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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "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/align.hpp"
46 #include "utilities/copy.hpp"
47 #include "utilities/vmError.hpp"
48
49 // Portions of code courtesy of Clifford Click
50
51 // Optimization - Graph Style
52
53 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
54
55 //=============================================================================
56 uint MemNode::size_of() const { return sizeof(*this); }
57
58 const TypePtr *MemNode::adr_type() const {
59 Node* adr = in(Address);
60 if (adr == NULL) return NULL; // node is dead
61 const TypePtr* cross_check = NULL;
62 DEBUG_ONLY(cross_check = _adr_type);
63 return calculate_adr_type(adr->bottom_type(), cross_check);
64 }
65
66 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
67 if (adr != NULL) {
68 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
69 return true;
70 }
71 }
72 return false;
73 }
74
75 #ifndef PRODUCT
76 void MemNode::dump_spec(outputStream *st) const {
77 if (in(Address) == NULL) return; // node is dead
78 #ifndef ASSERT
79 // fake the missing field
80 const TypePtr* _adr_type = NULL;
81 if (in(Address) != NULL)
82 _adr_type = in(Address)->bottom_type()->isa_ptr();
83 #endif
84 dump_adr_type(this, _adr_type, st);
85
86 Compile* C = Compile::current();
87 if (C->alias_type(_adr_type)->is_volatile()) {
88 st->print(" Volatile!");
89 }
90 if (_unaligned_access) {
91 st->print(" unaligned");
92 }
93 if (_mismatched_access) {
94 st->print(" mismatched");
95 }
96 }
97
98 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
99 st->print(" @");
100 if (adr_type == NULL) {
101 st->print("NULL");
102 } else {
103 adr_type->dump_on(st);
104 Compile* C = Compile::current();
105 Compile::AliasType* atp = NULL;
106 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
107 if (atp == NULL)
108 st->print(", idx=?\?;");
109 else if (atp->index() == Compile::AliasIdxBot)
110 st->print(", idx=Bot;");
111 else if (atp->index() == Compile::AliasIdxTop)
112 st->print(", idx=Top;");
113 else if (atp->index() == Compile::AliasIdxRaw)
114 st->print(", idx=Raw;");
115 else {
116 ciField* field = atp->field();
117 if (field) {
118 st->print(", name=");
119 field->print_name_on(st);
120 }
121 st->print(", idx=%d;", atp->index());
122 }
123 }
124 }
125
126 extern void print_alias_types();
127
128 #endif
129
130 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
131 assert((t_oop != NULL), "sanity");
132 bool is_instance = t_oop->is_known_instance_field();
133 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
134 (load != NULL) && load->is_Load() &&
135 (phase->is_IterGVN() != NULL);
136 if (!(is_instance || is_boxed_value_load))
137 return mchain; // don't try to optimize non-instance types
138 uint instance_id = t_oop->instance_id();
139 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
140 Node *prev = NULL;
141 Node *result = mchain;
142 while (prev != result) {
143 prev = result;
144 if (result == start_mem)
145 break; // hit one of our sentinels
146 // skip over a call which does not affect this memory slice
147 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
148 Node *proj_in = result->in(0);
149 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
150 break; // hit one of our sentinels
151 } else if (proj_in->is_Call()) {
152 // ArrayCopyNodes processed here as well
153 CallNode *call = proj_in->as_Call();
154 if (!call->may_modify(t_oop, phase)) { // returns false for instances
155 result = call->in(TypeFunc::Memory);
156 }
157 } else if (proj_in->is_Initialize()) {
158 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
159 // Stop if this is the initialization for the object instance which
160 // contains this memory slice, otherwise skip over it.
161 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
162 break;
163 }
164 if (is_instance) {
165 result = proj_in->in(TypeFunc::Memory);
166 } else if (is_boxed_value_load) {
167 Node* klass = alloc->in(AllocateNode::KlassNode);
168 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
169 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
170 result = proj_in->in(TypeFunc::Memory); // not related allocation
171 }
172 }
173 } else if (proj_in->is_MemBar()) {
174 ArrayCopyNode* ac = NULL;
175 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
176 break;
177 }
178 result = proj_in->in(TypeFunc::Memory);
179 } else {
180 assert(false, "unexpected projection");
181 }
182 } else if (result->is_ClearArray()) {
183 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
184 // Can not bypass initialization of the instance
185 // we are looking for.
186 break;
187 }
188 // Otherwise skip it (the call updated 'result' value).
189 } else if (result->is_MergeMem()) {
190 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
191 }
192 }
193 return result;
194 }
195
196 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
197 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
198 if (t_oop == NULL)
199 return mchain; // don't try to optimize non-oop types
200 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
201 bool is_instance = t_oop->is_known_instance_field();
202 PhaseIterGVN *igvn = phase->is_IterGVN();
203 if (is_instance && igvn != NULL && result->is_Phi()) {
204 PhiNode *mphi = result->as_Phi();
205 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
206 const TypePtr *t = mphi->adr_type();
207 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
208 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
209 t->is_oopptr()->cast_to_exactness(true)
210 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
211 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
212 // clone the Phi with our address type
213 result = mphi->split_out_instance(t_adr, igvn);
214 } else {
215 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
216 }
217 }
218 return result;
219 }
220
221 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
222 uint alias_idx = phase->C->get_alias_index(tp);
223 Node *mem = mmem;
224 #ifdef ASSERT
225 {
226 // Check that current type is consistent with the alias index used during graph construction
227 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
228 bool consistent = adr_check == NULL || adr_check->empty() ||
229 phase->C->must_alias(adr_check, alias_idx );
230 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
231 if( !consistent && adr_check != NULL && !adr_check->empty() &&
232 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
233 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
234 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
235 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
236 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
237 // don't assert if it is dead code.
238 consistent = true;
239 }
240 if( !consistent ) {
241 st->print("alias_idx==%d, adr_check==", alias_idx);
242 if( adr_check == NULL ) {
243 st->print("NULL");
244 } else {
245 adr_check->dump();
246 }
247 st->cr();
248 print_alias_types();
249 assert(consistent, "adr_check must match alias idx");
250 }
251 }
252 #endif
253 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
254 // means an array I have not precisely typed yet. Do not do any
255 // alias stuff with it any time soon.
256 const TypeOopPtr *toop = tp->isa_oopptr();
257 if( tp->base() != Type::AnyPtr &&
258 !(toop &&
259 toop->klass() != NULL &&
260 toop->klass()->is_java_lang_Object() &&
261 toop->offset() == Type::OffsetBot) ) {
262 // compress paths and change unreachable cycles to TOP
263 // If not, we can update the input infinitely along a MergeMem cycle
264 // Equivalent code in PhiNode::Ideal
265 Node* m = phase->transform(mmem);
266 // If transformed to a MergeMem, get the desired slice
267 // Otherwise the returned node represents memory for every slice
268 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
269 // Update input if it is progress over what we have now
270 }
271 return mem;
272 }
273
274 //--------------------------Ideal_common---------------------------------------
275 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
276 // Unhook non-raw memories from complete (macro-expanded) initializations.
277 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
278 // If our control input is a dead region, kill all below the region
279 Node *ctl = in(MemNode::Control);
280 if (ctl && remove_dead_region(phase, can_reshape))
281 return this;
282 ctl = in(MemNode::Control);
283 // Don't bother trying to transform a dead node
284 if (ctl && ctl->is_top()) return NodeSentinel;
285
286 PhaseIterGVN *igvn = phase->is_IterGVN();
287 // Wait if control on the worklist.
288 if (ctl && can_reshape && igvn != NULL) {
289 Node* bol = NULL;
290 Node* cmp = NULL;
291 if (ctl->in(0)->is_If()) {
292 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
293 bol = ctl->in(0)->in(1);
294 if (bol->is_Bool())
295 cmp = ctl->in(0)->in(1)->in(1);
296 }
297 if (igvn->_worklist.member(ctl) ||
298 (bol != NULL && igvn->_worklist.member(bol)) ||
299 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
300 // This control path may be dead.
301 // Delay this memory node transformation until the control is processed.
302 phase->is_IterGVN()->_worklist.push(this);
303 return NodeSentinel; // caller will return NULL
304 }
305 }
306 // Ignore if memory is dead, or self-loop
307 Node *mem = in(MemNode::Memory);
308 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
309 assert(mem != this, "dead loop in MemNode::Ideal");
310
311 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
312 // This memory slice may be dead.
313 // Delay this mem node transformation until the memory is processed.
314 phase->is_IterGVN()->_worklist.push(this);
315 return NodeSentinel; // caller will return NULL
316 }
317
318 Node *address = in(MemNode::Address);
319 const Type *t_adr = phase->type(address);
320 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
321
322 if (can_reshape && igvn != NULL &&
323 (igvn->_worklist.member(address) ||
324 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
325 // The address's base and type may change when the address is processed.
326 // Delay this mem node transformation until the address is processed.
327 phase->is_IterGVN()->_worklist.push(this);
328 return NodeSentinel; // caller will return NULL
329 }
330
331 // Do NOT remove or optimize the next lines: ensure a new alias index
332 // is allocated for an oop pointer type before Escape Analysis.
333 // Note: C++ will not remove it since the call has side effect.
334 if (t_adr->isa_oopptr()) {
335 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
336 }
337
338 Node* base = NULL;
339 if (address->is_AddP()) {
340 base = address->in(AddPNode::Base);
341 }
342 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
343 !t_adr->isa_rawptr()) {
344 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
345 // Skip this node optimization if its address has TOP base.
346 return NodeSentinel; // caller will return NULL
347 }
348
349 // Avoid independent memory operations
350 Node* old_mem = mem;
351
352 // The code which unhooks non-raw memories from complete (macro-expanded)
353 // initializations was removed. After macro-expansion all stores catched
354 // by Initialize node became raw stores and there is no information
355 // which memory slices they modify. So it is unsafe to move any memory
356 // operation above these stores. Also in most cases hooked non-raw memories
357 // were already unhooked by using information from detect_ptr_independence()
358 // and find_previous_store().
359
360 if (mem->is_MergeMem()) {
361 MergeMemNode* mmem = mem->as_MergeMem();
362 const TypePtr *tp = t_adr->is_ptr();
363
364 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
365 }
366
367 if (mem != old_mem) {
368 set_req(MemNode::Memory, mem);
369 if (can_reshape && old_mem->outcnt() == 0) {
370 igvn->_worklist.push(old_mem);
371 }
372 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
373 return this;
374 }
375
376 // let the subclass continue analyzing...
377 return NULL;
378 }
379
380 // Helper function for proving some simple control dominations.
381 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
382 // Already assumes that 'dom' is available at 'sub', and that 'sub'
383 // is not a constant (dominated by the method's StartNode).
384 // Used by MemNode::find_previous_store to prove that the
385 // control input of a memory operation predates (dominates)
386 // an allocation it wants to look past.
387 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
388 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
389 return false; // Conservative answer for dead code
390
391 // Check 'dom'. Skip Proj and CatchProj nodes.
392 dom = dom->find_exact_control(dom);
393 if (dom == NULL || dom->is_top())
394 return false; // Conservative answer for dead code
395
396 if (dom == sub) {
397 // For the case when, for example, 'sub' is Initialize and the original
398 // 'dom' is Proj node of the 'sub'.
399 return false;
400 }
401
402 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
403 return true;
404
405 // 'dom' dominates 'sub' if its control edge and control edges
406 // of all its inputs dominate or equal to sub's control edge.
407
408 // Currently 'sub' is either Allocate, Initialize or Start nodes.
409 // Or Region for the check in LoadNode::Ideal();
410 // 'sub' should have sub->in(0) != NULL.
411 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
412 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
413
414 // Get control edge of 'sub'.
415 Node* orig_sub = sub;
416 sub = sub->find_exact_control(sub->in(0));
417 if (sub == NULL || sub->is_top())
418 return false; // Conservative answer for dead code
419
420 assert(sub->is_CFG(), "expecting control");
421
422 if (sub == dom)
423 return true;
424
425 if (sub->is_Start() || sub->is_Root())
426 return false;
427
428 {
429 // Check all control edges of 'dom'.
430
431 ResourceMark rm;
432 Arena* arena = Thread::current()->resource_area();
433 Node_List nlist(arena);
434 Unique_Node_List dom_list(arena);
435
436 dom_list.push(dom);
437 bool only_dominating_controls = false;
438
439 for (uint next = 0; next < dom_list.size(); next++) {
440 Node* n = dom_list.at(next);
441 if (n == orig_sub)
442 return false; // One of dom's inputs dominated by sub.
443 if (!n->is_CFG() && n->pinned()) {
444 // Check only own control edge for pinned non-control nodes.
445 n = n->find_exact_control(n->in(0));
446 if (n == NULL || n->is_top())
447 return false; // Conservative answer for dead code
448 assert(n->is_CFG(), "expecting control");
449 dom_list.push(n);
450 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
451 only_dominating_controls = true;
452 } else if (n->is_CFG()) {
453 if (n->dominates(sub, nlist))
454 only_dominating_controls = true;
455 else
456 return false;
457 } else {
458 // First, own control edge.
459 Node* m = n->find_exact_control(n->in(0));
460 if (m != NULL) {
461 if (m->is_top())
462 return false; // Conservative answer for dead code
463 dom_list.push(m);
464 }
465 // Now, the rest of edges.
466 uint cnt = n->req();
467 for (uint i = 1; i < cnt; i++) {
468 m = n->find_exact_control(n->in(i));
469 if (m == NULL || m->is_top())
470 continue;
471 dom_list.push(m);
472 }
473 }
474 }
475 return only_dominating_controls;
476 }
477 }
478
479 //---------------------detect_ptr_independence---------------------------------
480 // Used by MemNode::find_previous_store to prove that two base
481 // pointers are never equal.
482 // The pointers are accompanied by their associated allocations,
483 // if any, which have been previously discovered by the caller.
484 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
485 Node* p2, AllocateNode* a2,
486 PhaseTransform* phase) {
487 // Attempt to prove that these two pointers cannot be aliased.
488 // They may both manifestly be allocations, and they should differ.
489 // Or, if they are not both allocations, they can be distinct constants.
490 // Otherwise, one is an allocation and the other a pre-existing value.
