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