1 /*
2 * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/objArrayKlass.hpp"
31 #include "opto/addnode.hpp"
32 #include "opto/arraycopynode.hpp"
33 #include "opto/cfgnode.hpp"
34 #include "opto/compile.hpp"
35 #include "opto/connode.hpp"
36 #include "opto/convertnode.hpp"
37 #include "opto/loopnode.hpp"
38 #include "opto/machnode.hpp"
39 #include "opto/matcher.hpp"
40 #include "opto/memnode.hpp"
41 #include "opto/mulnode.hpp"
42 #include "opto/narrowptrnode.hpp"
43 #include "opto/phaseX.hpp"
44 #include "opto/regmask.hpp"
45 #include "utilities/copy.hpp"
46
47 // Portions of code courtesy of Clifford Click
48
49 // Optimization - Graph Style
50
51 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
52
53 //=============================================================================
54 uint MemNode::size_of() const { return sizeof(*this); }
55
56 const TypePtr *MemNode::adr_type() const {
57 Node* adr = in(Address);
58 if (adr == NULL) return NULL; // node is dead
59 const TypePtr* cross_check = NULL;
60 DEBUG_ONLY(cross_check = _adr_type);
61 return calculate_adr_type(adr->bottom_type(), cross_check);
62 }
63
64 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
65 if (adr != NULL) {
66 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
67 return true;
68 }
69 }
70 return false;
71 }
72
73 #ifndef PRODUCT
74 void MemNode::dump_spec(outputStream *st) const {
75 if (in(Address) == NULL) return; // node is dead
76 #ifndef ASSERT
77 // fake the missing field
78 const TypePtr* _adr_type = NULL;
79 if (in(Address) != NULL)
80 _adr_type = in(Address)->bottom_type()->isa_ptr();
81 #endif
82 dump_adr_type(this, _adr_type, st);
83
84 Compile* C = Compile::current();
85 if (C->alias_type(_adr_type)->is_volatile()) {
86 st->print(" Volatile!");
87 }
88 if (_unaligned_access) {
89 st->print(" unaligned");
90 }
91 if (_mismatched_access) {
92 st->print(" mismatched");
93 }
94 }
95
96 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
97 st->print(" @");
98 if (adr_type == NULL) {
99 st->print("NULL");
100 } else {
101 adr_type->dump_on(st);
102 Compile* C = Compile::current();
103 Compile::AliasType* atp = NULL;
104 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
105 if (atp == NULL)
106 st->print(", idx=?\?;");
107 else if (atp->index() == Compile::AliasIdxBot)
108 st->print(", idx=Bot;");
109 else if (atp->index() == Compile::AliasIdxTop)
110 st->print(", idx=Top;");
111 else if (atp->index() == Compile::AliasIdxRaw)
112 st->print(", idx=Raw;");
113 else {
114 ciField* field = atp->field();
115 if (field) {
116 st->print(", name=");
117 field->print_name_on(st);
118 }
119 st->print(", idx=%d;", atp->index());
120 }
121 }
122 }
123
124 extern void print_alias_types();
125
126 #endif
127
128 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
129 assert((t_oop != NULL), "sanity");
130 bool is_instance = t_oop->is_known_instance_field();
131 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
132 (load != NULL) && load->is_Load() &&
133 (phase->is_IterGVN() != NULL);
134 if (!(is_instance || is_boxed_value_load))
135 return mchain; // don't try to optimize non-instance types
136 uint instance_id = t_oop->instance_id();
137 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
138 Node *prev = NULL;
139 Node *result = mchain;
140 while (prev != result) {
141 prev = result;
142 if (result == start_mem)
143 break; // hit one of our sentinels
144 // skip over a call which does not affect this memory slice
145 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
146 Node *proj_in = result->in(0);
147 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
148 break; // hit one of our sentinels
149 } else if (proj_in->is_Call()) {
150 // ArrayCopyNodes processed here as well
151 CallNode *call = proj_in->as_Call();
152 if (!call->may_modify(t_oop, phase)) { // returns false for instances
153 result = call->in(TypeFunc::Memory);
154 }
155 } else if (proj_in->is_Initialize()) {
156 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
157 // Stop if this is the initialization for the object instance which
158 // contains this memory slice, otherwise skip over it.
159 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
160 break;
161 }
162 if (is_instance) {
163 result = proj_in->in(TypeFunc::Memory);
164 } else if (is_boxed_value_load) {
165 Node* klass = alloc->in(AllocateNode::KlassNode);
166 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
167 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
168 result = proj_in->in(TypeFunc::Memory); // not related allocation
169 }
170 }
171 } else if (proj_in->is_MemBar()) {
172 ArrayCopyNode* ac = NULL;
173 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
174 break;
175 }
176 result = proj_in->in(TypeFunc::Memory);
177 } else {
178 assert(false, "unexpected projection");
179 }
180 } else if (result->is_ClearArray()) {
181 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
182 // Can not bypass initialization of the instance
183 // we are looking for.
184 break;
185 }
186 // Otherwise skip it (the call updated 'result' value).
187 } else if (result->is_MergeMem()) {
188 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
189 }
190 }
191 return result;
192 }
193
194 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
195 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
196 if (t_oop == NULL)
197 return mchain; // don't try to optimize non-oop types
198 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
199 bool is_instance = t_oop->is_known_instance_field();
200 PhaseIterGVN *igvn = phase->is_IterGVN();
201 if (is_instance && igvn != NULL && result->is_Phi()) {
202 PhiNode *mphi = result->as_Phi();
203 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
204 const TypePtr *t = mphi->adr_type();
205 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
206 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
207 t->is_oopptr()->cast_to_exactness(true)
208 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
209 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
210 // clone the Phi with our address type
211 result = mphi->split_out_instance(t_adr, igvn);
212 } else {
213 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
214 }
215 }
216 return result;
217 }
218
219 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
220 uint alias_idx = phase->C->get_alias_index(tp);
221 Node *mem = mmem;
222 #ifdef ASSERT
223 {
224 // Check that current type is consistent with the alias index used during graph construction
225 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
226 bool consistent = adr_check == NULL || adr_check->empty() ||
227 phase->C->must_alias(adr_check, alias_idx );
228 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
229 if( !consistent && adr_check != NULL && !adr_check->empty() &&
230 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
231 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
232 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
233 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
234 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
235 // don't assert if it is dead code.
236 consistent = true;
237 }
238 if( !consistent ) {
239 st->print("alias_idx==%d, adr_check==", alias_idx);
240 if( adr_check == NULL ) {
241 st->print("NULL");
242 } else {
243 adr_check->dump();
244 }
245 st->cr();
246 print_alias_types();
247 assert(consistent, "adr_check must match alias idx");
248 }
249 }
250 #endif
251 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
252 // means an array I have not precisely typed yet. Do not do any
253 // alias stuff with it any time soon.
254 const TypeOopPtr *toop = tp->isa_oopptr();
255 if( tp->base() != Type::AnyPtr &&
256 !(toop &&
257 toop->klass() != NULL &&
258 toop->klass()->is_java_lang_Object() &&
259 toop->offset() == Type::OffsetBot) ) {
260 // compress paths and change unreachable cycles to TOP
261 // If not, we can update the input infinitely along a MergeMem cycle
262 // Equivalent code in PhiNode::Ideal
263 Node* m = phase->transform(mmem);
264 // If transformed to a MergeMem, get the desired slice
265 // Otherwise the returned node represents memory for every slice
266 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
267 // Update input if it is progress over what we have now
268 }
269 return mem;
270 }
271
272 //--------------------------Ideal_common---------------------------------------
273 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
274 // Unhook non-raw memories from complete (macro-expanded) initializations.
275 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
276 // If our control input is a dead region, kill all below the region
277 Node *ctl = in(MemNode::Control);
278 if (ctl && remove_dead_region(phase, can_reshape))
279 return this;
280 ctl = in(MemNode::Control);
281 // Don't bother trying to transform a dead node
282 if (ctl && ctl->is_top()) return NodeSentinel;
283
284 PhaseIterGVN *igvn = phase->is_IterGVN();
285 // Wait if control on the worklist.
286 if (ctl && can_reshape && igvn != NULL) {
287 Node* bol = NULL;
288 Node* cmp = NULL;
289 if (ctl->in(0)->is_If()) {
290 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
291 bol = ctl->in(0)->in(1);
292 if (bol->is_Bool())
293 cmp = ctl->in(0)->in(1)->in(1);
294 }
295 if (igvn->_worklist.member(ctl) ||
296 (bol != NULL && igvn->_worklist.member(bol)) ||
297 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
298 // This control path may be dead.
299 // Delay this memory node transformation until the control is processed.
300 phase->is_IterGVN()->_worklist.push(this);
301 return NodeSentinel; // caller will return NULL
302 }
303 }
304 // Ignore if memory is dead, or self-loop
305 Node *mem = in(MemNode::Memory);
306 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
307 assert(mem != this, "dead loop in MemNode::Ideal");
308
309 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
310 // This memory slice may be dead.
311 // Delay this mem node transformation until the memory is processed.
312 phase->is_IterGVN()->_worklist.push(this);
313 return NodeSentinel; // caller will return NULL
314 }
315
316 Node *address = in(MemNode::Address);
317 const Type *t_adr = phase->type(address);
318 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
319
320 if (can_reshape && igvn != NULL &&
321 (igvn->_worklist.member(address) ||
322 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
323 // The address's base and type may change when the address is processed.
324 // Delay this mem node transformation until the address is processed.
325 phase->is_IterGVN()->_worklist.push(this);
326 return NodeSentinel; // caller will return NULL
327 }
328
329 // Do NOT remove or optimize the next lines: ensure a new alias index
330 // is allocated for an oop pointer type before Escape Analysis.
331 // Note: C++ will not remove it since the call has side effect.
332 if (t_adr->isa_oopptr()) {
333 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
334 }
335
336 Node* base = NULL;
337 if (address->is_AddP()) {
338 base = address->in(AddPNode::Base);
339 }
340 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
341 !t_adr->isa_rawptr()) {
342 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
343 // Skip this node optimization if its address has TOP base.
344 return NodeSentinel; // caller will return NULL
345 }
346
347 // Avoid independent memory operations
348 Node* old_mem = mem;
349
350 // The code which unhooks non-raw memories from complete (macro-expanded)
351 // initializations was removed. After macro-expansion all stores catched
352 // by Initialize node became raw stores and there is no information
353 // which memory slices they modify. So it is unsafe to move any memory
354 // operation above these stores. Also in most cases hooked non-raw memories
355 // were already unhooked by using information from detect_ptr_independence()
356 // and find_previous_store().
357
358 if (mem->is_MergeMem()) {
359 MergeMemNode* mmem = mem->as_MergeMem();
360 const TypePtr *tp = t_adr->is_ptr();
361
362 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
363 }
364
365 if (mem != old_mem) {
366 set_req(MemNode::Memory, mem);
367 if (can_reshape && old_mem->outcnt() == 0) {
368 igvn->_worklist.push(old_mem);
369 }
370 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
371 return this;
372 }
373
374 // let the subclass continue analyzing...
375 return NULL;
376 }
377
378 // Helper function for proving some simple control dominations.
379 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
380 // Already assumes that 'dom' is available at 'sub', and that 'sub'
381 // is not a constant (dominated by the method's StartNode).
382 // Used by MemNode::find_previous_store to prove that the
383 // control input of a memory operation predates (dominates)
384 // an allocation it wants to look past.
385 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
386 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
387 return false; // Conservative answer for dead code
388
389 // Check 'dom'. Skip Proj and CatchProj nodes.
390 dom = dom->find_exact_control(dom);
391 if (dom == NULL || dom->is_top())
392 return false; // Conservative answer for dead code
393
394 if (dom == sub) {
395 // For the case when, for example, 'sub' is Initialize and the original
396 // 'dom' is Proj node of the 'sub'.
397 return false;
398 }
399
400 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
401 return true;
402
403 // 'dom' dominates 'sub' if its control edge and control edges
404 // of all its inputs dominate or equal to sub's control edge.
405
406 // Currently 'sub' is either Allocate, Initialize or Start nodes.
407 // Or Region for the check in LoadNode::Ideal();
408 // 'sub' should have sub->in(0) != NULL.
409 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
410 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
411
412 // Get control edge of 'sub'.
413 Node* orig_sub = sub;
414 sub = sub->find_exact_control(sub->in(0));
415 if (sub == NULL || sub->is_top())
416 return false; // Conservative answer for dead code
417
418 assert(sub->is_CFG(), "expecting control");
419
420 if (sub == dom)
421 return true;
422
423 if (sub->is_Start() || sub->is_Root())
424 return false;
425
426 {
427 // Check all control edges of 'dom'.
428
429 ResourceMark rm;
430 Arena* arena = Thread::current()->resource_area();
431 Node_List nlist(arena);
432 Unique_Node_List dom_list(arena);
433
434 dom_list.push(dom);
435 bool only_dominating_controls = false;
436
437 for (uint next = 0; next < dom_list.size(); next++) {
438 Node* n = dom_list.at(next);
439 if (n == orig_sub)
440 return false; // One of dom's inputs dominated by sub.
441 if (!n->is_CFG() && n->pinned()) {
442 // Check only own control edge for pinned non-control nodes.
443 n = n->find_exact_control(n->in(0));
444 if (n == NULL || n->is_top())
445 return false; // Conservative answer for dead code
446 assert(n->is_CFG(), "expecting control");
447 dom_list.push(n);
448 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
449 only_dominating_controls = true;
450 } else if (n->is_CFG()) {
451 if (n->dominates(sub, nlist))
452 only_dominating_controls = true;
453 else
454 return false;
455 } else {
456 // First, own control edge.
457 Node* m = n->find_exact_control(n->in(0));
458 if (m != NULL) {
459 if (m->is_top())
460 return false; // Conservative answer for dead code
461 dom_list.push(m);
462 }
463 // Now, the rest of edges.
464 uint cnt = n->req();
465 for (uint i = 1; i < cnt; i++) {
466 m = n->find_exact_control(n->in(i));
467 if (m == NULL || m->is_top())
468 continue;
469 dom_list.push(m);
470 }
471 }
472 }
473 return only_dominating_controls;
474 }
475 }
476
477 //---------------------detect_ptr_independence---------------------------------
478 // Used by MemNode::find_previous_store to prove that two base
479 // pointers are never equal.
480 // The pointers are accompanied by their associated allocations,
481 // if any, which have been previously discovered by the caller.
482 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
483 Node* p2, AllocateNode* a2,
484 PhaseTransform* phase) {
485 // Attempt to prove that these two pointers cannot be aliased.
486 // They may both manifestly be allocations, and they should differ.
487 // Or, if they are not both allocations, they can be distinct constants.
488 // Otherwise, one is an allocation and the other a pre-existing value.
489 if (a1 == NULL && a2 == NULL) { // neither an allocation
490 return (p1 != p2) && p1->is_Con() && p2->is_Con();
491 } else if (a1 != NULL && a2 != NULL) { // both allocations
492 return (a1 != a2);
493 } else if (a1 != NULL) { // one allocation a1
494 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
495 return all_controls_dominate(p2, a1);
496 } else { //(a2 != NULL) // one allocation a2
497 return all_controls_dominate(p1, a2);
498 }
499 return false;
500 }
501
502
503 // Find an arraycopy that must have set (can_see_stored_value=true) or
504 // could have set (can_see_stored_value=false) the value for this load
505 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
506 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
507 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
508 Node* mb = mem->in(0);
509 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
510 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
511 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
512 if (ac->is_clonebasic()) {
513 intptr_t offset;
514 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
515 assert(alloc != NULL && (!ReduceBulkZeroing || alloc->initialization()->is_complete_with_arraycopy()), "broken allocation");
516 if (alloc == ld_alloc) {
517 return ac;
518 }
519 }
520 }
521 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
522 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
523
524 if (ac->is_arraycopy_validated() ||
525 ac->is_copyof_validated() ||
526 ac->is_copyofrange_validated()) {
527 Node* ld_addp = in(MemNode::Address);
528 if (ld_addp->is_AddP()) {
529 Node* ld_base = ld_addp->in(AddPNode::Address);
530 Node* ld_offs = ld_addp->in(AddPNode::Offset);
531
532 Node* dest = ac->in(ArrayCopyNode::Dest);
533
534 if (dest == ld_base) {
535 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
536 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
537 return ac;
538 }
539 if (!can_see_stored_value) {
540 mem = ac->in(TypeFunc::Memory);
541 }
542 }
543 }
544 }
545 }
546 return NULL;
547 }
548
549 // The logic for reordering loads and stores uses four steps:
550 // (a) Walk carefully past stores and initializations which we
551 // can prove are independent of this load.
552 // (b) Observe that the next memory state makes an exact match
553 // with self (load or store), and locate the relevant store.
554 // (c) Ensure that, if we were to wire self directly to the store,
555 // the optimizer would fold it up somehow.
556 // (d) Do the rewiring, and return, depending on some other part of
557 // the optimizer to fold up the load.
558 // This routine handles steps (a) and (b). Steps (c) and (d) are
559 // specific to loads and stores, so they are handled by the callers.
560 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
561 //
562 Node* MemNode::find_previous_store(PhaseTransform* phase) {
563 Node* ctrl = in(MemNode::Control);
564 Node* adr = in(MemNode::Address);
565 intptr_t offset = 0;
566 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
567 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
568
569 if (offset == Type::OffsetBot)
570 return NULL; // cannot unalias unless there are precise offsets
571
572 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
573 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
574
575 intptr_t size_in_bytes = memory_size();
576
577 Node* mem = in(MemNode::Memory); // start searching here...
578
579 int cnt = 50; // Cycle limiter
580 for (;;) { // While we can dance past unrelated stores...
581 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
582
583 Node* prev = mem;
584 if (mem->is_Store()) {
585 Node* st_adr = mem->in(MemNode::Address);
586 intptr_t st_offset = 0;
587 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
588 if (st_base == NULL)
589 break; // inscrutable pointer
590
591 // For raw accesses it's not enough to prove that constant offsets don't intersect.
592 // We need the bases to be the equal in order for the offset check to make sense.
593 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
594 break;
595 }
596
597 if (st_offset != offset && st_offset != Type::OffsetBot) {
598 const int MAX_STORE = BytesPerLong;
599 if (st_offset >= offset + size_in_bytes ||
600 st_offset <= offset - MAX_STORE ||
601 st_offset <= offset - mem->as_Store()->memory_size()) {
602 // Success: The offsets are provably independent.
603 // (You may ask, why not just test st_offset != offset and be done?
604 // The answer is that stores of different sizes can co-exist
605 // in the same sequence of RawMem effects. We sometimes initialize
606 // a whole 'tile' of array elements with a single jint or jlong.)
607 mem = mem->in(MemNode::Memory);
608 continue; // (a) advance through independent store memory
609 }
610 }
611 if (st_base != base &&
612 detect_ptr_independence(base, alloc,
613 st_base,
614 AllocateNode::Ideal_allocation(st_base, phase),
615 phase)) {
616 // Success: The bases are provably independent.
617 mem = mem->in(MemNode::Memory);
618 continue; // (a) advance through independent store memory
619 }
620
621 // (b) At this point, if the bases or offsets do not agree, we lose,
622 // since we have not managed to prove 'this' and 'mem' independent.