491 if (a1 == NULL && a2 == NULL) { // neither an allocation
492 return (p1 != p2) && p1->is_Con() && p2->is_Con();
493 } else if (a1 != NULL && a2 != NULL) { // both allocations
494 return (a1 != a2);
495 } else if (a1 != NULL) { // one allocation a1
496 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
497 return all_controls_dominate(p2, a1);
498 } else { //(a2 != NULL) // one allocation a2
499 return all_controls_dominate(p1, a2);
500 }
501 return false;
502 }
503
504
505 // Find an arraycopy that must have set (can_see_stored_value=true) or
506 // could have set (can_see_stored_value=false) the value for this load
507 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
508 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
509 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
510 Node* mb = mem->in(0);
511 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
512 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
513 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
514 if (ac->is_clonebasic()) {
515 intptr_t offset;
516 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
517 assert(alloc != NULL && (!ReduceBulkZeroing || alloc->initialization()->is_complete_with_arraycopy()), "broken allocation");
518 if (alloc == ld_alloc) {
519 return ac;
520 }
521 }
522 }
523 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
524 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
525
526 if (ac->is_arraycopy_validated() ||
527 ac->is_copyof_validated() ||
528 ac->is_copyofrange_validated()) {
529 Node* ld_addp = in(MemNode::Address);
530 if (ld_addp->is_AddP()) {
531 Node* ld_base = ld_addp->in(AddPNode::Address);
532 Node* ld_offs = ld_addp->in(AddPNode::Offset);
533
534 Node* dest = ac->in(ArrayCopyNode::Dest);
535
536 if (dest == ld_base) {
537 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
538 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
539 return ac;
540 }
541 if (!can_see_stored_value) {
542 mem = ac->in(TypeFunc::Memory);
543 }
544 }
545 }
546 }
547 }
548 return NULL;
549 }
550
551 // The logic for reordering loads and stores uses four steps:
552 // (a) Walk carefully past stores and initializations which we
553 // can prove are independent of this load.
554 // (b) Observe that the next memory state makes an exact match
555 // with self (load or store), and locate the relevant store.
556 // (c) Ensure that, if we were to wire self directly to the store,
557 // the optimizer would fold it up somehow.
558 // (d) Do the rewiring, and return, depending on some other part of
559 // the optimizer to fold up the load.
560 // This routine handles steps (a) and (b). Steps (c) and (d) are
561 // specific to loads and stores, so they are handled by the callers.
562 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
563 //
564 Node* MemNode::find_previous_store(PhaseTransform* phase) {
565 Node* ctrl = in(MemNode::Control);
566 Node* adr = in(MemNode::Address);
567 intptr_t offset = 0;
568 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
569 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
570
571 if (offset == Type::OffsetBot)
572 return NULL; // cannot unalias unless there are precise offsets
573
574 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
575 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
576
577 intptr_t size_in_bytes = memory_size();
578
579 Node* mem = in(MemNode::Memory); // start searching here...
580
581 int cnt = 50; // Cycle limiter
582 for (;;) { // While we can dance past unrelated stores...
583 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
584
585 Node* prev = mem;
586 if (mem->is_Store()) {
587 Node* st_adr = mem->in(MemNode::Address);
588 intptr_t st_offset = 0;
589 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
590 if (st_base == NULL)
591 break; // inscrutable pointer
592
593 // For raw accesses it's not enough to prove that constant offsets don't intersect.
594 // We need the bases to be the equal in order for the offset check to make sense.
595 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
596 break;
597 }
598
599 if (st_offset != offset && st_offset != Type::OffsetBot) {
600 const int MAX_STORE = BytesPerLong;
601 if (st_offset >= offset + size_in_bytes ||
602 st_offset <= offset - MAX_STORE ||
603 st_offset <= offset - mem->as_Store()->memory_size()) {
604 // Success: The offsets are provably independent.
605 // (You may ask, why not just test st_offset != offset and be done?
606 // The answer is that stores of different sizes can co-exist
607 // in the same sequence of RawMem effects. We sometimes initialize
608 // a whole 'tile' of array elements with a single jint or jlong.)
609 mem = mem->in(MemNode::Memory);
610 continue; // (a) advance through independent store memory
611 }
612 }
613 if (st_base != base &&
614 detect_ptr_independence(base, alloc,
615 st_base,
616 AllocateNode::Ideal_allocation(st_base, phase),
617 phase)) {
618 // Success: The bases are provably independent.
619 mem = mem->in(MemNode::Memory);
620 continue; // (a) advance through independent store memory
621 }
622
623 // (b) At this point, if the bases or offsets do not agree, we lose,
624 // since we have not managed to prove 'this' and 'mem' independent.
625 if (st_base == base && st_offset == offset) {
626 return mem; // let caller handle steps (c), (d)
627 }
628
629 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
630 InitializeNode* st_init = mem->in(0)->as_Initialize();
631 AllocateNode* st_alloc = st_init->allocation();
632 if (st_alloc == NULL)
633 break; // something degenerated
634 bool known_identical = false;
635 bool known_independent = false;
636 if (alloc == st_alloc)
637 known_identical = true;
638 else if (alloc != NULL)
639 known_independent = true;
640 else if (all_controls_dominate(this, st_alloc))
641 known_independent = true;
642
643 if (known_independent) {
644 // The bases are provably independent: Either they are
645 // manifestly distinct allocations, or else the control
646 // of this load dominates the store's allocation.
647 int alias_idx = phase->C->get_alias_index(adr_type());
648 if (alias_idx == Compile::AliasIdxRaw) {
649 mem = st_alloc->in(TypeFunc::Memory);
650 } else {
651 mem = st_init->memory(alias_idx);
652 }
653 continue; // (a) advance through independent store memory
654 }
655
656 // (b) at this point, if we are not looking at a store initializing
657 // the same allocation we are loading from, we lose.
658 if (known_identical) {
659 // From caller, can_see_stored_value will consult find_captured_store.
660 return mem; // let caller handle steps (c), (d)
661 }
662
663 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
664 if (prev != mem) {
665 // Found an arraycopy but it doesn't affect that load
666 continue;
667 }
668 // Found an arraycopy that may affect that load
669 return mem;
670 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
671 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
672 if (mem->is_Proj() && mem->in(0)->is_Call()) {
673 // ArrayCopyNodes processed here as well.
674 CallNode *call = mem->in(0)->as_Call();
675 if (!call->may_modify(addr_t, phase)) {
676 mem = call->in(TypeFunc::Memory);
677 continue; // (a) advance through independent call memory
678 }
679 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
680 ArrayCopyNode* ac = NULL;
681 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
682 break;
683 }
684 mem = mem->in(0)->in(TypeFunc::Memory);
685 continue; // (a) advance through independent MemBar memory
686 } else if (mem->is_ClearArray()) {
687 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
688 // (the call updated 'mem' value)
689 continue; // (a) advance through independent allocation memory
690 } else {
691 // Can not bypass initialization of the instance
692 // we are looking for.
693 return mem;
694 }
695 } else if (mem->is_MergeMem()) {
696 int alias_idx = phase->C->get_alias_index(adr_type());
697 mem = mem->as_MergeMem()->memory_at(alias_idx);
698 continue; // (a) advance through independent MergeMem memory
699 }
700 }
701
702 // Unless there is an explicit 'continue', we must bail out here,
703 // because 'mem' is an inscrutable memory state (e.g., a call).
704 break;
705 }
706
707 return NULL; // bail out
708 }
709
710 //----------------------calculate_adr_type-------------------------------------
711 // Helper function. Notices when the given type of address hits top or bottom.
712 // Also, asserts a cross-check of the type against the expected address type.
713 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
714 if (t == Type::TOP) return NULL; // does not touch memory any more?
715 #ifdef PRODUCT
716 cross_check = NULL;
717 #else
718 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
719 #endif
720 const TypePtr* tp = t->isa_ptr();
721 if (tp == NULL) {
722 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
723 return TypePtr::BOTTOM; // touches lots of memory
724 } else {
725 #ifdef ASSERT
726 // %%%% [phh] We don't check the alias index if cross_check is
727 // TypeRawPtr::BOTTOM. Needs to be investigated.
728 if (cross_check != NULL &&
729 cross_check != TypePtr::BOTTOM &&
730 cross_check != TypeRawPtr::BOTTOM) {
731 // Recheck the alias index, to see if it has changed (due to a bug).
732 Compile* C = Compile::current();
733 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
734 "must stay in the original alias category");
735 // The type of the address must be contained in the adr_type,
736 // disregarding "null"-ness.
737 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
738 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
739 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
740 "real address must not escape from expected memory type");
741 }
742 #endif
743 return tp;
744 }
745 }
746
747 //=============================================================================
748 // Should LoadNode::Ideal() attempt to remove control edges?
749 bool LoadNode::can_remove_control() const {
750 return true;
751 }
752 uint LoadNode::size_of() const { return sizeof(*this); }
753 uint LoadNode::cmp( const Node &n ) const
754 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
755 const Type *LoadNode::bottom_type() const { return _type; }
756 uint LoadNode::ideal_reg() const {
757 return _type->ideal_reg();
758 }
759
760 #ifndef PRODUCT
761 void LoadNode::dump_spec(outputStream *st) const {
762 MemNode::dump_spec(st);
763 if( !Verbose && !WizardMode ) {
764 // standard dump does this in Verbose and WizardMode
765 st->print(" #"); _type->dump_on(st);
766 }
767 if (!depends_only_on_test()) {
768 st->print(" (does not depend only on test)");
769 }
770 }
771 #endif
772
773 #ifdef ASSERT
774 //----------------------------is_immutable_value-------------------------------
775 // Helper function to allow a raw load without control edge for some cases
776 bool LoadNode::is_immutable_value(Node* adr) {
777 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
778 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
779 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
780 in_bytes(JavaThread::osthread_offset())));
781 }
782 #endif
783
784 //----------------------------LoadNode::make-----------------------------------
785 // Polymorphic factory method:
786 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
787 ControlDependency control_dependency, bool unaligned, bool mismatched) {
788 Compile* C = gvn.C;
789
790 // sanity check the alias category against the created node type
791 assert(!(adr_type->isa_oopptr() &&
792 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
793 "use LoadKlassNode instead");
794 assert(!(adr_type->isa_aryptr() &&
795 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
796 "use LoadRangeNode instead");
797 // Check control edge of raw loads
798 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
799 // oop will be recorded in oop map if load crosses safepoint
800 rt->isa_oopptr() || is_immutable_value(adr),
801 "raw memory operations should have control edge");
802 LoadNode* load = NULL;
803 switch (bt) {
804 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
805 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
806 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
807 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
808 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
809 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
810 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
811 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
812 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
813 case T_OBJECT:
814 #ifdef _LP64
815 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
816 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
817 } else
818 #endif
819 {
820 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
821 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
822 }
823 break;
824 default:
825 // ShouldNotReachHere(); ???
826 break;
827 }
828 assert(load != NULL, "LoadNode should have been created");
829 if (unaligned) {
830 load->set_unaligned_access();
831 }
832 if (mismatched) {
833 load->set_mismatched_access();
834 }
835 if (load->Opcode() == Op_LoadN) {
836 Node* ld = gvn.transform(load);
837 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
838 }
839
840 return load;
841 }
842
843 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
844 ControlDependency control_dependency, bool unaligned, bool mismatched) {
845 bool require_atomic = true;
846 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
847 if (unaligned) {
848 load->set_unaligned_access();
849 }
850 if (mismatched) {
851 load->set_mismatched_access();
852 }
853 return load;
854 }
855
856 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
857 ControlDependency control_dependency, bool unaligned, bool mismatched) {
858 bool require_atomic = true;
859 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
860 if (unaligned) {
861 load->set_unaligned_access();
862 }
863 if (mismatched) {
864 load->set_mismatched_access();
865 }
866 return load;
867 }
868
869
870
871 //------------------------------hash-------------------------------------------
872 uint LoadNode::hash() const {
873 // unroll addition of interesting fields
874 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
875 }
876
877 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
878 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
879 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
880 bool is_stable_ary = FoldStableValues &&
881 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
882 tp->isa_aryptr()->is_stable();
883
884 return (eliminate_boxing && non_volatile) || is_stable_ary;
885 }
886
887 return false;
888 }
889
890 // Is the value loaded previously stored by an arraycopy? If so return
891 // a load node that reads from the source array so we may be able to
892 // optimize out the ArrayCopy node later.
893 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
894 Node* ld_adr = in(MemNode::Address);
895 intptr_t ld_off = 0;
896 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
897 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
898 if (ac != NULL) {
899 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
900
901 Node* mem = ac->in(TypeFunc::Memory);
902 Node* ctl = ac->in(0);
903 Node* src = ac->in(ArrayCopyNode::Src);
904
905 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
906 return NULL;
907 }
908
909 LoadNode* ld = clone()->as_Load();
910 Node* addp = in(MemNode::Address)->clone();
911 if (ac->as_ArrayCopy()->is_clonebasic()) {
912 assert(ld_alloc != NULL, "need an alloc");
913 assert(addp->is_AddP(), "address must be addp");
914 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
915 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
916 addp->set_req(AddPNode::Base, src->in(AddPNode::Base));
917 addp->set_req(AddPNode::Address, src->in(AddPNode::Address));
918 } else {
919 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
920 ac->as_ArrayCopy()->is_copyof_validated() ||
921 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
922 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
923 addp->set_req(AddPNode::Base, src);
924 addp->set_req(AddPNode::Address, src);
925
926 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
927 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
928 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
929 uint shift = exact_log2(type2aelembytes(ary_elem));
930
931 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
932 #ifdef _LP64
933 diff = phase->transform(new ConvI2LNode(diff));
934 #endif
935 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
936
937 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
938 addp->set_req(AddPNode::Offset, offset);
939 }
940 addp = phase->transform(addp);
941 #ifdef ASSERT
942 const TypePtr* adr_type = phase->type(addp)->is_ptr();
943 ld->_adr_type = adr_type;
944 #endif
945 ld->set_req(MemNode::Address, addp);
946 ld->set_req(0, ctl);
947 ld->set_req(MemNode::Memory, mem);
948 // load depends on the tests that validate the arraycopy
949 ld->_control_dependency = Pinned;
950 return ld;
951 }
952 return NULL;
953 }
954
955
956 //---------------------------can_see_stored_value------------------------------
957 // This routine exists to make sure this set of tests is done the same
958 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
959 // will change the graph shape in a way which makes memory alive twice at the
960 // same time (uses the Oracle model of aliasing), then some
961 // LoadXNode::Identity will fold things back to the equivalence-class model
962 // of aliasing.
963 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
964 Node* ld_adr = in(MemNode::Address);
965 intptr_t ld_off = 0;
966 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
967 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
968 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
969 // This is more general than load from boxing objects.
970 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
971 uint alias_idx = atp->index();
972 bool final = !atp->is_rewritable();
973 Node* result = NULL;
974 Node* current = st;
975 // Skip through chains of MemBarNodes checking the MergeMems for
976 // new states for the slice of this load. Stop once any other
977 // kind of node is encountered. Loads from final memory can skip
978 // through any kind of MemBar but normal loads shouldn't skip
979 // through MemBarAcquire since the could allow them to move out of
980 // a synchronized region.
981 while (current->is_Proj()) {
982 int opc = current->in(0)->Opcode();
983 if ((final && (opc == Op_MemBarAcquire ||
984 opc == Op_MemBarAcquireLock ||
985 opc == Op_LoadFence)) ||
986 opc == Op_MemBarRelease ||
987 opc == Op_StoreFence ||
988 opc == Op_MemBarReleaseLock ||
989 opc == Op_MemBarStoreStore ||
990 opc == Op_MemBarCPUOrder) {
991 Node* mem = current->in(0)->in(TypeFunc::Memory);
992 if (mem->is_MergeMem()) {
993 MergeMemNode* merge = mem->as_MergeMem();
994 Node* new_st = merge->memory_at(alias_idx);
995 if (new_st == merge->base_memory()) {
996 // Keep searching
997 current = new_st;
998 continue;
999 }
1000 // Save the new memory state for the slice and fall through
1001 // to exit.
