last_init_end, "inits do not overlap");
3303 last_init_end = next_init_off; // it's a non-tile
3304 }
3305 #endif //ASSERT
3306 }
3307
3308 remove_extra_zeroes(); // clear out all the zmems left over
3309 add_req(inits);
3310
3311 if (!ZeroTLAB) {
3312 // If anything remains to be zeroed, zero it all now.
3313 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3314 // if it is the last unused 4 bytes of an instance, forget about it
3315 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3316 if (zeroes_done + BytesPerLong >= size_limit) {
3317 assert(allocation() != NULL, "");
3318 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3319 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3320 if (zeroes_done == k->layout_helper())
3321 zeroes_done = size_limit;
3322 }
3323 if (zeroes_done < size_limit) {
3324 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3325 zeroes_done, size_in_bytes, phase);
3326 }
3327 }
3328
3329 set_complete(phase);
3330 return rawmem;
3331 }
3332
3333
3334 #ifdef ASSERT
3335 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3336 if (is_complete())
3337 return true; // stores could be anything at this point
3338 assert(allocation() != NULL, "must be present");
3339 intptr_t last_off = allocation()->minimum_header_size();
3340 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3341 Node* st = in(i);
3342 intptr_t st_off = get_store_offset(st, phase);
3343 if (st_off < 0) continue; // ignore dead garbage
3344 if (last_off > st_off) {
3345 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3346 this->dump(2);
3347 assert(false, "ascending store offsets");
3348 return false;
3349 }
3350 last_off = st_off + st->as_Store()->memory_size();
3351 }
3352 return true;
3353 }
3354 #endif //ASSERT
3355
3356
3357
3358
3359 //============================MergeMemNode=====================================
3360 //
3361 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3362 // contributing store or call operations. Each contributor provides the memory
3363 // state for a particular "alias type" (see Compile::alias_type). For example,
3364 // if a MergeMem has an input X for alias category #6, then any memory reference
3365 // to alias category #6 may use X as its memory state input, as an exact equivalent
3366 // to using the MergeMem as a whole.
3367 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3368 //
3369 // (Here, the <N> notation gives the index of the relevant adr_type.)
3370 //
3371 // In one special case (and more cases in the future), alias categories overlap.
3372 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3373 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3374 // it is exactly equivalent to that state W:
3375 // MergeMem(<Bot>: W) <==> W
3376 //
3377 // Usually, the merge has more than one input. In that case, where inputs
3378 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3379 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3380 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3381 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3382 //
3383 // A merge can take a "wide" memory state as one of its narrow inputs.
3384 // This simply means that the merge observes out only the relevant parts of
3385 // the wide input. That is, wide memory states arriving at narrow merge inputs
3386 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3387 //
3388 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3389 // and that memory slices "leak through":
3390 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3391 //
3392 // But, in such a cascade, repeated memory slices can "block the leak":
3393 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3394 //
3395 // In the last example, Y is not part of the combined memory state of the
3396 // outermost MergeMem. The system must, of course, prevent unschedulable
3397 // memory states from arising, so you can be sure that the state Y is somehow
3398 // a precursor to state Y'.
3399 //
3400 //
3401 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3402 // of each MergeMemNode array are exactly the numerical alias indexes, including
3403 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3404 // Compile::alias_type (and kin) produce and manage these indexes.
3405 //
3406 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3407 // (Note that this provides quick access to the top node inside MergeMem methods,
3408 // without the need to reach out via TLS to Compile::current.)
3409 //
3410 // As a consequence of what was just described, a MergeMem that represents a full
3411 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3412 // containing all alias categories.
3413 //
3414 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3415 //
3416 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3417 // a memory state for the alias type <N>, or else the top node, meaning that
3418 // there is no particular input for that alias type. Note that the length of
3419 // a MergeMem is variable, and may be extended at any time to accommodate new
3420 // memory states at larger alias indexes. When merges grow, they are of course
3421 // filled with "top" in the unused in() positions.
3422 //
3423 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3424 // (Top was chosen because it works smoothly with passes like GCM.)
