1 /*
2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/constnode.hpp"
34 #include "opto/convertnode.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/machnode.hpp"
37 #include "opto/matcher.hpp"
38 #include "opto/memnode.hpp"
39 #include "opto/mulnode.hpp"
40 #include "opto/narrownode.hpp"
41 #include "opto/phaseX.hpp"
42 #include "opto/regmask.hpp"
43
44 // Portions of code courtesy of Clifford Click
45
46 // Optimization - Graph Style
47
48 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
49
50 //=============================================================================
51 uint MemNode::size_of() const { return sizeof(*this); }
52
53 const TypePtr *MemNode::adr_type() const {
54 Node* adr = in(Address);
55 const TypePtr* cross_check = NULL;
56 DEBUG_ONLY(cross_check = _adr_type);
57 return calculate_adr_type(adr->bottom_type(), cross_check);
58 }
59
60 #ifndef PRODUCT
61 void MemNode::dump_spec(outputStream *st) const {
62 if (in(Address) == NULL) return; // node is dead
63 #ifndef ASSERT
64 // fake the missing field
65 const TypePtr* _adr_type = NULL;
66 if (in(Address) != NULL)
67 _adr_type = in(Address)->bottom_type()->isa_ptr();
68 #endif
69 dump_adr_type(this, _adr_type, st);
70
71 Compile* C = Compile::current();
72 if( C->alias_type(_adr_type)->is_volatile() )
73 st->print(" Volatile!");
74 }
75
76 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
77 st->print(" @");
78 if (adr_type == NULL) {
79 st->print("NULL");
80 } else {
81 adr_type->dump_on(st);
82 Compile* C = Compile::current();
83 Compile::AliasType* atp = NULL;
84 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
85 if (atp == NULL)
86 st->print(", idx=?\?;");
87 else if (atp->index() == Compile::AliasIdxBot)
88 st->print(", idx=Bot;");
89 else if (atp->index() == Compile::AliasIdxTop)
90 st->print(", idx=Top;");
91 else if (atp->index() == Compile::AliasIdxRaw)
92 st->print(", idx=Raw;");
93 else {
94 ciField* field = atp->field();
95 if (field) {
96 st->print(", name=");
97 field->print_name_on(st);
98 }
99 st->print(", idx=%d;", atp->index());
100 }
101 }
102 }
103
104 extern void print_alias_types();
105
106 #endif
107
108 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
109 assert((t_oop != NULL), "sanity");
110 bool is_instance = t_oop->is_known_instance_field();
111 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
112 (load != NULL) && load->is_Load() &&
113 (phase->is_IterGVN() != NULL);
114 if (!(is_instance || is_boxed_value_load))
115 return mchain; // don't try to optimize non-instance types
116 uint instance_id = t_oop->instance_id();
117 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
118 Node *prev = NULL;
119 Node *result = mchain;
120 while (prev != result) {
121 prev = result;
122 if (result == start_mem)
123 break; // hit one of our sentinels
124 // skip over a call which does not affect this memory slice
125 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
126 Node *proj_in = result->in(0);
127 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
128 break; // hit one of our sentinels
129 } else if (proj_in->is_Call()) {
130 CallNode *call = proj_in->as_Call();
131 if (!call->may_modify(t_oop, phase)) { // returns false for instances
132 result = call->in(TypeFunc::Memory);
133 }
134 } else if (proj_in->is_Initialize()) {
135 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
136 // Stop if this is the initialization for the object instance which
137 // which contains this memory slice, otherwise skip over it.
138 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
139 break;
140 }
141 if (is_instance) {
142 result = proj_in->in(TypeFunc::Memory);
143 } else if (is_boxed_value_load) {
144 Node* klass = alloc->in(AllocateNode::KlassNode);
145 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
146 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
147 result = proj_in->in(TypeFunc::Memory); // not related allocation
148 }
149 }
150 } else if (proj_in->is_MemBar()) {
151 result = proj_in->in(TypeFunc::Memory);
152 } else {
153 assert(false, "unexpected projection");
154 }
155 } else if (result->is_ClearArray()) {
156 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
157 // Can not bypass initialization of the instance
158 // we are looking for.
159 break;
160 }
161 // Otherwise skip it (the call updated 'result' value).
162 } else if (result->is_MergeMem()) {
163 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
164 }
165 }
166 return result;
167 }
168
169 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
170 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
171 if (t_oop == NULL)
172 return mchain; // don't try to optimize non-oop types
173 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
174 bool is_instance = t_oop->is_known_instance_field();
175 PhaseIterGVN *igvn = phase->is_IterGVN();
176 if (is_instance && igvn != NULL && result->is_Phi()) {
177 PhiNode *mphi = result->as_Phi();
178 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
179 const TypePtr *t = mphi->adr_type();
180 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
181 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
182 t->is_oopptr()->cast_to_exactness(true)
183 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
184 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
185 // clone the Phi with our address type
186 result = mphi->split_out_instance(t_adr, igvn);
187 } else {
188 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
189 }
190 }
191 return result;
192 }
193
194 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
195 uint alias_idx = phase->C->get_alias_index(tp);
196 Node *mem = mmem;
197 #ifdef ASSERT
198 {
199 // Check that current type is consistent with the alias index used during graph construction
200 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
201 bool consistent = adr_check == NULL || adr_check->empty() ||
202 phase->C->must_alias(adr_check, alias_idx );
203 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
204 if( !consistent && adr_check != NULL && !adr_check->empty() &&
205 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
206 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
207 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
208 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
209 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
210 // don't assert if it is dead code.
211 consistent = true;
212 }
213 if( !consistent ) {
214 st->print("alias_idx==%d, adr_check==", alias_idx);
215 if( adr_check == NULL ) {
216 st->print("NULL");
217 } else {
218 adr_check->dump();
219 }
220 st->cr();
221 print_alias_types();
222 assert(consistent, "adr_check must match alias idx");
223 }
224 }
225 #endif
226 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
227 // means an array I have not precisely typed yet. Do not do any
228 // alias stuff with it any time soon.
229 const TypeOopPtr *toop = tp->isa_oopptr();
230 if( tp->base() != Type::AnyPtr &&
231 !(toop &&
232 toop->klass() != NULL &&
233 toop->klass()->is_java_lang_Object() &&
234 toop->offset() == Type::OffsetBot) ) {
235 // compress paths and change unreachable cycles to TOP
236 // If not, we can update the input infinitely along a MergeMem cycle
237 // Equivalent code in PhiNode::Ideal
238 Node* m = phase->transform(mmem);
239 // If transformed to a MergeMem, get the desired slice
240 // Otherwise the returned node represents memory for every slice
241 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
242 // Update input if it is progress over what we have now
243 }
244 return mem;
245 }
246
247 //--------------------------Ideal_common---------------------------------------
248 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
249 // Unhook non-raw memories from complete (macro-expanded) initializations.
250 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
251 // If our control input is a dead region, kill all below the region
252 Node *ctl = in(MemNode::Control);
253 if (ctl && remove_dead_region(phase, can_reshape))
254 return this;
255 ctl = in(MemNode::Control);
256 // Don't bother trying to transform a dead node
257 if (ctl && ctl->is_top()) return NodeSentinel;
258
259 PhaseIterGVN *igvn = phase->is_IterGVN();
260 // Wait if control on the worklist.
261 if (ctl && can_reshape && igvn != NULL) {
262 Node* bol = NULL;
263 Node* cmp = NULL;
264 if (ctl->in(0)->is_If()) {
265 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
266 bol = ctl->in(0)->in(1);
267 if (bol->is_Bool())
268 cmp = ctl->in(0)->in(1)->in(1);
269 }
270 if (igvn->_worklist.member(ctl) ||
271 (bol != NULL && igvn->_worklist.member(bol)) ||
272 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
273 // This control path may be dead.
274 // Delay this memory node transformation until the control is processed.
275 phase->is_IterGVN()->_worklist.push(this);
276 return NodeSentinel; // caller will return NULL
277 }
278 }
279 // Ignore if memory is dead, or self-loop
280 Node *mem = in(MemNode::Memory);
281 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
282 assert(mem != this, "dead loop in MemNode::Ideal");
283
284 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
285 // This memory slice may be dead.
286 // Delay this mem node transformation until the memory is processed.
287 phase->is_IterGVN()->_worklist.push(this);
288 return NodeSentinel; // caller will return NULL
289 }
290
291 Node *address = in(MemNode::Address);
292 const Type *t_adr = phase->type(address);
293 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
294
295 if (can_reshape && igvn != NULL &&
296 (igvn->_worklist.member(address) ||
297 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
298 // The address's base and type may change when the address is processed.
299 // Delay this mem node transformation until the address is processed.
300 phase->is_IterGVN()->_worklist.push(this);
301 return NodeSentinel; // caller will return NULL
302 }
303
304 // Do NOT remove or optimize the next lines: ensure a new alias index
305 // is allocated for an oop pointer type before Escape Analysis.
306 // Note: C++ will not remove it since the call has side effect.
307 if (t_adr->isa_oopptr()) {
308 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
309 }
310
311 #ifdef ASSERT
312 Node* base = NULL;
313 if (address->is_AddP())
314 base = address->in(AddPNode::Base);
315 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
316 !t_adr->isa_rawptr()) {
317 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
318 Compile* C = phase->C;
319 tty->cr();
320 tty->print_cr("===== NULL+offs not RAW address =====");
321 if (C->is_dead_node(this->_idx)) tty->print_cr("'this' is dead");
322 if ((ctl != NULL) && C->is_dead_node(ctl->_idx)) tty->print_cr("'ctl' is dead");
323 if (C->is_dead_node(mem->_idx)) tty->print_cr("'mem' is dead");
324 if (C->is_dead_node(address->_idx)) tty->print_cr("'address' is dead");
325 if (C->is_dead_node(base->_idx)) tty->print_cr("'base' is dead");
326 tty->cr();
327 base->dump(1);
328 tty->cr();
329 this->dump(2);
330 tty->print("this->adr_type(): "); adr_type()->dump(); tty->cr();
331 tty->print("phase->type(address): "); t_adr->dump(); tty->cr();
332 tty->print("phase->type(base): "); phase->type(address)->dump(); tty->cr();
333 tty->cr();
334 }
335 assert(base == NULL || t_adr->isa_rawptr() ||
336 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
337 #endif
338
339 // Avoid independent memory operations
340 Node* old_mem = mem;
341
342 // The code which unhooks non-raw memories from complete (macro-expanded)
343 // initializations was removed. After macro-expansion all stores catched
344 // by Initialize node became raw stores and there is no information
345 // which memory slices they modify. So it is unsafe to move any memory
346 // operation above these stores. Also in most cases hooked non-raw memories
347 // were already unhooked by using information from detect_ptr_independence()
348 // and find_previous_store().
349
350 if (mem->is_MergeMem()) {
351 MergeMemNode* mmem = mem->as_MergeMem();
352 const TypePtr *tp = t_adr->is_ptr();
353
354 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
355 }
356
357 if (mem != old_mem) {
358 set_req(MemNode::Memory, mem);
359 if (can_reshape && old_mem->outcnt() == 0) {
360 igvn->_worklist.push(old_mem);
361 }
362 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
363 return this;
364 }
365
366 // let the subclass continue analyzing...
367 return NULL;
368 }
369
370 // Helper function for proving some simple control dominations.
371 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
372 // Already assumes that 'dom' is available at 'sub', and that 'sub'
373 // is not a constant (dominated by the method's StartNode).
374 // Used by MemNode::find_previous_store to prove that the
375 // control input of a memory operation predates (dominates)
376 // an allocation it wants to look past.
377 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
378 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
379 return false; // Conservative answer for dead code
380
381 // Check 'dom'. Skip Proj and CatchProj nodes.
382 dom = dom->find_exact_control(dom);
383 if (dom == NULL || dom->is_top())
384 return false; // Conservative answer for dead code
385
386 if (dom == sub) {
387 // For the case when, for example, 'sub' is Initialize and the original
388 // 'dom' is Proj node of the 'sub'.
389 return false;
390 }
391
392 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
393 return true;
394
395 // 'dom' dominates 'sub' if its control edge and control edges
396 // of all its inputs dominate or equal to sub's control edge.
397
398 // Currently 'sub' is either Allocate, Initialize or Start nodes.
399 // Or Region for the check in LoadNode::Ideal();
400 // 'sub' should have sub->in(0) != NULL.
401 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
402 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
403
404 // Get control edge of 'sub'.
405 Node* orig_sub = sub;
406 sub = sub->find_exact_control(sub->in(0));
407 if (sub == NULL || sub->is_top())
408 return false; // Conservative answer for dead code
409
410 assert(sub->is_CFG(), "expecting control");
411
412 if (sub == dom)
413 return true;
414
415 if (sub->is_Start() || sub->is_Root())
416 return false;
417
418 {
419 // Check all control edges of 'dom'.
420
421 ResourceMark rm;
422 Arena* arena = Thread::current()->resource_area();
423 Node_List nlist(arena);
424 Unique_Node_List dom_list(arena);
425
426 dom_list.push(dom);
427 bool only_dominating_controls = false;
428
429 for (uint next = 0; next < dom_list.size(); next++) {
430 Node* n = dom_list.at(next);
431 if (n == orig_sub)
432 return false; // One of dom's inputs dominated by sub.
433 if (!n->is_CFG() && n->pinned()) {
434 // Check only own control edge for pinned non-control nodes.
435 n = n->find_exact_control(n->in(0));
436 if (n == NULL || n->is_top())
437 return false; // Conservative answer for dead code
438 assert(n->is_CFG(), "expecting control");
439 dom_list.push(n);
440 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
441 only_dominating_controls = true;
442 } else if (n->is_CFG()) {
443 if (n->dominates(sub, nlist))
444 only_dominating_controls = true;
445 else
446 return false;
447 } else {
448 // First, own control edge.
449 Node* m = n->find_exact_control(n->in(0));
450 if (m != NULL) {
451 if (m->is_top())
452 return false; // Conservative answer for dead code
453 dom_list.push(m);
454 }
455 // Now, the rest of edges.
456 uint cnt = n->req();
457 for (uint i = 1; i < cnt; i++) {
458 m = n->find_exact_control(n->in(i));
459 if (m == NULL || m->is_top())
460 continue;
461 dom_list.push(m);
462 }
463 }
464 }
465 return only_dominating_controls;
466 }
467 }
468
469 //---------------------detect_ptr_independence---------------------------------
470 // Used by MemNode::find_previous_store to prove that two base
471 // pointers are never equal.
472 // The pointers are accompanied by their associated allocations,
473 // if any, which have been previously discovered by the caller.
474 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
475 Node* p2, AllocateNode* a2,
476 PhaseTransform* phase) {
477 // Attempt to prove that these two pointers cannot be aliased.
478 // They may both manifestly be allocations, and they should differ.
479 // Or, if they are not both allocations, they can be distinct constants.
480 // Otherwise, one is an allocation and the other a pre-existing value.
481 if (a1 == NULL && a2 == NULL) { // neither an allocation
482 return (p1 != p2) && p1->is_Con() && p2->is_Con();
483 } else if (a1 != NULL && a2 != NULL) { // both allocations
484 return (a1 != a2);
485 } else if (a1 != NULL) { // one allocation a1
486 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
487 return all_controls_dominate(p2, a1);
488 } else { //(a2 != NULL) // one allocation a2
489 return all_controls_dominate(p1, a2);
490 }
491 return false;
492 }
493
494
495 // The logic for reordering loads and stores uses four steps:
496 // (a) Walk carefully past stores and initializations which we
497 // can prove are independent of this load.
498 // (b) Observe that the next memory state makes an exact match
499 // with self (load or store), and locate the relevant store.
500 // (c) Ensure that, if we were to wire self directly to the store,
501 // the optimizer would fold it up somehow.
502 // (d) Do the rewiring, and return, depending on some other part of
503 // the optimizer to fold up the load.
504 // This routine handles steps (a) and (b). Steps (c) and (d) are
505 // specific to loads and stores, so they are handled by the callers.
506 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
507 //
508 Node* MemNode::find_previous_store(PhaseTransform* phase) {
509 Node* ctrl = in(MemNode::Control);
510 Node* adr = in(MemNode::Address);
511 intptr_t offset = 0;
512 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
513 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
514
515 if (offset == Type::OffsetBot)
516 return NULL; // cannot unalias unless there are precise offsets
517
518 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
519
520 intptr_t size_in_bytes = memory_size();
521
522 Node* mem = in(MemNode::Memory); // start searching here...
523
524 int cnt = 50; // Cycle limiter
525 for (;;) { // While we can dance past unrelated stores...
526 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
527
528 if (mem->is_Store()) {
529 Node* st_adr = mem->in(MemNode::Address);
530 intptr_t st_offset = 0;
531 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
532 if (st_base == NULL)
533 break; // inscrutable pointer
534 if (st_offset != offset && st_offset != Type::OffsetBot) {
535 const int MAX_STORE = BytesPerLong;
536 if (st_offset >= offset + size_in_bytes ||
537 st_offset <= offset - MAX_STORE ||
538 st_offset <= offset - mem->as_Store()->memory_size()) {
539 // Success: The offsets are provably independent.
540 // (You may ask, why not just test st_offset != offset and be done?
541 // The answer is that stores of different sizes can co-exist
542 // in the same sequence of RawMem effects. We sometimes initialize
543 // a whole 'tile' of array elements with a single jint or jlong.)
544 mem = mem->in(MemNode::Memory);
545 continue; // (a) advance through independent store memory
546 }
547 }
548 if (st_base != base &&
549 detect_ptr_independence(base, alloc,
550 st_base,
551 AllocateNode::Ideal_allocation(st_base, phase),
552 phase)) {
553 // Success: The bases are provably independent.
554 mem = mem->in(MemNode::Memory);
555 continue; // (a) advance through independent store memory
556 }
557
558 // (b) At this point, if the bases or offsets do not agree, we lose,
559 // since we have not managed to prove 'this' and 'mem' independent.
560 if (st_base == base && st_offset == offset) {
561 return mem; // let caller handle steps (c), (d)
562 }
563
564 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
565 InitializeNode* st_init = mem->in(0)->as_Initialize();
566 AllocateNode* st_alloc = st_init->allocation();
567 if (st_alloc == NULL)
568 break; // something degenerated
569 bool known_identical = false;
570 bool known_independent = false;
571 if (alloc == st_alloc)
572 known_identical = true;
573 else if (alloc != NULL)
574 known_independent = true;
575 else if (all_controls_dominate(this, st_alloc))
576 known_independent = true;
577
578 if (known_independent) {
579 // The bases are provably independent: Either they are
580 // manifestly distinct allocations, or else the control
581 // of this load dominates the store's allocation.
582 int alias_idx = phase->C->get_alias_index(adr_type());
583 if (alias_idx == Compile::AliasIdxRaw) {
584 mem = st_alloc->in(TypeFunc::Memory);
585 } else {
586 mem = st_init->memory(alias_idx);
587 }
588 continue; // (a) advance through independent store memory
589 }
590
591 // (b) at this point, if we are not looking at a store initializing
592 // the same allocation we are loading from, we lose.
593 if (known_identical) {
594 // From caller, can_see_stored_value will consult find_captured_store.
595 return mem; // let caller handle steps (c), (d)
596 }
597
598 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
599 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
600 if (mem->is_Proj() && mem->in(0)->is_Call()) {
601 CallNode *call = mem->in(0)->as_Call();
602 if (!call->may_modify(addr_t, phase)) {
603 mem = call->in(TypeFunc::Memory);
604 continue; // (a) advance through independent call memory
605 }
606 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
607 mem = mem->in(0)->in(TypeFunc::Memory);
608 continue; // (a) advance through independent MemBar memory
609 } else if (mem->is_ClearArray()) {
610 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
611 // (the call updated 'mem' value)
612 continue; // (a) advance through independent allocation memory
613 } else {
614 // Can not bypass initialization of the instance
615 // we are looking for.