1002 result = new_st;
1003 }
1004 }
1005 break;
1006 }
1007 if (result != NULL) {
1008 st = result;
1009 }
1010 }
1011
1012 // Loop around twice in the case Load -> Initialize -> Store.
1013 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1014 for (int trip = 0; trip <= 1; trip++) {
1015
1016 if (st->is_Store()) {
1017 Node* st_adr = st->in(MemNode::Address);
1018 if (!phase->eqv(st_adr, ld_adr)) {
1019 // Try harder before giving up... Match raw and non-raw pointers.
1020 intptr_t st_off = 0;
1021 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
1022 if (alloc == NULL) return NULL;
1023 if (alloc != ld_alloc) return NULL;
1024 if (ld_off != st_off) return NULL;
1025 // At this point we have proven something like this setup:
1026 // A = Allocate(...)
1027 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
1028 // S = StoreQ(, AddP(, A.Parm , #Off), V)
1029 // (Actually, we haven't yet proven the Q's are the same.)
1030 // In other words, we are loading from a casted version of
1031 // the same pointer-and-offset that we stored to.
1032 // Thus, we are able to replace L by V.
1033 }
1034 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1035 if (store_Opcode() != st->Opcode())
1036 return NULL;
1037 return st->in(MemNode::ValueIn);
1038 }
1039
1040 // A load from a freshly-created object always returns zero.
1041 // (This can happen after LoadNode::Ideal resets the load's memory input
1042 // to find_captured_store, which returned InitializeNode::zero_memory.)
1043 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1044 (st->in(0) == ld_alloc) &&
1045 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1046 // return a zero value for the load's basic type
1047 // (This is one of the few places where a generic PhaseTransform
1048 // can create new nodes. Think of it as lazily manifesting
1049 // virtually pre-existing constants.)
1050 return phase->zerocon(memory_type());
1051 }
1052
1053 // A load from an initialization barrier can match a captured store.
1054 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1055 InitializeNode* init = st->in(0)->as_Initialize();
1056 AllocateNode* alloc = init->allocation();
1057 if ((alloc != NULL) && (alloc == ld_alloc)) {
1058 // examine a captured store value
1059 st = init->find_captured_store(ld_off, memory_size(), phase);
1060 if (st != NULL) {
1061 continue; // take one more trip around
1062 }
1063 }
1064 }
1065
1066 // Load boxed value from result of valueOf() call is input parameter.
1067 if (this->is_Load() && ld_adr->is_AddP() &&
1068 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1069 intptr_t ignore = 0;
1070 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1071 if (base != NULL && base->is_Proj() &&
1072 base->as_Proj()->_con == TypeFunc::Parms &&
1073 base->in(0)->is_CallStaticJava() &&
1074 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1075 return base->in(0)->in(TypeFunc::Parms);
1076 }
1077 }
1078
1079 break;
1080 }
1081
1082 return NULL;
1083 }
1084
1085 //----------------------is_instance_field_load_with_local_phi------------------
1086 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1087 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1088 in(Address)->is_AddP() ) {
1089 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1090 // Only instances and boxed values.
1091 if( t_oop != NULL &&
1092 (t_oop->is_ptr_to_boxed_value() ||
1093 t_oop->is_known_instance_field()) &&
1094 t_oop->offset() != Type::OffsetBot &&
1095 t_oop->offset() != Type::OffsetTop) {
1096 return true;
1097 }
1098 }
1099 return false;
1100 }
1101
1102 //------------------------------Identity---------------------------------------
1103 // Loads are identity if previous store is to same address
1104 Node* LoadNode::Identity(PhaseGVN* phase) {
1105 // If the previous store-maker is the right kind of Store, and the store is
1106 // to the same address, then we are equal to the value stored.
1107 Node* mem = in(Memory);
1108 Node* value = can_see_stored_value(mem, phase);
1109 if( value ) {
1110 // byte, short & char stores truncate naturally.
1111 // A load has to load the truncated value which requires
1112 // some sort of masking operation and that requires an
1113 // Ideal call instead of an Identity call.
1114 if (memory_size() < BytesPerInt) {
1115 // If the input to the store does not fit with the load's result type,
1116 // it must be truncated via an Ideal call.
1117 if (!phase->type(value)->higher_equal(phase->type(this)))
1118 return this;
1119 }
1120 // (This works even when value is a Con, but LoadNode::Value
1121 // usually runs first, producing the singleton type of the Con.)
1122 return value;
1123 }
1124
1125 // Search for an existing data phi which was generated before for the same
1126 // instance's field to avoid infinite generation of phis in a loop.
1127 Node *region = mem->in(0);
1128 if (is_instance_field_load_with_local_phi(region)) {
1129 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1130 int this_index = phase->C->get_alias_index(addr_t);
1131 int this_offset = addr_t->offset();
1132 int this_iid = addr_t->instance_id();
1133 if (!addr_t->is_known_instance() &&
1134 addr_t->is_ptr_to_boxed_value()) {
1135 // Use _idx of address base (could be Phi node) for boxed values.
1136 intptr_t ignore = 0;
1137 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1138 if (base == NULL) {
1139 return this;
1140 }
1141 this_iid = base->_idx;
1142 }
1143 const Type* this_type = bottom_type();
1144 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1145 Node* phi = region->fast_out(i);
1146 if (phi->is_Phi() && phi != mem &&
1147 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1148 return phi;
1149 }
1150 }
1151 }
1152
1153 return this;
1154 }
1155
1156 // Construct an equivalent unsigned load.
1157 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1158 BasicType bt = T_ILLEGAL;
1159 const Type* rt = NULL;
1160 switch (Opcode()) {
1161 case Op_LoadUB: return this;
1162 case Op_LoadUS: return this;
1163 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1164 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1165 default:
1166 assert(false, "no unsigned variant: %s", Name());
1167 return NULL;
1168 }
1169 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1170 raw_adr_type(), rt, bt, _mo, _control_dependency,
1171 is_unaligned_access(), is_mismatched_access());
1172 }
1173
1174 // Construct an equivalent signed load.
1175 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1176 BasicType bt = T_ILLEGAL;
1177 const Type* rt = NULL;
1178 switch (Opcode()) {
1179 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1180 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1181 case Op_LoadB: // fall through
1182 case Op_LoadS: // fall through
1183 case Op_LoadI: // fall through
1184 case Op_LoadL: return this;
1185 default:
1186 assert(false, "no signed variant: %s", Name());
1187 return NULL;
1188 }
1189 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1190 raw_adr_type(), rt, bt, _mo, _control_dependency,
1191 is_unaligned_access(), is_mismatched_access());
1192 }
1193
1194 // We're loading from an object which has autobox behaviour.
1195 // If this object is result of a valueOf call we'll have a phi
1196 // merging a newly allocated object and a load from the cache.
1197 // We want to replace this load with the original incoming
1198 // argument to the valueOf call.
1199 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1200 assert(phase->C->eliminate_boxing(), "sanity");
1201 intptr_t ignore = 0;
1202 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1203 if ((base == NULL) || base->is_Phi()) {
1204 // Push the loads from the phi that comes from valueOf up
1205 // through it to allow elimination of the loads and the recovery
1206 // of the original value. It is done in split_through_phi().
1207 return NULL;
1208 } else if (base->is_Load() ||
1209 (base->is_DecodeN() && base->in(1)->is_Load())) {
1210 // Eliminate the load of boxed value for integer types from the cache
1211 // array by deriving the value from the index into the array.
1212 // Capture the offset of the load and then reverse the computation.
1213
1214 // Get LoadN node which loads a boxing object from 'cache' array.
1215 if (base->is_DecodeN()) {
1216 base = base->in(1);
1217 }
1218 if (!base->in(Address)->is_AddP()) {
1219 return NULL; // Complex address
1220 }
1221 AddPNode* address = base->in(Address)->as_AddP();
1222 Node* cache_base = address->in(AddPNode::Base);
1223 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1224 // Get ConP node which is static 'cache' field.
1225 cache_base = cache_base->in(1);
1226 }
1227 if ((cache_base != NULL) && cache_base->is_Con()) {
1228 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1229 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1230 Node* elements[4];
1231 int shift = exact_log2(type2aelembytes(T_OBJECT));
1232 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1233 if (count > 0 && elements[0]->is_Con() &&
1234 (count == 1 ||
1235 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1236 elements[1]->in(2) == phase->intcon(shift)))) {
1237 ciObjArray* array = base_type->const_oop()->as_obj_array();
1238 // Fetch the box object cache[0] at the base of the array and get its value
1239 ciInstance* box = array->obj_at(0)->as_instance();
1240 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1241 assert(ik->is_box_klass(), "sanity");
1242 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1243 if (ik->nof_nonstatic_fields() == 1) {
1244 // This should be true nonstatic_field_at requires calling
1245 // nof_nonstatic_fields so check it anyway
1246 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1247 BasicType bt = c.basic_type();
1248 // Only integer types have boxing cache.
1249 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1250 bt == T_BYTE || bt == T_SHORT ||
1251 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1252 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1253 if (cache_low != (int)cache_low) {
1254 return NULL; // should not happen since cache is array indexed by value
1255 }
1256 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1257 if (offset != (int)offset) {
1258 return NULL; // should not happen since cache is array indexed by value
1259 }
1260 // Add up all the offsets making of the address of the load
1261 Node* result = elements[0];
1262 for (int i = 1; i < count; i++) {
1263 result = phase->transform(new AddXNode(result, elements[i]));
1264 }
1265 // Remove the constant offset from the address and then
1266 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1267 // remove the scaling of the offset to recover the original index.
1268 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1269 // Peel the shift off directly but wrap it in a dummy node
1270 // since Ideal can't return existing nodes
1271 result = new RShiftXNode(result->in(1), phase->intcon(0));
1272 } else if (result->is_Add() && result->in(2)->is_Con() &&
1273 result->in(1)->Opcode() == Op_LShiftX &&
1274 result->in(1)->in(2) == phase->intcon(shift)) {
1275 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1276 // but for boxing cache access we know that X<<Z will not overflow
1277 // (there is range check) so we do this optimizatrion by hand here.
1278 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1279 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1280 } else {
1281 result = new RShiftXNode(result, phase->intcon(shift));
1282 }
1283 #ifdef _LP64
1284 if (bt != T_LONG) {
1285 result = new ConvL2INode(phase->transform(result));
1286 }
1287 #else
1288 if (bt == T_LONG) {
1289 result = new ConvI2LNode(phase->transform(result));
1290 }
1291 #endif
1292 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1293 // Need to preserve unboxing load type if it is unsigned.
1294 switch(this->Opcode()) {
1295 case Op_LoadUB:
1296 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1297 break;
1298 case Op_LoadUS:
1299 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1300 break;
1301 }
1302 return result;
1303 }
1304 }
1305 }
1306 }
1307 }
1308 return NULL;
1309 }
1310
1311 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1312 Node* region = phi->in(0);
1313 if (region == NULL) {
1314 return false; // Wait stable graph
1315 }
1316 uint cnt = phi->req();
1317 for (uint i = 1; i < cnt; i++) {
1318 Node* rc = region->in(i);
1319 if (rc == NULL || phase->type(rc) == Type::TOP)
1320 return false; // Wait stable graph
1321 Node* in = phi->in(i);
1322 if (in == NULL || phase->type(in) == Type::TOP)
1323 return false; // Wait stable graph
1324 }
1325 return true;
1326 }
1327 //------------------------------split_through_phi------------------------------
1328 // Split instance or boxed field load through Phi.
1329 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1330 Node* mem = in(Memory);
1331 Node* address = in(Address);
1332 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1333
1334 assert((t_oop != NULL) &&
1335 (t_oop->is_known_instance_field() ||
1336 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1337
1338 Compile* C = phase->C;
1339 intptr_t ignore = 0;
1340 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1341 bool base_is_phi = (base != NULL) && base->is_Phi();
1342 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1343 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1344 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1345
1346 if (!((mem->is_Phi() || base_is_phi) &&
1347 (load_boxed_values || t_oop->is_known_instance_field()))) {
1348 return NULL; // memory is not Phi
1349 }
1350
1351 if (mem->is_Phi()) {
1352 if (!stable_phi(mem->as_Phi(), phase)) {
1353 return NULL; // Wait stable graph
1354 }
1355 uint cnt = mem->req();
1356 // Check for loop invariant memory.
1357 if (cnt == 3) {
1358 for (uint i = 1; i < cnt; i++) {
1359 Node* in = mem->in(i);
1360 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1361 if (m == mem) {
1362 set_req(Memory, mem->in(cnt - i));
1363 return this; // made change
1364 }
1365 }
1366 }
1367 }
1368 if (base_is_phi) {
1369 if (!stable_phi(base->as_Phi(), phase)) {
1370 return NULL; // Wait stable graph
1371 }
1372 uint cnt = base->req();
1373 // Check for loop invariant memory.
1374 if (cnt == 3) {
1375 for (uint i = 1; i < cnt; i++) {
1376 if (base->in(i) == base) {
1377 return NULL; // Wait stable graph
1378 }
1379 }
1380 }
1381 }
1382
1383 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1384
1385 // Split through Phi (see original code in loopopts.cpp).
1386 assert(C->have_alias_type(t_oop), "instance should have alias type");
1387
1388 // Do nothing here if Identity will find a value
1389 // (to avoid infinite chain of value phis generation).
1390 if (!phase->eqv(this, this->Identity(phase)))
1391 return NULL;
1392
1393 // Select Region to split through.
1394 Node* region;
1395 if (!base_is_phi) {
1396 assert(mem->is_Phi(), "sanity");
1397 region = mem->in(0);
1398 // Skip if the region dominates some control edge of the address.
1399 if (!MemNode::all_controls_dominate(address, region))
1400 return NULL;
1401 } else if (!mem->is_Phi()) {
1402 assert(base_is_phi, "sanity");
1403 region = base->in(0);
1404 // Skip if the region dominates some control edge of the memory.
1405 if (!MemNode::all_controls_dominate(mem, region))
1406 return NULL;
1407 } else if (base->in(0) != mem->in(0)) {
1408 assert(base_is_phi && mem->is_Phi(), "sanity");
1409 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1410 region = base->in(0);
1411 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1412 region = mem->in(0);
1413 } else {
1414 return NULL; // complex graph
1415 }
1416 } else {
1417 assert(base->in(0) == mem->in(0), "sanity");
1418 region = mem->in(0);
1419 }
1420
1421 const Type* this_type = this->bottom_type();
1422 int this_index = C->get_alias_index(t_oop);
1423 int this_offset = t_oop->offset();
1424 int this_iid = t_oop->instance_id();
1425 if (!t_oop->is_known_instance() && load_boxed_values) {
1426 // Use _idx of address base for boxed values.
1427 this_iid = base->_idx;
1428 }
1429 PhaseIterGVN* igvn = phase->is_IterGVN();
1430 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1431 for (uint i = 1; i < region->req(); i++) {
1432 Node* x;
1433 Node* the_clone = NULL;
1434 if (region->in(i) == C->top()) {
1435 x = C->top(); // Dead path? Use a dead data op
1436 } else {
1437 x = this->clone(); // Else clone up the data op
1438 the_clone = x; // Remember for possible deletion.