3425 //
3426 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3427 // the type of random VM bits like TLS references.) Since it is always the
3428 // first non-Bot memory slice, some low-level loops use it to initialize an
3429 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3430 //
3431 //
3432 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3433 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3434 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3435 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3436 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3437 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3438 //
3439 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3440 // really that different from the other memory inputs. An abbreviation called
3441 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3442 //
3443 //
3444 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3445 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3446 // that "emerges though" the base memory will be marked as excluding the alias types
3447 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3448 //
3449 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3450 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3451 //
3452 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3453 // (It is currently unimplemented.) As you can see, the resulting merge is
3454 // actually a disjoint union of memory states, rather than an overlay.
3455 //
3456
3457 //------------------------------MergeMemNode-----------------------------------
3458 Node* MergeMemNode::make_empty_memory() {
3459 Node* empty_memory = (Node*) Compile::current()->top();
3460 assert(empty_memory->is_top(), "correct sentinel identity");
3461 return empty_memory;
3462 }
3463
3464 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3465 init_class_id(Class_MergeMem);
3466 // all inputs are nullified in Node::Node(int)
3467 // set_input(0, NULL); // no control input
3468
3469 // Initialize the edges uniformly to top, for starters.
3470 Node* empty_mem = make_empty_memory();
3471 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3472 init_req(i,empty_mem);
3473 }
3474 assert(empty_memory() == empty_mem, "");
3475
3476 if( new_base != NULL && new_base->is_MergeMem() ) {
3477 MergeMemNode* mdef = new_base->as_MergeMem();
3478 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3479 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3480 mms.set_memory(mms.memory2());
3481 }
3482 assert(base_memory() == mdef->base_memory(), "");
3483 } else {
3484 set_base_memory(new_base);
3485 }
3486 }
3487
3488 // Make a new, untransformed MergeMem with the same base as 'mem'.
3489 // If mem is itself a MergeMem, populate the result with the same edges.
3490 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3491 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3492 }
3493
3494 //------------------------------cmp--------------------------------------------
3495 uint MergeMemNode::hash() const { return NO_HASH; }
3496 uint MergeMemNode::cmp( const Node &n ) const {
3497 return (&n == this); // Always fail except on self
3498 }
3499
3500 //------------------------------Identity---------------------------------------
3501 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3502 // Identity if this merge point does not record any interesting memory
3503 // disambiguations.
3504 Node* base_mem = base_memory();
3505 Node* empty_mem = empty_memory();
3506 if (base_mem != empty_mem) { // Memory path is not dead?
3507 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3508 Node* mem = in(i);
3509 if (mem != empty_mem && mem != base_mem) {
3510 return this; // Many memory splits; no change
3511 }
3512 }
3513 }
3514 return base_mem; // No memory splits; ID on the one true input
3515 }
3516
3517 //------------------------------Ideal------------------------------------------
3518 // This method is invoked recursively on chains of MergeMem nodes
3519 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3520 // Remove chain'd MergeMems
3521 //
3522 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3523 // relative to the "in(Bot)". Since we are patching both at the same time,
3524 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3525 // but rewrite each "in(i)" relative to the new "in(Bot)".
3526 Node *progress = NULL;
3527
3528
3529 Node* old_base = base_memory();
3530 Node* empty_mem = empty_memory();
3531 if (old_base == empty_mem)
3532 return NULL; // Dead memory path.
3533
3534 MergeMemNode* old_mbase;
3535 if (old_base != NULL && old_base->is_MergeMem())
3536 old_mbase = old_base->as_MergeMem();
3537 else
3538 old_mbase = NULL;
3539 Node* new_base = old_base;
3540
3541 // simplify stacked MergeMems in base memory
3542 if (old_mbase) new_base = old_mbase->base_memory();
3543
3544 // the base memory might contribute new slices beyond my req()
3545 if (old_mbase) grow_to_match(old_mbase);
3546
3547 // Look carefully at the base node if it is a phi.