616 return mem;
617 }
618 } else if (mem->is_MergeMem()) {
619 int alias_idx = phase->C->get_alias_index(adr_type());
620 mem = mem->as_MergeMem()->memory_at(alias_idx);
621 continue; // (a) advance through independent MergeMem memory
622 }
623 }
624
625 // Unless there is an explicit 'continue', we must bail out here,
626 // because 'mem' is an inscrutable memory state (e.g., a call).
627 break;
628 }
629
630 return NULL; // bail out
631 }
632
633 //----------------------calculate_adr_type-------------------------------------
634 // Helper function. Notices when the given type of address hits top or bottom.
635 // Also, asserts a cross-check of the type against the expected address type.
636 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
637 if (t == Type::TOP) return NULL; // does not touch memory any more?
638 #ifdef PRODUCT
639 cross_check = NULL;
640 #else
641 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
642 #endif
643 const TypePtr* tp = t->isa_ptr();
644 if (tp == NULL) {
645 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
646 return TypePtr::BOTTOM; // touches lots of memory
647 } else {
648 #ifdef ASSERT
649 // %%%% [phh] We don't check the alias index if cross_check is
650 // TypeRawPtr::BOTTOM. Needs to be investigated.
651 if (cross_check != NULL &&
652 cross_check != TypePtr::BOTTOM &&
653 cross_check != TypeRawPtr::BOTTOM) {
654 // Recheck the alias index, to see if it has changed (due to a bug).
655 Compile* C = Compile::current();
656 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
657 "must stay in the original alias category");
658 // The type of the address must be contained in the adr_type,
659 // disregarding "null"-ness.
660 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
661 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
662 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
663 "real address must not escape from expected memory type");
664 }
665 #endif
666 return tp;
667 }
668 }
669
670 //------------------------adr_phi_is_loop_invariant----------------------------
671 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
672 // loop is loop invariant. Make a quick traversal of Phi and associated
673 // CastPP nodes, looking to see if they are a closed group within the loop.
674 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
675 // The idea is that the phi-nest must boil down to only CastPP nodes
676 // with the same data. This implies that any path into the loop already
677 // includes such a CastPP, and so the original cast, whatever its input,
678 // must be covered by an equivalent cast, with an earlier control input.
679 ResourceMark rm;
680
681 // The loop entry input of the phi should be the unique dominating
682 // node for every Phi/CastPP in the loop.
683 Unique_Node_List closure;
684 closure.push(adr_phi->in(LoopNode::EntryControl));
685
686 // Add the phi node and the cast to the worklist.
687 Unique_Node_List worklist;
688 worklist.push(adr_phi);
689 if( cast != NULL ){
690 if( !cast->is_ConstraintCast() ) return false;
691 worklist.push(cast);
692 }
693
694 // Begin recursive walk of phi nodes.
695 while( worklist.size() ){
696 // Take a node off the worklist
697 Node *n = worklist.pop();
698 if( !closure.member(n) ){
699 // Add it to the closure.
700 closure.push(n);
701 // Make a sanity check to ensure we don't waste too much time here.
702 if( closure.size() > 20) return false;
703 // This node is OK if:
704 // - it is a cast of an identical value
705 // - or it is a phi node (then we add its inputs to the worklist)
706 // Otherwise, the node is not OK, and we presume the cast is not invariant
707 if( n->is_ConstraintCast() ){
708 worklist.push(n->in(1));
709 } else if( n->is_Phi() ) {
710 for( uint i = 1; i < n->req(); i++ ) {
711 worklist.push(n->in(i));
712 }
713 } else {
714 return false;
715 }
716 }
717 }
718
719 // Quit when the worklist is empty, and we've found no offending nodes.
720 return true;
721 }
722
723 //------------------------------Ideal_DU_postCCP-------------------------------
724 // Find any cast-away of null-ness and keep its control. Null cast-aways are
725 // going away in this pass and we need to make this memory op depend on the
726 // gating null check.
727 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
728 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
729 }
730
731 // I tried to leave the CastPP's in. This makes the graph more accurate in
732 // some sense; we get to keep around the knowledge that an oop is not-null
733 // after some test. Alas, the CastPP's interfere with GVN (some values are
734 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
735 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
736 // some of the more trivial cases in the optimizer. Removing more useless
737 // Phi's started allowing Loads to illegally float above null checks. I gave
738 // up on this approach. CNC 10/20/2000
739 // This static method may be called not from MemNode (EncodePNode calls it).
740 // Only the control edge of the node 'n' might be updated.
741 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
742 Node *skipped_cast = NULL;
743 // Need a null check? Regular static accesses do not because they are
744 // from constant addresses. Array ops are gated by the range check (which
745 // always includes a NULL check). Just check field ops.
746 if( n->in(MemNode::Control) == NULL ) {
747 // Scan upwards for the highest location we can place this memory op.
748 while( true ) {
749 switch( adr->Opcode() ) {
750
751 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
752 adr = adr->in(AddPNode::Base);
753 continue;
754
755 case Op_DecodeN: // No change to NULL-ness, so peek thru
756 case Op_DecodeNKlass:
757 adr = adr->in(1);
758 continue;
759
760 case Op_EncodeP:
761 case Op_EncodePKlass:
762 // EncodeP node's control edge could be set by this method
763 // when EncodeP node depends on CastPP node.
764 //
765 // Use its control edge for memory op because EncodeP may go away
766 // later when it is folded with following or preceding DecodeN node.
767 if (adr->in(0) == NULL) {
768 // Keep looking for cast nodes.
769 adr = adr->in(1);
770 continue;
771 }
772 ccp->hash_delete(n);
773 n->set_req(MemNode::Control, adr->in(0));
774 ccp->hash_insert(n);
775 return n;
776
777 case Op_CastPP:
778 // If the CastPP is useless, just peek on through it.
779 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
780 // Remember the cast that we've peeked though. If we peek
781 // through more than one, then we end up remembering the highest
782 // one, that is, if in a loop, the one closest to the top.
783 skipped_cast = adr;
784 adr = adr->in(1);
785 continue;
786 }
787 // CastPP is going away in this pass! We need this memory op to be
788 // control-dependent on the test that is guarding the CastPP.
789 ccp->hash_delete(n);
790 n->set_req(MemNode::Control, adr->in(0));
791 ccp->hash_insert(n);
792 return n;
793
794 case Op_Phi:
795 // Attempt to float above a Phi to some dominating point.
796 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
797 // If we've already peeked through a Cast (which could have set the
798 // control), we can't float above a Phi, because the skipped Cast
799 // may not be loop invariant.
800 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
801 adr = adr->in(1);
802 continue;
803 }
804 }
805
806 // Intentional fallthrough!
807
808 // No obvious dominating point. The mem op is pinned below the Phi
809 // by the Phi itself. If the Phi goes away (no true value is merged)
810 // then the mem op can float, but not indefinitely. It must be pinned
811 // behind the controls leading to the Phi.
812 case Op_CheckCastPP:
813 // These usually stick around to change address type, however a
814 // useless one can be elided and we still need to pick up a control edge
815 if (adr->in(0) == NULL) {
816 // This CheckCastPP node has NO control and is likely useless. But we
817 // need check further up the ancestor chain for a control input to keep
818 // the node in place. 4959717.
819 skipped_cast = adr;
820 adr = adr->in(1);
821 continue;
822 }
823 ccp->hash_delete(n);
824 n->set_req(MemNode::Control, adr->in(0));
825 ccp->hash_insert(n);
826 return n;
827
828 // List of "safe" opcodes; those that implicitly block the memory
829 // op below any null check.
830 case Op_CastX2P: // no null checks on native pointers
831 case Op_Parm: // 'this' pointer is not null
832 case Op_LoadP: // Loading from within a klass
833 case Op_LoadN: // Loading from within a klass
834 case Op_LoadKlass: // Loading from within a klass
835 case Op_LoadNKlass: // Loading from within a klass
836 case Op_ConP: // Loading from a klass
837 case Op_ConN: // Loading from a klass
838 case Op_ConNKlass: // Loading from a klass
839 case Op_CreateEx: // Sucking up the guts of an exception oop
840 case Op_Con: // Reading from TLS
841 case Op_CMoveP: // CMoveP is pinned
842 case Op_CMoveN: // CMoveN is pinned
843 break; // No progress
844
845 case Op_Proj: // Direct call to an allocation routine
846 case Op_SCMemProj: // Memory state from store conditional ops
847 #ifdef ASSERT
848 {
849 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
850 const Node* call = adr->in(0);
851 if (call->is_CallJava()) {
852 const CallJavaNode* call_java = call->as_CallJava();
853 const TypeTuple *r = call_java->tf()->range();
854 assert(r->cnt() > TypeFunc::Parms, "must return value");
855 const Type* ret_type = r->field_at(TypeFunc::Parms);
856 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
857 // We further presume that this is one of
858 // new_instance_Java, new_array_Java, or
859 // the like, but do not assert for this.
860 } else if (call->is_Allocate()) {
861 // similar case to new_instance_Java, etc.
862 } else if (!call->is_CallLeaf()) {
863 // Projections from fetch_oop (OSR) are allowed as well.
864 ShouldNotReachHere();
865 }
866 }
867 #endif
868 break;
869 default:
870 ShouldNotReachHere();
871 }
872 break;
873 }
874 }
875
876 return NULL; // No progress
877 }
878
879
880 //=============================================================================
881 uint LoadNode::size_of() const { return sizeof(*this); }
882 uint LoadNode::cmp( const Node &n ) const
883 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
884 const Type *LoadNode::bottom_type() const { return _type; }
885 uint LoadNode::ideal_reg() const {
886 return _type->ideal_reg();
887 }
888
889 #ifndef PRODUCT
890 void LoadNode::dump_spec(outputStream *st) const {
891 MemNode::dump_spec(st);
892 if( !Verbose && !WizardMode ) {
893 // standard dump does this in Verbose and WizardMode
894 st->print(" #"); _type->dump_on(st);
895 }
896 }
897 #endif
898
899 #ifdef ASSERT
900 //----------------------------is_immutable_value-------------------------------
901 // Helper function to allow a raw load without control edge for some cases
902 bool LoadNode::is_immutable_value(Node* adr) {
903 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
904 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
905 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
906 in_bytes(JavaThread::osthread_offset())));
907 }
908 #endif
909
910 //----------------------------LoadNode::make-----------------------------------
911 // Polymorphic factory method:
912 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo) {
913 Compile* C = gvn.C;
914
915 // sanity check the alias category against the created node type
916 assert(!(adr_type->isa_oopptr() &&
917 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
918 "use LoadKlassNode instead");
919 assert(!(adr_type->isa_aryptr() &&
920 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
921 "use LoadRangeNode instead");
922 // Check control edge of raw loads
923 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
924 // oop will be recorded in oop map if load crosses safepoint
925 rt->isa_oopptr() || is_immutable_value(adr),
926 "raw memory operations should have control edge");
927 switch (bt) {
928 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
929 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
930 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo);
931 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
932 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
933 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo);
934 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt, mo);
935 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt, mo);
936 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo);
937 case T_OBJECT:
938 #ifdef _LP64
939 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
940 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo));
941 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
942 } else
943 #endif
944 {
945 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
946 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo);
947 }
948 }
949 ShouldNotReachHere();
950 return (LoadNode*)NULL;
951 }
952
953 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
954 bool require_atomic = true;
955 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, require_atomic);
956 }
957
958
959
960
961 //------------------------------hash-------------------------------------------
962 uint LoadNode::hash() const {
963 // unroll addition of interesting fields
964 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
965 }
966
967 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
968 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
969 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
970 bool is_stable_ary = FoldStableValues &&
971 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
972 tp->isa_aryptr()->is_stable();
973
974 return (eliminate_boxing && non_volatile) || is_stable_ary;
975 }
976
977 return false;
978 }
979
980 //---------------------------can_see_stored_value------------------------------
981 // This routine exists to make sure this set of tests is done the same
982 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
983 // will change the graph shape in a way which makes memory alive twice at the
984 // same time (uses the Oracle model of aliasing), then some
985 // LoadXNode::Identity will fold things back to the equivalence-class model
986 // of aliasing.
987 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
988 Node* ld_adr = in(MemNode::Address);
989 intptr_t ld_off = 0;
990 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
991 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
992 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
993 // This is more general than load from boxing objects.
994 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
995 uint alias_idx = atp->index();
996 bool final = !atp->is_rewritable();
997 Node* result = NULL;
998 Node* current = st;
999 // Skip through chains of MemBarNodes checking the MergeMems for
1000 // new states for the slice of this load. Stop once any other
1001 // kind of node is encountered. Loads from final memory can skip
1002 // through any kind of MemBar but normal loads shouldn't skip
1003 // through MemBarAcquire since the could allow them to move out of
1004 // a synchronized region.
1005 while (current->is_Proj()) {
1006 int opc = current->in(0)->Opcode();
1007 if ((final && (opc == Op_MemBarAcquire ||
1008 opc == Op_MemBarAcquireLock ||
1009 opc == Op_LoadFence)) ||
1010 opc == Op_MemBarRelease ||
1011 opc == Op_StoreFence ||
1012 opc == Op_MemBarReleaseLock ||
1013 opc == Op_MemBarCPUOrder) {
1014 Node* mem = current->in(0)->in(TypeFunc::Memory);
1015 if (mem->is_MergeMem()) {
1016 MergeMemNode* merge = mem->as_MergeMem();
1017 Node* new_st = merge->memory_at(alias_idx);
1018 if (new_st == merge->base_memory()) {
1019 // Keep searching
1020 current = new_st;
1021 continue;
1022 }
1023 // Save the new memory state for the slice and fall through
1024 // to exit.
1025 result = new_st;
1026 }
1027 }
1028 break;
1029 }
1030 if (result != NULL) {
1031 st = result;
1032 }
1033 }
1034
1035 // Loop around twice in the case Load -> Initialize -> Store.
1036 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1037 for (int trip = 0; trip <= 1; trip++) {
1038
1039 if (st->is_Store()) {
1040 Node* st_adr = st->in(MemNode::Address);
1041 if (!phase->eqv(st_adr, ld_adr)) {
1042 // Try harder before giving up... Match raw and non-raw pointers.
1043 intptr_t st_off = 0;
1044 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1045 if (alloc == NULL) return NULL;
1046 if (alloc != ld_alloc) return NULL;
1047 if (ld_off != st_off) return NULL;
1048 // At this point we have proven something like this setup:
1049 // A = Allocate(...)
1050 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1051 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1052 // (Actually, we haven't yet proven the Q's are the same.)
1053 // In other words, we are loading from a casted version of
1054 // the same pointer-and-offset that we stored to.
1055 // Thus, we are able to replace L by V.
1056 }
1057 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1058 if (store_Opcode() != st->Opcode())
1059 return NULL;
1060 return st->in(MemNode::ValueIn);
1061 }
1062
1063 // A load from a freshly-created object always returns zero.
1064 // (This can happen after LoadNode::Ideal resets the load's memory input
1065 // to find_captured_store, which returned InitializeNode::zero_memory.)
1066 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1067 (st->in(0) == ld_alloc) &&
1068 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1069 // return a zero value for the load's basic type
1070 // (This is one of the few places where a generic PhaseTransform
1071 // can create new nodes. Think of it as lazily manifesting
1072 // virtually pre-existing constants.)
1073 return phase->zerocon(memory_type());
1074 }
1075
1076 // A load from an initialization barrier can match a captured store.
1077 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1078 InitializeNode* init = st->in(0)->as_Initialize();
1079 AllocateNode* alloc = init->allocation();
1080 if ((alloc != NULL) && (alloc == ld_alloc)) {
1081 // examine a captured store value
1082 st = init->find_captured_store(ld_off, memory_size(), phase);
1083 if (st != NULL)
1084 continue; // take one more trip around
1085 }
1086 }
1087
1088 // Load boxed value from result of valueOf() call is input parameter.
1089 if (this->is_Load() && ld_adr->is_AddP() &&
1090 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1091 intptr_t ignore = 0;
1092 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1093 if (base != NULL && base->is_Proj() &&
1094 base->as_Proj()->_con == TypeFunc::Parms &&
1095 base->in(0)->is_CallStaticJava() &&
1096 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1097 return base->in(0)->in(TypeFunc::Parms);
1098 }
1099 }
1100
1101 break;
1102 }
1103
1104 return NULL;
1105 }
1106
1107 //----------------------is_instance_field_load_with_local_phi------------------
1108 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1109 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1110 in(Address)->is_AddP() ) {
1111 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1112 // Only instances and boxed values.
1113 if( t_oop != NULL &&
1114 (t_oop->is_ptr_to_boxed_value() ||
1115 t_oop->is_known_instance_field()) &&
1116 t_oop->offset() != Type::OffsetBot &&
1117 t_oop->offset() != Type::OffsetTop) {
1118 return true;
1119 }
1120 }
1121 return false;
1122 }
1123
1124 //------------------------------Identity---------------------------------------
1125 // Loads are identity if previous store is to same address
1126 Node *LoadNode::Identity( PhaseTransform *phase ) {
1127 // If the previous store-maker is the right kind of Store, and the store is
1128 // to the same address, then we are equal to the value stored.
1129 Node* mem = in(Memory);
1130 Node* value = can_see_stored_value(mem, phase);
1131 if( value ) {
1132 // byte, short & char stores truncate naturally.
1133 // A load has to load the truncated value which requires
1134 // some sort of masking operation and that requires an
1135 // Ideal call instead of an Identity call.
1136 if (memory_size() < BytesPerInt) {
1137 // If the input to the store does not fit with the load's result type,
1138 // it must be truncated via an Ideal call.
1139 if (!phase->type(value)->higher_equal(phase->type(this)))
1140 return this;
1141 }
1142 // (This works even when value is a Con, but LoadNode::Value
1143 // usually runs first, producing the singleton type of the Con.)
1144 return value;
1145 }
1146
1147 // Search for an existing data phi which was generated before for the same
1148 // instance's field to avoid infinite generation of phis in a loop.
1149 Node *region = mem->in(0);
1150 if (is_instance_field_load_with_local_phi(region)) {
1151 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1152 int this_index = phase->C->get_alias_index(addr_t);
1153 int this_offset = addr_t->offset();
1154 int this_iid = addr_t->instance_id();
1155 if (!addr_t->is_known_instance() &&
1156 addr_t->is_ptr_to_boxed_value()) {
1157 // Use _idx of address base (could be Phi node) for boxed values.
1158 intptr_t ignore = 0;
1159 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1160 this_iid = base->_idx;
1161 }
1162 const Type* this_type = bottom_type();
1163 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1164 Node* phi = region->fast_out(i);
1165 if (phi->is_Phi() && phi != mem &&
1166 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1167 return phi;
1168 }
1169 }
1170 }
1171
1172 return this;
1173 }
1174
1175 // We're loading from an object which has autobox behaviour.
1176 // If this object is result of a valueOf call we'll have a phi
1177 // merging a newly allocated object and a load from the cache.
1178 // We want to replace this load with the original incoming
1179 // argument to the valueOf call.
1180 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1181 assert(phase->C->eliminate_boxing(), "sanity");
1182 intptr_t ignore = 0;
1183 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1184 if ((base == NULL) || base->is_Phi()) {
1185 // Push the loads from the phi that comes from valueOf up
1186 // through it to allow elimination of the loads and the recovery
1187 // of the original value. It is done in split_through_phi().
