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.
22 *
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/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
41
42 // Portions of code courtesy of Clifford Click
43
44 // Optimization - Graph Style
45
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
47
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
50
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
57
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
68
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
73
74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
75 st->print(" @");
76 if (adr_type == NULL) {
77 st->print("NULL");
78 } else {
79 adr_type->dump_on(st);
80 Compile* C = Compile::current();
81 Compile::AliasType* atp = NULL;
82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
83 if (atp == NULL)
84 st->print(", idx=?\?;");
85 else if (atp->index() == Compile::AliasIdxBot)
86 st->print(", idx=Bot;");
87 else if (atp->index() == Compile::AliasIdxTop)
88 st->print(", idx=Top;");
89 else if (atp->index() == Compile::AliasIdxRaw)
90 st->print(", idx=Raw;");
91 else {
92 ciField* field = atp->field();
93 if (field) {
94 st->print(", name=");
95 field->print_name_on(st);
96 }
97 st->print(", idx=%d;", atp->index());
98 }
99 }
100 }
101
102 extern void print_alias_types();
103
104 #endif
105
106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
107 assert((t_oop != NULL), "sanity");
108 bool is_instance = t_oop->is_known_instance_field();
109 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
110 (load != NULL) && load->is_Load() &&
111 (phase->is_IterGVN() != NULL);
112 if (!(is_instance || is_boxed_value_load))
113 return mchain; // don't try to optimize non-instance types
114 uint instance_id = t_oop->instance_id();
115 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
116 Node *prev = NULL;
117 Node *result = mchain;
118 while (prev != result) {
119 prev = result;
120 if (result == start_mem)
121 break; // hit one of our sentinels
122 // skip over a call which does not affect this memory slice
123 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
124 Node *proj_in = result->in(0);
125 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
126 break; // hit one of our sentinels
127 } else if (proj_in->is_Call()) {
128 CallNode *call = proj_in->as_Call();
129 if (!call->may_modify(t_oop, phase)) { // returns false for instances
130 result = call->in(TypeFunc::Memory);
131 }
132 } else if (proj_in->is_Initialize()) {
133 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
134 // Stop if this is the initialization for the object instance which
135 // which contains this memory slice, otherwise skip over it.
136 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
137 break;
138 }
139 if (is_instance) {
140 result = proj_in->in(TypeFunc::Memory);
141 } else if (is_boxed_value_load) {
142 Node* klass = alloc->in(AllocateNode::KlassNode);
143 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
144 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
145 result = proj_in->in(TypeFunc::Memory); // not related allocation
146 }
147 }
148 } else if (proj_in->is_MemBar()) {
149 result = proj_in->in(TypeFunc::Memory);
150 } else {
151 assert(false, "unexpected projection");
152 }
153 } else if (result->is_ClearArray()) {
154 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
155 // Can not bypass initialization of the instance
156 // we are looking for.
157 break;
158 }
159 // Otherwise skip it (the call updated 'result' value).
160 } else if (result->is_MergeMem()) {
161 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
162 }
163 }
164 return result;
165 }
166
167 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
168 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
169 if (t_oop == NULL)
170 return mchain; // don't try to optimize non-oop types
171 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
172 bool is_instance = t_oop->is_known_instance_field();
173 PhaseIterGVN *igvn = phase->is_IterGVN();
174 if (is_instance && igvn != NULL && result->is_Phi()) {
175 PhiNode *mphi = result->as_Phi();
176 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
177 const TypePtr *t = mphi->adr_type();
178 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
179 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
180 t->is_oopptr()->cast_to_exactness(true)
181 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
182 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
183 // clone the Phi with our address type
184 result = mphi->split_out_instance(t_adr, igvn);
185 } else {
186 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
187 }
188 }
189 return result;
190 }
191
192 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
193 uint alias_idx = phase->C->get_alias_index(tp);
194 Node *mem = mmem;
195 #ifdef ASSERT
196 {
197 // Check that current type is consistent with the alias index used during graph construction
198 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
199 bool consistent = adr_check == NULL || adr_check->empty() ||
200 phase->C->must_alias(adr_check, alias_idx );
201 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
202 if( !consistent && adr_check != NULL && !adr_check->empty() &&
203 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
204 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
205 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
206 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
207 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
208 // don't assert if it is dead code.
209 consistent = true;
210 }
211 if( !consistent ) {
212 st->print("alias_idx==%d, adr_check==", alias_idx);
213 if( adr_check == NULL ) {
214 st->print("NULL");
215 } else {
216 adr_check->dump();
217 }
218 st->cr();
219 print_alias_types();
220 assert(consistent, "adr_check must match alias idx");
221 }
222 }
223 #endif
224 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
225 // means an array I have not precisely typed yet. Do not do any
226 // alias stuff with it any time soon.
227 const TypeOopPtr *toop = tp->isa_oopptr();
228 if( tp->base() != Type::AnyPtr &&
229 !(toop &&
230 toop->klass() != NULL &&
231 toop->klass()->is_java_lang_Object() &&
232 toop->offset() == Type::OffsetBot) ) {
233 // compress paths and change unreachable cycles to TOP
234 // If not, we can update the input infinitely along a MergeMem cycle
235 // Equivalent code in PhiNode::Ideal
236 Node* m = phase->transform(mmem);
237 // If transformed to a MergeMem, get the desired slice
238 // Otherwise the returned node represents memory for every slice
239 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
240 // Update input if it is progress over what we have now
241 }
242 return mem;
243 }
244
245 //--------------------------Ideal_common---------------------------------------
246 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
247 // Unhook non-raw memories from complete (macro-expanded) initializations.
248 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
249 // If our control input is a dead region, kill all below the region
250 Node *ctl = in(MemNode::Control);
251 if (ctl && remove_dead_region(phase, can_reshape))
252 return this;
253 ctl = in(MemNode::Control);
254 // Don't bother trying to transform a dead node
255 if (ctl && ctl->is_top()) return NodeSentinel;
256
257 PhaseIterGVN *igvn = phase->is_IterGVN();
258 // Wait if control on the worklist.
259 if (ctl && can_reshape && igvn != NULL) {
260 Node* bol = NULL;
261 Node* cmp = NULL;
262 if (ctl->in(0)->is_If()) {
263 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
264 bol = ctl->in(0)->in(1);
265 if (bol->is_Bool())
266 cmp = ctl->in(0)->in(1)->in(1);
267 }
268 if (igvn->_worklist.member(ctl) ||
269 (bol != NULL && igvn->_worklist.member(bol)) ||
270 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
271 // This control path may be dead.
272 // Delay this memory node transformation until the control is processed.
273 phase->is_IterGVN()->_worklist.push(this);
274 return NodeSentinel; // caller will return NULL
275 }
276 }
277 // Ignore if memory is dead, or self-loop
278 Node *mem = in(MemNode::Memory);
279 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
280 assert(mem != this, "dead loop in MemNode::Ideal");
281
282 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
283 // This memory slice may be dead.
284 // Delay this mem node transformation until the memory is processed.
285 phase->is_IterGVN()->_worklist.push(this);
286 return NodeSentinel; // caller will return NULL
287 }
288
289 Node *address = in(MemNode::Address);
290 const Type *t_adr = phase->type(address);
291 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
292
293 if (can_reshape && igvn != NULL &&
294 (igvn->_worklist.member(address) ||
295 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
296 // The address's base and type may change when the address is processed.
297 // Delay this mem node transformation until the address is processed.
298 phase->is_IterGVN()->_worklist.push(this);
299 return NodeSentinel; // caller will return NULL
300 }
301
302 // Do NOT remove or optimize the next lines: ensure a new alias index
303 // is allocated for an oop pointer type before Escape Analysis.
304 // Note: C++ will not remove it since the call has side effect.
305 if (t_adr->isa_oopptr()) {
306 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
307 }
308
309 #ifdef ASSERT
310 Node* base = NULL;
311 if (address->is_AddP())
312 base = address->in(AddPNode::Base);
313 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
314 !t_adr->isa_rawptr()) {
315 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
316 Compile* C = phase->C;
317 tty->cr();
318 tty->print_cr("===== NULL+offs not RAW address =====");
319 if (C->is_dead_node(this->_idx)) tty->print_cr("'this' is dead");
320 if ((ctl != NULL) && C->is_dead_node(ctl->_idx)) tty->print_cr("'ctl' is dead");
321 if (C->is_dead_node(mem->_idx)) tty->print_cr("'mem' is dead");
322 if (C->is_dead_node(address->_idx)) tty->print_cr("'address' is dead");
323 if (C->is_dead_node(base->_idx)) tty->print_cr("'base' is dead");
324 tty->cr();
325 base->dump(1);
326 tty->cr();
327 this->dump(2);
328 tty->print("this->adr_type(): "); adr_type()->dump(); tty->cr();
329 tty->print("phase->type(address): "); t_adr->dump(); tty->cr();
330 tty->print("phase->type(base): "); phase->type(address)->dump(); tty->cr();
331 tty->cr();
332 }
333 assert(base == NULL || t_adr->isa_rawptr() ||
334 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
335 #endif
336
337 // Avoid independent memory operations
338 Node* old_mem = mem;
339
340 // The code which unhooks non-raw memories from complete (macro-expanded)
341 // initializations was removed. After macro-expansion all stores catched
342 // by Initialize node became raw stores and there is no information
343 // which memory slices they modify. So it is unsafe to move any memory
344 // operation above these stores. Also in most cases hooked non-raw memories
345 // were already unhooked by using information from detect_ptr_independence()
346 // and find_previous_store().
347
348 if (mem->is_MergeMem()) {
349 MergeMemNode* mmem = mem->as_MergeMem();
350 const TypePtr *tp = t_adr->is_ptr();
351
352 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
353 }
354
355 if (mem != old_mem) {
356 set_req(MemNode::Memory, mem);
357 if (can_reshape && old_mem->outcnt() == 0) {
358 igvn->_worklist.push(old_mem);
359 }
360 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
361 return this;
362 }
363
364 // let the subclass continue analyzing...
365 return NULL;
366 }
367
368 // Helper function for proving some simple control dominations.
369 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
370 // Already assumes that 'dom' is available at 'sub', and that 'sub'
371 // is not a constant (dominated by the method's StartNode).
372 // Used by MemNode::find_previous_store to prove that the
373 // control input of a memory operation predates (dominates)
374 // an allocation it wants to look past.
375 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
376 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
377 return false; // Conservative answer for dead code
378
379 // Check 'dom'. Skip Proj and CatchProj nodes.
380 dom = dom->find_exact_control(dom);
381 if (dom == NULL || dom->is_top())
382 return false; // Conservative answer for dead code
383
384 if (dom == sub) {
385 // For the case when, for example, 'sub' is Initialize and the original
386 // 'dom' is Proj node of the 'sub'.
387 return false;
388 }
389
390 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
391 return true;
392
393 // 'dom' dominates 'sub' if its control edge and control edges
394 // of all its inputs dominate or equal to sub's control edge.
395
396 // Currently 'sub' is either Allocate, Initialize or Start nodes.
397 // Or Region for the check in LoadNode::Ideal();
398 // 'sub' should have sub->in(0) != NULL.
399 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
400 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
401
402 // Get control edge of 'sub'.
403 Node* orig_sub = sub;
404 sub = sub->find_exact_control(sub->in(0));
405 if (sub == NULL || sub->is_top())
406 return false; // Conservative answer for dead code
407
408 assert(sub->is_CFG(), "expecting control");
409
410 if (sub == dom)
411 return true;
412
413 if (sub->is_Start() || sub->is_Root())
414 return false;
415
416 {
417 // Check all control edges of 'dom'.
418
419 ResourceMark rm;
420 Arena* arena = Thread::current()->resource_area();
421 Node_List nlist(arena);
422 Unique_Node_List dom_list(arena);
423
424 dom_list.push(dom);
425 bool only_dominating_controls = false;
426
427 for (uint next = 0; next < dom_list.size(); next++) {
428 Node* n = dom_list.at(next);
429 if (n == orig_sub)
430 return false; // One of dom's inputs dominated by sub.
431 if (!n->is_CFG() && n->pinned()) {
432 // Check only own control edge for pinned non-control nodes.
433 n = n->find_exact_control(n->in(0));
434 if (n == NULL || n->is_top())
435 return false; // Conservative answer for dead code
436 assert(n->is_CFG(), "expecting control");
437 dom_list.push(n);
438 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
439 only_dominating_controls = true;
440 } else if (n->is_CFG()) {
441 if (n->dominates(sub, nlist))
442 only_dominating_controls = true;
443 else
444 return false;
445 } else {
446 // First, own control edge.
447 Node* m = n->find_exact_control(n->in(0));
448 if (m != NULL) {
449 if (m->is_top())
450 return false; // Conservative answer for dead code
451 dom_list.push(m);
452 }
453 // Now, the rest of edges.
454 uint cnt = n->req();
455 for (uint i = 1; i < cnt; i++) {
456 m = n->find_exact_control(n->in(i));
457 if (m == NULL || m->is_top())
458 continue;
459 dom_list.push(m);
460 }
461 }
462 }
463 return only_dominating_controls;
464 }
465 }
466
467 //---------------------detect_ptr_independence---------------------------------
468 // Used by MemNode::find_previous_store to prove that two base
469 // pointers are never equal.
470 // The pointers are accompanied by their associated allocations,
471 // if any, which have been previously discovered by the caller.
472 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
473 Node* p2, AllocateNode* a2,
474 PhaseTransform* phase) {
475 // Attempt to prove that these two pointers cannot be aliased.
476 // They may both manifestly be allocations, and they should differ.
477 // Or, if they are not both allocations, they can be distinct constants.
478 // Otherwise, one is an allocation and the other a pre-existing value.
479 if (a1 == NULL && a2 == NULL) { // neither an allocation
480 return (p1 != p2) && p1->is_Con() && p2->is_Con();
481 } else if (a1 != NULL && a2 != NULL) { // both allocations
482 return (a1 != a2);
483 } else if (a1 != NULL) { // one allocation a1
484 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
485 return all_controls_dominate(p2, a1);
486 } else { //(a2 != NULL) // one allocation a2
487 return all_controls_dominate(p1, a2);
488 }
489 return false;
490 }
491
492
493 // The logic for reordering loads and stores uses four steps:
494 // (a) Walk carefully past stores and initializations which we
495 // can prove are independent of this load.
496 // (b) Observe that the next memory state makes an exact match
497 // with self (load or store), and locate the relevant store.
498 // (c) Ensure that, if we were to wire self directly to the store,
499 // the optimizer would fold it up somehow.
500 // (d) Do the rewiring, and return, depending on some other part of
501 // the optimizer to fold up the load.
502 // This routine handles steps (a) and (b). Steps (c) and (d) are
503 // specific to loads and stores, so they are handled by the callers.
504 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
505 //
506 Node* MemNode::find_previous_store(PhaseTransform* phase) {
507 Node* ctrl = in(MemNode::Control);
508 Node* adr = in(MemNode::Address);
509 intptr_t offset = 0;
510 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
511 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
512
513 if (offset == Type::OffsetBot)
514 return NULL; // cannot unalias unless there are precise offsets
515
516 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
517
518 intptr_t size_in_bytes = memory_size();
519
520 Node* mem = in(MemNode::Memory); // start searching here...
521
522 int cnt = 50; // Cycle limiter
523 for (;;) { // While we can dance past unrelated stores...
524 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
525
526 if (mem->is_Store()) {
527 Node* st_adr = mem->in(MemNode::Address);
528 intptr_t st_offset = 0;
529 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
530 if (st_base == NULL)
531 break; // inscrutable pointer
532 if (st_offset != offset && st_offset != Type::OffsetBot) {
533 const int MAX_STORE = BytesPerLong;
534 if (st_offset >= offset + size_in_bytes ||
535 st_offset <= offset - MAX_STORE ||
536 st_offset <= offset - mem->as_Store()->memory_size()) {
537 // Success: The offsets are provably independent.
538 // (You may ask, why not just test st_offset != offset and be done?
539 // The answer is that stores of different sizes can co-exist
540 // in the same sequence of RawMem effects. We sometimes initialize
541 // a whole 'tile' of array elements with a single jint or jlong.)
542 mem = mem->in(MemNode::Memory);
543 continue; // (a) advance through independent store memory
544 }
545 }
546 if (st_base != base &&
547 detect_ptr_independence(base, alloc,
548 st_base,
549 AllocateNode::Ideal_allocation(st_base, phase),
550 phase)) {
551 // Success: The bases are provably independent.
552 mem = mem->in(MemNode::Memory);
553 continue; // (a) advance through independent store memory
554 }
555
556 // (b) At this point, if the bases or offsets do not agree, we lose,
557 // since we have not managed to prove 'this' and 'mem' independent.
558 if (st_base == base && st_offset == offset) {
559 return mem; // let caller handle steps (c), (d)
560 }
561
562 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
563 InitializeNode* st_init = mem->in(0)->as_Initialize();
564 AllocateNode* st_alloc = st_init->allocation();
565 if (st_alloc == NULL)
566 break; // something degenerated
567 bool known_identical = false;
568 bool known_independent = false;
569 if (alloc == st_alloc)
570 known_identical = true;
571 else if (alloc != NULL)
572 known_independent = true;
573 else if (all_controls_dominate(this, st_alloc))
574 known_independent = true;
575
576 if (known_independent) {
577 // The bases are provably independent: Either they are
578 // manifestly distinct allocations, or else the control
579 // of this load dominates the store's allocation.
580 int alias_idx = phase->C->get_alias_index(adr_type());
581 if (alias_idx == Compile::AliasIdxRaw) {
582 mem = st_alloc->in(TypeFunc::Memory);
583 } else {
584 mem = st_init->memory(alias_idx);
585 }
586 continue; // (a) advance through independent store memory
587 }
588
589 // (b) at this point, if we are not looking at a store initializing
590 // the same allocation we are loading from, we lose.
591 if (known_identical) {
592 // From caller, can_see_stored_value will consult find_captured_store.
593 return mem; // let caller handle steps (c), (d)
594 }
595
596 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
597 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
598 if (mem->is_Proj() && mem->in(0)->is_Call()) {
599 CallNode *call = mem->in(0)->as_Call();
600 if (!call->may_modify(addr_t, phase)) {
601 mem = call->in(TypeFunc::Memory);
602 continue; // (a) advance through independent call memory
603 }
604 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
605 mem = mem->in(0)->in(TypeFunc::Memory);
606 continue; // (a) advance through independent MemBar memory
607 } else if (mem->is_ClearArray()) {
608 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
609 // (the call updated 'mem' value)
610 continue; // (a) advance through independent allocation memory
611 } else {
612 // Can not bypass initialization of the instance
613 // we are looking for.
614 return mem;
615 }
616 } else if (mem->is_MergeMem()) {
617 int alias_idx = phase->C->get_alias_index(adr_type());
618 mem = mem->as_MergeMem()->memory_at(alias_idx);
619 continue; // (a) advance through independent MergeMem memory
620 }
621 }
622
623 // Unless there is an explicit 'continue', we must bail out here,
624 // because 'mem' is an inscrutable memory state (e.g., a call).
625 break;
626 }
627
628 return NULL; // bail out
629 }
630
631 //----------------------calculate_adr_type-------------------------------------
632 // Helper function. Notices when the given type of address hits top or bottom.
633 // Also, asserts a cross-check of the type against the expected address type.
634 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
635 if (t == Type::TOP) return NULL; // does not touch memory any more?
636 #ifdef PRODUCT
637 cross_check = NULL;
638 #else
639 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
640 #endif
641 const TypePtr* tp = t->isa_ptr();
642 if (tp == NULL) {
643 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
644 return TypePtr::BOTTOM; // touches lots of memory
645 } else {
646 #ifdef ASSERT
647 // %%%% [phh] We don't check the alias index if cross_check is
648 // TypeRawPtr::BOTTOM. Needs to be investigated.
