1 /*
2 * Copyright (c) 1997, 2017, 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 default:
823 // ShouldNotReachHere(); ???
824 break;
825 }
826 assert(load != NULL, "LoadNode should have been created");
827 if (unaligned) {
828 load->set_unaligned_access();
829 }
830 if (mismatched) {
831 load->set_mismatched_access();
832 }
833 if (load->Opcode() == Op_LoadN) {
834 Node* ld = gvn.transform(load);
835 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
836 }
837
838 return load;
839 }
840
841 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
842 ControlDependency control_dependency, bool unaligned, bool mismatched) {
843 bool require_atomic = true;
844 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
845 if (unaligned) {
846 load->set_unaligned_access();
847 }
848 if (mismatched) {
849 load->set_mismatched_access();
850 }
851 return load;
852 }
853
854 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
855 ControlDependency control_dependency, bool unaligned, bool mismatched) {
856 bool require_atomic = true;
857 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
858 if (unaligned) {
859 load->set_unaligned_access();
860 }
861 if (mismatched) {
862 load->set_mismatched_access();
863 }
864 return load;
865 }
866
867
868
869 //------------------------------hash-------------------------------------------
870 uint LoadNode::hash() const {
871 // unroll addition of interesting fields
872 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
873 }
874
875 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
876 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
877 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
878 bool is_stable_ary = FoldStableValues &&
879 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
880 tp->isa_aryptr()->is_stable();
881
882 return (eliminate_boxing && non_volatile) || is_stable_ary;
883 }
884
885 return false;
886 }
887
888 // Is the value loaded previously stored by an arraycopy? If so return
889 // a load node that reads from the source array so we may be able to
890 // optimize out the ArrayCopy node later.
891 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const {
892 Node* ld_adr = in(MemNode::Address);
893 intptr_t ld_off = 0;
894 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
895 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
896 if (ac != NULL) {
897 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
898
899 Node* ld = clone();
900 if (ac->as_ArrayCopy()->is_clonebasic()) {
901 assert(ld_alloc != NULL, "need an alloc");
902 Node* addp = in(MemNode::Address)->clone();
903 assert(addp->is_AddP(), "address must be addp");
904 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
905 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
906 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base));
907 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address));
908 ld->set_req(MemNode::Address, phase->transform(addp));
909 if (in(0) != NULL) {
910 assert(ld_alloc->in(0) != NULL, "alloc must have control");
911 ld->set_req(0, ld_alloc->in(0));
912 }
913 } else {
914 Node* src = ac->in(ArrayCopyNode::Src);
915 Node* addp = in(MemNode::Address)->clone();
916 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
917 addp->set_req(AddPNode::Base, src);
918 addp->set_req(AddPNode::Address, src);
919
920 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
921 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
922 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
923 uint shift = exact_log2(type2aelembytes(ary_elem));
924
925 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
926 #ifdef _LP64
927 diff = phase->transform(new ConvI2LNode(diff));
928 #endif
929 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
930
931 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
932 addp->set_req(AddPNode::Offset, offset);
933 ld->set_req(MemNode::Address, phase->transform(addp));
934
935 const TypeX *ld_offs_t = phase->type(offset)->isa_intptr_t();
936
937 if (!ac->as_ArrayCopy()->can_replace_dest_load_with_src_load(ld_offs_t->_lo, ld_offs_t->_hi, phase)) {
938 return NULL;
939 }
940
941 if (in(0) != NULL) {
942 assert(ac->in(0) != NULL, "alloc must have control");
943 ld->set_req(0, ac->in(0));
944 }
945 }
946 // load depends on the tests that validate the arraycopy
947 ld->as_Load()->_control_dependency = Pinned;
948 return ld;
949 }
950 return NULL;
951 }
952
953
954 //---------------------------can_see_stored_value------------------------------
955 // This routine exists to make sure this set of tests is done the same
956 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
957 // will change the graph shape in a way which makes memory alive twice at the
958 // same time (uses the Oracle model of aliasing), then some
959 // LoadXNode::Identity will fold things back to the equivalence-class model
960 // of aliasing.
961 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
962 Node* ld_adr = in(MemNode::Address);
963 intptr_t ld_off = 0;
964 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
965 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
966 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
967 // This is more general than load from boxing objects.
968 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
969 uint alias_idx = atp->index();
970 bool final = !atp->is_rewritable();
971 Node* result = NULL;
972 Node* current = st;
973 // Skip through chains of MemBarNodes checking the MergeMems for
974 // new states for the slice of this load. Stop once any other
975 // kind of node is encountered. Loads from final memory can skip
976 // through any kind of MemBar but normal loads shouldn't skip
977 // through MemBarAcquire since the could allow them to move out of
978 // a synchronized region.
979 while (current->is_Proj()) {
980 int opc = current->in(0)->Opcode();
981 if ((final && (opc == Op_MemBarAcquire ||
982 opc == Op_MemBarAcquireLock ||
983 opc == Op_LoadFence)) ||
984 opc == Op_MemBarRelease ||
985 opc == Op_StoreFence ||
986 opc == Op_MemBarReleaseLock ||
987 opc == Op_MemBarStoreStore ||
988 opc == Op_MemBarCPUOrder) {
989 Node* mem = current->in(0)->in(TypeFunc::Memory);
990 if (mem->is_MergeMem()) {
991 MergeMemNode* merge = mem->as_MergeMem();
992 Node* new_st = merge->memory_at(alias_idx);
993 if (new_st == merge->base_memory()) {
994 // Keep searching
995 current = new_st;
996 continue;
997 }
998 // Save the new memory state for the slice and fall through
999 // to exit.
1000 result = new_st;
1001 }
1002 }
1003 break;
1004 }
1005 if (result != NULL) {
1006 st = result;
1007 }
1008 }
1009
1010 // Loop around twice in the case Load -> Initialize -> Store.
1011 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1012 for (int trip = 0; trip <= 1; trip++) {
1013
1014 if (st->is_Store()) {
1015 Node* st_adr = st->in(MemNode::Address);
1016 if (!phase->eqv(st_adr, ld_adr)) {
1017 // Try harder before giving up... Match raw and non-raw pointers.
1018 intptr_t st_off = 0;
1019 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1020 if (alloc == NULL) return NULL;
1021 if (alloc != ld_alloc) return NULL;
1022 if (ld_off != st_off) return NULL;
1023 // At this point we have proven something like this setup:
1024 // A = Allocate(...)
1025 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1026 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1027 // (Actually, we haven't yet proven the Q's are the same.)
1028 // In other words, we are loading from a casted version of
1029 // the same pointer-and-offset that we stored to.
1030 // Thus, we are able to replace L by V.
1031 }
1032 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1033 if (store_Opcode() != st->Opcode())
1034 return NULL;
1035 return st->in(MemNode::ValueIn);
1036 }
1037
1038 // A load from a freshly-created object always returns zero.
1039 // (This can happen after LoadNode::Ideal resets the load's memory input
1040 // to find_captured_store, which returned InitializeNode::zero_memory.)
1041 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1042 (st->in(0) == ld_alloc) &&
1043 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1044 // return a zero value for the load's basic type
1045 // (This is one of the few places where a generic PhaseTransform
1046 // can create new nodes. Think of it as lazily manifesting
1047 // virtually pre-existing constants.)
1048 return phase->zerocon(memory_type());
1049 }
1050
1051 // A load from an initialization barrier can match a captured store.
1052 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1053 InitializeNode* init = st->in(0)->as_Initialize();
1054 AllocateNode* alloc = init->allocation();
1055 if ((alloc != NULL) && (alloc == ld_alloc)) {
1056 // examine a captured store value
1057 st = init->find_captured_store(ld_off, memory_size(), phase);
1058 if (st != NULL) {
1059 continue; // take one more trip around
1060 }
1061 }
1062 }
1063
1064 // Load boxed value from result of valueOf() call is input parameter.
1065 if (this->is_Load() && ld_adr->is_AddP() &&
1066 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1067 intptr_t ignore = 0;
1068 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1069 if (base != NULL && base->is_Proj() &&
1070 base->as_Proj()->_con == TypeFunc::Parms &&
1071 base->in(0)->is_CallStaticJava() &&
1072 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1073 return base->in(0)->in(TypeFunc::Parms);
1074 }
1075 }
1076
1077 break;
1078 }
1079
1080 return NULL;
1081 }
1082
1083 //----------------------is_instance_field_load_with_local_phi------------------
1084 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1085 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1086 in(Address)->is_AddP() ) {
1087 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1088 // Only instances and boxed values.
1089 if( t_oop != NULL &&
1090 (t_oop->is_ptr_to_boxed_value() ||
1091 t_oop->is_known_instance_field()) &&
1092 t_oop->offset() != Type::OffsetBot &&
1093 t_oop->offset() != Type::OffsetTop) {
1094 return true;
1095 }
1096 }
1097 return false;
1098 }
1099
1100 //------------------------------Identity---------------------------------------
1101 // Loads are identity if previous store is to same address
1102 Node* LoadNode::Identity(PhaseGVN* phase) {
1103 // If the previous store-maker is the right kind of Store, and the store is
1104 // to the same address, then we are equal to the value stored.
1105 Node* mem = in(Memory);
1106 Node* value = can_see_stored_value(mem, phase);
1107 if( value ) {
1108 // byte, short & char stores truncate naturally.
1109 // A load has to load the truncated value which requires
1110 // some sort of masking operation and that requires an
1111 // Ideal call instead of an Identity call.
1112 if (memory_size() < BytesPerInt) {
1113 // If the input to the store does not fit with the load's result type,
1114 // it must be truncated via an Ideal call.
1115 if (!phase->type(value)->higher_equal(phase->type(this)))
1116 return this;
1117 }
1118 // (This works even when value is a Con, but LoadNode::Value
1119 // usually runs first, producing the singleton type of the Con.)
1120 return value;
1121 }
1122
1123 // Search for an existing data phi which was generated before for the same
1124 // instance's field to avoid infinite generation of phis in a loop.
1125 Node *region = mem->in(0);
1126 if (is_instance_field_load_with_local_phi(region)) {
1127 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1128 int this_index = phase->C->get_alias_index(addr_t);
1129 int this_offset = addr_t->offset();
1130 int this_iid = addr_t->instance_id();
1131 if (!addr_t->is_known_instance() &&
1132 addr_t->is_ptr_to_boxed_value()) {
1133 // Use _idx of address base (could be Phi node) for boxed values.
1134 intptr_t ignore = 0;
1135 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1136 if (base == NULL) {
1137 return this;
1138 }
1139 this_iid = base->_idx;
1140 }
1141 const Type* this_type = bottom_type();
1142 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1143 Node* phi = region->fast_out(i);
1144 if (phi->is_Phi() && phi != mem &&
1145 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1146 return phi;
1147 }
1148 }
1149 }
1150
1151 return this;
1152 }
1153
1154 // Construct an equivalent unsigned load.
1155 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1156 BasicType bt = T_ILLEGAL;
1157 const Type* rt = NULL;
1158 switch (Opcode()) {
1159 case Op_LoadUB: return this;
1160 case Op_LoadUS: return this;
1161 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1162 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1163 default:
1164 assert(false, "no unsigned variant: %s", Name());
1165 return NULL;
1166 }
1167 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1168 raw_adr_type(), rt, bt, _mo, _control_dependency,
1169 is_unaligned_access(), is_mismatched_access());
1170 }
1171
1172 // Construct an equivalent signed load.
1173 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1174 BasicType bt = T_ILLEGAL;
1175 const Type* rt = NULL;
1176 switch (Opcode()) {
1177 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1178 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1179 case Op_LoadB: // fall through
1180 case Op_LoadS: // fall through
1181 case Op_LoadI: // fall through
1182 case Op_LoadL: return this;
1183 default:
1184 assert(false, "no signed variant: %s", Name());
1185 return NULL;
1186 }
1187 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1188 raw_adr_type(), rt, bt, _mo, _control_dependency,
1189 is_unaligned_access(), is_mismatched_access());
1190 }
1191
1192 // We're loading from an object which has autobox behaviour.
1193 // If this object is result of a valueOf call we'll have a phi
1194 // merging a newly allocated object and a load from the cache.
1195 // We want to replace this load with the original incoming
1196 // argument to the valueOf call.
1197 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1198 assert(phase->C->eliminate_boxing(), "sanity");
1199 intptr_t ignore = 0;
1200 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1201 if ((base == NULL) || base->is_Phi()) {
1202 // Push the loads from the phi that comes from valueOf up
1203 // through it to allow elimination of the loads and the recovery
1204 // of the original value. It is done in split_through_phi().
1205 return NULL;
1206 } else if (base->is_Load() ||
1207 (base->is_DecodeN() && base->in(1)->is_Load())) {
1208 // Eliminate the load of boxed value for integer types from the cache
1209 // array by deriving the value from the index into the array.
1210 // Capture the offset of the load and then reverse the computation.
1211
1212 // Get LoadN node which loads a boxing object from 'cache' array.
1213 if (base->is_DecodeN()) {
1214 base = base->in(1);
1215 }
1216 if (!base->in(Address)->is_AddP()) {
1217 return NULL; // Complex address
1218 }
1219 AddPNode* address = base->in(Address)->as_AddP();
1220 Node* cache_base = address->in(AddPNode::Base);
1221 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1222 // Get ConP node which is static 'cache' field.
1223 cache_base = cache_base->in(1);
1224 }
1225 if ((cache_base != NULL) && cache_base->is_Con()) {
1226 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1227 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1228 Node* elements[4];
1229 int shift = exact_log2(type2aelembytes(T_OBJECT));
1230 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1231 if (count > 0 && elements[0]->is_Con() &&
1232 (count == 1 ||
1233 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1234 elements[1]->in(2) == phase->intcon(shift)))) {
1235 ciObjArray* array = base_type->const_oop()->as_obj_array();
1236 // Fetch the box object cache[0] at the base of the array and get its value
1237 ciInstance* box = array->obj_at(0)->as_instance();
1238 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1239 assert(ik->is_box_klass(), "sanity");
1240 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1241 if (ik->nof_nonstatic_fields() == 1) {
1242 // This should be true nonstatic_field_at requires calling
1243 // nof_nonstatic_fields so check it anyway
1244 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1245 BasicType bt = c.basic_type();
1246 // Only integer types have boxing cache.
1247 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1248 bt == T_BYTE || bt == T_SHORT ||
1249 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1250 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1251 if (cache_low != (int)cache_low) {
1252 return NULL; // should not happen since cache is array indexed by value
1253 }
1254 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1255 if (offset != (int)offset) {
1256 return NULL; // should not happen since cache is array indexed by value
1257 }
1258 // Add up all the offsets making of the address of the load
1259 Node* result = elements[0];
1260 for (int i = 1; i < count; i++) {
1261 result = phase->transform(new AddXNode(result, elements[i]));
1262 }
1263 // Remove the constant offset from the address and then
1264 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1265 // remove the scaling of the offset to recover the original index.
1266 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1267 // Peel the shift off directly but wrap it in a dummy node
1268 // since Ideal can't return existing nodes
1269 result = new RShiftXNode(result->in(1), phase->intcon(0));
1270 } else if (result->is_Add() && result->in(2)->is_Con() &&
1271 result->in(1)->Opcode() == Op_LShiftX &&
1272 result->in(1)->in(2) == phase->intcon(shift)) {
1273 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1274 // but for boxing cache access we know that X<<Z will not overflow
1275 // (there is range check) so we do this optimizatrion by hand here.
1276 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1277 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1278 } else {
1279 result = new RShiftXNode(result, phase->intcon(shift));
1280 }
1281 #ifdef _LP64
1282 if (bt != T_LONG) {
1283 result = new ConvL2INode(phase->transform(result));
1284 }
1285 #else
1286 if (bt == T_LONG) {
1287 result = new ConvI2LNode(phase->transform(result));
1288 }
1289 #endif
1290 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1291 // Need to preserve unboxing load type if it is unsigned.