3548 PhiNode* phi_base;
3549 if (new_base != NULL && new_base->is_Phi())
3550 phi_base = new_base->as_Phi();
3551 else
3552 phi_base = NULL;
3553
3554 Node* phi_reg = NULL;
3555 uint phi_len = (uint)-1;
3556 if (phi_base != NULL && !phi_base->is_copy()) {
3557 // do not examine phi if degraded to a copy
3558 phi_reg = phi_base->region();
3559 phi_len = phi_base->req();
3560 // see if the phi is unfinished
3561 for (uint i = 1; i < phi_len; i++) {
3562 if (phi_base->in(i) == NULL) {
3563 // incomplete phi; do not look at it yet!
3564 phi_reg = NULL;
3565 phi_len = (uint)-1;
3566 break;
3567 }
3568 }
3569 }
3570
3571 // Note: We do not call verify_sparse on entry, because inputs
3572 // can normalize to the base_memory via subsume_node or similar
3573 // mechanisms. This method repairs that damage.
3574
3575 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3576
3577 // Look at each slice.
3578 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3579 Node* old_in = in(i);
3580 // calculate the old memory value
3581 Node* old_mem = old_in;
3582 if (old_mem == empty_mem) old_mem = old_base;
3583 assert(old_mem == memory_at(i), "");
3584
3585 // maybe update (reslice) the old memory value
3586
3587 // simplify stacked MergeMems
3588 Node* new_mem = old_mem;
3589 MergeMemNode* old_mmem;
3590 if (old_mem != NULL && old_mem->is_MergeMem())
3591 old_mmem = old_mem->as_MergeMem();
3592 else
3593 old_mmem = NULL;
3594 if (old_mmem == this) {
3595 // This can happen if loops break up and safepoints disappear.
3596 // A merge of BotPtr (default) with a RawPtr memory derived from a
3597 // safepoint can be rewritten to a merge of the same BotPtr with
3598 // the BotPtr phi coming into the loop. If that phi disappears
3599 // also, we can end up with a self-loop of the mergemem.
3600 // In general, if loops degenerate and memory effects disappear,
3601 // a mergemem can be left looking at itself. This simply means
3602 // that the mergemem's default should be used, since there is
3603 // no longer any apparent effect on this slice.
3604 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3605 // from start. Update the input to TOP.
3606 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3607 }
3608 else if (old_mmem != NULL) {
3609 new_mem = old_mmem->memory_at(i);
3610 }
3611 // else preceeding memory was not a MergeMem
3612
3613 // replace equivalent phis (unfortunately, they do not GVN together)
3614 if (new_mem != NULL && new_mem != new_base &&
3615 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3616 if (new_mem->is_Phi()) {
3617 PhiNode* phi_mem = new_mem->as_Phi();
3618 for (uint i = 1; i < phi_len; i++) {
3619 if (phi_base->in(i) != phi_mem->in(i)) {
3620 phi_mem = NULL;
3621 break;
3622 }
3623 }
3624 if (phi_mem != NULL) {
3625 // equivalent phi nodes; revert to the def
3626 new_mem = new_base;
3627 }
3628 }
3629 }
3630
3631 // maybe store down a new value
3632 Node* new_in = new_mem;
3633 if (new_in == new_base) new_in = empty_mem;
3634
3635 if (new_in != old_in) {
3636 // Warning: Do not combine this "if" with the previous "if"
3637 // A memory slice might have be be rewritten even if it is semantically
3638 // unchanged, if the base_memory value has changed.
3639 set_req(i, new_in);
3640 progress = this; // Report progress
3641 }
3642 }
3643
3644 if (new_base != old_base) {
3645 set_req(Compile::AliasIdxBot, new_base);
3646 // Don't use set_base_memory(new_base), because we need to update du.
3647 assert(base_memory() == new_base, "");
3648 progress = this;
3649 }
3650
3651 if( base_memory() == this ) {
3652 // a self cycle indicates this memory path is dead
3653 set_req(Compile::AliasIdxBot, empty_mem);
3654 }
3655
3656 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3657 // Recursion must occur after the self cycle check above
3658 if( base_memory()->is_MergeMem() ) {
3659 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3660 Node *m = phase->transform(new_mbase); // Rollup any cycles
3661 if( m != NULL && (m->is_top() ||
3662 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3663 // propagate rollup of dead cycle to self
3664 set_req(Compile::AliasIdxBot, empty_mem);
3665 }
3666 }
3667
3668 if( base_memory() == empty_mem ) {
3669 progress = this;
3670 // Cut inputs during Parse phase only.