649 if (cross_check != NULL &&
650 cross_check != TypePtr::BOTTOM &&
651 cross_check != TypeRawPtr::BOTTOM) {
652 // Recheck the alias index, to see if it has changed (due to a bug).
653 Compile* C = Compile::current();
654 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
655 "must stay in the original alias category");
656 // The type of the address must be contained in the adr_type,
657 // disregarding "null"-ness.
658 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
659 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
660 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
661 "real address must not escape from expected memory type");
662 }
663 #endif
664 return tp;
665 }
666 }
667
668 //------------------------adr_phi_is_loop_invariant----------------------------
669 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
670 // loop is loop invariant. Make a quick traversal of Phi and associated
671 // CastPP nodes, looking to see if they are a closed group within the loop.
672 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
673 // The idea is that the phi-nest must boil down to only CastPP nodes
674 // with the same data. This implies that any path into the loop already
675 // includes such a CastPP, and so the original cast, whatever its input,
676 // must be covered by an equivalent cast, with an earlier control input.
677 ResourceMark rm;
678
679 // The loop entry input of the phi should be the unique dominating
680 // node for every Phi/CastPP in the loop.
681 Unique_Node_List closure;
682 closure.push(adr_phi->in(LoopNode::EntryControl));
683
684 // Add the phi node and the cast to the worklist.
685 Unique_Node_List worklist;
686 worklist.push(adr_phi);
687 if( cast != NULL ){
688 if( !cast->is_ConstraintCast() ) return false;
689 worklist.push(cast);
690 }
691
692 // Begin recursive walk of phi nodes.
693 while( worklist.size() ){
694 // Take a node off the worklist
695 Node *n = worklist.pop();
696 if( !closure.member(n) ){
697 // Add it to the closure.
698 closure.push(n);
699 // Make a sanity check to ensure we don't waste too much time here.
700 if( closure.size() > 20) return false;
701 // This node is OK if:
702 // - it is a cast of an identical value
703 // - or it is a phi node (then we add its inputs to the worklist)
704 // Otherwise, the node is not OK, and we presume the cast is not invariant
705 if( n->is_ConstraintCast() ){
706 worklist.push(n->in(1));
707 } else if( n->is_Phi() ) {
708 for( uint i = 1; i < n->req(); i++ ) {
709 worklist.push(n->in(i));
710 }
711 } else {
712 return false;
713 }
714 }
715 }
716
717 // Quit when the worklist is empty, and we've found no offending nodes.
718 return true;
719 }
720
721 //------------------------------Ideal_DU_postCCP-------------------------------
722 // Find any cast-away of null-ness and keep its control. Null cast-aways are
723 // going away in this pass and we need to make this memory op depend on the
724 // gating null check.
725 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
726 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
727 }
728
729 // I tried to leave the CastPP's in. This makes the graph more accurate in
730 // some sense; we get to keep around the knowledge that an oop is not-null
731 // after some test. Alas, the CastPP's interfere with GVN (some values are
732 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
733 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
734 // some of the more trivial cases in the optimizer. Removing more useless
735 // Phi's started allowing Loads to illegally float above null checks. I gave
736 // up on this approach. CNC 10/20/2000
737 // This static method may be called not from MemNode (EncodePNode calls it).
738 // Only the control edge of the node 'n' might be updated.
739 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
740 Node *skipped_cast = NULL;
741 // Need a null check? Regular static accesses do not because they are
742 // from constant addresses. Array ops are gated by the range check (which
743 // always includes a NULL check). Just check field ops.
744 if( n->in(MemNode::Control) == NULL ) {
745 // Scan upwards for the highest location we can place this memory op.
746 while( true ) {
747 switch( adr->Opcode() ) {
748
749 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
750 adr = adr->in(AddPNode::Base);
751 continue;
752
753 case Op_DecodeN: // No change to NULL-ness, so peek thru
754 case Op_DecodeNKlass:
755 adr = adr->in(1);
756 continue;
757
758 case Op_EncodeP:
759 case Op_EncodePKlass:
760 // EncodeP node's control edge could be set by this method
761 // when EncodeP node depends on CastPP node.
762 //
763 // Use its control edge for memory op because EncodeP may go away
764 // later when it is folded with following or preceding DecodeN node.
765 if (adr->in(0) == NULL) {
766 // Keep looking for cast nodes.
767 adr = adr->in(1);
768 continue;
769 }
770 ccp->hash_delete(n);
771 n->set_req(MemNode::Control, adr->in(0));
772 ccp->hash_insert(n);
773 return n;
774
775 case Op_CastPP:
776 // If the CastPP is useless, just peek on through it.
777 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
778 // Remember the cast that we've peeked though. If we peek
779 // through more than one, then we end up remembering the highest
780 // one, that is, if in a loop, the one closest to the top.
781 skipped_cast = adr;
782 adr = adr->in(1);
783 continue;
784 }
785 // CastPP is going away in this pass! We need this memory op to be
786 // control-dependent on the test that is guarding the CastPP.
787 ccp->hash_delete(n);
788 n->set_req(MemNode::Control, adr->in(0));
789 ccp->hash_insert(n);
790 return n;
791
792 case Op_Phi:
793 // Attempt to float above a Phi to some dominating point.
794 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
795 // If we've already peeked through a Cast (which could have set the
796 // control), we can't float above a Phi, because the skipped Cast
797 // may not be loop invariant.
798 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
799 adr = adr->in(1);
800 continue;
801 }
802 }
803
804 // Intentional fallthrough!
805
806 // No obvious dominating point. The mem op is pinned below the Phi
807 // by the Phi itself. If the Phi goes away (no true value is merged)
808 // then the mem op can float, but not indefinitely. It must be pinned
809 // behind the controls leading to the Phi.
810 case Op_CheckCastPP:
811 // These usually stick around to change address type, however a
812 // useless one can be elided and we still need to pick up a control edge
813 if (adr->in(0) == NULL) {
814 // This CheckCastPP node has NO control and is likely useless. But we
815 // need check further up the ancestor chain for a control input to keep
816 // the node in place. 4959717.
817 skipped_cast = adr;
818 adr = adr->in(1);
819 continue;
820 }
821 ccp->hash_delete(n);
822 n->set_req(MemNode::Control, adr->in(0));
823 ccp->hash_insert(n);
824 return n;
825
826 // List of "safe" opcodes; those that implicitly block the memory
827 // op below any null check.
828 case Op_CastX2P: // no null checks on native pointers
829 case Op_Parm: // 'this' pointer is not null
830 case Op_LoadP: // Loading from within a klass
831 case Op_LoadN: // Loading from within a klass
832 case Op_LoadKlass: // Loading from within a klass
833 case Op_LoadNKlass: // Loading from within a klass
834 case Op_ConP: // Loading from a klass
835 case Op_ConN: // Loading from a klass
836 case Op_ConNKlass: // Loading from a klass
837 case Op_CreateEx: // Sucking up the guts of an exception oop
838 case Op_Con: // Reading from TLS
839 case Op_CMoveP: // CMoveP is pinned
840 case Op_CMoveN: // CMoveN is pinned
841 break; // No progress
842
843 case Op_Proj: // Direct call to an allocation routine
844 case Op_SCMemProj: // Memory state from store conditional ops
845 #ifdef ASSERT
846 {
847 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
848 const Node* call = adr->in(0);
849 if (call->is_CallJava()) {
850 const CallJavaNode* call_java = call->as_CallJava();
851 const TypeTuple *r = call_java->tf()->range();
852 assert(r->cnt() > TypeFunc::Parms, "must return value");
853 const Type* ret_type = r->field_at(TypeFunc::Parms);
854 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
855 // We further presume that this is one of
856 // new_instance_Java, new_array_Java, or
857 // the like, but do not assert for this.
858 } else if (call->is_Allocate()) {
859 // similar case to new_instance_Java, etc.
860 } else if (!call->is_CallLeaf()) {
861 // Projections from fetch_oop (OSR) are allowed as well.
862 ShouldNotReachHere();
863 }
864 }
865 #endif
866 break;
867 default:
868 ShouldNotReachHere();
869 }
870 break;
871 }
872 }
873
874 return NULL; // No progress
875 }
876
877
878 //=============================================================================
879 uint LoadNode::size_of() const { return sizeof(*this); }
880 uint LoadNode::cmp( const Node &n ) const
881 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
882 const Type *LoadNode::bottom_type() const { return _type; }
883 uint LoadNode::ideal_reg() const {
884 return _type->ideal_reg();
885 }
886
887 #ifndef PRODUCT
888 void LoadNode::dump_spec(outputStream *st) const {
889 MemNode::dump_spec(st);
890 if( !Verbose && !WizardMode ) {
891 // standard dump does this in Verbose and WizardMode
892 st->print(" #"); _type->dump_on(st);
893 }
894 }
895 #endif
896
897 #ifdef ASSERT
898 //----------------------------is_immutable_value-------------------------------
899 // Helper function to allow a raw load without control edge for some cases
900 bool LoadNode::is_immutable_value(Node* adr) {
901 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
902 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
903 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
904 in_bytes(JavaThread::osthread_offset())));
905 }
906 #endif
907
908 //----------------------------LoadNode::make-----------------------------------
909 // Polymorphic factory method:
910 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo) {
911 Compile* C = gvn.C;
912
913 // sanity check the alias category against the created node type
914 assert(!(adr_type->isa_oopptr() &&
915 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
916 "use LoadKlassNode instead");
917 assert(!(adr_type->isa_aryptr() &&
918 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
919 "use LoadRangeNode instead");
920 // Check control edge of raw loads
921 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
922 // oop will be recorded in oop map if load crosses safepoint
923 rt->isa_oopptr() || is_immutable_value(adr),
924 "raw memory operations should have control edge");
925 switch (bt) {
926 case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
927 case T_BYTE: return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
928 case T_INT: return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo);
929 case T_CHAR: return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo);
930 case T_SHORT: return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo);
931 case T_LONG: return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo);
932 case T_FLOAT: return new (C) LoadFNode (ctl, mem, adr, adr_type, rt, mo);
933 case T_DOUBLE: return new (C) LoadDNode (ctl, mem, adr, adr_type, rt, mo);
934 case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo);
935 case T_OBJECT:
936 #ifdef _LP64
937 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
938 Node* load = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo));
939 return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
940 } else
941 #endif
942 {
943 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
944 return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo);
945 }
946 }
947 ShouldNotReachHere();
948 return (LoadNode*)NULL;
949 }
950
951 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
952 bool require_atomic = true;
953 return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, require_atomic);
954 }
955
956
957
958
959 //------------------------------hash-------------------------------------------
960 uint LoadNode::hash() const {
961 // unroll addition of interesting fields
962 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
963 }
964
965 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
966 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
967 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
968 bool is_stable_ary = FoldStableValues &&
969 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
970 tp->isa_aryptr()->is_stable();
971
972 return (eliminate_boxing && non_volatile) || is_stable_ary;
973 }
974
975 return false;
976 }
977
978 //---------------------------can_see_stored_value------------------------------
979 // This routine exists to make sure this set of tests is done the same
980 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
981 // will change the graph shape in a way which makes memory alive twice at the
982 // same time (uses the Oracle model of aliasing), then some
983 // LoadXNode::Identity will fold things back to the equivalence-class model
984 // of aliasing.
985 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
986 Node* ld_adr = in(MemNode::Address);
987 intptr_t ld_off = 0;
988 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
989 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
990 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
991 // This is more general than load from boxing objects.
992 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
993 uint alias_idx = atp->index();
994 bool final = !atp->is_rewritable();
995 Node* result = NULL;
996 Node* current = st;
997 // Skip through chains of MemBarNodes checking the MergeMems for
998 // new states for the slice of this load. Stop once any other
999 // kind of node is encountered. Loads from final memory can skip
1000 // through any kind of MemBar but normal loads shouldn't skip
1001 // through MemBarAcquire since the could allow them to move out of
1002 // a synchronized region.
1003 while (current->is_Proj()) {
1004 int opc = current->in(0)->Opcode();
1005 if ((final && (opc == Op_MemBarAcquire ||
1006 opc == Op_MemBarAcquireLock ||
1007 opc == Op_LoadFence)) ||
1008 opc == Op_MemBarRelease ||
1009 opc == Op_StoreFence ||
1010 opc == Op_MemBarReleaseLock ||
1011 opc == Op_MemBarCPUOrder) {
1012 Node* mem = current->in(0)->in(TypeFunc::Memory);
1013 if (mem->is_MergeMem()) {
1014 MergeMemNode* merge = mem->as_MergeMem();
1015 Node* new_st = merge->memory_at(alias_idx);
1016 if (new_st == merge->base_memory()) {
1017 // Keep searching
1018 current = new_st;
1019 continue;
1020 }
1021 // Save the new memory state for the slice and fall through
1022 // to exit.
1023 result = new_st;
1024 }
1025 }
1026 break;
1027 }
1028 if (result != NULL) {
1029 st = result;
1030 }
1031 }
1032
1033 // Loop around twice in the case Load -> Initialize -> Store.
1034 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1035 for (int trip = 0; trip <= 1; trip++) {
1036
1037 if (st->is_Store()) {
1038 Node* st_adr = st->in(MemNode::Address);
1039 if (!phase->eqv(st_adr, ld_adr)) {
1040 // Try harder before giving up... Match raw and non-raw pointers.
1041 intptr_t st_off = 0;
1042 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1043 if (alloc == NULL) return NULL;
1044 if (alloc != ld_alloc) return NULL;
1045 if (ld_off != st_off) return NULL;
1046 // At this point we have proven something like this setup:
1047 // A = Allocate(...)
1048 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1049 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1050 // (Actually, we haven't yet proven the Q's are the same.)
1051 // In other words, we are loading from a casted version of
1052 // the same pointer-and-offset that we stored to.
1053 // Thus, we are able to replace L by V.
1054 }
1055 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1056 if (store_Opcode() != st->Opcode())
1057 return NULL;
1058 return st->in(MemNode::ValueIn);
1059 }
1060
1061 // A load from a freshly-created object always returns zero.
1062 // (This can happen after LoadNode::Ideal resets the load's memory input
1063 // to find_captured_store, which returned InitializeNode::zero_memory.)
1064 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1065 (st->in(0) == ld_alloc) &&
1066 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1067 // return a zero value for the load's basic type
1068 // (This is one of the few places where a generic PhaseTransform
1069 // can create new nodes. Think of it as lazily manifesting
1070 // virtually pre-existing constants.)
1071 return phase->zerocon(memory_type());
1072 }
1073
1074 // A load from an initialization barrier can match a captured store.
1075 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1076 InitializeNode* init = st->in(0)->as_Initialize();
1077 AllocateNode* alloc = init->allocation();
1078 if ((alloc != NULL) && (alloc == ld_alloc)) {
1079 // examine a captured store value
1080 st = init->find_captured_store(ld_off, memory_size(), phase);
1081 if (st != NULL)
1082 continue; // take one more trip around
1083 }
1084 }
1085
1086 // Load boxed value from result of valueOf() call is input parameter.
1087 if (this->is_Load() && ld_adr->is_AddP() &&
1088 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1089 intptr_t ignore = 0;
1090 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1091 if (base != NULL && base->is_Proj() &&
1092 base->as_Proj()->_con == TypeFunc::Parms &&
1093 base->in(0)->is_CallStaticJava() &&
1094 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1095 return base->in(0)->in(TypeFunc::Parms);
1096 }
1097 }
1098
1099 break;
1100 }
1101
1102 return NULL;
1103 }
1104
1105 //----------------------is_instance_field_load_with_local_phi------------------
1106 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1107 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1108 in(Address)->is_AddP() ) {
1109 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1110 // Only instances and boxed values.
1111 if( t_oop != NULL &&
1112 (t_oop->is_ptr_to_boxed_value() ||
1113 t_oop->is_known_instance_field()) &&
1114 t_oop->offset() != Type::OffsetBot &&
1115 t_oop->offset() != Type::OffsetTop) {
1116 return true;
1117 }
1118 }
1119 return false;
1120 }
1121
1122 //------------------------------Identity---------------------------------------
1123 // Loads are identity if previous store is to same address
1124 Node *LoadNode::Identity( PhaseTransform *phase ) {
1125 // If the previous store-maker is the right kind of Store, and the store is
1126 // to the same address, then we are equal to the value stored.
1127 Node* mem = in(Memory);
1128 Node* value = can_see_stored_value(mem, phase);
1129 if( value ) {
1130 // byte, short & char stores truncate naturally.
1131 // A load has to load the truncated value which requires
1132 // some sort of masking operation and that requires an
1133 // Ideal call instead of an Identity call.
1134 if (memory_size() < BytesPerInt) {
1135 // If the input to the store does not fit with the load's result type,
1136 // it must be truncated via an Ideal call.
1137 if (!phase->type(value)->higher_equal(phase->type(this)))
1138 return this;
1139 }
1140 // (This works even when value is a Con, but LoadNode::Value
1141 // usually runs first, producing the singleton type of the Con.)
1142 return value;
1143 }
1144
1145 // Search for an existing data phi which was generated before for the same
1146 // instance's field to avoid infinite generation of phis in a loop.
1147 Node *region = mem->in(0);
1148 if (is_instance_field_load_with_local_phi(region)) {
1149 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1150 int this_index = phase->C->get_alias_index(addr_t);
1151 int this_offset = addr_t->offset();
1152 int this_iid = addr_t->instance_id();
1153 if (!addr_t->is_known_instance() &&
1154 addr_t->is_ptr_to_boxed_value()) {
1155 // Use _idx of address base (could be Phi node) for boxed values.
1156 intptr_t ignore = 0;
1157 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1158 this_iid = base->_idx;
1159 }
1160 const Type* this_type = bottom_type();
1161 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1162 Node* phi = region->fast_out(i);
1163 if (phi->is_Phi() && phi != mem &&
1164 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1165 return phi;
1166 }
1167 }
1168 }
1169
1170 return this;
1171 }
1172
1173 // We're loading from an object which has autobox behaviour.
1174 // If this object is result of a valueOf call we'll have a phi
1175 // merging a newly allocated object and a load from the cache.
1176 // We want to replace this load with the original incoming
1177 // argument to the valueOf call.
1178 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1179 assert(phase->C->eliminate_boxing(), "sanity");
1180 intptr_t ignore = 0;
1181 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1182 if ((base == NULL) || base->is_Phi()) {
1183 // Push the loads from the phi that comes from valueOf up
1184 // through it to allow elimination of the loads and the recovery
1185 // of the original value. It is done in split_through_phi().
1186 return NULL;
1187 } else if (base->is_Load() ||
1188 base->is_DecodeN() && base->in(1)->is_Load()) {
1189 // Eliminate the load of boxed value for integer types from the cache
1190 // array by deriving the value from the index into the array.
1191 // Capture the offset of the load and then reverse the computation.
1192
1193 // Get LoadN node which loads a boxing object from 'cache' array.
1194 if (base->is_DecodeN()) {
1195 base = base->in(1);
1196 }
1197 if (!base->in(Address)->is_AddP()) {
1198 return NULL; // Complex address
1199 }
1200 AddPNode* address = base->in(Address)->as_AddP();
1201 Node* cache_base = address->in(AddPNode::Base);
1202 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1203 // Get ConP node which is static 'cache' field.
1204 cache_base = cache_base->in(1);
1205 }
1206 if ((cache_base != NULL) && cache_base->is_Con()) {
1207 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1208 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1209 Node* elements[4];
1210 int shift = exact_log2(type2aelembytes(T_OBJECT));
1211 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1212 if ((count > 0) && elements[0]->is_Con() &&
1213 ((count == 1) ||
1214 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1215 elements[1]->in(2) == phase->intcon(shift))) {
1216 ciObjArray* array = base_type->const_oop()->as_obj_array();
1217 // Fetch the box object cache[0] at the base of the array and get its value
1218 ciInstance* box = array->obj_at(0)->as_instance();
1219 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1220 assert(ik->is_box_klass(), "sanity");
1221 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1222 if (ik->nof_nonstatic_fields() == 1) {
1223 // This should be true nonstatic_field_at requires calling
1224 // nof_nonstatic_fields so check it anyway
1225 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1226 BasicType bt = c.basic_type();
1227 // Only integer types have boxing cache.
