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