623 if (st_base == base && st_offset == offset) {
624 return mem; // let caller handle steps (c), (d)
625 }
626
627 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
628 InitializeNode* st_init = mem->in(0)->as_Initialize();
629 AllocateNode* st_alloc = st_init->allocation();
630 if (st_alloc == NULL)
631 break; // something degenerated
632 bool known_identical = false;
633 bool known_independent = false;
634 if (alloc == st_alloc)
635 known_identical = true;
636 else if (alloc != NULL)
637 known_independent = true;
638 else if (all_controls_dominate(this, st_alloc))
639 known_independent = true;
640
641 if (known_independent) {
642 // The bases are provably independent: Either they are
643 // manifestly distinct allocations, or else the control
644 // of this load dominates the store's allocation.
645 int alias_idx = phase->C->get_alias_index(adr_type());
646 if (alias_idx == Compile::AliasIdxRaw) {
647 mem = st_alloc->in(TypeFunc::Memory);
648 } else {
649 mem = st_init->memory(alias_idx);
650 }
651 continue; // (a) advance through independent store memory
652 }
653
654 // (b) at this point, if we are not looking at a store initializing
655 // the same allocation we are loading from, we lose.
656 if (known_identical) {
657 // From caller, can_see_stored_value will consult find_captured_store.
658 return mem; // let caller handle steps (c), (d)
659 }
660
661 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
662 if (prev != mem) {
663 // Found an arraycopy but it doesn't affect that load
664 continue;
665 }
666 // Found an arraycopy that may affect that load
667 return mem;
668 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
669 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
670 if (mem->is_Proj() && mem->in(0)->is_Call()) {
671 // ArrayCopyNodes processed here as well.
672 CallNode *call = mem->in(0)->as_Call();
673 if (!call->may_modify(addr_t, phase)) {
674 mem = call->in(TypeFunc::Memory);
675 continue; // (a) advance through independent call memory
676 }
677 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
678 ArrayCopyNode* ac = NULL;
679 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
680 break;
681 }
682 mem = mem->in(0)->in(TypeFunc::Memory);
683 continue; // (a) advance through independent MemBar memory
684 } else if (mem->is_ClearArray()) {
685 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
686 // (the call updated 'mem' value)
687 continue; // (a) advance through independent allocation memory
688 } else {
689 // Can not bypass initialization of the instance
690 // we are looking for.
691 return mem;
692 }
693 } else if (mem->is_MergeMem()) {
694 int alias_idx = phase->C->get_alias_index(adr_type());
695 mem = mem->as_MergeMem()->memory_at(alias_idx);
696 continue; // (a) advance through independent MergeMem memory
697 }
698 }
699
700 // Unless there is an explicit 'continue', we must bail out here,
701 // because 'mem' is an inscrutable memory state (e.g., a call).
702 break;
703 }
704
705 return NULL; // bail out
706 }
707
708 //----------------------calculate_adr_type-------------------------------------
709 // Helper function. Notices when the given type of address hits top or bottom.
710 // Also, asserts a cross-check of the type against the expected address type.
711 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
712 if (t == Type::TOP) return NULL; // does not touch memory any more?
713 #ifdef PRODUCT
714 cross_check = NULL;
715 #else
716 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
717 #endif
718 const TypePtr* tp = t->isa_ptr();
719 if (tp == NULL) {
720 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
721 return TypePtr::BOTTOM; // touches lots of memory
722 } else {
723 #ifdef ASSERT
724 // %%%% [phh] We don't check the alias index if cross_check is
725 // TypeRawPtr::BOTTOM. Needs to be investigated.
726 if (cross_check != NULL &&
727 cross_check != TypePtr::BOTTOM &&
728 cross_check != TypeRawPtr::BOTTOM) {
729 // Recheck the alias index, to see if it has changed (due to a bug).
730 Compile* C = Compile::current();
731 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
732 "must stay in the original alias category");
733 // The type of the address must be contained in the adr_type,
734 // disregarding "null"-ness.
735 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
736 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
737 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
738 "real address must not escape from expected memory type");
739 }
740 #endif
741 return tp;
742 }
743 }
744
745 //=============================================================================
746 // Should LoadNode::Ideal() attempt to remove control edges?
747 bool LoadNode::can_remove_control() const {
748 return true;
749 }
750 uint LoadNode::size_of() const { return sizeof(*this); }
751 uint LoadNode::cmp( const Node &n ) const
752 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
753 const Type *LoadNode::bottom_type() const { return _type; }
754 uint LoadNode::ideal_reg() const {
755 return _type->ideal_reg();
756 }
757
758 #ifndef PRODUCT
759 void LoadNode::dump_spec(outputStream *st) const {
760 MemNode::dump_spec(st);
761 if( !Verbose && !WizardMode ) {
762 // standard dump does this in Verbose and WizardMode
763 st->print(" #"); _type->dump_on(st);
764 }
765 if (!depends_only_on_test()) {
766 st->print(" (does not depend only on test)");
767 }
768 }
769 #endif
770
771 #ifdef ASSERT
772 //----------------------------is_immutable_value-------------------------------
773 // Helper function to allow a raw load without control edge for some cases
774 bool LoadNode::is_immutable_value(Node* adr) {
775 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
776 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
777 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
778 in_bytes(JavaThread::osthread_offset())));
779 }
780 #endif
781
782 //----------------------------LoadNode::make-----------------------------------
783 // Polymorphic factory method:
784 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
785 ControlDependency control_dependency, bool unaligned, bool mismatched) {
786 Compile* C = gvn.C;
787
788 // sanity check the alias category against the created node type
789 assert(!(adr_type->isa_oopptr() &&
790 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
791 "use LoadKlassNode instead");
792 assert(!(adr_type->isa_aryptr() &&
793 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
794 "use LoadRangeNode instead");
795 // Check control edge of raw loads
796 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
797 // oop will be recorded in oop map if load crosses safepoint
798 rt->isa_oopptr() || is_immutable_value(adr),
799 "raw memory operations should have control edge");
800 LoadNode* load = NULL;
801 switch (bt) {
802 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
803 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
804 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
805 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
806 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
807 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
808 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
809 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
810 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
811 case T_OBJECT:
812 #ifdef _LP64
813 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
814 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
815 } else
816 #endif
817 {
818 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
819 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
820 }
821 break;
822 }
823 assert(load != NULL, "LoadNode should have been created");
824 if (unaligned) {
825 load->set_unaligned_access();
826 }
827 if (mismatched) {
828 load->set_mismatched_access();
829 }
830 if (load->Opcode() == Op_LoadN) {
831 Node* ld = gvn.transform(load);
832 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
833 }
834
835 return load;
836 }
837
838 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
839 ControlDependency control_dependency, bool unaligned, bool mismatched) {
840 bool require_atomic = true;
841 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
842 if (unaligned) {
843 load->set_unaligned_access();
844 }
845 if (mismatched) {
846 load->set_mismatched_access();
847 }
848 return load;
849 }
850
851 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
852 ControlDependency control_dependency, bool unaligned, bool mismatched) {
853 bool require_atomic = true;
854 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
855 if (unaligned) {
856 load->set_unaligned_access();
857 }
858 if (mismatched) {
859 load->set_mismatched_access();
860 }
861 return load;
862 }
863
864
865
866 //------------------------------hash-------------------------------------------
867 uint LoadNode::hash() const {
868 // unroll addition of interesting fields
869 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
870 }
871
872 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
873 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
874 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
875 bool is_stable_ary = FoldStableValues &&
876 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
877 tp->isa_aryptr()->is_stable();
878
879 return (eliminate_boxing && non_volatile) || is_stable_ary;
880 }
881
882 return false;
883 }
884
885 // Is the value loaded previously stored by an arraycopy? If so return
886 // a load node that reads from the source array so we may be able to
887 // optimize out the ArrayCopy node later.
888 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const {
889 Node* ld_adr = in(MemNode::Address);
890 intptr_t ld_off = 0;
891 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
892 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
893 if (ac != NULL) {
894 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
895
896 Node* ld = clone();
897 if (ac->as_ArrayCopy()->is_clonebasic()) {
898 assert(ld_alloc != NULL, "need an alloc");
899 Node* addp = in(MemNode::Address)->clone();
900 assert(addp->is_AddP(), "address must be addp");
901 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
902 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
903 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base));
904 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address));
905 ld->set_req(MemNode::Address, phase->transform(addp));
906 if (in(0) != NULL) {
907 assert(ld_alloc->in(0) != NULL, "alloc must have control");
908 ld->set_req(0, ld_alloc->in(0));
909 }
910 } else {
911 Node* src = ac->in(ArrayCopyNode::Src);
912 Node* addp = in(MemNode::Address)->clone();
913 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
914 addp->set_req(AddPNode::Base, src);
915 addp->set_req(AddPNode::Address, src);
916
917 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
918 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
919 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
920 uint shift = exact_log2(type2aelembytes(ary_elem));
921
922 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
923 #ifdef _LP64
924 diff = phase->transform(new ConvI2LNode(diff));
925 #endif
926 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
927
928 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
929 addp->set_req(AddPNode::Offset, offset);
930 ld->set_req(MemNode::Address, phase->transform(addp));
931
932 const TypeX *ld_offs_t = phase->type(offset)->isa_intptr_t();
933
934 if (!ac->as_ArrayCopy()->can_replace_dest_load_with_src_load(ld_offs_t->_lo, ld_offs_t->_hi, phase)) {
935 return NULL;
936 }
937
938 if (in(0) != NULL) {
939 assert(ac->in(0) != NULL, "alloc must have control");
940 ld->set_req(0, ac->in(0));
941 }
942 }
943 // load depends on the tests that validate the arraycopy
944 ld->as_Load()->_control_dependency = Pinned;
945 return ld;
946 }
947 return NULL;
948 }
949
950
951 //---------------------------can_see_stored_value------------------------------
952 // This routine exists to make sure this set of tests is done the same
953 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
954 // will change the graph shape in a way which makes memory alive twice at the
955 // same time (uses the Oracle model of aliasing), then some
956 // LoadXNode::Identity will fold things back to the equivalence-class model
957 // of aliasing.
958 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
959 Node* ld_adr = in(MemNode::Address);
960 intptr_t ld_off = 0;
961 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
962 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
963 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
964 // This is more general than load from boxing objects.
965 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
966 uint alias_idx = atp->index();
967 bool final = !atp->is_rewritable();
968 Node* result = NULL;
969 Node* current = st;
970 // Skip through chains of MemBarNodes checking the MergeMems for
971 // new states for the slice of this load. Stop once any other
972 // kind of node is encountered. Loads from final memory can skip
973 // through any kind of MemBar but normal loads shouldn't skip
974 // through MemBarAcquire since the could allow them to move out of
975 // a synchronized region.
976 while (current->is_Proj()) {
977 int opc = current->in(0)->Opcode();
978 if ((final && (opc == Op_MemBarAcquire ||
979 opc == Op_MemBarAcquireLock ||
980 opc == Op_LoadFence)) ||
981 opc == Op_MemBarRelease ||
982 opc == Op_StoreFence ||
983 opc == Op_MemBarReleaseLock ||
984 opc == Op_MemBarStoreStore ||
985 opc == Op_MemBarCPUOrder) {
986 Node* mem = current->in(0)->in(TypeFunc::Memory);
987 if (mem->is_MergeMem()) {
988 MergeMemNode* merge = mem->as_MergeMem();
989 Node* new_st = merge->memory_at(alias_idx);
990 if (new_st == merge->base_memory()) {
991 // Keep searching
992 current = new_st;
993 continue;
994 }
995 // Save the new memory state for the slice and fall through
996 // to exit.
997 result = new_st;
998 }
999 }
1000 break;
1001 }
1002 if (result != NULL) {
1003 st = result;
1004 }
1005 }
1006
1007 // Loop around twice in the case Load -> Initialize -> Store.
1008 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1009 for (int trip = 0; trip <= 1; trip++) {
1010
1011 if (st->is_Store()) {
1012 Node* st_adr = st->in(MemNode::Address);
1013 if (!phase->eqv(st_adr, ld_adr)) {
1014 // Try harder before giving up... Match raw and non-raw pointers.
1015 intptr_t st_off = 0;
1016 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1017 if (alloc == NULL) return NULL;
1018 if (alloc != ld_alloc) return NULL;
1019 if (ld_off != st_off) return NULL;
1020 // At this point we have proven something like this setup:
1021 // A = Allocate(...)
1022 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1023 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1024 // (Actually, we haven't yet proven the Q's are the same.)
1025 // In other words, we are loading from a casted version of
1026 // the same pointer-and-offset that we stored to.
1027 // Thus, we are able to replace L by V.
1028 }
1029 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1030 if (store_Opcode() != st->Opcode())
1031 return NULL;
1032 return st->in(MemNode::ValueIn);
1033 }
1034
1035 // A load from a freshly-created object always returns zero.
1036 // (This can happen after LoadNode::Ideal resets the load's memory input
1037 // to find_captured_store, which returned InitializeNode::zero_memory.)
1038 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1039 (st->in(0) == ld_alloc) &&
1040 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1041 // return a zero value for the load's basic type
1042 // (This is one of the few places where a generic PhaseTransform
1043 // can create new nodes. Think of it as lazily manifesting
1044 // virtually pre-existing constants.)
1045 return phase->zerocon(memory_type());
1046 }
1047
1048 // A load from an initialization barrier can match a captured store.
1049 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1050 InitializeNode* init = st->in(0)->as_Initialize();
1051 AllocateNode* alloc = init->allocation();
1052 if ((alloc != NULL) && (alloc == ld_alloc)) {
1053 // examine a captured store value
1054 st = init->find_captured_store(ld_off, memory_size(), phase);
1055 if (st != NULL) {
1056 continue; // take one more trip around
1057 }
1058 }
1059 }
1060
1061 // Load boxed value from result of valueOf() call is input parameter.
1062 if (this->is_Load() && ld_adr->is_AddP() &&
1063 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1064 intptr_t ignore = 0;
1065 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1066 if (base != NULL && base->is_Proj() &&
1067 base->as_Proj()->_con == TypeFunc::Parms &&
1068 base->in(0)->is_CallStaticJava() &&
1069 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1070 return base->in(0)->in(TypeFunc::Parms);
1071 }
1072 }
1073
1074 break;
1075 }
1076
1077 return NULL;
1078 }
1079
1080 //----------------------is_instance_field_load_with_local_phi------------------
1081 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1082 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1083 in(Address)->is_AddP() ) {
1084 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1085 // Only instances and boxed values.
1086 if( t_oop != NULL &&
1087 (t_oop->is_ptr_to_boxed_value() ||
1088 t_oop->is_known_instance_field()) &&
1089 t_oop->offset() != Type::OffsetBot &&
1090 t_oop->offset() != Type::OffsetTop) {
1091 return true;
1092 }
1093 }
1094 return false;
1095 }
1096
1097 //------------------------------Identity---------------------------------------
1098 // Loads are identity if previous store is to same address
1099 Node* LoadNode::Identity(PhaseGVN* phase) {
1100 // If the previous store-maker is the right kind of Store, and the store is
1101 // to the same address, then we are equal to the value stored.
1102 Node* mem = in(Memory);
1103 Node* value = can_see_stored_value(mem, phase);
1104 if( value ) {
1105 // byte, short & char stores truncate naturally.
1106 // A load has to load the truncated value which requires
1107 // some sort of masking operation and that requires an
1108 // Ideal call instead of an Identity call.
1109 if (memory_size() < BytesPerInt) {
1110 // If the input to the store does not fit with the load's result type,
1111 // it must be truncated via an Ideal call.
1112 if (!phase->type(value)->higher_equal(phase->type(this)))
1113 return this;
1114 }
1115 // (This works even when value is a Con, but LoadNode::Value
1116 // usually runs first, producing the singleton type of the Con.)
1117 return value;
1118 }
1119
1120 // Search for an existing data phi which was generated before for the same
1121 // instance's field to avoid infinite generation of phis in a loop.
1122 Node *region = mem->in(0);
1123 if (is_instance_field_load_with_local_phi(region)) {
1124 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1125 int this_index = phase->C->get_alias_index(addr_t);
1126 int this_offset = addr_t->offset();
1127 int this_iid = addr_t->instance_id();
1128 if (!addr_t->is_known_instance() &&
1129 addr_t->is_ptr_to_boxed_value()) {
1130 // Use _idx of address base (could be Phi node) for boxed values.
1131 intptr_t ignore = 0;
1132 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1133 if (base == NULL) {
1134 return this;
1135 }
1136 this_iid = base->_idx;
1137 }
1138 const Type* this_type = bottom_type();
1139 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1140 Node* phi = region->fast_out(i);
1141 if (phi->is_Phi() && phi != mem &&
1142 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1143 return phi;
1144 }
1145 }
1146 }
1147
1148 return this;
1149 }
1150
1151 // Construct an equivalent unsigned load.
1152 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1153 BasicType bt = T_ILLEGAL;
1154 const Type* rt = NULL;
1155 switch (Opcode()) {
1156 case Op_LoadUB: return this;
1157 case Op_LoadUS: return this;
1158 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1159 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1160 default:
1161 assert(false, "no unsigned variant: %s", Name());
1162 return NULL;
1163 }
1164 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1165 raw_adr_type(), rt, bt, _mo, _control_dependency,
1166 is_unaligned_access(), is_mismatched_access());
1167 }
1168
1169 // Construct an equivalent signed load.
1170 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1171 BasicType bt = T_ILLEGAL;
1172 const Type* rt = NULL;
1173 switch (Opcode()) {
1174 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1175 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1176 case Op_LoadB: // fall through
1177 case Op_LoadS: // fall through
1178 case Op_LoadI: // fall through
1179 case Op_LoadL: return this;
1180 default:
1181 assert(false, "no signed variant: %s", Name());
1182 return NULL;
1183 }
1184 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1185 raw_adr_type(), rt, bt, _mo, _control_dependency,
1186 is_unaligned_access(), is_mismatched_access());
1187 }
1188
1189 // We're loading from an object which has autobox behaviour.
1190 // If this object is result of a valueOf call we'll have a phi
1191 // merging a newly allocated object and a load from the cache.
1192 // We want to replace this load with the original incoming
1193 // argument to the valueOf call.
1194 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1195 assert(phase->C->eliminate_boxing(), "sanity");
1196 intptr_t ignore = 0;
1197 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1198 if ((base == NULL) || base->is_Phi()) {
1199 // Push the loads from the phi that comes from valueOf up
1200 // through it to allow elimination of the loads and the recovery
1201 // of the original value. It is done in split_through_phi().
1202 return NULL;
1203 } else if (base->is_Load() ||
1204 base->is_DecodeN() && base->in(1)->is_Load()) {
1205 // Eliminate the load of boxed value for integer types from the cache
1206 // array by deriving the value from the index into the array.
1207 // Capture the offset of the load and then reverse the computation.
1208
1209 // Get LoadN node which loads a boxing object from 'cache' array.