1188 return NULL;
1189 } else if (base->is_Load() ||
1190 base->is_DecodeN() && base->in(1)->is_Load()) {
1191 // Eliminate the load of boxed value for integer types from the cache
1192 // array by deriving the value from the index into the array.
1193 // Capture the offset of the load and then reverse the computation.
1194
1195 // Get LoadN node which loads a boxing object from 'cache' array.
1196 if (base->is_DecodeN()) {
1197 base = base->in(1);
1198 }
1199 if (!base->in(Address)->is_AddP()) {
1200 return NULL; // Complex address
1201 }
1202 AddPNode* address = base->in(Address)->as_AddP();
1203 Node* cache_base = address->in(AddPNode::Base);
1204 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1205 // Get ConP node which is static 'cache' field.
1206 cache_base = cache_base->in(1);
1207 }
1208 if ((cache_base != NULL) && cache_base->is_Con()) {
1209 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1210 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1211 Node* elements[4];
1212 int shift = exact_log2(type2aelembytes(T_OBJECT));
1213 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1214 if ((count > 0) && elements[0]->is_Con() &&
1215 ((count == 1) ||
1216 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1217 elements[1]->in(2) == phase->intcon(shift))) {
1218 ciObjArray* array = base_type->const_oop()->as_obj_array();
1219 // Fetch the box object cache[0] at the base of the array and get its value
1220 ciInstance* box = array->obj_at(0)->as_instance();
1221 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1222 assert(ik->is_box_klass(), "sanity");
1223 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1224 if (ik->nof_nonstatic_fields() == 1) {
1225 // This should be true nonstatic_field_at requires calling
1226 // nof_nonstatic_fields so check it anyway
1227 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1228 BasicType bt = c.basic_type();
1229 // Only integer types have boxing cache.
1230 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1231 bt == T_BYTE || bt == T_SHORT ||
1232 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1233 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1234 if (cache_low != (int)cache_low) {
1235 return NULL; // should not happen since cache is array indexed by value
1236 }
1237 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1238 if (offset != (int)offset) {
1239 return NULL; // should not happen since cache is array indexed by value
1240 }
1241 // Add up all the offsets making of the address of the load
1242 Node* result = elements[0];
1243 for (int i = 1; i < count; i++) {
1244 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1245 }
1246 // Remove the constant offset from the address and then
1247 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1248 // remove the scaling of the offset to recover the original index.
1249 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1250 // Peel the shift off directly but wrap it in a dummy node
1251 // since Ideal can't return existing nodes
1252 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1253 } else if (result->is_Add() && result->in(2)->is_Con() &&
1254 result->in(1)->Opcode() == Op_LShiftX &&
1255 result->in(1)->in(2) == phase->intcon(shift)) {
1256 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1257 // but for boxing cache access we know that X<<Z will not overflow
1258 // (there is range check) so we do this optimizatrion by hand here.
1259 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1260 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1261 } else {
1262 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1263 }
1264 #ifdef _LP64
1265 if (bt != T_LONG) {
1266 result = new (phase->C) ConvL2INode(phase->transform(result));
1267 }
1268 #else
1269 if (bt == T_LONG) {
1270 result = new (phase->C) ConvI2LNode(phase->transform(result));
1271 }
1272 #endif
1273 return result;
1274 }
1275 }
1276 }
1277 }
1278 }
1279 return NULL;
1280 }
1281
1282 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1283 Node* region = phi->in(0);
1284 if (region == NULL) {
1285 return false; // Wait stable graph
1286 }
1287 uint cnt = phi->req();
1288 for (uint i = 1; i < cnt; i++) {
1289 Node* rc = region->in(i);
1290 if (rc == NULL || phase->type(rc) == Type::TOP)
1291 return false; // Wait stable graph
1292 Node* in = phi->in(i);
1293 if (in == NULL || phase->type(in) == Type::TOP)
1294 return false; // Wait stable graph
1295 }
1296 return true;
1297 }
1298 //------------------------------split_through_phi------------------------------
1299 // Split instance or boxed field load through Phi.
1300 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1301 Node* mem = in(Memory);
1302 Node* address = in(Address);
1303 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1304
1305 assert((t_oop != NULL) &&
1306 (t_oop->is_known_instance_field() ||
1307 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1308
1309 Compile* C = phase->C;
1310 intptr_t ignore = 0;
1311 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1312 bool base_is_phi = (base != NULL) && base->is_Phi();
1313 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1314 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1315 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1316
1317 if (!((mem->is_Phi() || base_is_phi) &&
1318 (load_boxed_values || t_oop->is_known_instance_field()))) {
1319 return NULL; // memory is not Phi
1320 }
1321
1322 if (mem->is_Phi()) {
1323 if (!stable_phi(mem->as_Phi(), phase)) {
1324 return NULL; // Wait stable graph
1325 }
1326 uint cnt = mem->req();
1327 // Check for loop invariant memory.
1328 if (cnt == 3) {
1329 for (uint i = 1; i < cnt; i++) {
1330 Node* in = mem->in(i);
1331 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1332 if (m == mem) {
1333 set_req(Memory, mem->in(cnt - i));
1334 return this; // made change
1335 }
1336 }
1337 }
1338 }
1339 if (base_is_phi) {
1340 if (!stable_phi(base->as_Phi(), phase)) {
1341 return NULL; // Wait stable graph
1342 }
1343 uint cnt = base->req();
1344 // Check for loop invariant memory.
1345 if (cnt == 3) {
1346 for (uint i = 1; i < cnt; i++) {
1347 if (base->in(i) == base) {
1348 return NULL; // Wait stable graph
1349 }
1350 }
1351 }
1352 }
1353
1354 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1355
1356 // Split through Phi (see original code in loopopts.cpp).
1357 assert(C->have_alias_type(t_oop), "instance should have alias type");
1358
1359 // Do nothing here if Identity will find a value
1360 // (to avoid infinite chain of value phis generation).
1361 if (!phase->eqv(this, this->Identity(phase)))
1362 return NULL;
1363
1364 // Select Region to split through.
1365 Node* region;
1366 if (!base_is_phi) {
1367 assert(mem->is_Phi(), "sanity");
1368 region = mem->in(0);
1369 // Skip if the region dominates some control edge of the address.
1370 if (!MemNode::all_controls_dominate(address, region))
1371 return NULL;
1372 } else if (!mem->is_Phi()) {
1373 assert(base_is_phi, "sanity");
1374 region = base->in(0);
1375 // Skip if the region dominates some control edge of the memory.
1376 if (!MemNode::all_controls_dominate(mem, region))
1377 return NULL;
1378 } else if (base->in(0) != mem->in(0)) {
1379 assert(base_is_phi && mem->is_Phi(), "sanity");
1380 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1381 region = base->in(0);
1382 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1383 region = mem->in(0);
1384 } else {
1385 return NULL; // complex graph
1386 }
1387 } else {
1388 assert(base->in(0) == mem->in(0), "sanity");
1389 region = mem->in(0);
1390 }
1391
1392 const Type* this_type = this->bottom_type();
1393 int this_index = C->get_alias_index(t_oop);
1394 int this_offset = t_oop->offset();
1395 int this_iid = t_oop->instance_id();
1396 if (!t_oop->is_known_instance() && load_boxed_values) {
1397 // Use _idx of address base for boxed values.
1398 this_iid = base->_idx;
1399 }
1400 PhaseIterGVN* igvn = phase->is_IterGVN();
1401 Node* phi = new (C) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1402 for (uint i = 1; i < region->req(); i++) {
1403 Node* x;
1404 Node* the_clone = NULL;
1405 if (region->in(i) == C->top()) {
1406 x = C->top(); // Dead path? Use a dead data op
1407 } else {
1408 x = this->clone(); // Else clone up the data op
1409 the_clone = x; // Remember for possible deletion.
1410 // Alter data node to use pre-phi inputs
1411 if (this->in(0) == region) {
1412 x->set_req(0, region->in(i));
1413 } else {
1414 x->set_req(0, NULL);
1415 }
1416 if (mem->is_Phi() && (mem->in(0) == region)) {
1417 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1418 }
1419 if (address->is_Phi() && address->in(0) == region) {
1420 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1421 }
1422 if (base_is_phi && (base->in(0) == region)) {
1423 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1424 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1425 x->set_req(Address, adr_x);
1426 }
1427 }
1428 // Check for a 'win' on some paths
1429 const Type *t = x->Value(igvn);
1430
1431 bool singleton = t->singleton();
1432
1433 // See comments in PhaseIdealLoop::split_thru_phi().
1434 if (singleton && t == Type::TOP) {
1435 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1436 }
1437
1438 if (singleton) {
1439 x = igvn->makecon(t);
1440 } else {
1441 // We now call Identity to try to simplify the cloned node.
1442 // Note that some Identity methods call phase->type(this).
1443 // Make sure that the type array is big enough for
1444 // our new node, even though we may throw the node away.
1445 // (This tweaking with igvn only works because x is a new node.)
1446 igvn->set_type(x, t);
1447 // If x is a TypeNode, capture any more-precise type permanently into Node
1448 // otherwise it will be not updated during igvn->transform since
1449 // igvn->type(x) is set to x->Value() already.
1450 x->raise_bottom_type(t);
1451 Node *y = x->Identity(igvn);
1452 if (y != x) {
1453 x = y;
1454 } else {
1455 y = igvn->hash_find_insert(x);
1456 if (y) {
1457 x = y;
1458 } else {
1459 // Else x is a new node we are keeping
1460 // We do not need register_new_node_with_optimizer
1461 // because set_type has already been called.
1462 igvn->_worklist.push(x);
1463 }
1464 }
1465 }
1466 if (x != the_clone && the_clone != NULL) {
1467 igvn->remove_dead_node(the_clone);
1468 }
1469 phi->set_req(i, x);
1470 }
1471 // Record Phi
1472 igvn->register_new_node_with_optimizer(phi);
1473 return phi;
1474 }
1475
1476 //------------------------------Ideal------------------------------------------
1477 // If the load is from Field memory and the pointer is non-null, we can
1478 // zero out the control input.
1479 // If the offset is constant and the base is an object allocation,
1480 // try to hook me up to the exact initializing store.
1481 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1482 Node* p = MemNode::Ideal_common(phase, can_reshape);
1483 if (p) return (p == NodeSentinel) ? NULL : p;
1484
1485 Node* ctrl = in(MemNode::Control);
1486 Node* address = in(MemNode::Address);
1487
1488 // Skip up past a SafePoint control. Cannot do this for Stores because
1489 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1490 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1491 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1492 ctrl = ctrl->in(0);
1493 set_req(MemNode::Control,ctrl);
1494 }
1495
1496 intptr_t ignore = 0;
1497 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1498 if (base != NULL
1499 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1500 // Check for useless control edge in some common special cases
1501 if (in(MemNode::Control) != NULL
1502 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1503 && all_controls_dominate(base, phase->C->start())) {
1504 // A method-invariant, non-null address (constant or 'this' argument).
1505 set_req(MemNode::Control, NULL);
1506 }
1507 }
1508
1509 Node* mem = in(MemNode::Memory);
1510 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1511
1512 if (can_reshape && (addr_t != NULL)) {
1513 // try to optimize our memory input
1514 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1515 if (opt_mem != mem) {
1516 set_req(MemNode::Memory, opt_mem);
1517 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1518 return this;
1519 }
1520 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1521 if ((t_oop != NULL) &&
1522 (t_oop->is_known_instance_field() ||
1523 t_oop->is_ptr_to_boxed_value())) {
1524 PhaseIterGVN *igvn = phase->is_IterGVN();
1525 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1526 // Delay this transformation until memory Phi is processed.
1527 phase->is_IterGVN()->_worklist.push(this);
1528 return NULL;
1529 }
1530 // Split instance field load through Phi.
1531 Node* result = split_through_phi(phase);
1532 if (result != NULL) return result;
1533
1534 if (t_oop->is_ptr_to_boxed_value()) {
1535 Node* result = eliminate_autobox(phase);
1536 if (result != NULL) return result;
1537 }
1538 }
1539 }
1540
1541 // Check for prior store with a different base or offset; make Load
1542 // independent. Skip through any number of them. Bail out if the stores
1543 // are in an endless dead cycle and report no progress. This is a key
1544 // transform for Reflection. However, if after skipping through the Stores
1545 // we can't then fold up against a prior store do NOT do the transform as
1546 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1547 // array memory alive twice: once for the hoisted Load and again after the
1548 // bypassed Store. This situation only works if EVERYBODY who does
1549 // anti-dependence work knows how to bypass. I.e. we need all
1550 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1551 // the alias index stuff. So instead, peek through Stores and IFF we can
1552 // fold up, do so.
1553 Node* prev_mem = find_previous_store(phase);
1554 // Steps (a), (b): Walk past independent stores to find an exact match.
1555 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1556 // (c) See if we can fold up on the spot, but don't fold up here.
1557 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1558 // just return a prior value, which is done by Identity calls.
1559 if (can_see_stored_value(prev_mem, phase)) {
1560 // Make ready for step (d):
1561 set_req(MemNode::Memory, prev_mem);
1562 return this;
1563 }
1564 }
1565
1566 return NULL; // No further progress
1567 }
1568
1569 // Helper to recognize certain Klass fields which are invariant across
1570 // some group of array types (e.g., int[] or all T[] where T < Object).
1571 const Type*
1572 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1573 ciKlass* klass) const {
1574 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1575 // The field is Klass::_modifier_flags. Return its (constant) value.
1576 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1577 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1578 return TypeInt::make(klass->modifier_flags());
1579 }
1580 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1581 // The field is Klass::_access_flags. Return its (constant) value.
1582 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1583 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1584 return TypeInt::make(klass->access_flags());
1585 }
1586 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1587 // The field is Klass::_layout_helper. Return its constant value if known.
1588 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1589 return TypeInt::make(klass->layout_helper());
1590 }
1591
1592 // No match.
1593 return NULL;
1594 }
1595
1596 // Try to constant-fold a stable array element.
1597 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1598 assert(ary->const_oop(), "array should be constant");
1599 assert(ary->is_stable(), "array should be stable");
1600
1601 // Decode the results of GraphKit::array_element_address.
1602 ciArray* aobj = ary->const_oop()->as_array();
1603 ciConstant con = aobj->element_value_by_offset(off);
1604
1605 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1606 const Type* con_type = Type::make_from_constant(con);
1607 if (con_type != NULL) {
1608 if (con_type->isa_aryptr()) {
1609 // Join with the array element type, in case it is also stable.
1610 int dim = ary->stable_dimension();
1611 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1612 }
1613 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1614 con_type = con_type->make_narrowoop();
1615 }
1616 #ifndef PRODUCT
1617 if (TraceIterativeGVN) {
1618 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1619 con_type->dump(); tty->cr();
1620 }
1621 #endif //PRODUCT
1622 return con_type;
1623 }
1624 }
1625 return NULL;
1626 }
1627
1628 //------------------------------Value-----------------------------------------
1629 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1630 // Either input is TOP ==> the result is TOP
1631 Node* mem = in(MemNode::Memory);
1632 const Type *t1 = phase->type(mem);
1633 if (t1 == Type::TOP) return Type::TOP;
1634 Node* adr = in(MemNode::Address);
1635 const TypePtr* tp = phase->type(adr)->isa_ptr();
1636 if (tp == NULL || tp->empty()) return Type::TOP;
1637 int off = tp->offset();
1638 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1639 Compile* C = phase->C;
1640
1641 // Try to guess loaded type from pointer type
1642 if (tp->isa_aryptr()) {
1643 const TypeAryPtr* ary = tp->is_aryptr();
1644 const Type* t = ary->elem();
1645
1646 // Determine whether the reference is beyond the header or not, by comparing
1647 // the offset against the offset of the start of the array's data.
1648 // Different array types begin at slightly different offsets (12 vs. 16).
1649 // We choose T_BYTE as an example base type that is least restrictive
1650 // as to alignment, which will therefore produce the smallest
1651 // possible base offset.
1652 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1653 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1654
1655 // Try to constant-fold a stable array element.
1656 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1657 // Make sure the reference is not into the header and the offset is constant
1658 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1659 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1660 if (con_type != NULL) {
1661 return con_type;
1662 }
1663 }
1664 }
1665
1666 // Don't do this for integer types. There is only potential profit if
1667 // the element type t is lower than _type; that is, for int types, if _type is
1668 // more restrictive than t. This only happens here if one is short and the other
1669 // char (both 16 bits), and in those cases we've made an intentional decision
1670 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1671 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1672 //
1673 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1674 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1675 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1676 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1677 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1678 // In fact, that could have been the original type of p1, and p1 could have
1679 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1680 // expression (LShiftL quux 3) independently optimized to the constant 8.
1681 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1682 && (_type->isa_vect() == NULL)
1683 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1684 // t might actually be lower than _type, if _type is a unique
1685 // concrete subclass of abstract class t.
1686 if (off_beyond_header) { // is the offset beyond the header?
1687 const Type* jt = t->join_speculative(_type);
1688 // In any case, do not allow the join, per se, to empty out the type.
1689 if (jt->empty() && !t->empty()) {
1690 // This can happen if a interface-typed array narrows to a class type.
1691 jt = _type;
1692 }
1693 #ifdef ASSERT
1694 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1695 // The pointers in the autobox arrays are always non-null
1696 Node* base = adr->in(AddPNode::Base);
1697 if ((base != NULL) && base->is_DecodeN()) {
1698 // Get LoadN node which loads IntegerCache.cache field
1699 base = base->in(1);
1700 }
1701 if ((base != NULL) && base->is_Con()) {
1702 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1703 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1704 // It could be narrow oop
1705 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1706 }
1707 }
1708 }
1709 #endif
1710 return jt;
1711 }
1712 }
1713 } else if (tp->base() == Type::InstPtr) {
1714 ciEnv* env = C->env();
1715 const TypeInstPtr* tinst = tp->is_instptr();
1716 ciKlass* klass = tinst->klass();
1717 assert( off != Type::OffsetBot ||
1718 // arrays can be cast to Objects
1719 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1720 // unsafe field access may not have a constant offset
1721 C->has_unsafe_access(),
1722 "Field accesses must be precise" );
1723 // For oop loads, we expect the _type to be precise
1724 if (klass == env->String_klass() &&
1725 adr->is_AddP() && off != Type::OffsetBot) {
1726 // For constant Strings treat the final fields as compile time constants.
1727 Node* base = adr->in(AddPNode::Base);
1728 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1729 if (t != NULL && t->singleton()) {
1730 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1731 if (field != NULL && field->is_final()) {
1732 ciObject* string = t->const_oop();
1733 ciConstant constant = string->as_instance()->field_value(field);
1734 if (constant.basic_type() == T_INT) {
1735 return TypeInt::make(constant.as_int());
1736 } else if (constant.basic_type() == T_ARRAY) {
1737 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1738 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1739 } else {
1740 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1741 }
1742 }
1743 }
1744 }
1745 }
1746 // Optimizations for constant objects
1747 ciObject* const_oop = tinst->const_oop();
1748 if (const_oop != NULL) {
1749 // For constant Boxed value treat the target field as a compile time constant.
1750 if (tinst->is_ptr_to_boxed_value()) {
1751 return tinst->get_const_boxed_value();
1752 } else
1753 // For constant CallSites treat the target field as a compile time constant.