1228 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1229 bt == T_BYTE || bt == T_SHORT ||
1230 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1231 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1232 if (cache_low != (int)cache_low) {
1233 return NULL; // should not happen since cache is array indexed by value
1234 }
1235 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1236 if (offset != (int)offset) {
1237 return NULL; // should not happen since cache is array indexed by value
1238 }
1239 // Add up all the offsets making of the address of the load
1240 Node* result = elements[0];
1241 for (int i = 1; i < count; i++) {
1242 result = phase->transform(new (phase->C) AddXNode(result, elements[i]));
1243 }
1244 // Remove the constant offset from the address and then
1245 result = phase->transform(new (phase->C) AddXNode(result, phase->MakeConX(-(int)offset)));
1246 // remove the scaling of the offset to recover the original index.
1247 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1248 // Peel the shift off directly but wrap it in a dummy node
1249 // since Ideal can't return existing nodes
1250 result = new (phase->C) RShiftXNode(result->in(1), phase->intcon(0));
1251 } else if (result->is_Add() && result->in(2)->is_Con() &&
1252 result->in(1)->Opcode() == Op_LShiftX &&
1253 result->in(1)->in(2) == phase->intcon(shift)) {
1254 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1255 // but for boxing cache access we know that X<<Z will not overflow
1256 // (there is range check) so we do this optimizatrion by hand here.
1257 Node* add_con = new (phase->C) RShiftXNode(result->in(2), phase->intcon(shift));
1258 result = new (phase->C) AddXNode(result->in(1)->in(1), phase->transform(add_con));
1259 } else {
1260 result = new (phase->C) RShiftXNode(result, phase->intcon(shift));
1261 }
1262 #ifdef _LP64
1263 if (bt != T_LONG) {
1264 result = new (phase->C) ConvL2INode(phase->transform(result));
1265 }
1266 #else
1267 if (bt == T_LONG) {
1268 result = new (phase->C) ConvI2LNode(phase->transform(result));
1269 }
1270 #endif
1271 return result;
1272 }
1273 }
1274 }
1275 }
1276 }
1277 return NULL;
1278 }
1279
1280 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1281 Node* region = phi->in(0);
1282 if (region == NULL) {
1283 return false; // Wait stable graph
1284 }
1285 uint cnt = phi->req();
1286 for (uint i = 1; i < cnt; i++) {
1287 Node* rc = region->in(i);
1288 if (rc == NULL || phase->type(rc) == Type::TOP)
1289 return false; // Wait stable graph
1290 Node* in = phi->in(i);
1291 if (in == NULL || phase->type(in) == Type::TOP)
1292 return false; // Wait stable graph
1293 }
1294 return true;
1295 }
1296 //------------------------------split_through_phi------------------------------
1297 // Split instance or boxed field load through Phi.
1298 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1299 Node* mem = in(Memory);
1300 Node* address = in(Address);
1301 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1302
1303 assert((t_oop != NULL) &&
1304 (t_oop->is_known_instance_field() ||
1305 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1306
1307 Compile* C = phase->C;
1308 intptr_t ignore = 0;
1309 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1310 bool base_is_phi = (base != NULL) && base->is_Phi();
1311 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1312 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1313 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1314
1315 if (!((mem->is_Phi() || base_is_phi) &&
1316 (load_boxed_values || t_oop->is_known_instance_field()))) {
1317 return NULL; // memory is not Phi
1318 }
1319
1320 if (mem->is_Phi()) {
1321 if (!stable_phi(mem->as_Phi(), phase)) {
1322 return NULL; // Wait stable graph
1323 }
1324 uint cnt = mem->req();
1325 // Check for loop invariant memory.
1326 if (cnt == 3) {
1327 for (uint i = 1; i < cnt; i++) {
1328 Node* in = mem->in(i);
1329 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1330 if (m == mem) {
1331 set_req(Memory, mem->in(cnt - i));
1332 return this; // made change
1333 }
1334 }
1335 }
1336 }
1337 if (base_is_phi) {
1338 if (!stable_phi(base->as_Phi(), phase)) {
1339 return NULL; // Wait stable graph
1340 }
1341 uint cnt = base->req();
1342 // Check for loop invariant memory.
1343 if (cnt == 3) {
1344 for (uint i = 1; i < cnt; i++) {
1345 if (base->in(i) == base) {
1346 return NULL; // Wait stable graph
1347 }
1348 }
1349 }
1350 }
1351
1352 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1353
1354 // Split through Phi (see original code in loopopts.cpp).
1355 assert(C->have_alias_type(t_oop), "instance should have alias type");
1356
1357 // Do nothing here if Identity will find a value
1358 // (to avoid infinite chain of value phis generation).
1359 if (!phase->eqv(this, this->Identity(phase)))
1360 return NULL;
1361
1362 // Select Region to split through.
1363 Node* region;
1364 if (!base_is_phi) {
1365 assert(mem->is_Phi(), "sanity");
1366 region = mem->in(0);
1367 // Skip if the region dominates some control edge of the address.
1368 if (!MemNode::all_controls_dominate(address, region))
1369 return NULL;
1370 } else if (!mem->is_Phi()) {
1371 assert(base_is_phi, "sanity");
1372 region = base->in(0);
1373 // Skip if the region dominates some control edge of the memory.
1374 if (!MemNode::all_controls_dominate(mem, region))
1375 return NULL;
1376 } else if (base->in(0) != mem->in(0)) {
1377 assert(base_is_phi && mem->is_Phi(), "sanity");
1378 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1379 region = base->in(0);
1380 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1381 region = mem->in(0);
1382 } else {
1383 return NULL; // complex graph
1384 }
1385 } else {
1386 assert(base->in(0) == mem->in(0), "sanity");
1387 region = mem->in(0);
1388 }
1389
1390 const Type* this_type = this->bottom_type();
1391 int this_index = C->get_alias_index(t_oop);
1392 int this_offset = t_oop->offset();
1393 int this_iid = t_oop->instance_id();
1394 if (!t_oop->is_known_instance() && load_boxed_values) {
1395 // Use _idx of address base for boxed values.
1396 this_iid = base->_idx;
1397 }
1398 PhaseIterGVN* igvn = phase->is_IterGVN();
1399 Node* phi = new (C) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1400 for (uint i = 1; i < region->req(); i++) {
1401 Node* x;
1402 Node* the_clone = NULL;
1403 if (region->in(i) == C->top()) {
1404 x = C->top(); // Dead path? Use a dead data op
1405 } else {
1406 x = this->clone(); // Else clone up the data op
1407 the_clone = x; // Remember for possible deletion.
1408 // Alter data node to use pre-phi inputs
1409 if (this->in(0) == region) {
1410 x->set_req(0, region->in(i));
1411 } else {
1412 x->set_req(0, NULL);
1413 }
1414 if (mem->is_Phi() && (mem->in(0) == region)) {
1415 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1416 }
1417 if (address->is_Phi() && address->in(0) == region) {
1418 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1419 }
1420 if (base_is_phi && (base->in(0) == region)) {
1421 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1422 Node* adr_x = phase->transform(new (C) AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1423 x->set_req(Address, adr_x);
1424 }
1425 }
1426 // Check for a 'win' on some paths
1427 const Type *t = x->Value(igvn);
1428
1429 bool singleton = t->singleton();
1430
1431 // See comments in PhaseIdealLoop::split_thru_phi().
1432 if (singleton && t == Type::TOP) {
1433 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1434 }
1435
1436 if (singleton) {
1437 x = igvn->makecon(t);
1438 } else {
1439 // We now call Identity to try to simplify the cloned node.
1440 // Note that some Identity methods call phase->type(this).
1441 // Make sure that the type array is big enough for
1442 // our new node, even though we may throw the node away.
1443 // (This tweaking with igvn only works because x is a new node.)
1444 igvn->set_type(x, t);
1445 // If x is a TypeNode, capture any more-precise type permanently into Node
1446 // otherwise it will be not updated during igvn->transform since
1447 // igvn->type(x) is set to x->Value() already.
1448 x->raise_bottom_type(t);
1449 Node *y = x->Identity(igvn);
1450 if (y != x) {
1451 x = y;
1452 } else {
1453 y = igvn->hash_find_insert(x);
1454 if (y) {
1455 x = y;
1456 } else {
1457 // Else x is a new node we are keeping
1458 // We do not need register_new_node_with_optimizer
1459 // because set_type has already been called.
1460 igvn->_worklist.push(x);
1461 }
1462 }
1463 }
1464 if (x != the_clone && the_clone != NULL) {
1465 igvn->remove_dead_node(the_clone);
1466 }
1467 phi->set_req(i, x);
1468 }
1469 // Record Phi
1470 igvn->register_new_node_with_optimizer(phi);
1471 return phi;
1472 }
1473
1474 //------------------------------Ideal------------------------------------------
1475 // If the load is from Field memory and the pointer is non-null, we can
1476 // zero out the control input.
1477 // If the offset is constant and the base is an object allocation,
1478 // try to hook me up to the exact initializing store.
1479 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1480 Node* p = MemNode::Ideal_common(phase, can_reshape);
1481 if (p) return (p == NodeSentinel) ? NULL : p;
1482
1483 Node* ctrl = in(MemNode::Control);
1484 Node* address = in(MemNode::Address);
1485
1486 // Skip up past a SafePoint control. Cannot do this for Stores because
1487 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1488 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1489 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1490 ctrl = ctrl->in(0);
1491 set_req(MemNode::Control,ctrl);
1492 }
1493
1494 intptr_t ignore = 0;
1495 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1496 if (base != NULL
1497 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1498 // Check for useless control edge in some common special cases
1499 if (in(MemNode::Control) != NULL
1500 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1501 && all_controls_dominate(base, phase->C->start())) {
1502 // A method-invariant, non-null address (constant or 'this' argument).
1503 set_req(MemNode::Control, NULL);
1504 }
1505 }
1506
1507 Node* mem = in(MemNode::Memory);
1508 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1509
1510 if (can_reshape && (addr_t != NULL)) {
1511 // try to optimize our memory input
1512 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1513 if (opt_mem != mem) {
1514 set_req(MemNode::Memory, opt_mem);
1515 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1516 return this;
1517 }
1518 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1519 if ((t_oop != NULL) &&
1520 (t_oop->is_known_instance_field() ||
1521 t_oop->is_ptr_to_boxed_value())) {
1522 PhaseIterGVN *igvn = phase->is_IterGVN();
1523 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1524 // Delay this transformation until memory Phi is processed.
1525 phase->is_IterGVN()->_worklist.push(this);
1526 return NULL;
1527 }
1528 // Split instance field load through Phi.
1529 Node* result = split_through_phi(phase);
1530 if (result != NULL) return result;
1531
1532 if (t_oop->is_ptr_to_boxed_value()) {
1533 Node* result = eliminate_autobox(phase);
1534 if (result != NULL) return result;
1535 }
1536 }
1537 }
1538
1539 // Check for prior store with a different base or offset; make Load
1540 // independent. Skip through any number of them. Bail out if the stores
1541 // are in an endless dead cycle and report no progress. This is a key
1542 // transform for Reflection. However, if after skipping through the Stores
1543 // we can't then fold up against a prior store do NOT do the transform as
1544 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1545 // array memory alive twice: once for the hoisted Load and again after the
1546 // bypassed Store. This situation only works if EVERYBODY who does
1547 // anti-dependence work knows how to bypass. I.e. we need all
1548 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1549 // the alias index stuff. So instead, peek through Stores and IFF we can
1550 // fold up, do so.
1551 Node* prev_mem = find_previous_store(phase);
1552 // Steps (a), (b): Walk past independent stores to find an exact match.
1553 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1554 // (c) See if we can fold up on the spot, but don't fold up here.
1555 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1556 // just return a prior value, which is done by Identity calls.
1557 if (can_see_stored_value(prev_mem, phase)) {
1558 // Make ready for step (d):
1559 set_req(MemNode::Memory, prev_mem);
1560 return this;
1561 }
1562 }
1563
1564 return NULL; // No further progress
1565 }
1566
1567 // Helper to recognize certain Klass fields which are invariant across
1568 // some group of array types (e.g., int[] or all T[] where T < Object).
1569 const Type*
1570 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1571 ciKlass* klass) const {
1572 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1573 // The field is Klass::_modifier_flags. Return its (constant) value.
1574 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1575 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1576 return TypeInt::make(klass->modifier_flags());
1577 }
1578 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1579 // The field is Klass::_access_flags. Return its (constant) value.
1580 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1581 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1582 return TypeInt::make(klass->access_flags());
1583 }
1584 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1585 // The field is Klass::_layout_helper. Return its constant value if known.
1586 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1587 return TypeInt::make(klass->layout_helper());
1588 }
1589
1590 // No match.
1591 return NULL;
1592 }
1593
1594 // Try to constant-fold a stable array element.
1595 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1596 assert(ary->const_oop(), "array should be constant");
1597 assert(ary->is_stable(), "array should be stable");
1598
1599 // Decode the results of GraphKit::array_element_address.
1600 ciArray* aobj = ary->const_oop()->as_array();
1601 ciConstant con = aobj->element_value_by_offset(off);
1602
1603 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1604 const Type* con_type = Type::make_from_constant(con);
1605 if (con_type != NULL) {
1606 if (con_type->isa_aryptr()) {
1607 // Join with the array element type, in case it is also stable.
1608 int dim = ary->stable_dimension();
1609 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1610 }
1611 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1612 con_type = con_type->make_narrowoop();
1613 }
1614 #ifndef PRODUCT
1615 if (TraceIterativeGVN) {
1616 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1617 con_type->dump(); tty->cr();
1618 }
1619 #endif //PRODUCT
1620 return con_type;
1621 }
1622 }
1623 return NULL;
1624 }
1625
1626 //------------------------------Value-----------------------------------------
1627 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1628 // Either input is TOP ==> the result is TOP
1629 Node* mem = in(MemNode::Memory);
1630 const Type *t1 = phase->type(mem);
1631 if (t1 == Type::TOP) return Type::TOP;
1632 Node* adr = in(MemNode::Address);
1633 const TypePtr* tp = phase->type(adr)->isa_ptr();
1634 if (tp == NULL || tp->empty()) return Type::TOP;
1635 int off = tp->offset();
1636 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1637 Compile* C = phase->C;
1638
1639 // Try to guess loaded type from pointer type
1640 if (tp->isa_aryptr()) {
1641 const TypeAryPtr* ary = tp->is_aryptr();
1642 const Type* t = ary->elem();
1643
1644 // Determine whether the reference is beyond the header or not, by comparing
1645 // the offset against the offset of the start of the array's data.
1646 // Different array types begin at slightly different offsets (12 vs. 16).
1647 // We choose T_BYTE as an example base type that is least restrictive
1648 // as to alignment, which will therefore produce the smallest
1649 // possible base offset.
1650 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1651 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1652
1653 // Try to constant-fold a stable array element.
1654 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1655 // Make sure the reference is not into the header and the offset is constant
1656 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1657 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1658 if (con_type != NULL) {
1659 return con_type;
1660 }
1661 }
1662 }
1663
1664 // Don't do this for integer types. There is only potential profit if
1665 // the element type t is lower than _type; that is, for int types, if _type is
1666 // more restrictive than t. This only happens here if one is short and the other
1667 // char (both 16 bits), and in those cases we've made an intentional decision
1668 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1669 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1670 //
1671 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1672 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1673 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1674 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1675 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1676 // In fact, that could have been the original type of p1, and p1 could have
1677 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1678 // expression (LShiftL quux 3) independently optimized to the constant 8.
1679 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1680 && (_type->isa_vect() == NULL)
1681 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1682 // t might actually be lower than _type, if _type is a unique
1683 // concrete subclass of abstract class t.
1684 if (off_beyond_header) { // is the offset beyond the header?
1685 const Type* jt = t->join_speculative(_type);
1686 // In any case, do not allow the join, per se, to empty out the type.
1687 if (jt->empty() && !t->empty()) {
1688 // This can happen if a interface-typed array narrows to a class type.
1689 jt = _type;
1690 }
1691 #ifdef ASSERT
1692 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1693 // The pointers in the autobox arrays are always non-null
1694 Node* base = adr->in(AddPNode::Base);
1695 if ((base != NULL) && base->is_DecodeN()) {
1696 // Get LoadN node which loads IntegerCache.cache field
1697 base = base->in(1);
1698 }
1699 if ((base != NULL) && base->is_Con()) {
1700 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1701 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1702 // It could be narrow oop
1703 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1704 }
1705 }
1706 }
1707 #endif
1708 return jt;
1709 }
1710 }
1711 } else if (tp->base() == Type::InstPtr) {
1712 ciEnv* env = C->env();
1713 const TypeInstPtr* tinst = tp->is_instptr();
1714 ciKlass* klass = tinst->klass();
1715 assert( off != Type::OffsetBot ||
1716 // arrays can be cast to Objects
1717 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1718 // unsafe field access may not have a constant offset
1719 C->has_unsafe_access(),
1720 "Field accesses must be precise" );
1721 // For oop loads, we expect the _type to be precise
1722 if (klass == env->String_klass() &&
1723 adr->is_AddP() && off != Type::OffsetBot) {
1724 // For constant Strings treat the final fields as compile time constants.
1725 Node* base = adr->in(AddPNode::Base);
1726 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1727 if (t != NULL && t->singleton()) {
1728 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1729 if (field != NULL && field->is_final()) {
1730 ciObject* string = t->const_oop();
1731 ciConstant constant = string->as_instance()->field_value(field);
1732 if (constant.basic_type() == T_INT) {
1733 return TypeInt::make(constant.as_int());
1734 } else if (constant.basic_type() == T_ARRAY) {
1735 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1736 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1737 } else {
1738 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1739 }
1740 }
1741 }
1742 }
1743 }
1744 // Optimizations for constant objects
1745 ciObject* const_oop = tinst->const_oop();
1746 if (const_oop != NULL) {
1747 // For constant Boxed value treat the target field as a compile time constant.
1748 if (tinst->is_ptr_to_boxed_value()) {
1749 return tinst->get_const_boxed_value();
1750 } else
1751 // For constant CallSites treat the target field as a compile time constant.
1752 if (const_oop->is_call_site()) {
1753 ciCallSite* call_site = const_oop->as_call_site();
1754 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1755 if (field != NULL && field->is_call_site_target()) {
1756 ciMethodHandle* target = call_site->get_target();
1757 if (target != NULL) { // just in case
1758 ciConstant constant(T_OBJECT, target);
1759 const Type* t;
1760 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1761 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1762 } else {
1763 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1764 }
1765 // Add a dependence for invalidation of the optimization.
1766 if (!call_site->is_constant_call_site()) {
1767 C->dependencies()->assert_call_site_target_value(call_site, target);
1768 }
1769 return t;
1770 }
1771 }
1772 }
1773 }
1774 } else if (tp->base() == Type::KlassPtr) {
1775 assert( off != Type::OffsetBot ||
1776 // arrays can be cast to Objects
1777 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1778 // also allow array-loading from the primary supertype
1779 // array during subtype checks
1780 Opcode() == Op_LoadKlass,
1781 "Field accesses must be precise" );
1782 // For klass/static loads, we expect the _type to be precise
1783 }
1784
1785 const TypeKlassPtr *tkls = tp->isa_klassptr();
1786 if (tkls != NULL && !StressReflectiveCode) {
1787 ciKlass* klass = tkls->klass();
1788 if (klass->is_loaded() && tkls->klass_is_exact()) {
1789 // We are loading a field from a Klass metaobject whose identity
1790 // is known at compile time (the type is "exact" or "precise").
1791 // Check for fields we know are maintained as constants by the VM.