1210 if (base->is_DecodeN()) {
1211 base = base->in(1);
1212 }
1213 if (!base->in(Address)->is_AddP()) {
1214 return NULL; // Complex address
1215 }
1216 AddPNode* address = base->in(Address)->as_AddP();
1217 Node* cache_base = address->in(AddPNode::Base);
1218 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1219 // Get ConP node which is static 'cache' field.
1220 cache_base = cache_base->in(1);
1221 }
1222 if ((cache_base != NULL) && cache_base->is_Con()) {
1223 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1224 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1225 Node* elements[4];
1226 int shift = exact_log2(type2aelembytes(T_OBJECT));
1227 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1228 if ((count > 0) && elements[0]->is_Con() &&
1229 ((count == 1) ||
1230 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1231 elements[1]->in(2) == phase->intcon(shift))) {
1232 ciObjArray* array = base_type->const_oop()->as_obj_array();
1233 // Fetch the box object cache[0] at the base of the array and get its value
1234 ciInstance* box = array->obj_at(0)->as_instance();
1235 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1236 assert(ik->is_box_klass(), "sanity");
1237 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1238 if (ik->nof_nonstatic_fields() == 1) {
1239 // This should be true nonstatic_field_at requires calling
1240 // nof_nonstatic_fields so check it anyway
1241 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1242 BasicType bt = c.basic_type();
1243 // Only integer types have boxing cache.
1244 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1245 bt == T_BYTE || bt == T_SHORT ||
1246 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1247 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1248 if (cache_low != (int)cache_low) {
1249 return NULL; // should not happen since cache is array indexed by value
1250 }
1251 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1252 if (offset != (int)offset) {
1253 return NULL; // should not happen since cache is array indexed by value
1254 }
1255 // Add up all the offsets making of the address of the load
1256 Node* result = elements[0];
1257 for (int i = 1; i < count; i++) {
1258 result = phase->transform(new AddXNode(result, elements[i]));
1259 }
1260 // Remove the constant offset from the address and then
1261 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1262 // remove the scaling of the offset to recover the original index.
1263 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1264 // Peel the shift off directly but wrap it in a dummy node
1265 // since Ideal can't return existing nodes
1266 result = new RShiftXNode(result->in(1), phase->intcon(0));
1267 } else if (result->is_Add() && result->in(2)->is_Con() &&
1268 result->in(1)->Opcode() == Op_LShiftX &&
1269 result->in(1)->in(2) == phase->intcon(shift)) {
1270 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1271 // but for boxing cache access we know that X<<Z will not overflow
1272 // (there is range check) so we do this optimizatrion by hand here.
1273 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1274 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1275 } else {
1276 result = new RShiftXNode(result, phase->intcon(shift));
1277 }
1278 #ifdef _LP64
1279 if (bt != T_LONG) {
1280 result = new ConvL2INode(phase->transform(result));
1281 }
1282 #else
1283 if (bt == T_LONG) {
1284 result = new ConvI2LNode(phase->transform(result));
1285 }
1286 #endif
1287 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1288 // Need to preserve unboxing load type if it is unsigned.
1289 switch(this->Opcode()) {
1290 case Op_LoadUB:
1291 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1292 break;
1293 case Op_LoadUS:
1294 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1295 break;
1296 }
1297 return result;
1298 }
1299 }
1300 }
1301 }
1302 }
1303 return NULL;
1304 }
1305
1306 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1307 Node* region = phi->in(0);
1308 if (region == NULL) {
1309 return false; // Wait stable graph
1310 }
1311 uint cnt = phi->req();
1312 for (uint i = 1; i < cnt; i++) {
1313 Node* rc = region->in(i);
1314 if (rc == NULL || phase->type(rc) == Type::TOP)
1315 return false; // Wait stable graph
1316 Node* in = phi->in(i);
1317 if (in == NULL || phase->type(in) == Type::TOP)
1318 return false; // Wait stable graph
1319 }
1320 return true;
1321 }
1322 //------------------------------split_through_phi------------------------------
1323 // Split instance or boxed field load through Phi.
1324 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1325 Node* mem = in(Memory);
1326 Node* address = in(Address);
1327 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1328
1329 assert((t_oop != NULL) &&
1330 (t_oop->is_known_instance_field() ||
1331 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1332
1333 Compile* C = phase->C;
1334 intptr_t ignore = 0;
1335 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1336 bool base_is_phi = (base != NULL) && base->is_Phi();
1337 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1338 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1339 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1340
1341 if (!((mem->is_Phi() || base_is_phi) &&
1342 (load_boxed_values || t_oop->is_known_instance_field()))) {
1343 return NULL; // memory is not Phi
1344 }
1345
1346 if (mem->is_Phi()) {
1347 if (!stable_phi(mem->as_Phi(), phase)) {
1348 return NULL; // Wait stable graph
1349 }
1350 uint cnt = mem->req();
1351 // Check for loop invariant memory.
1352 if (cnt == 3) {
1353 for (uint i = 1; i < cnt; i++) {
1354 Node* in = mem->in(i);
1355 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1356 if (m == mem) {
1357 set_req(Memory, mem->in(cnt - i));
1358 return this; // made change
1359 }
1360 }
1361 }
1362 }
1363 if (base_is_phi) {
1364 if (!stable_phi(base->as_Phi(), phase)) {
1365 return NULL; // Wait stable graph
1366 }
1367 uint cnt = base->req();
1368 // Check for loop invariant memory.
1369 if (cnt == 3) {
1370 for (uint i = 1; i < cnt; i++) {
1371 if (base->in(i) == base) {
1372 return NULL; // Wait stable graph
1373 }
1374 }
1375 }
1376 }
1377
1378 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1379
1380 // Split through Phi (see original code in loopopts.cpp).
1381 assert(C->have_alias_type(t_oop), "instance should have alias type");
1382
1383 // Do nothing here if Identity will find a value
1384 // (to avoid infinite chain of value phis generation).
1385 if (!phase->eqv(this, this->Identity(phase)))
1386 return NULL;
1387
1388 // Select Region to split through.
1389 Node* region;
1390 if (!base_is_phi) {
1391 assert(mem->is_Phi(), "sanity");
1392 region = mem->in(0);
1393 // Skip if the region dominates some control edge of the address.
1394 if (!MemNode::all_controls_dominate(address, region))
1395 return NULL;
1396 } else if (!mem->is_Phi()) {
1397 assert(base_is_phi, "sanity");
1398 region = base->in(0);
1399 // Skip if the region dominates some control edge of the memory.
1400 if (!MemNode::all_controls_dominate(mem, region))
1401 return NULL;
1402 } else if (base->in(0) != mem->in(0)) {
1403 assert(base_is_phi && mem->is_Phi(), "sanity");
1404 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1405 region = base->in(0);
1406 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1407 region = mem->in(0);
1408 } else {
1409 return NULL; // complex graph
1410 }
1411 } else {
1412 assert(base->in(0) == mem->in(0), "sanity");
1413 region = mem->in(0);
1414 }
1415
1416 const Type* this_type = this->bottom_type();
1417 int this_index = C->get_alias_index(t_oop);
1418 int this_offset = t_oop->offset();
1419 int this_iid = t_oop->instance_id();
1420 if (!t_oop->is_known_instance() && load_boxed_values) {
1421 // Use _idx of address base for boxed values.
1422 this_iid = base->_idx;
1423 }
1424 PhaseIterGVN* igvn = phase->is_IterGVN();
1425 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1426 for (uint i = 1; i < region->req(); i++) {
1427 Node* x;
1428 Node* the_clone = NULL;
1429 if (region->in(i) == C->top()) {
1430 x = C->top(); // Dead path? Use a dead data op
1431 } else {
1432 x = this->clone(); // Else clone up the data op
1433 the_clone = x; // Remember for possible deletion.
1434 // Alter data node to use pre-phi inputs
1435 if (this->in(0) == region) {
1436 x->set_req(0, region->in(i));
1437 } else {
1438 x->set_req(0, NULL);
1439 }
1440 if (mem->is_Phi() && (mem->in(0) == region)) {
1441 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1442 }
1443 if (address->is_Phi() && address->in(0) == region) {
1444 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1445 }
1446 if (base_is_phi && (base->in(0) == region)) {
1447 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1448 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1449 x->set_req(Address, adr_x);
1450 }
1451 }
1452 // Check for a 'win' on some paths
1453 const Type *t = x->Value(igvn);
1454
1455 bool singleton = t->singleton();
1456
1457 // See comments in PhaseIdealLoop::split_thru_phi().
1458 if (singleton && t == Type::TOP) {
1459 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1460 }
1461
1462 if (singleton) {
1463 x = igvn->makecon(t);
1464 } else {
1465 // We now call Identity to try to simplify the cloned node.
1466 // Note that some Identity methods call phase->type(this).
1467 // Make sure that the type array is big enough for
1468 // our new node, even though we may throw the node away.
1469 // (This tweaking with igvn only works because x is a new node.)
1470 igvn->set_type(x, t);
1471 // If x is a TypeNode, capture any more-precise type permanently into Node
1472 // otherwise it will be not updated during igvn->transform since
1473 // igvn->type(x) is set to x->Value() already.
1474 x->raise_bottom_type(t);
1475 Node *y = x->Identity(igvn);
1476 if (y != x) {
1477 x = y;
1478 } else {
1479 y = igvn->hash_find_insert(x);
1480 if (y) {
1481 x = y;
1482 } else {
1483 // Else x is a new node we are keeping
1484 // We do not need register_new_node_with_optimizer
1485 // because set_type has already been called.
1486 igvn->_worklist.push(x);
1487 }
1488 }
1489 }
1490 if (x != the_clone && the_clone != NULL) {
1491 igvn->remove_dead_node(the_clone);
1492 }
1493 phi->set_req(i, x);
1494 }
1495 // Record Phi
1496 igvn->register_new_node_with_optimizer(phi);
1497 return phi;
1498 }
1499
1500 //------------------------------Ideal------------------------------------------
1501 // If the load is from Field memory and the pointer is non-null, it might be possible to
1502 // zero out the control input.
1503 // If the offset is constant and the base is an object allocation,
1504 // try to hook me up to the exact initializing store.
1505 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1506 Node* p = MemNode::Ideal_common(phase, can_reshape);
1507 if (p) return (p == NodeSentinel) ? NULL : p;
1508
1509 Node* ctrl = in(MemNode::Control);
1510 Node* address = in(MemNode::Address);
1511 bool progress = false;
1512
1513 // Skip up past a SafePoint control. Cannot do this for Stores because
1514 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1515 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1516 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1517 ctrl = ctrl->in(0);
1518 set_req(MemNode::Control,ctrl);
1519 progress = true;
1520 }
1521
1522 intptr_t ignore = 0;
1523 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1524 if (base != NULL
1525 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1526 // Check for useless control edge in some common special cases
1527 if (in(MemNode::Control) != NULL
1528 && can_remove_control()
1529 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1530 && all_controls_dominate(base, phase->C->start())) {
1531 // A method-invariant, non-null address (constant or 'this' argument).
1532 set_req(MemNode::Control, NULL);
1533 progress = true;
1534 }
1535 }
1536
1537 Node* mem = in(MemNode::Memory);
1538 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1539
1540 if (can_reshape && (addr_t != NULL)) {
1541 // try to optimize our memory input
1542 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1543 if (opt_mem != mem) {
1544 set_req(MemNode::Memory, opt_mem);
1545 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1546 return this;
1547 }
1548 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1549 if ((t_oop != NULL) &&
1550 (t_oop->is_known_instance_field() ||
1551 t_oop->is_ptr_to_boxed_value())) {
1552 PhaseIterGVN *igvn = phase->is_IterGVN();
1553 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1554 // Delay this transformation until memory Phi is processed.
1555 phase->is_IterGVN()->_worklist.push(this);
1556 return NULL;
1557 }
1558 // Split instance field load through Phi.
1559 Node* result = split_through_phi(phase);
1560 if (result != NULL) return result;
1561
1562 if (t_oop->is_ptr_to_boxed_value()) {
1563 Node* result = eliminate_autobox(phase);
1564 if (result != NULL) return result;
1565 }
1566 }
1567 }
1568
1569 // Is there a dominating load that loads the same value? Leave
1570 // anything that is not a load of a field/array element (like
1571 // barriers etc.) alone
1572 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1573 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1574 Node *use = mem->fast_out(i);
1575 if (use != this &&
1576 use->Opcode() == Opcode() &&
1577 use->in(0) != NULL &&
1578 use->in(0) != in(0) &&
1579 use->in(Address) == in(Address)) {
1580 Node* ctl = in(0);
1581 for (int i = 0; i < 10 && ctl != NULL; i++) {
1582 ctl = IfNode::up_one_dom(ctl);
1583 if (ctl == use->in(0)) {
1584 set_req(0, use->in(0));
1585 return this;
1586 }
1587 }
1588 }
1589 }
1590 }
1591
1592 // Check for prior store with a different base or offset; make Load
1593 // independent. Skip through any number of them. Bail out if the stores
1594 // are in an endless dead cycle and report no progress. This is a key
1595 // transform for Reflection. However, if after skipping through the Stores
1596 // we can't then fold up against a prior store do NOT do the transform as
1597 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1598 // array memory alive twice: once for the hoisted Load and again after the
1599 // bypassed Store. This situation only works if EVERYBODY who does
1600 // anti-dependence work knows how to bypass. I.e. we need all
1601 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1602 // the alias index stuff. So instead, peek through Stores and IFF we can
1603 // fold up, do so.
1604 Node* prev_mem = find_previous_store(phase);
1605 if (prev_mem != NULL) {
1606 Node* value = can_see_arraycopy_value(prev_mem, phase);
1607 if (value != NULL) {
1608 return value;
1609 }
1610 }
1611 // Steps (a), (b): Walk past independent stores to find an exact match.
1612 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1613 // (c) See if we can fold up on the spot, but don't fold up here.
1614 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1615 // just return a prior value, which is done by Identity calls.
1616 if (can_see_stored_value(prev_mem, phase)) {
1617 // Make ready for step (d):
1618 set_req(MemNode::Memory, prev_mem);
1619 return this;
1620 }
1621 }
1622
1623 return progress ? this : NULL;
1624 }
1625
1626 // Helper to recognize certain Klass fields which are invariant across
1627 // some group of array types (e.g., int[] or all T[] where T < Object).
1628 const Type*
1629 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1630 ciKlass* klass) const {
1631 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1632 // The field is Klass::_modifier_flags. Return its (constant) value.
1633 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1634 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1635 return TypeInt::make(klass->modifier_flags());
1636 }
1637 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1638 // The field is Klass::_access_flags. Return its (constant) value.
1639 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1640 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1641 return TypeInt::make(klass->access_flags());
1642 }
1643 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1644 // The field is Klass::_layout_helper. Return its constant value if known.
1645 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1646 return TypeInt::make(klass->layout_helper());
1647 }
1648
1649 // No match.
1650 return NULL;
1651 }
1652
1653 //------------------------------Value-----------------------------------------
1654 const Type* LoadNode::Value(PhaseGVN* phase) const {
1655 // Either input is TOP ==> the result is TOP
1656 Node* mem = in(MemNode::Memory);
1657 const Type *t1 = phase->type(mem);
1658 if (t1 == Type::TOP) return Type::TOP;
1659 Node* adr = in(MemNode::Address);
1660 const TypePtr* tp = phase->type(adr)->isa_ptr();
1661 if (tp == NULL || tp->empty()) return Type::TOP;
1662 int off = tp->offset();
1663 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1664 Compile* C = phase->C;
1665
1666 // Try to guess loaded type from pointer type
1667 if (tp->isa_aryptr()) {
1668 const TypeAryPtr* ary = tp->is_aryptr();
1669 const Type* t = ary->elem();
1670
1671 // Determine whether the reference is beyond the header or not, by comparing
1672 // the offset against the offset of the start of the array's data.
1673 // Different array types begin at slightly different offsets (12 vs. 16).
1674 // We choose T_BYTE as an example base type that is least restrictive
1675 // as to alignment, which will therefore produce the smallest
1676 // possible base offset.
1677 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1678 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1679
1680 // Try to constant-fold a stable array element.
1681 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1682 // Make sure the reference is not into the header and the offset is constant
1683 ciObject* aobj = ary->const_oop();
1684 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1685 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1686 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1687 stable_dimension,
1688 memory_type(), is_unsigned());
1689 if (con_type != NULL) {
1690 return con_type;
1691 }
1692 }
1693 }
1694
1695 // Don't do this for integer types. There is only potential profit if
1696 // the element type t is lower than _type; that is, for int types, if _type is
1697 // more restrictive than t. This only happens here if one is short and the other
1698 // char (both 16 bits), and in those cases we've made an intentional decision
1699 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1700 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1701 //
1702 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1703 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1704 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1705 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1706 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1707 // In fact, that could have been the original type of p1, and p1 could have
1708 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1709 // expression (LShiftL quux 3) independently optimized to the constant 8.
1710 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1711 && (_type->isa_vect() == NULL)
1712 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1713 // t might actually be lower than _type, if _type is a unique
1714 // concrete subclass of abstract class t.
1715 if (off_beyond_header) { // is the offset beyond the header?
1716 const Type* jt = t->join_speculative(_type);
1717 // In any case, do not allow the join, per se, to empty out the type.
1718 if (jt->empty() && !t->empty()) {
1719 // This can happen if a interface-typed array narrows to a class type.
1720 jt = _type;
1721 }
1722 #ifdef ASSERT
1723 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1724 // The pointers in the autobox arrays are always non-null
1725 Node* base = adr->in(AddPNode::Base);
1726 if ((base != NULL) && base->is_DecodeN()) {
1727 // Get LoadN node which loads IntegerCache.cache field
1728 base = base->in(1);
1729 }
1730 if ((base != NULL) && base->is_Con()) {
1731 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1732 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1733 // It could be narrow oop
1734 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1735 }
1736 }
1737 }
1738 #endif
1739 return jt;
1740 }
1741 }
1742 } else if (tp->base() == Type::InstPtr) {
1743 assert( off != Type::OffsetBot ||
1744 // arrays can be cast to Objects
1745 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1746 // unsafe field access may not have a constant offset
1747 C->has_unsafe_access(),
1748 "Field accesses must be precise" );
1749 // For oop loads, we expect the _type to be precise.
1750
1751 // Optimize loads from constant fields.
1752 const TypeInstPtr* tinst = tp->is_instptr();
1753 ciObject* const_oop = tinst->const_oop();
1754 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1755 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1756 if (con_type != NULL) {
1757 return con_type;
1758 }
1759 }
1760 } else if (tp->base() == Type::KlassPtr) {
1761 assert( off != Type::OffsetBot ||
1762 // arrays can be cast to Objects
1763 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1764 // also allow array-loading from the primary supertype
1765 // array during subtype checks
1766 Opcode() == Op_LoadKlass,
1767 "Field accesses must be precise" );
1768 // For klass/static loads, we expect the _type to be precise
1769 }
1770
1771 const TypeKlassPtr *tkls = tp->isa_klassptr();
1772 if (tkls != NULL && !StressReflectiveCode) {
1773 ciKlass* klass = tkls->klass();
1774 if (klass->is_loaded() && tkls->klass_is_exact()) {
1775 // We are loading a field from a Klass metaobject whose identity
1776 // is known at compile time (the type is "exact" or "precise").