1754 if (const_oop->is_call_site()) {
1755 ciCallSite* call_site = const_oop->as_call_site();
1756 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1757 if (field != NULL && field->is_call_site_target()) {
1758 ciMethodHandle* target = call_site->get_target();
1759 if (target != NULL) { // just in case
1760 ciConstant constant(T_OBJECT, target);
1761 const Type* t;
1762 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1763 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1764 } else {
1765 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1766 }
1767 // Add a dependence for invalidation of the optimization.
1768 if (!call_site->is_constant_call_site()) {
1769 C->dependencies()->assert_call_site_target_value(call_site, target);
1770 }
1771 return t;
1772 }
1773 }
1774 }
1775 }
1776 } else if (tp->base() == Type::KlassPtr) {
1777 assert( off != Type::OffsetBot ||
1778 // arrays can be cast to Objects
1779 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1780 // also allow array-loading from the primary supertype
1781 // array during subtype checks
1782 Opcode() == Op_LoadKlass,
1783 "Field accesses must be precise" );
1784 // For klass/static loads, we expect the _type to be precise
1785 }
1786
1787 const TypeKlassPtr *tkls = tp->isa_klassptr();
1788 if (tkls != NULL && !StressReflectiveCode) {
1789 ciKlass* klass = tkls->klass();
1790 if (klass->is_loaded() && tkls->klass_is_exact()) {
1791 // We are loading a field from a Klass metaobject whose identity
1792 // is known at compile time (the type is "exact" or "precise").
1793 // Check for fields we know are maintained as constants by the VM.
1794 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1795 // The field is Klass::_super_check_offset. Return its (constant) value.
1796 // (Folds up type checking code.)
1797 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1798 return TypeInt::make(klass->super_check_offset());
1799 }
1800 // Compute index into primary_supers array
1801 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1802 // Check for overflowing; use unsigned compare to handle the negative case.
1803 if( depth < ciKlass::primary_super_limit() ) {
1804 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1805 // (Folds up type checking code.)
1806 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1807 ciKlass *ss = klass->super_of_depth(depth);
1808 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1809 }
1810 const Type* aift = load_array_final_field(tkls, klass);
1811 if (aift != NULL) return aift;
1812 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1813 && klass->is_array_klass()) {
1814 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1815 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1816 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1817 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1818 }
1819 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1820 // The field is Klass::_java_mirror. Return its (constant) value.
1821 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1822 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1823 return TypeInstPtr::make(klass->java_mirror());
1824 }
1825 }
1826
1827 // We can still check if we are loading from the primary_supers array at a
1828 // shallow enough depth. Even though the klass is not exact, entries less
1829 // than or equal to its super depth are correct.
1830 if (klass->is_loaded() ) {
1831 ciType *inner = klass;
1832 while( inner->is_obj_array_klass() )
1833 inner = inner->as_obj_array_klass()->base_element_type();
1834 if( inner->is_instance_klass() &&
1835 !inner->as_instance_klass()->flags().is_interface() ) {
1836 // Compute index into primary_supers array
1837 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1838 // Check for overflowing; use unsigned compare to handle the negative case.
1839 if( depth < ciKlass::primary_super_limit() &&
1840 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1841 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1842 // (Folds up type checking code.)
1843 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1844 ciKlass *ss = klass->super_of_depth(depth);
1845 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1846 }
1847 }
1848 }
1849
1850 // If the type is enough to determine that the thing is not an array,
1851 // we can give the layout_helper a positive interval type.
1852 // This will help short-circuit some reflective code.
1853 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1854 && !klass->is_array_klass() // not directly typed as an array
1855 && !klass->is_interface() // specifically not Serializable & Cloneable
1856 && !klass->is_java_lang_Object() // not the supertype of all T[]
1857 ) {
1858 // Note: When interfaces are reliable, we can narrow the interface
1859 // test to (klass != Serializable && klass != Cloneable).
1860 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1861 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1862 // The key property of this type is that it folds up tests
1863 // for array-ness, since it proves that the layout_helper is positive.
1864 // Thus, a generic value like the basic object layout helper works fine.
1865 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1866 }
1867 }
1868
1869 // If we are loading from a freshly-allocated object, produce a zero,
1870 // if the load is provably beyond the header of the object.
1871 // (Also allow a variable load from a fresh array to produce zero.)
1872 const TypeOopPtr *tinst = tp->isa_oopptr();
1873 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1874 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1875 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1876 Node* value = can_see_stored_value(mem,phase);
1877 if (value != NULL && value->is_Con()) {
1878 assert(value->bottom_type()->higher_equal(_type),"sanity");
1879 return value->bottom_type();
1880 }
1881 }
1882
1883 if (is_instance) {
1884 // If we have an instance type and our memory input is the
1885 // programs's initial memory state, there is no matching store,
1886 // so just return a zero of the appropriate type
1887 Node *mem = in(MemNode::Memory);
1888 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1889 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1890 return Type::get_zero_type(_type->basic_type());
1891 }
1892 }
1893 return _type;
1894 }
1895
1896 //------------------------------match_edge-------------------------------------
1897 // Do we Match on this edge index or not? Match only the address.
1898 uint LoadNode::match_edge(uint idx) const {
1899 return idx == MemNode::Address;
1900 }
1901
1902 //--------------------------LoadBNode::Ideal--------------------------------------
1903 //
1904 // If the previous store is to the same address as this load,
1905 // and the value stored was larger than a byte, replace this load
1906 // with the value stored truncated to a byte. If no truncation is
1907 // needed, the replacement is done in LoadNode::Identity().
1908 //
1909 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1910 Node* mem = in(MemNode::Memory);
1911 Node* value = can_see_stored_value(mem,phase);
1912 if( value && !phase->type(value)->higher_equal( _type ) ) {
1913 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1914 return new (phase->C) RShiftINode(result, phase->intcon(24));
1915 }
1916 // Identity call will handle the case where truncation is not needed.
1917 return LoadNode::Ideal(phase, can_reshape);
1918 }
1919
1920 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1921 Node* mem = in(MemNode::Memory);
1922 Node* value = can_see_stored_value(mem,phase);
1923 if (value != NULL && value->is_Con() &&
1924 !value->bottom_type()->higher_equal(_type)) {
1925 // If the input to the store does not fit with the load's result type,
1926 // it must be truncated. We can't delay until Ideal call since
1927 // a singleton Value is needed for split_thru_phi optimization.
1928 int con = value->get_int();
1929 return TypeInt::make((con << 24) >> 24);
1930 }
1931 return LoadNode::Value(phase);
1932 }
1933
1934 //--------------------------LoadUBNode::Ideal-------------------------------------
1935 //
1936 // If the previous store is to the same address as this load,
1937 // and the value stored was larger than a byte, replace this load
1938 // with the value stored truncated to a byte. If no truncation is
1939 // needed, the replacement is done in LoadNode::Identity().
1940 //
1941 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1942 Node* mem = in(MemNode::Memory);
1943 Node* value = can_see_stored_value(mem, phase);
1944 if (value && !phase->type(value)->higher_equal(_type))
1945 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1946 // Identity call will handle the case where truncation is not needed.
1947 return LoadNode::Ideal(phase, can_reshape);
1948 }
1949
1950 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1951 Node* mem = in(MemNode::Memory);
1952 Node* value = can_see_stored_value(mem,phase);
1953 if (value != NULL && value->is_Con() &&
1954 !value->bottom_type()->higher_equal(_type)) {
1955 // If the input to the store does not fit with the load's result type,
1956 // it must be truncated. We can't delay until Ideal call since
1957 // a singleton Value is needed for split_thru_phi optimization.
1958 int con = value->get_int();
1959 return TypeInt::make(con & 0xFF);
1960 }
1961 return LoadNode::Value(phase);
1962 }
1963
1964 //--------------------------LoadUSNode::Ideal-------------------------------------
1965 //
1966 // If the previous store is to the same address as this load,
1967 // and the value stored was larger than a char, replace this load
1968 // with the value stored truncated to a char. If no truncation is
1969 // needed, the replacement is done in LoadNode::Identity().
1970 //
1971 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1972 Node* mem = in(MemNode::Memory);
1973 Node* value = can_see_stored_value(mem,phase);
1974 if( value && !phase->type(value)->higher_equal( _type ) )
1975 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1976 // Identity call will handle the case where truncation is not needed.
1977 return LoadNode::Ideal(phase, can_reshape);
1978 }
1979
1980 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1981 Node* mem = in(MemNode::Memory);
1982 Node* value = can_see_stored_value(mem,phase);
1983 if (value != NULL && value->is_Con() &&
1984 !value->bottom_type()->higher_equal(_type)) {
1985 // If the input to the store does not fit with the load's result type,
1986 // it must be truncated. We can't delay until Ideal call since
1987 // a singleton Value is needed for split_thru_phi optimization.
1988 int con = value->get_int();
1989 return TypeInt::make(con & 0xFFFF);
1990 }
1991 return LoadNode::Value(phase);
1992 }
1993
1994 //--------------------------LoadSNode::Ideal--------------------------------------
1995 //
1996 // If the previous store is to the same address as this load,
1997 // and the value stored was larger than a short, replace this load
1998 // with the value stored truncated to a short. If no truncation is
1999 // needed, the replacement is done in LoadNode::Identity().
2000 //
2001 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2002 Node* mem = in(MemNode::Memory);
2003 Node* value = can_see_stored_value(mem,phase);
2004 if( value && !phase->type(value)->higher_equal( _type ) ) {
2005 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
2006 return new (phase->C) RShiftINode(result, phase->intcon(16));
2007 }
2008 // Identity call will handle the case where truncation is not needed.
2009 return LoadNode::Ideal(phase, can_reshape);
2010 }
2011
2012 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2013 Node* mem = in(MemNode::Memory);
2014 Node* value = can_see_stored_value(mem,phase);
2015 if (value != NULL && value->is_Con() &&
2016 !value->bottom_type()->higher_equal(_type)) {
2017 // If the input to the store does not fit with the load's result type,
2018 // it must be truncated. We can't delay until Ideal call since
2019 // a singleton Value is needed for split_thru_phi optimization.
2020 int con = value->get_int();
2021 return TypeInt::make((con << 16) >> 16);
2022 }
2023 return LoadNode::Value(phase);
2024 }
2025
2026 //=============================================================================
2027 //----------------------------LoadKlassNode::make------------------------------
2028 // Polymorphic factory method:
2029 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
2030 Compile* C = gvn.C;
2031 Node *ctl = NULL;
2032 // sanity check the alias category against the created node type
2033 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2034 assert(adr_type != NULL, "expecting TypeKlassPtr");
2035 #ifdef _LP64
2036 if (adr_type->is_ptr_to_narrowklass()) {
2037 assert(UseCompressedClassPointers, "no compressed klasses");
2038 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2039 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2040 }
2041 #endif
2042 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2043 return new (C) LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2044 }
2045
2046 //------------------------------Value------------------------------------------
2047 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2048 return klass_value_common(phase);
2049 }
2050
2051 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2052 // Either input is TOP ==> the result is TOP
2053 const Type *t1 = phase->type( in(MemNode::Memory) );
2054 if (t1 == Type::TOP) return Type::TOP;
2055 Node *adr = in(MemNode::Address);
2056 const Type *t2 = phase->type( adr );
2057 if (t2 == Type::TOP) return Type::TOP;
2058 const TypePtr *tp = t2->is_ptr();
2059 if (TypePtr::above_centerline(tp->ptr()) ||
2060 tp->ptr() == TypePtr::Null) return Type::TOP;
2061
2062 // Return a more precise klass, if possible
2063 const TypeInstPtr *tinst = tp->isa_instptr();
2064 if (tinst != NULL) {
2065 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2066 int offset = tinst->offset();
2067 if (ik == phase->C->env()->Class_klass()
2068 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2069 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2070 // We are loading a special hidden field from a Class mirror object,
2071 // the field which points to the VM's Klass metaobject.
2072 ciType* t = tinst->java_mirror_type();
2073 // java_mirror_type returns non-null for compile-time Class constants.
2074 if (t != NULL) {
2075 // constant oop => constant klass
2076 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2077 if (t->is_void()) {
2078 // We cannot create a void array. Since void is a primitive type return null
2079 // klass. Users of this result need to do a null check on the returned klass.
2080 return TypePtr::NULL_PTR;
2081 }
2082 return TypeKlassPtr::make(ciArrayKlass::make(t));
2083 }
2084 if (!t->is_klass()) {
2085 // a primitive Class (e.g., int.class) has NULL for a klass field
2086 return TypePtr::NULL_PTR;
2087 }
2088 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2089 return TypeKlassPtr::make(t->as_klass());
2090 }
2091 // non-constant mirror, so we can't tell what's going on
2092 }
2093 if( !ik->is_loaded() )
2094 return _type; // Bail out if not loaded
2095 if (offset == oopDesc::klass_offset_in_bytes()) {
2096 if (tinst->klass_is_exact()) {
2097 return TypeKlassPtr::make(ik);
2098 }
2099 // See if we can become precise: no subklasses and no interface
2100 // (Note: We need to support verified interfaces.)
2101 if (!ik->is_interface() && !ik->has_subklass()) {
2102 //assert(!UseExactTypes, "this code should be useless with exact types");
2103 // Add a dependence; if any subclass added we need to recompile
2104 if (!ik->is_final()) {
2105 // %%% should use stronger assert_unique_concrete_subtype instead
2106 phase->C->dependencies()->assert_leaf_type(ik);
2107 }
2108 // Return precise klass
2109 return TypeKlassPtr::make(ik);
2110 }
2111
2112 // Return root of possible klass
2113 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2114 }
2115 }
2116
2117 // Check for loading klass from an array
2118 const TypeAryPtr *tary = tp->isa_aryptr();
2119 if( tary != NULL ) {
2120 ciKlass *tary_klass = tary->klass();
2121 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2122 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2123 if (tary->klass_is_exact()) {
2124 return TypeKlassPtr::make(tary_klass);
2125 }
2126 ciArrayKlass *ak = tary->klass()->as_array_klass();
2127 // If the klass is an object array, we defer the question to the
2128 // array component klass.
2129 if( ak->is_obj_array_klass() ) {
2130 assert( ak->is_loaded(), "" );
2131 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2132 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2133 ciInstanceKlass* ik = base_k->as_instance_klass();
2134 // See if we can become precise: no subklasses and no interface
2135 if (!ik->is_interface() && !ik->has_subklass()) {
2136 //assert(!UseExactTypes, "this code should be useless with exact types");
2137 // Add a dependence; if any subclass added we need to recompile
2138 if (!ik->is_final()) {
2139 phase->C->dependencies()->assert_leaf_type(ik);
2140 }
2141 // Return precise array klass
2142 return TypeKlassPtr::make(ak);
2143 }
2144 }
2145 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2146 } else { // Found a type-array?
2147 //assert(!UseExactTypes, "this code should be useless with exact types");
2148 assert( ak->is_type_array_klass(), "" );
2149 return TypeKlassPtr::make(ak); // These are always precise
2150 }
2151 }
2152 }
2153
2154 // Check for loading klass from an array klass
2155 const TypeKlassPtr *tkls = tp->isa_klassptr();
2156 if (tkls != NULL && !StressReflectiveCode) {
2157 ciKlass* klass = tkls->klass();
2158 if( !klass->is_loaded() )
2159 return _type; // Bail out if not loaded
2160 if( klass->is_obj_array_klass() &&
2161 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2162 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2163 // // Always returning precise element type is incorrect,
2164 // // e.g., element type could be object and array may contain strings
2165 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2166
2167 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2168 // according to the element type's subclassing.
2169 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2170 }
2171 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2172 tkls->offset() == in_bytes(Klass::super_offset())) {
2173 ciKlass* sup = klass->as_instance_klass()->super();
2174 // The field is Klass::_super. Return its (constant) value.
2175 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2176 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2177 }
2178 }
2179
2180 // Bailout case
2181 return LoadNode::Value(phase);
2182 }
2183
2184 //------------------------------Identity---------------------------------------
2185 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2186 // Also feed through the klass in Allocate(...klass...)._klass.
2187 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2188 return klass_identity_common(phase);
2189 }
2190
2191 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2192 Node* x = LoadNode::Identity(phase);
2193 if (x != this) return x;
2194
2195 // Take apart the address into an oop and and offset.
2196 // Return 'this' if we cannot.
2197 Node* adr = in(MemNode::Address);
2198 intptr_t offset = 0;
2199 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2200 if (base == NULL) return this;
2201 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2202 if (toop == NULL) return this;
2203
2204 // We can fetch the klass directly through an AllocateNode.
2205 // This works even if the klass is not constant (clone or newArray).
2206 if (offset == oopDesc::klass_offset_in_bytes()) {
2207 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2208 if (allocated_klass != NULL) {
2209 return allocated_klass;
2210 }
2211 }
2212
2213 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2214 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2215 // See inline_native_Class_query for occurrences of these patterns.
2216 // Java Example: x.getClass().isAssignableFrom(y)
2217 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2218 //
2219 // This improves reflective code, often making the Class
2220 // mirror go completely dead. (Current exception: Class
2221 // mirrors may appear in debug info, but we could clean them out by
2222 // introducing a new debug info operator for Klass*.java_mirror).
2223 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2224 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2225 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2226 // We are loading a special hidden field from a Class mirror,
2227 // the field which points to its Klass or ArrayKlass metaobject.
2228 if (base->is_Load()) {
2229 Node* adr2 = base->in(MemNode::Address);
2230 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2231 if (tkls != NULL && !tkls->empty()
2232 && (tkls->klass()->is_instance_klass() ||
2233 tkls->klass()->is_array_klass())
2234 && adr2->is_AddP()
2235 ) {
2236 int mirror_field = in_bytes(Klass::java_mirror_offset());
2237 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2238 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2239 }
2240 if (tkls->offset() == mirror_field) {
2241 return adr2->in(AddPNode::Base);
2242 }
2243 }
2244 }
2245 }
2246
2247 return this;
2248 }
2249
2250
2251 //------------------------------Value------------------------------------------
2252 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2253 const Type *t = klass_value_common(phase);
2254 if (t == Type::TOP)
2255 return t;
2256
2257 return t->make_narrowklass();
2258 }
2259
2260 //------------------------------Identity---------------------------------------
2261 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2262 // Also feed through the klass in Allocate(...klass...)._klass.
2263 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2264 Node *x = klass_identity_common(phase);
2265
2266 const Type *t = phase->type( x );
2267 if( t == Type::TOP ) return x;
2268 if( t->isa_narrowklass()) return x;
2269 assert (!t->isa_narrowoop(), "no narrow oop here");
2270
2271 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2272 }
2273
2274 //------------------------------Value-----------------------------------------
2275 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2276 // Either input is TOP ==> the result is TOP
2277 const Type *t1 = phase->type( in(MemNode::Memory) );
2278 if( t1 == Type::TOP ) return Type::TOP;
2279 Node *adr = in(MemNode::Address);
2280 const Type *t2 = phase->type( adr );
2281 if( t2 == Type::TOP ) return Type::TOP;
2282 const TypePtr *tp = t2->is_ptr();
2283 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2284 const TypeAryPtr *tap = tp->isa_aryptr();
2285 if( !tap ) return _type;
2286 return tap->size();
2287 }
2288
2289 //-------------------------------Ideal---------------------------------------
2290 // Feed through the length in AllocateArray(...length...)._length.
2291 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2292 Node* p = MemNode::Ideal_common(phase, can_reshape);
2293 if (p) return (p == NodeSentinel) ? NULL : p;
2294
2295 // Take apart the address into an oop and and offset.
2296 // Return 'this' if we cannot.
2297 Node* adr = in(MemNode::Address);
2298 intptr_t offset = 0;
2299 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2300 if (base == NULL) return NULL;
2301 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2302 if (tary == NULL) return NULL;
2303
2304 // We can fetch the length directly through an AllocateArrayNode.
