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