1292 switch(this->Opcode()) {
1293 case Op_LoadUB:
1294 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1295 break;
1296 case Op_LoadUS:
1297 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1298 break;
1299 }
1300 return result;
1301 }
1302 }
1303 }
1304 }
1305 }
1306 return NULL;
1307 }
1308
1309 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1310 Node* region = phi->in(0);
1311 if (region == NULL) {
1312 return false; // Wait stable graph
1313 }
1314 uint cnt = phi->req();
1315 for (uint i = 1; i < cnt; i++) {
1316 Node* rc = region->in(i);
1317 if (rc == NULL || phase->type(rc) == Type::TOP)
1318 return false; // Wait stable graph
1319 Node* in = phi->in(i);
1320 if (in == NULL || phase->type(in) == Type::TOP)
1321 return false; // Wait stable graph
1322 }
1323 return true;
1324 }
1325 //------------------------------split_through_phi------------------------------
1326 // Split instance or boxed field load through Phi.
1327 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1328 Node* mem = in(Memory);
1329 Node* address = in(Address);
1330 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1331
1332 assert((t_oop != NULL) &&
1333 (t_oop->is_known_instance_field() ||
1334 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1335
1336 Compile* C = phase->C;
1337 intptr_t ignore = 0;
1338 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1339 bool base_is_phi = (base != NULL) && base->is_Phi();
1340 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1341 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1342 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1343
1344 if (!((mem->is_Phi() || base_is_phi) &&
1345 (load_boxed_values || t_oop->is_known_instance_field()))) {
1346 return NULL; // memory is not Phi
1347 }
1348
1349 if (mem->is_Phi()) {
1350 if (!stable_phi(mem->as_Phi(), phase)) {
1351 return NULL; // Wait stable graph
1352 }
1353 uint cnt = mem->req();
1354 // Check for loop invariant memory.
1355 if (cnt == 3) {
1356 for (uint i = 1; i < cnt; i++) {
1357 Node* in = mem->in(i);
1358 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1359 if (m == mem) {
1360 set_req(Memory, mem->in(cnt - i));
1361 return this; // made change
1362 }
1363 }
1364 }
1365 }
1366 if (base_is_phi) {
1367 if (!stable_phi(base->as_Phi(), phase)) {
1368 return NULL; // Wait stable graph
1369 }
1370 uint cnt = base->req();
1371 // Check for loop invariant memory.
1372 if (cnt == 3) {
1373 for (uint i = 1; i < cnt; i++) {
1374 if (base->in(i) == base) {
1375 return NULL; // Wait stable graph
1376 }
1377 }
1378 }
1379 }
1380
1381 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1382
1383 // Split through Phi (see original code in loopopts.cpp).
1384 assert(C->have_alias_type(t_oop), "instance should have alias type");
1385
1386 // Do nothing here if Identity will find a value
1387 // (to avoid infinite chain of value phis generation).
1388 if (!phase->eqv(this, this->Identity(phase)))
1389 return NULL;
1390
1391 // Select Region to split through.
1392 Node* region;
1393 if (!base_is_phi) {
1394 assert(mem->is_Phi(), "sanity");
1395 region = mem->in(0);
1396 // Skip if the region dominates some control edge of the address.
1397 if (!MemNode::all_controls_dominate(address, region))
1398 return NULL;
1399 } else if (!mem->is_Phi()) {
1400 assert(base_is_phi, "sanity");
1401 region = base->in(0);
1402 // Skip if the region dominates some control edge of the memory.
1403 if (!MemNode::all_controls_dominate(mem, region))
1404 return NULL;
1405 } else if (base->in(0) != mem->in(0)) {
1406 assert(base_is_phi && mem->is_Phi(), "sanity");
1407 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1408 region = base->in(0);
1409 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1410 region = mem->in(0);
1411 } else {
1412 return NULL; // complex graph
1413 }
1414 } else {
1415 assert(base->in(0) == mem->in(0), "sanity");
1416 region = mem->in(0);
1417 }
1418
1419 const Type* this_type = this->bottom_type();
1420 int this_index = C->get_alias_index(t_oop);
1421 int this_offset = t_oop->offset();
1422 int this_iid = t_oop->instance_id();
1423 if (!t_oop->is_known_instance() && load_boxed_values) {
1424 // Use _idx of address base for boxed values.
1425 this_iid = base->_idx;
1426 }
1427 PhaseIterGVN* igvn = phase->is_IterGVN();
1428 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1429 for (uint i = 1; i < region->req(); i++) {
1430 Node* x;
1431 Node* the_clone = NULL;
1432 if (region->in(i) == C->top()) {
1433 x = C->top(); // Dead path? Use a dead data op
1434 } else {
1435 x = this->clone(); // Else clone up the data op
1436 the_clone = x; // Remember for possible deletion.
1437 // Alter data node to use pre-phi inputs
1438 if (this->in(0) == region) {
1439 x->set_req(0, region->in(i));
1440 } else {
1441 x->set_req(0, NULL);
1442 }
1443 if (mem->is_Phi() && (mem->in(0) == region)) {
1444 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1445 }
1446 if (address->is_Phi() && address->in(0) == region) {
1447 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1448 }
1449 if (base_is_phi && (base->in(0) == region)) {
1450 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1451 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1452 x->set_req(Address, adr_x);
1453 }
1454 }
1455 // Check for a 'win' on some paths
1456 const Type *t = x->Value(igvn);
1457
1458 bool singleton = t->singleton();
1459
1460 // See comments in PhaseIdealLoop::split_thru_phi().
1461 if (singleton && t == Type::TOP) {
1462 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1463 }
1464
1465 if (singleton) {
1466 x = igvn->makecon(t);
1467 } else {
1468 // We now call Identity to try to simplify the cloned node.
1469 // Note that some Identity methods call phase->type(this).
1470 // Make sure that the type array is big enough for
1471 // our new node, even though we may throw the node away.
1472 // (This tweaking with igvn only works because x is a new node.)
1473 igvn->set_type(x, t);
1474 // If x is a TypeNode, capture any more-precise type permanently into Node
1475 // otherwise it will be not updated during igvn->transform since
1476 // igvn->type(x) is set to x->Value() already.
1477 x->raise_bottom_type(t);
1478 Node *y = x->Identity(igvn);
1479 if (y != x) {
1480 x = y;
1481 } else {
1482 y = igvn->hash_find_insert(x);
1483 if (y) {
1484 x = y;
1485 } else {
1486 // Else x is a new node we are keeping
1487 // We do not need register_new_node_with_optimizer
1488 // because set_type has already been called.
1489 igvn->_worklist.push(x);
1490 }
1491 }
1492 }
1493 if (x != the_clone && the_clone != NULL) {
1494 igvn->remove_dead_node(the_clone);
1495 }
1496 phi->set_req(i, x);
1497 }
1498 // Record Phi
1499 igvn->register_new_node_with_optimizer(phi);
1500 return phi;
1501 }
1502
1503 //------------------------------Ideal------------------------------------------
1504 // If the load is from Field memory and the pointer is non-null, it might be possible to
1505 // zero out the control input.
1506 // If the offset is constant and the base is an object allocation,
1507 // try to hook me up to the exact initializing store.
1508 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1509 Node* p = MemNode::Ideal_common(phase, can_reshape);
1510 if (p) return (p == NodeSentinel) ? NULL : p;
1511
1512 Node* ctrl = in(MemNode::Control);
1513 Node* address = in(MemNode::Address);
1514 bool progress = false;
1515
1516 // Skip up past a SafePoint control. Cannot do this for Stores because
1517 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1518 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1519 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1520 ctrl = ctrl->in(0);
1521 set_req(MemNode::Control,ctrl);
1522 progress = true;
1523 }
1524
1525 intptr_t ignore = 0;
1526 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1527 if (base != NULL
1528 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1529 // Check for useless control edge in some common special cases
1530 if (in(MemNode::Control) != NULL
1531 && can_remove_control()
1532 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1533 && all_controls_dominate(base, phase->C->start())) {
1534 // A method-invariant, non-null address (constant or 'this' argument).
1535 set_req(MemNode::Control, NULL);
1536 progress = true;
1537 }
1538 }
1539
1540 Node* mem = in(MemNode::Memory);
1541 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1542
1543 if (can_reshape && (addr_t != NULL)) {
1544 // try to optimize our memory input
1545 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1546 if (opt_mem != mem) {
1547 set_req(MemNode::Memory, opt_mem);
1548 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1549 return this;
1550 }
1551 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1552 if ((t_oop != NULL) &&
1553 (t_oop->is_known_instance_field() ||
1554 t_oop->is_ptr_to_boxed_value())) {
1555 PhaseIterGVN *igvn = phase->is_IterGVN();
1556 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1557 // Delay this transformation until memory Phi is processed.
1558 phase->is_IterGVN()->_worklist.push(this);
1559 return NULL;
1560 }
1561 // Split instance field load through Phi.
1562 Node* result = split_through_phi(phase);
1563 if (result != NULL) return result;
1564
1565 if (t_oop->is_ptr_to_boxed_value()) {
1566 Node* result = eliminate_autobox(phase);
1567 if (result != NULL) return result;
1568 }
1569 }
1570 }
1571
1572 // Is there a dominating load that loads the same value? Leave
1573 // anything that is not a load of a field/array element (like
1574 // barriers etc.) alone
1575 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1576 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1577 Node *use = mem->fast_out(i);
1578 if (use != this &&
1579 use->Opcode() == Opcode() &&
1580 use->in(0) != NULL &&
1581 use->in(0) != in(0) &&
1582 use->in(Address) == in(Address)) {
1583 Node* ctl = in(0);
1584 for (int i = 0; i < 10 && ctl != NULL; i++) {
1585 ctl = IfNode::up_one_dom(ctl);
1586 if (ctl == use->in(0)) {
1587 set_req(0, use->in(0));
1588 return this;
1589 }
1590 }
1591 }
1592 }
1593 }
1594
1595 // Check for prior store with a different base or offset; make Load
1596 // independent. Skip through any number of them. Bail out if the stores
1597 // are in an endless dead cycle and report no progress. This is a key
1598 // transform for Reflection. However, if after skipping through the Stores
1599 // we can't then fold up against a prior store do NOT do the transform as
1600 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1601 // array memory alive twice: once for the hoisted Load and again after the
1602 // bypassed Store. This situation only works if EVERYBODY who does
1603 // anti-dependence work knows how to bypass. I.e. we need all
1604 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1605 // the alias index stuff. So instead, peek through Stores and IFF we can
1606 // fold up, do so.
1607 Node* prev_mem = find_previous_store(phase);
1608 if (prev_mem != NULL) {
1609 Node* value = can_see_arraycopy_value(prev_mem, phase);
1610 if (value != NULL) {
1611 return value;
1612 }
1613 }
1614 // Steps (a), (b): Walk past independent stores to find an exact match.
1615 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1616 // (c) See if we can fold up on the spot, but don't fold up here.
1617 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1618 // just return a prior value, which is done by Identity calls.
1619 if (can_see_stored_value(prev_mem, phase)) {
1620 // Make ready for step (d):
1621 set_req(MemNode::Memory, prev_mem);
1622 return this;
1623 }
1624 }
1625
1626 return progress ? this : NULL;
1627 }
1628
1629 // Helper to recognize certain Klass fields which are invariant across
1630 // some group of array types (e.g., int[] or all T[] where T < Object).
1631 const Type*
1632 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1633 ciKlass* klass) const {
1634 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1635 // The field is Klass::_modifier_flags. Return its (constant) value.
1636 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1637 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1638 return TypeInt::make(klass->modifier_flags());
1639 }
1640 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1641 // The field is Klass::_access_flags. Return its (constant) value.
1642 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1643 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1644 return TypeInt::make(klass->access_flags());
1645 }
1646 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1647 // The field is Klass::_layout_helper. Return its constant value if known.
1648 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1649 return TypeInt::make(klass->layout_helper());
1650 }
1651
1652 // No match.
1653 return NULL;
1654 }
1655
1656 //------------------------------Value-----------------------------------------
1657 const Type* LoadNode::Value(PhaseGVN* phase) const {
1658 // Either input is TOP ==> the result is TOP
1659 Node* mem = in(MemNode::Memory);
1660 const Type *t1 = phase->type(mem);
1661 if (t1 == Type::TOP) return Type::TOP;
1662 Node* adr = in(MemNode::Address);
1663 const TypePtr* tp = phase->type(adr)->isa_ptr();
1664 if (tp == NULL || tp->empty()) return Type::TOP;
1665 int off = tp->offset();
1666 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1667 Compile* C = phase->C;
1668
1669 // Try to guess loaded type from pointer type
1670 if (tp->isa_aryptr()) {
1671 const TypeAryPtr* ary = tp->is_aryptr();
1672 const Type* t = ary->elem();
1673
1674 // Determine whether the reference is beyond the header or not, by comparing
1675 // the offset against the offset of the start of the array's data.
1676 // Different array types begin at slightly different offsets (12 vs. 16).
1677 // We choose T_BYTE as an example base type that is least restrictive
1678 // as to alignment, which will therefore produce the smallest
1679 // possible base offset.
1680 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1681 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1682
1683 // Try to constant-fold a stable array element.
1684 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1685 // Make sure the reference is not into the header and the offset is constant
1686 ciObject* aobj = ary->const_oop();
1687 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1688 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1689 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1690 stable_dimension,
1691 memory_type(), is_unsigned());
1692 if (con_type != NULL) {
1693 return con_type;
1694 }
1695 }
1696 }
1697
1698 // Don't do this for integer types. There is only potential profit if
1699 // the element type t is lower than _type; that is, for int types, if _type is
1700 // more restrictive than t. This only happens here if one is short and the other
1701 // char (both 16 bits), and in those cases we've made an intentional decision
1702 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1703 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1704 //
1705 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1706 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1707 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1708 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1709 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1710 // In fact, that could have been the original type of p1, and p1 could have
1711 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1712 // expression (LShiftL quux 3) independently optimized to the constant 8.
1713 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1714 && (_type->isa_vect() == NULL)
1715 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1716 // t might actually be lower than _type, if _type is a unique
1717 // concrete subclass of abstract class t.
1718 if (off_beyond_header) { // is the offset beyond the header?
1719 const Type* jt = t->join_speculative(_type);
1720 // In any case, do not allow the join, per se, to empty out the type.
1721 if (jt->empty() && !t->empty()) {
1722 // This can happen if a interface-typed array narrows to a class type.
1723 jt = _type;
1724 }
1725 #ifdef ASSERT
1726 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1727 // The pointers in the autobox arrays are always non-null
1728 Node* base = adr->in(AddPNode::Base);
1729 if ((base != NULL) && base->is_DecodeN()) {
1730 // Get LoadN node which loads IntegerCache.cache field
1731 base = base->in(1);
1732 }
1733 if ((base != NULL) && base->is_Con()) {
1734 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1735 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1736 // It could be narrow oop
1737 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1738 }
1739 }
1740 }
1741 #endif
1742 return jt;
1743 }
1744 }
1745 } else if (tp->base() == Type::InstPtr) {
1746 assert( off != Type::OffsetBot ||
1747 // arrays can be cast to Objects
1748 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1749 // unsafe field access may not have a constant offset
1750 C->has_unsafe_access(),
1751 "Field accesses must be precise" );
1752 // For oop loads, we expect the _type to be precise.
1753
1754 // Optimize loads from constant fields.
1755 const TypeInstPtr* tinst = tp->is_instptr();
1756 ciObject* const_oop = tinst->const_oop();
1757 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1758 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1759 if (con_type != NULL) {
1760 return con_type;
1761 }
1762 }
1763 } else if (tp->base() == Type::KlassPtr) {
1764 assert( off != Type::OffsetBot ||
1765 // arrays can be cast to Objects
1766 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1767 // also allow array-loading from the primary supertype
1768 // array during subtype checks
1769 Opcode() == Op_LoadKlass,
1770 "Field accesses must be precise" );
1771 // For klass/static loads, we expect the _type to be precise
1772 }
1773
1774 const TypeKlassPtr *tkls = tp->isa_klassptr();
1775 if (tkls != NULL && !StressReflectiveCode) {
1776 ciKlass* klass = tkls->klass();
1777 if (klass->is_loaded() && tkls->klass_is_exact()) {
1778 // We are loading a field from a Klass metaobject whose identity
1779 // is known at compile time (the type is "exact" or "precise").