2305 // This works even if the length is not constant (clone or newArray).
2306 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2307 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2308 if (alloc != NULL) {
2309 Node* allocated_length = alloc->Ideal_length();
2310 Node* len = alloc->make_ideal_length(tary, phase);
2311 if (allocated_length != len) {
2312 // New CastII improves on this.
2313 return len;
2314 }
2315 }
2316 }
2317
2318 return NULL;
2319 }
2320
2321 //------------------------------Identity---------------------------------------
2322 // Feed through the length in AllocateArray(...length...)._length.
2323 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2324 Node* x = LoadINode::Identity(phase);
2325 if (x != this) return x;
2326
2327 // Take apart the address into an oop and and offset.
2328 // Return 'this' if we cannot.
2329 Node* adr = in(MemNode::Address);
2330 intptr_t offset = 0;
2331 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2332 if (base == NULL) return this;
2333 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2334 if (tary == NULL) return this;
2335
2336 // We can fetch the length directly through an AllocateArrayNode.
2337 // This works even if the length is not constant (clone or newArray).
2338 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2339 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2340 if (alloc != NULL) {
2341 Node* allocated_length = alloc->Ideal_length();
2342 // Do not allow make_ideal_length to allocate a CastII node.
2343 Node* len = alloc->make_ideal_length(tary, phase, false);
2344 if (allocated_length == len) {
2345 // Return allocated_length only if it would not be improved by a CastII.
2346 return allocated_length;
2347 }
2348 }
2349 }
2350
2351 return this;
2352
2353 }
2354
2355 //=============================================================================
2356 //---------------------------StoreNode::make-----------------------------------
2357 // Polymorphic factory method:
2358 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2359 assert((mo == unordered || mo == release), "unexpected");
2360 Compile* C = gvn.C;
2361 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2362 ctl != NULL, "raw memory operations should have control edge");
2363
2364 switch (bt) {
2365 case T_BOOLEAN:
2366 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val, mo);
2367 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val, mo);
2368 case T_CHAR:
2369 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val, mo);
2370 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo);
2371 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val, mo);
2372 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo);
2373 case T_METADATA:
2374 case T_ADDRESS:
2375 case T_OBJECT:
2376 #ifdef _LP64
2377 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2378 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2379 return new (C) StoreNNode(ctl, mem, adr, adr_type, val, mo);
2380 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2381 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2382 adr->bottom_type()->isa_rawptr())) {
2383 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2384 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2385 }
2386 #endif
2387 {
2388 return new (C) StorePNode(ctl, mem, adr, adr_type, val, mo);
2389 }
2390 }
2391 ShouldNotReachHere();
2392 return (StoreNode*)NULL;
2393 }
2394
2395 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2396 bool require_atomic = true;
2397 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2398 }
2399
2400
2401 //--------------------------bottom_type----------------------------------------
2402 const Type *StoreNode::bottom_type() const {
2403 return Type::MEMORY;
2404 }
2405
2406 //------------------------------hash-------------------------------------------
2407 uint StoreNode::hash() const {
2408 // unroll addition of interesting fields
2409 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2410
2411 // Since they are not commoned, do not hash them:
2412 return NO_HASH;
2413 }
2414
2415 //------------------------------Ideal------------------------------------------
2416 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2417 // When a store immediately follows a relevant allocation/initialization,
2418 // try to capture it into the initialization, or hoist it above.
2419 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2420 Node* p = MemNode::Ideal_common(phase, can_reshape);
2421 if (p) return (p == NodeSentinel) ? NULL : p;
2422
2423 Node* mem = in(MemNode::Memory);
2424 Node* address = in(MemNode::Address);
2425
2426 // Back-to-back stores to same address? Fold em up. Generally
2427 // unsafe if I have intervening uses... Also disallowed for StoreCM
2428 // since they must follow each StoreP operation. Redundant StoreCMs
2429 // are eliminated just before matching in final_graph_reshape.
2430 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2431 mem->Opcode() != Op_StoreCM) {
2432 // Looking at a dead closed cycle of memory?
2433 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2434
2435 assert(Opcode() == mem->Opcode() ||
2436 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2437 "no mismatched stores, except on raw memory");
2438
2439 if (mem->outcnt() == 1 && // check for intervening uses
2440 mem->as_Store()->memory_size() <= this->memory_size()) {
2441 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2442 // For example, 'mem' might be the final state at a conditional return.
2443 // Or, 'mem' might be used by some node which is live at the same time
2444 // 'this' is live, which might be unschedulable. So, require exactly
2445 // ONE user, the 'this' store, until such time as we clone 'mem' for
2446 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2447 if (can_reshape) { // (%%% is this an anachronism?)
2448 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2449 phase->is_IterGVN());
2450 } else {
2451 // It's OK to do this in the parser, since DU info is always accurate,
2452 // and the parser always refers to nodes via SafePointNode maps.
2453 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2454 }
2455 return this;
2456 }
2457 }
2458
2459 // Capture an unaliased, unconditional, simple store into an initializer.
2460 // Or, if it is independent of the allocation, hoist it above the allocation.
2461 if (ReduceFieldZeroing && /*can_reshape &&*/
2462 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2463 InitializeNode* init = mem->in(0)->as_Initialize();
2464 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2465 if (offset > 0) {
2466 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2467 // If the InitializeNode captured me, it made a raw copy of me,
2468 // and I need to disappear.
2469 if (moved != NULL) {
2470 // %%% hack to ensure that Ideal returns a new node:
2471 mem = MergeMemNode::make(phase->C, mem);
2472 return mem; // fold me away
2473 }
2474 }
2475 }
2476
2477 return NULL; // No further progress
2478 }
2479
2480 //------------------------------Value-----------------------------------------
2481 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2482 // Either input is TOP ==> the result is TOP
2483 const Type *t1 = phase->type( in(MemNode::Memory) );
2484 if( t1 == Type::TOP ) return Type::TOP;
2485 const Type *t2 = phase->type( in(MemNode::Address) );
2486 if( t2 == Type::TOP ) return Type::TOP;
2487 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2488 if( t3 == Type::TOP ) return Type::TOP;
2489 return Type::MEMORY;
2490 }
2491
2492 //------------------------------Identity---------------------------------------
2493 // Remove redundant stores:
2494 // Store(m, p, Load(m, p)) changes to m.
2495 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2496 Node *StoreNode::Identity( PhaseTransform *phase ) {
2497 Node* mem = in(MemNode::Memory);
2498 Node* adr = in(MemNode::Address);
2499 Node* val = in(MemNode::ValueIn);
2500
2501 // Load then Store? Then the Store is useless
2502 if (val->is_Load() &&
2503 val->in(MemNode::Address)->eqv_uncast(adr) &&
2504 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2505 val->as_Load()->store_Opcode() == Opcode()) {
2506 return mem;
2507 }
2508
2509 // Two stores in a row of the same value?
2510 if (mem->is_Store() &&
2511 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2512 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2513 mem->Opcode() == Opcode()) {
2514 return mem;
2515 }
2516
2517 // Store of zero anywhere into a freshly-allocated object?
2518 // Then the store is useless.
2519 // (It must already have been captured by the InitializeNode.)
2520 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2521 // a newly allocated object is already all-zeroes everywhere
2522 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2523 return mem;
2524 }
2525
2526 // the store may also apply to zero-bits in an earlier object
2527 Node* prev_mem = find_previous_store(phase);
2528 // Steps (a), (b): Walk past independent stores to find an exact match.
2529 if (prev_mem != NULL) {
2530 Node* prev_val = can_see_stored_value(prev_mem, phase);
2531 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2532 // prev_val and val might differ by a cast; it would be good
2533 // to keep the more informative of the two.
2534 return mem;
2535 }
2536 }
2537 }
2538
2539 return this;
2540 }
2541
2542 //------------------------------match_edge-------------------------------------
2543 // Do we Match on this edge index or not? Match only memory & value
2544 uint StoreNode::match_edge(uint idx) const {
2545 return idx == MemNode::Address || idx == MemNode::ValueIn;
2546 }
2547
2548 //------------------------------cmp--------------------------------------------
2549 // Do not common stores up together. They generally have to be split
2550 // back up anyways, so do not bother.
2551 uint StoreNode::cmp( const Node &n ) const {
2552 return (&n == this); // Always fail except on self
2553 }
2554
2555 //------------------------------Ideal_masked_input-----------------------------
2556 // Check for a useless mask before a partial-word store
2557 // (StoreB ... (AndI valIn conIa) )
2558 // If (conIa & mask == mask) this simplifies to
2559 // (StoreB ... (valIn) )
2560 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2561 Node *val = in(MemNode::ValueIn);
2562 if( val->Opcode() == Op_AndI ) {
2563 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2564 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2565 set_req(MemNode::ValueIn, val->in(1));
2566 return this;
2567 }
2568 }
2569 return NULL;
2570 }
2571
2572
2573 //------------------------------Ideal_sign_extended_input----------------------
2574 // Check for useless sign-extension before a partial-word store
2575 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2576 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2577 // (StoreB ... (valIn) )
2578 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2579 Node *val = in(MemNode::ValueIn);
2580 if( val->Opcode() == Op_RShiftI ) {
2581 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2582 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2583 Node *shl = val->in(1);
2584 if( shl->Opcode() == Op_LShiftI ) {
2585 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2586 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2587 set_req(MemNode::ValueIn, shl->in(1));
2588 return this;
2589 }
2590 }
2591 }
2592 }
2593 return NULL;
2594 }
2595
2596 //------------------------------value_never_loaded-----------------------------------
2597 // Determine whether there are any possible loads of the value stored.
2598 // For simplicity, we actually check if there are any loads from the
2599 // address stored to, not just for loads of the value stored by this node.
2600 //
2601 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2602 Node *adr = in(Address);
2603 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2604 if (adr_oop == NULL)
2605 return false;
2606 if (!adr_oop->is_known_instance_field())
2607 return false; // if not a distinct instance, there may be aliases of the address
2608 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2609 Node *use = adr->fast_out(i);
2610 int opc = use->Opcode();
2611 if (use->is_Load() || use->is_LoadStore()) {
2612 return false;
2613 }
2614 }
2615 return true;
2616 }
2617
2618 //=============================================================================
2619 //------------------------------Ideal------------------------------------------
2620 // If the store is from an AND mask that leaves the low bits untouched, then
2621 // we can skip the AND operation. If the store is from a sign-extension
2622 // (a left shift, then right shift) we can skip both.
2623 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2624 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2625 if( progress != NULL ) return progress;
2626
2627 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2628 if( progress != NULL ) return progress;
2629
2630 // Finally check the default case
2631 return StoreNode::Ideal(phase, can_reshape);
2632 }
2633
2634 //=============================================================================
2635 //------------------------------Ideal------------------------------------------
2636 // If the store is from an AND mask that leaves the low bits untouched, then
2637 // we can skip the AND operation
2638 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2639 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2640 if( progress != NULL ) return progress;
2641
2642 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2643 if( progress != NULL ) return progress;
2644
2645 // Finally check the default case
2646 return StoreNode::Ideal(phase, can_reshape);
2647 }
2648
2649 //=============================================================================
2650 //------------------------------Identity---------------------------------------
2651 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2652 // No need to card mark when storing a null ptr
2653 Node* my_store = in(MemNode::OopStore);
2654 if (my_store->is_Store()) {
2655 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2656 if( t1 == TypePtr::NULL_PTR ) {
2657 return in(MemNode::Memory);
2658 }
2659 }
2660 return this;
2661 }
2662
2663 //=============================================================================
2664 //------------------------------Ideal---------------------------------------
2665 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2666 Node* progress = StoreNode::Ideal(phase, can_reshape);
2667 if (progress != NULL) return progress;
2668
2669 Node* my_store = in(MemNode::OopStore);
2670 if (my_store->is_MergeMem()) {
2671 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2672 set_req(MemNode::OopStore, mem);
2673 return this;
2674 }
2675
2676 return NULL;
2677 }
2678
2679 //------------------------------Value-----------------------------------------
2680 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2681 // Either input is TOP ==> the result is TOP
2682 const Type *t = phase->type( in(MemNode::Memory) );
2683 if( t == Type::TOP ) return Type::TOP;
2684 t = phase->type( in(MemNode::Address) );
2685 if( t == Type::TOP ) return Type::TOP;
2686 t = phase->type( in(MemNode::ValueIn) );
2687 if( t == Type::TOP ) return Type::TOP;
2688 // If extra input is TOP ==> the result is TOP
2689 t = phase->type( in(MemNode::OopStore) );
2690 if( t == Type::TOP ) return Type::TOP;
2691
2692 return StoreNode::Value( phase );
2693 }
2694
2695
2696 //=============================================================================
2697 //----------------------------------SCMemProjNode------------------------------
2698 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2699 {
2700 return bottom_type();
2701 }
2702
2703 //=============================================================================
2704 //----------------------------------LoadStoreNode------------------------------
2705 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2706 : Node(required),
2707 _type(rt),
2708 _adr_type(at)
2709 {
2710 init_req(MemNode::Control, c );
2711 init_req(MemNode::Memory , mem);
2712 init_req(MemNode::Address, adr);
2713 init_req(MemNode::ValueIn, val);
2714 init_class_id(Class_LoadStore);
2715 }
2716
2717 uint LoadStoreNode::ideal_reg() const {
2718 return _type->ideal_reg();
2719 }
2720
2721 bool LoadStoreNode::result_not_used() const {
2722 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2723 Node *x = fast_out(i);
2724 if (x->Opcode() == Op_SCMemProj) continue;
2725 return false;
2726 }
2727 return true;
2728 }
2729
2730 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2731
2732 //=============================================================================
2733 //----------------------------------LoadStoreConditionalNode--------------------
2734 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2735 init_req(ExpectedIn, ex );
2736 }
2737
2738 //=============================================================================
2739 //-------------------------------adr_type--------------------------------------
2740 // Do we Match on this edge index or not? Do not match memory
2741 const TypePtr* ClearArrayNode::adr_type() const {
2742 Node *adr = in(3);
2743 return MemNode::calculate_adr_type(adr->bottom_type());
2744 }
2745
2746 //------------------------------match_edge-------------------------------------
2747 // Do we Match on this edge index or not? Do not match memory
2748 uint ClearArrayNode::match_edge(uint idx) const {
2749 return idx > 1;
2750 }
2751
2752 //------------------------------Identity---------------------------------------
2753 // Clearing a zero length array does nothing
2754 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2755 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2756 }
2757
2758 //------------------------------Idealize---------------------------------------
2759 // Clearing a short array is faster with stores
2760 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2761 const int unit = BytesPerLong;
2762 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2763 if (!t) return NULL;
2764 if (!t->is_con()) return NULL;
2765 intptr_t raw_count = t->get_con();
2766 intptr_t size = raw_count;
2767 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2768 // Clearing nothing uses the Identity call.
2769 // Negative clears are possible on dead ClearArrays
2770 // (see jck test stmt114.stmt11402.val).
2771 if (size <= 0 || size % unit != 0) return NULL;
2772 intptr_t count = size / unit;
2773 // Length too long; use fast hardware clear
2774 if (size > Matcher::init_array_short_size) return NULL;
2775 Node *mem = in(1);
2776 if( phase->type(mem)==Type::TOP ) return NULL;
2777 Node *adr = in(3);
2778 const Type* at = phase->type(adr);
2779 if( at==Type::TOP ) return NULL;
2780 const TypePtr* atp = at->isa_ptr();
2781 // adjust atp to be the correct array element address type
2782 if (atp == NULL) atp = TypePtr::BOTTOM;
2783 else atp = atp->add_offset(Type::OffsetBot);
2784 // Get base for derived pointer purposes
2785 if( adr->Opcode() != Op_AddP ) Unimplemented();
2786 Node *base = adr->in(1);
2787
2788 Node *zero = phase->makecon(TypeLong::ZERO);
2789 Node *off = phase->MakeConX(BytesPerLong);
2790 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2791 count--;
2792 while( count-- ) {
2793 mem = phase->transform(mem);
2794 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2795 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2796 }
2797 return mem;
2798 }
2799
2800 //----------------------------step_through----------------------------------
2801 // Return allocation input memory edge if it is different instance
2802 // or itself if it is the one we are looking for.
2803 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2804 Node* n = *np;
2805 assert(n->is_ClearArray(), "sanity");
2806 intptr_t offset;
2807 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2808 // This method is called only before Allocate nodes are expanded during
2809 // macro nodes expansion. Before that ClearArray nodes are only generated
2810 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2811 assert(alloc != NULL, "should have allocation");
2812 if (alloc->_idx == instance_id) {
2813 // Can not bypass initialization of the instance we are looking for.
2814 return false;
2815 }
2816 // Otherwise skip it.
2817 InitializeNode* init = alloc->initialization();
2818 if (init != NULL)
2819 *np = init->in(TypeFunc::Memory);
2820 else
2821 *np = alloc->in(TypeFunc::Memory);
2822 return true;
2823 }
2824
2825 //----------------------------clear_memory-------------------------------------
2826 // Generate code to initialize object storage to zero.
2827 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2828 intptr_t start_offset,
2829 Node* end_offset,
2830 PhaseGVN* phase) {
2831 Compile* C = phase->C;
2832 intptr_t offset = start_offset;
2833
2834 int unit = BytesPerLong;
2835 if ((offset % unit) != 0) {
2836 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2837 adr = phase->transform(adr);
2838 const TypePtr* atp = TypeRawPtr::BOTTOM;
2839 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2840 mem = phase->transform(mem);
2841 offset += BytesPerInt;
2842 }
2843 assert((offset % unit) == 0, "");
2844
2845 // Initialize the remaining stuff, if any, with a ClearArray.
2846 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2847 }
2848
2849 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2850 Node* start_offset,
2851 Node* end_offset,
2852 PhaseGVN* phase) {
2853 if (start_offset == end_offset) {
2854 // nothing to do
2855 return mem;
2856 }
2857
2858 Compile* C = phase->C;
2859 int unit = BytesPerLong;
2860 Node* zbase = start_offset;
2861 Node* zend = end_offset;
2862
2863 // Scale to the unit required by the CPU:
2864 if (!Matcher::init_array_count_is_in_bytes) {
2865 Node* shift = phase->intcon(exact_log2(unit));
2866 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2867 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2868 }
2869
2870 // Bulk clear double-words
2871 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2872 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2873 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2874 return phase->transform(mem);
2875 }
2876
2877 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2878 intptr_t start_offset,
2879 intptr_t end_offset,
2880 PhaseGVN* phase) {
2881 if (start_offset == end_offset) {
2882 // nothing to do
2883 return mem;
2884 }
2885
2886 Compile* C = phase->C;
2887 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2888 intptr_t done_offset = end_offset;
2889 if ((done_offset % BytesPerLong) != 0) {
2890 done_offset -= BytesPerInt;
2891 }
2892 if (done_offset > start_offset) {
2893 mem = clear_memory(ctl, mem, dest,
2894 start_offset, phase->MakeConX(done_offset), phase);
2895 }
2896 if (done_offset < end_offset) { // emit the final 32-bit store
2897 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2898 adr = phase->transform(adr);
2899 const TypePtr* atp = TypeRawPtr::BOTTOM;
2900 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2901 mem = phase->transform(mem);
2902 done_offset += BytesPerInt;
2903 }
2904 assert(done_offset == end_offset, "");
2905 return mem;
2906 }
2907
2908 //=============================================================================
2909 // Do not match memory edge.