1777 // Check for fields we know are maintained as constants by the VM.
1778 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1779 // The field is Klass::_super_check_offset. Return its (constant) value.
1780 // (Folds up type checking code.)
1781 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1782 return TypeInt::make(klass->super_check_offset());
1783 }
1784 // Compute index into primary_supers array
1785 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1786 // Check for overflowing; use unsigned compare to handle the negative case.
1787 if( depth < ciKlass::primary_super_limit() ) {
1788 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1789 // (Folds up type checking code.)
1790 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1791 ciKlass *ss = klass->super_of_depth(depth);
1792 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1793 }
1794 const Type* aift = load_array_final_field(tkls, klass);
1795 if (aift != NULL) return aift;
1796 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1797 // The field is Klass::_java_mirror. Return its (constant) value.
1798 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1799 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1800 return TypeInstPtr::make(klass->java_mirror());
1801 }
1802 }
1803
1804 // We can still check if we are loading from the primary_supers array at a
1805 // shallow enough depth. Even though the klass is not exact, entries less
1806 // than or equal to its super depth are correct.
1807 if (klass->is_loaded() ) {
1808 ciType *inner = klass;
1809 while( inner->is_obj_array_klass() )
1810 inner = inner->as_obj_array_klass()->base_element_type();
1811 if( inner->is_instance_klass() &&
1812 !inner->as_instance_klass()->flags().is_interface() ) {
1813 // Compute index into primary_supers array
1814 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1815 // Check for overflowing; use unsigned compare to handle the negative case.
1816 if( depth < ciKlass::primary_super_limit() &&
1817 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1818 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1819 // (Folds up type checking code.)
1820 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1821 ciKlass *ss = klass->super_of_depth(depth);
1822 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1823 }
1824 }
1825 }
1826
1827 // If the type is enough to determine that the thing is not an array,
1828 // we can give the layout_helper a positive interval type.
1829 // This will help short-circuit some reflective code.
1830 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1831 && !klass->is_array_klass() // not directly typed as an array
1832 && !klass->is_interface() // specifically not Serializable & Cloneable
1833 && !klass->is_java_lang_Object() // not the supertype of all T[]
1834 ) {
1835 // Note: When interfaces are reliable, we can narrow the interface
1836 // test to (klass != Serializable && klass != Cloneable).
1837 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1838 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1839 // The key property of this type is that it folds up tests
1840 // for array-ness, since it proves that the layout_helper is positive.
1841 // Thus, a generic value like the basic object layout helper works fine.
1842 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1843 }
1844 }
1845
1846 // If we are loading from a freshly-allocated object, produce a zero,
1847 // if the load is provably beyond the header of the object.
1848 // (Also allow a variable load from a fresh array to produce zero.)
1849 const TypeOopPtr *tinst = tp->isa_oopptr();
1850 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1851 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1852 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1853 Node* value = can_see_stored_value(mem,phase);
1854 if (value != NULL && value->is_Con()) {
1855 assert(value->bottom_type()->higher_equal(_type),"sanity");
1856 return value->bottom_type();
1857 }
1858 }
1859
1860 if (is_instance) {
1861 // If we have an instance type and our memory input is the
1862 // programs's initial memory state, there is no matching store,
1863 // so just return a zero of the appropriate type
1864 Node *mem = in(MemNode::Memory);
1865 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1866 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1867 return Type::get_zero_type(_type->basic_type());
1868 }
1869 }
1870 return _type;
1871 }
1872
1873 //------------------------------match_edge-------------------------------------
1874 // Do we Match on this edge index or not? Match only the address.
1875 uint LoadNode::match_edge(uint idx) const {
1876 return idx == MemNode::Address;
1877 }
1878
1879 //--------------------------LoadBNode::Ideal--------------------------------------
1880 //
1881 // If the previous store is to the same address as this load,
1882 // and the value stored was larger than a byte, replace this load
1883 // with the value stored truncated to a byte. If no truncation is
1884 // needed, the replacement is done in LoadNode::Identity().
1885 //
1886 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1887 Node* mem = in(MemNode::Memory);
1888 Node* value = can_see_stored_value(mem,phase);
1889 if( value && !phase->type(value)->higher_equal( _type ) ) {
1890 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1891 return new RShiftINode(result, phase->intcon(24));
1892 }
1893 // Identity call will handle the case where truncation is not needed.
1894 return LoadNode::Ideal(phase, can_reshape);
1895 }
1896
1897 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1898 Node* mem = in(MemNode::Memory);
1899 Node* value = can_see_stored_value(mem,phase);
1900 if (value != NULL && value->is_Con() &&
1901 !value->bottom_type()->higher_equal(_type)) {
1902 // If the input to the store does not fit with the load's result type,
1903 // it must be truncated. We can't delay until Ideal call since
1904 // a singleton Value is needed for split_thru_phi optimization.
1905 int con = value->get_int();
1906 return TypeInt::make((con << 24) >> 24);
1907 }
1908 return LoadNode::Value(phase);
1909 }
1910
1911 //--------------------------LoadUBNode::Ideal-------------------------------------
1912 //
1913 // If the previous store is to the same address as this load,
1914 // and the value stored was larger than a byte, replace this load
1915 // with the value stored truncated to a byte. If no truncation is
1916 // needed, the replacement is done in LoadNode::Identity().
1917 //
1918 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1919 Node* mem = in(MemNode::Memory);
1920 Node* value = can_see_stored_value(mem, phase);
1921 if (value && !phase->type(value)->higher_equal(_type))
1922 return new AndINode(value, phase->intcon(0xFF));
1923 // Identity call will handle the case where truncation is not needed.
1924 return LoadNode::Ideal(phase, can_reshape);
1925 }
1926
1927 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
1928 Node* mem = in(MemNode::Memory);
1929 Node* value = can_see_stored_value(mem,phase);
1930 if (value != NULL && value->is_Con() &&
1931 !value->bottom_type()->higher_equal(_type)) {
1932 // If the input to the store does not fit with the load's result type,
1933 // it must be truncated. We can't delay until Ideal call since
1934 // a singleton Value is needed for split_thru_phi optimization.
1935 int con = value->get_int();
1936 return TypeInt::make(con & 0xFF);
1937 }
1938 return LoadNode::Value(phase);
1939 }
1940
1941 //--------------------------LoadUSNode::Ideal-------------------------------------
1942 //
1943 // If the previous store is to the same address as this load,
1944 // and the value stored was larger than a char, replace this load
1945 // with the value stored truncated to a char. If no truncation is
1946 // needed, the replacement is done in LoadNode::Identity().
1947 //
1948 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1949 Node* mem = in(MemNode::Memory);
1950 Node* value = can_see_stored_value(mem,phase);
1951 if( value && !phase->type(value)->higher_equal( _type ) )
1952 return new AndINode(value,phase->intcon(0xFFFF));
1953 // Identity call will handle the case where truncation is not needed.
1954 return LoadNode::Ideal(phase, can_reshape);
1955 }
1956
1957 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
1958 Node* mem = in(MemNode::Memory);
1959 Node* value = can_see_stored_value(mem,phase);
1960 if (value != NULL && value->is_Con() &&
1961 !value->bottom_type()->higher_equal(_type)) {
1962 // If the input to the store does not fit with the load's result type,
1963 // it must be truncated. We can't delay until Ideal call since
1964 // a singleton Value is needed for split_thru_phi optimization.
1965 int con = value->get_int();
1966 return TypeInt::make(con & 0xFFFF);
1967 }
1968 return LoadNode::Value(phase);
1969 }
1970
1971 //--------------------------LoadSNode::Ideal--------------------------------------
1972 //
1973 // If the previous store is to the same address as this load,
1974 // and the value stored was larger than a short, replace this load
1975 // with the value stored truncated to a short. If no truncation is
1976 // needed, the replacement is done in LoadNode::Identity().
1977 //
1978 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1979 Node* mem = in(MemNode::Memory);
1980 Node* value = can_see_stored_value(mem,phase);
1981 if( value && !phase->type(value)->higher_equal( _type ) ) {
1982 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
1983 return new RShiftINode(result, phase->intcon(16));
1984 }
1985 // Identity call will handle the case where truncation is not needed.
1986 return LoadNode::Ideal(phase, can_reshape);
1987 }
1988
1989 const Type* LoadSNode::Value(PhaseGVN* phase) const {
1990 Node* mem = in(MemNode::Memory);
1991 Node* value = can_see_stored_value(mem,phase);
1992 if (value != NULL && value->is_Con() &&
1993 !value->bottom_type()->higher_equal(_type)) {
1994 // If the input to the store does not fit with the load's result type,
1995 // it must be truncated. We can't delay until Ideal call since
1996 // a singleton Value is needed for split_thru_phi optimization.
1997 int con = value->get_int();
1998 return TypeInt::make((con << 16) >> 16);
1999 }
2000 return LoadNode::Value(phase);
2001 }
2002
2003 //=============================================================================
2004 //----------------------------LoadKlassNode::make------------------------------
2005 // Polymorphic factory method:
2006 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2007 // sanity check the alias category against the created node type
2008 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2009 assert(adr_type != NULL, "expecting TypeKlassPtr");
2010 #ifdef _LP64
2011 if (adr_type->is_ptr_to_narrowklass()) {
2012 assert(UseCompressedClassPointers, "no compressed klasses");
2013 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2014 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2015 }
2016 #endif
2017 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2018 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2019 }
2020
2021 //------------------------------Value------------------------------------------
2022 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2023 return klass_value_common(phase);
2024 }
2025
2026 // In most cases, LoadKlassNode does not have the control input set. If the control
2027 // input is set, it must not be removed (by LoadNode::Ideal()).
2028 bool LoadKlassNode::can_remove_control() const {
2029 return false;
2030 }
2031
2032 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2033 // Either input is TOP ==> the result is TOP
2034 const Type *t1 = phase->type( in(MemNode::Memory) );
2035 if (t1 == Type::TOP) return Type::TOP;
2036 Node *adr = in(MemNode::Address);
2037 const Type *t2 = phase->type( adr );
2038 if (t2 == Type::TOP) return Type::TOP;
2039 const TypePtr *tp = t2->is_ptr();
2040 if (TypePtr::above_centerline(tp->ptr()) ||
2041 tp->ptr() == TypePtr::Null) return Type::TOP;
2042
2043 // Return a more precise klass, if possible
2044 const TypeInstPtr *tinst = tp->isa_instptr();
2045 if (tinst != NULL) {
2046 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2047 int offset = tinst->offset();
2048 if (ik == phase->C->env()->Class_klass()
2049 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2050 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2051 // We are loading a special hidden field from a Class mirror object,
2052 // the field which points to the VM's Klass metaobject.
2053 ciType* t = tinst->java_mirror_type();
2054 // java_mirror_type returns non-null for compile-time Class constants.
2055 if (t != NULL) {
2056 // constant oop => constant klass
2057 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2058 if (t->is_void()) {
2059 // We cannot create a void array. Since void is a primitive type return null
2060 // klass. Users of this result need to do a null check on the returned klass.
2061 return TypePtr::NULL_PTR;
2062 }
2063 return TypeKlassPtr::make(ciArrayKlass::make(t));
2064 }
2065 if (!t->is_klass()) {
2066 // a primitive Class (e.g., int.class) has NULL for a klass field
2067 return TypePtr::NULL_PTR;
2068 }
2069 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2070 return TypeKlassPtr::make(t->as_klass());
2071 }
2072 // non-constant mirror, so we can't tell what's going on
2073 }
2074 if( !ik->is_loaded() )
2075 return _type; // Bail out if not loaded
2076 if (offset == oopDesc::klass_offset_in_bytes()) {
2077 if (tinst->klass_is_exact()) {
2078 return TypeKlassPtr::make(ik);
2079 }
2080 // See if we can become precise: no subklasses and no interface
2081 // (Note: We need to support verified interfaces.)
2082 if (!ik->is_interface() && !ik->has_subklass()) {
2083 //assert(!UseExactTypes, "this code should be useless with exact types");
2084 // Add a dependence; if any subclass added we need to recompile
2085 if (!ik->is_final()) {
2086 // %%% should use stronger assert_unique_concrete_subtype instead
2087 phase->C->dependencies()->assert_leaf_type(ik);
2088 }
2089 // Return precise klass
2090 return TypeKlassPtr::make(ik);
2091 }
2092
2093 // Return root of possible klass
2094 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2095 }
2096 }
2097
2098 // Check for loading klass from an array
2099 const TypeAryPtr *tary = tp->isa_aryptr();
2100 if( tary != NULL ) {
2101 ciKlass *tary_klass = tary->klass();
2102 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2103 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2104 if (tary->klass_is_exact()) {
2105 return TypeKlassPtr::make(tary_klass);
2106 }
2107 ciArrayKlass *ak = tary->klass()->as_array_klass();
2108 // If the klass is an object array, we defer the question to the
2109 // array component klass.
2110 if( ak->is_obj_array_klass() ) {
2111 assert( ak->is_loaded(), "" );
2112 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2113 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2114 ciInstanceKlass* ik = base_k->as_instance_klass();
2115 // See if we can become precise: no subklasses and no interface
2116 if (!ik->is_interface() && !ik->has_subklass()) {
2117 //assert(!UseExactTypes, "this code should be useless with exact types");
2118 // Add a dependence; if any subclass added we need to recompile
2119 if (!ik->is_final()) {
2120 phase->C->dependencies()->assert_leaf_type(ik);
2121 }
2122 // Return precise array klass
2123 return TypeKlassPtr::make(ak);
2124 }
2125 }
2126 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2127 } else { // Found a type-array?
2128 //assert(!UseExactTypes, "this code should be useless with exact types");
2129 assert( ak->is_type_array_klass(), "" );
2130 return TypeKlassPtr::make(ak); // These are always precise
2131 }
2132 }
2133 }
2134
2135 // Check for loading klass from an array klass
2136 const TypeKlassPtr *tkls = tp->isa_klassptr();
2137 if (tkls != NULL && !StressReflectiveCode) {
2138 ciKlass* klass = tkls->klass();
2139 if( !klass->is_loaded() )
2140 return _type; // Bail out if not loaded
2141 if( klass->is_obj_array_klass() &&
2142 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2143 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2144 // // Always returning precise element type is incorrect,
2145 // // e.g., element type could be object and array may contain strings
2146 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2147
2148 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2149 // according to the element type's subclassing.
2150 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2151 }
2152 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2153 tkls->offset() == in_bytes(Klass::super_offset())) {
2154 ciKlass* sup = klass->as_instance_klass()->super();
2155 // The field is Klass::_super. Return its (constant) value.
2156 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2157 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2158 }
2159 }
2160
2161 // Bailout case
2162 return LoadNode::Value(phase);
2163 }
2164
2165 //------------------------------Identity---------------------------------------
2166 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2167 // Also feed through the klass in Allocate(...klass...)._klass.
2168 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2169 return klass_identity_common(phase);
2170 }
2171
2172 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2173 Node* x = LoadNode::Identity(phase);
2174 if (x != this) return x;
2175
2176 // Take apart the address into an oop and and offset.
2177 // Return 'this' if we cannot.
2178 Node* adr = in(MemNode::Address);
2179 intptr_t offset = 0;
2180 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2181 if (base == NULL) return this;
2182 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2183 if (toop == NULL) return this;
2184
2185 // We can fetch the klass directly through an AllocateNode.
2186 // This works even if the klass is not constant (clone or newArray).
2187 if (offset == oopDesc::klass_offset_in_bytes()) {
2188 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2189 if (allocated_klass != NULL) {
2190 return allocated_klass;
2191 }
2192 }
2193
2194 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2195 // See inline_native_Class_query for occurrences of these patterns.
2196 // Java Example: x.getClass().isAssignableFrom(y)
2197 //
2198 // This improves reflective code, often making the Class
2199 // mirror go completely dead. (Current exception: Class
2200 // mirrors may appear in debug info, but we could clean them out by
2201 // introducing a new debug info operator for Klass*.java_mirror).
2202 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2203 && offset == java_lang_Class::klass_offset_in_bytes()) {
2204 // We are loading a special hidden field from a Class mirror,
2205 // the field which points to its Klass or ArrayKlass metaobject.
2206 if (base->is_Load()) {
2207 Node* adr2 = base->in(MemNode::Address);
2208 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2209 if (tkls != NULL && !tkls->empty()
2210 && (tkls->klass()->is_instance_klass() ||
2211 tkls->klass()->is_array_klass())
2212 && adr2->is_AddP()
2213 ) {
2214 int mirror_field = in_bytes(Klass::java_mirror_offset());
2215 if (tkls->offset() == mirror_field) {
2216 return adr2->in(AddPNode::Base);
2217 }
2218 }
2219 }
2220 }
2221
2222 return this;
2223 }
2224
2225
2226 //------------------------------Value------------------------------------------
2227 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2228 const Type *t = klass_value_common(phase);
2229 if (t == Type::TOP)
2230 return t;
2231
2232 return t->make_narrowklass();
2233 }
2234
2235 //------------------------------Identity---------------------------------------
2236 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2237 // Also feed through the klass in Allocate(...klass...)._klass.
2238 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2239 Node *x = klass_identity_common(phase);
2240
2241 const Type *t = phase->type( x );
2242 if( t == Type::TOP ) return x;
2243 if( t->isa_narrowklass()) return x;
2244 assert (!t->isa_narrowoop(), "no narrow oop here");
2245
2246 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2247 }
2248
2249 //------------------------------Value-----------------------------------------
2250 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2251 // Either input is TOP ==> the result is TOP
2252 const Type *t1 = phase->type( in(MemNode::Memory) );
2253 if( t1 == Type::TOP ) return Type::TOP;
2254 Node *adr = in(MemNode::Address);
2255 const Type *t2 = phase->type( adr );
2256 if( t2 == Type::TOP ) return Type::TOP;
2257 const TypePtr *tp = t2->is_ptr();
2258 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2259 const TypeAryPtr *tap = tp->isa_aryptr();
2260 if( !tap ) return _type;
2261 return tap->size();
2262 }
2263
2264 //-------------------------------Ideal---------------------------------------
2265 // Feed through the length in AllocateArray(...length...)._length.
2266 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2267 Node* p = MemNode::Ideal_common(phase, can_reshape);
2268 if (p) return (p == NodeSentinel) ? NULL : p;
2269
2270 // Take apart the address into an oop and and offset.
2271 // Return 'this' if we cannot.
2272 Node* adr = in(MemNode::Address);
2273 intptr_t offset = 0;
2274 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2275 if (base == NULL) return NULL;
2276 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2277 if (tary == NULL) return NULL;
2278
2279 // We can fetch the length directly through an AllocateArrayNode.
2280 // This works even if the length is not constant (clone or newArray).
2281 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2282 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2283 if (alloc != NULL) {
2284 Node* allocated_length = alloc->Ideal_length();
2285 Node* len = alloc->make_ideal_length(tary, phase);
2286 if (allocated_length != len) {
2287 // New CastII improves on this.
2288 return len;
2289 }
2290 }
2291 }
2292
2293 return NULL;
2294 }
2295
2296 //------------------------------Identity---------------------------------------
2297 // Feed through the length in AllocateArray(...length...)._length.