1780 // Check for fields we know are maintained as constants by the VM.
1781 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1782 // The field is Klass::_super_check_offset. Return its (constant) value.
1783 // (Folds up type checking code.)
1784 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1785 return TypeInt::make(klass->super_check_offset());
1786 }
1787 // Compute index into primary_supers array
1788 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1789 // Check for overflowing; use unsigned compare to handle the negative case.
1790 if( depth < ciKlass::primary_super_limit() ) {
1791 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1792 // (Folds up type checking code.)
1793 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1794 ciKlass *ss = klass->super_of_depth(depth);
1795 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1796 }
1797 const Type* aift = load_array_final_field(tkls, klass);
1798 if (aift != NULL) return aift;
1799 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1800 // The field is Klass::_java_mirror. Return its (constant) value.
1801 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1802 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1803 return TypeInstPtr::make(klass->java_mirror());
1804 }
1805 }
1806
1807 // We can still check if we are loading from the primary_supers array at a
1808 // shallow enough depth. Even though the klass is not exact, entries less
1809 // than or equal to its super depth are correct.
1810 if (klass->is_loaded() ) {
1811 ciType *inner = klass;
1812 while( inner->is_obj_array_klass() )
1813 inner = inner->as_obj_array_klass()->base_element_type();
1814 if( inner->is_instance_klass() &&
1815 !inner->as_instance_klass()->flags().is_interface() ) {
1816 // Compute index into primary_supers array
1817 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1818 // Check for overflowing; use unsigned compare to handle the negative case.
1819 if( depth < ciKlass::primary_super_limit() &&
1820 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1821 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1822 // (Folds up type checking code.)
1823 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1824 ciKlass *ss = klass->super_of_depth(depth);
1825 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1826 }
1827 }
1828 }
1829
1830 // If the type is enough to determine that the thing is not an array,
1831 // we can give the layout_helper a positive interval type.
1832 // This will help short-circuit some reflective code.
1833 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1834 && !klass->is_array_klass() // not directly typed as an array
1835 && !klass->is_interface() // specifically not Serializable & Cloneable
1836 && !klass->is_java_lang_Object() // not the supertype of all T[]
1837 ) {
1838 // Note: When interfaces are reliable, we can narrow the interface
1839 // test to (klass != Serializable && klass != Cloneable).
1840 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1841 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1842 // The key property of this type is that it folds up tests
1843 // for array-ness, since it proves that the layout_helper is positive.
1844 // Thus, a generic value like the basic object layout helper works fine.
1845 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1846 }
1847 }
1848
1849 // If we are loading from a freshly-allocated object, produce a zero,
1850 // if the load is provably beyond the header of the object.
1851 // (Also allow a variable load from a fresh array to produce zero.)
1852 const TypeOopPtr *tinst = tp->isa_oopptr();
1853 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1854 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1855 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1856 Node* value = can_see_stored_value(mem,phase);
1857 if (value != NULL && value->is_Con()) {
1858 assert(value->bottom_type()->higher_equal(_type),"sanity");
1859 return value->bottom_type();
1860 }
1861 }
1862
1863 if (is_instance) {
1864 // If we have an instance type and our memory input is the
1865 // programs's initial memory state, there is no matching store,
1866 // so just return a zero of the appropriate type
1867 Node *mem = in(MemNode::Memory);
1868 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1869 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1870 return Type::get_zero_type(_type->basic_type());
1871 }
1872 }
1873 return _type;
1874 }
1875
1876 //------------------------------match_edge-------------------------------------
1877 // Do we Match on this edge index or not? Match only the address.
1878 uint LoadNode::match_edge(uint idx) const {
1879 return idx == MemNode::Address;
1880 }
1881
1882 //--------------------------LoadBNode::Ideal--------------------------------------
1883 //
1884 // If the previous store is to the same address as this load,
1885 // and the value stored was larger than a byte, replace this load
1886 // with the value stored truncated to a byte. If no truncation is
1887 // needed, the replacement is done in LoadNode::Identity().
1888 //
1889 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1890 Node* mem = in(MemNode::Memory);
1891 Node* value = can_see_stored_value(mem,phase);
1892 if( value && !phase->type(value)->higher_equal( _type ) ) {
1893 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1894 return new RShiftINode(result, phase->intcon(24));
1895 }
1896 // Identity call will handle the case where truncation is not needed.
1897 return LoadNode::Ideal(phase, can_reshape);
1898 }
1899
1900 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1901 Node* mem = in(MemNode::Memory);
1902 Node* value = can_see_stored_value(mem,phase);
1903 if (value != NULL && value->is_Con() &&
1904 !value->bottom_type()->higher_equal(_type)) {
1905 // If the input to the store does not fit with the load's result type,
1906 // it must be truncated. We can't delay until Ideal call since
1907 // a singleton Value is needed for split_thru_phi optimization.
1908 int con = value->get_int();
1909 return TypeInt::make((con << 24) >> 24);
1910 }
1911 return LoadNode::Value(phase);
1912 }
1913
1914 //--------------------------LoadUBNode::Ideal-------------------------------------
1915 //
1916 // If the previous store is to the same address as this load,
1917 // and the value stored was larger than a byte, replace this load
1918 // with the value stored truncated to a byte. If no truncation is
1919 // needed, the replacement is done in LoadNode::Identity().
1920 //
1921 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1922 Node* mem = in(MemNode::Memory);
1923 Node* value = can_see_stored_value(mem, phase);
1924 if (value && !phase->type(value)->higher_equal(_type))
1925 return new AndINode(value, phase->intcon(0xFF));
1926 // Identity call will handle the case where truncation is not needed.
1927 return LoadNode::Ideal(phase, can_reshape);
1928 }
1929
1930 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
1931 Node* mem = in(MemNode::Memory);
1932 Node* value = can_see_stored_value(mem,phase);
1933 if (value != NULL && value->is_Con() &&
1934 !value->bottom_type()->higher_equal(_type)) {
1935 // If the input to the store does not fit with the load's result type,
1936 // it must be truncated. We can't delay until Ideal call since
1937 // a singleton Value is needed for split_thru_phi optimization.
1938 int con = value->get_int();
1939 return TypeInt::make(con & 0xFF);
1940 }
1941 return LoadNode::Value(phase);
1942 }
1943
1944 //--------------------------LoadUSNode::Ideal-------------------------------------
1945 //
1946 // If the previous store is to the same address as this load,
1947 // and the value stored was larger than a char, replace this load
1948 // with the value stored truncated to a char. If no truncation is
1949 // needed, the replacement is done in LoadNode::Identity().
1950 //
1951 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1952 Node* mem = in(MemNode::Memory);
1953 Node* value = can_see_stored_value(mem,phase);
1954 if( value && !phase->type(value)->higher_equal( _type ) )
1955 return new AndINode(value,phase->intcon(0xFFFF));
1956 // Identity call will handle the case where truncation is not needed.
1957 return LoadNode::Ideal(phase, can_reshape);
1958 }
1959
1960 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
1961 Node* mem = in(MemNode::Memory);
1962 Node* value = can_see_stored_value(mem,phase);
1963 if (value != NULL && value->is_Con() &&
1964 !value->bottom_type()->higher_equal(_type)) {
1965 // If the input to the store does not fit with the load's result type,
1966 // it must be truncated. We can't delay until Ideal call since
1967 // a singleton Value is needed for split_thru_phi optimization.
1968 int con = value->get_int();
1969 return TypeInt::make(con & 0xFFFF);
1970 }
1971 return LoadNode::Value(phase);
1972 }
1973
1974 //--------------------------LoadSNode::Ideal--------------------------------------
1975 //
1976 // If the previous store is to the same address as this load,
1977 // and the value stored was larger than a short, replace this load
1978 // with the value stored truncated to a short. If no truncation is
1979 // needed, the replacement is done in LoadNode::Identity().
1980 //
1981 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1982 Node* mem = in(MemNode::Memory);
1983 Node* value = can_see_stored_value(mem,phase);
1984 if( value && !phase->type(value)->higher_equal( _type ) ) {
1985 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
1986 return new RShiftINode(result, phase->intcon(16));
1987 }
1988 // Identity call will handle the case where truncation is not needed.
1989 return LoadNode::Ideal(phase, can_reshape);
1990 }
1991
1992 const Type* LoadSNode::Value(PhaseGVN* phase) const {
1993 Node* mem = in(MemNode::Memory);
1994 Node* value = can_see_stored_value(mem,phase);
1995 if (value != NULL && value->is_Con() &&
1996 !value->bottom_type()->higher_equal(_type)) {
1997 // If the input to the store does not fit with the load's result type,
1998 // it must be truncated. We can't delay until Ideal call since
1999 // a singleton Value is needed for split_thru_phi optimization.
2000 int con = value->get_int();
2001 return TypeInt::make((con << 16) >> 16);
2002 }
2003 return LoadNode::Value(phase);
2004 }
2005
2006 //=============================================================================
2007 //----------------------------LoadKlassNode::make------------------------------
2008 // Polymorphic factory method:
2009 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2010 // sanity check the alias category against the created node type
2011 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2012 assert(adr_type != NULL, "expecting TypeKlassPtr");
2013 #ifdef _LP64
2014 if (adr_type->is_ptr_to_narrowklass()) {
2015 assert(UseCompressedClassPointers, "no compressed klasses");
2016 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2017 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2018 }
2019 #endif
2020 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2021 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2022 }
2023
2024 //------------------------------Value------------------------------------------
2025 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2026 return klass_value_common(phase);
2027 }
2028
2029 // In most cases, LoadKlassNode does not have the control input set. If the control
2030 // input is set, it must not be removed (by LoadNode::Ideal()).
2031 bool LoadKlassNode::can_remove_control() const {
2032 return false;
2033 }
2034
2035 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2036 // Either input is TOP ==> the result is TOP
2037 const Type *t1 = phase->type( in(MemNode::Memory) );
2038 if (t1 == Type::TOP) return Type::TOP;
2039 Node *adr = in(MemNode::Address);
2040 const Type *t2 = phase->type( adr );
2041 if (t2 == Type::TOP) return Type::TOP;
2042 const TypePtr *tp = t2->is_ptr();
2043 if (TypePtr::above_centerline(tp->ptr()) ||
2044 tp->ptr() == TypePtr::Null) return Type::TOP;
2045
2046 // Return a more precise klass, if possible
2047 const TypeInstPtr *tinst = tp->isa_instptr();
2048 if (tinst != NULL) {
2049 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2050 int offset = tinst->offset();
2051 if (ik == phase->C->env()->Class_klass()
2052 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2053 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2054 // We are loading a special hidden field from a Class mirror object,
2055 // the field which points to the VM's Klass metaobject.
2056 ciType* t = tinst->java_mirror_type();
2057 // java_mirror_type returns non-null for compile-time Class constants.
2058 if (t != NULL) {
2059 // constant oop => constant klass
2060 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2061 if (t->is_void()) {
2062 // We cannot create a void array. Since void is a primitive type return null
2063 // klass. Users of this result need to do a null check on the returned klass.
2064 return TypePtr::NULL_PTR;
2065 }
2066 return TypeKlassPtr::make(ciArrayKlass::make(t));
2067 }
2068 if (!t->is_klass()) {
2069 // a primitive Class (e.g., int.class) has NULL for a klass field
2070 return TypePtr::NULL_PTR;
2071 }
2072 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2073 return TypeKlassPtr::make(t->as_klass());
2074 }
2075 // non-constant mirror, so we can't tell what's going on
2076 }
2077 if( !ik->is_loaded() )
2078 return _type; // Bail out if not loaded
2079 if (offset == oopDesc::klass_offset_in_bytes()) {
2080 if (tinst->klass_is_exact()) {
2081 return TypeKlassPtr::make(ik);
2082 }
2083 // See if we can become precise: no subklasses and no interface
2084 // (Note: We need to support verified interfaces.)
2085 if (!ik->is_interface() && !ik->has_subklass()) {
2086 //assert(!UseExactTypes, "this code should be useless with exact types");
2087 // Add a dependence; if any subclass added we need to recompile
2088 if (!ik->is_final()) {
2089 // %%% should use stronger assert_unique_concrete_subtype instead
2090 phase->C->dependencies()->assert_leaf_type(ik);
2091 }
2092 // Return precise klass
2093 return TypeKlassPtr::make(ik);
2094 }
2095
2096 // Return root of possible klass
2097 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2098 }
2099 }
2100
2101 // Check for loading klass from an array
2102 const TypeAryPtr *tary = tp->isa_aryptr();
2103 if( tary != NULL ) {
2104 ciKlass *tary_klass = tary->klass();
2105 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2106 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2107 if (tary->klass_is_exact()) {
2108 return TypeKlassPtr::make(tary_klass);
2109 }
2110 ciArrayKlass *ak = tary->klass()->as_array_klass();
2111 // If the klass is an object array, we defer the question to the
2112 // array component klass.
2113 if( ak->is_obj_array_klass() ) {
2114 assert( ak->is_loaded(), "" );
2115 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2116 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2117 ciInstanceKlass* ik = base_k->as_instance_klass();
2118 // See if we can become precise: no subklasses and no interface
2119 if (!ik->is_interface() && !ik->has_subklass()) {
2120 //assert(!UseExactTypes, "this code should be useless with exact types");
2121 // Add a dependence; if any subclass added we need to recompile
2122 if (!ik->is_final()) {
2123 phase->C->dependencies()->assert_leaf_type(ik);
2124 }
2125 // Return precise array klass
2126 return TypeKlassPtr::make(ak);
2127 }
2128 }
2129 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2130 } else { // Found a type-array?
2131 //assert(!UseExactTypes, "this code should be useless with exact types");
2132 assert( ak->is_type_array_klass(), "" );
2133 return TypeKlassPtr::make(ak); // These are always precise
2134 }
2135 }
2136 }
2137
2138 // Check for loading klass from an array klass
2139 const TypeKlassPtr *tkls = tp->isa_klassptr();
2140 if (tkls != NULL && !StressReflectiveCode) {
2141 ciKlass* klass = tkls->klass();
2142 if( !klass->is_loaded() )
2143 return _type; // Bail out if not loaded
2144 if( klass->is_obj_array_klass() &&
2145 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2146 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2147 // // Always returning precise element type is incorrect,
2148 // // e.g., element type could be object and array may contain strings
2149 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2150
2151 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2152 // according to the element type's subclassing.
2153 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2154 }
2155 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2156 tkls->offset() == in_bytes(Klass::super_offset())) {
2157 ciKlass* sup = klass->as_instance_klass()->super();
2158 // The field is Klass::_super. Return its (constant) value.
2159 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2160 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2161 }
2162 }
2163
2164 // Bailout case
2165 return LoadNode::Value(phase);
2166 }
2167
2168 //------------------------------Identity---------------------------------------
2169 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2170 // Also feed through the klass in Allocate(...klass...)._klass.
2171 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2172 return klass_identity_common(phase);
2173 }
2174
2175 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2176 Node* x = LoadNode::Identity(phase);
2177 if (x != this) return x;
2178
2179 // Take apart the address into an oop and and offset.
2180 // Return 'this' if we cannot.
2181 Node* adr = in(MemNode::Address);
2182 intptr_t offset = 0;
2183 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2184 if (base == NULL) return this;
2185 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2186 if (toop == NULL) return this;
2187
2188 // We can fetch the klass directly through an AllocateNode.
2189 // This works even if the klass is not constant (clone or newArray).
2190 if (offset == oopDesc::klass_offset_in_bytes()) {
2191 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2192 if (allocated_klass != NULL) {
2193 return allocated_klass;
2194 }
2195 }
2196
2197 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2198 // See inline_native_Class_query for occurrences of these patterns.
2199 // Java Example: x.getClass().isAssignableFrom(y)
2200 //
2201 // This improves reflective code, often making the Class
2202 // mirror go completely dead. (Current exception: Class
2203 // mirrors may appear in debug info, but we could clean them out by
2204 // introducing a new debug info operator for Klass*.java_mirror).