2910 uint StrIntrinsicNode::match_edge(uint idx) const {
2911 return idx == 2 || idx == 3;
2912 }
2913
2914 //------------------------------Ideal------------------------------------------
2915 // Return a node which is more "ideal" than the current node. Strip out
2916 // control copies
2917 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2918 if (remove_dead_region(phase, can_reshape)) return this;
2919 // Don't bother trying to transform a dead node
2920 if (in(0) && in(0)->is_top()) return NULL;
2921
2922 if (can_reshape) {
2923 Node* mem = phase->transform(in(MemNode::Memory));
2924 // If transformed to a MergeMem, get the desired slice
2925 uint alias_idx = phase->C->get_alias_index(adr_type());
2926 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2927 if (mem != in(MemNode::Memory)) {
2928 set_req(MemNode::Memory, mem);
2929 return this;
2930 }
2931 }
2932 return NULL;
2933 }
2934
2935 //------------------------------Value------------------------------------------
2936 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2937 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2938 return bottom_type();
2939 }
2940
2941 //=============================================================================
2942 //------------------------------match_edge-------------------------------------
2943 // Do not match memory edge
2944 uint EncodeISOArrayNode::match_edge(uint idx) const {
2945 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2946 }
2947
2948 //------------------------------Ideal------------------------------------------
2949 // Return a node which is more "ideal" than the current node. Strip out
2950 // control copies
2951 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2952 return remove_dead_region(phase, can_reshape) ? this : NULL;
2953 }
2954
2955 //------------------------------Value------------------------------------------
2956 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2957 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2958 return bottom_type();
2959 }
2960
2961 //=============================================================================
2962 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2963 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2964 _adr_type(C->get_adr_type(alias_idx))
2965 {
2966 init_class_id(Class_MemBar);
2967 Node* top = C->top();
2968 init_req(TypeFunc::I_O,top);
2969 init_req(TypeFunc::FramePtr,top);
2970 init_req(TypeFunc::ReturnAdr,top);
2971 if (precedent != NULL)
2972 init_req(TypeFunc::Parms, precedent);
2973 }
2974
2975 //------------------------------cmp--------------------------------------------
2976 uint MemBarNode::hash() const { return NO_HASH; }
2977 uint MemBarNode::cmp( const Node &n ) const {
2978 return (&n == this); // Always fail except on self
2979 }
2980
2981 //------------------------------make-------------------------------------------
2982 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2983 switch (opcode) {
2984 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
2985 case Op_LoadFence: return new(C) LoadFenceNode(C, atp, pn);
2986 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
2987 case Op_StoreFence: return new(C) StoreFenceNode(C, atp, pn);
2988 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
2989 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
2990 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
2991 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
2992 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
2993 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
2994 default: ShouldNotReachHere(); return NULL;
2995 }
2996 }
2997
2998 //------------------------------Ideal------------------------------------------
2999 // Return a node which is more "ideal" than the current node. Strip out
3000 // control copies
3001 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3002 if (remove_dead_region(phase, can_reshape)) return this;
3003 // Don't bother trying to transform a dead node
3004 if (in(0) && in(0)->is_top()) {
3005 return NULL;
3006 }
3007
3008 // Eliminate volatile MemBars for scalar replaced objects.
3009 if (can_reshape && req() == (Precedent+1)) {
3010 bool eliminate = false;
3011 int opc = Opcode();
3012 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3013 // Volatile field loads and stores.
3014 Node* my_mem = in(MemBarNode::Precedent);
3015 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3016 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3017 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3018 // replace this Precedent (decodeN) with the Load instead.
3019 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3020 Node* load_node = my_mem->in(1);
3021 set_req(MemBarNode::Precedent, load_node);
3022 phase->is_IterGVN()->_worklist.push(my_mem);
3023 my_mem = load_node;
3024 } else {
3025 assert(my_mem->unique_out() == this, "sanity");
3026 del_req(Precedent);
3027 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3028 my_mem = NULL;
3029 }
3030 }
3031 if (my_mem != NULL && my_mem->is_Mem()) {
3032 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3033 // Check for scalar replaced object reference.
3034 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3035 t_oop->offset() != Type::OffsetBot &&
3036 t_oop->offset() != Type::OffsetTop) {
3037 eliminate = true;
3038 }
3039 }
3040 } else if (opc == Op_MemBarRelease) {
3041 // Final field stores.
3042 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3043 if ((alloc != NULL) && alloc->is_Allocate() &&
3044 alloc->as_Allocate()->_is_non_escaping) {
3045 // The allocated object does not escape.
3046 eliminate = true;
3047 }
3048 }
3049 if (eliminate) {
3050 // Replace MemBar projections by its inputs.
3051 PhaseIterGVN* igvn = phase->is_IterGVN();
3052 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3053 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3054 // Must return either the original node (now dead) or a new node
3055 // (Do not return a top here, since that would break the uniqueness of top.)
3056 return new (phase->C) ConINode(TypeInt::ZERO);
3057 }
3058 }
3059 return NULL;
3060 }
3061
3062 //------------------------------Value------------------------------------------
3063 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3064 if( !in(0) ) return Type::TOP;
3065 if( phase->type(in(0)) == Type::TOP )
3066 return Type::TOP;
3067 return TypeTuple::MEMBAR;
3068 }
3069
3070 //------------------------------match------------------------------------------
3071 // Construct projections for memory.
3072 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3073 switch (proj->_con) {
3074 case TypeFunc::Control:
3075 case TypeFunc::Memory:
3076 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3077 }
3078 ShouldNotReachHere();
3079 return NULL;
3080 }
3081
3082 //===========================InitializeNode====================================
3083 // SUMMARY:
3084 // This node acts as a memory barrier on raw memory, after some raw stores.
3085 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3086 // The Initialize can 'capture' suitably constrained stores as raw inits.
3087 // It can coalesce related raw stores into larger units (called 'tiles').
3088 // It can avoid zeroing new storage for memory units which have raw inits.
3089 // At macro-expansion, it is marked 'complete', and does not optimize further.
3090 //
3091 // EXAMPLE:
3092 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3093 // ctl = incoming control; mem* = incoming memory
3094 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3095 // First allocate uninitialized memory and fill in the header:
3096 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3097 // ctl := alloc.Control; mem* := alloc.Memory*
3098 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3099 // Then initialize to zero the non-header parts of the raw memory block:
3100 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3101 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3102 // After the initialize node executes, the object is ready for service:
3103 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3104 // Suppose its body is immediately initialized as {1,2}:
3105 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3106 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3107 // mem.SLICE(#short[*]) := store2
3108 //
3109 // DETAILS:
3110 // An InitializeNode collects and isolates object initialization after
3111 // an AllocateNode and before the next possible safepoint. As a
3112 // memory barrier (MemBarNode), it keeps critical stores from drifting
3113 // down past any safepoint or any publication of the allocation.
3114 // Before this barrier, a newly-allocated object may have uninitialized bits.
3115 // After this barrier, it may be treated as a real oop, and GC is allowed.
3116 //
3117 // The semantics of the InitializeNode include an implicit zeroing of
3118 // the new object from object header to the end of the object.
3119 // (The object header and end are determined by the AllocateNode.)
3120 //
3121 // Certain stores may be added as direct inputs to the InitializeNode.
3122 // These stores must update raw memory, and they must be to addresses
3123 // derived from the raw address produced by AllocateNode, and with
3124 // a constant offset. They must be ordered by increasing offset.
3125 // The first one is at in(RawStores), the last at in(req()-1).
3126 // Unlike most memory operations, they are not linked in a chain,
3127 // but are displayed in parallel as users of the rawmem output of
3128 // the allocation.
3129 //
3130 // (See comments in InitializeNode::capture_store, which continue
3131 // the example given above.)
3132 //
3133 // When the associated Allocate is macro-expanded, the InitializeNode
3134 // may be rewritten to optimize collected stores. A ClearArrayNode
3135 // may also be created at that point to represent any required zeroing.
3136 // The InitializeNode is then marked 'complete', prohibiting further
3137 // capturing of nearby memory operations.
3138 //
3139 // During macro-expansion, all captured initializations which store
3140 // constant values of 32 bits or smaller are coalesced (if advantageous)
3141 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3142 // initialized in fewer memory operations. Memory words which are
3143 // covered by neither tiles nor non-constant stores are pre-zeroed
3144 // by explicit stores of zero. (The code shape happens to do all
3145 // zeroing first, then all other stores, with both sequences occurring
3146 // in order of ascending offsets.)
3147 //
3148 // Alternatively, code may be inserted between an AllocateNode and its
3149 // InitializeNode, to perform arbitrary initialization of the new object.
3150 // E.g., the object copying intrinsics insert complex data transfers here.
3151 // The initialization must then be marked as 'complete' disable the
3152 // built-in zeroing semantics and the collection of initializing stores.
3153 //
3154 // While an InitializeNode is incomplete, reads from the memory state
3155 // produced by it are optimizable if they match the control edge and
3156 // new oop address associated with the allocation/initialization.
3157 // They return a stored value (if the offset matches) or else zero.
3158 // A write to the memory state, if it matches control and address,
3159 // and if it is to a constant offset, may be 'captured' by the
3160 // InitializeNode. It is cloned as a raw memory operation and rewired
3161 // inside the initialization, to the raw oop produced by the allocation.
3162 // Operations on addresses which are provably distinct (e.g., to
3163 // other AllocateNodes) are allowed to bypass the initialization.
3164 //
3165 // The effect of all this is to consolidate object initialization
3166 // (both arrays and non-arrays, both piecewise and bulk) into a
3167 // single location, where it can be optimized as a unit.
3168 //
3169 // Only stores with an offset less than TrackedInitializationLimit words
3170 // will be considered for capture by an InitializeNode. This puts a
3171 // reasonable limit on the complexity of optimized initializations.
3172
3173 //---------------------------InitializeNode------------------------------------
3174 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3175 : _is_complete(Incomplete), _does_not_escape(false),
3176 MemBarNode(C, adr_type, rawoop)
3177 {
3178 init_class_id(Class_Initialize);
3179
3180 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3181 assert(in(RawAddress) == rawoop, "proper init");
3182 // Note: allocation() can be NULL, for secondary initialization barriers
3183 }
3184
3185 // Since this node is not matched, it will be processed by the
3186 // register allocator. Declare that there are no constraints
3187 // on the allocation of the RawAddress edge.
3188 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3189 // This edge should be set to top, by the set_complete. But be conservative.
3190 if (idx == InitializeNode::RawAddress)
3191 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3192 return RegMask::Empty;
3193 }
3194
3195 Node* InitializeNode::memory(uint alias_idx) {
3196 Node* mem = in(Memory);
3197 if (mem->is_MergeMem()) {
3198 return mem->as_MergeMem()->memory_at(alias_idx);
3199 } else {
3200 // incoming raw memory is not split
3201 return mem;
3202 }
3203 }
3204
3205 bool InitializeNode::is_non_zero() {
3206 if (is_complete()) return false;
3207 remove_extra_zeroes();
3208 return (req() > RawStores);
3209 }
3210
3211 void InitializeNode::set_complete(PhaseGVN* phase) {
3212 assert(!is_complete(), "caller responsibility");
3213 _is_complete = Complete;
3214
3215 // After this node is complete, it contains a bunch of
3216 // raw-memory initializations. There is no need for
3217 // it to have anything to do with non-raw memory effects.
3218 // Therefore, tell all non-raw users to re-optimize themselves,
3219 // after skipping the memory effects of this initialization.
3220 PhaseIterGVN* igvn = phase->is_IterGVN();
3221 if (igvn) igvn->add_users_to_worklist(this);
3222 }
3223
3224 // convenience function
3225 // return false if the init contains any stores already
3226 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3227 InitializeNode* init = initialization();
3228 if (init == NULL || init->is_complete()) return false;
3229 init->remove_extra_zeroes();
3230 // for now, if this allocation has already collected any inits, bail:
3231 if (init->is_non_zero()) return false;
3232 init->set_complete(phase);
3233 return true;
3234 }
3235
3236 void InitializeNode::remove_extra_zeroes() {
3237 if (req() == RawStores) return;
3238 Node* zmem = zero_memory();
3239 uint fill = RawStores;
3240 for (uint i = fill; i < req(); i++) {
3241 Node* n = in(i);
3242 if (n->is_top() || n == zmem) continue; // skip
3243 if (fill < i) set_req(fill, n); // compact
3244 ++fill;
3245 }
3246 // delete any empty spaces created:
3247 while (fill < req()) {
3248 del_req(fill);
3249 }
3250 }
3251
3252 // Helper for remembering which stores go with which offsets.
3253 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3254 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3255 intptr_t offset = -1;
3256 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3257 phase, offset);
3258 if (base == NULL) return -1; // something is dead,
3259 if (offset < 0) return -1; // dead, dead
3260 return offset;
3261 }
3262
3263 // Helper for proving that an initialization expression is
3264 // "simple enough" to be folded into an object initialization.
3265 // Attempts to prove that a store's initial value 'n' can be captured
3266 // within the initialization without creating a vicious cycle, such as:
3267 // { Foo p = new Foo(); p.next = p; }
3268 // True for constants and parameters and small combinations thereof.
3269 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3270 if (n == NULL) return true; // (can this really happen?)
3271 if (n->is_Proj()) n = n->in(0);
3272 if (n == this) return false; // found a cycle
3273 if (n->is_Con()) return true;
3274 if (n->is_Start()) return true; // params, etc., are OK
3275 if (n->is_Root()) return true; // even better
3276
3277 Node* ctl = n->in(0);
3278 if (ctl != NULL && !ctl->is_top()) {
3279 if (ctl->is_Proj()) ctl = ctl->in(0);
3280 if (ctl == this) return false;
3281
3282 // If we already know that the enclosing memory op is pinned right after
3283 // the init, then any control flow that the store has picked up
3284 // must have preceded the init, or else be equal to the init.
3285 // Even after loop optimizations (which might change control edges)
3286 // a store is never pinned *before* the availability of its inputs.
3287 if (!MemNode::all_controls_dominate(n, this))
3288 return false; // failed to prove a good control
3289 }
3290
3291 // Check data edges for possible dependencies on 'this'.
3292 if ((count += 1) > 20) return false; // complexity limit
3293 for (uint i = 1; i < n->req(); i++) {
3294 Node* m = n->in(i);
3295 if (m == NULL || m == n || m->is_top()) continue;
3296 uint first_i = n->find_edge(m);
3297 if (i != first_i) continue; // process duplicate edge just once
3298 if (!detect_init_independence(m, count)) {
3299 return false;
3300 }
3301 }
3302
3303 return true;
3304 }
3305
3306 // Here are all the checks a Store must pass before it can be moved into
3307 // an initialization. Returns zero if a check fails.
3308 // On success, returns the (constant) offset to which the store applies,
3309 // within the initialized memory.
3310 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3311 const int FAIL = 0;
3312 if (st->req() != MemNode::ValueIn + 1)
3313 return FAIL; // an inscrutable StoreNode (card mark?)
3314 Node* ctl = st->in(MemNode::Control);
3315 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3316 return FAIL; // must be unconditional after the initialization
3317 Node* mem = st->in(MemNode::Memory);
3318 if (!(mem->is_Proj() && mem->in(0) == this))
3319 return FAIL; // must not be preceded by other stores
3320 Node* adr = st->in(MemNode::Address);
3321 intptr_t offset;
3322 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3323 if (alloc == NULL)
3324 return FAIL; // inscrutable address
3325 if (alloc != allocation())
3326 return FAIL; // wrong allocation! (store needs to float up)
3327 Node* val = st->in(MemNode::ValueIn);
3328 int complexity_count = 0;
3329 if (!detect_init_independence(val, complexity_count))
3330 return FAIL; // stored value must be 'simple enough'
3331
3332 // The Store can be captured only if nothing after the allocation
3333 // and before the Store is using the memory location that the store
3334 // overwrites.
3335 bool failed = false;
3336 // If is_complete_with_arraycopy() is true the shape of the graph is
3337 // well defined and is safe so no need for extra checks.
3338 if (!is_complete_with_arraycopy()) {
3339 // We are going to look at each use of the memory state following
3340 // the allocation to make sure nothing reads the memory that the
3341 // Store writes.
3342 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3343 int alias_idx = phase->C->get_alias_index(t_adr);
3344 ResourceMark rm;
3345 Unique_Node_List mems;
3346 mems.push(mem);
3347 Node* unique_merge = NULL;
3348 for (uint next = 0; next < mems.size(); ++next) {
3349 Node *m = mems.at(next);
3350 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3351 Node *n = m->fast_out(j);
3352 if (n->outcnt() == 0) {
3353 continue;
3354 }
3355 if (n == st) {
3356 continue;
3357 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3358 // If the control of this use is different from the control
3359 // of the Store which is right after the InitializeNode then
3360 // this node cannot be between the InitializeNode and the
3361 // Store.
3362 continue;
3363 } else if (n->is_MergeMem()) {
3364 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3365 // We can hit a MergeMemNode (that will likely go away
3366 // later) that is a direct use of the memory state
3367 // following the InitializeNode on the same slice as the
3368 // store node that we'd like to capture. We need to check
3369 // the uses of the MergeMemNode.
3370 mems.push(n);
3371 }
3372 } else if (n->is_Mem()) {
3373 Node* other_adr = n->in(MemNode::Address);
3374 if (other_adr == adr) {
3375 failed = true;
3376 break;
3377 } else {
3378 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3379 if (other_t_adr != NULL) {
3380 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3381 if (other_alias_idx == alias_idx) {
3382 // A load from the same memory slice as the store right
3383 // after the InitializeNode. We check the control of the
3384 // object/array that is loaded from. If it's the same as
3385 // the store control then we cannot capture the store.
3386 assert(!n->is_Store(), "2 stores to same slice on same control?");
3387 Node* base = other_adr;
3388 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3389 base = base->in(AddPNode::Base);
3390 if (base != NULL) {
3391 base = base->uncast();
3392 if (base->is_Proj() && base->in(0) == alloc) {
3393 failed = true;
3394 break;
3395 }
3396 }
3397 }
3398 }
3399 }
3400 } else {
3401 failed = true;
3402 break;
3403 }
3404 }
3405 }
3406 }
3407 if (failed) {
3408 if (!can_reshape) {
3409 // We decided we couldn't capture the store during parsing. We
3410 // should try again during the next IGVN once the graph is
3411 // cleaner.
3412 phase->C->record_for_igvn(st);
3413 }
3414 return FAIL;
3415 }
3416
3417 return offset; // success
3418 }
3419
3420 // Find the captured store in(i) which corresponds to the range
3421 // [start..start+size) in the initialized object.
3422 // If there is one, return its index i. If there isn't, return the
3423 // negative of the index where it should be inserted.
3424 // Return 0 if the queried range overlaps an initialization boundary
3425 // or if dead code is encountered.
3426 // If size_in_bytes is zero, do not bother with overlap checks.