2298 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2299 Node* x = LoadINode::Identity(phase);
2300 if (x != this) return x;
2301
2302 // Take apart the address into an oop and and offset.
2303 // Return 'this' if we cannot.
2304 Node* adr = in(MemNode::Address);
2305 intptr_t offset = 0;
2306 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2307 if (base == NULL) return this;
2308 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2309 if (tary == NULL) return this;
2310
2311 // We can fetch the length directly through an AllocateArrayNode.
2312 // This works even if the length is not constant (clone or newArray).
2313 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2314 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2315 if (alloc != NULL) {
2316 Node* allocated_length = alloc->Ideal_length();
2317 // Do not allow make_ideal_length to allocate a CastII node.
2318 Node* len = alloc->make_ideal_length(tary, phase, false);
2319 if (allocated_length == len) {
2320 // Return allocated_length only if it would not be improved by a CastII.
2321 return allocated_length;
2322 }
2323 }
2324 }
2325
2326 return this;
2327
2328 }
2329
2330 //=============================================================================
2331 //---------------------------StoreNode::make-----------------------------------
2332 // Polymorphic factory method:
2333 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2334 assert((mo == unordered || mo == release), "unexpected");
2335 Compile* C = gvn.C;
2336 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2337 ctl != NULL, "raw memory operations should have control edge");
2338
2339 switch (bt) {
2340 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2341 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2342 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2343 case T_CHAR:
2344 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2345 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2346 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2347 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2348 case T_METADATA:
2349 case T_ADDRESS:
2350 case T_OBJECT:
2351 #ifdef _LP64
2352 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2353 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2354 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2355 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2356 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2357 adr->bottom_type()->isa_rawptr())) {
2358 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2359 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2360 }
2361 #endif
2362 {
2363 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2364 }
2365 }
2366 ShouldNotReachHere();
2367 return (StoreNode*)NULL;
2368 }
2369
2370 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2371 bool require_atomic = true;
2372 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2373 }
2374
2375 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2376 bool require_atomic = true;
2377 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2378 }
2379
2380
2381 //--------------------------bottom_type----------------------------------------
2382 const Type *StoreNode::bottom_type() const {
2383 return Type::MEMORY;
2384 }
2385
2386 //------------------------------hash-------------------------------------------
2387 uint StoreNode::hash() const {
2388 // unroll addition of interesting fields
2389 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2390
2391 // Since they are not commoned, do not hash them:
2392 return NO_HASH;
2393 }
2394
2395 //------------------------------Ideal------------------------------------------
2396 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2397 // When a store immediately follows a relevant allocation/initialization,
2398 // try to capture it into the initialization, or hoist it above.
2399 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2400 Node* p = MemNode::Ideal_common(phase, can_reshape);
2401 if (p) return (p == NodeSentinel) ? NULL : p;
2402
2403 Node* mem = in(MemNode::Memory);
2404 Node* address = in(MemNode::Address);
2405 // Back-to-back stores to same address? Fold em up. Generally
2406 // unsafe if I have intervening uses... Also disallowed for StoreCM
2407 // since they must follow each StoreP operation. Redundant StoreCMs
2408 // are eliminated just before matching in final_graph_reshape.
2409 {
2410 Node* st = mem;
2411 // If Store 'st' has more than one use, we cannot fold 'st' away.
2412 // For example, 'st' might be the final state at a conditional
2413 // return. Or, 'st' might be used by some node which is live at
2414 // the same time 'st' is live, which might be unschedulable. So,
2415 // require exactly ONE user until such time as we clone 'mem' for
2416 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2417 // true).
2418 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2419 // Looking at a dead closed cycle of memory?
2420 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2421 assert(Opcode() == st->Opcode() ||
2422 st->Opcode() == Op_StoreVector ||
2423 Opcode() == Op_StoreVector ||
2424 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2425 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2426 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2427 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2428
2429 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2430 st->as_Store()->memory_size() <= this->memory_size()) {
2431 Node* use = st->raw_out(0);
2432 phase->igvn_rehash_node_delayed(use);
2433 if (can_reshape) {
2434 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2435 } else {
2436 // It's OK to do this in the parser, since DU info is always accurate,
2437 // and the parser always refers to nodes via SafePointNode maps.
2438 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2439 }
2440 return this;
2441 }
2442 st = st->in(MemNode::Memory);
2443 }
2444 }
2445
2446
2447 // Capture an unaliased, unconditional, simple store into an initializer.
2448 // Or, if it is independent of the allocation, hoist it above the allocation.
2449 if (ReduceFieldZeroing && /*can_reshape &&*/
2450 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2451 InitializeNode* init = mem->in(0)->as_Initialize();
2452 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2453 if (offset > 0) {
2454 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2455 // If the InitializeNode captured me, it made a raw copy of me,
2456 // and I need to disappear.
2457 if (moved != NULL) {
2458 // %%% hack to ensure that Ideal returns a new node:
2459 mem = MergeMemNode::make(mem);
2460 return mem; // fold me away
2461 }
2462 }
2463 }
2464
2465 return NULL; // No further progress
2466 }
2467
2468 //------------------------------Value-----------------------------------------
2469 const Type* StoreNode::Value(PhaseGVN* phase) const {
2470 // Either input is TOP ==> the result is TOP
2471 const Type *t1 = phase->type( in(MemNode::Memory) );
2472 if( t1 == Type::TOP ) return Type::TOP;
2473 const Type *t2 = phase->type( in(MemNode::Address) );
2474 if( t2 == Type::TOP ) return Type::TOP;
2475 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2476 if( t3 == Type::TOP ) return Type::TOP;
2477 return Type::MEMORY;
2478 }
2479
2480 //------------------------------Identity---------------------------------------
2481 // Remove redundant stores:
2482 // Store(m, p, Load(m, p)) changes to m.
2483 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2484 Node* StoreNode::Identity(PhaseGVN* phase) {
2485 Node* mem = in(MemNode::Memory);
2486 Node* adr = in(MemNode::Address);
2487 Node* val = in(MemNode::ValueIn);
2488
2489 // Load then Store? Then the Store is useless
2490 if (val->is_Load() &&
2491 val->in(MemNode::Address)->eqv_uncast(adr) &&
2492 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2493 val->as_Load()->store_Opcode() == Opcode()) {
2494 return mem;
2495 }
2496
2497 // Two stores in a row of the same value?
2498 if (mem->is_Store() &&
2499 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2500 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2501 mem->Opcode() == Opcode()) {
2502 return mem;
2503 }
2504
2505 // Store of zero anywhere into a freshly-allocated object?
2506 // Then the store is useless.
2507 // (It must already have been captured by the InitializeNode.)
2508 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2509 // a newly allocated object is already all-zeroes everywhere
2510 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2511 return mem;
2512 }
2513
2514 // the store may also apply to zero-bits in an earlier object
2515 Node* prev_mem = find_previous_store(phase);
2516 // Steps (a), (b): Walk past independent stores to find an exact match.
2517 if (prev_mem != NULL) {
2518 Node* prev_val = can_see_stored_value(prev_mem, phase);
2519 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2520 // prev_val and val might differ by a cast; it would be good
2521 // to keep the more informative of the two.
2522 return mem;
2523 }
2524 }
2525 }
2526
2527 return this;
2528 }
2529
2530 //------------------------------match_edge-------------------------------------
2531 // Do we Match on this edge index or not? Match only memory & value
2532 uint StoreNode::match_edge(uint idx) const {
2533 return idx == MemNode::Address || idx == MemNode::ValueIn;
2534 }
2535
2536 //------------------------------cmp--------------------------------------------
2537 // Do not common stores up together. They generally have to be split
2538 // back up anyways, so do not bother.
2539 uint StoreNode::cmp( const Node &n ) const {
2540 return (&n == this); // Always fail except on self
2541 }
2542
2543 //------------------------------Ideal_masked_input-----------------------------
2544 // Check for a useless mask before a partial-word store
2545 // (StoreB ... (AndI valIn conIa) )
2546 // If (conIa & mask == mask) this simplifies to
2547 // (StoreB ... (valIn) )
2548 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2549 Node *val = in(MemNode::ValueIn);
2550 if( val->Opcode() == Op_AndI ) {
2551 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2552 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2553 set_req(MemNode::ValueIn, val->in(1));
2554 return this;
2555 }
2556 }
2557 return NULL;
2558 }
2559
2560
2561 //------------------------------Ideal_sign_extended_input----------------------
2562 // Check for useless sign-extension before a partial-word store
2563 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2564 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2565 // (StoreB ... (valIn) )
2566 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2567 Node *val = in(MemNode::ValueIn);
2568 if( val->Opcode() == Op_RShiftI ) {
2569 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2570 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2571 Node *shl = val->in(1);
2572 if( shl->Opcode() == Op_LShiftI ) {
2573 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2574 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2575 set_req(MemNode::ValueIn, shl->in(1));
2576 return this;
2577 }
2578 }
2579 }
2580 }
2581 return NULL;
2582 }
2583
2584 //------------------------------value_never_loaded-----------------------------------
2585 // Determine whether there are any possible loads of the value stored.
2586 // For simplicity, we actually check if there are any loads from the
2587 // address stored to, not just for loads of the value stored by this node.
2588 //
2589 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2590 Node *adr = in(Address);
2591 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2592 if (adr_oop == NULL)
2593 return false;
2594 if (!adr_oop->is_known_instance_field())
2595 return false; // if not a distinct instance, there may be aliases of the address
2596 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2597 Node *use = adr->fast_out(i);
2598 if (use->is_Load() || use->is_LoadStore()) {
2599 return false;
2600 }
2601 }
2602 return true;
2603 }
2604
2605 //=============================================================================
2606 //------------------------------Ideal------------------------------------------
2607 // If the store is from an AND mask that leaves the low bits untouched, then
2608 // we can skip the AND operation. If the store is from a sign-extension
2609 // (a left shift, then right shift) we can skip both.
2610 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2611 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2612 if( progress != NULL ) return progress;
2613
2614 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2615 if( progress != NULL ) return progress;
2616
2617 // Finally check the default case
2618 return StoreNode::Ideal(phase, can_reshape);
2619 }
2620
2621 //=============================================================================
2622 //------------------------------Ideal------------------------------------------
2623 // If the store is from an AND mask that leaves the low bits untouched, then
2624 // we can skip the AND operation
2625 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2626 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2627 if( progress != NULL ) return progress;
2628
2629 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2630 if( progress != NULL ) return progress;
2631
2632 // Finally check the default case
2633 return StoreNode::Ideal(phase, can_reshape);
2634 }
2635
2636 //=============================================================================
2637 //------------------------------Identity---------------------------------------
2638 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2639 // No need to card mark when storing a null ptr
2640 Node* my_store = in(MemNode::OopStore);
2641 if (my_store->is_Store()) {
2642 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2643 if( t1 == TypePtr::NULL_PTR ) {
2644 return in(MemNode::Memory);
2645 }
2646 }
2647 return this;
2648 }
2649
2650 //=============================================================================
2651 //------------------------------Ideal---------------------------------------
2652 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2653 Node* progress = StoreNode::Ideal(phase, can_reshape);
2654 if (progress != NULL) return progress;
2655
2656 Node* my_store = in(MemNode::OopStore);
2657 if (my_store->is_MergeMem()) {
2658 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2659 set_req(MemNode::OopStore, mem);
2660 return this;
2661 }
2662
2663 return NULL;
2664 }
2665
2666 //------------------------------Value-----------------------------------------
2667 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2668 // Either input is TOP ==> the result is TOP
2669 const Type *t = phase->type( in(MemNode::Memory) );
2670 if( t == Type::TOP ) return Type::TOP;
2671 t = phase->type( in(MemNode::Address) );
2672 if( t == Type::TOP ) return Type::TOP;
2673 t = phase->type( in(MemNode::ValueIn) );
2674 if( t == Type::TOP ) return Type::TOP;
2675 // If extra input is TOP ==> the result is TOP
2676 t = phase->type( in(MemNode::OopStore) );
2677 if( t == Type::TOP ) return Type::TOP;
2678
2679 return StoreNode::Value( phase );
2680 }
2681
2682
2683 //=============================================================================
2684 //----------------------------------SCMemProjNode------------------------------
2685 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2686 {
2687 return bottom_type();
2688 }
2689
2690 //=============================================================================
2691 //----------------------------------LoadStoreNode------------------------------
2692 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2693 : Node(required),
2694 _type(rt),
2695 _adr_type(at)
2696 {
2697 init_req(MemNode::Control, c );
2698 init_req(MemNode::Memory , mem);
2699 init_req(MemNode::Address, adr);
2700 init_req(MemNode::ValueIn, val);
2701 init_class_id(Class_LoadStore);
2702 }
2703
2704 uint LoadStoreNode::ideal_reg() const {
2705 return _type->ideal_reg();
2706 }
2707
2708 bool LoadStoreNode::result_not_used() const {
2709 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2710 Node *x = fast_out(i);
2711 if (x->Opcode() == Op_SCMemProj) continue;
2712 return false;
2713 }
2714 return true;
2715 }
2716
2717 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2718
2719 //=============================================================================
2720 //----------------------------------LoadStoreConditionalNode--------------------
2721 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2722 init_req(ExpectedIn, ex );
2723 }
2724
2725 //=============================================================================
2726 //-------------------------------adr_type--------------------------------------
2727 const TypePtr* ClearArrayNode::adr_type() const {
2728 Node *adr = in(3);
2729 if (adr == NULL) return NULL; // node is dead
2730 return MemNode::calculate_adr_type(adr->bottom_type());
2731 }
2732
2733 //------------------------------match_edge-------------------------------------
2734 // Do we Match on this edge index or not? Do not match memory
2735 uint ClearArrayNode::match_edge(uint idx) const {
2736 return idx > 1;
2737 }
2738
2739 //------------------------------Identity---------------------------------------
2740 // Clearing a zero length array does nothing
2741 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2742 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2743 }
2744
2745 //------------------------------Idealize---------------------------------------
2746 // Clearing a short array is faster with stores
2747 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2748 // Already know this is a large node, do not try to ideal it
2749 if (!IdealizeClearArrayNode || _is_large) return NULL;
2750
2751 const int unit = BytesPerLong;
2752 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2753 if (!t) return NULL;
2754 if (!t->is_con()) return NULL;
2755 intptr_t raw_count = t->get_con();
2756 intptr_t size = raw_count;
2757 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2758 // Clearing nothing uses the Identity call.
2759 // Negative clears are possible on dead ClearArrays
2760 // (see jck test stmt114.stmt11402.val).
2761 if (size <= 0 || size % unit != 0) return NULL;
2762 intptr_t count = size / unit;
2763 // Length too long; communicate this to matchers and assemblers.
2764 // Assemblers are responsible to produce fast hardware clears for it.
2765 if (size > InitArrayShortSize) {
2766 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2767 }
2768 Node *mem = in(1);
2769 if( phase->type(mem)==Type::TOP ) return NULL;
2770 Node *adr = in(3);
2771 const Type* at = phase->type(adr);
2772 if( at==Type::TOP ) return NULL;
2773 const TypePtr* atp = at->isa_ptr();
2774 // adjust atp to be the correct array element address type
2775 if (atp == NULL) atp = TypePtr::BOTTOM;
2776 else atp = atp->add_offset(Type::OffsetBot);
2777 // Get base for derived pointer purposes
2778 if( adr->Opcode() != Op_AddP ) Unimplemented();
2779 Node *base = adr->in(1);
2780
2781 Node *zero = phase->makecon(TypeLong::ZERO);
2782 Node *off = phase->MakeConX(BytesPerLong);
2783 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2784 count--;
2785 while( count-- ) {
2786 mem = phase->transform(mem);
2787 adr = phase->transform(new AddPNode(base,adr,off));
2788 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2789 }
2790 return mem;
2791 }
2792
2793 //----------------------------step_through----------------------------------
2794 // Return allocation input memory edge if it is different instance
2795 // or itself if it is the one we are looking for.
2796 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2797 Node* n = *np;
2798 assert(n->is_ClearArray(), "sanity");
2799 intptr_t offset;
2800 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2801 // This method is called only before Allocate nodes are expanded
2802 // during macro nodes expansion. Before that ClearArray nodes are
2803 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2804 // Allocate nodes are expanded) which follows allocations.
2805 assert(alloc != NULL, "should have allocation");
2806 if (alloc->_idx == instance_id) {
2807 // Can not bypass initialization of the instance we are looking for.
2808 return false;
2809 }
2810 // Otherwise skip it.
2811 InitializeNode* init = alloc->initialization();
2812 if (init != NULL)
2813 *np = init->in(TypeFunc::Memory);
2814 else
2815 *np = alloc->in(TypeFunc::Memory);
2816 return true;
2817 }
2818
2819 //----------------------------clear_memory-------------------------------------
2820 // Generate code to initialize object storage to zero.
2821 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2822 intptr_t start_offset,
2823 Node* end_offset,
2824 PhaseGVN* phase) {
2825 intptr_t offset = start_offset;
2826
2827 int unit = BytesPerLong;
2828 if ((offset % unit) != 0) {
2829 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2830 adr = phase->transform(adr);
2831 const TypePtr* atp = TypeRawPtr::BOTTOM;
2832 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2833 mem = phase->transform(mem);
2834 offset += BytesPerInt;
2835 }
2836 assert((offset % unit) == 0, "");
2837
2838 // Initialize the remaining stuff, if any, with a ClearArray.
2839 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2840 }
2841
2842 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2843 Node* start_offset,
2844 Node* end_offset,
2845 PhaseGVN* phase) {
2846 if (start_offset == end_offset) {
2847 // nothing to do
2848 return mem;
2849 }
2850
2851 int unit = BytesPerLong;
2852 Node* zbase = start_offset;
2853 Node* zend = end_offset;
2854
2855 // Scale to the unit required by the CPU:
2856 if (!Matcher::init_array_count_is_in_bytes) {
2857 Node* shift = phase->intcon(exact_log2(unit));
2858 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2859 zend = phase->transform(new URShiftXNode(zend, shift) );
2860 }
2861
2862 // Bulk clear double-words
2863 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2864 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2865 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
2866 return phase->transform(mem);
2867 }
2868
2869 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2870 intptr_t start_offset,
2871 intptr_t end_offset,
2872 PhaseGVN* phase) {
2873 if (start_offset == end_offset) {
2874 // nothing to do
2875 return mem;
2876 }
2877
2878 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2879 intptr_t done_offset = end_offset;
2880 if ((done_offset % BytesPerLong) != 0) {
2881 done_offset -= BytesPerInt;
2882 }
2883 if (done_offset > start_offset) {
2884 mem = clear_memory(ctl, mem, dest,
2885 start_offset, phase->MakeConX(done_offset), phase);
2886 }
2887 if (done_offset < end_offset) { // emit the final 32-bit store
2888 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2889 adr = phase->transform(adr);
2890 const TypePtr* atp = TypeRawPtr::BOTTOM;
2891 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2892 mem = phase->transform(mem);
2893 done_offset += BytesPerInt;
2894 }
2895 assert(done_offset == end_offset, "");
2896 return mem;
2897 }
2898
2899 //=============================================================================
2900 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2901 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2902 _adr_type(C->get_adr_type(alias_idx))
2903 {
2904 init_class_id(Class_MemBar);
2905 Node* top = C->top();
2906 init_req(TypeFunc::I_O,top);
2907 init_req(TypeFunc::FramePtr,top);
2908 init_req(TypeFunc::ReturnAdr,top);
2909 if (precedent != NULL)
2910 init_req(TypeFunc::Parms, precedent);
2911 }
2912
2913 //------------------------------cmp--------------------------------------------
2914 uint MemBarNode::hash() const { return NO_HASH; }
2915 uint MemBarNode::cmp( const Node &n ) const {
2916 return (&n == this); // Always fail except on self
2917 }
2918
2919 //------------------------------make-------------------------------------------
2920 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2921 switch (opcode) {
2922 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2923 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2924 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2925 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2926 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2927 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2928 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2929 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2930 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
2931 case Op_Initialize: return new InitializeNode(C, atp, pn);
2932 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2933 default: ShouldNotReachHere(); return NULL;
2934 }
2935 }
2936
2937 //------------------------------Ideal------------------------------------------
2938 // Return a node which is more "ideal" than the current node. Strip out
2939 // control copies
2940 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2941 if (remove_dead_region(phase, can_reshape)) return this;
2942 // Don't bother trying to transform a dead node
2943 if (in(0) && in(0)->is_top()) {
2944 return NULL;
2945 }
2946
2947 bool progress = false;
2948 // Eliminate volatile MemBars for scalar replaced objects.