2205 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2206 && offset == java_lang_Class::klass_offset_in_bytes()) {
2207 // We are loading a special hidden field from a Class mirror,
2208 // the field which points to its Klass or ArrayKlass metaobject.
2209 if (base->is_Load()) {
2210 Node* adr2 = base->in(MemNode::Address);
2211 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2212 if (tkls != NULL && !tkls->empty()
2213 && (tkls->klass()->is_instance_klass() ||
2214 tkls->klass()->is_array_klass())
2215 && adr2->is_AddP()
2216 ) {
2217 int mirror_field = in_bytes(Klass::java_mirror_offset());
2218 if (tkls->offset() == mirror_field) {
2219 return adr2->in(AddPNode::Base);
2220 }
2221 }
2222 }
2223 }
2224
2225 return this;
2226 }
2227
2228
2229 //------------------------------Value------------------------------------------
2230 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2231 const Type *t = klass_value_common(phase);
2232 if (t == Type::TOP)
2233 return t;
2234
2235 return t->make_narrowklass();
2236 }
2237
2238 //------------------------------Identity---------------------------------------
2239 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2240 // Also feed through the klass in Allocate(...klass...)._klass.
2241 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2242 Node *x = klass_identity_common(phase);
2243
2244 const Type *t = phase->type( x );
2245 if( t == Type::TOP ) return x;
2246 if( t->isa_narrowklass()) return x;
2247 assert (!t->isa_narrowoop(), "no narrow oop here");
2248
2249 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2250 }
2251
2252 //------------------------------Value-----------------------------------------
2253 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2254 // Either input is TOP ==> the result is TOP
2255 const Type *t1 = phase->type( in(MemNode::Memory) );
2256 if( t1 == Type::TOP ) return Type::TOP;
2257 Node *adr = in(MemNode::Address);
2258 const Type *t2 = phase->type( adr );
2259 if( t2 == Type::TOP ) return Type::TOP;
2260 const TypePtr *tp = t2->is_ptr();
2261 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2262 const TypeAryPtr *tap = tp->isa_aryptr();
2263 if( !tap ) return _type;
2264 return tap->size();
2265 }
2266
2267 //-------------------------------Ideal---------------------------------------
2268 // Feed through the length in AllocateArray(...length...)._length.
2269 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2270 Node* p = MemNode::Ideal_common(phase, can_reshape);
2271 if (p) return (p == NodeSentinel) ? NULL : p;
2272
2273 // Take apart the address into an oop and and offset.
2274 // Return 'this' if we cannot.
2275 Node* adr = in(MemNode::Address);
2276 intptr_t offset = 0;
2277 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2278 if (base == NULL) return NULL;
2279 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2280 if (tary == NULL) return NULL;
2281
2282 // We can fetch the length directly through an AllocateArrayNode.
2283 // This works even if the length is not constant (clone or newArray).
2284 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2285 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2286 if (alloc != NULL) {
2287 Node* allocated_length = alloc->Ideal_length();
2288 Node* len = alloc->make_ideal_length(tary, phase);
2289 if (allocated_length != len) {
2290 // New CastII improves on this.
2291 return len;
2292 }
2293 }
2294 }
2295
2296 return NULL;
2297 }
2298
2299 //------------------------------Identity---------------------------------------
2300 // Feed through the length in AllocateArray(...length...)._length.
2301 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2302 Node* x = LoadINode::Identity(phase);
2303 if (x != this) return x;
2304
2305 // Take apart the address into an oop and and offset.
2306 // Return 'this' if we cannot.
2307 Node* adr = in(MemNode::Address);
2308 intptr_t offset = 0;
2309 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2310 if (base == NULL) return this;
2311 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2312 if (tary == NULL) return this;
2313
2314 // We can fetch the length directly through an AllocateArrayNode.
2315 // This works even if the length is not constant (clone or newArray).
2316 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2317 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2318 if (alloc != NULL) {
2319 Node* allocated_length = alloc->Ideal_length();
2320 // Do not allow make_ideal_length to allocate a CastII node.
2321 Node* len = alloc->make_ideal_length(tary, phase, false);
2322 if (allocated_length == len) {
2323 // Return allocated_length only if it would not be improved by a CastII.
2324 return allocated_length;
2325 }
2326 }
2327 }
2328
2329 return this;
2330
2331 }
2332
2333 //=============================================================================
2334 //---------------------------StoreNode::make-----------------------------------
2335 // Polymorphic factory method:
2336 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2337 assert((mo == unordered || mo == release), "unexpected");
2338 Compile* C = gvn.C;
2339 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2340 ctl != NULL, "raw memory operations should have control edge");
2341
2342 switch (bt) {
2343 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2344 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2345 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2346 case T_CHAR:
2347 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2348 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2349 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2350 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2351 case T_METADATA:
2352 case T_ADDRESS:
2353 case T_OBJECT:
2354 #ifdef _LP64
2355 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2356 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2357 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2358 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2359 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2360 adr->bottom_type()->isa_rawptr())) {
2361 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2362 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2363 }
2364 #endif
2365 {
2366 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2367 }
2368 default:
2369 ShouldNotReachHere();
2370 return (StoreNode*)NULL;
2371 }
2372 }
2373
2374 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2375 bool require_atomic = true;
2376 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2377 }
2378
2379 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2380 bool require_atomic = true;
2381 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2382 }
2383
2384
2385 //--------------------------bottom_type----------------------------------------
2386 const Type *StoreNode::bottom_type() const {
2387 return Type::MEMORY;
2388 }
2389
2390 //------------------------------hash-------------------------------------------
2391 uint StoreNode::hash() const {
2392 // unroll addition of interesting fields
2393 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2394
2395 // Since they are not commoned, do not hash them:
2396 return NO_HASH;
2397 }
2398
2399 //------------------------------Ideal------------------------------------------
2400 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2401 // When a store immediately follows a relevant allocation/initialization,
2402 // try to capture it into the initialization, or hoist it above.
2403 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2404 Node* p = MemNode::Ideal_common(phase, can_reshape);
2405 if (p) return (p == NodeSentinel) ? NULL : p;
2406
2407 Node* mem = in(MemNode::Memory);
2408 Node* address = in(MemNode::Address);
2409 // Back-to-back stores to same address? Fold em up. Generally
2410 // unsafe if I have intervening uses... Also disallowed for StoreCM
2411 // since they must follow each StoreP operation. Redundant StoreCMs
2412 // are eliminated just before matching in final_graph_reshape.
2413 {
2414 Node* st = mem;
2415 // If Store 'st' has more than one use, we cannot fold 'st' away.
2416 // For example, 'st' might be the final state at a conditional
2417 // return. Or, 'st' might be used by some node which is live at
2418 // the same time 'st' is live, which might be unschedulable. So,
2419 // require exactly ONE user until such time as we clone 'mem' for
2420 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2421 // true).
2422 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2423 // Looking at a dead closed cycle of memory?
2424 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2425 assert(Opcode() == st->Opcode() ||
2426 st->Opcode() == Op_StoreVector ||
2427 Opcode() == Op_StoreVector ||
2428 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2429 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2430 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2431 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2432
2433 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2434 st->as_Store()->memory_size() <= this->memory_size()) {
2435 Node* use = st->raw_out(0);
2436 phase->igvn_rehash_node_delayed(use);
2437 if (can_reshape) {
2438 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2439 } else {
2440 // It's OK to do this in the parser, since DU info is always accurate,
2441 // and the parser always refers to nodes via SafePointNode maps.
2442 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2443 }
2444 return this;
2445 }
2446 st = st->in(MemNode::Memory);
2447 }
2448 }
2449
2450
2451 // Capture an unaliased, unconditional, simple store into an initializer.
2452 // Or, if it is independent of the allocation, hoist it above the allocation.
2453 if (ReduceFieldZeroing && /*can_reshape &&*/
2454 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2455 InitializeNode* init = mem->in(0)->as_Initialize();
2456 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2457 if (offset > 0) {
2458 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2459 // If the InitializeNode captured me, it made a raw copy of me,
2460 // and I need to disappear.
2461 if (moved != NULL) {
2462 // %%% hack to ensure that Ideal returns a new node:
2463 mem = MergeMemNode::make(mem);
2464 return mem; // fold me away
2465 }
2466 }
2467 }
2468
2469 return NULL; // No further progress
2470 }
2471
2472 //------------------------------Value-----------------------------------------
2473 const Type* StoreNode::Value(PhaseGVN* phase) const {
2474 // Either input is TOP ==> the result is TOP
2475 const Type *t1 = phase->type( in(MemNode::Memory) );
2476 if( t1 == Type::TOP ) return Type::TOP;
2477 const Type *t2 = phase->type( in(MemNode::Address) );
2478 if( t2 == Type::TOP ) return Type::TOP;
2479 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2480 if( t3 == Type::TOP ) return Type::TOP;
2481 return Type::MEMORY;
2482 }
2483
2484 //------------------------------Identity---------------------------------------
2485 // Remove redundant stores:
2486 // Store(m, p, Load(m, p)) changes to m.
2487 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2488 Node* StoreNode::Identity(PhaseGVN* phase) {
2489 Node* mem = in(MemNode::Memory);
2490 Node* adr = in(MemNode::Address);
2491 Node* val = in(MemNode::ValueIn);
2492
2493 // Load then Store? Then the Store is useless
2494 if (val->is_Load() &&
2495 val->in(MemNode::Address)->eqv_uncast(adr) &&
2496 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2497 val->as_Load()->store_Opcode() == Opcode()) {
2498 return mem;
2499 }
2500
2501 // Two stores in a row of the same value?
2502 if (mem->is_Store() &&
2503 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2504 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2505 mem->Opcode() == Opcode()) {
2506 return mem;
2507 }
2508
2509 // Store of zero anywhere into a freshly-allocated object?
2510 // Then the store is useless.
2511 // (It must already have been captured by the InitializeNode.)
2512 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2513 // a newly allocated object is already all-zeroes everywhere
2514 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2515 return mem;
2516 }
2517
2518 // the store may also apply to zero-bits in an earlier object
2519 Node* prev_mem = find_previous_store(phase);
2520 // Steps (a), (b): Walk past independent stores to find an exact match.
2521 if (prev_mem != NULL) {
2522 Node* prev_val = can_see_stored_value(prev_mem, phase);
2523 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2524 // prev_val and val might differ by a cast; it would be good
2525 // to keep the more informative of the two.
2526 return mem;
2527 }
2528 }
2529 }
2530
2531 return this;
2532 }
2533
2534 //------------------------------match_edge-------------------------------------
2535 // Do we Match on this edge index or not? Match only memory & value
2536 uint StoreNode::match_edge(uint idx) const {
2537 return idx == MemNode::Address || idx == MemNode::ValueIn;
2538 }
2539
2540 //------------------------------cmp--------------------------------------------
2541 // Do not common stores up together. They generally have to be split
2542 // back up anyways, so do not bother.
2543 uint StoreNode::cmp( const Node &n ) const {
2544 return (&n == this); // Always fail except on self
2545 }
2546
2547 //------------------------------Ideal_masked_input-----------------------------
2548 // Check for a useless mask before a partial-word store
2549 // (StoreB ... (AndI valIn conIa) )
2550 // If (conIa & mask == mask) this simplifies to
2551 // (StoreB ... (valIn) )
2552 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2553 Node *val = in(MemNode::ValueIn);
2554 if( val->Opcode() == Op_AndI ) {
2555 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2556 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2557 set_req(MemNode::ValueIn, val->in(1));
2558 return this;
2559 }
2560 }
2561 return NULL;
2562 }
2563
2564
2565 //------------------------------Ideal_sign_extended_input----------------------
2566 // Check for useless sign-extension before a partial-word store
2567 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2568 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2569 // (StoreB ... (valIn) )
2570 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2571 Node *val = in(MemNode::ValueIn);
2572 if( val->Opcode() == Op_RShiftI ) {
2573 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2574 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2575 Node *shl = val->in(1);
2576 if( shl->Opcode() == Op_LShiftI ) {
2577 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2578 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2579 set_req(MemNode::ValueIn, shl->in(1));
2580 return this;
2581 }
2582 }
2583 }
2584 }
2585 return NULL;
2586 }
2587
2588 //------------------------------value_never_loaded-----------------------------------
2589 // Determine whether there are any possible loads of the value stored.
2590 // For simplicity, we actually check if there are any loads from the
2591 // address stored to, not just for loads of the value stored by this node.
2592 //
2593 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2594 Node *adr = in(Address);
2595 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2596 if (adr_oop == NULL)
2597 return false;
2598 if (!adr_oop->is_known_instance_field())
2599 return false; // if not a distinct instance, there may be aliases of the address
2600 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2601 Node *use = adr->fast_out(i);
2602 if (use->is_Load() || use->is_LoadStore()) {
2603 return false;
2604 }
2605 }
2606 return true;
2607 }
2608
2609 //=============================================================================
2610 //------------------------------Ideal------------------------------------------
2611 // If the store is from an AND mask that leaves the low bits untouched, then
2612 // we can skip the AND operation. If the store is from a sign-extension
2613 // (a left shift, then right shift) we can skip both.
2614 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2615 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2616 if( progress != NULL ) return progress;
2617
2618 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2619 if( progress != NULL ) return progress;
2620
2621 // Finally check the default case
2622 return StoreNode::Ideal(phase, can_reshape);
2623 }
2624
2625 //=============================================================================
2626 //------------------------------Ideal------------------------------------------
2627 // If the store is from an AND mask that leaves the low bits untouched, then
2628 // we can skip the AND operation
2629 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2630 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2631 if( progress != NULL ) return progress;
2632
2633 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2634 if( progress != NULL ) return progress;
2635
2636 // Finally check the default case
2637 return StoreNode::Ideal(phase, can_reshape);
2638 }
2639
2640 //=============================================================================
2641 //------------------------------Identity---------------------------------------
2642 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2643 // No need to card mark when storing a null ptr
2644 Node* my_store = in(MemNode::OopStore);
2645 if (my_store->is_Store()) {
2646 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2647 if( t1 == TypePtr::NULL_PTR ) {
2648 return in(MemNode::Memory);
2649 }
2650 }
2651 return this;
2652 }
2653
2654 //=============================================================================
2655 //------------------------------Ideal---------------------------------------
2656 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2657 Node* progress = StoreNode::Ideal(phase, can_reshape);
2658 if (progress != NULL) return progress;
2659
2660 Node* my_store = in(MemNode::OopStore);
2661 if (my_store->is_MergeMem()) {
2662 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2663 set_req(MemNode::OopStore, mem);
2664 return this;
2665 }
2666
2667 return NULL;
2668 }
2669
2670 //------------------------------Value-----------------------------------------
2671 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2672 // Either input is TOP ==> the result is TOP
2673 const Type *t = phase->type( in(MemNode::Memory) );
2674 if( t == Type::TOP ) return Type::TOP;
2675 t = phase->type( in(MemNode::Address) );
2676 if( t == Type::TOP ) return Type::TOP;
2677 t = phase->type( in(MemNode::ValueIn) );
2678 if( t == Type::TOP ) return Type::TOP;
2679 // If extra input is TOP ==> the result is TOP
2680 t = phase->type( in(MemNode::OopStore) );
2681 if( t == Type::TOP ) return Type::TOP;
2682
2683 return StoreNode::Value( phase );
2684 }
2685
2686
2687 //=============================================================================
2688 //----------------------------------SCMemProjNode------------------------------
2689 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2690 {
2691 return bottom_type();
2692 }
2693
2694 //=============================================================================
2695 //----------------------------------LoadStoreNode------------------------------
2696 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2697 : Node(required),
2698 _type(rt),
2699 _adr_type(at)
2700 {
2701 init_req(MemNode::Control, c );
2702 init_req(MemNode::Memory , mem);
2703 init_req(MemNode::Address, adr);
2704 init_req(MemNode::ValueIn, val);
2705 init_class_id(Class_LoadStore);
2706 }
2707
2708 uint LoadStoreNode::ideal_reg() const {
2709 return _type->ideal_reg();
2710 }
2711
2712 bool LoadStoreNode::result_not_used() const {
2713 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2714 Node *x = fast_out(i);
2715 if (x->Opcode() == Op_SCMemProj) continue;
2716 return false;
2717 }
2718 return true;
2719 }
2720
2721 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2722
2723 //=============================================================================
2724 //----------------------------------LoadStoreConditionalNode--------------------
2725 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2726 init_req(ExpectedIn, ex );
2727 }
2728
2729 //=============================================================================
2730 //-------------------------------adr_type--------------------------------------
2731 const TypePtr* ClearArrayNode::adr_type() const {
2732 Node *adr = in(3);
2733 if (adr == NULL) return NULL; // node is dead
2734 return MemNode::calculate_adr_type(adr->bottom_type());
2735 }
2736
2737 //------------------------------match_edge-------------------------------------
2738 // Do we Match on this edge index or not? Do not match memory
2739 uint ClearArrayNode::match_edge(uint idx) const {
2740 return idx > 1;
2741 }
2742
2743 //------------------------------Identity---------------------------------------
2744 // Clearing a zero length array does nothing
2745 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2746 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2747 }
2748
2749 //------------------------------Idealize---------------------------------------
2750 // Clearing a short array is faster with stores
2751 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2752 // Already know this is a large node, do not try to ideal it
2753 if (!IdealizeClearArrayNode || _is_large) return NULL;
2754
2755 const int unit = BytesPerLong;
2756 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2757 if (!t) return NULL;
2758 if (!t->is_con()) return NULL;
2759 intptr_t raw_count = t->get_con();
2760 intptr_t size = raw_count;
2761 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2762 // Clearing nothing uses the Identity call.