3427 int InitializeNode::captured_store_insertion_point(intptr_t start,
3428 int size_in_bytes,
3429 PhaseTransform* phase) {
3430 const int FAIL = 0, MAX_STORE = BytesPerLong;
3431
3432 if (is_complete())
3433 return FAIL; // arraycopy got here first; punt
3434
3435 assert(allocation() != NULL, "must be present");
3436
3437 // no negatives, no header fields:
3438 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3439
3440 // after a certain size, we bail out on tracking all the stores:
3441 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3442 if (start >= ti_limit) return FAIL;
3443
3444 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3445 if (i >= limit) return -(int)i; // not found; here is where to put it
3446
3447 Node* st = in(i);
3448 intptr_t st_off = get_store_offset(st, phase);
3449 if (st_off < 0) {
3450 if (st != zero_memory()) {
3451 return FAIL; // bail out if there is dead garbage
3452 }
3453 } else if (st_off > start) {
3454 // ...we are done, since stores are ordered
3455 if (st_off < start + size_in_bytes) {
3456 return FAIL; // the next store overlaps
3457 }
3458 return -(int)i; // not found; here is where to put it
3459 } else if (st_off < start) {
3460 if (size_in_bytes != 0 &&
3461 start < st_off + MAX_STORE &&
3462 start < st_off + st->as_Store()->memory_size()) {
3463 return FAIL; // the previous store overlaps
3464 }
3465 } else {
3466 if (size_in_bytes != 0 &&
3467 st->as_Store()->memory_size() != size_in_bytes) {
3468 return FAIL; // mismatched store size
3469 }
3470 return i;
3471 }
3472
3473 ++i;
3474 }
3475 }
3476
3477 // Look for a captured store which initializes at the offset 'start'
3478 // with the given size. If there is no such store, and no other
3479 // initialization interferes, then return zero_memory (the memory
3480 // projection of the AllocateNode).
3481 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3482 PhaseTransform* phase) {
3483 assert(stores_are_sane(phase), "");
3484 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3485 if (i == 0) {
3486 return NULL; // something is dead
3487 } else if (i < 0) {
3488 return zero_memory(); // just primordial zero bits here
3489 } else {
3490 Node* st = in(i); // here is the store at this position
3491 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3492 return st;
3493 }
3494 }
3495
3496 // Create, as a raw pointer, an address within my new object at 'offset'.
3497 Node* InitializeNode::make_raw_address(intptr_t offset,
3498 PhaseTransform* phase) {
3499 Node* addr = in(RawAddress);
3500 if (offset != 0) {
3501 Compile* C = phase->C;
3502 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3503 phase->MakeConX(offset)) );
3504 }
3505 return addr;
3506 }
3507
3508 // Clone the given store, converting it into a raw store
3509 // initializing a field or element of my new object.
3510 // Caller is responsible for retiring the original store,
3511 // with subsume_node or the like.
3512 //
3513 // From the example above InitializeNode::InitializeNode,
3514 // here are the old stores to be captured:
3515 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3516 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3517 //
3518 // Here is the changed code; note the extra edges on init:
3519 // alloc = (Allocate ...)
3520 // rawoop = alloc.RawAddress
3521 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3522 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3523 // init = (Initialize alloc.Control alloc.Memory rawoop
3524 // rawstore1 rawstore2)
3525 //
3526 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3527 PhaseTransform* phase, bool can_reshape) {
3528 assert(stores_are_sane(phase), "");
3529
3530 if (start < 0) return NULL;
3531 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3532
3533 Compile* C = phase->C;
3534 int size_in_bytes = st->memory_size();
3535 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3536 if (i == 0) return NULL; // bail out
3537 Node* prev_mem = NULL; // raw memory for the captured store
3538 if (i > 0) {
3539 prev_mem = in(i); // there is a pre-existing store under this one
3540 set_req(i, C->top()); // temporarily disconnect it
3541 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3542 } else {
3543 i = -i; // no pre-existing store
3544 prev_mem = zero_memory(); // a slice of the newly allocated object
3545 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3546 set_req(--i, C->top()); // reuse this edge; it has been folded away
3547 else
3548 ins_req(i, C->top()); // build a new edge
3549 }
3550 Node* new_st = st->clone();
3551 new_st->set_req(MemNode::Control, in(Control));
3552 new_st->set_req(MemNode::Memory, prev_mem);
3553 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3554 new_st = phase->transform(new_st);
3555
3556 // At this point, new_st might have swallowed a pre-existing store
3557 // at the same offset, or perhaps new_st might have disappeared,
3558 // if it redundantly stored the same value (or zero to fresh memory).
3559
3560 // In any case, wire it in:
3561 set_req(i, new_st);
3562
3563 // The caller may now kill the old guy.
3564 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3565 assert(check_st == new_st || check_st == NULL, "must be findable");
3566 assert(!is_complete(), "");
3567 return new_st;
3568 }
3569
3570 static bool store_constant(jlong* tiles, int num_tiles,
3571 intptr_t st_off, int st_size,
3572 jlong con) {
3573 if ((st_off & (st_size-1)) != 0)
3574 return false; // strange store offset (assume size==2**N)
3575 address addr = (address)tiles + st_off;
3576 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3577 switch (st_size) {
3578 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3579 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3580 case sizeof(jint): *(jint*) addr = (jint) con; break;
3581 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3582 default: return false; // strange store size (detect size!=2**N here)
3583 }
3584 return true; // return success to caller
3585 }
3586
3587 // Coalesce subword constants into int constants and possibly
3588 // into long constants. The goal, if the CPU permits,
3589 // is to initialize the object with a small number of 64-bit tiles.
3590 // Also, convert floating-point constants to bit patterns.
3591 // Non-constants are not relevant to this pass.
3592 //
3593 // In terms of the running example on InitializeNode::InitializeNode
3594 // and InitializeNode::capture_store, here is the transformation
3595 // of rawstore1 and rawstore2 into rawstore12:
3596 // alloc = (Allocate ...)
3597 // rawoop = alloc.RawAddress
3598 // tile12 = 0x00010002
3599 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3600 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3601 //
3602 void
3603 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3604 Node* size_in_bytes,
3605 PhaseGVN* phase) {
3606 Compile* C = phase->C;
3607
3608 assert(stores_are_sane(phase), "");
3609 // Note: After this pass, they are not completely sane,
3610 // since there may be some overlaps.
3611
3612 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3613
3614 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3615 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3616 size_limit = MIN2(size_limit, ti_limit);
3617 size_limit = align_size_up(size_limit, BytesPerLong);
3618 int num_tiles = size_limit / BytesPerLong;
3619
3620 // allocate space for the tile map:
3621 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3622 jlong tiles_buf[small_len];
3623 Node* nodes_buf[small_len];
3624 jlong inits_buf[small_len];
3625 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3626 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3627 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3628 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3629 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3630 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3631 // tiles: exact bitwise model of all primitive constants
3632 // nodes: last constant-storing node subsumed into the tiles model
3633 // inits: which bytes (in each tile) are touched by any initializations
3634
3635 //// Pass A: Fill in the tile model with any relevant stores.
3636
3637 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3638 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3639 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3640 Node* zmem = zero_memory(); // initially zero memory state
3641 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3642 Node* st = in(i);
3643 intptr_t st_off = get_store_offset(st, phase);
3644
3645 // Figure out the store's offset and constant value:
3646 if (st_off < header_size) continue; //skip (ignore header)
3647 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3648 int st_size = st->as_Store()->memory_size();
3649 if (st_off + st_size > size_limit) break;
3650
3651 // Record which bytes are touched, whether by constant or not.
3652 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3653 continue; // skip (strange store size)
3654
3655 const Type* val = phase->type(st->in(MemNode::ValueIn));
3656 if (!val->singleton()) continue; //skip (non-con store)
3657 BasicType type = val->basic_type();
3658
3659 jlong con = 0;
3660 switch (type) {
3661 case T_INT: con = val->is_int()->get_con(); break;
3662 case T_LONG: con = val->is_long()->get_con(); break;
3663 case T_FLOAT: con = jint_cast(val->getf()); break;
3664 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3665 default: continue; //skip (odd store type)
3666 }
3667
3668 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3669 st->Opcode() == Op_StoreL) {
3670 continue; // This StoreL is already optimal.
3671 }
3672
3673 // Store down the constant.
3674 store_constant(tiles, num_tiles, st_off, st_size, con);
3675
3676 intptr_t j = st_off >> LogBytesPerLong;
3677
3678 if (type == T_INT && st_size == BytesPerInt
3679 && (st_off & BytesPerInt) == BytesPerInt) {
3680 jlong lcon = tiles[j];
3681 if (!Matcher::isSimpleConstant64(lcon) &&
3682 st->Opcode() == Op_StoreI) {
3683 // This StoreI is already optimal by itself.
3684 jint* intcon = (jint*) &tiles[j];
3685 intcon[1] = 0; // undo the store_constant()
3686
3687 // If the previous store is also optimal by itself, back up and
3688 // undo the action of the previous loop iteration... if we can.
3689 // But if we can't, just let the previous half take care of itself.
3690 st = nodes[j];
3691 st_off -= BytesPerInt;
3692 con = intcon[0];
3693 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3694 assert(st_off >= header_size, "still ignoring header");
3695 assert(get_store_offset(st, phase) == st_off, "must be");
3696 assert(in(i-1) == zmem, "must be");
3697 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3698 assert(con == tcon->is_int()->get_con(), "must be");
3699 // Undo the effects of the previous loop trip, which swallowed st:
3700 intcon[0] = 0; // undo store_constant()
3701 set_req(i-1, st); // undo set_req(i, zmem)
3702 nodes[j] = NULL; // undo nodes[j] = st
3703 --old_subword; // undo ++old_subword
3704 }
3705 continue; // This StoreI is already optimal.
3706 }
3707 }
3708
3709 // This store is not needed.
3710 set_req(i, zmem);
3711 nodes[j] = st; // record for the moment
3712 if (st_size < BytesPerLong) // something has changed
3713 ++old_subword; // includes int/float, but who's counting...
3714 else ++old_long;
3715 }
3716
3717 if ((old_subword + old_long) == 0)
3718 return; // nothing more to do
3719
3720 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3721 // Be sure to insert them before overlapping non-constant stores.
3722 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3723 for (int j = 0; j < num_tiles; j++) {
3724 jlong con = tiles[j];
3725 jlong init = inits[j];
3726 if (con == 0) continue;
3727 jint con0, con1; // split the constant, address-wise
3728 jint init0, init1; // split the init map, address-wise
3729 { union { jlong con; jint intcon[2]; } u;
3730 u.con = con;
3731 con0 = u.intcon[0];
3732 con1 = u.intcon[1];
3733 u.con = init;
3734 init0 = u.intcon[0];
3735 init1 = u.intcon[1];
3736 }
3737
3738 Node* old = nodes[j];
3739 assert(old != NULL, "need the prior store");
3740 intptr_t offset = (j * BytesPerLong);
3741
3742 bool split = !Matcher::isSimpleConstant64(con);
3743
3744 if (offset < header_size) {
3745 assert(offset + BytesPerInt >= header_size, "second int counts");
3746 assert(*(jint*)&tiles[j] == 0, "junk in header");
3747 split = true; // only the second word counts
3748 // Example: int a[] = { 42 ... }
3749 } else if (con0 == 0 && init0 == -1) {
3750 split = true; // first word is covered by full inits
3751 // Example: int a[] = { ... foo(), 42 ... }
3752 } else if (con1 == 0 && init1 == -1) {
3753 split = true; // second word is covered by full inits
3754 // Example: int a[] = { ... 42, foo() ... }
3755 }
3756
3757 // Here's a case where init0 is neither 0 nor -1:
3758 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3759 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3760 // In this case the tile is not split; it is (jlong)42.
3761 // The big tile is stored down, and then the foo() value is inserted.
3762 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3763
3764 Node* ctl = old->in(MemNode::Control);
3765 Node* adr = make_raw_address(offset, phase);
3766 const TypePtr* atp = TypeRawPtr::BOTTOM;
3767
3768 // One or two coalesced stores to plop down.
3769 Node* st[2];
3770 intptr_t off[2];
3771 int nst = 0;
3772 if (!split) {
3773 ++new_long;
3774 off[nst] = offset;
3775 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3776 phase->longcon(con), T_LONG, MemNode::unordered);
3777 } else {
3778 // Omit either if it is a zero.
3779 if (con0 != 0) {
3780 ++new_int;
3781 off[nst] = offset;
3782 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3783 phase->intcon(con0), T_INT, MemNode::unordered);
3784 }
3785 if (con1 != 0) {
3786 ++new_int;
3787 offset += BytesPerInt;
3788 adr = make_raw_address(offset, phase);
3789 off[nst] = offset;
3790 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3791 phase->intcon(con1), T_INT, MemNode::unordered);
3792 }
3793 }
3794
3795 // Insert second store first, then the first before the second.
3796 // Insert each one just before any overlapping non-constant stores.
3797 while (nst > 0) {
3798 Node* st1 = st[--nst];
3799 C->copy_node_notes_to(st1, old);
3800 st1 = phase->transform(st1);
3801 offset = off[nst];
3802 assert(offset >= header_size, "do not smash header");
3803 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3804 guarantee(ins_idx != 0, "must re-insert constant store");
3805 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3806 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3807 set_req(--ins_idx, st1);
3808 else
3809 ins_req(ins_idx, st1);
3810 }
3811 }
3812
3813 if (PrintCompilation && WizardMode)
3814 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3815 old_subword, old_long, new_int, new_long);
3816 if (C->log() != NULL)
3817 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3818 old_subword, old_long, new_int, new_long);
3819
3820 // Clean up any remaining occurrences of zmem:
3821 remove_extra_zeroes();
3822 }
3823
3824 // Explore forward from in(start) to find the first fully initialized
3825 // word, and return its offset. Skip groups of subword stores which
3826 // together initialize full words. If in(start) is itself part of a
3827 // fully initialized word, return the offset of in(start). If there
3828 // are no following full-word stores, or if something is fishy, return
3829 // a negative value.
3830 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3831 int int_map = 0;
3832 intptr_t int_map_off = 0;
3833 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3834
3835 for (uint i = start, limit = req(); i < limit; i++) {
3836 Node* st = in(i);
3837
3838 intptr_t st_off = get_store_offset(st, phase);
3839 if (st_off < 0) break; // return conservative answer
3840
3841 int st_size = st->as_Store()->memory_size();
3842 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3843 return st_off; // we found a complete word init
3844 }
3845
3846 // update the map:
3847
3848 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3849 if (this_int_off != int_map_off) {
3850 // reset the map:
3851 int_map = 0;
3852 int_map_off = this_int_off;
3853 }
3854
3855 int subword_off = st_off - this_int_off;
3856 int_map |= right_n_bits(st_size) << subword_off;
3857 if ((int_map & FULL_MAP) == FULL_MAP) {
3858 return this_int_off; // we found a complete word init
3859 }
3860
3861 // Did this store hit or cross the word boundary?
3862 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3863 if (next_int_off == this_int_off + BytesPerInt) {
3864 // We passed the current int, without fully initializing it.
3865 int_map_off = next_int_off;
3866 int_map >>= BytesPerInt;
3867 } else if (next_int_off > this_int_off + BytesPerInt) {
3868 // We passed the current and next int.
3869 return this_int_off + BytesPerInt;
3870 }
3871 }
3872
3873 return -1;
3874 }
3875
3876
3877 // Called when the associated AllocateNode is expanded into CFG.
3878 // At this point, we may perform additional optimizations.
3879 // Linearize the stores by ascending offset, to make memory
3880 // activity as coherent as possible.
3881 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3882 intptr_t header_size,
3883 Node* size_in_bytes,
3884 PhaseGVN* phase) {
3885 assert(!is_complete(), "not already complete");
3886 assert(stores_are_sane(phase), "");
3887 assert(allocation() != NULL, "must be present");
3888
3889 remove_extra_zeroes();
3890
3891 if (ReduceFieldZeroing || ReduceBulkZeroing)
3892 // reduce instruction count for common initialization patterns
3893 coalesce_subword_stores(header_size, size_in_bytes, phase);
3894
3895 Node* zmem = zero_memory(); // initially zero memory state
3896 Node* inits = zmem; // accumulating a linearized chain of inits
3897 #ifdef ASSERT
3898 intptr_t first_offset = allocation()->minimum_header_size();
3899 intptr_t last_init_off = first_offset; // previous init offset
3900 intptr_t last_init_end = first_offset; // previous init offset+size
3901 intptr_t last_tile_end = first_offset; // previous tile offset+size
3902 #endif
3903 intptr_t zeroes_done = header_size;
3904
3905 bool do_zeroing = true; // we might give up if inits are very sparse
3906 int big_init_gaps = 0; // how many large gaps have we seen?
3907
3908 if (ZeroTLAB) do_zeroing = false;
3909 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3910
3911 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3912 Node* st = in(i);
3913 intptr_t st_off = get_store_offset(st, phase);
3914 if (st_off < 0)
3915 break; // unknown junk in the inits
3916 if (st->in(MemNode::Memory) != zmem)
3917 break; // complicated store chains somehow in list
3918
3919 int st_size = st->as_Store()->memory_size();
3920 intptr_t next_init_off = st_off + st_size;
3921
3922 if (do_zeroing && zeroes_done < next_init_off) {
3923 // See if this store needs a zero before it or under it.
3924 intptr_t zeroes_needed = st_off;
3925
3926 if (st_size < BytesPerInt) {
3927 // Look for subword stores which only partially initialize words.
3928 // If we find some, we must lay down some word-level zeroes first,
3929 // underneath the subword stores.
3930 //
3931 // Examples:
3932 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3933 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3934 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3935 //
3936 // Note: coalesce_subword_stores may have already done this,
3937 // if it was prompted by constant non-zero subword initializers.
3938 // But this case can still arise with non-constant stores.
3939
3940 intptr_t next_full_store = find_next_fullword_store(i, phase);
3941
3942 // In the examples above:
3943 // in(i) p q r s x y z
3944 // st_off 12 13 14 15 12 13 14
3945 // st_size 1 1 1 1 1 1 1
3946 // next_full_s. 12 16 16 16 16 16 16
3947 // z's_done 12 16 16 16 12 16 12
3948 // z's_needed 12 16 16 16 16 16 16
3949 // zsize 0 0 0 0 4 0 4
3950 if (next_full_store < 0) {
3951 // Conservative tack: Zero to end of current word.
3952 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3953 } else {
3954 // Zero to beginning of next fully initialized word.
3955 // Or, don't zero at all, if we are already in that word.
3956 assert(next_full_store >= zeroes_needed, "must go forward");
3957 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3958 zeroes_needed = next_full_store;
3959 }
3960 }
3961
3962 if (zeroes_needed > zeroes_done) {
3963 intptr_t zsize = zeroes_needed - zeroes_done;
3964 // Do some incremental zeroing on rawmem, in parallel with inits.
3965 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3966 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3967 zeroes_done, zeroes_needed,
3968 phase);
3969 zeroes_done = zeroes_needed;
3970 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3971 do_zeroing = false; // leave the hole, next time
3972 }
3973 }
3974
3975 // Collect the store and move on:
3976 st->set_req(MemNode::Memory, inits);
3977 inits = st; // put it on the linearized chain
3978 set_req(i, zmem); // unhook from previous position
3979
3980 if (zeroes_done == st_off)
3981 zeroes_done = next_init_off;
3982
3983 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3984
3985 #ifdef ASSERT
3986 // Various order invariants. Weaker than stores_are_sane because
3987 // a large constant tile can be filled in by smaller non-constant stores.
3988 assert(st_off >= last_init_off, "inits do not reverse");
3989 last_init_off = st_off;
3990 const Type* val = NULL;
3991 if (st_size >= BytesPerInt &&
3992 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3993 (int)val->basic_type() < (int)T_OBJECT) {
3994 assert(st_off >= last_tile_end, "tiles do not overlap");
3995 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3996 last_tile_end = MAX2(last_tile_end, next_init_off);
3997 } else {
3998 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3999 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4000 assert(st_off >= last_init_end, "inits do not overlap");
4001 last_init_end = next_init_off; // it's a non-tile
4002 }
4003 #endif //ASSERT
4004 }
4005
4006 remove_extra_zeroes(); // clear out all the zmems left over
4007 add_req(inits);
4008
4009 if (!ZeroTLAB) {
4010 // If anything remains to be zeroed, zero it all now.