1792 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1793 // The field is Klass::_super_check_offset. Return its (constant) value.
1794 // (Folds up type checking code.)
1795 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1796 return TypeInt::make(klass->super_check_offset());
1797 }
1798 // Compute index into primary_supers array
1799 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1800 // Check for overflowing; use unsigned compare to handle the negative case.
1801 if( depth < ciKlass::primary_super_limit() ) {
1802 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1803 // (Folds up type checking code.)
1804 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1805 ciKlass *ss = klass->super_of_depth(depth);
1806 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1807 }
1808 const Type* aift = load_array_final_field(tkls, klass);
1809 if (aift != NULL) return aift;
1810 if (tkls->offset() == in_bytes(ArrayKlass::component_mirror_offset())
1811 && klass->is_array_klass()) {
1812 // The field is ArrayKlass::_component_mirror. Return its (constant) value.
1813 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1814 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1815 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1816 }
1817 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1818 // The field is Klass::_java_mirror. Return its (constant) value.
1819 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1820 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1821 return TypeInstPtr::make(klass->java_mirror());
1822 }
1823 }
1824
1825 // We can still check if we are loading from the primary_supers array at a
1826 // shallow enough depth. Even though the klass is not exact, entries less
1827 // than or equal to its super depth are correct.
1828 if (klass->is_loaded() ) {
1829 ciType *inner = klass;
1830 while( inner->is_obj_array_klass() )
1831 inner = inner->as_obj_array_klass()->base_element_type();
1832 if( inner->is_instance_klass() &&
1833 !inner->as_instance_klass()->flags().is_interface() ) {
1834 // Compute index into primary_supers array
1835 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1836 // Check for overflowing; use unsigned compare to handle the negative case.
1837 if( depth < ciKlass::primary_super_limit() &&
1838 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1839 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1840 // (Folds up type checking code.)
1841 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1842 ciKlass *ss = klass->super_of_depth(depth);
1843 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1844 }
1845 }
1846 }
1847
1848 // If the type is enough to determine that the thing is not an array,
1849 // we can give the layout_helper a positive interval type.
1850 // This will help short-circuit some reflective code.
1851 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1852 && !klass->is_array_klass() // not directly typed as an array
1853 && !klass->is_interface() // specifically not Serializable & Cloneable
1854 && !klass->is_java_lang_Object() // not the supertype of all T[]
1855 ) {
1856 // Note: When interfaces are reliable, we can narrow the interface
1857 // test to (klass != Serializable && klass != Cloneable).
1858 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1859 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1860 // The key property of this type is that it folds up tests
1861 // for array-ness, since it proves that the layout_helper is positive.
1862 // Thus, a generic value like the basic object layout helper works fine.
1863 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1864 }
1865 }
1866
1867 // If we are loading from a freshly-allocated object, produce a zero,
1868 // if the load is provably beyond the header of the object.
1869 // (Also allow a variable load from a fresh array to produce zero.)
1870 const TypeOopPtr *tinst = tp->isa_oopptr();
1871 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1872 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1873 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1874 Node* value = can_see_stored_value(mem,phase);
1875 if (value != NULL && value->is_Con()) {
1876 assert(value->bottom_type()->higher_equal(_type),"sanity");
1877 return value->bottom_type();
1878 }
1879 }
1880
1881 if (is_instance) {
1882 // If we have an instance type and our memory input is the
1883 // programs's initial memory state, there is no matching store,
1884 // so just return a zero of the appropriate type
1885 Node *mem = in(MemNode::Memory);
1886 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1887 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1888 return Type::get_zero_type(_type->basic_type());
1889 }
1890 }
1891 return _type;
1892 }
1893
1894 //------------------------------match_edge-------------------------------------
1895 // Do we Match on this edge index or not? Match only the address.
1896 uint LoadNode::match_edge(uint idx) const {
1897 return idx == MemNode::Address;
1898 }
1899
1900 //--------------------------LoadBNode::Ideal--------------------------------------
1901 //
1902 // If the previous store is to the same address as this load,
1903 // and the value stored was larger than a byte, replace this load
1904 // with the value stored truncated to a byte. If no truncation is
1905 // needed, the replacement is done in LoadNode::Identity().
1906 //
1907 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1908 Node* mem = in(MemNode::Memory);
1909 Node* value = can_see_stored_value(mem,phase);
1910 if( value && !phase->type(value)->higher_equal( _type ) ) {
1911 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(24)) );
1912 return new (phase->C) RShiftINode(result, phase->intcon(24));
1913 }
1914 // Identity call will handle the case where truncation is not needed.
1915 return LoadNode::Ideal(phase, can_reshape);
1916 }
1917
1918 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1919 Node* mem = in(MemNode::Memory);
1920 Node* value = can_see_stored_value(mem,phase);
1921 if (value != NULL && value->is_Con() &&
1922 !value->bottom_type()->higher_equal(_type)) {
1923 // If the input to the store does not fit with the load's result type,
1924 // it must be truncated. We can't delay until Ideal call since
1925 // a singleton Value is needed for split_thru_phi optimization.
1926 int con = value->get_int();
1927 return TypeInt::make((con << 24) >> 24);
1928 }
1929 return LoadNode::Value(phase);
1930 }
1931
1932 //--------------------------LoadUBNode::Ideal-------------------------------------
1933 //
1934 // If the previous store is to the same address as this load,
1935 // and the value stored was larger than a byte, replace this load
1936 // with the value stored truncated to a byte. If no truncation is
1937 // needed, the replacement is done in LoadNode::Identity().
1938 //
1939 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1940 Node* mem = in(MemNode::Memory);
1941 Node* value = can_see_stored_value(mem, phase);
1942 if (value && !phase->type(value)->higher_equal(_type))
1943 return new (phase->C) AndINode(value, phase->intcon(0xFF));
1944 // Identity call will handle the case where truncation is not needed.
1945 return LoadNode::Ideal(phase, can_reshape);
1946 }
1947
1948 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1949 Node* mem = in(MemNode::Memory);
1950 Node* value = can_see_stored_value(mem,phase);
1951 if (value != NULL && value->is_Con() &&
1952 !value->bottom_type()->higher_equal(_type)) {
1953 // If the input to the store does not fit with the load's result type,
1954 // it must be truncated. We can't delay until Ideal call since
1955 // a singleton Value is needed for split_thru_phi optimization.
1956 int con = value->get_int();
1957 return TypeInt::make(con & 0xFF);
1958 }
1959 return LoadNode::Value(phase);
1960 }
1961
1962 //--------------------------LoadUSNode::Ideal-------------------------------------
1963 //
1964 // If the previous store is to the same address as this load,
1965 // and the value stored was larger than a char, replace this load
1966 // with the value stored truncated to a char. If no truncation is
1967 // needed, the replacement is done in LoadNode::Identity().
1968 //
1969 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1970 Node* mem = in(MemNode::Memory);
1971 Node* value = can_see_stored_value(mem,phase);
1972 if( value && !phase->type(value)->higher_equal( _type ) )
1973 return new (phase->C) AndINode(value,phase->intcon(0xFFFF));
1974 // Identity call will handle the case where truncation is not needed.
1975 return LoadNode::Ideal(phase, can_reshape);
1976 }
1977
1978 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1979 Node* mem = in(MemNode::Memory);
1980 Node* value = can_see_stored_value(mem,phase);
1981 if (value != NULL && value->is_Con() &&
1982 !value->bottom_type()->higher_equal(_type)) {
1983 // If the input to the store does not fit with the load's result type,
1984 // it must be truncated. We can't delay until Ideal call since
1985 // a singleton Value is needed for split_thru_phi optimization.
1986 int con = value->get_int();
1987 return TypeInt::make(con & 0xFFFF);
1988 }
1989 return LoadNode::Value(phase);
1990 }
1991
1992 //--------------------------LoadSNode::Ideal--------------------------------------
1993 //
1994 // If the previous store is to the same address as this load,
1995 // and the value stored was larger than a short, replace this load
1996 // with the value stored truncated to a short. If no truncation is
1997 // needed, the replacement is done in LoadNode::Identity().
1998 //
1999 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2000 Node* mem = in(MemNode::Memory);
2001 Node* value = can_see_stored_value(mem,phase);
2002 if( value && !phase->type(value)->higher_equal( _type ) ) {
2003 Node *result = phase->transform( new (phase->C) LShiftINode(value, phase->intcon(16)) );
2004 return new (phase->C) RShiftINode(result, phase->intcon(16));
2005 }
2006 // Identity call will handle the case where truncation is not needed.
2007 return LoadNode::Ideal(phase, can_reshape);
2008 }
2009
2010 const Type* LoadSNode::Value(PhaseTransform *phase) const {
2011 Node* mem = in(MemNode::Memory);
2012 Node* value = can_see_stored_value(mem,phase);
2013 if (value != NULL && value->is_Con() &&
2014 !value->bottom_type()->higher_equal(_type)) {
2015 // If the input to the store does not fit with the load's result type,
2016 // it must be truncated. We can't delay until Ideal call since
2017 // a singleton Value is needed for split_thru_phi optimization.
2018 int con = value->get_int();
2019 return TypeInt::make((con << 16) >> 16);
2020 }
2021 return LoadNode::Value(phase);
2022 }
2023
2024 //=============================================================================
2025 //----------------------------LoadKlassNode::make------------------------------
2026 // Polymorphic factory method:
2027 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
2028 Compile* C = gvn.C;
2029 Node *ctl = NULL;
2030 // sanity check the alias category against the created node type
2031 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2032 assert(adr_type != NULL, "expecting TypeKlassPtr");
2033 #ifdef _LP64
2034 if (adr_type->is_ptr_to_narrowklass()) {
2035 assert(UseCompressedClassPointers, "no compressed klasses");
2036 Node* load_klass = gvn.transform(new (C) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2037 return new (C) DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2038 }
2039 #endif
2040 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2041 return new (C) LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2042 }
2043
2044 //------------------------------Value------------------------------------------
2045 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
2046 return klass_value_common(phase);
2047 }
2048
2049 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2050 // Either input is TOP ==> the result is TOP
2051 const Type *t1 = phase->type( in(MemNode::Memory) );
2052 if (t1 == Type::TOP) return Type::TOP;
2053 Node *adr = in(MemNode::Address);
2054 const Type *t2 = phase->type( adr );
2055 if (t2 == Type::TOP) return Type::TOP;
2056 const TypePtr *tp = t2->is_ptr();
2057 if (TypePtr::above_centerline(tp->ptr()) ||
2058 tp->ptr() == TypePtr::Null) return Type::TOP;
2059
2060 // Return a more precise klass, if possible
2061 const TypeInstPtr *tinst = tp->isa_instptr();
2062 if (tinst != NULL) {
2063 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2064 int offset = tinst->offset();
2065 if (ik == phase->C->env()->Class_klass()
2066 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2067 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2068 // We are loading a special hidden field from a Class mirror object,
2069 // the field which points to the VM's Klass metaobject.
2070 ciType* t = tinst->java_mirror_type();
2071 // java_mirror_type returns non-null for compile-time Class constants.
2072 if (t != NULL) {
2073 // constant oop => constant klass
2074 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2075 if (t->is_void()) {
2076 // We cannot create a void array. Since void is a primitive type return null
2077 // klass. Users of this result need to do a null check on the returned klass.
2078 return TypePtr::NULL_PTR;
2079 }
2080 return TypeKlassPtr::make(ciArrayKlass::make(t));
2081 }
2082 if (!t->is_klass()) {
2083 // a primitive Class (e.g., int.class) has NULL for a klass field
2084 return TypePtr::NULL_PTR;
2085 }
2086 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2087 return TypeKlassPtr::make(t->as_klass());
2088 }
2089 // non-constant mirror, so we can't tell what's going on
2090 }
2091 if( !ik->is_loaded() )
2092 return _type; // Bail out if not loaded
2093 if (offset == oopDesc::klass_offset_in_bytes()) {
2094 if (tinst->klass_is_exact()) {
2095 return TypeKlassPtr::make(ik);
2096 }
2097 // See if we can become precise: no subklasses and no interface
2098 // (Note: We need to support verified interfaces.)
2099 if (!ik->is_interface() && !ik->has_subklass()) {
2100 //assert(!UseExactTypes, "this code should be useless with exact types");
2101 // Add a dependence; if any subclass added we need to recompile
2102 if (!ik->is_final()) {
2103 // %%% should use stronger assert_unique_concrete_subtype instead
2104 phase->C->dependencies()->assert_leaf_type(ik);
2105 }
2106 // Return precise klass
2107 return TypeKlassPtr::make(ik);
2108 }
2109
2110 // Return root of possible klass
2111 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2112 }
2113 }
2114
2115 // Check for loading klass from an array
2116 const TypeAryPtr *tary = tp->isa_aryptr();
2117 if( tary != NULL ) {
2118 ciKlass *tary_klass = tary->klass();
2119 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2120 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2121 if (tary->klass_is_exact()) {
2122 return TypeKlassPtr::make(tary_klass);
2123 }
2124 ciArrayKlass *ak = tary->klass()->as_array_klass();
2125 // If the klass is an object array, we defer the question to the
2126 // array component klass.
2127 if( ak->is_obj_array_klass() ) {
2128 assert( ak->is_loaded(), "" );
2129 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2130 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2131 ciInstanceKlass* ik = base_k->as_instance_klass();
2132 // See if we can become precise: no subklasses and no interface
2133 if (!ik->is_interface() && !ik->has_subklass()) {
2134 //assert(!UseExactTypes, "this code should be useless with exact types");
2135 // Add a dependence; if any subclass added we need to recompile
2136 if (!ik->is_final()) {
2137 phase->C->dependencies()->assert_leaf_type(ik);
2138 }
2139 // Return precise array klass
2140 return TypeKlassPtr::make(ak);
2141 }
2142 }
2143 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2144 } else { // Found a type-array?
2145 //assert(!UseExactTypes, "this code should be useless with exact types");
2146 assert( ak->is_type_array_klass(), "" );
2147 return TypeKlassPtr::make(ak); // These are always precise
2148 }
2149 }
2150 }
2151
2152 // Check for loading klass from an array klass
2153 const TypeKlassPtr *tkls = tp->isa_klassptr();
2154 if (tkls != NULL && !StressReflectiveCode) {
2155 ciKlass* klass = tkls->klass();
2156 if( !klass->is_loaded() )
2157 return _type; // Bail out if not loaded
2158 if( klass->is_obj_array_klass() &&
2159 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2160 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2161 // // Always returning precise element type is incorrect,
2162 // // e.g., element type could be object and array may contain strings
2163 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2164
2165 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2166 // according to the element type's subclassing.
2167 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2168 }
2169 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2170 tkls->offset() == in_bytes(Klass::super_offset())) {
2171 ciKlass* sup = klass->as_instance_klass()->super();
2172 // The field is Klass::_super. Return its (constant) value.
2173 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2174 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2175 }
2176 }
2177
2178 // Bailout case
2179 return LoadNode::Value(phase);
2180 }
2181
2182 //------------------------------Identity---------------------------------------
2183 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2184 // Also feed through the klass in Allocate(...klass...)._klass.
2185 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2186 return klass_identity_common(phase);
2187 }
2188
2189 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2190 Node* x = LoadNode::Identity(phase);
2191 if (x != this) return x;
2192
2193 // Take apart the address into an oop and and offset.
2194 // Return 'this' if we cannot.
2195 Node* adr = in(MemNode::Address);
2196 intptr_t offset = 0;
2197 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2198 if (base == NULL) return this;
2199 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2200 if (toop == NULL) return this;
2201
2202 // We can fetch the klass directly through an AllocateNode.
2203 // This works even if the klass is not constant (clone or newArray).
2204 if (offset == oopDesc::klass_offset_in_bytes()) {
2205 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2206 if (allocated_klass != NULL) {
2207 return allocated_klass;
2208 }
2209 }
2210
2211 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2212 // Simplify ak.component_mirror.array_klass to plain ak, ak an ArrayKlass.
2213 // See inline_native_Class_query for occurrences of these patterns.
2214 // Java Example: x.getClass().isAssignableFrom(y)
2215 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2216 //
2217 // This improves reflective code, often making the Class
2218 // mirror go completely dead. (Current exception: Class
2219 // mirrors may appear in debug info, but we could clean them out by
2220 // introducing a new debug info operator for Klass*.java_mirror).
2221 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2222 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2223 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2224 // We are loading a special hidden field from a Class mirror,
2225 // the field which points to its Klass or ArrayKlass metaobject.
2226 if (base->is_Load()) {
2227 Node* adr2 = base->in(MemNode::Address);
2228 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2229 if (tkls != NULL && !tkls->empty()
2230 && (tkls->klass()->is_instance_klass() ||
2231 tkls->klass()->is_array_klass())
2232 && adr2->is_AddP()
2233 ) {
2234 int mirror_field = in_bytes(Klass::java_mirror_offset());
2235 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2236 mirror_field = in_bytes(ArrayKlass::component_mirror_offset());
2237 }
2238 if (tkls->offset() == mirror_field) {
2239 return adr2->in(AddPNode::Base);
2240 }
2241 }
2242 }
2243 }
2244
2245 return this;
2246 }
2247
2248
2249 //------------------------------Value------------------------------------------
2250 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2251 const Type *t = klass_value_common(phase);
2252 if (t == Type::TOP)
2253 return t;
2254
2255 return t->make_narrowklass();
2256 }
2257
2258 //------------------------------Identity---------------------------------------
2259 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2260 // Also feed through the klass in Allocate(...klass...)._klass.
2261 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2262 Node *x = klass_identity_common(phase);
2263
2264 const Type *t = phase->type( x );
2265 if( t == Type::TOP ) return x;
2266 if( t->isa_narrowklass()) return x;
2267 assert (!t->isa_narrowoop(), "no narrow oop here");
2268
2269 return phase->transform(new (phase->C) EncodePKlassNode(x, t->make_narrowklass()));
2270 }
2271
2272 //------------------------------Value-----------------------------------------
2273 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2274 // Either input is TOP ==> the result is TOP
2275 const Type *t1 = phase->type( in(MemNode::Memory) );
2276 if( t1 == Type::TOP ) return Type::TOP;
2277 Node *adr = in(MemNode::Address);
2278 const Type *t2 = phase->type( adr );
2279 if( t2 == Type::TOP ) return Type::TOP;
2280 const TypePtr *tp = t2->is_ptr();
2281 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2282 const TypeAryPtr *tap = tp->isa_aryptr();
2283 if( !tap ) return _type;
2284 return tap->size();
2285 }
2286
2287 //-------------------------------Ideal---------------------------------------
2288 // Feed through the length in AllocateArray(...length...)._length.
2289 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2290 Node* p = MemNode::Ideal_common(phase, can_reshape);
2291 if (p) return (p == NodeSentinel) ? NULL : p;
2292
2293 // Take apart the address into an oop and and offset.
2294 // Return 'this' if we cannot.
2295 Node* adr = in(MemNode::Address);
2296 intptr_t offset = 0;
2297 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2298 if (base == NULL) return NULL;
2299 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2300 if (tary == NULL) return NULL;
2301
2302 // We can fetch the length directly through an AllocateArrayNode.
2303 // This works even if the length is not constant (clone or newArray).
2304 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2305 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2306 if (alloc != NULL) {
2307 Node* allocated_length = alloc->Ideal_length();
2308 Node* len = alloc->make_ideal_length(tary, phase);
2309 if (allocated_length != len) {
2310 // New CastII improves on this.
2311 return len;
2312 }
2313 }
2314 }
2315
2316 return NULL;
2317 }
2318
2319 //------------------------------Identity---------------------------------------
2320 // Feed through the length in AllocateArray(...length...)._length.
2321 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2322 Node* x = LoadINode::Identity(phase);
2323 if (x != this) return x;
2324
2325 // Take apart the address into an oop and and offset.
2326 // Return 'this' if we cannot.