2949 if (can_reshape && req() == (Precedent+1)) {
2950 bool eliminate = false;
2951 int opc = Opcode();
2952 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2953 // Volatile field loads and stores.
2954 Node* my_mem = in(MemBarNode::Precedent);
2955 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2956 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2957 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2958 // replace this Precedent (decodeN) with the Load instead.
2959 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2960 Node* load_node = my_mem->in(1);
2961 set_req(MemBarNode::Precedent, load_node);
2962 phase->is_IterGVN()->_worklist.push(my_mem);
2963 my_mem = load_node;
2964 } else {
2965 assert(my_mem->unique_out() == this, "sanity");
2966 del_req(Precedent);
2967 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2968 my_mem = NULL;
2969 }
2970 progress = true;
2971 }
2972 if (my_mem != NULL && my_mem->is_Mem()) {
2973 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2974 // Check for scalar replaced object reference.
2975 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2976 t_oop->offset() != Type::OffsetBot &&
2977 t_oop->offset() != Type::OffsetTop) {
2978 eliminate = true;
2979 }
2980 }
2981 } else if (opc == Op_MemBarRelease) {
2982 // Final field stores.
2983 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2984 if ((alloc != NULL) && alloc->is_Allocate() &&
2985 alloc->as_Allocate()->does_not_escape_thread()) {
2986 // The allocated object does not escape.
2987 eliminate = true;
2988 }
2989 }
2990 if (eliminate) {
2991 // Replace MemBar projections by its inputs.
2992 PhaseIterGVN* igvn = phase->is_IterGVN();
2993 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2994 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2995 // Must return either the original node (now dead) or a new node
2996 // (Do not return a top here, since that would break the uniqueness of top.)
2997 return new ConINode(TypeInt::ZERO);
2998 }
2999 }
3000 return progress ? this : NULL;
3001 }
3002
3003 //------------------------------Value------------------------------------------
3004 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3005 if( !in(0) ) return Type::TOP;
3006 if( phase->type(in(0)) == Type::TOP )
3007 return Type::TOP;
3008 return TypeTuple::MEMBAR;
3009 }
3010
3011 //------------------------------match------------------------------------------
3012 // Construct projections for memory.
3013 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3014 switch (proj->_con) {
3015 case TypeFunc::Control:
3016 case TypeFunc::Memory:
3017 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3018 }
3019 ShouldNotReachHere();
3020 return NULL;
3021 }
3022
3023 //===========================InitializeNode====================================
3024 // SUMMARY:
3025 // This node acts as a memory barrier on raw memory, after some raw stores.
3026 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3027 // The Initialize can 'capture' suitably constrained stores as raw inits.
3028 // It can coalesce related raw stores into larger units (called 'tiles').
3029 // It can avoid zeroing new storage for memory units which have raw inits.
3030 // At macro-expansion, it is marked 'complete', and does not optimize further.
3031 //
3032 // EXAMPLE:
3033 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3034 // ctl = incoming control; mem* = incoming memory
3035 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3036 // First allocate uninitialized memory and fill in the header:
3037 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3038 // ctl := alloc.Control; mem* := alloc.Memory*
3039 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3040 // Then initialize to zero the non-header parts of the raw memory block:
3041 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3042 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3043 // After the initialize node executes, the object is ready for service:
3044 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3045 // Suppose its body is immediately initialized as {1,2}:
3046 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3047 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3048 // mem.SLICE(#short[*]) := store2
3049 //
3050 // DETAILS:
3051 // An InitializeNode collects and isolates object initialization after
3052 // an AllocateNode and before the next possible safepoint. As a
3053 // memory barrier (MemBarNode), it keeps critical stores from drifting
3054 // down past any safepoint or any publication of the allocation.
3055 // Before this barrier, a newly-allocated object may have uninitialized bits.
3056 // After this barrier, it may be treated as a real oop, and GC is allowed.
3057 //
3058 // The semantics of the InitializeNode include an implicit zeroing of
3059 // the new object from object header to the end of the object.
3060 // (The object header and end are determined by the AllocateNode.)
3061 //
3062 // Certain stores may be added as direct inputs to the InitializeNode.
3063 // These stores must update raw memory, and they must be to addresses
3064 // derived from the raw address produced by AllocateNode, and with
3065 // a constant offset. They must be ordered by increasing offset.
3066 // The first one is at in(RawStores), the last at in(req()-1).
3067 // Unlike most memory operations, they are not linked in a chain,
3068 // but are displayed in parallel as users of the rawmem output of
3069 // the allocation.
3070 //
3071 // (See comments in InitializeNode::capture_store, which continue
3072 // the example given above.)
3073 //
3074 // When the associated Allocate is macro-expanded, the InitializeNode
3075 // may be rewritten to optimize collected stores. A ClearArrayNode
3076 // may also be created at that point to represent any required zeroing.
3077 // The InitializeNode is then marked 'complete', prohibiting further
3078 // capturing of nearby memory operations.
3079 //
3080 // During macro-expansion, all captured initializations which store
3081 // constant values of 32 bits or smaller are coalesced (if advantageous)
3082 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3083 // initialized in fewer memory operations. Memory words which are
3084 // covered by neither tiles nor non-constant stores are pre-zeroed
3085 // by explicit stores of zero. (The code shape happens to do all
3086 // zeroing first, then all other stores, with both sequences occurring
3087 // in order of ascending offsets.)
3088 //
3089 // Alternatively, code may be inserted between an AllocateNode and its
3090 // InitializeNode, to perform arbitrary initialization of the new object.
3091 // E.g., the object copying intrinsics insert complex data transfers here.
3092 // The initialization must then be marked as 'complete' disable the
3093 // built-in zeroing semantics and the collection of initializing stores.
3094 //
3095 // While an InitializeNode is incomplete, reads from the memory state
3096 // produced by it are optimizable if they match the control edge and
3097 // new oop address associated with the allocation/initialization.
3098 // They return a stored value (if the offset matches) or else zero.
3099 // A write to the memory state, if it matches control and address,
3100 // and if it is to a constant offset, may be 'captured' by the
3101 // InitializeNode. It is cloned as a raw memory operation and rewired
3102 // inside the initialization, to the raw oop produced by the allocation.
3103 // Operations on addresses which are provably distinct (e.g., to
3104 // other AllocateNodes) are allowed to bypass the initialization.
3105 //
3106 // The effect of all this is to consolidate object initialization
3107 // (both arrays and non-arrays, both piecewise and bulk) into a
3108 // single location, where it can be optimized as a unit.
3109 //
3110 // Only stores with an offset less than TrackedInitializationLimit words
3111 // will be considered for capture by an InitializeNode. This puts a
3112 // reasonable limit on the complexity of optimized initializations.
3113
3114 //---------------------------InitializeNode------------------------------------
3115 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3116 : _is_complete(Incomplete), _does_not_escape(false),
3117 MemBarNode(C, adr_type, rawoop)
3118 {
3119 init_class_id(Class_Initialize);
3120
3121 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3122 assert(in(RawAddress) == rawoop, "proper init");
3123 // Note: allocation() can be NULL, for secondary initialization barriers
3124 }
3125
3126 // Since this node is not matched, it will be processed by the
3127 // register allocator. Declare that there are no constraints
3128 // on the allocation of the RawAddress edge.
3129 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3130 // This edge should be set to top, by the set_complete. But be conservative.
3131 if (idx == InitializeNode::RawAddress)
3132 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3133 return RegMask::Empty;
3134 }
3135
3136 Node* InitializeNode::memory(uint alias_idx) {
3137 Node* mem = in(Memory);
3138 if (mem->is_MergeMem()) {
3139 return mem->as_MergeMem()->memory_at(alias_idx);
3140 } else {
3141 // incoming raw memory is not split
3142 return mem;
3143 }
3144 }
3145
3146 bool InitializeNode::is_non_zero() {
3147 if (is_complete()) return false;
3148 remove_extra_zeroes();
3149 return (req() > RawStores);
3150 }
3151
3152 void InitializeNode::set_complete(PhaseGVN* phase) {
3153 assert(!is_complete(), "caller responsibility");
3154 _is_complete = Complete;
3155
3156 // After this node is complete, it contains a bunch of
3157 // raw-memory initializations. There is no need for
3158 // it to have anything to do with non-raw memory effects.
3159 // Therefore, tell all non-raw users to re-optimize themselves,
3160 // after skipping the memory effects of this initialization.
3161 PhaseIterGVN* igvn = phase->is_IterGVN();
3162 if (igvn) igvn->add_users_to_worklist(this);
3163 }
3164
3165 // convenience function
3166 // return false if the init contains any stores already
3167 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3168 InitializeNode* init = initialization();
3169 if (init == NULL || init->is_complete()) return false;
3170 init->remove_extra_zeroes();
3171 // for now, if this allocation has already collected any inits, bail:
3172 if (init->is_non_zero()) return false;
3173 init->set_complete(phase);
3174 return true;
3175 }
3176
3177 void InitializeNode::remove_extra_zeroes() {
3178 if (req() == RawStores) return;
3179 Node* zmem = zero_memory();
3180 uint fill = RawStores;
3181 for (uint i = fill; i < req(); i++) {
3182 Node* n = in(i);
3183 if (n->is_top() || n == zmem) continue; // skip
3184 if (fill < i) set_req(fill, n); // compact
3185 ++fill;
3186 }
3187 // delete any empty spaces created:
3188 while (fill < req()) {
3189 del_req(fill);
3190 }
3191 }
3192
3193 // Helper for remembering which stores go with which offsets.
3194 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3195 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3196 intptr_t offset = -1;
3197 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3198 phase, offset);
3199 if (base == NULL) return -1; // something is dead,
3200 if (offset < 0) return -1; // dead, dead
3201 return offset;
3202 }
3203
3204 // Helper for proving that an initialization expression is
3205 // "simple enough" to be folded into an object initialization.
3206 // Attempts to prove that a store's initial value 'n' can be captured
3207 // within the initialization without creating a vicious cycle, such as:
3208 // { Foo p = new Foo(); p.next = p; }
3209 // True for constants and parameters and small combinations thereof.
3210 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3211 if (n == NULL) return true; // (can this really happen?)
3212 if (n->is_Proj()) n = n->in(0);
3213 if (n == this) return false; // found a cycle
3214 if (n->is_Con()) return true;
3215 if (n->is_Start()) return true; // params, etc., are OK
3216 if (n->is_Root()) return true; // even better
3217
3218 Node* ctl = n->in(0);
3219 if (ctl != NULL && !ctl->is_top()) {
3220 if (ctl->is_Proj()) ctl = ctl->in(0);
3221 if (ctl == this) return false;
3222
3223 // If we already know that the enclosing memory op is pinned right after
3224 // the init, then any control flow that the store has picked up
3225 // must have preceded the init, or else be equal to the init.
3226 // Even after loop optimizations (which might change control edges)
3227 // a store is never pinned *before* the availability of its inputs.
3228 if (!MemNode::all_controls_dominate(n, this))
3229 return false; // failed to prove a good control
3230 }
3231
3232 // Check data edges for possible dependencies on 'this'.
3233 if ((count += 1) > 20) return false; // complexity limit
3234 for (uint i = 1; i < n->req(); i++) {
3235 Node* m = n->in(i);
3236 if (m == NULL || m == n || m->is_top()) continue;
3237 uint first_i = n->find_edge(m);
3238 if (i != first_i) continue; // process duplicate edge just once
3239 if (!detect_init_independence(m, count)) {
3240 return false;
3241 }
3242 }
3243
3244 return true;
3245 }
3246
3247 // Here are all the checks a Store must pass before it can be moved into
3248 // an initialization. Returns zero if a check fails.
3249 // On success, returns the (constant) offset to which the store applies,
3250 // within the initialized memory.
3251 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3252 const int FAIL = 0;
3253 if (st->is_unaligned_access()) {
3254 return FAIL;
3255 }
3256 if (st->req() != MemNode::ValueIn + 1)
3257 return FAIL; // an inscrutable StoreNode (card mark?)
3258 Node* ctl = st->in(MemNode::Control);
3259 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3260 return FAIL; // must be unconditional after the initialization
3261 Node* mem = st->in(MemNode::Memory);
3262 if (!(mem->is_Proj() && mem->in(0) == this))
3263 return FAIL; // must not be preceded by other stores
3264 Node* adr = st->in(MemNode::Address);
3265 intptr_t offset;
3266 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3267 if (alloc == NULL)
3268 return FAIL; // inscrutable address
3269 if (alloc != allocation())
3270 return FAIL; // wrong allocation! (store needs to float up)
3271 Node* val = st->in(MemNode::ValueIn);
3272 int complexity_count = 0;
3273 if (!detect_init_independence(val, complexity_count))
3274 return FAIL; // stored value must be 'simple enough'
3275
3276 // The Store can be captured only if nothing after the allocation
3277 // and before the Store is using the memory location that the store
3278 // overwrites.
3279 bool failed = false;
3280 // If is_complete_with_arraycopy() is true the shape of the graph is
3281 // well defined and is safe so no need for extra checks.
3282 if (!is_complete_with_arraycopy()) {
3283 // We are going to look at each use of the memory state following
3284 // the allocation to make sure nothing reads the memory that the
3285 // Store writes.
3286 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3287 int alias_idx = phase->C->get_alias_index(t_adr);
3288 ResourceMark rm;
3289 Unique_Node_List mems;
3290 mems.push(mem);
3291 Node* unique_merge = NULL;
3292 for (uint next = 0; next < mems.size(); ++next) {
3293 Node *m = mems.at(next);
3294 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3295 Node *n = m->fast_out(j);
3296 if (n->outcnt() == 0) {
3297 continue;
3298 }
3299 if (n == st) {
3300 continue;
3301 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3302 // If the control of this use is different from the control
3303 // of the Store which is right after the InitializeNode then
3304 // this node cannot be between the InitializeNode and the
3305 // Store.
3306 continue;
3307 } else if (n->is_MergeMem()) {
3308 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3309 // We can hit a MergeMemNode (that will likely go away
3310 // later) that is a direct use of the memory state
3311 // following the InitializeNode on the same slice as the
3312 // store node that we'd like to capture. We need to check
3313 // the uses of the MergeMemNode.
3314 mems.push(n);
3315 }
3316 } else if (n->is_Mem()) {
3317 Node* other_adr = n->in(MemNode::Address);
3318 if (other_adr == adr) {
3319 failed = true;
3320 break;
3321 } else {
3322 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3323 if (other_t_adr != NULL) {
3324 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3325 if (other_alias_idx == alias_idx) {
3326 // A load from the same memory slice as the store right
3327 // after the InitializeNode. We check the control of the
3328 // object/array that is loaded from. If it's the same as
3329 // the store control then we cannot capture the store.
3330 assert(!n->is_Store(), "2 stores to same slice on same control?");
3331 Node* base = other_adr;
3332 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3333 base = base->in(AddPNode::Base);
3334 if (base != NULL) {
3335 base = base->uncast();
3336 if (base->is_Proj() && base->in(0) == alloc) {
3337 failed = true;
3338 break;
3339 }
3340 }
3341 }
3342 }
3343 }
3344 } else {
3345 failed = true;
3346 break;
3347 }
3348 }
3349 }
3350 }
3351 if (failed) {
3352 if (!can_reshape) {
3353 // We decided we couldn't capture the store during parsing. We
3354 // should try again during the next IGVN once the graph is
3355 // cleaner.
3356 phase->C->record_for_igvn(st);
3357 }
3358 return FAIL;
3359 }
3360
3361 return offset; // success
3362 }
3363
3364 // Find the captured store in(i) which corresponds to the range
3365 // [start..start+size) in the initialized object.
3366 // If there is one, return its index i. If there isn't, return the
3367 // negative of the index where it should be inserted.
3368 // Return 0 if the queried range overlaps an initialization boundary
3369 // or if dead code is encountered.
3370 // If size_in_bytes is zero, do not bother with overlap checks.
3371 int InitializeNode::captured_store_insertion_point(intptr_t start,
3372 int size_in_bytes,
3373 PhaseTransform* phase) {
3374 const int FAIL = 0, MAX_STORE = BytesPerLong;
3375
3376 if (is_complete())
3377 return FAIL; // arraycopy got here first; punt
3378
3379 assert(allocation() != NULL, "must be present");
3380
3381 // no negatives, no header fields:
3382 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3383
3384 // after a certain size, we bail out on tracking all the stores:
3385 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3386 if (start >= ti_limit) return FAIL;
3387
3388 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3389 if (i >= limit) return -(int)i; // not found; here is where to put it
3390
3391 Node* st = in(i);
3392 intptr_t st_off = get_store_offset(st, phase);
3393 if (st_off < 0) {
3394 if (st != zero_memory()) {
3395 return FAIL; // bail out if there is dead garbage
3396 }
3397 } else if (st_off > start) {
3398 // ...we are done, since stores are ordered
3399 if (st_off < start + size_in_bytes) {
3400 return FAIL; // the next store overlaps
3401 }
3402 return -(int)i; // not found; here is where to put it
3403 } else if (st_off < start) {
3404 if (size_in_bytes != 0 &&
3405 start < st_off + MAX_STORE &&
3406 start < st_off + st->as_Store()->memory_size()) {
3407 return FAIL; // the previous store overlaps
3408 }
3409 } else {
3410 if (size_in_bytes != 0 &&
3411 st->as_Store()->memory_size() != size_in_bytes) {
3412 return FAIL; // mismatched store size
3413 }
3414 return i;
3415 }
3416
3417 ++i;
3418 }
3419 }
3420
3421 // Look for a captured store which initializes at the offset 'start'
3422 // with the given size. If there is no such store, and no other
3423 // initialization interferes, then return zero_memory (the memory
3424 // projection of the AllocateNode).