3671 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3672 if( !can_reshape ) {
3673 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3674 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3675 }
3676 }
3677 }
3678
3679 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3680 // Check if PhiNode::Ideal's "Split phis through memory merges"
3681 // transform should be attempted. Look for this->phi->this cycle.
3682 uint merge_width = req();
3683 if (merge_width > Compile::AliasIdxRaw) {
3684 PhiNode* phi = base_memory()->as_Phi();
3685 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3686 if (phi->in(i) == this) {
3687 phase->is_IterGVN()->_worklist.push(phi);
3688 break;
3689 }
3690 }
3691 }
3692 }
3693
3694 assert(progress || verify_sparse(), "please, no dups of base");
3695 return progress;
3696 }
3697
3698 //-------------------------set_base_memory-------------------------------------
3699 void MergeMemNode::set_base_memory(Node *new_base) {
3700 Node* empty_mem = empty_memory();
3701 set_req(Compile::AliasIdxBot, new_base);
3702 assert(memory_at(req()) == new_base, "must set default memory");
3703 // Clear out other occurrences of new_base:
3704 if (new_base != empty_mem) {
3705 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3706 if (in(i) == new_base) set_req(i, empty_mem);
3707 }
3708 }
3709 }
3710
3711 //------------------------------out_RegMask------------------------------------
3712 const RegMask &MergeMemNode::out_RegMask() const {
3713 return RegMask::Empty;
3714 }
3715
3716 //------------------------------dump_spec--------------------------------------
3717 #ifndef PRODUCT
3718 void MergeMemNode::dump_spec(outputStream *st) const {
3719 st->print(" {");
3720 Node* base_mem = base_memory();
3721 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
3722 Node* mem = memory_at(i);
3723 if (mem == base_mem) { st->print(" -"); continue; }
3724 st->print( " N%d:", mem->_idx );
3725 Compile::current()->get_adr_type(i)->dump_on(st);
3726 }
3727 st->print(" }");
3728 }
3729 #endif // !PRODUCT
3730
3731
3732 #ifdef ASSERT
3733 static bool might_be_same(Node* a, Node* b) {
3734 if (a == b) return true;
3735 if (!(a->is_Phi() || b->is_Phi())) return false;
3736 // phis shift around during optimization
3737 return true; // pretty stupid...
3738 }
3739
3740 // verify a narrow slice (either incoming or outgoing)
3741 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
3742 if (!VerifyAliases) return; // don't bother to verify unless requested
3743 if (is_error_reported()) return; // muzzle asserts when debugging an error
3744 if (Node::in_dump()) return; // muzzle asserts when printing
3745 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
3746 assert(n != NULL, "");
3747 // Elide intervening MergeMem's
3748 while (n->is_MergeMem()) {
3749 n = n->as_MergeMem()->memory_at(alias_idx);
3750 }
3751 Compile* C = Compile::current();
3752 const TypePtr* n_adr_type = n->adr_type();
3753 if (n == m->empty_memory()) {
3754 // Implicit copy of base_memory()
3755 } else if (n_adr_type != TypePtr::BOTTOM) {
3756 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
3757 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
3758 } else {
3759 // A few places like make_runtime_call "know" that VM calls are narrow,
3760 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
3761 bool expected_wide_mem = false;
3762 if (n == m->base_memory()) {
3763 expected_wide_mem = true;
3764 } else if (alias_idx == Compile::AliasIdxRaw ||
3765 n == m->memory_at(Compile::AliasIdxRaw)) {
3766 expected_wide_mem = true;
3767 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
3768 // memory can "leak through" calls on channels that
3769 // are write-once. Allow this also.