2763 // Negative clears are possible on dead ClearArrays
2764 // (see jck test stmt114.stmt11402.val).
2765 if (size <= 0 || size % unit != 0) return NULL;
2766 intptr_t count = size / unit;
2767 // Length too long; communicate this to matchers and assemblers.
2768 // Assemblers are responsible to produce fast hardware clears for it.
2769 if (size > InitArrayShortSize) {
2770 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2771 }
2772 Node *mem = in(1);
2773 if( phase->type(mem)==Type::TOP ) return NULL;
2774 Node *adr = in(3);
2775 const Type* at = phase->type(adr);
2776 if( at==Type::TOP ) return NULL;
2777 const TypePtr* atp = at->isa_ptr();
2778 // adjust atp to be the correct array element address type
2779 if (atp == NULL) atp = TypePtr::BOTTOM;
2780 else atp = atp->add_offset(Type::OffsetBot);
2781 // Get base for derived pointer purposes
2782 if( adr->Opcode() != Op_AddP ) Unimplemented();
2783 Node *base = adr->in(1);
2784
2785 Node *zero = phase->makecon(TypeLong::ZERO);
2786 Node *off = phase->MakeConX(BytesPerLong);
2787 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2788 count--;
2789 while( count-- ) {
2790 mem = phase->transform(mem);
2791 adr = phase->transform(new AddPNode(base,adr,off));
2792 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2793 }
2794 return mem;
2795 }
2796
2797 //----------------------------step_through----------------------------------
2798 // Return allocation input memory edge if it is different instance
2799 // or itself if it is the one we are looking for.
2800 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2801 Node* n = *np;
2802 assert(n->is_ClearArray(), "sanity");
2803 intptr_t offset;
2804 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2805 // This method is called only before Allocate nodes are expanded
2806 // during macro nodes expansion. Before that ClearArray nodes are
2807 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2808 // Allocate nodes are expanded) which follows allocations.
2809 assert(alloc != NULL, "should have allocation");
2810 if (alloc->_idx == instance_id) {
2811 // Can not bypass initialization of the instance we are looking for.
2812 return false;
2813 }
2814 // Otherwise skip it.
2815 InitializeNode* init = alloc->initialization();
2816 if (init != NULL)
2817 *np = init->in(TypeFunc::Memory);
2818 else
2819 *np = alloc->in(TypeFunc::Memory);
2820 return true;
2821 }
2822
2823 //----------------------------clear_memory-------------------------------------
2824 // Generate code to initialize object storage to zero.
2825 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2826 intptr_t start_offset,
2827 Node* end_offset,
2828 PhaseGVN* phase) {
2829 intptr_t offset = start_offset;
2830
2831 int unit = BytesPerLong;
2832 if ((offset % unit) != 0) {
2833 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2834 adr = phase->transform(adr);
2835 const TypePtr* atp = TypeRawPtr::BOTTOM;
2836 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2837 mem = phase->transform(mem);
2838 offset += BytesPerInt;
2839 }
2840 assert((offset % unit) == 0, "");
2841
2842 // Initialize the remaining stuff, if any, with a ClearArray.
2843 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2844 }
2845
2846 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2847 Node* start_offset,
2848 Node* end_offset,
2849 PhaseGVN* phase) {
2850 if (start_offset == end_offset) {
2851 // nothing to do
2852 return mem;
2853 }
2854
2855 int unit = BytesPerLong;
2856 Node* zbase = start_offset;
2857 Node* zend = end_offset;
2858
2859 // Scale to the unit required by the CPU:
2860 if (!Matcher::init_array_count_is_in_bytes) {
2861 Node* shift = phase->intcon(exact_log2(unit));
2862 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2863 zend = phase->transform(new URShiftXNode(zend, shift) );
2864 }
2865
2866 // Bulk clear double-words
2867 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2868 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2869 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
2870 return phase->transform(mem);
2871 }
2872
2873 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2874 intptr_t start_offset,
2875 intptr_t end_offset,
2876 PhaseGVN* phase) {
2877 if (start_offset == end_offset) {
2878 // nothing to do
2879 return mem;
2880 }
2881
2882 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2883 intptr_t done_offset = end_offset;
2884 if ((done_offset % BytesPerLong) != 0) {
2885 done_offset -= BytesPerInt;
2886 }
2887 if (done_offset > start_offset) {
2888 mem = clear_memory(ctl, mem, dest,
2889 start_offset, phase->MakeConX(done_offset), phase);
2890 }
2891 if (done_offset < end_offset) { // emit the final 32-bit store
2892 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2893 adr = phase->transform(adr);
2894 const TypePtr* atp = TypeRawPtr::BOTTOM;
2895 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2896 mem = phase->transform(mem);
2897 done_offset += BytesPerInt;
2898 }
2899 assert(done_offset == end_offset, "");
2900 return mem;
2901 }
2902
2903 //=============================================================================
2904 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2905 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2906 _adr_type(C->get_adr_type(alias_idx))
2907 {
2908 init_class_id(Class_MemBar);
2909 Node* top = C->top();
2910 init_req(TypeFunc::I_O,top);
2911 init_req(TypeFunc::FramePtr,top);
2912 init_req(TypeFunc::ReturnAdr,top);
2913 if (precedent != NULL)
2914 init_req(TypeFunc::Parms, precedent);
2915 }
2916
2917 //------------------------------cmp--------------------------------------------
2918 uint MemBarNode::hash() const { return NO_HASH; }
2919 uint MemBarNode::cmp( const Node &n ) const {
2920 return (&n == this); // Always fail except on self
2921 }
2922
2923 //------------------------------make-------------------------------------------
2924 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2925 switch (opcode) {
2926 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2927 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2928 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2929 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2930 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2931 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2932 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2933 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2934 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
2935 case Op_Initialize: return new InitializeNode(C, atp, pn);
2936 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2937 default: ShouldNotReachHere(); return NULL;
2938 }
2939 }
2940
2941 //------------------------------Ideal------------------------------------------
2942 // Return a node which is more "ideal" than the current node. Strip out
2943 // control copies
2944 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2945 if (remove_dead_region(phase, can_reshape)) return this;
2946 // Don't bother trying to transform a dead node
2947 if (in(0) && in(0)->is_top()) {
2948 return NULL;
2949 }
2950
2951 bool progress = false;
2952 // Eliminate volatile MemBars for scalar replaced objects.
2953 if (can_reshape && req() == (Precedent+1)) {
2954 bool eliminate = false;
2955 int opc = Opcode();
2956 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2957 // Volatile field loads and stores.
2958 Node* my_mem = in(MemBarNode::Precedent);
2959 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2960 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2961 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2962 // replace this Precedent (decodeN) with the Load instead.
2963 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2964 Node* load_node = my_mem->in(1);
2965 set_req(MemBarNode::Precedent, load_node);
2966 phase->is_IterGVN()->_worklist.push(my_mem);
2967 my_mem = load_node;
2968 } else {
2969 assert(my_mem->unique_out() == this, "sanity");
2970 del_req(Precedent);
2971 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2972 my_mem = NULL;
2973 }
2974 progress = true;
2975 }
2976 if (my_mem != NULL && my_mem->is_Mem()) {
2977 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2978 // Check for scalar replaced object reference.
2979 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2980 t_oop->offset() != Type::OffsetBot &&
2981 t_oop->offset() != Type::OffsetTop) {
2982 eliminate = true;
2983 }
2984 }
2985 } else if (opc == Op_MemBarRelease) {
2986 // Final field stores.
2987 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2988 if ((alloc != NULL) && alloc->is_Allocate() &&
2989 alloc->as_Allocate()->does_not_escape_thread()) {
2990 // The allocated object does not escape.
2991 eliminate = true;
2992 }
2993 }
2994 if (eliminate) {
2995 // Replace MemBar projections by its inputs.
2996 PhaseIterGVN* igvn = phase->is_IterGVN();
2997 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2998 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2999 // Must return either the original node (now dead) or a new node
3000 // (Do not return a top here, since that would break the uniqueness of top.)
3001 return new ConINode(TypeInt::ZERO);
3002 }
3003 }
3004 return progress ? this : NULL;
3005 }
3006
3007 //------------------------------Value------------------------------------------
3008 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3009 if( !in(0) ) return Type::TOP;
3010 if( phase->type(in(0)) == Type::TOP )
3011 return Type::TOP;
3012 return TypeTuple::MEMBAR;
3013 }
3014
3015 //------------------------------match------------------------------------------
3016 // Construct projections for memory.
3017 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3018 switch (proj->_con) {
3019 case TypeFunc::Control:
3020 case TypeFunc::Memory:
3021 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3022 }
3023 ShouldNotReachHere();
3024 return NULL;
3025 }
3026
3027 //===========================InitializeNode====================================
3028 // SUMMARY:
3029 // This node acts as a memory barrier on raw memory, after some raw stores.
3030 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3031 // The Initialize can 'capture' suitably constrained stores as raw inits.
3032 // It can coalesce related raw stores into larger units (called 'tiles').
3033 // It can avoid zeroing new storage for memory units which have raw inits.
3034 // At macro-expansion, it is marked 'complete', and does not optimize further.
3035 //
3036 // EXAMPLE:
3037 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3038 // ctl = incoming control; mem* = incoming memory
3039 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3040 // First allocate uninitialized memory and fill in the header:
3041 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3042 // ctl := alloc.Control; mem* := alloc.Memory*
3043 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3044 // Then initialize to zero the non-header parts of the raw memory block:
3045 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3046 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3047 // After the initialize node executes, the object is ready for service:
3048 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3049 // Suppose its body is immediately initialized as {1,2}:
3050 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3051 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3052 // mem.SLICE(#short[*]) := store2
3053 //
3054 // DETAILS:
3055 // An InitializeNode collects and isolates object initialization after
3056 // an AllocateNode and before the next possible safepoint. As a
3057 // memory barrier (MemBarNode), it keeps critical stores from drifting
3058 // down past any safepoint or any publication of the allocation.
3059 // Before this barrier, a newly-allocated object may have uninitialized bits.
3060 // After this barrier, it may be treated as a real oop, and GC is allowed.
3061 //
3062 // The semantics of the InitializeNode include an implicit zeroing of
3063 // the new object from object header to the end of the object.
3064 // (The object header and end are determined by the AllocateNode.)
3065 //
3066 // Certain stores may be added as direct inputs to the InitializeNode.
3067 // These stores must update raw memory, and they must be to addresses
3068 // derived from the raw address produced by AllocateNode, and with
3069 // a constant offset. They must be ordered by increasing offset.
3070 // The first one is at in(RawStores), the last at in(req()-1).
3071 // Unlike most memory operations, they are not linked in a chain,
3072 // but are displayed in parallel as users of the rawmem output of
3073 // the allocation.
3074 //
3075 // (See comments in InitializeNode::capture_store, which continue
3076 // the example given above.)
3077 //
3078 // When the associated Allocate is macro-expanded, the InitializeNode
3079 // may be rewritten to optimize collected stores. A ClearArrayNode
3080 // may also be created at that point to represent any required zeroing.
3081 // The InitializeNode is then marked 'complete', prohibiting further
3082 // capturing of nearby memory operations.
3083 //
3084 // During macro-expansion, all captured initializations which store
3085 // constant values of 32 bits or smaller are coalesced (if advantageous)
3086 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3087 // initialized in fewer memory operations. Memory words which are
3088 // covered by neither tiles nor non-constant stores are pre-zeroed
3089 // by explicit stores of zero. (The code shape happens to do all
3090 // zeroing first, then all other stores, with both sequences occurring
3091 // in order of ascending offsets.)
3092 //
3093 // Alternatively, code may be inserted between an AllocateNode and its
3094 // InitializeNode, to perform arbitrary initialization of the new object.
3095 // E.g., the object copying intrinsics insert complex data transfers here.
3096 // The initialization must then be marked as 'complete' disable the
3097 // built-in zeroing semantics and the collection of initializing stores.
3098 //
3099 // While an InitializeNode is incomplete, reads from the memory state
3100 // produced by it are optimizable if they match the control edge and
3101 // new oop address associated with the allocation/initialization.
3102 // They return a stored value (if the offset matches) or else zero.
3103 // A write to the memory state, if it matches control and address,
3104 // and if it is to a constant offset, may be 'captured' by the
3105 // InitializeNode. It is cloned as a raw memory operation and rewired
3106 // inside the initialization, to the raw oop produced by the allocation.
3107 // Operations on addresses which are provably distinct (e.g., to
3108 // other AllocateNodes) are allowed to bypass the initialization.
3109 //
3110 // The effect of all this is to consolidate object initialization
3111 // (both arrays and non-arrays, both piecewise and bulk) into a
3112 // single location, where it can be optimized as a unit.
3113 //
3114 // Only stores with an offset less than TrackedInitializationLimit words
3115 // will be considered for capture by an InitializeNode. This puts a
3116 // reasonable limit on the complexity of optimized initializations.
3117
3118 //---------------------------InitializeNode------------------------------------
3119 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3120 : _is_complete(Incomplete), _does_not_escape(false),
3121 MemBarNode(C, adr_type, rawoop)
3122 {
3123 init_class_id(Class_Initialize);
3124
3125 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3126 assert(in(RawAddress) == rawoop, "proper init");
3127 // Note: allocation() can be NULL, for secondary initialization barriers
3128 }
3129
3130 // Since this node is not matched, it will be processed by the
3131 // register allocator. Declare that there are no constraints
3132 // on the allocation of the RawAddress edge.
3133 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3134 // This edge should be set to top, by the set_complete. But be conservative.
3135 if (idx == InitializeNode::RawAddress)
3136 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3137 return RegMask::Empty;
3138 }
3139
3140 Node* InitializeNode::memory(uint alias_idx) {
3141 Node* mem = in(Memory);
3142 if (mem->is_MergeMem()) {
3143 return mem->as_MergeMem()->memory_at(alias_idx);
3144 } else {
3145 // incoming raw memory is not split
3146 return mem;
3147 }
3148 }
3149
3150 bool InitializeNode::is_non_zero() {
3151 if (is_complete()) return false;
3152 remove_extra_zeroes();
3153 return (req() > RawStores);
3154 }
3155
3156 void InitializeNode::set_complete(PhaseGVN* phase) {
3157 assert(!is_complete(), "caller responsibility");
3158 _is_complete = Complete;
3159
3160 // After this node is complete, it contains a bunch of
3161 // raw-memory initializations. There is no need for
3162 // it to have anything to do with non-raw memory effects.