1439 // Alter data node to use pre-phi inputs
1440 if (this->in(0) == region) {
1441 x->set_req(0, region->in(i));
1442 } else {
1443 x->set_req(0, NULL);
1444 }
1445 if (mem->is_Phi() && (mem->in(0) == region)) {
1446 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1447 }
1448 if (address->is_Phi() && address->in(0) == region) {
1449 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1450 }
1451 if (base_is_phi && (base->in(0) == region)) {
1452 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1453 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1454 x->set_req(Address, adr_x);
1455 }
1456 }
1457 // Check for a 'win' on some paths
1458 const Type *t = x->Value(igvn);
1459
1460 bool singleton = t->singleton();
1461
1462 // See comments in PhaseIdealLoop::split_thru_phi().
1463 if (singleton && t == Type::TOP) {
1464 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1465 }
1466
1467 if (singleton) {
1468 x = igvn->makecon(t);
1469 } else {
1470 // We now call Identity to try to simplify the cloned node.
1471 // Note that some Identity methods call phase->type(this).
1472 // Make sure that the type array is big enough for
1473 // our new node, even though we may throw the node away.
1474 // (This tweaking with igvn only works because x is a new node.)
1475 igvn->set_type(x, t);
1476 // If x is a TypeNode, capture any more-precise type permanently into Node
1477 // otherwise it will be not updated during igvn->transform since
1478 // igvn->type(x) is set to x->Value() already.
1479 x->raise_bottom_type(t);
1480 Node *y = x->Identity(igvn);
1481 if (y != x) {
1482 x = y;
1483 } else {
1484 y = igvn->hash_find_insert(x);
1485 if (y) {
1486 x = y;
1487 } else {
1488 // Else x is a new node we are keeping
1489 // We do not need register_new_node_with_optimizer
1490 // because set_type has already been called.
1491 igvn->_worklist.push(x);
1492 }
1493 }
1494 }
1495 if (x != the_clone && the_clone != NULL) {
1496 igvn->remove_dead_node(the_clone);
1497 }
1498 phi->set_req(i, x);
1499 }
1500 // Record Phi
1501 igvn->register_new_node_with_optimizer(phi);
1502 return phi;
1503 }
1504
1505 //------------------------------Ideal------------------------------------------
1506 // If the load is from Field memory and the pointer is non-null, it might be possible to
1507 // zero out the control input.
1508 // If the offset is constant and the base is an object allocation,
1509 // try to hook me up to the exact initializing store.
1510 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1511 Node* p = MemNode::Ideal_common(phase, can_reshape);
1512 if (p) return (p == NodeSentinel) ? NULL : p;
1513
1514 Node* ctrl = in(MemNode::Control);
1515 Node* address = in(MemNode::Address);
1516 bool progress = false;
1517
1518 // Skip up past a SafePoint control. Cannot do this for Stores because
1519 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1520 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1521 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1522 ctrl = ctrl->in(0);
1523 set_req(MemNode::Control,ctrl);
1524 progress = true;
1525 }
1526
1527 intptr_t ignore = 0;
1528 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1529 if (base != NULL
1530 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1531 // Check for useless control edge in some common special cases
1532 if (in(MemNode::Control) != NULL
1533 && can_remove_control()
1534 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1535 && all_controls_dominate(base, phase->C->start())) {
1536 // A method-invariant, non-null address (constant or 'this' argument).
1537 set_req(MemNode::Control, NULL);
1538 progress = true;
1539 }
1540 }
1541
1542 Node* mem = in(MemNode::Memory);
1543 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1544
1545 if (can_reshape && (addr_t != NULL)) {
1546 // try to optimize our memory input
1547 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1548 if (opt_mem != mem) {
1549 set_req(MemNode::Memory, opt_mem);
1550 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1551 return this;
1552 }
1553 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1554 if ((t_oop != NULL) &&
1555 (t_oop->is_known_instance_field() ||
1556 t_oop->is_ptr_to_boxed_value())) {
1557 PhaseIterGVN *igvn = phase->is_IterGVN();
1558 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1559 // Delay this transformation until memory Phi is processed.
1560 phase->is_IterGVN()->_worklist.push(this);
1561 return NULL;
1562 }
1563 // Split instance field load through Phi.
1564 Node* result = split_through_phi(phase);
1565 if (result != NULL) return result;
1566
1567 if (t_oop->is_ptr_to_boxed_value()) {
1568 Node* result = eliminate_autobox(phase);
1569 if (result != NULL) return result;
1570 }
1571 }
1572 }
1573
1574 // Is there a dominating load that loads the same value? Leave
1575 // anything that is not a load of a field/array element (like
1576 // barriers etc.) alone
1577 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1578 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1579 Node *use = mem->fast_out(i);
1580 if (use != this &&
1581 use->Opcode() == Opcode() &&
1582 use->in(0) != NULL &&
1583 use->in(0) != in(0) &&
1584 use->in(Address) == in(Address)) {
1585 Node* ctl = in(0);
1586 for (int i = 0; i < 10 && ctl != NULL; i++) {
1587 ctl = IfNode::up_one_dom(ctl);
1588 if (ctl == use->in(0)) {
1589 set_req(0, use->in(0));
1590 return this;
1591 }
1592 }
1593 }
1594 }
1595 }
1596
1597 // Check for prior store with a different base or offset; make Load
1598 // independent. Skip through any number of them. Bail out if the stores
1599 // are in an endless dead cycle and report no progress. This is a key
1600 // transform for Reflection. However, if after skipping through the Stores
1601 // we can't then fold up against a prior store do NOT do the transform as
1602 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1603 // array memory alive twice: once for the hoisted Load and again after the
1604 // bypassed Store. This situation only works if EVERYBODY who does
1605 // anti-dependence work knows how to bypass. I.e. we need all
1606 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1607 // the alias index stuff. So instead, peek through Stores and IFF we can
1608 // fold up, do so.
1609 Node* prev_mem = find_previous_store(phase);
1610 if (prev_mem != NULL) {
1611 Node* value = can_see_arraycopy_value(prev_mem, phase);
1612 if (value != NULL) {
1613 return value;
1614 }
1615 }
1616 // Steps (a), (b): Walk past independent stores to find an exact match.
1617 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1618 // (c) See if we can fold up on the spot, but don't fold up here.
1619 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1620 // just return a prior value, which is done by Identity calls.
1621 if (can_see_stored_value(prev_mem, phase)) {
1622 // Make ready for step (d):
1623 set_req(MemNode::Memory, prev_mem);
1624 return this;
1625 }
1626 }
1627
1628 return progress ? this : NULL;
1629 }
1630
1631 // Helper to recognize certain Klass fields which are invariant across
1632 // some group of array types (e.g., int[] or all T[] where T < Object).
1633 const Type*
1634 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1635 ciKlass* klass) const {
1636 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1637 // The field is Klass::_modifier_flags. Return its (constant) value.
1638 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1639 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1640 return TypeInt::make(klass->modifier_flags());
1641 }
1642 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1643 // The field is Klass::_access_flags. Return its (constant) value.
1644 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1645 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1646 return TypeInt::make(klass->access_flags());
1647 }
1648 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1649 // The field is Klass::_layout_helper. Return its constant value if known.
1650 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1651 return TypeInt::make(klass->layout_helper());
1652 }
1653
1654 // No match.
1655 return NULL;
1656 }
1657
1658 //------------------------------Value-----------------------------------------
1659 const Type* LoadNode::Value(PhaseGVN* phase) const {
1660 // Either input is TOP ==> the result is TOP
1661 Node* mem = in(MemNode::Memory);
1662 const Type *t1 = phase->type(mem);
1663 if (t1 == Type::TOP) return Type::TOP;
1664 Node* adr = in(MemNode::Address);
1665 const TypePtr* tp = phase->type(adr)->isa_ptr();
1666 if (tp == NULL || tp->empty()) return Type::TOP;
1667 int off = tp->offset();
1668 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1669 Compile* C = phase->C;
1670
1671 // Try to guess loaded type from pointer type
1672 if (tp->isa_aryptr()) {
1673 const TypeAryPtr* ary = tp->is_aryptr();
1674 const Type* t = ary->elem();
1675
1676 // Determine whether the reference is beyond the header or not, by comparing
1677 // the offset against the offset of the start of the array's data.
1678 // Different array types begin at slightly different offsets (12 vs. 16).
1679 // We choose T_BYTE as an example base type that is least restrictive
1680 // as to alignment, which will therefore produce the smallest
1681 // possible base offset.
1682 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1683 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1684
1685 // Try to constant-fold a stable array element.
1686 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1687 // Make sure the reference is not into the header and the offset is constant
1688 ciObject* aobj = ary->const_oop();
1689 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1690 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1691 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1692 stable_dimension,
1693 memory_type(), is_unsigned());
1694 if (con_type != NULL) {
1695 return con_type;
1696 }
1697 }
1698 }
1699
1700 // Don't do this for integer types. There is only potential profit if
1701 // the element type t is lower than _type; that is, for int types, if _type is
1702 // more restrictive than t. This only happens here if one is short and the other
1703 // char (both 16 bits), and in those cases we've made an intentional decision
1704 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1705 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1706 //
1707 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1708 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1709 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1710 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1711 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1712 // In fact, that could have been the original type of p1, and p1 could have
1713 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1714 // expression (LShiftL quux 3) independently optimized to the constant 8.
1715 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1716 && (_type->isa_vect() == NULL)
1717 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1718 // t might actually be lower than _type, if _type is a unique
1719 // concrete subclass of abstract class t.
1720 if (off_beyond_header) { // is the offset beyond the header?
1721 const Type* jt = t->join_speculative(_type);
1722 // In any case, do not allow the join, per se, to empty out the type.
1723 if (jt->empty() && !t->empty()) {
1724 // This can happen if a interface-typed array narrows to a class type.
1725 jt = _type;
1726 }
1727 #ifdef ASSERT
1728 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1729 // The pointers in the autobox arrays are always non-null
1730 Node* base = adr->in(AddPNode::Base);
1731 if ((base != NULL) && base->is_DecodeN()) {
1732 // Get LoadN node which loads IntegerCache.cache field
1733 base = base->in(1);
1734 }
1735 if ((base != NULL) && base->is_Con()) {
1736 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1737 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1738 // It could be narrow oop
1739 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1740 }
1741 }
1742 }
1743 #endif
1744 return jt;
1745 }
1746 }
1747 } else if (tp->base() == Type::InstPtr) {
1748 assert( off != Type::OffsetBot ||
1749 // arrays can be cast to Objects
1750 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1751 // unsafe field access may not have a constant offset
1752 C->has_unsafe_access(),
1753 "Field accesses must be precise" );
1754 // For oop loads, we expect the _type to be precise.
1755
1756 // Optimize loads from constant fields.
1757 const TypeInstPtr* tinst = tp->is_instptr();
1758 ciObject* const_oop = tinst->const_oop();
1759 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1760 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1761 if (con_type != NULL) {
1762 return con_type;
1763 }
1764 }
1765 } else if (tp->base() == Type::KlassPtr) {
1766 assert( off != Type::OffsetBot ||
1767 // arrays can be cast to Objects
1768 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1769 // also allow array-loading from the primary supertype
1770 // array during subtype checks
1771 Opcode() == Op_LoadKlass,
1772 "Field accesses must be precise" );
1773 // For klass/static loads, we expect the _type to be precise
1774 }
1775
1776 const TypeKlassPtr *tkls = tp->isa_klassptr();
1777 if (tkls != NULL && !StressReflectiveCode) {
1778 ciKlass* klass = tkls->klass();
1779 if (klass->is_loaded() && tkls->klass_is_exact()) {
1780 // We are loading a field from a Klass metaobject whose identity
1781 // is known at compile time (the type is "exact" or "precise").
1782 // Check for fields we know are maintained as constants by the VM.
1783 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1784 // The field is Klass::_super_check_offset. Return its (constant) value.
1785 // (Folds up type checking code.)
1786 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1787 return TypeInt::make(klass->super_check_offset());
1788 }
1789 // Compute index into primary_supers array
1790 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1791 // Check for overflowing; use unsigned compare to handle the negative case.
1792 if( depth < ciKlass::primary_super_limit() ) {
1793 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1794 // (Folds up type checking code.)
1795 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1796 ciKlass *ss = klass->super_of_depth(depth);
1797 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1798 }
1799 const Type* aift = load_array_final_field(tkls, klass);
1800 if (aift != NULL) return aift;
1801 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1802 // The field is Klass::_java_mirror. Return its (constant) value.
1803 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1804 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1805 return TypeInstPtr::make(klass->java_mirror());
1806 }
1807 }
1808
1809 // We can still check if we are loading from the primary_supers array at a
1810 // shallow enough depth. Even though the klass is not exact, entries less
1811 // than or equal to its super depth are correct.
1812 if (klass->is_loaded() ) {
1813 ciType *inner = klass;
1814 while( inner->is_obj_array_klass() )
1815 inner = inner->as_obj_array_klass()->base_element_type();
1816 if( inner->is_instance_klass() &&
1817 !inner->as_instance_klass()->flags().is_interface() ) {
1818 // Compute index into primary_supers array
1819 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1820 // Check for overflowing; use unsigned compare to handle the negative case.
1821 if( depth < ciKlass::primary_super_limit() &&
1822 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1823 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1824 // (Folds up type checking code.)
1825 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1826 ciKlass *ss = klass->super_of_depth(depth);
1827 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1828 }
1829 }
1830 }
1831
1832 // If the type is enough to determine that the thing is not an array,
1833 // we can give the layout_helper a positive interval type.
1834 // This will help short-circuit some reflective code.
1835 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1836 && !klass->is_array_klass() // not directly typed as an array
1837 && !klass->is_interface() // specifically not Serializable & Cloneable
1838 && !klass->is_java_lang_Object() // not the supertype of all T[]
1839 ) {
1840 // Note: When interfaces are reliable, we can narrow the interface
1841 // test to (klass != Serializable && klass != Cloneable).
1842 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1843 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1844 // The key property of this type is that it folds up tests
1845 // for array-ness, since it proves that the layout_helper is positive.
1846 // Thus, a generic value like the basic object layout helper works fine.
1847 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1848 }
1849 }
1850
1851 // If we are loading from a freshly-allocated object, produce a zero,
1852 // if the load is provably beyond the header of the object.
1853 // (Also allow a variable load from a fresh array to produce zero.)
1854 const TypeOopPtr *tinst = tp->isa_oopptr();
1855 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1856 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1857 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1858 Node* value = can_see_stored_value(mem,phase);
1859 if (value != NULL && value->is_Con()) {
1860 assert(value->bottom_type()->higher_equal(_type),"sanity");
1861 return value->bottom_type();
1862 }
1863 }
1864
1865 if (is_instance) {
1866 // If we have an instance type and our memory input is the
1867 // programs's initial memory state, there is no matching store,
1868 // so just return a zero of the appropriate type
1869 Node *mem = in(MemNode::Memory);
1870 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1871 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1872 return Type::get_zero_type(_type->basic_type());
1873 }
1874 }
1875 return _type;
1876 }
1877
1878 //------------------------------match_edge-------------------------------------
1879 // Do we Match on this edge index or not? Match only the address.
