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