2327 Node* adr = in(MemNode::Address);
2328 intptr_t offset = 0;
2329 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2330 if (base == NULL) return this;
2331 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2332 if (tary == NULL) return this;
2333
2334 // We can fetch the length directly through an AllocateArrayNode.
2335 // This works even if the length is not constant (clone or newArray).
2336 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2337 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2338 if (alloc != NULL) {
2339 Node* allocated_length = alloc->Ideal_length();
2340 // Do not allow make_ideal_length to allocate a CastII node.
2341 Node* len = alloc->make_ideal_length(tary, phase, false);
2342 if (allocated_length == len) {
2343 // Return allocated_length only if it would not be improved by a CastII.
2344 return allocated_length;
2345 }
2346 }
2347 }
2348
2349 return this;
2350
2351 }
2352
2353 //=============================================================================
2354 //---------------------------StoreNode::make-----------------------------------
2355 // Polymorphic factory method:
2356 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2357 assert((mo == unordered || mo == release), "unexpected");
2358 Compile* C = gvn.C;
2359 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2360 ctl != NULL, "raw memory operations should have control edge");
2361
2362 switch (bt) {
2363 case T_BOOLEAN:
2364 case T_BYTE: return new (C) StoreBNode(ctl, mem, adr, adr_type, val, mo);
2365 case T_INT: return new (C) StoreINode(ctl, mem, adr, adr_type, val, mo);
2366 case T_CHAR:
2367 case T_SHORT: return new (C) StoreCNode(ctl, mem, adr, adr_type, val, mo);
2368 case T_LONG: return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo);
2369 case T_FLOAT: return new (C) StoreFNode(ctl, mem, adr, adr_type, val, mo);
2370 case T_DOUBLE: return new (C) StoreDNode(ctl, mem, adr, adr_type, val, mo);
2371 case T_METADATA:
2372 case T_ADDRESS:
2373 case T_OBJECT:
2374 #ifdef _LP64
2375 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2376 val = gvn.transform(new (C) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2377 return new (C) StoreNNode(ctl, mem, adr, adr_type, val, mo);
2378 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2379 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2380 adr->bottom_type()->isa_rawptr())) {
2381 val = gvn.transform(new (C) EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2382 return new (C) StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2383 }
2384 #endif
2385 {
2386 return new (C) StorePNode(ctl, mem, adr, adr_type, val, mo);
2387 }
2388 }
2389 ShouldNotReachHere();
2390 return (StoreNode*)NULL;
2391 }
2392
2393 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2394 bool require_atomic = true;
2395 return new (C) StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2396 }
2397
2398
2399 //--------------------------bottom_type----------------------------------------
2400 const Type *StoreNode::bottom_type() const {
2401 return Type::MEMORY;
2402 }
2403
2404 //------------------------------hash-------------------------------------------
2405 uint StoreNode::hash() const {
2406 // unroll addition of interesting fields
2407 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2408
2409 // Since they are not commoned, do not hash them:
2410 return NO_HASH;
2411 }
2412
2413 //------------------------------Ideal------------------------------------------
2414 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2415 // When a store immediately follows a relevant allocation/initialization,
2416 // try to capture it into the initialization, or hoist it above.
2417 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2418 Node* p = MemNode::Ideal_common(phase, can_reshape);
2419 if (p) return (p == NodeSentinel) ? NULL : p;
2420
2421 Node* mem = in(MemNode::Memory);
2422 Node* address = in(MemNode::Address);
2423
2424 // Back-to-back stores to same address? Fold em up. Generally
2425 // unsafe if I have intervening uses... Also disallowed for StoreCM
2426 // since they must follow each StoreP operation. Redundant StoreCMs
2427 // are eliminated just before matching in final_graph_reshape.
2428 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2429 mem->Opcode() != Op_StoreCM) {
2430 // Looking at a dead closed cycle of memory?
2431 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2432
2433 assert(Opcode() == mem->Opcode() ||
2434 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2435 "no mismatched stores, except on raw memory");
2436
2437 if (mem->outcnt() == 1 && // check for intervening uses
2438 mem->as_Store()->memory_size() <= this->memory_size()) {
2439 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2440 // For example, 'mem' might be the final state at a conditional return.
2441 // Or, 'mem' might be used by some node which is live at the same time
2442 // 'this' is live, which might be unschedulable. So, require exactly
2443 // ONE user, the 'this' store, until such time as we clone 'mem' for
2444 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2445 if (can_reshape) { // (%%% is this an anachronism?)
2446 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2447 phase->is_IterGVN());
2448 } else {
2449 // It's OK to do this in the parser, since DU info is always accurate,
2450 // and the parser always refers to nodes via SafePointNode maps.
2451 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2452 }
2453 return this;
2454 }
2455 }
2456
2457 // Capture an unaliased, unconditional, simple store into an initializer.
2458 // Or, if it is independent of the allocation, hoist it above the allocation.
2459 if (ReduceFieldZeroing && /*can_reshape &&*/
2460 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2461 InitializeNode* init = mem->in(0)->as_Initialize();
2462 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2463 if (offset > 0) {
2464 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2465 // If the InitializeNode captured me, it made a raw copy of me,
2466 // and I need to disappear.
2467 if (moved != NULL) {
2468 // %%% hack to ensure that Ideal returns a new node:
2469 mem = MergeMemNode::make(phase->C, mem);
2470 return mem; // fold me away
2471 }
2472 }
2473 }
2474
2475 return NULL; // No further progress
2476 }
2477
2478 //------------------------------Value-----------------------------------------
2479 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2480 // Either input is TOP ==> the result is TOP
2481 const Type *t1 = phase->type( in(MemNode::Memory) );
2482 if( t1 == Type::TOP ) return Type::TOP;
2483 const Type *t2 = phase->type( in(MemNode::Address) );
2484 if( t2 == Type::TOP ) return Type::TOP;
2485 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2486 if( t3 == Type::TOP ) return Type::TOP;
2487 return Type::MEMORY;
2488 }
2489
2490 //------------------------------Identity---------------------------------------
2491 // Remove redundant stores:
2492 // Store(m, p, Load(m, p)) changes to m.
2493 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2494 Node *StoreNode::Identity( PhaseTransform *phase ) {
2495 Node* mem = in(MemNode::Memory);
2496 Node* adr = in(MemNode::Address);
2497 Node* val = in(MemNode::ValueIn);
2498
2499 // Load then Store? Then the Store is useless
2500 if (val->is_Load() &&
2501 val->in(MemNode::Address)->eqv_uncast(adr) &&
2502 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2503 val->as_Load()->store_Opcode() == Opcode()) {
2504 return mem;
2505 }
2506
2507 // Two stores in a row of the same value?
2508 if (mem->is_Store() &&
2509 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2510 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2511 mem->Opcode() == Opcode()) {
2512 return mem;
2513 }
2514
2515 // Store of zero anywhere into a freshly-allocated object?
2516 // Then the store is useless.
2517 // (It must already have been captured by the InitializeNode.)
2518 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2519 // a newly allocated object is already all-zeroes everywhere
2520 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2521 return mem;
2522 }
2523
2524 // the store may also apply to zero-bits in an earlier object
2525 Node* prev_mem = find_previous_store(phase);
2526 // Steps (a), (b): Walk past independent stores to find an exact match.
2527 if (prev_mem != NULL) {
2528 Node* prev_val = can_see_stored_value(prev_mem, phase);
2529 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2530 // prev_val and val might differ by a cast; it would be good
2531 // to keep the more informative of the two.
2532 return mem;
2533 }
2534 }
2535 }
2536
2537 return this;
2538 }
2539
2540 //------------------------------match_edge-------------------------------------
2541 // Do we Match on this edge index or not? Match only memory & value
2542 uint StoreNode::match_edge(uint idx) const {
2543 return idx == MemNode::Address || idx == MemNode::ValueIn;
2544 }
2545
2546 //------------------------------cmp--------------------------------------------
2547 // Do not common stores up together. They generally have to be split
2548 // back up anyways, so do not bother.
2549 uint StoreNode::cmp( const Node &n ) const {
2550 return (&n == this); // Always fail except on self
2551 }
2552
2553 //------------------------------Ideal_masked_input-----------------------------
2554 // Check for a useless mask before a partial-word store
2555 // (StoreB ... (AndI valIn conIa) )
2556 // If (conIa & mask == mask) this simplifies to
2557 // (StoreB ... (valIn) )
2558 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2559 Node *val = in(MemNode::ValueIn);
2560 if( val->Opcode() == Op_AndI ) {
2561 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2562 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2563 set_req(MemNode::ValueIn, val->in(1));
2564 return this;
2565 }
2566 }
2567 return NULL;
2568 }
2569
2570
2571 //------------------------------Ideal_sign_extended_input----------------------
2572 // Check for useless sign-extension before a partial-word store
2573 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2574 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2575 // (StoreB ... (valIn) )
2576 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2577 Node *val = in(MemNode::ValueIn);
2578 if( val->Opcode() == Op_RShiftI ) {
2579 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2580 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2581 Node *shl = val->in(1);
2582 if( shl->Opcode() == Op_LShiftI ) {
2583 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2584 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2585 set_req(MemNode::ValueIn, shl->in(1));
2586 return this;
2587 }
2588 }
2589 }
2590 }
2591 return NULL;
2592 }
2593
2594 //------------------------------value_never_loaded-----------------------------------
2595 // Determine whether there are any possible loads of the value stored.
2596 // For simplicity, we actually check if there are any loads from the
2597 // address stored to, not just for loads of the value stored by this node.
2598 //
2599 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2600 Node *adr = in(Address);
2601 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2602 if (adr_oop == NULL)
2603 return false;
2604 if (!adr_oop->is_known_instance_field())
2605 return false; // if not a distinct instance, there may be aliases of the address
2606 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2607 Node *use = adr->fast_out(i);
2608 int opc = use->Opcode();
2609 if (use->is_Load() || use->is_LoadStore()) {
2610 return false;
2611 }
2612 }
2613 return true;
2614 }
2615
2616 //=============================================================================
2617 //------------------------------Ideal------------------------------------------
2618 // If the store is from an AND mask that leaves the low bits untouched, then
2619 // we can skip the AND operation. If the store is from a sign-extension
2620 // (a left shift, then right shift) we can skip both.
2621 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2622 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2623 if( progress != NULL ) return progress;
2624
2625 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2626 if( progress != NULL ) return progress;
2627
2628 // Finally check the default case
2629 return StoreNode::Ideal(phase, can_reshape);
2630 }
2631
2632 //=============================================================================
2633 //------------------------------Ideal------------------------------------------
2634 // If the store is from an AND mask that leaves the low bits untouched, then
2635 // we can skip the AND operation
2636 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2637 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2638 if( progress != NULL ) return progress;
2639
2640 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2641 if( progress != NULL ) return progress;
2642
2643 // Finally check the default case
2644 return StoreNode::Ideal(phase, can_reshape);
2645 }
2646
2647 //=============================================================================
2648 //------------------------------Identity---------------------------------------
2649 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2650 // No need to card mark when storing a null ptr
2651 Node* my_store = in(MemNode::OopStore);
2652 if (my_store->is_Store()) {
2653 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2654 if( t1 == TypePtr::NULL_PTR ) {
2655 return in(MemNode::Memory);
2656 }
2657 }
2658 return this;
2659 }
2660
2661 //=============================================================================
2662 //------------------------------Ideal---------------------------------------
2663 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2664 Node* progress = StoreNode::Ideal(phase, can_reshape);
2665 if (progress != NULL) return progress;
2666
2667 Node* my_store = in(MemNode::OopStore);
2668 if (my_store->is_MergeMem()) {
2669 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2670 set_req(MemNode::OopStore, mem);
2671 return this;
2672 }
2673
2674 return NULL;
2675 }
2676
2677 //------------------------------Value-----------------------------------------
2678 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2679 // Either input is TOP ==> the result is TOP
2680 const Type *t = phase->type( in(MemNode::Memory) );
2681 if( t == Type::TOP ) return Type::TOP;
2682 t = phase->type( in(MemNode::Address) );
2683 if( t == Type::TOP ) return Type::TOP;
2684 t = phase->type( in(MemNode::ValueIn) );
2685 if( t == Type::TOP ) return Type::TOP;
2686 // If extra input is TOP ==> the result is TOP
2687 t = phase->type( in(MemNode::OopStore) );
2688 if( t == Type::TOP ) return Type::TOP;
2689
2690 return StoreNode::Value( phase );
2691 }
2692
2693
2694 //=============================================================================
2695 //----------------------------------SCMemProjNode------------------------------
2696 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2697 {
2698 return bottom_type();
2699 }
2700
2701 //=============================================================================
2702 //----------------------------------LoadStoreNode------------------------------
2703 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2704 : Node(required),
2705 _type(rt),
2706 _adr_type(at)
2707 {
2708 init_req(MemNode::Control, c );
2709 init_req(MemNode::Memory , mem);
2710 init_req(MemNode::Address, adr);
2711 init_req(MemNode::ValueIn, val);
2712 init_class_id(Class_LoadStore);
2713 }
2714
2715 uint LoadStoreNode::ideal_reg() const {
2716 return _type->ideal_reg();
2717 }
2718
2719 bool LoadStoreNode::result_not_used() const {
2720 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2721 Node *x = fast_out(i);
2722 if (x->Opcode() == Op_SCMemProj) continue;
2723 return false;
2724 }
2725 return true;
2726 }
2727
2728 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2729
2730 //=============================================================================
2731 //----------------------------------LoadStoreConditionalNode--------------------
2732 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2733 init_req(ExpectedIn, ex );
2734 }
2735
2736 //=============================================================================
2737 //-------------------------------adr_type--------------------------------------
2738 // Do we Match on this edge index or not? Do not match memory
2739 const TypePtr* ClearArrayNode::adr_type() const {
2740 Node *adr = in(3);
2741 return MemNode::calculate_adr_type(adr->bottom_type());
2742 }
2743
2744 //------------------------------match_edge-------------------------------------
2745 // Do we Match on this edge index or not? Do not match memory
2746 uint ClearArrayNode::match_edge(uint idx) const {
2747 return idx > 1;
2748 }
2749
2750 //------------------------------Identity---------------------------------------
2751 // Clearing a zero length array does nothing
2752 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2753 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2754 }
2755
2756 //------------------------------Idealize---------------------------------------
2757 // Clearing a short array is faster with stores
2758 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2759 const int unit = BytesPerLong;
2760 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2761 if (!t) return NULL;
2762 if (!t->is_con()) return NULL;
2763 intptr_t raw_count = t->get_con();
2764 intptr_t size = raw_count;
2765 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2766 // Clearing nothing uses the Identity call.
2767 // Negative clears are possible on dead ClearArrays
2768 // (see jck test stmt114.stmt11402.val).
2769 if (size <= 0 || size % unit != 0) return NULL;
2770 intptr_t count = size / unit;
2771 // Length too long; use fast hardware clear
2772 if (size > Matcher::init_array_short_size) return NULL;
2773 Node *mem = in(1);
2774 if( phase->type(mem)==Type::TOP ) return NULL;
2775 Node *adr = in(3);
2776 const Type* at = phase->type(adr);
2777 if( at==Type::TOP ) return NULL;
2778 const TypePtr* atp = at->isa_ptr();
2779 // adjust atp to be the correct array element address type
2780 if (atp == NULL) atp = TypePtr::BOTTOM;
2781 else atp = atp->add_offset(Type::OffsetBot);
2782 // Get base for derived pointer purposes
2783 if( adr->Opcode() != Op_AddP ) Unimplemented();
2784 Node *base = adr->in(1);
2785
2786 Node *zero = phase->makecon(TypeLong::ZERO);
2787 Node *off = phase->MakeConX(BytesPerLong);
2788 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2789 count--;
2790 while( count-- ) {
2791 mem = phase->transform(mem);
2792 adr = phase->transform(new (phase->C) AddPNode(base,adr,off));
2793 mem = new (phase->C) StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2794 }
2795 return mem;
2796 }
2797
2798 //----------------------------step_through----------------------------------
2799 // Return allocation input memory edge if it is different instance
2800 // or itself if it is the one we are looking for.
2801 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2802 Node* n = *np;
2803 assert(n->is_ClearArray(), "sanity");
2804 intptr_t offset;
2805 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2806 // This method is called only before Allocate nodes are expanded during
2807 // macro nodes expansion. Before that ClearArray nodes are only generated
2808 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2809 assert(alloc != NULL, "should have allocation");
2810 if (alloc->_idx == instance_id) {
2811 // Can not bypass initialization of the instance we are looking for.
2812 return false;
2813 }
2814 // Otherwise skip it.
2815 InitializeNode* init = alloc->initialization();
2816 if (init != NULL)
2817 *np = init->in(TypeFunc::Memory);
2818 else
2819 *np = alloc->in(TypeFunc::Memory);
2820 return true;
2821 }
2822
2823 //----------------------------clear_memory-------------------------------------
2824 // Generate code to initialize object storage to zero.
2825 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2826 intptr_t start_offset,
2827 Node* end_offset,
2828 PhaseGVN* phase) {
2829 Compile* C = phase->C;
2830 intptr_t offset = start_offset;
2831
2832 int unit = BytesPerLong;
2833 if ((offset % unit) != 0) {
2834 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(offset));
2835 adr = phase->transform(adr);
2836 const TypePtr* atp = TypeRawPtr::BOTTOM;
2837 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2838 mem = phase->transform(mem);
2839 offset += BytesPerInt;
2840 }
2841 assert((offset % unit) == 0, "");
2842
2843 // Initialize the remaining stuff, if any, with a ClearArray.
2844 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2845 }
2846
2847 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2848 Node* start_offset,
2849 Node* end_offset,
2850 PhaseGVN* phase) {
2851 if (start_offset == end_offset) {
2852 // nothing to do
2853 return mem;
2854 }
2855
2856 Compile* C = phase->C;
2857 int unit = BytesPerLong;
2858 Node* zbase = start_offset;
2859 Node* zend = end_offset;
2860
2861 // Scale to the unit required by the CPU:
2862 if (!Matcher::init_array_count_is_in_bytes) {
2863 Node* shift = phase->intcon(exact_log2(unit));
2864 zbase = phase->transform( new(C) URShiftXNode(zbase, shift) );
2865 zend = phase->transform( new(C) URShiftXNode(zend, shift) );
2866 }
2867
2868 // Bulk clear double-words
2869 Node* zsize = phase->transform( new(C) SubXNode(zend, zbase) );
2870 Node* adr = phase->transform( new(C) AddPNode(dest, dest, start_offset) );
2871 mem = new (C) ClearArrayNode(ctl, mem, zsize, adr);
2872 return phase->transform(mem);
2873 }
2874
2875 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2876 intptr_t start_offset,
2877 intptr_t end_offset,
2878 PhaseGVN* phase) {
2879 if (start_offset == end_offset) {
2880 // nothing to do
2881 return mem;
2882 }
2883
2884 Compile* C = phase->C;
2885 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2886 intptr_t done_offset = end_offset;
2887 if ((done_offset % BytesPerLong) != 0) {
2888 done_offset -= BytesPerInt;
2889 }
2890 if (done_offset > start_offset) {
2891 mem = clear_memory(ctl, mem, dest,
2892 start_offset, phase->MakeConX(done_offset), phase);
2893 }
2894 if (done_offset < end_offset) { // emit the final 32-bit store
2895 Node* adr = new (C) AddPNode(dest, dest, phase->MakeConX(done_offset));
2896 adr = phase->transform(adr);
2897 const TypePtr* atp = TypeRawPtr::BOTTOM;
2898 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2899 mem = phase->transform(mem);
2900 done_offset += BytesPerInt;
2901 }
2902 assert(done_offset == end_offset, "");
2903 return mem;
2904 }
2905
2906 //=============================================================================
2907 // Do not match memory edge.