3163 // Therefore, tell all non-raw users to re-optimize themselves,
3164 // after skipping the memory effects of this initialization.
3165 PhaseIterGVN* igvn = phase->is_IterGVN();
3166 if (igvn) igvn->add_users_to_worklist(this);
3167 }
3168
3169 // convenience function
3170 // return false if the init contains any stores already
3171 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3172 InitializeNode* init = initialization();
3173 if (init == NULL || init->is_complete()) return false;
3174 init->remove_extra_zeroes();
3175 // for now, if this allocation has already collected any inits, bail:
3176 if (init->is_non_zero()) return false;
3177 init->set_complete(phase);
3178 return true;
3179 }
3180
3181 void InitializeNode::remove_extra_zeroes() {
3182 if (req() == RawStores) return;
3183 Node* zmem = zero_memory();
3184 uint fill = RawStores;
3185 for (uint i = fill; i < req(); i++) {
3186 Node* n = in(i);
3187 if (n->is_top() || n == zmem) continue; // skip
3188 if (fill < i) set_req(fill, n); // compact
3189 ++fill;
3190 }
3191 // delete any empty spaces created:
3192 while (fill < req()) {
3193 del_req(fill);
3194 }
3195 }
3196
3197 // Helper for remembering which stores go with which offsets.
3198 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3199 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3200 intptr_t offset = -1;
3201 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3202 phase, offset);
3203 if (base == NULL) return -1; // something is dead,
3204 if (offset < 0) return -1; // dead, dead
3205 return offset;
3206 }
3207
3208 // Helper for proving that an initialization expression is
3209 // "simple enough" to be folded into an object initialization.
3210 // Attempts to prove that a store's initial value 'n' can be captured
3211 // within the initialization without creating a vicious cycle, such as:
3212 // { Foo p = new Foo(); p.next = p; }
3213 // True for constants and parameters and small combinations thereof.
3214 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3215 if (n == NULL) return true; // (can this really happen?)
3216 if (n->is_Proj()) n = n->in(0);
3217 if (n == this) return false; // found a cycle
3218 if (n->is_Con()) return true;
3219 if (n->is_Start()) return true; // params, etc., are OK
3220 if (n->is_Root()) return true; // even better
3221
3222 Node* ctl = n->in(0);
3223 if (ctl != NULL && !ctl->is_top()) {
3224 if (ctl->is_Proj()) ctl = ctl->in(0);
3225 if (ctl == this) return false;
3226
3227 // If we already know that the enclosing memory op is pinned right after
3228 // the init, then any control flow that the store has picked up
3229 // must have preceded the init, or else be equal to the init.
3230 // Even after loop optimizations (which might change control edges)
3231 // a store is never pinned *before* the availability of its inputs.
3232 if (!MemNode::all_controls_dominate(n, this))
3233 return false; // failed to prove a good control
3234 }
3235
3236 // Check data edges for possible dependencies on 'this'.
3237 if ((count += 1) > 20) return false; // complexity limit
3238 for (uint i = 1; i < n->req(); i++) {
3239 Node* m = n->in(i);
3240 if (m == NULL || m == n || m->is_top()) continue;
3241 uint first_i = n->find_edge(m);
3242 if (i != first_i) continue; // process duplicate edge just once
3243 if (!detect_init_independence(m, count)) {
3244 return false;
3245 }
3246 }
3247
3248 return true;
3249 }
3250
3251 // Here are all the checks a Store must pass before it can be moved into
3252 // an initialization. Returns zero if a check fails.
3253 // On success, returns the (constant) offset to which the store applies,
3254 // within the initialized memory.
3255 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3256 const int FAIL = 0;
3257 if (st->is_unaligned_access()) {
3258 return FAIL;
3259 }
3260 if (st->req() != MemNode::ValueIn + 1)
3261 return FAIL; // an inscrutable StoreNode (card mark?)
3262 Node* ctl = st->in(MemNode::Control);
3263 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3264 return FAIL; // must be unconditional after the initialization
3265 Node* mem = st->in(MemNode::Memory);
3266 if (!(mem->is_Proj() && mem->in(0) == this))
3267 return FAIL; // must not be preceded by other stores
3268 Node* adr = st->in(MemNode::Address);
3269 intptr_t offset;
3270 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3271 if (alloc == NULL)
3272 return FAIL; // inscrutable address
3273 if (alloc != allocation())
3274 return FAIL; // wrong allocation! (store needs to float up)
3275 Node* val = st->in(MemNode::ValueIn);
3276 int complexity_count = 0;
3277 if (!detect_init_independence(val, complexity_count))
3278 return FAIL; // stored value must be 'simple enough'
3279
3280 // The Store can be captured only if nothing after the allocation
3281 // and before the Store is using the memory location that the store
3282 // overwrites.
3283 bool failed = false;
3284 // If is_complete_with_arraycopy() is true the shape of the graph is
3285 // well defined and is safe so no need for extra checks.
3286 if (!is_complete_with_arraycopy()) {
3287 // We are going to look at each use of the memory state following
3288 // the allocation to make sure nothing reads the memory that the
3289 // Store writes.
3290 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3291 int alias_idx = phase->C->get_alias_index(t_adr);
3292 ResourceMark rm;
3293 Unique_Node_List mems;
3294 mems.push(mem);
3295 Node* unique_merge = NULL;
3296 for (uint next = 0; next < mems.size(); ++next) {
3297 Node *m = mems.at(next);
3298 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3299 Node *n = m->fast_out(j);
3300 if (n->outcnt() == 0) {
3301 continue;
3302 }
3303 if (n == st) {
3304 continue;
3305 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3306 // If the control of this use is different from the control
3307 // of the Store which is right after the InitializeNode then
3308 // this node cannot be between the InitializeNode and the
3309 // Store.
3310 continue;
3311 } else if (n->is_MergeMem()) {
3312 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3313 // We can hit a MergeMemNode (that will likely go away
3314 // later) that is a direct use of the memory state
3315 // following the InitializeNode on the same slice as the
3316 // store node that we'd like to capture. We need to check
3317 // the uses of the MergeMemNode.
3318 mems.push(n);
3319 }
3320 } else if (n->is_Mem()) {
3321 Node* other_adr = n->in(MemNode::Address);
3322 if (other_adr == adr) {
3323 failed = true;
3324 break;
3325 } else {
3326 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3327 if (other_t_adr != NULL) {
3328 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3329 if (other_alias_idx == alias_idx) {
3330 // A load from the same memory slice as the store right
3331 // after the InitializeNode. We check the control of the
3332 // object/array that is loaded from. If it's the same as
3333 // the store control then we cannot capture the store.
3334 assert(!n->is_Store(), "2 stores to same slice on same control?");
3335 Node* base = other_adr;
3336 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3337 base = base->in(AddPNode::Base);
3338 if (base != NULL) {
3339 base = base->uncast();
3340 if (base->is_Proj() && base->in(0) == alloc) {
3341 failed = true;
3342 break;
3343 }
3344 }
3345 }
3346 }
3347 }
3348 } else {
3349 failed = true;
3350 break;
3351 }
3352 }
3353 }
3354 }
3355 if (failed) {
3356 if (!can_reshape) {
3357 // We decided we couldn't capture the store during parsing. We
3358 // should try again during the next IGVN once the graph is
3359 // cleaner.
3360 phase->C->record_for_igvn(st);
3361 }
3362 return FAIL;
3363 }
3364
3365 return offset; // success
3366 }
3367
3368 // Find the captured store in(i) which corresponds to the range
3369 // [start..start+size) in the initialized object.
3370 // If there is one, return its index i. If there isn't, return the
3371 // negative of the index where it should be inserted.
3372 // Return 0 if the queried range overlaps an initialization boundary
3373 // or if dead code is encountered.
3374 // If size_in_bytes is zero, do not bother with overlap checks.
3375 int InitializeNode::captured_store_insertion_point(intptr_t start,
3376 int size_in_bytes,
3377 PhaseTransform* phase) {
3378 const int FAIL = 0, MAX_STORE = BytesPerLong;
3379
3380 if (is_complete())
3381 return FAIL; // arraycopy got here first; punt
3382
3383 assert(allocation() != NULL, "must be present");
3384
3385 // no negatives, no header fields:
3386 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3387
3388 // after a certain size, we bail out on tracking all the stores:
3389 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3390 if (start >= ti_limit) return FAIL;
3391
3392 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3393 if (i >= limit) return -(int)i; // not found; here is where to put it
3394
3395 Node* st = in(i);
3396 intptr_t st_off = get_store_offset(st, phase);
3397 if (st_off < 0) {
3398 if (st != zero_memory()) {
3399 return FAIL; // bail out if there is dead garbage
3400 }
3401 } else if (st_off > start) {
3402 // ...we are done, since stores are ordered
3403 if (st_off < start + size_in_bytes) {
3404 return FAIL; // the next store overlaps
3405 }
3406 return -(int)i; // not found; here is where to put it
3407 } else if (st_off < start) {
3408 if (size_in_bytes != 0 &&
3409 start < st_off + MAX_STORE &&
3410 start < st_off + st->as_Store()->memory_size()) {
3411 return FAIL; // the previous store overlaps
3412 }
3413 } else {
3414 if (size_in_bytes != 0 &&
3415 st->as_Store()->memory_size() != size_in_bytes) {
3416 return FAIL; // mismatched store size
3417 }
3418 return i;
3419 }
3420
3421 ++i;
3422 }
3423 }
3424
3425 // Look for a captured store which initializes at the offset 'start'
3426 // with the given size. If there is no such store, and no other
3427 // initialization interferes, then return zero_memory (the memory
3428 // projection of the AllocateNode).
3429 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3430 PhaseTransform* phase) {
3431 assert(stores_are_sane(phase), "");
3432 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3433 if (i == 0) {
3434 return NULL; // something is dead
3435 } else if (i < 0) {
3436 return zero_memory(); // just primordial zero bits here
3437 } else {
3438 Node* st = in(i); // here is the store at this position
3439 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3440 return st;
3441 }
3442 }
3443
3444 // Create, as a raw pointer, an address within my new object at 'offset'.
3445 Node* InitializeNode::make_raw_address(intptr_t offset,
3446 PhaseTransform* phase) {
3447 Node* addr = in(RawAddress);
3448 if (offset != 0) {
3449 Compile* C = phase->C;
3450 addr = phase->transform( new AddPNode(C->top(), addr,
3451 phase->MakeConX(offset)) );
3452 }
3453 return addr;
3454 }
3455
3456 // Clone the given store, converting it into a raw store
3457 // initializing a field or element of my new object.
3458 // Caller is responsible for retiring the original store,
3459 // with subsume_node or the like.
3460 //
3461 // From the example above InitializeNode::InitializeNode,
3462 // here are the old stores to be captured:
3463 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3464 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3465 //
3466 // Here is the changed code; note the extra edges on init:
3467 // alloc = (Allocate ...)
3468 // rawoop = alloc.RawAddress
3469 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3470 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3471 // init = (Initialize alloc.Control alloc.Memory rawoop
3472 // rawstore1 rawstore2)
3473 //
3474 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3475 PhaseTransform* phase, bool can_reshape) {
3476 assert(stores_are_sane(phase), "");
3477
3478 if (start < 0) return NULL;
3479 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3480
3481 Compile* C = phase->C;
3482 int size_in_bytes = st->memory_size();
3483 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3484 if (i == 0) return NULL; // bail out
3485 Node* prev_mem = NULL; // raw memory for the captured store
3486 if (i > 0) {
3487 prev_mem = in(i); // there is a pre-existing store under this one
3488 set_req(i, C->top()); // temporarily disconnect it
3489 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3490 } else {
3491 i = -i; // no pre-existing store
3492 prev_mem = zero_memory(); // a slice of the newly allocated object
3493 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3494 set_req(--i, C->top()); // reuse this edge; it has been folded away
3495 else
3496 ins_req(i, C->top()); // build a new edge
3497 }
3498 Node* new_st = st->clone();
3499 new_st->set_req(MemNode::Control, in(Control));
3500 new_st->set_req(MemNode::Memory, prev_mem);
3501 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3502 new_st = phase->transform(new_st);
3503
3504 // At this point, new_st might have swallowed a pre-existing store
3505 // at the same offset, or perhaps new_st might have disappeared,
3506 // if it redundantly stored the same value (or zero to fresh memory).
3507
3508 // In any case, wire it in:
3509 phase->igvn_rehash_node_delayed(this);
3510 set_req(i, new_st);
3511
3512 // The caller may now kill the old guy.
3513 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3514 assert(check_st == new_st || check_st == NULL, "must be findable");
3515 assert(!is_complete(), "");
3516 return new_st;
3517 }
3518
3519 static bool store_constant(jlong* tiles, int num_tiles,
3520 intptr_t st_off, int st_size,
3521 jlong con) {
3522 if ((st_off & (st_size-1)) != 0)
3523 return false; // strange store offset (assume size==2**N)
3524 address addr = (address)tiles + st_off;
3525 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3526 switch (st_size) {
3527 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3528 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3529 case sizeof(jint): *(jint*) addr = (jint) con; break;
3530 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3531 default: return false; // strange store size (detect size!=2**N here)
3532 }
3533 return true; // return success to caller
3534 }
3535
3536 // Coalesce subword constants into int constants and possibly
3537 // into long constants. The goal, if the CPU permits,
3538 // is to initialize the object with a small number of 64-bit tiles.
3539 // Also, convert floating-point constants to bit patterns.
3540 // Non-constants are not relevant to this pass.
3541 //
3542 // In terms of the running example on InitializeNode::InitializeNode
3543 // and InitializeNode::capture_store, here is the transformation
3544 // of rawstore1 and rawstore2 into rawstore12:
3545 // alloc = (Allocate ...)
3546 // rawoop = alloc.RawAddress
3547 // tile12 = 0x00010002
3548 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3549 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3550 //
3551 void
3552 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3553 Node* size_in_bytes,
3554 PhaseGVN* phase) {
3555 Compile* C = phase->C;
3556
3557 assert(stores_are_sane(phase), "");
3558 // Note: After this pass, they are not completely sane,
3559 // since there may be some overlaps.
3560
3561 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3562
3563 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3564 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3565 size_limit = MIN2(size_limit, ti_limit);
3566 size_limit = align_size_up(size_limit, BytesPerLong);
3567 int num_tiles = size_limit / BytesPerLong;
3568
3569 // allocate space for the tile map:
3570 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3571 jlong tiles_buf[small_len];
3572 Node* nodes_buf[small_len];
3573 jlong inits_buf[small_len];
3574 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3575 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3576 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3577 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3578 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3579 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3580 // tiles: exact bitwise model of all primitive constants
3581 // nodes: last constant-storing node subsumed into the tiles model
3582 // inits: which bytes (in each tile) are touched by any initializations
3583
3584 //// Pass A: Fill in the tile model with any relevant stores.
3585
3586 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3587 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3588 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3589 Node* zmem = zero_memory(); // initially zero memory state
3590 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3591 Node* st = in(i);
3592 intptr_t st_off = get_store_offset(st, phase);
3593
3594 // Figure out the store's offset and constant value:
3595 if (st_off < header_size) continue; //skip (ignore header)
3596 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3597 int st_size = st->as_Store()->memory_size();
3598 if (st_off + st_size > size_limit) break;
3599
3600 // Record which bytes are touched, whether by constant or not.
3601 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3602 continue; // skip (strange store size)
3603
3604 const Type* val = phase->type(st->in(MemNode::ValueIn));
3605 if (!val->singleton()) continue; //skip (non-con store)
3606 BasicType type = val->basic_type();
3607
3608 jlong con = 0;
3609 switch (type) {
3610 case T_INT: con = val->is_int()->get_con(); break;
3611 case T_LONG: con = val->is_long()->get_con(); break;
3612 case T_FLOAT: con = jint_cast(val->getf()); break;
3613 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3614 default: continue; //skip (odd store type)
3615 }
3616
3617 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3618 st->Opcode() == Op_StoreL) {
3619 continue; // This StoreL is already optimal.