1880 uint LoadNode::match_edge(uint idx) const {
1881 return idx == MemNode::Address;
1882 }
1883
1884 //--------------------------LoadBNode::Ideal--------------------------------------
1885 //
1886 // If the previous store is to the same address as this load,
1887 // and the value stored was larger than a byte, replace this load
1888 // with the value stored truncated to a byte. If no truncation is
1889 // needed, the replacement is done in LoadNode::Identity().
1890 //
1891 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1892 Node* mem = in(MemNode::Memory);
1893 Node* value = can_see_stored_value(mem,phase);
1894 if( value && !phase->type(value)->higher_equal( _type ) ) {
1895 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1896 return new RShiftINode(result, phase->intcon(24));
1897 }
1898 // Identity call will handle the case where truncation is not needed.
1899 return LoadNode::Ideal(phase, can_reshape);
1900 }
1901
1902 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1903 Node* mem = in(MemNode::Memory);
1904 Node* value = can_see_stored_value(mem,phase);
1905 if (value != NULL && value->is_Con() &&
1906 !value->bottom_type()->higher_equal(_type)) {
1907 // If the input to the store does not fit with the load's result type,
1908 // it must be truncated. We can't delay until Ideal call since
1909 // a singleton Value is needed for split_thru_phi optimization.
1910 int con = value->get_int();
1911 return TypeInt::make((con << 24) >> 24);
1912 }
1913 return LoadNode::Value(phase);
1914 }
1915
1916 //--------------------------LoadUBNode::Ideal-------------------------------------
1917 //
1918 // If the previous store is to the same address as this load,
1919 // and the value stored was larger than a byte, replace this load
1920 // with the value stored truncated to a byte. If no truncation is
1921 // needed, the replacement is done in LoadNode::Identity().
1922 //
1923 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1924 Node* mem = in(MemNode::Memory);
1925 Node* value = can_see_stored_value(mem, phase);
1926 if (value && !phase->type(value)->higher_equal(_type))
1927 return new AndINode(value, phase->intcon(0xFF));
1928 // Identity call will handle the case where truncation is not needed.
1929 return LoadNode::Ideal(phase, can_reshape);
1930 }
1931
1932 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
1933 Node* mem = in(MemNode::Memory);
1934 Node* value = can_see_stored_value(mem,phase);
1935 if (value != NULL && value->is_Con() &&
1936 !value->bottom_type()->higher_equal(_type)) {
1937 // If the input to the store does not fit with the load's result type,
1938 // it must be truncated. We can't delay until Ideal call since
1939 // a singleton Value is needed for split_thru_phi optimization.
1940 int con = value->get_int();
1941 return TypeInt::make(con & 0xFF);
1942 }
1943 return LoadNode::Value(phase);
1944 }
1945
1946 //--------------------------LoadUSNode::Ideal-------------------------------------
1947 //
1948 // If the previous store is to the same address as this load,
1949 // and the value stored was larger than a char, replace this load
1950 // with the value stored truncated to a char. If no truncation is
1951 // needed, the replacement is done in LoadNode::Identity().
1952 //
1953 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1954 Node* mem = in(MemNode::Memory);
1955 Node* value = can_see_stored_value(mem,phase);
1956 if( value && !phase->type(value)->higher_equal( _type ) )
1957 return new AndINode(value,phase->intcon(0xFFFF));
1958 // Identity call will handle the case where truncation is not needed.
1959 return LoadNode::Ideal(phase, can_reshape);
1960 }
1961
1962 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
1963 Node* mem = in(MemNode::Memory);
1964 Node* value = can_see_stored_value(mem,phase);
1965 if (value != NULL && value->is_Con() &&
1966 !value->bottom_type()->higher_equal(_type)) {
1967 // If the input to the store does not fit with the load's result type,
1968 // it must be truncated. We can't delay until Ideal call since
1969 // a singleton Value is needed for split_thru_phi optimization.
1970 int con = value->get_int();
1971 return TypeInt::make(con & 0xFFFF);
1972 }
1973 return LoadNode::Value(phase);
1974 }
1975
1976 //--------------------------LoadSNode::Ideal--------------------------------------
1977 //
1978 // If the previous store is to the same address as this load,
1979 // and the value stored was larger than a short, replace this load
1980 // with the value stored truncated to a short. If no truncation is
1981 // needed, the replacement is done in LoadNode::Identity().
1982 //
1983 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1984 Node* mem = in(MemNode::Memory);
1985 Node* value = can_see_stored_value(mem,phase);
1986 if( value && !phase->type(value)->higher_equal( _type ) ) {
1987 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
1988 return new RShiftINode(result, phase->intcon(16));
1989 }
1990 // Identity call will handle the case where truncation is not needed.
1991 return LoadNode::Ideal(phase, can_reshape);
1992 }
1993
1994 const Type* LoadSNode::Value(PhaseGVN* phase) const {
1995 Node* mem = in(MemNode::Memory);
1996 Node* value = can_see_stored_value(mem,phase);
1997 if (value != NULL && value->is_Con() &&
1998 !value->bottom_type()->higher_equal(_type)) {
1999 // If the input to the store does not fit with the load's result type,
2000 // it must be truncated. We can't delay until Ideal call since
2001 // a singleton Value is needed for split_thru_phi optimization.
2002 int con = value->get_int();
2003 return TypeInt::make((con << 16) >> 16);
2004 }
2005 return LoadNode::Value(phase);
2006 }
2007
2008 //=============================================================================
2009 //----------------------------LoadKlassNode::make------------------------------
2010 // Polymorphic factory method:
2011 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2012 // sanity check the alias category against the created node type
2013 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2014 assert(adr_type != NULL, "expecting TypeKlassPtr");
2015 #ifdef _LP64
2016 if (adr_type->is_ptr_to_narrowklass()) {
2017 assert(UseCompressedClassPointers, "no compressed klasses");
2018 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2019 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2020 }
2021 #endif
2022 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2023 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2024 }
2025
2026 //------------------------------Value------------------------------------------
2027 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2028 return klass_value_common(phase);
2029 }
2030
2031 // In most cases, LoadKlassNode does not have the control input set. If the control
2032 // input is set, it must not be removed (by LoadNode::Ideal()).
2033 bool LoadKlassNode::can_remove_control() const {
2034 return false;
2035 }
2036
2037 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2038 // Either input is TOP ==> the result is TOP
2039 const Type *t1 = phase->type( in(MemNode::Memory) );
2040 if (t1 == Type::TOP) return Type::TOP;
2041 Node *adr = in(MemNode::Address);
2042 const Type *t2 = phase->type( adr );
2043 if (t2 == Type::TOP) return Type::TOP;
2044 const TypePtr *tp = t2->is_ptr();
2045 if (TypePtr::above_centerline(tp->ptr()) ||
2046 tp->ptr() == TypePtr::Null) return Type::TOP;
2047
2048 // Return a more precise klass, if possible
2049 const TypeInstPtr *tinst = tp->isa_instptr();
2050 if (tinst != NULL) {
2051 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2052 int offset = tinst->offset();
2053 if (ik == phase->C->env()->Class_klass()
2054 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2055 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2056 // We are loading a special hidden field from a Class mirror object,
2057 // the field which points to the VM's Klass metaobject.
2058 ciType* t = tinst->java_mirror_type();
2059 // java_mirror_type returns non-null for compile-time Class constants.
2060 if (t != NULL) {
2061 // constant oop => constant klass
2062 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2063 if (t->is_void()) {
2064 // We cannot create a void array. Since void is a primitive type return null
2065 // klass. Users of this result need to do a null check on the returned klass.
2066 return TypePtr::NULL_PTR;
2067 }
2068 return TypeKlassPtr::make(ciArrayKlass::make(t));
2069 }
2070 if (!t->is_klass()) {
2071 // a primitive Class (e.g., int.class) has NULL for a klass field
2072 return TypePtr::NULL_PTR;
2073 }
2074 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2075 return TypeKlassPtr::make(t->as_klass());
2076 }
2077 // non-constant mirror, so we can't tell what's going on
2078 }
2079 if( !ik->is_loaded() )
2080 return _type; // Bail out if not loaded
2081 if (offset == oopDesc::klass_offset_in_bytes()) {
2082 if (tinst->klass_is_exact()) {
2083 return TypeKlassPtr::make(ik);
2084 }
2085 // See if we can become precise: no subklasses and no interface
2086 // (Note: We need to support verified interfaces.)
2087 if (!ik->is_interface() && !ik->has_subklass()) {
2088 //assert(!UseExactTypes, "this code should be useless with exact types");
2089 // Add a dependence; if any subclass added we need to recompile
2090 if (!ik->is_final()) {
2091 // %%% should use stronger assert_unique_concrete_subtype instead
2092 phase->C->dependencies()->assert_leaf_type(ik);
2093 }
2094 // Return precise klass
2095 return TypeKlassPtr::make(ik);
2096 }
2097
2098 // Return root of possible klass
2099 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2100 }
2101 }
2102
2103 // Check for loading klass from an array
2104 const TypeAryPtr *tary = tp->isa_aryptr();
2105 if( tary != NULL ) {
2106 ciKlass *tary_klass = tary->klass();
2107 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2108 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2109 if (tary->klass_is_exact()) {
2110 return TypeKlassPtr::make(tary_klass);
2111 }
2112 ciArrayKlass *ak = tary->klass()->as_array_klass();
2113 // If the klass is an object array, we defer the question to the
2114 // array component klass.
2115 if( ak->is_obj_array_klass() ) {
2116 assert( ak->is_loaded(), "" );
2117 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2118 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2119 ciInstanceKlass* ik = base_k->as_instance_klass();
2120 // See if we can become precise: no subklasses and no interface
2121 if (!ik->is_interface() && !ik->has_subklass()) {
2122 //assert(!UseExactTypes, "this code should be useless with exact types");
2123 // Add a dependence; if any subclass added we need to recompile
2124 if (!ik->is_final()) {
2125 phase->C->dependencies()->assert_leaf_type(ik);
2126 }
2127 // Return precise array klass
2128 return TypeKlassPtr::make(ak);
2129 }
2130 }
2131 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2132 } else { // Found a type-array?
2133 //assert(!UseExactTypes, "this code should be useless with exact types");
2134 assert( ak->is_type_array_klass(), "" );
2135 return TypeKlassPtr::make(ak); // These are always precise
2136 }
2137 }
2138 }
2139
2140 // Check for loading klass from an array klass
2141 const TypeKlassPtr *tkls = tp->isa_klassptr();
2142 if (tkls != NULL && !StressReflectiveCode) {
2143 ciKlass* klass = tkls->klass();
2144 if( !klass->is_loaded() )
2145 return _type; // Bail out if not loaded
2146 if( klass->is_obj_array_klass() &&
2147 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2148 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2149 // // Always returning precise element type is incorrect,
2150 // // e.g., element type could be object and array may contain strings
2151 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2152
2153 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2154 // according to the element type's subclassing.
2155 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2156 }
2157 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2158 tkls->offset() == in_bytes(Klass::super_offset())) {
2159 ciKlass* sup = klass->as_instance_klass()->super();
2160 // The field is Klass::_super. Return its (constant) value.
2161 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2162 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2163 }
2164 }
2165
2166 // Bailout case
2167 return LoadNode::Value(phase);
2168 }
2169
2170 //------------------------------Identity---------------------------------------
2171 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2172 // Also feed through the klass in Allocate(...klass...)._klass.
2173 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2174 return klass_identity_common(phase);
2175 }
2176
2177 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2178 Node* x = LoadNode::Identity(phase);
2179 if (x != this) return x;
2180
2181 // Take apart the address into an oop and and offset.
2182 // Return 'this' if we cannot.
2183 Node* adr = in(MemNode::Address);
2184 intptr_t offset = 0;
2185 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2186 if (base == NULL) return this;
2187 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2188 if (toop == NULL) return this;
2189
2190 // We can fetch the klass directly through an AllocateNode.
2191 // This works even if the klass is not constant (clone or newArray).
2192 if (offset == oopDesc::klass_offset_in_bytes()) {
2193 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2194 if (allocated_klass != NULL) {
2195 return allocated_klass;
2196 }
2197 }
2198
2199 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2200 // See inline_native_Class_query for occurrences of these patterns.
2201 // Java Example: x.getClass().isAssignableFrom(y)
2202 //
2203 // This improves reflective code, often making the Class
2204 // mirror go completely dead. (Current exception: Class
2205 // mirrors may appear in debug info, but we could clean them out by
2206 // introducing a new debug info operator for Klass*.java_mirror).
2207 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2208 && offset == java_lang_Class::klass_offset_in_bytes()) {
2209 // We are loading a special hidden field from a Class mirror,
2210 // the field which points to its Klass or ArrayKlass metaobject.
2211 if (base->is_Load()) {
2212 Node* adr2 = base->in(MemNode::Address);
2213 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2214 if (tkls != NULL && !tkls->empty()
2215 && (tkls->klass()->is_instance_klass() ||
2216 tkls->klass()->is_array_klass())
2217 && adr2->is_AddP()
2218 ) {
2219 int mirror_field = in_bytes(Klass::java_mirror_offset());
2220 if (tkls->offset() == mirror_field) {
2221 return adr2->in(AddPNode::Base);
2222 }
2223 }
2224 }
2225 }
2226
2227 return this;
2228 }
2229
2230
2231 //------------------------------Value------------------------------------------
2232 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2233 const Type *t = klass_value_common(phase);
2234 if (t == Type::TOP)
2235 return t;
2236
2237 return t->make_narrowklass();
2238 }
2239
2240 //------------------------------Identity---------------------------------------
2241 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2242 // Also feed through the klass in Allocate(...klass...)._klass.
2243 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2244 Node *x = klass_identity_common(phase);
2245
2246 const Type *t = phase->type( x );
2247 if( t == Type::TOP ) return x;
2248 if( t->isa_narrowklass()) return x;
2249 assert (!t->isa_narrowoop(), "no narrow oop here");
2250
2251 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2252 }
2253
2254 //------------------------------Value-----------------------------------------
2255 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2256 // Either input is TOP ==> the result is TOP
2257 const Type *t1 = phase->type( in(MemNode::Memory) );
2258 if( t1 == Type::TOP ) return Type::TOP;
2259 Node *adr = in(MemNode::Address);
2260 const Type *t2 = phase->type( adr );
2261 if( t2 == Type::TOP ) return Type::TOP;
2262 const TypePtr *tp = t2->is_ptr();
2263 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2264 const TypeAryPtr *tap = tp->isa_aryptr();
2265 if( !tap ) return _type;
2266 return tap->size();
2267 }
2268
2269 //-------------------------------Ideal---------------------------------------
2270 // Feed through the length in AllocateArray(...length...)._length.
2271 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2272 Node* p = MemNode::Ideal_common(phase, can_reshape);
2273 if (p) return (p == NodeSentinel) ? NULL : p;
2274
2275 // Take apart the address into an oop and and offset.