3425 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3426 PhaseTransform* phase) {
3427 assert(stores_are_sane(phase), "");
3428 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3429 if (i == 0) {
3430 return NULL; // something is dead
3431 } else if (i < 0) {
3432 return zero_memory(); // just primordial zero bits here
3433 } else {
3434 Node* st = in(i); // here is the store at this position
3435 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3436 return st;
3437 }
3438 }
3439
3440 // Create, as a raw pointer, an address within my new object at 'offset'.
3441 Node* InitializeNode::make_raw_address(intptr_t offset,
3442 PhaseTransform* phase) {
3443 Node* addr = in(RawAddress);
3444 if (offset != 0) {
3445 Compile* C = phase->C;
3446 addr = phase->transform( new AddPNode(C->top(), addr,
3447 phase->MakeConX(offset)) );
3448 }
3449 return addr;
3450 }
3451
3452 // Clone the given store, converting it into a raw store
3453 // initializing a field or element of my new object.
3454 // Caller is responsible for retiring the original store,
3455 // with subsume_node or the like.
3456 //
3457 // From the example above InitializeNode::InitializeNode,
3458 // here are the old stores to be captured:
3459 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3460 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3461 //
3462 // Here is the changed code; note the extra edges on init:
3463 // alloc = (Allocate ...)
3464 // rawoop = alloc.RawAddress
3465 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3466 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3467 // init = (Initialize alloc.Control alloc.Memory rawoop
3468 // rawstore1 rawstore2)
3469 //
3470 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3471 PhaseTransform* phase, bool can_reshape) {
3472 assert(stores_are_sane(phase), "");
3473
3474 if (start < 0) return NULL;
3475 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3476
3477 Compile* C = phase->C;
3478 int size_in_bytes = st->memory_size();
3479 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3480 if (i == 0) return NULL; // bail out
3481 Node* prev_mem = NULL; // raw memory for the captured store
3482 if (i > 0) {
3483 prev_mem = in(i); // there is a pre-existing store under this one
3484 set_req(i, C->top()); // temporarily disconnect it
3485 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3486 } else {
3487 i = -i; // no pre-existing store
3488 prev_mem = zero_memory(); // a slice of the newly allocated object
3489 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3490 set_req(--i, C->top()); // reuse this edge; it has been folded away
3491 else
3492 ins_req(i, C->top()); // build a new edge
3493 }
3494 Node* new_st = st->clone();
3495 new_st->set_req(MemNode::Control, in(Control));
3496 new_st->set_req(MemNode::Memory, prev_mem);
3497 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3498 new_st = phase->transform(new_st);
3499
3500 // At this point, new_st might have swallowed a pre-existing store
3501 // at the same offset, or perhaps new_st might have disappeared,
3502 // if it redundantly stored the same value (or zero to fresh memory).
3503
3504 // In any case, wire it in:
3505 phase->igvn_rehash_node_delayed(this);
3506 set_req(i, new_st);
3507
3508 // The caller may now kill the old guy.
3509 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3510 assert(check_st == new_st || check_st == NULL, "must be findable");
3511 assert(!is_complete(), "");
3512 return new_st;
3513 }
3514
3515 static bool store_constant(jlong* tiles, int num_tiles,
3516 intptr_t st_off, int st_size,
3517 jlong con) {
3518 if ((st_off & (st_size-1)) != 0)
3519 return false; // strange store offset (assume size==2**N)
3520 address addr = (address)tiles + st_off;
3521 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3522 switch (st_size) {
3523 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3524 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3525 case sizeof(jint): *(jint*) addr = (jint) con; break;
3526 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3527 default: return false; // strange store size (detect size!=2**N here)
3528 }
3529 return true; // return success to caller
3530 }
3531
3532 // Coalesce subword constants into int constants and possibly
3533 // into long constants. The goal, if the CPU permits,
3534 // is to initialize the object with a small number of 64-bit tiles.
3535 // Also, convert floating-point constants to bit patterns.
3536 // Non-constants are not relevant to this pass.
3537 //
3538 // In terms of the running example on InitializeNode::InitializeNode
3539 // and InitializeNode::capture_store, here is the transformation
3540 // of rawstore1 and rawstore2 into rawstore12:
3541 // alloc = (Allocate ...)
3542 // rawoop = alloc.RawAddress
3543 // tile12 = 0x00010002
3544 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3545 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3546 //
3547 void
3548 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3549 Node* size_in_bytes,
3550 PhaseGVN* phase) {
3551 Compile* C = phase->C;
3552
3553 assert(stores_are_sane(phase), "");
3554 // Note: After this pass, they are not completely sane,
3555 // since there may be some overlaps.
3556
3557 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3558
3559 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3560 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3561 size_limit = MIN2(size_limit, ti_limit);
3562 size_limit = align_size_up(size_limit, BytesPerLong);
3563 int num_tiles = size_limit / BytesPerLong;
3564
3565 // allocate space for the tile map:
3566 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3567 jlong tiles_buf[small_len];
3568 Node* nodes_buf[small_len];
3569 jlong inits_buf[small_len];
3570 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3571 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3572 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3573 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3574 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3575 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3576 // tiles: exact bitwise model of all primitive constants
3577 // nodes: last constant-storing node subsumed into the tiles model
3578 // inits: which bytes (in each tile) are touched by any initializations
3579
3580 //// Pass A: Fill in the tile model with any relevant stores.
3581
3582 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3583 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3584 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3585 Node* zmem = zero_memory(); // initially zero memory state
3586 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3587 Node* st = in(i);
3588 intptr_t st_off = get_store_offset(st, phase);
3589
3590 // Figure out the store's offset and constant value:
3591 if (st_off < header_size) continue; //skip (ignore header)
3592 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3593 int st_size = st->as_Store()->memory_size();
3594 if (st_off + st_size > size_limit) break;
3595
3596 // Record which bytes are touched, whether by constant or not.
3597 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3598 continue; // skip (strange store size)
3599
3600 const Type* val = phase->type(st->in(MemNode::ValueIn));
3601 if (!val->singleton()) continue; //skip (non-con store)
3602 BasicType type = val->basic_type();
3603
3604 jlong con = 0;
3605 switch (type) {
3606 case T_INT: con = val->is_int()->get_con(); break;
3607 case T_LONG: con = val->is_long()->get_con(); break;
3608 case T_FLOAT: con = jint_cast(val->getf()); break;
3609 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3610 default: continue; //skip (odd store type)
3611 }
3612
3613 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3614 st->Opcode() == Op_StoreL) {
3615 continue; // This StoreL is already optimal.
3616 }
3617
3618 // Store down the constant.
3619 store_constant(tiles, num_tiles, st_off, st_size, con);
3620
3621 intptr_t j = st_off >> LogBytesPerLong;
3622
3623 if (type == T_INT && st_size == BytesPerInt
3624 && (st_off & BytesPerInt) == BytesPerInt) {
3625 jlong lcon = tiles[j];
3626 if (!Matcher::isSimpleConstant64(lcon) &&
3627 st->Opcode() == Op_StoreI) {
3628 // This StoreI is already optimal by itself.
3629 jint* intcon = (jint*) &tiles[j];
3630 intcon[1] = 0; // undo the store_constant()
3631
3632 // If the previous store is also optimal by itself, back up and
3633 // undo the action of the previous loop iteration... if we can.
3634 // But if we can't, just let the previous half take care of itself.
3635 st = nodes[j];
3636 st_off -= BytesPerInt;
3637 con = intcon[0];
3638 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3639 assert(st_off >= header_size, "still ignoring header");
3640 assert(get_store_offset(st, phase) == st_off, "must be");
3641 assert(in(i-1) == zmem, "must be");
3642 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3643 assert(con == tcon->is_int()->get_con(), "must be");
3644 // Undo the effects of the previous loop trip, which swallowed st:
3645 intcon[0] = 0; // undo store_constant()
3646 set_req(i-1, st); // undo set_req(i, zmem)
3647 nodes[j] = NULL; // undo nodes[j] = st
3648 --old_subword; // undo ++old_subword
3649 }
3650 continue; // This StoreI is already optimal.
3651 }
3652 }
3653
3654 // This store is not needed.
3655 set_req(i, zmem);
3656 nodes[j] = st; // record for the moment
3657 if (st_size < BytesPerLong) // something has changed
3658 ++old_subword; // includes int/float, but who's counting...
3659 else ++old_long;
3660 }
3661
3662 if ((old_subword + old_long) == 0)
3663 return; // nothing more to do
3664
3665 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3666 // Be sure to insert them before overlapping non-constant stores.
3667 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3668 for (int j = 0; j < num_tiles; j++) {
3669 jlong con = tiles[j];
3670 jlong init = inits[j];
3671 if (con == 0) continue;
3672 jint con0, con1; // split the constant, address-wise
3673 jint init0, init1; // split the init map, address-wise
3674 { union { jlong con; jint intcon[2]; } u;
3675 u.con = con;
3676 con0 = u.intcon[0];
3677 con1 = u.intcon[1];
3678 u.con = init;
3679 init0 = u.intcon[0];
3680 init1 = u.intcon[1];
3681 }
3682
3683 Node* old = nodes[j];
3684 assert(old != NULL, "need the prior store");
3685 intptr_t offset = (j * BytesPerLong);
3686
3687 bool split = !Matcher::isSimpleConstant64(con);
3688
3689 if (offset < header_size) {
3690 assert(offset + BytesPerInt >= header_size, "second int counts");
3691 assert(*(jint*)&tiles[j] == 0, "junk in header");
3692 split = true; // only the second word counts
3693 // Example: int a[] = { 42 ... }
3694 } else if (con0 == 0 && init0 == -1) {
3695 split = true; // first word is covered by full inits
3696 // Example: int a[] = { ... foo(), 42 ... }
3697 } else if (con1 == 0 && init1 == -1) {
3698 split = true; // second word is covered by full inits
3699 // Example: int a[] = { ... 42, foo() ... }
3700 }
3701
3702 // Here's a case where init0 is neither 0 nor -1:
3703 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3704 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3705 // In this case the tile is not split; it is (jlong)42.
3706 // The big tile is stored down, and then the foo() value is inserted.
3707 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3708
3709 Node* ctl = old->in(MemNode::Control);
3710 Node* adr = make_raw_address(offset, phase);
3711 const TypePtr* atp = TypeRawPtr::BOTTOM;
3712
3713 // One or two coalesced stores to plop down.
3714 Node* st[2];
3715 intptr_t off[2];
3716 int nst = 0;
3717 if (!split) {
3718 ++new_long;
3719 off[nst] = offset;
3720 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3721 phase->longcon(con), T_LONG, MemNode::unordered);
3722 } else {
3723 // Omit either if it is a zero.
3724 if (con0 != 0) {
3725 ++new_int;
3726 off[nst] = offset;
3727 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3728 phase->intcon(con0), T_INT, MemNode::unordered);
3729 }
3730 if (con1 != 0) {
3731 ++new_int;
3732 offset += BytesPerInt;
3733 adr = make_raw_address(offset, phase);
3734 off[nst] = offset;
3735 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3736 phase->intcon(con1), T_INT, MemNode::unordered);
3737 }
3738 }
3739
3740 // Insert second store first, then the first before the second.
3741 // Insert each one just before any overlapping non-constant stores.
3742 while (nst > 0) {
3743 Node* st1 = st[--nst];
3744 C->copy_node_notes_to(st1, old);
3745 st1 = phase->transform(st1);
3746 offset = off[nst];
3747 assert(offset >= header_size, "do not smash header");
3748 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3749 guarantee(ins_idx != 0, "must re-insert constant store");
3750 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3751 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3752 set_req(--ins_idx, st1);
3753 else
3754 ins_req(ins_idx, st1);
3755 }
3756 }
3757
3758 if (PrintCompilation && WizardMode)
3759 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3760 old_subword, old_long, new_int, new_long);
3761 if (C->log() != NULL)
3762 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3763 old_subword, old_long, new_int, new_long);
3764
3765 // Clean up any remaining occurrences of zmem:
3766 remove_extra_zeroes();
3767 }
3768
3769 // Explore forward from in(start) to find the first fully initialized
3770 // word, and return its offset. Skip groups of subword stores which
3771 // together initialize full words. If in(start) is itself part of a
3772 // fully initialized word, return the offset of in(start). If there
3773 // are no following full-word stores, or if something is fishy, return
3774 // a negative value.
3775 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3776 int int_map = 0;
3777 intptr_t int_map_off = 0;
3778 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3779
3780 for (uint i = start, limit = req(); i < limit; i++) {
3781 Node* st = in(i);
3782
3783 intptr_t st_off = get_store_offset(st, phase);
3784 if (st_off < 0) break; // return conservative answer
3785
3786 int st_size = st->as_Store()->memory_size();
3787 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3788 return st_off; // we found a complete word init
3789 }
3790
3791 // update the map:
3792
3793 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3794 if (this_int_off != int_map_off) {
3795 // reset the map:
3796 int_map = 0;
3797 int_map_off = this_int_off;
3798 }
3799
3800 int subword_off = st_off - this_int_off;
3801 int_map |= right_n_bits(st_size) << subword_off;
3802 if ((int_map & FULL_MAP) == FULL_MAP) {
3803 return this_int_off; // we found a complete word init
3804 }
3805
3806 // Did this store hit or cross the word boundary?
3807 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3808 if (next_int_off == this_int_off + BytesPerInt) {
3809 // We passed the current int, without fully initializing it.
3810 int_map_off = next_int_off;
3811 int_map >>= BytesPerInt;
3812 } else if (next_int_off > this_int_off + BytesPerInt) {
3813 // We passed the current and next int.
3814 return this_int_off + BytesPerInt;
3815 }
3816 }
3817
3818 return -1;
3819 }
3820
3821
3822 // Called when the associated AllocateNode is expanded into CFG.
3823 // At this point, we may perform additional optimizations.
3824 // Linearize the stores by ascending offset, to make memory
3825 // activity as coherent as possible.
3826 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3827 intptr_t header_size,
3828 Node* size_in_bytes,
3829 PhaseGVN* phase) {
3830 assert(!is_complete(), "not already complete");
3831 assert(stores_are_sane(phase), "");
3832 assert(allocation() != NULL, "must be present");
3833
3834 remove_extra_zeroes();
3835
3836 if (ReduceFieldZeroing || ReduceBulkZeroing)
3837 // reduce instruction count for common initialization patterns
3838 coalesce_subword_stores(header_size, size_in_bytes, phase);
3839
3840 Node* zmem = zero_memory(); // initially zero memory state
3841 Node* inits = zmem; // accumulating a linearized chain of inits
3842 #ifdef ASSERT
3843 intptr_t first_offset = allocation()->minimum_header_size();
3844 intptr_t last_init_off = first_offset; // previous init offset
3845 intptr_t last_init_end = first_offset; // previous init offset+size
3846 intptr_t last_tile_end = first_offset; // previous tile offset+size
3847 #endif
3848 intptr_t zeroes_done = header_size;
3849
3850 bool do_zeroing = true; // we might give up if inits are very sparse
3851 int big_init_gaps = 0; // how many large gaps have we seen?
3852
3853 if (UseTLAB && ZeroTLAB) do_zeroing = false;
3854 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3855
3856 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3857 Node* st = in(i);
3858 intptr_t st_off = get_store_offset(st, phase);
3859 if (st_off < 0)
3860 break; // unknown junk in the inits
3861 if (st->in(MemNode::Memory) != zmem)
3862 break; // complicated store chains somehow in list
3863
3864 int st_size = st->as_Store()->memory_size();
3865 intptr_t next_init_off = st_off + st_size;
3866
3867 if (do_zeroing && zeroes_done < next_init_off) {
3868 // See if this store needs a zero before it or under it.
3869 intptr_t zeroes_needed = st_off;
3870
3871 if (st_size < BytesPerInt) {
3872 // Look for subword stores which only partially initialize words.
3873 // If we find some, we must lay down some word-level zeroes first,
3874 // underneath the subword stores.
3875 //
3876 // Examples:
3877 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3878 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3879 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3880 //
3881 // Note: coalesce_subword_stores may have already done this,
3882 // if it was prompted by constant non-zero subword initializers.
3883 // But this case can still arise with non-constant stores.
3884
3885 intptr_t next_full_store = find_next_fullword_store(i, phase);
3886
3887 // In the examples above:
3888 // in(i) p q r s x y z
3889 // st_off 12 13 14 15 12 13 14
3890 // st_size 1 1 1 1 1 1 1
3891 // next_full_s. 12 16 16 16 16 16 16
3892 // z's_done 12 16 16 16 12 16 12
3893 // z's_needed 12 16 16 16 16 16 16
3894 // zsize 0 0 0 0 4 0 4
3895 if (next_full_store < 0) {
3896 // Conservative tack: Zero to end of current word.
3897 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3898 } else {
3899 // Zero to beginning of next fully initialized word.
3900 // Or, don't zero at all, if we are already in that word.
3901 assert(next_full_store >= zeroes_needed, "must go forward");
3902 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3903 zeroes_needed = next_full_store;
3904 }
3905 }
3906
3907 if (zeroes_needed > zeroes_done) {
3908 intptr_t zsize = zeroes_needed - zeroes_done;
3909 // Do some incremental zeroing on rawmem, in parallel with inits.
3910 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3911 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3912 zeroes_done, zeroes_needed,
3913 phase);
3914 zeroes_done = zeroes_needed;
3915 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
3916 do_zeroing = false; // leave the hole, next time
3917 }
3918 }
3919
3920 // Collect the store and move on:
3921 st->set_req(MemNode::Memory, inits);
3922 inits = st; // put it on the linearized chain
3923 set_req(i, zmem); // unhook from previous position
3924
3925 if (zeroes_done == st_off)
3926 zeroes_done = next_init_off;
3927
3928 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3929
3930 #ifdef ASSERT
3931 // Various order invariants. Weaker than stores_are_sane because
3932 // a large constant tile can be filled in by smaller non-constant stores.
3933 assert(st_off >= last_init_off, "inits do not reverse");
3934 last_init_off = st_off;
3935 const Type* val = NULL;
3936 if (st_size >= BytesPerInt &&
3937 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3938 (int)val->basic_type() < (int)T_OBJECT) {
3939 assert(st_off >= last_tile_end, "tiles do not overlap");
3940 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3941 last_tile_end = MAX2(last_tile_end, next_init_off);
3942 } else {
3943 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3944 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3945 assert(st_off >= last_init_end, "inits do not overlap");
3946 last_init_end = next_init_off; // it's a non-tile
3947 }
3948 #endif //ASSERT
3949 }
3950
3951 remove_extra_zeroes(); // clear out all the zmems left over
3952 add_req(inits);
3953
3954 if (!(UseTLAB && ZeroTLAB)) {
3955 // If anything remains to be zeroed, zero it all now.