3620 }
3621
3622 // Store down the constant.
3623 store_constant(tiles, num_tiles, st_off, st_size, con);
3624
3625 intptr_t j = st_off >> LogBytesPerLong;
3626
3627 if (type == T_INT && st_size == BytesPerInt
3628 && (st_off & BytesPerInt) == BytesPerInt) {
3629 jlong lcon = tiles[j];
3630 if (!Matcher::isSimpleConstant64(lcon) &&
3631 st->Opcode() == Op_StoreI) {
3632 // This StoreI is already optimal by itself.
3633 jint* intcon = (jint*) &tiles[j];
3634 intcon[1] = 0; // undo the store_constant()
3635
3636 // If the previous store is also optimal by itself, back up and
3637 // undo the action of the previous loop iteration... if we can.
3638 // But if we can't, just let the previous half take care of itself.
3639 st = nodes[j];
3640 st_off -= BytesPerInt;
3641 con = intcon[0];
3642 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3643 assert(st_off >= header_size, "still ignoring header");
3644 assert(get_store_offset(st, phase) == st_off, "must be");
3645 assert(in(i-1) == zmem, "must be");
3646 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3647 assert(con == tcon->is_int()->get_con(), "must be");
3648 // Undo the effects of the previous loop trip, which swallowed st:
3649 intcon[0] = 0; // undo store_constant()
3650 set_req(i-1, st); // undo set_req(i, zmem)
3651 nodes[j] = NULL; // undo nodes[j] = st
3652 --old_subword; // undo ++old_subword
3653 }
3654 continue; // This StoreI is already optimal.
3655 }
3656 }
3657
3658 // This store is not needed.
3659 set_req(i, zmem);
3660 nodes[j] = st; // record for the moment
3661 if (st_size < BytesPerLong) // something has changed
3662 ++old_subword; // includes int/float, but who's counting...
3663 else ++old_long;
3664 }
3665
3666 if ((old_subword + old_long) == 0)
3667 return; // nothing more to do
3668
3669 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3670 // Be sure to insert them before overlapping non-constant stores.
3671 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3672 for (int j = 0; j < num_tiles; j++) {
3673 jlong con = tiles[j];
3674 jlong init = inits[j];
3675 if (con == 0) continue;
3676 jint con0, con1; // split the constant, address-wise
3677 jint init0, init1; // split the init map, address-wise
3678 { union { jlong con; jint intcon[2]; } u;
3679 u.con = con;
3680 con0 = u.intcon[0];
3681 con1 = u.intcon[1];
3682 u.con = init;
3683 init0 = u.intcon[0];
3684 init1 = u.intcon[1];
3685 }
3686
3687 Node* old = nodes[j];
3688 assert(old != NULL, "need the prior store");
3689 intptr_t offset = (j * BytesPerLong);
3690
3691 bool split = !Matcher::isSimpleConstant64(con);
3692
3693 if (offset < header_size) {
3694 assert(offset + BytesPerInt >= header_size, "second int counts");
3695 assert(*(jint*)&tiles[j] == 0, "junk in header");
3696 split = true; // only the second word counts
3697 // Example: int a[] = { 42 ... }
3698 } else if (con0 == 0 && init0 == -1) {
3699 split = true; // first word is covered by full inits
3700 // Example: int a[] = { ... foo(), 42 ... }
3701 } else if (con1 == 0 && init1 == -1) {
3702 split = true; // second word is covered by full inits
3703 // Example: int a[] = { ... 42, foo() ... }
3704 }
3705
3706 // Here's a case where init0 is neither 0 nor -1:
3707 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3708 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3709 // In this case the tile is not split; it is (jlong)42.
3710 // The big tile is stored down, and then the foo() value is inserted.
3711 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3712
3713 Node* ctl = old->in(MemNode::Control);
3714 Node* adr = make_raw_address(offset, phase);
3715 const TypePtr* atp = TypeRawPtr::BOTTOM;
3716
3717 // One or two coalesced stores to plop down.
3718 Node* st[2];
3719 intptr_t off[2];
3720 int nst = 0;
3721 if (!split) {
3722 ++new_long;
3723 off[nst] = offset;
3724 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3725 phase->longcon(con), T_LONG, MemNode::unordered);
3726 } else {
3727 // Omit either if it is a zero.
3728 if (con0 != 0) {
3729 ++new_int;
3730 off[nst] = offset;
3731 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3732 phase->intcon(con0), T_INT, MemNode::unordered);
3733 }
3734 if (con1 != 0) {
3735 ++new_int;
3736 offset += BytesPerInt;
3737 adr = make_raw_address(offset, phase);
3738 off[nst] = offset;
3739 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3740 phase->intcon(con1), T_INT, MemNode::unordered);
3741 }
3742 }
3743
3744 // Insert second store first, then the first before the second.
3745 // Insert each one just before any overlapping non-constant stores.
3746 while (nst > 0) {
3747 Node* st1 = st[--nst];
3748 C->copy_node_notes_to(st1, old);
3749 st1 = phase->transform(st1);
3750 offset = off[nst];
3751 assert(offset >= header_size, "do not smash header");
3752 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3753 guarantee(ins_idx != 0, "must re-insert constant store");
3754 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3755 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3756 set_req(--ins_idx, st1);
3757 else
3758 ins_req(ins_idx, st1);
3759 }
3760 }
3761
3762 if (PrintCompilation && WizardMode)
3763 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3764 old_subword, old_long, new_int, new_long);
3765 if (C->log() != NULL)
3766 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3767 old_subword, old_long, new_int, new_long);
3768
3769 // Clean up any remaining occurrences of zmem:
3770 remove_extra_zeroes();
3771 }
3772
3773 // Explore forward from in(start) to find the first fully initialized
3774 // word, and return its offset. Skip groups of subword stores which
3775 // together initialize full words. If in(start) is itself part of a
3776 // fully initialized word, return the offset of in(start). If there
3777 // are no following full-word stores, or if something is fishy, return
3778 // a negative value.
3779 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3780 int int_map = 0;
3781 intptr_t int_map_off = 0;
3782 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3783
3784 for (uint i = start, limit = req(); i < limit; i++) {
3785 Node* st = in(i);
3786
3787 intptr_t st_off = get_store_offset(st, phase);
3788 if (st_off < 0) break; // return conservative answer
3789
3790 int st_size = st->as_Store()->memory_size();
3791 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3792 return st_off; // we found a complete word init
3793 }
3794
3795 // update the map:
3796
3797 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3798 if (this_int_off != int_map_off) {
3799 // reset the map:
3800 int_map = 0;
3801 int_map_off = this_int_off;
3802 }
3803
3804 int subword_off = st_off - this_int_off;
3805 int_map |= right_n_bits(st_size) << subword_off;
3806 if ((int_map & FULL_MAP) == FULL_MAP) {
3807 return this_int_off; // we found a complete word init
3808 }
3809
3810 // Did this store hit or cross the word boundary?
3811 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3812 if (next_int_off == this_int_off + BytesPerInt) {
3813 // We passed the current int, without fully initializing it.
3814 int_map_off = next_int_off;
3815 int_map >>= BytesPerInt;
3816 } else if (next_int_off > this_int_off + BytesPerInt) {
3817 // We passed the current and next int.
3818 return this_int_off + BytesPerInt;
3819 }
3820 }
3821
3822 return -1;
3823 }
3824
3825
3826 // Called when the associated AllocateNode is expanded into CFG.
3827 // At this point, we may perform additional optimizations.
3828 // Linearize the stores by ascending offset, to make memory
3829 // activity as coherent as possible.
3830 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3831 intptr_t header_size,
3832 Node* size_in_bytes,
3833 PhaseGVN* phase) {
3834 assert(!is_complete(), "not already complete");
3835 assert(stores_are_sane(phase), "");
3836 assert(allocation() != NULL, "must be present");
3837
3838 remove_extra_zeroes();
3839
3840 if (ReduceFieldZeroing || ReduceBulkZeroing)
3841 // reduce instruction count for common initialization patterns
3842 coalesce_subword_stores(header_size, size_in_bytes, phase);
3843
3844 Node* zmem = zero_memory(); // initially zero memory state
3845 Node* inits = zmem; // accumulating a linearized chain of inits
3846 #ifdef ASSERT
3847 intptr_t first_offset = allocation()->minimum_header_size();
3848 intptr_t last_init_off = first_offset; // previous init offset
3849 intptr_t last_init_end = first_offset; // previous init offset+size
3850 intptr_t last_tile_end = first_offset; // previous tile offset+size
3851 #endif
3852 intptr_t zeroes_done = header_size;
3853
3854 bool do_zeroing = true; // we might give up if inits are very sparse
3855 int big_init_gaps = 0; // how many large gaps have we seen?
3856
3857 if (UseTLAB && ZeroTLAB) do_zeroing = false;
3858 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3859
3860 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3861 Node* st = in(i);
3862 intptr_t st_off = get_store_offset(st, phase);
3863 if (st_off < 0)
3864 break; // unknown junk in the inits
3865 if (st->in(MemNode::Memory) != zmem)
3866 break; // complicated store chains somehow in list
3867
3868 int st_size = st->as_Store()->memory_size();
3869 intptr_t next_init_off = st_off + st_size;
3870
3871 if (do_zeroing && zeroes_done < next_init_off) {
3872 // See if this store needs a zero before it or under it.
3873 intptr_t zeroes_needed = st_off;
3874
3875 if (st_size < BytesPerInt) {
3876 // Look for subword stores which only partially initialize words.
3877 // If we find some, we must lay down some word-level zeroes first,
3878 // underneath the subword stores.
3879 //
3880 // Examples:
3881 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3882 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3883 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3884 //
3885 // Note: coalesce_subword_stores may have already done this,
3886 // if it was prompted by constant non-zero subword initializers.
3887 // But this case can still arise with non-constant stores.
3888
3889 intptr_t next_full_store = find_next_fullword_store(i, phase);
3890
3891 // In the examples above:
3892 // in(i) p q r s x y z
3893 // st_off 12 13 14 15 12 13 14
3894 // st_size 1 1 1 1 1 1 1
3895 // next_full_s. 12 16 16 16 16 16 16
3896 // z's_done 12 16 16 16 12 16 12
3897 // z's_needed 12 16 16 16 16 16 16
3898 // zsize 0 0 0 0 4 0 4
3899 if (next_full_store < 0) {
3900 // Conservative tack: Zero to end of current word.
3901 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3902 } else {
3903 // Zero to beginning of next fully initialized word.
3904 // Or, don't zero at all, if we are already in that word.
3905 assert(next_full_store >= zeroes_needed, "must go forward");
3906 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3907 zeroes_needed = next_full_store;
3908 }
3909 }
3910
3911 if (zeroes_needed > zeroes_done) {
3912 intptr_t zsize = zeroes_needed - zeroes_done;
3913 // Do some incremental zeroing on rawmem, in parallel with inits.
3914 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3915 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3916 zeroes_done, zeroes_needed,
3917 phase);
3918 zeroes_done = zeroes_needed;
3919 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
3920 do_zeroing = false; // leave the hole, next time
3921 }
3922 }
3923
3924 // Collect the store and move on:
3925 st->set_req(MemNode::Memory, inits);
3926 inits = st; // put it on the linearized chain
3927 set_req(i, zmem); // unhook from previous position
3928
3929 if (zeroes_done == st_off)
3930 zeroes_done = next_init_off;
3931
3932 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3933
3934 #ifdef ASSERT
3935 // Various order invariants. Weaker than stores_are_sane because
3936 // a large constant tile can be filled in by smaller non-constant stores.
3937 assert(st_off >= last_init_off, "inits do not reverse");
3938 last_init_off = st_off;
3939 const Type* val = NULL;
3940 if (st_size >= BytesPerInt &&
3941 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3942 (int)val->basic_type() < (int)T_OBJECT) {
3943 assert(st_off >= last_tile_end, "tiles do not overlap");
3944 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3945 last_tile_end = MAX2(last_tile_end, next_init_off);
3946 } else {
3947 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3948 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3949 assert(st_off >= last_init_end, "inits do not overlap");
3950 last_init_end = next_init_off; // it's a non-tile
3951 }
3952 #endif //ASSERT
3953 }
3954
3955 remove_extra_zeroes(); // clear out all the zmems left over
3956 add_req(inits);
3957
3958 if (!(UseTLAB && ZeroTLAB)) {
3959 // If anything remains to be zeroed, zero it all now.
3960 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3961 // if it is the last unused 4 bytes of an instance, forget about it
3962 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3963 if (zeroes_done + BytesPerLong >= size_limit) {
3964 AllocateNode* alloc = allocation();
3965 assert(alloc != NULL, "must be present");
3966 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
3967 Node* klass_node = alloc->in(AllocateNode::KlassNode);
3968 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3969 if (zeroes_done == k->layout_helper())
3970 zeroes_done = size_limit;
3971 }
3972 }
3973 if (zeroes_done < size_limit) {
3974 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3975 zeroes_done, size_in_bytes, phase);
3976 }
3977 }
3978
3979 set_complete(phase);
3980 return rawmem;
3981 }
3982
3983
3984 #ifdef ASSERT
3985 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3986 if (is_complete())
3987 return true; // stores could be anything at this point
3988 assert(allocation() != NULL, "must be present");
3989 intptr_t last_off = allocation()->minimum_header_size();
3990 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3991 Node* st = in(i);
3992 intptr_t st_off = get_store_offset(st, phase);
3993 if (st_off < 0) continue; // ignore dead garbage
3994 if (last_off > st_off) {
3995 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3996 this->dump(2);
3997 assert(false, "ascending store offsets");
3998 return false;
3999 }
4000 last_off = st_off + st->as_Store()->memory_size();
4001 }
4002 return true;
4003 }
4004 #endif //ASSERT
4005
4006
4007
4008
4009 //============================MergeMemNode=====================================
4010 //
4011 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4012 // contributing store or call operations. Each contributor provides the memory
4013 // state for a particular "alias type" (see Compile::alias_type). For example,
4014 // if a MergeMem has an input X for alias category #6, then any memory reference
4015 // to alias category #6 may use X as its memory state input, as an exact equivalent
4016 // to using the MergeMem as a whole.
4017 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4018 //
4019 // (Here, the <N> notation gives the index of the relevant adr_type.)
4020 //
4021 // In one special case (and more cases in the future), alias categories overlap.
4022 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4023 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4024 // it is exactly equivalent to that state W:
4025 // MergeMem(<Bot>: W) <==> W
4026 //
4027 // Usually, the merge has more than one input. In that case, where inputs
4028 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4029 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4030 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4031 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4032 //
4033 // A merge can take a "wide" memory state as one of its narrow inputs.
4034 // This simply means that the merge observes out only the relevant parts of
4035 // the wide input. That is, wide memory states arriving at narrow merge inputs
4036 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4037 //
4038 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4039 // and that memory slices "leak through":
4040 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4041 //
4042 // But, in such a cascade, repeated memory slices can "block the leak":
4043 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4044 //
4045 // In the last example, Y is not part of the combined memory state of the
4046 // outermost MergeMem. The system must, of course, prevent unschedulable
4047 // memory states from arising, so you can be sure that the state Y is somehow
4048 // a precursor to state Y'.
4049 //
4050 //
4051 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4052 // of each MergeMemNode array are exactly the numerical alias indexes, including
4053 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4054 // Compile::alias_type (and kin) produce and manage these indexes.
4055 //
4056 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4057 // (Note that this provides quick access to the top node inside MergeMem methods,
4058 // without the need to reach out via TLS to Compile::current.)
4059 //
4060 // As a consequence of what was just described, a MergeMem that represents a full
4061 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4062 // containing all alias categories.
4063 //
4064 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4065 //
4066 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4067 // a memory state for the alias type <N>, or else the top node, meaning that
4068 // there is no particular input for that alias type. Note that the length of
4069 // a MergeMem is variable, and may be extended at any time to accommodate new
4070 // memory states at larger alias indexes. When merges grow, they are of course
4071 // filled with "top" in the unused in() positions.