2276 // Return 'this' if we cannot.
2277 Node* adr = in(MemNode::Address);
2278 intptr_t offset = 0;
2279 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2280 if (base == NULL) return NULL;
2281 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2282 if (tary == NULL) return NULL;
2283
2284 // We can fetch the length directly through an AllocateArrayNode.
2285 // This works even if the length is not constant (clone or newArray).
2286 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2287 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2288 if (alloc != NULL) {
2289 Node* allocated_length = alloc->Ideal_length();
2290 Node* len = alloc->make_ideal_length(tary, phase);
2291 if (allocated_length != len) {
2292 // New CastII improves on this.
2293 return len;
2294 }
2295 }
2296 }
2297
2298 return NULL;
2299 }
2300
2301 //------------------------------Identity---------------------------------------
2302 // Feed through the length in AllocateArray(...length...)._length.
2303 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2304 Node* x = LoadINode::Identity(phase);
2305 if (x != this) return x;
2306
2307 // Take apart the address into an oop and and offset.
2308 // Return 'this' if we cannot.
2309 Node* adr = in(MemNode::Address);
2310 intptr_t offset = 0;
2311 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2312 if (base == NULL) return this;
2313 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2314 if (tary == NULL) return this;
2315
2316 // We can fetch the length directly through an AllocateArrayNode.
2317 // This works even if the length is not constant (clone or newArray).
2318 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2319 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2320 if (alloc != NULL) {
2321 Node* allocated_length = alloc->Ideal_length();
2322 // Do not allow make_ideal_length to allocate a CastII node.
2323 Node* len = alloc->make_ideal_length(tary, phase, false);
2324 if (allocated_length == len) {
2325 // Return allocated_length only if it would not be improved by a CastII.
2326 return allocated_length;
2327 }
2328 }
2329 }
2330
2331 return this;
2332
2333 }
2334
2335 //=============================================================================
2336 //---------------------------StoreNode::make-----------------------------------
2337 // Polymorphic factory method:
2338 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2339 assert((mo == unordered || mo == release), "unexpected");
2340 Compile* C = gvn.C;
2341 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2342 ctl != NULL, "raw memory operations should have control edge");
2343
2344 switch (bt) {
2345 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2346 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2347 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2348 case T_CHAR:
2349 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2350 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2351 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2352 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2353 case T_METADATA:
2354 case T_ADDRESS:
2355 case T_OBJECT:
2356 #ifdef _LP64
2357 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2358 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2359 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2360 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2361 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2362 adr->bottom_type()->isa_rawptr())) {
2363 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2364 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2365 }
2366 #endif
2367 {
2368 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2369 }
2370 default:
2371 ShouldNotReachHere();
2372 return (StoreNode*)NULL;
2373 }
2374 }
2375
2376 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2377 bool require_atomic = true;
2378 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2379 }
2380
2381 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2382 bool require_atomic = true;
2383 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2384 }
2385
2386
2387 //--------------------------bottom_type----------------------------------------
2388 const Type *StoreNode::bottom_type() const {
2389 return Type::MEMORY;
2390 }
2391
2392 //------------------------------hash-------------------------------------------
2393 uint StoreNode::hash() const {
2394 // unroll addition of interesting fields
2395 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2396
2397 // Since they are not commoned, do not hash them:
2398 return NO_HASH;
2399 }
2400
2401 //------------------------------Ideal------------------------------------------
2402 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2403 // When a store immediately follows a relevant allocation/initialization,
2404 // try to capture it into the initialization, or hoist it above.
2405 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2406 Node* p = MemNode::Ideal_common(phase, can_reshape);
2407 if (p) return (p == NodeSentinel) ? NULL : p;
2408
2409 Node* mem = in(MemNode::Memory);
2410 Node* address = in(MemNode::Address);
2411 // Back-to-back stores to same address? Fold em up. Generally
2412 // unsafe if I have intervening uses... Also disallowed for StoreCM
2413 // since they must follow each StoreP operation. Redundant StoreCMs
2414 // are eliminated just before matching in final_graph_reshape.
2415 {
2416 Node* st = mem;
2417 // If Store 'st' has more than one use, we cannot fold 'st' away.
2418 // For example, 'st' might be the final state at a conditional
2419 // return. Or, 'st' might be used by some node which is live at
2420 // the same time 'st' is live, which might be unschedulable. So,
2421 // require exactly ONE user until such time as we clone 'mem' for
2422 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2423 // true).
2424 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2425 // Looking at a dead closed cycle of memory?
2426 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2427 assert(Opcode() == st->Opcode() ||
2428 st->Opcode() == Op_StoreVector ||
2429 Opcode() == Op_StoreVector ||
2430 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2431 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2432 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2433 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2434 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2435
2436 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2437 st->as_Store()->memory_size() <= this->memory_size()) {
2438 Node* use = st->raw_out(0);
2439 phase->igvn_rehash_node_delayed(use);
2440 if (can_reshape) {
2441 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2442 } else {
2443 // It's OK to do this in the parser, since DU info is always accurate,
2444 // and the parser always refers to nodes via SafePointNode maps.
2445 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2446 }
2447 return this;
2448 }
2449 st = st->in(MemNode::Memory);
2450 }
2451 }
2452
2453
2454 // Capture an unaliased, unconditional, simple store into an initializer.
2455 // Or, if it is independent of the allocation, hoist it above the allocation.
2456 if (ReduceFieldZeroing && /*can_reshape &&*/
2457 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2458 InitializeNode* init = mem->in(0)->as_Initialize();
2459 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2460 if (offset > 0) {
2461 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2462 // If the InitializeNode captured me, it made a raw copy of me,
2463 // and I need to disappear.
2464 if (moved != NULL) {
2465 // %%% hack to ensure that Ideal returns a new node:
2466 mem = MergeMemNode::make(mem);
2467 return mem; // fold me away
2468 }
2469 }
2470 }
2471
2472 return NULL; // No further progress
2473 }
2474
2475 //------------------------------Value-----------------------------------------
2476 const Type* StoreNode::Value(PhaseGVN* phase) const {
2477 // Either input is TOP ==> the result is TOP
2478 const Type *t1 = phase->type( in(MemNode::Memory) );
2479 if( t1 == Type::TOP ) return Type::TOP;
2480 const Type *t2 = phase->type( in(MemNode::Address) );
2481 if( t2 == Type::TOP ) return Type::TOP;
2482 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2483 if( t3 == Type::TOP ) return Type::TOP;
2484 return Type::MEMORY;
2485 }
2486
2487 //------------------------------Identity---------------------------------------
2488 // Remove redundant stores:
2489 // Store(m, p, Load(m, p)) changes to m.
2490 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2491 Node* StoreNode::Identity(PhaseGVN* phase) {
2492 Node* mem = in(MemNode::Memory);
2493 Node* adr = in(MemNode::Address);
2494 Node* val = in(MemNode::ValueIn);
2495
2496 // Load then Store? Then the Store is useless
2497 if (val->is_Load() &&
2498 val->in(MemNode::Address)->eqv_uncast(adr) &&
2499 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2500 val->as_Load()->store_Opcode() == Opcode()) {
2501 return mem;
2502 }
2503
2504 // Two stores in a row of the same value?
2505 if (mem->is_Store() &&
2506 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2507 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2508 mem->Opcode() == Opcode()) {
2509 return mem;
2510 }
2511
2512 // Store of zero anywhere into a freshly-allocated object?
2513 // Then the store is useless.
2514 // (It must already have been captured by the InitializeNode.)
2515 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2516 // a newly allocated object is already all-zeroes everywhere
2517 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2518 return mem;
2519 }
2520
2521 // the store may also apply to zero-bits in an earlier object
2522 Node* prev_mem = find_previous_store(phase);
2523 // Steps (a), (b): Walk past independent stores to find an exact match.
2524 if (prev_mem != NULL) {
2525 Node* prev_val = can_see_stored_value(prev_mem, phase);
2526 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2527 // prev_val and val might differ by a cast; it would be good
2528 // to keep the more informative of the two.
2529 return mem;
2530 }
2531 }
2532 }
2533
2534 return this;
2535 }
2536
2537 //------------------------------match_edge-------------------------------------
2538 // Do we Match on this edge index or not? Match only memory & value
2539 uint StoreNode::match_edge(uint idx) const {
2540 return idx == MemNode::Address || idx == MemNode::ValueIn;
2541 }
2542
2543 //------------------------------cmp--------------------------------------------
2544 // Do not common stores up together. They generally have to be split
2545 // back up anyways, so do not bother.
2546 uint StoreNode::cmp( const Node &n ) const {
2547 return (&n == this); // Always fail except on self
2548 }
2549
2550 //------------------------------Ideal_masked_input-----------------------------
2551 // Check for a useless mask before a partial-word store
2552 // (StoreB ... (AndI valIn conIa) )
2553 // If (conIa & mask == mask) this simplifies to
2554 // (StoreB ... (valIn) )
2555 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2556 Node *val = in(MemNode::ValueIn);
2557 if( val->Opcode() == Op_AndI ) {
2558 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2559 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2560 set_req(MemNode::ValueIn, val->in(1));
2561 return this;
2562 }
2563 }
2564 return NULL;
2565 }
2566
2567
2568 //------------------------------Ideal_sign_extended_input----------------------
2569 // Check for useless sign-extension before a partial-word store
2570 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2571 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2572 // (StoreB ... (valIn) )
2573 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2574 Node *val = in(MemNode::ValueIn);
2575 if( val->Opcode() == Op_RShiftI ) {
2576 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2577 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2578 Node *shl = val->in(1);
2579 if( shl->Opcode() == Op_LShiftI ) {
2580 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2581 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2582 set_req(MemNode::ValueIn, shl->in(1));
2583 return this;
2584 }
2585 }
2586 }
2587 }
2588 return NULL;
2589 }
2590
2591 //------------------------------value_never_loaded-----------------------------------
2592 // Determine whether there are any possible loads of the value stored.
2593 // For simplicity, we actually check if there are any loads from the
2594 // address stored to, not just for loads of the value stored by this node.
2595 //
2596 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2597 Node *adr = in(Address);
2598 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2599 if (adr_oop == NULL)
2600 return false;
2601 if (!adr_oop->is_known_instance_field())
2602 return false; // if not a distinct instance, there may be aliases of the address
2603 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2604 Node *use = adr->fast_out(i);
2605 if (use->is_Load() || use->is_LoadStore()) {
2606 return false;
2607 }
2608 }
2609 return true;
2610 }
2611
2612 //=============================================================================
2613 //------------------------------Ideal------------------------------------------
2614 // If the store is from an AND mask that leaves the low bits untouched, then
2615 // we can skip the AND operation. If the store is from a sign-extension
2616 // (a left shift, then right shift) we can skip both.
2617 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2618 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2619 if( progress != NULL ) return progress;
2620
2621 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2622 if( progress != NULL ) return progress;
2623
2624 // Finally check the default case
2625 return StoreNode::Ideal(phase, can_reshape);
2626 }
2627
2628 //=============================================================================
2629 //------------------------------Ideal------------------------------------------
2630 // If the store is from an AND mask that leaves the low bits untouched, then
2631 // we can skip the AND operation
2632 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2633 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2634 if( progress != NULL ) return progress;
2635
2636 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2637 if( progress != NULL ) return progress;
2638
2639 // Finally check the default case
2640 return StoreNode::Ideal(phase, can_reshape);
2641 }
2642
2643 //=============================================================================
2644 //------------------------------Identity---------------------------------------
2645 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2646 // No need to card mark when storing a null ptr
2647 Node* my_store = in(MemNode::OopStore);
2648 if (my_store->is_Store()) {
2649 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2650 if( t1 == TypePtr::NULL_PTR ) {
2651 return in(MemNode::Memory);
2652 }
2653 }
2654 return this;
2655 }
2656
2657 //=============================================================================
2658 //------------------------------Ideal---------------------------------------
2659 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2660 Node* progress = StoreNode::Ideal(phase, can_reshape);
2661 if (progress != NULL) return progress;
2662
2663 Node* my_store = in(MemNode::OopStore);
2664 if (my_store->is_MergeMem()) {
2665 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2666 set_req(MemNode::OopStore, mem);
2667 return this;
2668 }
2669
2670 return NULL;
2671 }
2672
2673 //------------------------------Value-----------------------------------------
2674 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2675 // Either input is TOP ==> the result is TOP
2676 const Type *t = phase->type( in(MemNode::Memory) );
2677 if( t == Type::TOP ) return Type::TOP;
2678 t = phase->type( in(MemNode::Address) );
2679 if( t == Type::TOP ) return Type::TOP;
2680 t = phase->type( in(MemNode::ValueIn) );
2681 if( t == Type::TOP ) return Type::TOP;
2682 // If extra input is TOP ==> the result is TOP
2683 t = phase->type( in(MemNode::OopStore) );
2684 if( t == Type::TOP ) return Type::TOP;
2685
2686 return StoreNode::Value( phase );
2687 }
2688
2689
2690 //=============================================================================
2691 //----------------------------------SCMemProjNode------------------------------
2692 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2693 {
2694 return bottom_type();
2695 }
2696
2697 //=============================================================================
2698 //----------------------------------LoadStoreNode------------------------------
2699 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2700 : Node(required),
2701 _type(rt),
2702 _adr_type(at)
2703 {
2704 init_req(MemNode::Control, c );
2705 init_req(MemNode::Memory , mem);
2706 init_req(MemNode::Address, adr);
2707 init_req(MemNode::ValueIn, val);
2708 init_class_id(Class_LoadStore);
2709 }
2710
2711 uint LoadStoreNode::ideal_reg() const {
2712 return _type->ideal_reg();
2713 }
2714
2715 bool LoadStoreNode::result_not_used() const {
2716 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2717 Node *x = fast_out(i);
2718 if (x->Opcode() == Op_SCMemProj) continue;
2719 return false;
2720 }
2721 return true;
2722 }
2723
2724 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2725
2726 //=============================================================================
2727 //----------------------------------LoadStoreConditionalNode--------------------
2728 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2729 init_req(ExpectedIn, ex );
2730 }
2731
2732 //=============================================================================
2733 //-------------------------------adr_type--------------------------------------
2734 const TypePtr* ClearArrayNode::adr_type() const {
2735 Node *adr = in(3);
2736 if (adr == NULL) return NULL; // node is dead
2737 return MemNode::calculate_adr_type(adr->bottom_type());
2738 }
2739
2740 //------------------------------match_edge-------------------------------------
2741 // Do we Match on this edge index or not? Do not match memory
2742 uint ClearArrayNode::match_edge(uint idx) const {
2743 return idx > 1;
2744 }
2745
2746 //------------------------------Identity---------------------------------------
2747 // Clearing a zero length array does nothing
2748 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2749 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2750 }
2751
2752 //------------------------------Idealize---------------------------------------
2753 // Clearing a short array is faster with stores
2754 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2755 // Already know this is a large node, do not try to ideal it
2756 if (!IdealizeClearArrayNode || _is_large) return NULL;
2757
2758 const int unit = BytesPerLong;
2759 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2760 if (!t) return NULL;
2761 if (!t->is_con()) return NULL;
2762 intptr_t raw_count = t->get_con();
2763 intptr_t size = raw_count;
2764 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2765 // Clearing nothing uses the Identity call.