3956 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3957 // if it is the last unused 4 bytes of an instance, forget about it
3958 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3959 if (zeroes_done + BytesPerLong >= size_limit) {
3960 AllocateNode* alloc = allocation();
3961 assert(alloc != NULL, "must be present");
3962 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
3963 Node* klass_node = alloc->in(AllocateNode::KlassNode);
3964 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3965 if (zeroes_done == k->layout_helper())
3966 zeroes_done = size_limit;
3967 }
3968 }
3969 if (zeroes_done < size_limit) {
3970 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3971 zeroes_done, size_in_bytes, phase);
3972 }
3973 }
3974
3975 set_complete(phase);
3976 return rawmem;
3977 }
3978
3979
3980 #ifdef ASSERT
3981 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3982 if (is_complete())
3983 return true; // stores could be anything at this point
3984 assert(allocation() != NULL, "must be present");
3985 intptr_t last_off = allocation()->minimum_header_size();
3986 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3987 Node* st = in(i);
3988 intptr_t st_off = get_store_offset(st, phase);
3989 if (st_off < 0) continue; // ignore dead garbage
3990 if (last_off > st_off) {
3991 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3992 this->dump(2);
3993 assert(false, "ascending store offsets");
3994 return false;
3995 }
3996 last_off = st_off + st->as_Store()->memory_size();
3997 }
3998 return true;
3999 }
4000 #endif //ASSERT
4001
4002
4003
4004
4005 //============================MergeMemNode=====================================
4006 //
4007 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4008 // contributing store or call operations. Each contributor provides the memory
4009 // state for a particular "alias type" (see Compile::alias_type). For example,
4010 // if a MergeMem has an input X for alias category #6, then any memory reference
4011 // to alias category #6 may use X as its memory state input, as an exact equivalent
4012 // to using the MergeMem as a whole.
4013 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4014 //
4015 // (Here, the <N> notation gives the index of the relevant adr_type.)
4016 //
4017 // In one special case (and more cases in the future), alias categories overlap.
4018 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4019 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4020 // it is exactly equivalent to that state W:
4021 // MergeMem(<Bot>: W) <==> W
4022 //
4023 // Usually, the merge has more than one input. In that case, where inputs
4024 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4025 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4026 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4027 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4028 //
4029 // A merge can take a "wide" memory state as one of its narrow inputs.
4030 // This simply means that the merge observes out only the relevant parts of
4031 // the wide input. That is, wide memory states arriving at narrow merge inputs
4032 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4033 //
4034 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4035 // and that memory slices "leak through":
4036 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4037 //
4038 // But, in such a cascade, repeated memory slices can "block the leak":
4039 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4040 //
4041 // In the last example, Y is not part of the combined memory state of the
4042 // outermost MergeMem. The system must, of course, prevent unschedulable
4043 // memory states from arising, so you can be sure that the state Y is somehow
4044 // a precursor to state Y'.
4045 //
4046 //
4047 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4048 // of each MergeMemNode array are exactly the numerical alias indexes, including
4049 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4050 // Compile::alias_type (and kin) produce and manage these indexes.
4051 //
4052 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4053 // (Note that this provides quick access to the top node inside MergeMem methods,
4054 // without the need to reach out via TLS to Compile::current.)
4055 //
4056 // As a consequence of what was just described, a MergeMem that represents a full
4057 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4058 // containing all alias categories.
4059 //
4060 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4061 //
4062 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4063 // a memory state for the alias type <N>, or else the top node, meaning that
4064 // there is no particular input for that alias type. Note that the length of
4065 // a MergeMem is variable, and may be extended at any time to accommodate new
4066 // memory states at larger alias indexes. When merges grow, they are of course
4067 // filled with "top" in the unused in() positions.
4068 //
4069 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4070 // (Top was chosen because it works smoothly with passes like GCM.)
4071 //
4072 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4073 // the type of random VM bits like TLS references.) Since it is always the
4074 // first non-Bot memory slice, some low-level loops use it to initialize an
4075 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4076 //
4077 //
4078 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4079 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4080 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4081 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4082 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4083 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4084 //
4085 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4086 // really that different from the other memory inputs. An abbreviation called
4087 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4088 //
4089 //
4090 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4091 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4092 // that "emerges though" the base memory will be marked as excluding the alias types
4093 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4094 //
4095 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4096 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4097 //
4098 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4099 // (It is currently unimplemented.) As you can see, the resulting merge is
4100 // actually a disjoint union of memory states, rather than an overlay.
4101 //
4102
4103 //------------------------------MergeMemNode-----------------------------------
4104 Node* MergeMemNode::make_empty_memory() {
4105 Node* empty_memory = (Node*) Compile::current()->top();
4106 assert(empty_memory->is_top(), "correct sentinel identity");
4107 return empty_memory;
4108 }
4109
4110 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4111 init_class_id(Class_MergeMem);
4112 // all inputs are nullified in Node::Node(int)
4113 // set_input(0, NULL); // no control input
4114
4115 // Initialize the edges uniformly to top, for starters.
4116 Node* empty_mem = make_empty_memory();
4117 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4118 init_req(i,empty_mem);
4119 }
4120 assert(empty_memory() == empty_mem, "");
4121
4122 if( new_base != NULL && new_base->is_MergeMem() ) {
4123 MergeMemNode* mdef = new_base->as_MergeMem();
4124 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4125 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4126 mms.set_memory(mms.memory2());
4127 }
4128 assert(base_memory() == mdef->base_memory(), "");
4129 } else {
4130 set_base_memory(new_base);
4131 }
4132 }
4133
4134 // Make a new, untransformed MergeMem with the same base as 'mem'.
4135 // If mem is itself a MergeMem, populate the result with the same edges.
4136 MergeMemNode* MergeMemNode::make(Node* mem) {
4137 return new MergeMemNode(mem);
4138 }
4139
4140 //------------------------------cmp--------------------------------------------
4141 uint MergeMemNode::hash() const { return NO_HASH; }
4142 uint MergeMemNode::cmp( const Node &n ) const {
4143 return (&n == this); // Always fail except on self
4144 }
4145
4146 //------------------------------Identity---------------------------------------
4147 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4148 // Identity if this merge point does not record any interesting memory
4149 // disambiguations.
4150 Node* base_mem = base_memory();
4151 Node* empty_mem = empty_memory();
4152 if (base_mem != empty_mem) { // Memory path is not dead?
4153 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4154 Node* mem = in(i);
4155 if (mem != empty_mem && mem != base_mem) {
4156 return this; // Many memory splits; no change
4157 }
4158 }
4159 }
4160 return base_mem; // No memory splits; ID on the one true input
4161 }
4162
4163 //------------------------------Ideal------------------------------------------
4164 // This method is invoked recursively on chains of MergeMem nodes
4165 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4166 // Remove chain'd MergeMems
4167 //
4168 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4169 // relative to the "in(Bot)". Since we are patching both at the same time,
4170 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4171 // but rewrite each "in(i)" relative to the new "in(Bot)".
4172 Node *progress = NULL;
4173
4174
4175 Node* old_base = base_memory();
4176 Node* empty_mem = empty_memory();
4177 if (old_base == empty_mem)
4178 return NULL; // Dead memory path.
4179
4180 MergeMemNode* old_mbase;
4181 if (old_base != NULL && old_base->is_MergeMem())
4182 old_mbase = old_base->as_MergeMem();
4183 else
4184 old_mbase = NULL;
4185 Node* new_base = old_base;
4186
4187 // simplify stacked MergeMems in base memory
4188 if (old_mbase) new_base = old_mbase->base_memory();
4189
4190 // the base memory might contribute new slices beyond my req()
4191 if (old_mbase) grow_to_match(old_mbase);
4192
4193 // Look carefully at the base node if it is a phi.
4194 PhiNode* phi_base;
4195 if (new_base != NULL && new_base->is_Phi())
4196 phi_base = new_base->as_Phi();
4197 else
4198 phi_base = NULL;
4199
4200 Node* phi_reg = NULL;
4201 uint phi_len = (uint)-1;
4202 if (phi_base != NULL && !phi_base->is_copy()) {
4203 // do not examine phi if degraded to a copy
4204 phi_reg = phi_base->region();
4205 phi_len = phi_base->req();
4206 // see if the phi is unfinished
4207 for (uint i = 1; i < phi_len; i++) {
4208 if (phi_base->in(i) == NULL) {
4209 // incomplete phi; do not look at it yet!
4210 phi_reg = NULL;
4211 phi_len = (uint)-1;
4212 break;
4213 }
4214 }
4215 }
4216
4217 // Note: We do not call verify_sparse on entry, because inputs
4218 // can normalize to the base_memory via subsume_node or similar
4219 // mechanisms. This method repairs that damage.
4220
4221 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4222
4223 // Look at each slice.
4224 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4225 Node* old_in = in(i);
4226 // calculate the old memory value
4227 Node* old_mem = old_in;
4228 if (old_mem == empty_mem) old_mem = old_base;
4229 assert(old_mem == memory_at(i), "");
4230
4231 // maybe update (reslice) the old memory value
4232
4233 // simplify stacked MergeMems
4234 Node* new_mem = old_mem;
4235 MergeMemNode* old_mmem;
4236 if (old_mem != NULL && old_mem->is_MergeMem())
4237 old_mmem = old_mem->as_MergeMem();
4238 else
4239 old_mmem = NULL;
4240 if (old_mmem == this) {
4241 // This can happen if loops break up and safepoints disappear.
4242 // A merge of BotPtr (default) with a RawPtr memory derived from a
4243 // safepoint can be rewritten to a merge of the same BotPtr with
4244 // the BotPtr phi coming into the loop. If that phi disappears
4245 // also, we can end up with a self-loop of the mergemem.
4246 // In general, if loops degenerate and memory effects disappear,
4247 // a mergemem can be left looking at itself. This simply means
4248 // that the mergemem's default should be used, since there is
4249 // no longer any apparent effect on this slice.
4250 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4251 // from start. Update the input to TOP.
4252 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4253 }
4254 else if (old_mmem != NULL) {
4255 new_mem = old_mmem->memory_at(i);
4256 }
4257 // else preceding memory was not a MergeMem
4258
4259 // replace equivalent phis (unfortunately, they do not GVN together)
4260 if (new_mem != NULL && new_mem != new_base &&
4261 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4262 if (new_mem->is_Phi()) {
4263 PhiNode* phi_mem = new_mem->as_Phi();
4264 for (uint i = 1; i < phi_len; i++) {
4265 if (phi_base->in(i) != phi_mem->in(i)) {
4266 phi_mem = NULL;
4267 break;
4268 }
4269 }
4270 if (phi_mem != NULL) {
4271 // equivalent phi nodes; revert to the def
4272 new_mem = new_base;
4273 }
4274 }
4275 }
4276
4277 // maybe store down a new value
4278 Node* new_in = new_mem;
4279 if (new_in == new_base) new_in = empty_mem;
4280
4281 if (new_in != old_in) {
4282 // Warning: Do not combine this "if" with the previous "if"
4283 // A memory slice might have be be rewritten even if it is semantically
4284 // unchanged, if the base_memory value has changed.
4285 set_req(i, new_in);
4286 progress = this; // Report progress
4287 }
4288 }
4289
4290 if (new_base != old_base) {
4291 set_req(Compile::AliasIdxBot, new_base);
4292 // Don't use set_base_memory(new_base), because we need to update du.
4293 assert(base_memory() == new_base, "");
4294 progress = this;
4295 }
4296
4297 if( base_memory() == this ) {
4298 // a self cycle indicates this memory path is dead
4299 set_req(Compile::AliasIdxBot, empty_mem);
4300 }
4301
4302 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4303 // Recursion must occur after the self cycle check above
4304 if( base_memory()->is_MergeMem() ) {
4305 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4306 Node *m = phase->transform(new_mbase); // Rollup any cycles
4307 if( m != NULL && (m->is_top() ||
4308 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4309 // propagate rollup of dead cycle to self
4310 set_req(Compile::AliasIdxBot, empty_mem);
4311 }
4312 }
4313
4314 if( base_memory() == empty_mem ) {
4315 progress = this;
4316 // Cut inputs during Parse phase only.
4317 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4318 if( !can_reshape ) {
4319 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4320 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4321 }
4322 }
4323 }
4324
4325 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4326 // Check if PhiNode::Ideal's "Split phis through memory merges"
4327 // transform should be attempted. Look for this->phi->this cycle.
4328 uint merge_width = req();
4329 if (merge_width > Compile::AliasIdxRaw) {
4330 PhiNode* phi = base_memory()->as_Phi();
4331 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4332 if (phi->in(i) == this) {
4333 phase->is_IterGVN()->_worklist.push(phi);
4334 break;
4335 }
4336 }
4337 }
4338 }
4339
4340 assert(progress || verify_sparse(), "please, no dups of base");
4341 return progress;
4342 }
4343
4344 //-------------------------set_base_memory-------------------------------------
4345 void MergeMemNode::set_base_memory(Node *new_base) {
4346 Node* empty_mem = empty_memory();
4347 set_req(Compile::AliasIdxBot, new_base);
4348 assert(memory_at(req()) == new_base, "must set default memory");
4349 // Clear out other occurrences of new_base:
4350 if (new_base != empty_mem) {
4351 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4352 if (in(i) == new_base) set_req(i, empty_mem);
4353 }
4354 }
4355 }
4356
4357 //------------------------------out_RegMask------------------------------------
4358 const RegMask &MergeMemNode::out_RegMask() const {
4359 return RegMask::Empty;
4360 }
4361
4362 //------------------------------dump_spec--------------------------------------
4363 #ifndef PRODUCT
4364 void MergeMemNode::dump_spec(outputStream *st) const {
4365 st->print(" {");
4366 Node* base_mem = base_memory();
4367 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4368 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4369 if (mem == base_mem) { st->print(" -"); continue; }
4370 st->print( " N%d:", mem->_idx );
4371 Compile::current()->get_adr_type(i)->dump_on(st);
4372 }
4373 st->print(" }");
4374 }
4375 #endif // !PRODUCT
4376
4377
4378 #ifdef ASSERT
4379 static bool might_be_same(Node* a, Node* b) {
4380 if (a == b) return true;
4381 if (!(a->is_Phi() || b->is_Phi())) return false;
4382 // phis shift around during optimization
4383 return true; // pretty stupid...
4384 }
4385
4386 // verify a narrow slice (either incoming or outgoing)
4387 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4388 if (!VerifyAliases) return; // don't bother to verify unless requested
4389 if (is_error_reported()) return; // muzzle asserts when debugging an error
4390 if (Node::in_dump()) return; // muzzle asserts when printing
4391 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4392 assert(n != NULL, "");
4393 // Elide intervening MergeMem's
4394 while (n->is_MergeMem()) {
4395 n = n->as_MergeMem()->memory_at(alias_idx);
4396 }
4397 Compile* C = Compile::current();
4398 const TypePtr* n_adr_type = n->adr_type();
4399 if (n == m->empty_memory()) {
4400 // Implicit copy of base_memory()
4401 } else if (n_adr_type != TypePtr::BOTTOM) {
4402 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4403 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4404 } else {
4405 // A few places like make_runtime_call "know" that VM calls are narrow,
4406 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4407 bool expected_wide_mem = false;
4408 if (n == m->base_memory()) {
4409 expected_wide_mem = true;
4410 } else if (alias_idx == Compile::AliasIdxRaw ||
4411 n == m->memory_at(Compile::AliasIdxRaw)) {
4412 expected_wide_mem = true;
4413 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4414 // memory can "leak through" calls on channels that
4415 // are write-once. Allow this also.
4416 expected_wide_mem = true;
4417 }
4418 assert(expected_wide_mem, "expected narrow slice replacement");
4419 }
4420 }
4421 #else // !ASSERT
4422 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4423 #endif
4424
4425
4426 //-----------------------------memory_at---------------------------------------
4427 Node* MergeMemNode::memory_at(uint alias_idx) const {
4428 assert(alias_idx >= Compile::AliasIdxRaw ||
4429 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4430 "must avoid base_memory and AliasIdxTop");
4431
4432 // Otherwise, it is a narrow slice.
4433 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4434 Compile *C = Compile::current();
4435 if (is_empty_memory(n)) {
4436 // the array is sparse; empty slots are the "top" node
4437 n = base_memory();
4438 assert(Node::in_dump()
4439 || n == NULL || n->bottom_type() == Type::TOP
4440 || n->adr_type() == NULL // address is TOP
4441 || n->adr_type() == TypePtr::BOTTOM
4442 || n->adr_type() == TypeRawPtr::BOTTOM
4443 || Compile::current()->AliasLevel() == 0,
4444 "must be a wide memory");
4445 // AliasLevel == 0 if we are organizing the memory states manually.
4446 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4447 } else {
4448 // make sure the stored slice is sane
4449 #ifdef ASSERT
4450 if (is_error_reported() || Node::in_dump()) {
4451 } else if (might_be_same(n, base_memory())) {
4452 // Give it a pass: It is a mostly harmless repetition of the base.
4453 // This can arise normally from node subsumption during optimization.
4454 } else {
4455 verify_memory_slice(this, alias_idx, n);
4456 }
4457 #endif
4458 }
4459 return n;
4460 }
4461
4462 //---------------------------set_memory_at-------------------------------------
4463 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4464 verify_memory_slice(this, alias_idx, n);
4465 Node* empty_mem = empty_memory();
4466 if (n == base_memory()) n = empty_mem; // collapse default
4467 uint need_req = alias_idx+1;
4468 if (req() < need_req) {
4469 if (n == empty_mem) return; // already the default, so do not grow me
4470 // grow the sparse array
4471 do {
4472 add_req(empty_mem);
4473 } while (req() < need_req);
4474 }
4475 set_req( alias_idx, n );
4476 }
4477
4478
4479
4480 //--------------------------iteration_setup------------------------------------
4481 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4482 if (other != NULL) {
4483 grow_to_match(other);
4484 // invariant: the finite support of mm2 is within mm->req()
4485 #ifdef ASSERT
4486 for (uint i = req(); i < other->req(); i++) {
4487 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4488 }
4489 #endif
4490 }
4491 // Replace spurious copies of base_memory by top.
4492 Node* base_mem = base_memory();
4493 if (base_mem != NULL && !base_mem->is_top()) {
4494 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4495 if (in(i) == base_mem)
4496 set_req(i, empty_memory());
4497 }
4498 }
4499 }
4500
4501 //---------------------------grow_to_match-------------------------------------
4502 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4503 Node* empty_mem = empty_memory();
4504 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4505 // look for the finite support of the other memory
4506 for (uint i = other->req(); --i >= req(); ) {
4507 if (other->in(i) != empty_mem) {
4508 uint new_len = i+1;
4509 while (req() < new_len) add_req(empty_mem);
4510 break;
4511 }
4512 }
4513 }
4514
4515 //---------------------------verify_sparse-------------------------------------
4516 #ifndef PRODUCT
4517 bool MergeMemNode::verify_sparse() const {
4518 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4519 Node* base_mem = base_memory();
4520 // The following can happen in degenerate cases, since empty==top.
4521 if (is_empty_memory(base_mem)) return true;
4522 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4523 assert(in(i) != NULL, "sane slice");
4524 if (in(i) == base_mem) return false; // should have been the sentinel value!
4525 }
4526 return true;
4527 }
4528
4529 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4530 Node* n;
4531 n = mm->in(idx);
4532 if (mem == n) return true; // might be empty_memory()
4533 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4534 if (mem == n) return true;
4535 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4536 if (mem == n) return true;
4537 if (n == NULL) break;
4538 }
4539 return false;
4540 }
4541 #endif // !PRODUCT