2908 uint StrIntrinsicNode::match_edge(uint idx) const {
2909 return idx == 2 || idx == 3;
2910 }
2911
2912 //------------------------------Ideal------------------------------------------
2913 // Return a node which is more "ideal" than the current node. Strip out
2914 // control copies
2915 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2916 if (remove_dead_region(phase, can_reshape)) return this;
2917 // Don't bother trying to transform a dead node
2918 if (in(0) && in(0)->is_top()) return NULL;
2919
2920 if (can_reshape) {
2921 Node* mem = phase->transform(in(MemNode::Memory));
2922 // If transformed to a MergeMem, get the desired slice
2923 uint alias_idx = phase->C->get_alias_index(adr_type());
2924 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2925 if (mem != in(MemNode::Memory)) {
2926 set_req(MemNode::Memory, mem);
2927 return this;
2928 }
2929 }
2930 return NULL;
2931 }
2932
2933 //------------------------------Value------------------------------------------
2934 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2935 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2936 return bottom_type();
2937 }
2938
2939 //=============================================================================
2940 //------------------------------match_edge-------------------------------------
2941 // Do not match memory edge
2942 uint EncodeISOArrayNode::match_edge(uint idx) const {
2943 return idx == 2 || idx == 3; // EncodeISOArray src (Binary dst len)
2944 }
2945
2946 //------------------------------Ideal------------------------------------------
2947 // Return a node which is more "ideal" than the current node. Strip out
2948 // control copies
2949 Node *EncodeISOArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2950 return remove_dead_region(phase, can_reshape) ? this : NULL;
2951 }
2952
2953 //------------------------------Value------------------------------------------
2954 const Type *EncodeISOArrayNode::Value(PhaseTransform *phase) const {
2955 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2956 return bottom_type();
2957 }
2958
2959 //=============================================================================
2960 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2961 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2962 _adr_type(C->get_adr_type(alias_idx))
2963 {
2964 init_class_id(Class_MemBar);
2965 Node* top = C->top();
2966 init_req(TypeFunc::I_O,top);
2967 init_req(TypeFunc::FramePtr,top);
2968 init_req(TypeFunc::ReturnAdr,top);
2969 if (precedent != NULL)
2970 init_req(TypeFunc::Parms, precedent);
2971 }
2972
2973 //------------------------------cmp--------------------------------------------
2974 uint MemBarNode::hash() const { return NO_HASH; }
2975 uint MemBarNode::cmp( const Node &n ) const {
2976 return (&n == this); // Always fail except on self
2977 }
2978
2979 //------------------------------make-------------------------------------------
2980 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2981 switch (opcode) {
2982 case Op_MemBarAcquire: return new(C) MemBarAcquireNode(C, atp, pn);
2983 case Op_LoadFence: return new(C) LoadFenceNode(C, atp, pn);
2984 case Op_MemBarRelease: return new(C) MemBarReleaseNode(C, atp, pn);
2985 case Op_StoreFence: return new(C) StoreFenceNode(C, atp, pn);
2986 case Op_MemBarAcquireLock: return new(C) MemBarAcquireLockNode(C, atp, pn);
2987 case Op_MemBarReleaseLock: return new(C) MemBarReleaseLockNode(C, atp, pn);
2988 case Op_MemBarVolatile: return new(C) MemBarVolatileNode(C, atp, pn);
2989 case Op_MemBarCPUOrder: return new(C) MemBarCPUOrderNode(C, atp, pn);
2990 case Op_Initialize: return new(C) InitializeNode(C, atp, pn);
2991 case Op_MemBarStoreStore: return new(C) MemBarStoreStoreNode(C, atp, pn);
2992 default: ShouldNotReachHere(); return NULL;
2993 }
2994 }
2995
2996 //------------------------------Ideal------------------------------------------
2997 // Return a node which is more "ideal" than the current node. Strip out
2998 // control copies
2999 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3000 if (remove_dead_region(phase, can_reshape)) return this;
3001 // Don't bother trying to transform a dead node
3002 if (in(0) && in(0)->is_top()) {
3003 return NULL;
3004 }
3005
3006 // Eliminate volatile MemBars for scalar replaced objects.
3007 if (can_reshape && req() == (Precedent+1)) {
3008 bool eliminate = false;
3009 int opc = Opcode();
3010 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3011 // Volatile field loads and stores.
3012 Node* my_mem = in(MemBarNode::Precedent);
3013 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3014 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3015 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3016 // replace this Precedent (decodeN) with the Load instead.
3017 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3018 Node* load_node = my_mem->in(1);
3019 set_req(MemBarNode::Precedent, load_node);
3020 phase->is_IterGVN()->_worklist.push(my_mem);
3021 my_mem = load_node;
3022 } else {
3023 assert(my_mem->unique_out() == this, "sanity");
3024 del_req(Precedent);
3025 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3026 my_mem = NULL;
3027 }
3028 }
3029 if (my_mem != NULL && my_mem->is_Mem()) {
3030 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3031 // Check for scalar replaced object reference.
3032 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3033 t_oop->offset() != Type::OffsetBot &&
3034 t_oop->offset() != Type::OffsetTop) {
3035 eliminate = true;
3036 }
3037 }
3038 } else if (opc == Op_MemBarRelease) {
3039 // Final field stores.
3040 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3041 if ((alloc != NULL) && alloc->is_Allocate() &&
3042 alloc->as_Allocate()->_is_non_escaping) {
3043 // The allocated object does not escape.
3044 eliminate = true;
3045 }
3046 }
3047 if (eliminate) {
3048 // Replace MemBar projections by its inputs.
3049 PhaseIterGVN* igvn = phase->is_IterGVN();
3050 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3051 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3052 // Must return either the original node (now dead) or a new node
3053 // (Do not return a top here, since that would break the uniqueness of top.)
3054 return new (phase->C) ConINode(TypeInt::ZERO);
3055 }
3056 }
3057 return NULL;
3058 }
3059
3060 //------------------------------Value------------------------------------------
3061 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
3062 if( !in(0) ) return Type::TOP;
3063 if( phase->type(in(0)) == Type::TOP )
3064 return Type::TOP;
3065 return TypeTuple::MEMBAR;
3066 }
3067
3068 //------------------------------match------------------------------------------
3069 // Construct projections for memory.
3070 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3071 switch (proj->_con) {
3072 case TypeFunc::Control:
3073 case TypeFunc::Memory:
3074 return new (m->C) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3075 }
3076 ShouldNotReachHere();
3077 return NULL;
3078 }
3079
3080 //===========================InitializeNode====================================
3081 // SUMMARY:
3082 // This node acts as a memory barrier on raw memory, after some raw stores.
3083 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3084 // The Initialize can 'capture' suitably constrained stores as raw inits.
3085 // It can coalesce related raw stores into larger units (called 'tiles').
3086 // It can avoid zeroing new storage for memory units which have raw inits.
3087 // At macro-expansion, it is marked 'complete', and does not optimize further.
3088 //
3089 // EXAMPLE:
3090 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3091 // ctl = incoming control; mem* = incoming memory
3092 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3093 // First allocate uninitialized memory and fill in the header:
3094 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3095 // ctl := alloc.Control; mem* := alloc.Memory*
3096 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3097 // Then initialize to zero the non-header parts of the raw memory block:
3098 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3099 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3100 // After the initialize node executes, the object is ready for service:
3101 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3102 // Suppose its body is immediately initialized as {1,2}:
3103 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3104 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3105 // mem.SLICE(#short[*]) := store2
3106 //
3107 // DETAILS:
3108 // An InitializeNode collects and isolates object initialization after
3109 // an AllocateNode and before the next possible safepoint. As a
3110 // memory barrier (MemBarNode), it keeps critical stores from drifting
3111 // down past any safepoint or any publication of the allocation.
3112 // Before this barrier, a newly-allocated object may have uninitialized bits.
3113 // After this barrier, it may be treated as a real oop, and GC is allowed.
3114 //
3115 // The semantics of the InitializeNode include an implicit zeroing of
3116 // the new object from object header to the end of the object.
3117 // (The object header and end are determined by the AllocateNode.)
3118 //
3119 // Certain stores may be added as direct inputs to the InitializeNode.
3120 // These stores must update raw memory, and they must be to addresses
3121 // derived from the raw address produced by AllocateNode, and with
3122 // a constant offset. They must be ordered by increasing offset.
3123 // The first one is at in(RawStores), the last at in(req()-1).
3124 // Unlike most memory operations, they are not linked in a chain,
3125 // but are displayed in parallel as users of the rawmem output of
3126 // the allocation.
3127 //
3128 // (See comments in InitializeNode::capture_store, which continue
3129 // the example given above.)
3130 //
3131 // When the associated Allocate is macro-expanded, the InitializeNode
3132 // may be rewritten to optimize collected stores. A ClearArrayNode
3133 // may also be created at that point to represent any required zeroing.
3134 // The InitializeNode is then marked 'complete', prohibiting further
3135 // capturing of nearby memory operations.
3136 //
3137 // During macro-expansion, all captured initializations which store
3138 // constant values of 32 bits or smaller are coalesced (if advantageous)
3139 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3140 // initialized in fewer memory operations. Memory words which are
3141 // covered by neither tiles nor non-constant stores are pre-zeroed
3142 // by explicit stores of zero. (The code shape happens to do all
3143 // zeroing first, then all other stores, with both sequences occurring
3144 // in order of ascending offsets.)
3145 //
3146 // Alternatively, code may be inserted between an AllocateNode and its
3147 // InitializeNode, to perform arbitrary initialization of the new object.
3148 // E.g., the object copying intrinsics insert complex data transfers here.
3149 // The initialization must then be marked as 'complete' disable the
3150 // built-in zeroing semantics and the collection of initializing stores.
3151 //
3152 // While an InitializeNode is incomplete, reads from the memory state
3153 // produced by it are optimizable if they match the control edge and
3154 // new oop address associated with the allocation/initialization.
3155 // They return a stored value (if the offset matches) or else zero.
3156 // A write to the memory state, if it matches control and address,
3157 // and if it is to a constant offset, may be 'captured' by the
3158 // InitializeNode. It is cloned as a raw memory operation and rewired
3159 // inside the initialization, to the raw oop produced by the allocation.
3160 // Operations on addresses which are provably distinct (e.g., to
3161 // other AllocateNodes) are allowed to bypass the initialization.
3162 //
3163 // The effect of all this is to consolidate object initialization
3164 // (both arrays and non-arrays, both piecewise and bulk) into a
3165 // single location, where it can be optimized as a unit.
3166 //
3167 // Only stores with an offset less than TrackedInitializationLimit words
3168 // will be considered for capture by an InitializeNode. This puts a
3169 // reasonable limit on the complexity of optimized initializations.
3170
3171 //---------------------------InitializeNode------------------------------------
3172 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3173 : _is_complete(Incomplete), _does_not_escape(false),
3174 MemBarNode(C, adr_type, rawoop)
3175 {
3176 init_class_id(Class_Initialize);
3177
3178 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3179 assert(in(RawAddress) == rawoop, "proper init");
3180 // Note: allocation() can be NULL, for secondary initialization barriers
3181 }
3182
3183 // Since this node is not matched, it will be processed by the
3184 // register allocator. Declare that there are no constraints
3185 // on the allocation of the RawAddress edge.
3186 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3187 // This edge should be set to top, by the set_complete. But be conservative.
3188 if (idx == InitializeNode::RawAddress)
3189 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3190 return RegMask::Empty;
3191 }
3192
3193 Node* InitializeNode::memory(uint alias_idx) {
3194 Node* mem = in(Memory);
3195 if (mem->is_MergeMem()) {
3196 return mem->as_MergeMem()->memory_at(alias_idx);
3197 } else {
3198 // incoming raw memory is not split
3199 return mem;
3200 }
3201 }
3202
3203 bool InitializeNode::is_non_zero() {
3204 if (is_complete()) return false;
3205 remove_extra_zeroes();
3206 return (req() > RawStores);
3207 }
3208
3209 void InitializeNode::set_complete(PhaseGVN* phase) {
3210 assert(!is_complete(), "caller responsibility");
3211 _is_complete = Complete;
3212
3213 // After this node is complete, it contains a bunch of
3214 // raw-memory initializations. There is no need for
3215 // it to have anything to do with non-raw memory effects.
3216 // Therefore, tell all non-raw users to re-optimize themselves,
3217 // after skipping the memory effects of this initialization.
3218 PhaseIterGVN* igvn = phase->is_IterGVN();
3219 if (igvn) igvn->add_users_to_worklist(this);
3220 }
3221
3222 // convenience function
3223 // return false if the init contains any stores already
3224 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3225 InitializeNode* init = initialization();
3226 if (init == NULL || init->is_complete()) return false;
3227 init->remove_extra_zeroes();
3228 // for now, if this allocation has already collected any inits, bail:
3229 if (init->is_non_zero()) return false;
3230 init->set_complete(phase);
3231 return true;
3232 }
3233
3234 void InitializeNode::remove_extra_zeroes() {
3235 if (req() == RawStores) return;
3236 Node* zmem = zero_memory();
3237 uint fill = RawStores;
3238 for (uint i = fill; i < req(); i++) {
3239 Node* n = in(i);
3240 if (n->is_top() || n == zmem) continue; // skip
3241 if (fill < i) set_req(fill, n); // compact
3242 ++fill;
3243 }
3244 // delete any empty spaces created:
3245 while (fill < req()) {
3246 del_req(fill);
3247 }
3248 }
3249
3250 // Helper for remembering which stores go with which offsets.
3251 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3252 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3253 intptr_t offset = -1;
3254 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3255 phase, offset);
3256 if (base == NULL) return -1; // something is dead,
3257 if (offset < 0) return -1; // dead, dead
3258 return offset;
3259 }
3260
3261 // Helper for proving that an initialization expression is
3262 // "simple enough" to be folded into an object initialization.
3263 // Attempts to prove that a store's initial value 'n' can be captured
3264 // within the initialization without creating a vicious cycle, such as:
3265 // { Foo p = new Foo(); p.next = p; }
3266 // True for constants and parameters and small combinations thereof.
3267 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3268 if (n == NULL) return true; // (can this really happen?)
3269 if (n->is_Proj()) n = n->in(0);
3270 if (n == this) return false; // found a cycle
3271 if (n->is_Con()) return true;
3272 if (n->is_Start()) return true; // params, etc., are OK
3273 if (n->is_Root()) return true; // even better
3274
3275 Node* ctl = n->in(0);
3276 if (ctl != NULL && !ctl->is_top()) {
3277 if (ctl->is_Proj()) ctl = ctl->in(0);
3278 if (ctl == this) return false;
3279
3280 // If we already know that the enclosing memory op is pinned right after
3281 // the init, then any control flow that the store has picked up
3282 // must have preceded the init, or else be equal to the init.
3283 // Even after loop optimizations (which might change control edges)
3284 // a store is never pinned *before* the availability of its inputs.
3285 if (!MemNode::all_controls_dominate(n, this))
3286 return false; // failed to prove a good control
3287 }
3288
3289 // Check data edges for possible dependencies on 'this'.
3290 if ((count += 1) > 20) return false; // complexity limit
3291 for (uint i = 1; i < n->req(); i++) {
3292 Node* m = n->in(i);
3293 if (m == NULL || m == n || m->is_top()) continue;
3294 uint first_i = n->find_edge(m);
3295 if (i != first_i) continue; // process duplicate edge just once
3296 if (!detect_init_independence(m, count)) {
3297 return false;
3298 }
3299 }
3300
3301 return true;
3302 }
3303
3304 // Here are all the checks a Store must pass before it can be moved into
3305 // an initialization. Returns zero if a check fails.
3306 // On success, returns the (constant) offset to which the store applies,
3307 // within the initialized memory.
3308 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3309 const int FAIL = 0;
3310 if (st->req() != MemNode::ValueIn + 1)
3311 return FAIL; // an inscrutable StoreNode (card mark?)
3312 Node* ctl = st->in(MemNode::Control);
3313 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3314 return FAIL; // must be unconditional after the initialization
3315 Node* mem = st->in(MemNode::Memory);
3316 if (!(mem->is_Proj() && mem->in(0) == this))
3317 return FAIL; // must not be preceded by other stores
3318 Node* adr = st->in(MemNode::Address);
3319 intptr_t offset;
3320 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3321 if (alloc == NULL)
3322 return FAIL; // inscrutable address
3323 if (alloc != allocation())
3324 return FAIL; // wrong allocation! (store needs to float up)
3325 Node* val = st->in(MemNode::ValueIn);
3326 int complexity_count = 0;
3327 if (!detect_init_independence(val, complexity_count))
3328 return FAIL; // stored value must be 'simple enough'
3329
3330 // The Store can be captured only if nothing after the allocation
3331 // and before the Store is using the memory location that the store
3332 // overwrites.
3333 bool failed = false;
3334 // If is_complete_with_arraycopy() is true the shape of the graph is
3335 // well defined and is safe so no need for extra checks.
3336 if (!is_complete_with_arraycopy()) {
3337 // We are going to look at each use of the memory state following
3338 // the allocation to make sure nothing reads the memory that the
3339 // Store writes.
3340 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3341 int alias_idx = phase->C->get_alias_index(t_adr);
3342 ResourceMark rm;
3343 Unique_Node_List mems;
3344 mems.push(mem);
3345 Node* unique_merge = NULL;
3346 for (uint next = 0; next < mems.size(); ++next) {
3347 Node *m = mems.at(next);
3348 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3349 Node *n = m->fast_out(j);
3350 if (n->outcnt() == 0) {
3351 continue;
3352 }
3353 if (n == st) {
3354 continue;
3355 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3356 // If the control of this use is different from the control
3357 // of the Store which is right after the InitializeNode then
3358 // this node cannot be between the InitializeNode and the
3359 // Store.
3360 continue;
3361 } else if (n->is_MergeMem()) {
3362 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3363 // We can hit a MergeMemNode (that will likely go away
3364 // later) that is a direct use of the memory state
3365 // following the InitializeNode on the same slice as the
3366 // store node that we'd like to capture. We need to check
3367 // the uses of the MergeMemNode.
3368 mems.push(n);
3369 }
3370 } else if (n->is_Mem()) {
3371 Node* other_adr = n->in(MemNode::Address);
3372 if (other_adr == adr) {
3373 failed = true;
3374 break;
3375 } else {
3376 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3377 if (other_t_adr != NULL) {
3378 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3379 if (other_alias_idx == alias_idx) {
3380 // A load from the same memory slice as the store right
3381 // after the InitializeNode. We check the control of the
3382 // object/array that is loaded from. If it's the same as
3383 // the store control then we cannot capture the store.
3384 assert(!n->is_Store(), "2 stores to same slice on same control?");
3385 Node* base = other_adr;
3386 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3387 base = base->in(AddPNode::Base);
3388 if (base != NULL) {
3389 base = base->uncast();
3390 if (base->is_Proj() && base->in(0) == alloc) {
3391 failed = true;
3392 break;
3393 }
3394 }
3395 }
3396 }
3397 }
3398 } else {
3399 failed = true;
3400 break;
3401 }
3402 }
3403 }
3404 }
3405 if (failed) {
3406 if (!can_reshape) {
3407 // We decided we couldn't capture the store during parsing. We
3408 // should try again during the next IGVN once the graph is
3409 // cleaner.
3410 phase->C->record_for_igvn(st);
3411 }
3412 return FAIL;
3413 }
3414
3415 return offset; // success
3416 }
3417
3418 // Find the captured store in(i) which corresponds to the range
3419 // [start..start+size) in the initialized object.
3420 // If there is one, return its index i. If there isn't, return the
3421 // negative of the index where it should be inserted.
3422 // Return 0 if the queried range overlaps an initialization boundary
3423 // or if dead code is encountered.
3424 // If size_in_bytes is zero, do not bother with overlap checks.