2766 // Negative clears are possible on dead ClearArrays
2767 // (see jck test stmt114.stmt11402.val).
2768 if (size <= 0 || size % unit != 0) return NULL;
2769 intptr_t count = size / unit;
2770 // Length too long; communicate this to matchers and assemblers.
2771 // Assemblers are responsible to produce fast hardware clears for it.
2772 if (size > InitArrayShortSize) {
2773 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2774 }
2775 Node *mem = in(1);
2776 if( phase->type(mem)==Type::TOP ) return NULL;
2777 Node *adr = in(3);
2778 const Type* at = phase->type(adr);
2779 if( at==Type::TOP ) return NULL;
2780 const TypePtr* atp = at->isa_ptr();
2781 // adjust atp to be the correct array element address type
2782 if (atp == NULL) atp = TypePtr::BOTTOM;
2783 else atp = atp->add_offset(Type::OffsetBot);
2784 // Get base for derived pointer purposes
2785 if( adr->Opcode() != Op_AddP ) Unimplemented();
2786 Node *base = adr->in(1);
2787
2788 Node *zero = phase->makecon(TypeLong::ZERO);
2789 Node *off = phase->MakeConX(BytesPerLong);
2790 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2791 count--;
2792 while( count-- ) {
2793 mem = phase->transform(mem);
2794 adr = phase->transform(new AddPNode(base,adr,off));
2795 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2796 }
2797 return mem;
2798 }
2799
2800 //----------------------------step_through----------------------------------
2801 // Return allocation input memory edge if it is different instance
2802 // or itself if it is the one we are looking for.
2803 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2804 Node* n = *np;
2805 assert(n->is_ClearArray(), "sanity");
2806 intptr_t offset;
2807 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2808 // This method is called only before Allocate nodes are expanded
2809 // during macro nodes expansion. Before that ClearArray nodes are
2810 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2811 // Allocate nodes are expanded) which follows allocations.
2812 assert(alloc != NULL, "should have allocation");
2813 if (alloc->_idx == instance_id) {
2814 // Can not bypass initialization of the instance we are looking for.
2815 return false;
2816 }
2817 // Otherwise skip it.
2818 InitializeNode* init = alloc->initialization();
2819 if (init != NULL)
2820 *np = init->in(TypeFunc::Memory);
2821 else
2822 *np = alloc->in(TypeFunc::Memory);
2823 return true;
2824 }
2825
2826 //----------------------------clear_memory-------------------------------------
2827 // Generate code to initialize object storage to zero.
2828 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2829 intptr_t start_offset,
2830 Node* end_offset,
2831 PhaseGVN* phase) {
2832 intptr_t offset = start_offset;
2833
2834 int unit = BytesPerLong;
2835 if ((offset % unit) != 0) {
2836 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2837 adr = phase->transform(adr);
2838 const TypePtr* atp = TypeRawPtr::BOTTOM;
2839 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2840 mem = phase->transform(mem);
2841 offset += BytesPerInt;
2842 }
2843 assert((offset % unit) == 0, "");
2844
2845 // Initialize the remaining stuff, if any, with a ClearArray.
2846 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2847 }
2848
2849 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2850 Node* start_offset,
2851 Node* end_offset,
2852 PhaseGVN* phase) {
2853 if (start_offset == end_offset) {
2854 // nothing to do
2855 return mem;
2856 }
2857
2858 int unit = BytesPerLong;
2859 Node* zbase = start_offset;
2860 Node* zend = end_offset;
2861
2862 // Scale to the unit required by the CPU:
2863 if (!Matcher::init_array_count_is_in_bytes) {
2864 Node* shift = phase->intcon(exact_log2(unit));
2865 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2866 zend = phase->transform(new URShiftXNode(zend, shift) );
2867 }
2868
2869 // Bulk clear double-words
2870 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2871 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2872 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
2873 return phase->transform(mem);
2874 }
2875
2876 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2877 intptr_t start_offset,
2878 intptr_t end_offset,
2879 PhaseGVN* phase) {
2880 if (start_offset == end_offset) {
2881 // nothing to do
2882 return mem;
2883 }
2884
2885 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2886 intptr_t done_offset = end_offset;
2887 if ((done_offset % BytesPerLong) != 0) {
2888 done_offset -= BytesPerInt;
2889 }
2890 if (done_offset > start_offset) {
2891 mem = clear_memory(ctl, mem, dest,
2892 start_offset, phase->MakeConX(done_offset), phase);
2893 }
2894 if (done_offset < end_offset) { // emit the final 32-bit store
2895 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2896 adr = phase->transform(adr);
2897 const TypePtr* atp = TypeRawPtr::BOTTOM;
2898 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2899 mem = phase->transform(mem);
2900 done_offset += BytesPerInt;
2901 }
2902 assert(done_offset == end_offset, "");
2903 return mem;
2904 }
2905
2906 //=============================================================================
2907 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2908 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2909 _adr_type(C->get_adr_type(alias_idx))
2910 {
2911 init_class_id(Class_MemBar);
2912 Node* top = C->top();
2913 init_req(TypeFunc::I_O,top);
2914 init_req(TypeFunc::FramePtr,top);
2915 init_req(TypeFunc::ReturnAdr,top);
2916 if (precedent != NULL)
2917 init_req(TypeFunc::Parms, precedent);
2918 }
2919
2920 //------------------------------cmp--------------------------------------------
2921 uint MemBarNode::hash() const { return NO_HASH; }
2922 uint MemBarNode::cmp( const Node &n ) const {
2923 return (&n == this); // Always fail except on self
2924 }
2925
2926 //------------------------------make-------------------------------------------
2927 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2928 switch (opcode) {
2929 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2930 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2931 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2932 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2933 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2934 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2935 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2936 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2937 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
2938 case Op_Initialize: return new InitializeNode(C, atp, pn);
2939 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2940 default: ShouldNotReachHere(); return NULL;
2941 }
2942 }
2943
2944 //------------------------------Ideal------------------------------------------
2945 // Return a node which is more "ideal" than the current node. Strip out
2946 // control copies
2947 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2948 if (remove_dead_region(phase, can_reshape)) return this;
2949 // Don't bother trying to transform a dead node
2950 if (in(0) && in(0)->is_top()) {
2951 return NULL;
2952 }
2953
2954 bool progress = false;
2955 // Eliminate volatile MemBars for scalar replaced objects.
2956 if (can_reshape && req() == (Precedent+1)) {
2957 bool eliminate = false;
2958 int opc = Opcode();
2959 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2960 // Volatile field loads and stores.
2961 Node* my_mem = in(MemBarNode::Precedent);
2962 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2963 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2964 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2965 // replace this Precedent (decodeN) with the Load instead.
2966 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2967 Node* load_node = my_mem->in(1);
2968 set_req(MemBarNode::Precedent, load_node);
2969 phase->is_IterGVN()->_worklist.push(my_mem);
2970 my_mem = load_node;
2971 } else {
2972 assert(my_mem->unique_out() == this, "sanity");
2973 del_req(Precedent);
2974 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2975 my_mem = NULL;
2976 }
2977 progress = true;
2978 }
2979 if (my_mem != NULL && my_mem->is_Mem()) {
2980 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2981 // Check for scalar replaced object reference.
2982 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2983 t_oop->offset() != Type::OffsetBot &&
2984 t_oop->offset() != Type::OffsetTop) {
2985 eliminate = true;
2986 }
2987 }
2988 } else if (opc == Op_MemBarRelease) {
2989 // Final field stores.
2990 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2991 if ((alloc != NULL) && alloc->is_Allocate() &&
2992 alloc->as_Allocate()->does_not_escape_thread()) {
2993 // The allocated object does not escape.
2994 eliminate = true;
2995 }
2996 }
2997 if (eliminate) {
2998 // Replace MemBar projections by its inputs.
2999 PhaseIterGVN* igvn = phase->is_IterGVN();
3000 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3001 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3002 // Must return either the original node (now dead) or a new node
3003 // (Do not return a top here, since that would break the uniqueness of top.)
3004 return new ConINode(TypeInt::ZERO);
3005 }
3006 }
3007 return progress ? this : NULL;
3008 }
3009
3010 //------------------------------Value------------------------------------------
3011 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3012 if( !in(0) ) return Type::TOP;
3013 if( phase->type(in(0)) == Type::TOP )
3014 return Type::TOP;
3015 return TypeTuple::MEMBAR;
3016 }
3017
3018 //------------------------------match------------------------------------------
3019 // Construct projections for memory.
3020 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3021 switch (proj->_con) {
3022 case TypeFunc::Control:
3023 case TypeFunc::Memory:
3024 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3025 }
3026 ShouldNotReachHere();
3027 return NULL;
3028 }
3029
3030 //===========================InitializeNode====================================
3031 // SUMMARY:
3032 // This node acts as a memory barrier on raw memory, after some raw stores.
3033 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3034 // The Initialize can 'capture' suitably constrained stores as raw inits.
3035 // It can coalesce related raw stores into larger units (called 'tiles').
3036 // It can avoid zeroing new storage for memory units which have raw inits.
3037 // At macro-expansion, it is marked 'complete', and does not optimize further.
3038 //
3039 // EXAMPLE:
3040 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3041 // ctl = incoming control; mem* = incoming memory
3042 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3043 // First allocate uninitialized memory and fill in the header:
3044 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3045 // ctl := alloc.Control; mem* := alloc.Memory*
3046 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3047 // Then initialize to zero the non-header parts of the raw memory block:
3048 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3049 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3050 // After the initialize node executes, the object is ready for service:
3051 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3052 // Suppose its body is immediately initialized as {1,2}:
3053 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3054 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3055 // mem.SLICE(#short[*]) := store2
3056 //
3057 // DETAILS:
3058 // An InitializeNode collects and isolates object initialization after
3059 // an AllocateNode and before the next possible safepoint. As a
3060 // memory barrier (MemBarNode), it keeps critical stores from drifting
3061 // down past any safepoint or any publication of the allocation.
3062 // Before this barrier, a newly-allocated object may have uninitialized bits.
3063 // After this barrier, it may be treated as a real oop, and GC is allowed.
3064 //
3065 // The semantics of the InitializeNode include an implicit zeroing of
3066 // the new object from object header to the end of the object.
3067 // (The object header and end are determined by the AllocateNode.)
3068 //
3069 // Certain stores may be added as direct inputs to the InitializeNode.
3070 // These stores must update raw memory, and they must be to addresses
3071 // derived from the raw address produced by AllocateNode, and with
3072 // a constant offset. They must be ordered by increasing offset.
3073 // The first one is at in(RawStores), the last at in(req()-1).
3074 // Unlike most memory operations, they are not linked in a chain,
3075 // but are displayed in parallel as users of the rawmem output of
3076 // the allocation.
3077 //
3078 // (See comments in InitializeNode::capture_store, which continue
3079 // the example given above.)
3080 //
3081 // When the associated Allocate is macro-expanded, the InitializeNode
3082 // may be rewritten to optimize collected stores. A ClearArrayNode
3083 // may also be created at that point to represent any required zeroing.
3084 // The InitializeNode is then marked 'complete', prohibiting further
3085 // capturing of nearby memory operations.
3086 //
3087 // During macro-expansion, all captured initializations which store
3088 // constant values of 32 bits or smaller are coalesced (if advantageous)
3089 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3090 // initialized in fewer memory operations. Memory words which are
3091 // covered by neither tiles nor non-constant stores are pre-zeroed
3092 // by explicit stores of zero. (The code shape happens to do all
3093 // zeroing first, then all other stores, with both sequences occurring
3094 // in order of ascending offsets.)
3095 //
3096 // Alternatively, code may be inserted between an AllocateNode and its
3097 // InitializeNode, to perform arbitrary initialization of the new object.
3098 // E.g., the object copying intrinsics insert complex data transfers here.
3099 // The initialization must then be marked as 'complete' disable the
3100 // built-in zeroing semantics and the collection of initializing stores.
3101 //
3102 // While an InitializeNode is incomplete, reads from the memory state
3103 // produced by it are optimizable if they match the control edge and
3104 // new oop address associated with the allocation/initialization.
3105 // They return a stored value (if the offset matches) or else zero.
3106 // A write to the memory state, if it matches control and address,
3107 // and if it is to a constant offset, may be 'captured' by the
3108 // InitializeNode. It is cloned as a raw memory operation and rewired
3109 // inside the initialization, to the raw oop produced by the allocation.
3110 // Operations on addresses which are provably distinct (e.g., to
3111 // other AllocateNodes) are allowed to bypass the initialization.
3112 //
3113 // The effect of all this is to consolidate object initialization
3114 // (both arrays and non-arrays, both piecewise and bulk) into a
3115 // single location, where it can be optimized as a unit.
3116 //
3117 // Only stores with an offset less than TrackedInitializationLimit words
3118 // will be considered for capture by an InitializeNode. This puts a
3119 // reasonable limit on the complexity of optimized initializations.
3120
3121 //---------------------------InitializeNode------------------------------------
3122 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3123 : _is_complete(Incomplete), _does_not_escape(false),
3124 MemBarNode(C, adr_type, rawoop)
3125 {
3126 init_class_id(Class_Initialize);
3127
3128 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3129 assert(in(RawAddress) == rawoop, "proper init");
3130 // Note: allocation() can be NULL, for secondary initialization barriers
3131 }
3132
3133 // Since this node is not matched, it will be processed by the
3134 // register allocator. Declare that there are no constraints
3135 // on the allocation of the RawAddress edge.
3136 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3137 // This edge should be set to top, by the set_complete. But be conservative.
3138 if (idx == InitializeNode::RawAddress)
3139 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3140 return RegMask::Empty;
3141 }
3142
3143 Node* InitializeNode::memory(uint alias_idx) {
3144 Node* mem = in(Memory);
3145 if (mem->is_MergeMem()) {
3146 return mem->as_MergeMem()->memory_at(alias_idx);
3147 } else {
3148 // incoming raw memory is not split
3149 return mem;
3150 }
3151 }
3152
3153 bool InitializeNode::is_non_zero() {
3154 if (is_complete()) return false;
3155 remove_extra_zeroes();
3156 return (req() > RawStores);
3157 }
3158
3159 void InitializeNode::set_complete(PhaseGVN* phase) {
3160 assert(!is_complete(), "caller responsibility");
3161 _is_complete = Complete;
3162
3163 // After this node is complete, it contains a bunch of
3164 // raw-memory initializations. There is no need for
3165 // it to have anything to do with non-raw memory effects.
3166 // Therefore, tell all non-raw users to re-optimize themselves,
3167 // after skipping the memory effects of this initialization.