4011 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4012 // if it is the last unused 4 bytes of an instance, forget about it
4013 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4014 if (zeroes_done + BytesPerLong >= size_limit) {
4015 assert(allocation() != NULL, "");
4016 if (allocation()->Opcode() == Op_Allocate) {
4017 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
4018 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4019 if (zeroes_done == k->layout_helper())
4020 zeroes_done = size_limit;
4021 }
4022 }
4023 if (zeroes_done < size_limit) {
4024 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4025 zeroes_done, size_in_bytes, phase);
4026 }
4027 }
4028
4029 set_complete(phase);
4030 return rawmem;
4031 }
4032
4033
4034 #ifdef ASSERT
4035 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4036 if (is_complete())
4037 return true; // stores could be anything at this point
4038 assert(allocation() != NULL, "must be present");
4039 intptr_t last_off = allocation()->minimum_header_size();
4040 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4041 Node* st = in(i);
4042 intptr_t st_off = get_store_offset(st, phase);
4043 if (st_off < 0) continue; // ignore dead garbage
4044 if (last_off > st_off) {
4045 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
4046 this->dump(2);
4047 assert(false, "ascending store offsets");
4048 return false;
4049 }
4050 last_off = st_off + st->as_Store()->memory_size();
4051 }
4052 return true;
4053 }
4054 #endif //ASSERT
4055
4056
4057
4058
4059 //============================MergeMemNode=====================================
4060 //
4061 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4062 // contributing store or call operations. Each contributor provides the memory
4063 // state for a particular "alias type" (see Compile::alias_type). For example,
4064 // if a MergeMem has an input X for alias category #6, then any memory reference
4065 // to alias category #6 may use X as its memory state input, as an exact equivalent
4066 // to using the MergeMem as a whole.
4067 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4068 //
4069 // (Here, the <N> notation gives the index of the relevant adr_type.)
4070 //
4071 // In one special case (and more cases in the future), alias categories overlap.
4072 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4073 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4074 // it is exactly equivalent to that state W:
4075 // MergeMem(<Bot>: W) <==> W
4076 //
4077 // Usually, the merge has more than one input. In that case, where inputs
4078 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4079 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4080 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4081 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4082 //
4083 // A merge can take a "wide" memory state as one of its narrow inputs.
4084 // This simply means that the merge observes out only the relevant parts of
4085 // the wide input. That is, wide memory states arriving at narrow merge inputs
4086 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4087 //
4088 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4089 // and that memory slices "leak through":
4090 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4091 //
4092 // But, in such a cascade, repeated memory slices can "block the leak":
4093 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4094 //
4095 // In the last example, Y is not part of the combined memory state of the
4096 // outermost MergeMem. The system must, of course, prevent unschedulable
4097 // memory states from arising, so you can be sure that the state Y is somehow
4098 // a precursor to state Y'.
4099 //
4100 //
4101 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4102 // of each MergeMemNode array are exactly the numerical alias indexes, including
4103 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4104 // Compile::alias_type (and kin) produce and manage these indexes.
4105 //
4106 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4107 // (Note that this provides quick access to the top node inside MergeMem methods,
4108 // without the need to reach out via TLS to Compile::current.)
4109 //
4110 // As a consequence of what was just described, a MergeMem that represents a full
4111 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4112 // containing all alias categories.
4113 //
4114 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4115 //
4116 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4117 // a memory state for the alias type <N>, or else the top node, meaning that
4118 // there is no particular input for that alias type. Note that the length of
4119 // a MergeMem is variable, and may be extended at any time to accommodate new
4120 // memory states at larger alias indexes. When merges grow, they are of course
4121 // filled with "top" in the unused in() positions.
4122 //
4123 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4124 // (Top was chosen because it works smoothly with passes like GCM.)
4125 //
4126 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4127 // the type of random VM bits like TLS references.) Since it is always the
4128 // first non-Bot memory slice, some low-level loops use it to initialize an
4129 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4130 //
4131 //
4132 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4133 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4134 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4135 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4136 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4137 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4138 //
4139 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4140 // really that different from the other memory inputs. An abbreviation called
4141 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4142 //
4143 //
4144 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4145 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4146 // that "emerges though" the base memory will be marked as excluding the alias types
4147 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4148 //
4149 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4150 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4151 //
4152 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4153 // (It is currently unimplemented.) As you can see, the resulting merge is
4154 // actually a disjoint union of memory states, rather than an overlay.
4155 //
4156
4157 //------------------------------MergeMemNode-----------------------------------
4158 Node* MergeMemNode::make_empty_memory() {
4159 Node* empty_memory = (Node*) Compile::current()->top();
4160 assert(empty_memory->is_top(), "correct sentinel identity");
4161 return empty_memory;
4162 }
4163
4164 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4165 init_class_id(Class_MergeMem);
4166 // all inputs are nullified in Node::Node(int)
4167 // set_input(0, NULL); // no control input
4168
4169 // Initialize the edges uniformly to top, for starters.
4170 Node* empty_mem = make_empty_memory();
4171 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4172 init_req(i,empty_mem);
4173 }
4174 assert(empty_memory() == empty_mem, "");
4175
4176 if( new_base != NULL && new_base->is_MergeMem() ) {
4177 MergeMemNode* mdef = new_base->as_MergeMem();
4178 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4179 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4180 mms.set_memory(mms.memory2());
4181 }
4182 assert(base_memory() == mdef->base_memory(), "");
4183 } else {
4184 set_base_memory(new_base);
4185 }
4186 }
4187
4188 // Make a new, untransformed MergeMem with the same base as 'mem'.
4189 // If mem is itself a MergeMem, populate the result with the same edges.
4190 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4191 return new(C) MergeMemNode(mem);
4192 }
4193
4194 //------------------------------cmp--------------------------------------------
4195 uint MergeMemNode::hash() const { return NO_HASH; }
4196 uint MergeMemNode::cmp( const Node &n ) const {
4197 return (&n == this); // Always fail except on self
4198 }
4199
4200 //------------------------------Identity---------------------------------------
4201 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4202 // Identity if this merge point does not record any interesting memory
4203 // disambiguations.
4204 Node* base_mem = base_memory();
4205 Node* empty_mem = empty_memory();
4206 if (base_mem != empty_mem) { // Memory path is not dead?
4207 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4208 Node* mem = in(i);
4209 if (mem != empty_mem && mem != base_mem) {
4210 return this; // Many memory splits; no change
4211 }
4212 }
4213 }
4214 return base_mem; // No memory splits; ID on the one true input
4215 }
4216
4217 //------------------------------Ideal------------------------------------------
4218 // This method is invoked recursively on chains of MergeMem nodes
4219 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4220 // Remove chain'd MergeMems
4221 //
4222 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4223 // relative to the "in(Bot)". Since we are patching both at the same time,
4224 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4225 // but rewrite each "in(i)" relative to the new "in(Bot)".
4226 Node *progress = NULL;
4227
4228
4229 Node* old_base = base_memory();
4230 Node* empty_mem = empty_memory();
4231 if (old_base == empty_mem)
4232 return NULL; // Dead memory path.
4233
4234 MergeMemNode* old_mbase;
4235 if (old_base != NULL && old_base->is_MergeMem())
4236 old_mbase = old_base->as_MergeMem();
4237 else
4238 old_mbase = NULL;
4239 Node* new_base = old_base;
4240
4241 // simplify stacked MergeMems in base memory
4242 if (old_mbase) new_base = old_mbase->base_memory();
4243
4244 // the base memory might contribute new slices beyond my req()
4245 if (old_mbase) grow_to_match(old_mbase);
4246
4247 // Look carefully at the base node if it is a phi.
4248 PhiNode* phi_base;
4249 if (new_base != NULL && new_base->is_Phi())
4250 phi_base = new_base->as_Phi();
4251 else
4252 phi_base = NULL;
4253
4254 Node* phi_reg = NULL;
4255 uint phi_len = (uint)-1;
4256 if (phi_base != NULL && !phi_base->is_copy()) {
4257 // do not examine phi if degraded to a copy
4258 phi_reg = phi_base->region();
4259 phi_len = phi_base->req();
4260 // see if the phi is unfinished
4261 for (uint i = 1; i < phi_len; i++) {
4262 if (phi_base->in(i) == NULL) {
4263 // incomplete phi; do not look at it yet!
4264 phi_reg = NULL;
4265 phi_len = (uint)-1;
4266 break;
4267 }
4268 }
4269 }
4270
4271 // Note: We do not call verify_sparse on entry, because inputs
4272 // can normalize to the base_memory via subsume_node or similar
4273 // mechanisms. This method repairs that damage.
4274
4275 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4276
4277 // Look at each slice.
4278 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4279 Node* old_in = in(i);
4280 // calculate the old memory value
4281 Node* old_mem = old_in;
4282 if (old_mem == empty_mem) old_mem = old_base;
4283 assert(old_mem == memory_at(i), "");
4284
4285 // maybe update (reslice) the old memory value
4286
4287 // simplify stacked MergeMems
4288 Node* new_mem = old_mem;
4289 MergeMemNode* old_mmem;
4290 if (old_mem != NULL && old_mem->is_MergeMem())
4291 old_mmem = old_mem->as_MergeMem();
4292 else
4293 old_mmem = NULL;
4294 if (old_mmem == this) {
4295 // This can happen if loops break up and safepoints disappear.
4296 // A merge of BotPtr (default) with a RawPtr memory derived from a
4297 // safepoint can be rewritten to a merge of the same BotPtr with
4298 // the BotPtr phi coming into the loop. If that phi disappears
4299 // also, we can end up with a self-loop of the mergemem.
4300 // In general, if loops degenerate and memory effects disappear,
4301 // a mergemem can be left looking at itself. This simply means
4302 // that the mergemem's default should be used, since there is
4303 // no longer any apparent effect on this slice.
4304 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4305 // from start. Update the input to TOP.
4306 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4307 }
4308 else if (old_mmem != NULL) {
4309 new_mem = old_mmem->memory_at(i);
4310 }
4311 // else preceding memory was not a MergeMem
4312
4313 // replace equivalent phis (unfortunately, they do not GVN together)
4314 if (new_mem != NULL && new_mem != new_base &&
4315 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4316 if (new_mem->is_Phi()) {
4317 PhiNode* phi_mem = new_mem->as_Phi();
4318 for (uint i = 1; i < phi_len; i++) {
4319 if (phi_base->in(i) != phi_mem->in(i)) {
4320 phi_mem = NULL;
4321 break;
4322 }
4323 }
4324 if (phi_mem != NULL) {
4325 // equivalent phi nodes; revert to the def
4326 new_mem = new_base;
4327 }
4328 }
4329 }
4330
4331 // maybe store down a new value
4332 Node* new_in = new_mem;
4333 if (new_in == new_base) new_in = empty_mem;
4334
4335 if (new_in != old_in) {
4336 // Warning: Do not combine this "if" with the previous "if"
4337 // A memory slice might have be be rewritten even if it is semantically
4338 // unchanged, if the base_memory value has changed.
4339 set_req(i, new_in);
4340 progress = this; // Report progress
4341 }
4342 }
4343
4344 if (new_base != old_base) {
4345 set_req(Compile::AliasIdxBot, new_base);
4346 // Don't use set_base_memory(new_base), because we need to update du.
4347 assert(base_memory() == new_base, "");
4348 progress = this;
4349 }
4350
4351 if( base_memory() == this ) {
4352 // a self cycle indicates this memory path is dead
4353 set_req(Compile::AliasIdxBot, empty_mem);
4354 }
4355
4356 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4357 // Recursion must occur after the self cycle check above
4358 if( base_memory()->is_MergeMem() ) {
4359 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4360 Node *m = phase->transform(new_mbase); // Rollup any cycles
4361 if( m != NULL && (m->is_top() ||
4362 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4363 // propagate rollup of dead cycle to self
4364 set_req(Compile::AliasIdxBot, empty_mem);
4365 }
4366 }
4367
4368 if( base_memory() == empty_mem ) {
4369 progress = this;
4370 // Cut inputs during Parse phase only.
4371 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4372 if( !can_reshape ) {
4373 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4374 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4375 }
4376 }
4377 }
4378
4379 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4380 // Check if PhiNode::Ideal's "Split phis through memory merges"
4381 // transform should be attempted. Look for this->phi->this cycle.
4382 uint merge_width = req();
4383 if (merge_width > Compile::AliasIdxRaw) {
4384 PhiNode* phi = base_memory()->as_Phi();
4385 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4386 if (phi->in(i) == this) {
4387 phase->is_IterGVN()->_worklist.push(phi);
4388 break;
4389 }
4390 }
4391 }
4392 }
4393
4394 assert(progress || verify_sparse(), "please, no dups of base");
4395 return progress;
4396 }
4397
4398 //-------------------------set_base_memory-------------------------------------
4399 void MergeMemNode::set_base_memory(Node *new_base) {
4400 Node* empty_mem = empty_memory();
4401 set_req(Compile::AliasIdxBot, new_base);
4402 assert(memory_at(req()) == new_base, "must set default memory");
4403 // Clear out other occurrences of new_base:
4404 if (new_base != empty_mem) {
4405 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4406 if (in(i) == new_base) set_req(i, empty_mem);
4407 }
4408 }
4409 }
4410
4411 //------------------------------out_RegMask------------------------------------
4412 const RegMask &MergeMemNode::out_RegMask() const {
4413 return RegMask::Empty;
4414 }
4415
4416 //------------------------------dump_spec--------------------------------------
4417 #ifndef PRODUCT
4418 void MergeMemNode::dump_spec(outputStream *st) const {
4419 st->print(" {");
4420 Node* base_mem = base_memory();
4421 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4422 Node* mem = memory_at(i);
4423 if (mem == base_mem) { st->print(" -"); continue; }
4424 st->print( " N%d:", mem->_idx );
4425 Compile::current()->get_adr_type(i)->dump_on(st);
4426 }
4427 st->print(" }");
4428 }
4429 #endif // !PRODUCT
4430
4431
4432 #ifdef ASSERT
4433 static bool might_be_same(Node* a, Node* b) {
4434 if (a == b) return true;
4435 if (!(a->is_Phi() || b->is_Phi())) return false;
4436 // phis shift around during optimization
4437 return true; // pretty stupid...
4438 }
4439
4440 // verify a narrow slice (either incoming or outgoing)
4441 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4442 if (!VerifyAliases) return; // don't bother to verify unless requested
4443 if (is_error_reported()) return; // muzzle asserts when debugging an error
4444 if (Node::in_dump()) return; // muzzle asserts when printing
4445 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4446 assert(n != NULL, "");
4447 // Elide intervening MergeMem's
4448 while (n->is_MergeMem()) {
4449 n = n->as_MergeMem()->memory_at(alias_idx);
4450 }
4451 Compile* C = Compile::current();
4452 const TypePtr* n_adr_type = n->adr_type();
4453 if (n == m->empty_memory()) {
4454 // Implicit copy of base_memory()
4455 } else if (n_adr_type != TypePtr::BOTTOM) {
4456 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4457 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4458 } else {
4459 // A few places like make_runtime_call "know" that VM calls are narrow,
4460 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4461 bool expected_wide_mem = false;
4462 if (n == m->base_memory()) {
4463 expected_wide_mem = true;
4464 } else if (alias_idx == Compile::AliasIdxRaw ||
4465 n == m->memory_at(Compile::AliasIdxRaw)) {
4466 expected_wide_mem = true;
4467 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4468 // memory can "leak through" calls on channels that
4469 // are write-once. Allow this also.
4470 expected_wide_mem = true;
4471 }
4472 assert(expected_wide_mem, "expected narrow slice replacement");
4473 }
4474 }
4475 #else // !ASSERT
4476 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4477 #endif
4478
4479
4480 //-----------------------------memory_at---------------------------------------
4481 Node* MergeMemNode::memory_at(uint alias_idx) const {
4482 assert(alias_idx >= Compile::AliasIdxRaw ||
4483 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4484 "must avoid base_memory and AliasIdxTop");
4485
4486 // Otherwise, it is a narrow slice.
4487 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4488 Compile *C = Compile::current();
4489 if (is_empty_memory(n)) {
4490 // the array is sparse; empty slots are the "top" node
4491 n = base_memory();
4492 assert(Node::in_dump()
4493 || n == NULL || n->bottom_type() == Type::TOP
4494 || n->adr_type() == NULL // address is TOP
4495 || n->adr_type() == TypePtr::BOTTOM
4496 || n->adr_type() == TypeRawPtr::BOTTOM
4497 || Compile::current()->AliasLevel() == 0,
4498 "must be a wide memory");
4499 // AliasLevel == 0 if we are organizing the memory states manually.
4500 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4501 } else {
4502 // make sure the stored slice is sane
4503 #ifdef ASSERT
4504 if (is_error_reported() || Node::in_dump()) {
4505 } else if (might_be_same(n, base_memory())) {
4506 // Give it a pass: It is a mostly harmless repetition of the base.
4507 // This can arise normally from node subsumption during optimization.
4508 } else {
4509 verify_memory_slice(this, alias_idx, n);
4510 }
4511 #endif
4512 }
4513 return n;
4514 }
4515
4516 //---------------------------set_memory_at-------------------------------------
4517 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4518 verify_memory_slice(this, alias_idx, n);
4519 Node* empty_mem = empty_memory();
4520 if (n == base_memory()) n = empty_mem; // collapse default
4521 uint need_req = alias_idx+1;
4522 if (req() < need_req) {
4523 if (n == empty_mem) return; // already the default, so do not grow me
4524 // grow the sparse array
4525 do {
4526 add_req(empty_mem);
4527 } while (req() < need_req);
4528 }
4529 set_req( alias_idx, n );
4530 }
4531
4532
4533
4534 //--------------------------iteration_setup------------------------------------
4535 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4536 if (other != NULL) {
4537 grow_to_match(other);
4538 // invariant: the finite support of mm2 is within mm->req()
4539 #ifdef ASSERT
4540 for (uint i = req(); i < other->req(); i++) {
4541 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4542 }
4543 #endif
4544 }
4545 // Replace spurious copies of base_memory by top.
4546 Node* base_mem = base_memory();
4547 if (base_mem != NULL && !base_mem->is_top()) {
4548 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4549 if (in(i) == base_mem)
4550 set_req(i, empty_memory());
4551 }
4552 }
4553 }
4554
4555 //---------------------------grow_to_match-------------------------------------
4556 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4557 Node* empty_mem = empty_memory();
4558 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4559 // look for the finite support of the other memory
4560 for (uint i = other->req(); --i >= req(); ) {
4561 if (other->in(i) != empty_mem) {
4562 uint new_len = i+1;
4563 while (req() < new_len) add_req(empty_mem);
4564 break;
4565 }
4566 }
4567 }
4568
4569 //---------------------------verify_sparse-------------------------------------
4570 #ifndef PRODUCT
4571 bool MergeMemNode::verify_sparse() const {
4572 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4573 Node* base_mem = base_memory();
4574 // The following can happen in degenerate cases, since empty==top.
4575 if (is_empty_memory(base_mem)) return true;
4576 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4577 assert(in(i) != NULL, "sane slice");
4578 if (in(i) == base_mem) return false; // should have been the sentinel value!
4579 }
4580 return true;
4581 }
4582
4583 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4584 Node* n;
4585 n = mm->in(idx);
4586 if (mem == n) return true; // might be empty_memory()
4587 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4588 if (mem == n) return true;
4589 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4590 if (mem == n) return true;
4591 if (n == NULL) break;
4592 }
4593 return false;
4594 }
4595 #endif // !PRODUCT