3425 int InitializeNode::captured_store_insertion_point(intptr_t start,
3426 int size_in_bytes,
3427 PhaseTransform* phase) {
3428 const int FAIL = 0, MAX_STORE = BytesPerLong;
3429
3430 if (is_complete())
3431 return FAIL; // arraycopy got here first; punt
3432
3433 assert(allocation() != NULL, "must be present");
3434
3435 // no negatives, no header fields:
3436 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3437
3438 // after a certain size, we bail out on tracking all the stores:
3439 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3440 if (start >= ti_limit) return FAIL;
3441
3442 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3443 if (i >= limit) return -(int)i; // not found; here is where to put it
3444
3445 Node* st = in(i);
3446 intptr_t st_off = get_store_offset(st, phase);
3447 if (st_off < 0) {
3448 if (st != zero_memory()) {
3449 return FAIL; // bail out if there is dead garbage
3450 }
3451 } else if (st_off > start) {
3452 // ...we are done, since stores are ordered
3453 if (st_off < start + size_in_bytes) {
3454 return FAIL; // the next store overlaps
3455 }
3456 return -(int)i; // not found; here is where to put it
3457 } else if (st_off < start) {
3458 if (size_in_bytes != 0 &&
3459 start < st_off + MAX_STORE &&
3460 start < st_off + st->as_Store()->memory_size()) {
3461 return FAIL; // the previous store overlaps
3462 }
3463 } else {
3464 if (size_in_bytes != 0 &&
3465 st->as_Store()->memory_size() != size_in_bytes) {
3466 return FAIL; // mismatched store size
3467 }
3468 return i;
3469 }
3470
3471 ++i;
3472 }
3473 }
3474
3475 // Look for a captured store which initializes at the offset 'start'
3476 // with the given size. If there is no such store, and no other
3477 // initialization interferes, then return zero_memory (the memory
3478 // projection of the AllocateNode).
3479 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3480 PhaseTransform* phase) {
3481 assert(stores_are_sane(phase), "");
3482 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3483 if (i == 0) {
3484 return NULL; // something is dead
3485 } else if (i < 0) {
3486 return zero_memory(); // just primordial zero bits here
3487 } else {
3488 Node* st = in(i); // here is the store at this position
3489 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3490 return st;
3491 }
3492 }
3493
3494 // Create, as a raw pointer, an address within my new object at 'offset'.
3495 Node* InitializeNode::make_raw_address(intptr_t offset,
3496 PhaseTransform* phase) {
3497 Node* addr = in(RawAddress);
3498 if (offset != 0) {
3499 Compile* C = phase->C;
3500 addr = phase->transform( new (C) AddPNode(C->top(), addr,
3501 phase->MakeConX(offset)) );
3502 }
3503 return addr;
3504 }
3505
3506 // Clone the given store, converting it into a raw store
3507 // initializing a field or element of my new object.
3508 // Caller is responsible for retiring the original store,
3509 // with subsume_node or the like.
3510 //
3511 // From the example above InitializeNode::InitializeNode,
3512 // here are the old stores to be captured:
3513 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3514 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3515 //
3516 // Here is the changed code; note the extra edges on init:
3517 // alloc = (Allocate ...)
3518 // rawoop = alloc.RawAddress
3519 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3520 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3521 // init = (Initialize alloc.Control alloc.Memory rawoop
3522 // rawstore1 rawstore2)
3523 //
3524 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3525 PhaseTransform* phase, bool can_reshape) {
3526 assert(stores_are_sane(phase), "");
3527
3528 if (start < 0) return NULL;
3529 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3530
3531 Compile* C = phase->C;
3532 int size_in_bytes = st->memory_size();
3533 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3534 if (i == 0) return NULL; // bail out
3535 Node* prev_mem = NULL; // raw memory for the captured store
3536 if (i > 0) {
3537 prev_mem = in(i); // there is a pre-existing store under this one
3538 set_req(i, C->top()); // temporarily disconnect it
3539 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3540 } else {
3541 i = -i; // no pre-existing store
3542 prev_mem = zero_memory(); // a slice of the newly allocated object
3543 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3544 set_req(--i, C->top()); // reuse this edge; it has been folded away
3545 else
3546 ins_req(i, C->top()); // build a new edge
3547 }
3548 Node* new_st = st->clone();
3549 new_st->set_req(MemNode::Control, in(Control));
3550 new_st->set_req(MemNode::Memory, prev_mem);
3551 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3552 new_st = phase->transform(new_st);
3553
3554 // At this point, new_st might have swallowed a pre-existing store
3555 // at the same offset, or perhaps new_st might have disappeared,
3556 // if it redundantly stored the same value (or zero to fresh memory).
3557
3558 // In any case, wire it in:
3559 set_req(i, new_st);
3560
3561 // The caller may now kill the old guy.
3562 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3563 assert(check_st == new_st || check_st == NULL, "must be findable");
3564 assert(!is_complete(), "");
3565 return new_st;
3566 }
3567
3568 static bool store_constant(jlong* tiles, int num_tiles,
3569 intptr_t st_off, int st_size,
3570 jlong con) {
3571 if ((st_off & (st_size-1)) != 0)
3572 return false; // strange store offset (assume size==2**N)
3573 address addr = (address)tiles + st_off;
3574 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3575 switch (st_size) {
3576 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3577 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3578 case sizeof(jint): *(jint*) addr = (jint) con; break;
3579 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3580 default: return false; // strange store size (detect size!=2**N here)
3581 }
3582 return true; // return success to caller
3583 }
3584
3585 // Coalesce subword constants into int constants and possibly
3586 // into long constants. The goal, if the CPU permits,
3587 // is to initialize the object with a small number of 64-bit tiles.
3588 // Also, convert floating-point constants to bit patterns.
3589 // Non-constants are not relevant to this pass.
3590 //
3591 // In terms of the running example on InitializeNode::InitializeNode
3592 // and InitializeNode::capture_store, here is the transformation
3593 // of rawstore1 and rawstore2 into rawstore12:
3594 // alloc = (Allocate ...)
3595 // rawoop = alloc.RawAddress
3596 // tile12 = 0x00010002
3597 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3598 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3599 //
3600 void
3601 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3602 Node* size_in_bytes,
3603 PhaseGVN* phase) {
3604 Compile* C = phase->C;
3605
3606 assert(stores_are_sane(phase), "");
3607 // Note: After this pass, they are not completely sane,
3608 // since there may be some overlaps.
3609
3610 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3611
3612 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3613 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3614 size_limit = MIN2(size_limit, ti_limit);
3615 size_limit = align_size_up(size_limit, BytesPerLong);
3616 int num_tiles = size_limit / BytesPerLong;
3617
3618 // allocate space for the tile map:
3619 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3620 jlong tiles_buf[small_len];
3621 Node* nodes_buf[small_len];
3622 jlong inits_buf[small_len];
3623 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3624 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3625 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3626 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3627 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3628 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3629 // tiles: exact bitwise model of all primitive constants
3630 // nodes: last constant-storing node subsumed into the tiles model
3631 // inits: which bytes (in each tile) are touched by any initializations
3632
3633 //// Pass A: Fill in the tile model with any relevant stores.
3634
3635 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3636 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3637 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3638 Node* zmem = zero_memory(); // initially zero memory state
3639 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3640 Node* st = in(i);
3641 intptr_t st_off = get_store_offset(st, phase);
3642
3643 // Figure out the store's offset and constant value:
3644 if (st_off < header_size) continue; //skip (ignore header)
3645 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3646 int st_size = st->as_Store()->memory_size();
3647 if (st_off + st_size > size_limit) break;
3648
3649 // Record which bytes are touched, whether by constant or not.
3650 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3651 continue; // skip (strange store size)
3652
3653 const Type* val = phase->type(st->in(MemNode::ValueIn));
3654 if (!val->singleton()) continue; //skip (non-con store)
3655 BasicType type = val->basic_type();
3656
3657 jlong con = 0;
3658 switch (type) {
3659 case T_INT: con = val->is_int()->get_con(); break;
3660 case T_LONG: con = val->is_long()->get_con(); break;
3661 case T_FLOAT: con = jint_cast(val->getf()); break;
3662 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3663 default: continue; //skip (odd store type)
3664 }
3665
3666 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3667 st->Opcode() == Op_StoreL) {
3668 continue; // This StoreL is already optimal.
3669 }
3670
3671 // Store down the constant.
3672 store_constant(tiles, num_tiles, st_off, st_size, con);
3673
3674 intptr_t j = st_off >> LogBytesPerLong;
3675
3676 if (type == T_INT && st_size == BytesPerInt
3677 && (st_off & BytesPerInt) == BytesPerInt) {
3678 jlong lcon = tiles[j];
3679 if (!Matcher::isSimpleConstant64(lcon) &&
3680 st->Opcode() == Op_StoreI) {
3681 // This StoreI is already optimal by itself.
3682 jint* intcon = (jint*) &tiles[j];
3683 intcon[1] = 0; // undo the store_constant()
3684
3685 // If the previous store is also optimal by itself, back up and
3686 // undo the action of the previous loop iteration... if we can.
3687 // But if we can't, just let the previous half take care of itself.
3688 st = nodes[j];
3689 st_off -= BytesPerInt;
3690 con = intcon[0];
3691 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3692 assert(st_off >= header_size, "still ignoring header");
3693 assert(get_store_offset(st, phase) == st_off, "must be");
3694 assert(in(i-1) == zmem, "must be");
3695 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3696 assert(con == tcon->is_int()->get_con(), "must be");
3697 // Undo the effects of the previous loop trip, which swallowed st:
3698 intcon[0] = 0; // undo store_constant()
3699 set_req(i-1, st); // undo set_req(i, zmem)
3700 nodes[j] = NULL; // undo nodes[j] = st
3701 --old_subword; // undo ++old_subword
3702 }
3703 continue; // This StoreI is already optimal.
3704 }
3705 }
3706
3707 // This store is not needed.
3708 set_req(i, zmem);
3709 nodes[j] = st; // record for the moment
3710 if (st_size < BytesPerLong) // something has changed
3711 ++old_subword; // includes int/float, but who's counting...
3712 else ++old_long;
3713 }
3714
3715 if ((old_subword + old_long) == 0)
3716 return; // nothing more to do
3717
3718 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3719 // Be sure to insert them before overlapping non-constant stores.
3720 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3721 for (int j = 0; j < num_tiles; j++) {
3722 jlong con = tiles[j];
3723 jlong init = inits[j];
3724 if (con == 0) continue;
3725 jint con0, con1; // split the constant, address-wise
3726 jint init0, init1; // split the init map, address-wise
3727 { union { jlong con; jint intcon[2]; } u;
3728 u.con = con;
3729 con0 = u.intcon[0];
3730 con1 = u.intcon[1];
3731 u.con = init;
3732 init0 = u.intcon[0];
3733 init1 = u.intcon[1];
3734 }
3735
3736 Node* old = nodes[j];
3737 assert(old != NULL, "need the prior store");
3738 intptr_t offset = (j * BytesPerLong);
3739
3740 bool split = !Matcher::isSimpleConstant64(con);
3741
3742 if (offset < header_size) {
3743 assert(offset + BytesPerInt >= header_size, "second int counts");
3744 assert(*(jint*)&tiles[j] == 0, "junk in header");
3745 split = true; // only the second word counts
3746 // Example: int a[] = { 42 ... }
3747 } else if (con0 == 0 && init0 == -1) {
3748 split = true; // first word is covered by full inits
3749 // Example: int a[] = { ... foo(), 42 ... }
3750 } else if (con1 == 0 && init1 == -1) {
3751 split = true; // second word is covered by full inits
3752 // Example: int a[] = { ... 42, foo() ... }
3753 }
3754
3755 // Here's a case where init0 is neither 0 nor -1:
3756 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3757 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3758 // In this case the tile is not split; it is (jlong)42.
3759 // The big tile is stored down, and then the foo() value is inserted.
3760 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3761
3762 Node* ctl = old->in(MemNode::Control);
3763 Node* adr = make_raw_address(offset, phase);
3764 const TypePtr* atp = TypeRawPtr::BOTTOM;
3765
3766 // One or two coalesced stores to plop down.
3767 Node* st[2];
3768 intptr_t off[2];
3769 int nst = 0;
3770 if (!split) {
3771 ++new_long;
3772 off[nst] = offset;
3773 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3774 phase->longcon(con), T_LONG, MemNode::unordered);
3775 } else {
3776 // Omit either if it is a zero.
3777 if (con0 != 0) {
3778 ++new_int;
3779 off[nst] = offset;
3780 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3781 phase->intcon(con0), T_INT, MemNode::unordered);
3782 }
3783 if (con1 != 0) {
3784 ++new_int;
3785 offset += BytesPerInt;
3786 adr = make_raw_address(offset, phase);
3787 off[nst] = offset;
3788 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3789 phase->intcon(con1), T_INT, MemNode::unordered);
3790 }
3791 }
3792
3793 // Insert second store first, then the first before the second.
3794 // Insert each one just before any overlapping non-constant stores.
3795 while (nst > 0) {
3796 Node* st1 = st[--nst];
3797 C->copy_node_notes_to(st1, old);
3798 st1 = phase->transform(st1);
3799 offset = off[nst];
3800 assert(offset >= header_size, "do not smash header");
3801 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3802 guarantee(ins_idx != 0, "must re-insert constant store");
3803 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3804 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3805 set_req(--ins_idx, st1);
3806 else
3807 ins_req(ins_idx, st1);
3808 }
3809 }
3810
3811 if (PrintCompilation && WizardMode)
3812 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3813 old_subword, old_long, new_int, new_long);
3814 if (C->log() != NULL)
3815 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3816 old_subword, old_long, new_int, new_long);
3817
3818 // Clean up any remaining occurrences of zmem:
3819 remove_extra_zeroes();
3820 }
3821
3822 // Explore forward from in(start) to find the first fully initialized
3823 // word, and return its offset. Skip groups of subword stores which
3824 // together initialize full words. If in(start) is itself part of a
3825 // fully initialized word, return the offset of in(start). If there
3826 // are no following full-word stores, or if something is fishy, return
3827 // a negative value.
3828 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3829 int int_map = 0;
3830 intptr_t int_map_off = 0;
3831 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3832
3833 for (uint i = start, limit = req(); i < limit; i++) {
3834 Node* st = in(i);
3835
3836 intptr_t st_off = get_store_offset(st, phase);
3837 if (st_off < 0) break; // return conservative answer
3838
3839 int st_size = st->as_Store()->memory_size();
3840 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3841 return st_off; // we found a complete word init
3842 }
3843
3844 // update the map:
3845
3846 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3847 if (this_int_off != int_map_off) {
3848 // reset the map:
3849 int_map = 0;
3850 int_map_off = this_int_off;
3851 }
3852
3853 int subword_off = st_off - this_int_off;
3854 int_map |= right_n_bits(st_size) << subword_off;
3855 if ((int_map & FULL_MAP) == FULL_MAP) {
3856 return this_int_off; // we found a complete word init
3857 }
3858
3859 // Did this store hit or cross the word boundary?
3860 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3861 if (next_int_off == this_int_off + BytesPerInt) {
3862 // We passed the current int, without fully initializing it.
3863 int_map_off = next_int_off;
3864 int_map >>= BytesPerInt;
3865 } else if (next_int_off > this_int_off + BytesPerInt) {
3866 // We passed the current and next int.
3867 return this_int_off + BytesPerInt;
3868 }
3869 }
3870
3871 return -1;
3872 }
3873
3874
3875 // Called when the associated AllocateNode is expanded into CFG.
3876 // At this point, we may perform additional optimizations.
3877 // Linearize the stores by ascending offset, to make memory
3878 // activity as coherent as possible.
3879 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3880 intptr_t header_size,
3881 Node* size_in_bytes,
3882 PhaseGVN* phase) {
3883 assert(!is_complete(), "not already complete");
3884 assert(stores_are_sane(phase), "");
3885 assert(allocation() != NULL, "must be present");
3886
3887 remove_extra_zeroes();
3888
3889 if (ReduceFieldZeroing || ReduceBulkZeroing)
3890 // reduce instruction count for common initialization patterns
3891 coalesce_subword_stores(header_size, size_in_bytes, phase);
3892
3893 Node* zmem = zero_memory(); // initially zero memory state
3894 Node* inits = zmem; // accumulating a linearized chain of inits
3895 #ifdef ASSERT
3896 intptr_t first_offset = allocation()->minimum_header_size();
3897 intptr_t last_init_off = first_offset; // previous init offset
3898 intptr_t last_init_end = first_offset; // previous init offset+size
3899 intptr_t last_tile_end = first_offset; // previous tile offset+size
3900 #endif
3901 intptr_t zeroes_done = header_size;
3902
3903 bool do_zeroing = true; // we might give up if inits are very sparse
3904 int big_init_gaps = 0; // how many large gaps have we seen?
3905
3906 if (ZeroTLAB) do_zeroing = false;
3907 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3908
3909 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3910 Node* st = in(i);
3911 intptr_t st_off = get_store_offset(st, phase);
3912 if (st_off < 0)
3913 break; // unknown junk in the inits
3914 if (st->in(MemNode::Memory) != zmem)
3915 break; // complicated store chains somehow in list
3916
3917 int st_size = st->as_Store()->memory_size();
3918 intptr_t next_init_off = st_off + st_size;
3919
3920 if (do_zeroing && zeroes_done < next_init_off) {
3921 // See if this store needs a zero before it or under it.
3922 intptr_t zeroes_needed = st_off;
3923
3924 if (st_size < BytesPerInt) {
3925 // Look for subword stores which only partially initialize words.
3926 // If we find some, we must lay down some word-level zeroes first,
3927 // underneath the subword stores.
3928 //
3929 // Examples:
3930 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3931 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3932 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3933 //
3934 // Note: coalesce_subword_stores may have already done this,
3935 // if it was prompted by constant non-zero subword initializers.
3936 // But this case can still arise with non-constant stores.
3937
3938 intptr_t next_full_store = find_next_fullword_store(i, phase);
3939
3940 // In the examples above:
3941 // in(i) p q r s x y z
3942 // st_off 12 13 14 15 12 13 14
3943 // st_size 1 1 1 1 1 1 1
3944 // next_full_s. 12 16 16 16 16 16 16
3945 // z's_done 12 16 16 16 12 16 12
3946 // z's_needed 12 16 16 16 16 16 16
3947 // zsize 0 0 0 0 4 0 4
3948 if (next_full_store < 0) {
3949 // Conservative tack: Zero to end of current word.
3950 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3951 } else {
3952 // Zero to beginning of next fully initialized word.
3953 // Or, don't zero at all, if we are already in that word.
3954 assert(next_full_store >= zeroes_needed, "must go forward");
3955 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3956 zeroes_needed = next_full_store;
3957 }
3958 }
3959
3960 if (zeroes_needed > zeroes_done) {
3961 intptr_t zsize = zeroes_needed - zeroes_done;
3962 // Do some incremental zeroing on rawmem, in parallel with inits.
3963 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3964 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3965 zeroes_done, zeroes_needed,
3966 phase);
3967 zeroes_done = zeroes_needed;
3968 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3969 do_zeroing = false; // leave the hole, next time
3970 }
3971 }
3972
3973 // Collect the store and move on:
3974 st->set_req(MemNode::Memory, inits);
3975 inits = st; // put it on the linearized chain
3976 set_req(i, zmem); // unhook from previous position
3977
3978 if (zeroes_done == st_off)
3979 zeroes_done = next_init_off;
3980
3981 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3982
3983 #ifdef ASSERT
3984 // Various order invariants. Weaker than stores_are_sane because
3985 // a large constant tile can be filled in by smaller non-constant stores.
3986 assert(st_off >= last_init_off, "inits do not reverse");
3987 last_init_off = st_off;
3988 const Type* val = NULL;
3989 if (st_size >= BytesPerInt &&
3990 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3991 (int)val->basic_type() < (int)T_OBJECT) {
3992 assert(st_off >= last_tile_end, "tiles do not overlap");
3993 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3994 last_tile_end = MAX2(last_tile_end, next_init_off);
3995 } else {
3996 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3997 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3998 assert(st_off >= last_init_end, "inits do not overlap");
3999 last_init_end = next_init_off; // it's a non-tile
4000 }
4001 #endif //ASSERT
4002 }
4003
4004 remove_extra_zeroes(); // clear out all the zmems left over
4005 add_req(inits);
4006
4007 if (!ZeroTLAB) {
4008 // If anything remains to be zeroed, zero it all now.