4072 //
4073 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4074 // (Top was chosen because it works smoothly with passes like GCM.)
4075 //
4076 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4077 // the type of random VM bits like TLS references.) Since it is always the
4078 // first non-Bot memory slice, some low-level loops use it to initialize an
4079 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4080 //
4081 //
4082 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4083 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4084 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4085 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4086 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4087 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4088 //
4089 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4090 // really that different from the other memory inputs. An abbreviation called
4091 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4092 //
4093 //
4094 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4095 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4096 // that "emerges though" the base memory will be marked as excluding the alias types
4097 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4098 //
4099 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4100 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4101 //
4102 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4103 // (It is currently unimplemented.) As you can see, the resulting merge is
4104 // actually a disjoint union of memory states, rather than an overlay.
4105 //
4106
4107 //------------------------------MergeMemNode-----------------------------------
4108 Node* MergeMemNode::make_empty_memory() {
4109 Node* empty_memory = (Node*) Compile::current()->top();
4110 assert(empty_memory->is_top(), "correct sentinel identity");
4111 return empty_memory;
4112 }
4113
4114 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4115 init_class_id(Class_MergeMem);
4116 // all inputs are nullified in Node::Node(int)
4117 // set_input(0, NULL); // no control input
4118
4119 // Initialize the edges uniformly to top, for starters.
4120 Node* empty_mem = make_empty_memory();
4121 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4122 init_req(i,empty_mem);
4123 }
4124 assert(empty_memory() == empty_mem, "");
4125
4126 if( new_base != NULL && new_base->is_MergeMem() ) {
4127 MergeMemNode* mdef = new_base->as_MergeMem();
4128 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4129 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4130 mms.set_memory(mms.memory2());
4131 }
4132 assert(base_memory() == mdef->base_memory(), "");
4133 } else {
4134 set_base_memory(new_base);
4135 }
4136 }
4137
4138 // Make a new, untransformed MergeMem with the same base as 'mem'.
4139 // If mem is itself a MergeMem, populate the result with the same edges.
4140 MergeMemNode* MergeMemNode::make(Node* mem) {
4141 return new MergeMemNode(mem);
4142 }
4143
4144 //------------------------------cmp--------------------------------------------
4145 uint MergeMemNode::hash() const { return NO_HASH; }
4146 uint MergeMemNode::cmp( const Node &n ) const {
4147 return (&n == this); // Always fail except on self
4148 }
4149
4150 //------------------------------Identity---------------------------------------
4151 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4152 // Identity if this merge point does not record any interesting memory
4153 // disambiguations.
4154 Node* base_mem = base_memory();
4155 Node* empty_mem = empty_memory();
4156 if (base_mem != empty_mem) { // Memory path is not dead?
4157 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4158 Node* mem = in(i);
4159 if (mem != empty_mem && mem != base_mem) {
4160 return this; // Many memory splits; no change
4161 }
4162 }
4163 }
4164 return base_mem; // No memory splits; ID on the one true input
4165 }
4166
4167 //------------------------------Ideal------------------------------------------
4168 // This method is invoked recursively on chains of MergeMem nodes
4169 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4170 // Remove chain'd MergeMems
4171 //
4172 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4173 // relative to the "in(Bot)". Since we are patching both at the same time,
4174 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4175 // but rewrite each "in(i)" relative to the new "in(Bot)".
4176 Node *progress = NULL;
4177
4178
4179 Node* old_base = base_memory();
4180 Node* empty_mem = empty_memory();
4181 if (old_base == empty_mem)
4182 return NULL; // Dead memory path.
4183
4184 MergeMemNode* old_mbase;
4185 if (old_base != NULL && old_base->is_MergeMem())
4186 old_mbase = old_base->as_MergeMem();
4187 else
4188 old_mbase = NULL;
4189 Node* new_base = old_base;
4190
4191 // simplify stacked MergeMems in base memory
4192 if (old_mbase) new_base = old_mbase->base_memory();
4193
4194 // the base memory might contribute new slices beyond my req()
4195 if (old_mbase) grow_to_match(old_mbase);
4196
4197 // Look carefully at the base node if it is a phi.
4198 PhiNode* phi_base;
4199 if (new_base != NULL && new_base->is_Phi())
4200 phi_base = new_base->as_Phi();
4201 else
4202 phi_base = NULL;
4203
4204 Node* phi_reg = NULL;
4205 uint phi_len = (uint)-1;
4206 if (phi_base != NULL && !phi_base->is_copy()) {
4207 // do not examine phi if degraded to a copy
4208 phi_reg = phi_base->region();
4209 phi_len = phi_base->req();
4210 // see if the phi is unfinished
4211 for (uint i = 1; i < phi_len; i++) {
4212 if (phi_base->in(i) == NULL) {
4213 // incomplete phi; do not look at it yet!
4214 phi_reg = NULL;
4215 phi_len = (uint)-1;
4216 break;
4217 }
4218 }
4219 }
4220
4221 // Note: We do not call verify_sparse on entry, because inputs
4222 // can normalize to the base_memory via subsume_node or similar
4223 // mechanisms. This method repairs that damage.
4224
4225 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4226
4227 // Look at each slice.
4228 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4229 Node* old_in = in(i);
4230 // calculate the old memory value
4231 Node* old_mem = old_in;
4232 if (old_mem == empty_mem) old_mem = old_base;
4233 assert(old_mem == memory_at(i), "");
4234
4235 // maybe update (reslice) the old memory value
4236
4237 // simplify stacked MergeMems
4238 Node* new_mem = old_mem;
4239 MergeMemNode* old_mmem;
4240 if (old_mem != NULL && old_mem->is_MergeMem())
4241 old_mmem = old_mem->as_MergeMem();
4242 else
4243 old_mmem = NULL;
4244 if (old_mmem == this) {
4245 // This can happen if loops break up and safepoints disappear.
4246 // A merge of BotPtr (default) with a RawPtr memory derived from a
4247 // safepoint can be rewritten to a merge of the same BotPtr with
4248 // the BotPtr phi coming into the loop. If that phi disappears
4249 // also, we can end up with a self-loop of the mergemem.
4250 // In general, if loops degenerate and memory effects disappear,
4251 // a mergemem can be left looking at itself. This simply means
4252 // that the mergemem's default should be used, since there is
4253 // no longer any apparent effect on this slice.
4254 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4255 // from start. Update the input to TOP.
4256 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4257 }
4258 else if (old_mmem != NULL) {
4259 new_mem = old_mmem->memory_at(i);
4260 }
4261 // else preceding memory was not a MergeMem
4262
4263 // replace equivalent phis (unfortunately, they do not GVN together)
4264 if (new_mem != NULL && new_mem != new_base &&
4265 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4266 if (new_mem->is_Phi()) {
4267 PhiNode* phi_mem = new_mem->as_Phi();
4268 for (uint i = 1; i < phi_len; i++) {
4269 if (phi_base->in(i) != phi_mem->in(i)) {
4270 phi_mem = NULL;
4271 break;
4272 }
4273 }
4274 if (phi_mem != NULL) {
4275 // equivalent phi nodes; revert to the def
4276 new_mem = new_base;
4277 }
4278 }
4279 }
4280
4281 // maybe store down a new value
4282 Node* new_in = new_mem;
4283 if (new_in == new_base) new_in = empty_mem;
4284
4285 if (new_in != old_in) {
4286 // Warning: Do not combine this "if" with the previous "if"
4287 // A memory slice might have be be rewritten even if it is semantically
4288 // unchanged, if the base_memory value has changed.
4289 set_req(i, new_in);
4290 progress = this; // Report progress
4291 }
4292 }
4293
4294 if (new_base != old_base) {
4295 set_req(Compile::AliasIdxBot, new_base);
4296 // Don't use set_base_memory(new_base), because we need to update du.
4297 assert(base_memory() == new_base, "");
4298 progress = this;
4299 }
4300
4301 if( base_memory() == this ) {
4302 // a self cycle indicates this memory path is dead
4303 set_req(Compile::AliasIdxBot, empty_mem);
4304 }
4305
4306 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4307 // Recursion must occur after the self cycle check above
4308 if( base_memory()->is_MergeMem() ) {
4309 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4310 Node *m = phase->transform(new_mbase); // Rollup any cycles
4311 if( m != NULL &&
4312 (m->is_top() ||
4313 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4314 // propagate rollup of dead cycle to self
4315 set_req(Compile::AliasIdxBot, empty_mem);
4316 }
4317 }
4318
4319 if( base_memory() == empty_mem ) {
4320 progress = this;
4321 // Cut inputs during Parse phase only.
4322 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4323 if( !can_reshape ) {
4324 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4325 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4326 }
4327 }
4328 }
4329
4330 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4331 // Check if PhiNode::Ideal's "Split phis through memory merges"
4332 // transform should be attempted. Look for this->phi->this cycle.
4333 uint merge_width = req();
4334 if (merge_width > Compile::AliasIdxRaw) {
4335 PhiNode* phi = base_memory()->as_Phi();
4336 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4337 if (phi->in(i) == this) {
4338 phase->is_IterGVN()->_worklist.push(phi);
4339 break;
4340 }
4341 }
4342 }
4343 }
4344
4345 assert(progress || verify_sparse(), "please, no dups of base");
4346 return progress;
4347 }
4348
4349 //-------------------------set_base_memory-------------------------------------
4350 void MergeMemNode::set_base_memory(Node *new_base) {
4351 Node* empty_mem = empty_memory();
4352 set_req(Compile::AliasIdxBot, new_base);
4353 assert(memory_at(req()) == new_base, "must set default memory");
4354 // Clear out other occurrences of new_base:
4355 if (new_base != empty_mem) {
4356 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4357 if (in(i) == new_base) set_req(i, empty_mem);
4358 }
4359 }
4360 }
4361
4362 //------------------------------out_RegMask------------------------------------
4363 const RegMask &MergeMemNode::out_RegMask() const {
4364 return RegMask::Empty;
4365 }
4366
4367 //------------------------------dump_spec--------------------------------------
4368 #ifndef PRODUCT
4369 void MergeMemNode::dump_spec(outputStream *st) const {
4370 st->print(" {");
4371 Node* base_mem = base_memory();
4372 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4373 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4374 if (mem == base_mem) { st->print(" -"); continue; }
4375 st->print( " N%d:", mem->_idx );
4376 Compile::current()->get_adr_type(i)->dump_on(st);
4377 }
4378 st->print(" }");
4379 }
4380 #endif // !PRODUCT
4381
4382
4383 #ifdef ASSERT
4384 static bool might_be_same(Node* a, Node* b) {
4385 if (a == b) return true;
4386 if (!(a->is_Phi() || b->is_Phi())) return false;
4387 // phis shift around during optimization
4388 return true; // pretty stupid...
4389 }
4390
4391 // verify a narrow slice (either incoming or outgoing)
4392 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4393 if (!VerifyAliases) return; // don't bother to verify unless requested
4394 if (is_error_reported()) return; // muzzle asserts when debugging an error
4395 if (Node::in_dump()) return; // muzzle asserts when printing
4396 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4397 assert(n != NULL, "");
4398 // Elide intervening MergeMem's
4399 while (n->is_MergeMem()) {
4400 n = n->as_MergeMem()->memory_at(alias_idx);
4401 }
4402 Compile* C = Compile::current();
4403 const TypePtr* n_adr_type = n->adr_type();
4404 if (n == m->empty_memory()) {
4405 // Implicit copy of base_memory()
4406 } else if (n_adr_type != TypePtr::BOTTOM) {
4407 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4408 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4409 } else {
4410 // A few places like make_runtime_call "know" that VM calls are narrow,
4411 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4412 bool expected_wide_mem = false;
4413 if (n == m->base_memory()) {
4414 expected_wide_mem = true;
4415 } else if (alias_idx == Compile::AliasIdxRaw ||
4416 n == m->memory_at(Compile::AliasIdxRaw)) {
4417 expected_wide_mem = true;
4418 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4419 // memory can "leak through" calls on channels that
4420 // are write-once. Allow this also.
4421 expected_wide_mem = true;
4422 }
4423 assert(expected_wide_mem, "expected narrow slice replacement");
4424 }
4425 }
4426 #else // !ASSERT
4427 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4428 #endif
4429
4430
4431 //-----------------------------memory_at---------------------------------------
4432 Node* MergeMemNode::memory_at(uint alias_idx) const {
4433 assert(alias_idx >= Compile::AliasIdxRaw ||
4434 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4435 "must avoid base_memory and AliasIdxTop");
4436
4437 // Otherwise, it is a narrow slice.
4438 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4439 Compile *C = Compile::current();
4440 if (is_empty_memory(n)) {
4441 // the array is sparse; empty slots are the "top" node
4442 n = base_memory();
4443 assert(Node::in_dump()
4444 || n == NULL || n->bottom_type() == Type::TOP
4445 || n->adr_type() == NULL // address is TOP
4446 || n->adr_type() == TypePtr::BOTTOM
4447 || n->adr_type() == TypeRawPtr::BOTTOM
4448 || Compile::current()->AliasLevel() == 0,
4449 "must be a wide memory");
4450 // AliasLevel == 0 if we are organizing the memory states manually.
4451 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4452 } else {
4453 // make sure the stored slice is sane
4454 #ifdef ASSERT
4455 if (is_error_reported() || Node::in_dump()) {
4456 } else if (might_be_same(n, base_memory())) {
4457 // Give it a pass: It is a mostly harmless repetition of the base.
4458 // This can arise normally from node subsumption during optimization.
4459 } else {
4460 verify_memory_slice(this, alias_idx, n);
4461 }
4462 #endif
4463 }
4464 return n;
4465 }
4466
4467 //---------------------------set_memory_at-------------------------------------
4468 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4469 verify_memory_slice(this, alias_idx, n);
4470 Node* empty_mem = empty_memory();
4471 if (n == base_memory()) n = empty_mem; // collapse default
4472 uint need_req = alias_idx+1;
4473 if (req() < need_req) {
4474 if (n == empty_mem) return; // already the default, so do not grow me
4475 // grow the sparse array
4476 do {
4477 add_req(empty_mem);
4478 } while (req() < need_req);
4479 }
4480 set_req( alias_idx, n );
4481 }
4482
4483
4484
4485 //--------------------------iteration_setup------------------------------------
4486 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4487 if (other != NULL) {
4488 grow_to_match(other);
4489 // invariant: the finite support of mm2 is within mm->req()
4490 #ifdef ASSERT
4491 for (uint i = req(); i < other->req(); i++) {
4492 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4493 }
4494 #endif
4495 }
4496 // Replace spurious copies of base_memory by top.
4497 Node* base_mem = base_memory();
4498 if (base_mem != NULL && !base_mem->is_top()) {
4499 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4500 if (in(i) == base_mem)
4501 set_req(i, empty_memory());
4502 }
4503 }
4504 }
4505
4506 //---------------------------grow_to_match-------------------------------------
4507 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4508 Node* empty_mem = empty_memory();
4509 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4510 // look for the finite support of the other memory
4511 for (uint i = other->req(); --i >= req(); ) {
4512 if (other->in(i) != empty_mem) {
4513 uint new_len = i+1;
4514 while (req() < new_len) add_req(empty_mem);
4515 break;
4516 }
4517 }
4518 }
4519
4520 //---------------------------verify_sparse-------------------------------------
4521 #ifndef PRODUCT
4522 bool MergeMemNode::verify_sparse() const {
4523 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4524 Node* base_mem = base_memory();
4525 // The following can happen in degenerate cases, since empty==top.
4526 if (is_empty_memory(base_mem)) return true;
4527 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4528 assert(in(i) != NULL, "sane slice");
4529 if (in(i) == base_mem) return false; // should have been the sentinel value!
4530 }
4531 return true;
4532 }
4533
4534 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4535 Node* n;
4536 n = mm->in(idx);
4537 if (mem == n) return true; // might be empty_memory()
4538 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4539 if (mem == n) return true;
4540 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4541 if (mem == n) return true;
4542 if (n == NULL) break;
4543 }
4544 return false;
4545 }
4546 #endif // !PRODUCT