3770 expected_wide_mem = true;
3771 }
3772 assert(expected_wide_mem, "expected narrow slice replacement");
3773 }
3774 }
3775 #else // !ASSERT
3776 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
3777 #endif
3778
3779
3780 //-----------------------------memory_at---------------------------------------
3781 Node* MergeMemNode::memory_at(uint alias_idx) const {
3782 assert(alias_idx >= Compile::AliasIdxRaw ||
3783 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
3784 "must avoid base_memory and AliasIdxTop");
3785
3786 // Otherwise, it is a narrow slice.
3787 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
3788 Compile *C = Compile::current();
3789 if (is_empty_memory(n)) {
3790 // the array is sparse; empty slots are the "top" node
3791 n = base_memory();
3792 assert(Node::in_dump()
3793 || n == NULL || n->bottom_type() == Type::TOP
3794 || n->adr_type() == TypePtr::BOTTOM
3795 || n->adr_type() == TypeRawPtr::BOTTOM
3796 || Compile::current()->AliasLevel() == 0,
3797 "must be a wide memory");
3798 // AliasLevel == 0 if we are organizing the memory states manually.
3799 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
3800 } else {
3801 // make sure the stored slice is sane
3802 #ifdef ASSERT
3803 if (is_error_reported() || Node::in_dump()) {
3804 } else if (might_be_same(n, base_memory())) {
3805 // Give it a pass: It is a mostly harmless repetition of the base.
3806 // This can arise normally from node subsumption during optimization.
3807 } else {
3808 verify_memory_slice(this, alias_idx, n);
3809 }
3810 #endif
3811 }
3812 return n;
3813 }
3814
3815 //---------------------------set_memory_at-------------------------------------
3816 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
3817 verify_memory_slice(this, alias_idx, n);
3818 Node* empty_mem = empty_memory();
3819 if (n == base_memory()) n = empty_mem; // collapse default
3820 uint need_req = alias_idx+1;
3821 if (req() < need_req) {
3822 if (n == empty_mem) return; // already the default, so do not grow me
3823 // grow the sparse array
3824 do {
3825 add_req(empty_mem);
3826 } while (req() < need_req);
3827 }
3828 set_req( alias_idx, n );
3829 }
3830
3831
3832
3833 //--------------------------iteration_setup------------------------------------
3834 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
3835 if (other != NULL) {
3836 grow_to_match(other);
3837 // invariant: the finite support of mm2 is within mm->req()
3838 #ifdef ASSERT
3839 for (uint i = req(); i < other->req(); i++) {
3840 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
3841 }
3842 #endif
3843 }
3844 // Replace spurious copies of base_memory by top.
3845 Node* base_mem = base_memory();
3846 if (base_mem != NULL && !base_mem->is_top()) {
3847 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
3848 if (in(i) == base_mem)
3849 set_req(i, empty_memory());
3850 }
3851 }
3852 }
3853
3854 //---------------------------grow_to_match-------------------------------------
3855 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
3856 Node* empty_mem = empty_memory();
3857 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
3858 // look for the finite support of the other memory
3859 for (uint i = other->req(); --i >= req(); ) {
3860 if (other->in(i) != empty_mem) {
3861 uint new_len = i+1;
3862 while (req() < new_len) add_req(empty_mem);
3863 break;
3864 }
3865 }
3866 }
3867
3868 //---------------------------verify_sparse-------------------------------------
3869 #ifndef PRODUCT
3870 bool MergeMemNode::verify_sparse() const {
3871 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
3872 Node* base_mem = base_memory();
3873 // The following can happen in degenerate cases, since empty==top.
3874 if (is_empty_memory(base_mem)) return true;
3875 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3876 assert(in(i) != NULL, "sane slice");
3877 if (in(i) == base_mem) return false; // should have been the sentinel value!
3878 }
3879 return true;
3880 }
3881
3882 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
3883 Node* n;
3884 n = mm->in(idx);
3885 if (mem == n) return true; // might be empty_memory()
3886 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
3887 if (mem == n) return true;
3888 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
3889 if (mem == n) return true;
3890 if (n == NULL) break;
3891 }
3892 return false;
3893 }
3894 #endif // !PRODUCT