4009 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4010 // if it is the last unused 4 bytes of an instance, forget about it
4011 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4012 if (zeroes_done + BytesPerLong >= size_limit) {
4013 assert(allocation() != NULL, "");
4014 if (allocation()->Opcode() == Op_Allocate) {
4015 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
4016 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4017 if (zeroes_done == k->layout_helper())
4018 zeroes_done = size_limit;
4019 }
4020 }
4021 if (zeroes_done < size_limit) {
4022 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4023 zeroes_done, size_in_bytes, phase);
4024 }
4025 }
4026
4027 set_complete(phase);
4028 return rawmem;
4029 }
4030
4031
4032 #ifdef ASSERT
4033 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4034 if (is_complete())
4035 return true; // stores could be anything at this point
4036 assert(allocation() != NULL, "must be present");
4037 intptr_t last_off = allocation()->minimum_header_size();
4038 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4039 Node* st = in(i);
4040 intptr_t st_off = get_store_offset(st, phase);
4041 if (st_off < 0) continue; // ignore dead garbage
4042 if (last_off > st_off) {
4043 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
4044 this->dump(2);
4045 assert(false, "ascending store offsets");
4046 return false;
4047 }
4048 last_off = st_off + st->as_Store()->memory_size();
4049 }
4050 return true;
4051 }
4052 #endif //ASSERT
4053
4054
4055
4056
4057 //============================MergeMemNode=====================================
4058 //
4059 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4060 // contributing store or call operations. Each contributor provides the memory
4061 // state for a particular "alias type" (see Compile::alias_type). For example,
4062 // if a MergeMem has an input X for alias category #6, then any memory reference
4063 // to alias category #6 may use X as its memory state input, as an exact equivalent
4064 // to using the MergeMem as a whole.
4065 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4066 //
4067 // (Here, the <N> notation gives the index of the relevant adr_type.)
4068 //
4069 // In one special case (and more cases in the future), alias categories overlap.
4070 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4071 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4072 // it is exactly equivalent to that state W:
4073 // MergeMem(<Bot>: W) <==> W
4074 //
4075 // Usually, the merge has more than one input. In that case, where inputs
4076 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4077 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4078 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4079 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4080 //
4081 // A merge can take a "wide" memory state as one of its narrow inputs.
4082 // This simply means that the merge observes out only the relevant parts of
4083 // the wide input. That is, wide memory states arriving at narrow merge inputs
4084 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4085 //
4086 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4087 // and that memory slices "leak through":
4088 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4089 //
4090 // But, in such a cascade, repeated memory slices can "block the leak":
4091 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4092 //
4093 // In the last example, Y is not part of the combined memory state of the
4094 // outermost MergeMem. The system must, of course, prevent unschedulable
4095 // memory states from arising, so you can be sure that the state Y is somehow
4096 // a precursor to state Y'.
4097 //
4098 //
4099 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4100 // of each MergeMemNode array are exactly the numerical alias indexes, including
4101 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4102 // Compile::alias_type (and kin) produce and manage these indexes.
4103 //
4104 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4105 // (Note that this provides quick access to the top node inside MergeMem methods,
4106 // without the need to reach out via TLS to Compile::current.)
4107 //
4108 // As a consequence of what was just described, a MergeMem that represents a full
4109 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4110 // containing all alias categories.
4111 //
4112 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4113 //
4114 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4115 // a memory state for the alias type <N>, or else the top node, meaning that
4116 // there is no particular input for that alias type. Note that the length of
4117 // a MergeMem is variable, and may be extended at any time to accommodate new
4118 // memory states at larger alias indexes. When merges grow, they are of course
4119 // filled with "top" in the unused in() positions.
4120 //
4121 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4122 // (Top was chosen because it works smoothly with passes like GCM.)
4123 //
4124 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4125 // the type of random VM bits like TLS references.) Since it is always the
4126 // first non-Bot memory slice, some low-level loops use it to initialize an
4127 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4128 //
4129 //
4130 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4131 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4132 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4133 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4134 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4135 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4136 //
4137 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4138 // really that different from the other memory inputs. An abbreviation called
4139 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4140 //
4141 //
4142 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4143 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4144 // that "emerges though" the base memory will be marked as excluding the alias types
4145 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4146 //
4147 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4148 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4149 //
4150 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4151 // (It is currently unimplemented.) As you can see, the resulting merge is
4152 // actually a disjoint union of memory states, rather than an overlay.
4153 //
4154
4155 //------------------------------MergeMemNode-----------------------------------
4156 Node* MergeMemNode::make_empty_memory() {
4157 Node* empty_memory = (Node*) Compile::current()->top();
4158 assert(empty_memory->is_top(), "correct sentinel identity");
4159 return empty_memory;
4160 }
4161
4162 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4163 init_class_id(Class_MergeMem);
4164 // all inputs are nullified in Node::Node(int)
4165 // set_input(0, NULL); // no control input
4166
4167 // Initialize the edges uniformly to top, for starters.
4168 Node* empty_mem = make_empty_memory();
4169 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4170 init_req(i,empty_mem);
4171 }
4172 assert(empty_memory() == empty_mem, "");
4173
4174 if( new_base != NULL && new_base->is_MergeMem() ) {
4175 MergeMemNode* mdef = new_base->as_MergeMem();
4176 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4177 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4178 mms.set_memory(mms.memory2());
4179 }
4180 assert(base_memory() == mdef->base_memory(), "");
4181 } else {
4182 set_base_memory(new_base);
4183 }
4184 }
4185
4186 // Make a new, untransformed MergeMem with the same base as 'mem'.
4187 // If mem is itself a MergeMem, populate the result with the same edges.
4188 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
4189 return new(C) MergeMemNode(mem);
4190 }
4191
4192 //------------------------------cmp--------------------------------------------
4193 uint MergeMemNode::hash() const { return NO_HASH; }
4194 uint MergeMemNode::cmp( const Node &n ) const {
4195 return (&n == this); // Always fail except on self
4196 }
4197
4198 //------------------------------Identity---------------------------------------
4199 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4200 // Identity if this merge point does not record any interesting memory
4201 // disambiguations.
4202 Node* base_mem = base_memory();
4203 Node* empty_mem = empty_memory();
4204 if (base_mem != empty_mem) { // Memory path is not dead?
4205 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4206 Node* mem = in(i);
4207 if (mem != empty_mem && mem != base_mem) {
4208 return this; // Many memory splits; no change
4209 }
4210 }
4211 }
4212 return base_mem; // No memory splits; ID on the one true input
4213 }
4214
4215 //------------------------------Ideal------------------------------------------
4216 // This method is invoked recursively on chains of MergeMem nodes
4217 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4218 // Remove chain'd MergeMems
4219 //
4220 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4221 // relative to the "in(Bot)". Since we are patching both at the same time,
4222 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4223 // but rewrite each "in(i)" relative to the new "in(Bot)".
4224 Node *progress = NULL;
4225
4226
4227 Node* old_base = base_memory();
4228 Node* empty_mem = empty_memory();
4229 if (old_base == empty_mem)
4230 return NULL; // Dead memory path.
4231
4232 MergeMemNode* old_mbase;
4233 if (old_base != NULL && old_base->is_MergeMem())
4234 old_mbase = old_base->as_MergeMem();
4235 else
4236 old_mbase = NULL;
4237 Node* new_base = old_base;
4238
4239 // simplify stacked MergeMems in base memory
4240 if (old_mbase) new_base = old_mbase->base_memory();
4241
4242 // the base memory might contribute new slices beyond my req()
4243 if (old_mbase) grow_to_match(old_mbase);
4244
4245 // Look carefully at the base node if it is a phi.
4246 PhiNode* phi_base;
4247 if (new_base != NULL && new_base->is_Phi())
4248 phi_base = new_base->as_Phi();
4249 else
4250 phi_base = NULL;
4251
4252 Node* phi_reg = NULL;
4253 uint phi_len = (uint)-1;
4254 if (phi_base != NULL && !phi_base->is_copy()) {
4255 // do not examine phi if degraded to a copy
4256 phi_reg = phi_base->region();
4257 phi_len = phi_base->req();
4258 // see if the phi is unfinished
4259 for (uint i = 1; i < phi_len; i++) {
4260 if (phi_base->in(i) == NULL) {
4261 // incomplete phi; do not look at it yet!
4262 phi_reg = NULL;
4263 phi_len = (uint)-1;
4264 break;
4265 }
4266 }
4267 }
4268
4269 // Note: We do not call verify_sparse on entry, because inputs
4270 // can normalize to the base_memory via subsume_node or similar
4271 // mechanisms. This method repairs that damage.
4272
4273 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4274
4275 // Look at each slice.
4276 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4277 Node* old_in = in(i);
4278 // calculate the old memory value
4279 Node* old_mem = old_in;
4280 if (old_mem == empty_mem) old_mem = old_base;
4281 assert(old_mem == memory_at(i), "");
4282
4283 // maybe update (reslice) the old memory value
4284
4285 // simplify stacked MergeMems
4286 Node* new_mem = old_mem;
4287 MergeMemNode* old_mmem;
4288 if (old_mem != NULL && old_mem->is_MergeMem())
4289 old_mmem = old_mem->as_MergeMem();
4290 else
4291 old_mmem = NULL;
4292 if (old_mmem == this) {
4293 // This can happen if loops break up and safepoints disappear.
4294 // A merge of BotPtr (default) with a RawPtr memory derived from a
4295 // safepoint can be rewritten to a merge of the same BotPtr with
4296 // the BotPtr phi coming into the loop. If that phi disappears
4297 // also, we can end up with a self-loop of the mergemem.
4298 // In general, if loops degenerate and memory effects disappear,
4299 // a mergemem can be left looking at itself. This simply means
4300 // that the mergemem's default should be used, since there is
4301 // no longer any apparent effect on this slice.
4302 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4303 // from start. Update the input to TOP.
4304 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4305 }
4306 else if (old_mmem != NULL) {
4307 new_mem = old_mmem->memory_at(i);
4308 }
4309 // else preceding memory was not a MergeMem
4310
4311 // replace equivalent phis (unfortunately, they do not GVN together)
4312 if (new_mem != NULL && new_mem != new_base &&
4313 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4314 if (new_mem->is_Phi()) {
4315 PhiNode* phi_mem = new_mem->as_Phi();
4316 for (uint i = 1; i < phi_len; i++) {
4317 if (phi_base->in(i) != phi_mem->in(i)) {
4318 phi_mem = NULL;
4319 break;
4320 }
4321 }
4322 if (phi_mem != NULL) {
4323 // equivalent phi nodes; revert to the def
4324 new_mem = new_base;
4325 }
4326 }
4327 }
4328
4329 // maybe store down a new value
4330 Node* new_in = new_mem;
4331 if (new_in == new_base) new_in = empty_mem;
4332
4333 if (new_in != old_in) {
4334 // Warning: Do not combine this "if" with the previous "if"
4335 // A memory slice might have be be rewritten even if it is semantically
4336 // unchanged, if the base_memory value has changed.
4337 set_req(i, new_in);
4338 progress = this; // Report progress
4339 }
4340 }
4341
4342 if (new_base != old_base) {
4343 set_req(Compile::AliasIdxBot, new_base);
4344 // Don't use set_base_memory(new_base), because we need to update du.
4345 assert(base_memory() == new_base, "");
4346 progress = this;
4347 }
4348
4349 if( base_memory() == this ) {
4350 // a self cycle indicates this memory path is dead
4351 set_req(Compile::AliasIdxBot, empty_mem);
4352 }
4353
4354 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4355 // Recursion must occur after the self cycle check above
4356 if( base_memory()->is_MergeMem() ) {
4357 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4358 Node *m = phase->transform(new_mbase); // Rollup any cycles
4359 if( m != NULL && (m->is_top() ||
4360 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4361 // propagate rollup of dead cycle to self
4362 set_req(Compile::AliasIdxBot, empty_mem);
4363 }
4364 }
4365
4366 if( base_memory() == empty_mem ) {
4367 progress = this;
4368 // Cut inputs during Parse phase only.
4369 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4370 if( !can_reshape ) {
4371 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4372 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4373 }
4374 }
4375 }
4376
4377 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4378 // Check if PhiNode::Ideal's "Split phis through memory merges"
4379 // transform should be attempted. Look for this->phi->this cycle.
4380 uint merge_width = req();
4381 if (merge_width > Compile::AliasIdxRaw) {
4382 PhiNode* phi = base_memory()->as_Phi();
4383 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4384 if (phi->in(i) == this) {
4385 phase->is_IterGVN()->_worklist.push(phi);
4386 break;
4387 }
4388 }
4389 }
4390 }
4391
4392 assert(progress || verify_sparse(), "please, no dups of base");
4393 return progress;
4394 }
4395
4396 //-------------------------set_base_memory-------------------------------------
4397 void MergeMemNode::set_base_memory(Node *new_base) {
4398 Node* empty_mem = empty_memory();
4399 set_req(Compile::AliasIdxBot, new_base);
4400 assert(memory_at(req()) == new_base, "must set default memory");
4401 // Clear out other occurrences of new_base:
4402 if (new_base != empty_mem) {
4403 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4404 if (in(i) == new_base) set_req(i, empty_mem);
4405 }
4406 }
4407 }
4408
4409 //------------------------------out_RegMask------------------------------------
4410 const RegMask &MergeMemNode::out_RegMask() const {
4411 return RegMask::Empty;
4412 }
4413
4414 //------------------------------dump_spec--------------------------------------
4415 #ifndef PRODUCT
4416 void MergeMemNode::dump_spec(outputStream *st) const {
4417 st->print(" {");
4418 Node* base_mem = base_memory();
4419 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4420 Node* mem = memory_at(i);
4421 if (mem == base_mem) { st->print(" -"); continue; }
4422 st->print( " N%d:", mem->_idx );
4423 Compile::current()->get_adr_type(i)->dump_on(st);
4424 }
4425 st->print(" }");
4426 }
4427 #endif // !PRODUCT
4428
4429
4430 #ifdef ASSERT
4431 static bool might_be_same(Node* a, Node* b) {
4432 if (a == b) return true;
4433 if (!(a->is_Phi() || b->is_Phi())) return false;
4434 // phis shift around during optimization
4435 return true; // pretty stupid...
4436 }
4437
4438 // verify a narrow slice (either incoming or outgoing)
4439 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4440 if (!VerifyAliases) return; // don't bother to verify unless requested
4441 if (is_error_reported()) return; // muzzle asserts when debugging an error
4442 if (Node::in_dump()) return; // muzzle asserts when printing
4443 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4444 assert(n != NULL, "");
4445 // Elide intervening MergeMem's
4446 while (n->is_MergeMem()) {
4447 n = n->as_MergeMem()->memory_at(alias_idx);
4448 }
4449 Compile* C = Compile::current();
4450 const TypePtr* n_adr_type = n->adr_type();
4451 if (n == m->empty_memory()) {
4452 // Implicit copy of base_memory()
4453 } else if (n_adr_type != TypePtr::BOTTOM) {
4454 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4455 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4456 } else {
4457 // A few places like make_runtime_call "know" that VM calls are narrow,
4458 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4459 bool expected_wide_mem = false;
4460 if (n == m->base_memory()) {
4461 expected_wide_mem = true;
4462 } else if (alias_idx == Compile::AliasIdxRaw ||
4463 n == m->memory_at(Compile::AliasIdxRaw)) {
4464 expected_wide_mem = true;
4465 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4466 // memory can "leak through" calls on channels that
4467 // are write-once. Allow this also.
4468 expected_wide_mem = true;
4469 }
4470 assert(expected_wide_mem, "expected narrow slice replacement");
4471 }
4472 }
4473 #else // !ASSERT
4474 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4475 #endif
4476
4477
4478 //-----------------------------memory_at---------------------------------------
4479 Node* MergeMemNode::memory_at(uint alias_idx) const {
4480 assert(alias_idx >= Compile::AliasIdxRaw ||
4481 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4482 "must avoid base_memory and AliasIdxTop");
4483
4484 // Otherwise, it is a narrow slice.
4485 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4486 Compile *C = Compile::current();
4487 if (is_empty_memory(n)) {
4488 // the array is sparse; empty slots are the "top" node
4489 n = base_memory();
4490 assert(Node::in_dump()
4491 || n == NULL || n->bottom_type() == Type::TOP
4492 || n->adr_type() == NULL // address is TOP
4493 || n->adr_type() == TypePtr::BOTTOM
4494 || n->adr_type() == TypeRawPtr::BOTTOM
4495 || Compile::current()->AliasLevel() == 0,
4496 "must be a wide memory");
4497 // AliasLevel == 0 if we are organizing the memory states manually.
4498 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4499 } else {
4500 // make sure the stored slice is sane
4501 #ifdef ASSERT
4502 if (is_error_reported() || Node::in_dump()) {
4503 } else if (might_be_same(n, base_memory())) {
4504 // Give it a pass: It is a mostly harmless repetition of the base.
4505 // This can arise normally from node subsumption during optimization.
4506 } else {
4507 verify_memory_slice(this, alias_idx, n);
4508 }
4509 #endif
4510 }
4511 return n;
4512 }
4513
4514 //---------------------------set_memory_at-------------------------------------
4515 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4516 verify_memory_slice(this, alias_idx, n);
4517 Node* empty_mem = empty_memory();
4518 if (n == base_memory()) n = empty_mem; // collapse default
4519 uint need_req = alias_idx+1;
4520 if (req() < need_req) {
4521 if (n == empty_mem) return; // already the default, so do not grow me
4522 // grow the sparse array
4523 do {
4524 add_req(empty_mem);
4525 } while (req() < need_req);
4526 }
4527 set_req( alias_idx, n );
4528 }
4529
4530
4531
4532 //--------------------------iteration_setup------------------------------------
4533 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4534 if (other != NULL) {
4535 grow_to_match(other);
4536 // invariant: the finite support of mm2 is within mm->req()
4537 #ifdef ASSERT
4538 for (uint i = req(); i < other->req(); i++) {
4539 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4540 }
4541 #endif
4542 }
4543 // Replace spurious copies of base_memory by top.
4544 Node* base_mem = base_memory();
4545 if (base_mem != NULL && !base_mem->is_top()) {
4546 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4547 if (in(i) == base_mem)
4548 set_req(i, empty_memory());
4549 }
4550 }
4551 }
4552
4553 //---------------------------grow_to_match-------------------------------------
4554 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4555 Node* empty_mem = empty_memory();
4556 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4557 // look for the finite support of the other memory
4558 for (uint i = other->req(); --i >= req(); ) {
4559 if (other->in(i) != empty_mem) {
4560 uint new_len = i+1;
4561 while (req() < new_len) add_req(empty_mem);
4562 break;
4563 }
4564 }
4565 }
4566
4567 //---------------------------verify_sparse-------------------------------------
4568 #ifndef PRODUCT
4569 bool MergeMemNode::verify_sparse() const {
4570 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4571 Node* base_mem = base_memory();
4572 // The following can happen in degenerate cases, since empty==top.
4573 if (is_empty_memory(base_mem)) return true;
4574 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4575 assert(in(i) != NULL, "sane slice");
4576 if (in(i) == base_mem) return false; // should have been the sentinel value!
4577 }
4578 return true;
4579 }
4580
4581 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4582 Node* n;
4583 n = mm->in(idx);
4584 if (mem == n) return true; // might be empty_memory()
4585 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4586 if (mem == n) return true;
4587 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4588 if (mem == n) return true;
4589 if (n == NULL) break;
4590 }
4591 return false;
4592 }
4593 #endif // !PRODUCT