3168 PhaseIterGVN* igvn = phase->is_IterGVN();
3169 if (igvn) igvn->add_users_to_worklist(this);
3170 }
3171
3172 // convenience function
3173 // return false if the init contains any stores already
3174 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3175 InitializeNode* init = initialization();
3176 if (init == NULL || init->is_complete()) return false;
3177 init->remove_extra_zeroes();
3178 // for now, if this allocation has already collected any inits, bail:
3179 if (init->is_non_zero()) return false;
3180 init->set_complete(phase);
3181 return true;
3182 }
3183
3184 void InitializeNode::remove_extra_zeroes() {
3185 if (req() == RawStores) return;
3186 Node* zmem = zero_memory();
3187 uint fill = RawStores;
3188 for (uint i = fill; i < req(); i++) {
3189 Node* n = in(i);
3190 if (n->is_top() || n == zmem) continue; // skip
3191 if (fill < i) set_req(fill, n); // compact
3192 ++fill;
3193 }
3194 // delete any empty spaces created:
3195 while (fill < req()) {
3196 del_req(fill);
3197 }
3198 }
3199
3200 // Helper for remembering which stores go with which offsets.
3201 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3202 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3203 intptr_t offset = -1;
3204 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3205 phase, offset);
3206 if (base == NULL) return -1; // something is dead,
3207 if (offset < 0) return -1; // dead, dead
3208 return offset;
3209 }
3210
3211 // Helper for proving that an initialization expression is
3212 // "simple enough" to be folded into an object initialization.
3213 // Attempts to prove that a store's initial value 'n' can be captured
3214 // within the initialization without creating a vicious cycle, such as:
3215 // { Foo p = new Foo(); p.next = p; }
3216 // True for constants and parameters and small combinations thereof.
3217 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3218 if (n == NULL) return true; // (can this really happen?)
3219 if (n->is_Proj()) n = n->in(0);
3220 if (n == this) return false; // found a cycle
3221 if (n->is_Con()) return true;
3222 if (n->is_Start()) return true; // params, etc., are OK
3223 if (n->is_Root()) return true; // even better
3224
3225 Node* ctl = n->in(0);
3226 if (ctl != NULL && !ctl->is_top()) {
3227 if (ctl->is_Proj()) ctl = ctl->in(0);
3228 if (ctl == this) return false;
3229
3230 // If we already know that the enclosing memory op is pinned right after
3231 // the init, then any control flow that the store has picked up
3232 // must have preceded the init, or else be equal to the init.
3233 // Even after loop optimizations (which might change control edges)
3234 // a store is never pinned *before* the availability of its inputs.
3235 if (!MemNode::all_controls_dominate(n, this))
3236 return false; // failed to prove a good control
3237 }
3238
3239 // Check data edges for possible dependencies on 'this'.
3240 if ((count += 1) > 20) return false; // complexity limit
3241 for (uint i = 1; i < n->req(); i++) {
3242 Node* m = n->in(i);
3243 if (m == NULL || m == n || m->is_top()) continue;
3244 uint first_i = n->find_edge(m);
3245 if (i != first_i) continue; // process duplicate edge just once
3246 if (!detect_init_independence(m, count)) {
3247 return false;
3248 }
3249 }
3250
3251 return true;
3252 }
3253
3254 // Here are all the checks a Store must pass before it can be moved into
3255 // an initialization. Returns zero if a check fails.
3256 // On success, returns the (constant) offset to which the store applies,
3257 // within the initialized memory.
3258 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3259 const int FAIL = 0;
3260 if (st->is_unaligned_access()) {
3261 return FAIL;
3262 }
3263 if (st->req() != MemNode::ValueIn + 1)
3264 return FAIL; // an inscrutable StoreNode (card mark?)
3265 Node* ctl = st->in(MemNode::Control);
3266 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3267 return FAIL; // must be unconditional after the initialization
3268 Node* mem = st->in(MemNode::Memory);
3269 if (!(mem->is_Proj() && mem->in(0) == this))
3270 return FAIL; // must not be preceded by other stores
3271 Node* adr = st->in(MemNode::Address);
3272 intptr_t offset;
3273 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3274 if (alloc == NULL)
3275 return FAIL; // inscrutable address
3276 if (alloc != allocation())
3277 return FAIL; // wrong allocation! (store needs to float up)
3278 Node* val = st->in(MemNode::ValueIn);
3279 int complexity_count = 0;
3280 if (!detect_init_independence(val, complexity_count))
3281 return FAIL; // stored value must be 'simple enough'
3282
3283 // The Store can be captured only if nothing after the allocation
3284 // and before the Store is using the memory location that the store
3285 // overwrites.
3286 bool failed = false;
3287 // If is_complete_with_arraycopy() is true the shape of the graph is
3288 // well defined and is safe so no need for extra checks.
3289 if (!is_complete_with_arraycopy()) {
3290 // We are going to look at each use of the memory state following
3291 // the allocation to make sure nothing reads the memory that the
3292 // Store writes.
3293 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3294 int alias_idx = phase->C->get_alias_index(t_adr);
3295 ResourceMark rm;
3296 Unique_Node_List mems;
3297 mems.push(mem);
3298 Node* unique_merge = NULL;
3299 for (uint next = 0; next < mems.size(); ++next) {
3300 Node *m = mems.at(next);
3301 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3302 Node *n = m->fast_out(j);
3303 if (n->outcnt() == 0) {
3304 continue;
3305 }
3306 if (n == st) {
3307 continue;
3308 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3309 // If the control of this use is different from the control
3310 // of the Store which is right after the InitializeNode then
3311 // this node cannot be between the InitializeNode and the
3312 // Store.
3313 continue;
3314 } else if (n->is_MergeMem()) {
3315 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3316 // We can hit a MergeMemNode (that will likely go away
3317 // later) that is a direct use of the memory state
3318 // following the InitializeNode on the same slice as the
3319 // store node that we'd like to capture. We need to check
3320 // the uses of the MergeMemNode.
3321 mems.push(n);
3322 }
3323 } else if (n->is_Mem()) {
3324 Node* other_adr = n->in(MemNode::Address);
3325 if (other_adr == adr) {
3326 failed = true;
3327 break;
3328 } else {
3329 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3330 if (other_t_adr != NULL) {
3331 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3332 if (other_alias_idx == alias_idx) {
3333 // A load from the same memory slice as the store right
3334 // after the InitializeNode. We check the control of the
3335 // object/array that is loaded from. If it's the same as
3336 // the store control then we cannot capture the store.
3337 assert(!n->is_Store(), "2 stores to same slice on same control?");
3338 Node* base = other_adr;
3339 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3340 base = base->in(AddPNode::Base);
3341 if (base != NULL) {
3342 base = base->uncast();
3343 if (base->is_Proj() && base->in(0) == alloc) {
3344 failed = true;
3345 break;
3346 }
3347 }
3348 }
3349 }
3350 }
3351 } else {
3352 failed = true;
3353 break;
3354 }
3355 }
3356 }
3357 }
3358 if (failed) {
3359 if (!can_reshape) {
3360 // We decided we couldn't capture the store during parsing. We
3361 // should try again during the next IGVN once the graph is
3362 // cleaner.
3363 phase->C->record_for_igvn(st);
3364 }
3365 return FAIL;
3366 }
3367
3368 return offset; // success
3369 }
3370
3371 // Find the captured store in(i) which corresponds to the range
3372 // [start..start+size) in the initialized object.
3373 // If there is one, return its index i. If there isn't, return the
3374 // negative of the index where it should be inserted.
3375 // Return 0 if the queried range overlaps an initialization boundary
3376 // or if dead code is encountered.
3377 // If size_in_bytes is zero, do not bother with overlap checks.
3378 int InitializeNode::captured_store_insertion_point(intptr_t start,
3379 int size_in_bytes,
3380 PhaseTransform* phase) {
3381 const int FAIL = 0, MAX_STORE = BytesPerLong;
3382
3383 if (is_complete())
3384 return FAIL; // arraycopy got here first; punt
3385
3386 assert(allocation() != NULL, "must be present");
3387
3388 // no negatives, no header fields:
3389 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3390
3391 // after a certain size, we bail out on tracking all the stores:
3392 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3393 if (start >= ti_limit) return FAIL;
3394
3395 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3396 if (i >= limit) return -(int)i; // not found; here is where to put it
3397
3398 Node* st = in(i);
3399 intptr_t st_off = get_store_offset(st, phase);
3400 if (st_off < 0) {
3401 if (st != zero_memory()) {
3402 return FAIL; // bail out if there is dead garbage
3403 }
3404 } else if (st_off > start) {
3405 // ...we are done, since stores are ordered
3406 if (st_off < start + size_in_bytes) {
3407 return FAIL; // the next store overlaps
3408 }
3409 return -(int)i; // not found; here is where to put it
3410 } else if (st_off < start) {
3411 if (size_in_bytes != 0 &&
3412 start < st_off + MAX_STORE &&
3413 start < st_off + st->as_Store()->memory_size()) {
3414 return FAIL; // the previous store overlaps
3415 }
3416 } else {
3417 if (size_in_bytes != 0 &&
3418 st->as_Store()->memory_size() != size_in_bytes) {
3419 return FAIL; // mismatched store size
3420 }
3421 return i;
3422 }
3423
3424 ++i;
3425 }
3426 }
3427
3428 // Look for a captured store which initializes at the offset 'start'
3429 // with the given size. If there is no such store, and no other
3430 // initialization interferes, then return zero_memory (the memory
3431 // projection of the AllocateNode).
3432 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3433 PhaseTransform* phase) {
3434 assert(stores_are_sane(phase), "");
3435 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3436 if (i == 0) {
3437 return NULL; // something is dead
3438 } else if (i < 0) {
3439 return zero_memory(); // just primordial zero bits here
3440 } else {
3441 Node* st = in(i); // here is the store at this position
3442 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3443 return st;
3444 }
3445 }
3446
3447 // Create, as a raw pointer, an address within my new object at 'offset'.
3448 Node* InitializeNode::make_raw_address(intptr_t offset,
3449 PhaseTransform* phase) {
3450 Node* addr = in(RawAddress);
3451 if (offset != 0) {
3452 Compile* C = phase->C;
3453 addr = phase->transform( new AddPNode(C->top(), addr,
3454 phase->MakeConX(offset)) );
3455 }
3456 return addr;
3457 }
3458
3459 // Clone the given store, converting it into a raw store
3460 // initializing a field or element of my new object.
3461 // Caller is responsible for retiring the original store,
3462 // with subsume_node or the like.
3463 //
3464 // From the example above InitializeNode::InitializeNode,
3465 // here are the old stores to be captured:
3466 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3467 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3468 //
3469 // Here is the changed code; note the extra edges on init:
3470 // alloc = (Allocate ...)
3471 // rawoop = alloc.RawAddress
3472 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3473 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3474 // init = (Initialize alloc.Control alloc.Memory rawoop
3475 // rawstore1 rawstore2)
3476 //
3477 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3478 PhaseTransform* phase, bool can_reshape) {
3479 assert(stores_are_sane(phase), "");
3480
3481 if (start < 0) return NULL;
3482 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3483
3484 Compile* C = phase->C;
3485 int size_in_bytes = st->memory_size();
3486 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3487 if (i == 0) return NULL; // bail out
3488 Node* prev_mem = NULL; // raw memory for the captured store
3489 if (i > 0) {
3490 prev_mem = in(i); // there is a pre-existing store under this one
3491 set_req(i, C->top()); // temporarily disconnect it
3492 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3493 } else {
3494 i = -i; // no pre-existing store
3495 prev_mem = zero_memory(); // a slice of the newly allocated object
3496 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3497 set_req(--i, C->top()); // reuse this edge; it has been folded away
3498 else
3499 ins_req(i, C->top()); // build a new edge
3500 }
3501 Node* new_st = st->clone();
3502 new_st->set_req(MemNode::Control, in(Control));
3503 new_st->set_req(MemNode::Memory, prev_mem);
3504 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3505 new_st = phase->transform(new_st);
3506
3507 // At this point, new_st might have swallowed a pre-existing store
3508 // at the same offset, or perhaps new_st might have disappeared,
3509 // if it redundantly stored the same value (or zero to fresh memory).
3510
3511 // In any case, wire it in:
3512 phase->igvn_rehash_node_delayed(this);
3513 set_req(i, new_st);
3514
3515 // The caller may now kill the old guy.
3516 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3517 assert(check_st == new_st || check_st == NULL, "must be findable");
3518 assert(!is_complete(), "");
3519 return new_st;
3520 }
3521
3522 static bool store_constant(jlong* tiles, int num_tiles,
3523 intptr_t st_off, int st_size,
3524 jlong con) {
3525 if ((st_off & (st_size-1)) != 0)
3526 return false; // strange store offset (assume size==2**N)
3527 address addr = (address)tiles + st_off;
3528 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3529 switch (st_size) {
3530 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3531 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3532 case sizeof(jint): *(jint*) addr = (jint) con; break;
3533 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3534 default: return false; // strange store size (detect size!=2**N here)
3535 }
3536 return true; // return success to caller
3537 }
3538
3539 // Coalesce subword constants into int constants and possibly
3540 // into long constants. The goal, if the CPU permits,
3541 // is to initialize the object with a small number of 64-bit tiles.
3542 // Also, convert floating-point constants to bit patterns.
3543 // Non-constants are not relevant to this pass.
3544 //
3545 // In terms of the running example on InitializeNode::InitializeNode
3546 // and InitializeNode::capture_store, here is the transformation
3547 // of rawstore1 and rawstore2 into rawstore12:
3548 // alloc = (Allocate ...)
3549 // rawoop = alloc.RawAddress
3550 // tile12 = 0x00010002
3551 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3552 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3553 //
3554 void
3555 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3556 Node* size_in_bytes,
3557 PhaseGVN* phase) {
3558 Compile* C = phase->C;
3559
3560 assert(stores_are_sane(phase), "");
3561 // Note: After this pass, they are not completely sane,
3562 // since there may be some overlaps.
3563
3564 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3565
3566 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3567 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3568 size_limit = MIN2(size_limit, ti_limit);
3569 size_limit = align_up(size_limit, BytesPerLong);
3570 int num_tiles = size_limit / BytesPerLong;
3571
3572 // allocate space for the tile map:
3573 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3574 jlong tiles_buf[small_len];
3575 Node* nodes_buf[small_len];
3576 jlong inits_buf[small_len];
3577 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3578 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3579 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3580 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3581 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3582 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3583 // tiles: exact bitwise model of all primitive constants
3584 // nodes: last constant-storing node subsumed into the tiles model
3585 // inits: which bytes (in each tile) are touched by any initializations
3586
3587 //// Pass A: Fill in the tile model with any relevant stores.
3588
3589 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3590 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3591 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3592 Node* zmem = zero_memory(); // initially zero memory state
3593 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3594 Node* st = in(i);
3595 intptr_t st_off = get_store_offset(st, phase);
3596
3597 // Figure out the store's offset and constant value:
3598 if (st_off < header_size) continue; //skip (ignore header)
3599 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3600 int st_size = st->as_Store()->memory_size();
3601 if (st_off + st_size > size_limit) break;
3602
3603 // Record which bytes are touched, whether by constant or not.
3604 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3605 continue; // skip (strange store size)
3606
3607 const Type* val = phase->type(st->in(MemNode::ValueIn));
3608 if (!val->singleton()) continue; //skip (non-con store)
3609 BasicType type = val->basic_type();
3610
3611 jlong con = 0;
3612 switch (type) {
3613 case T_INT: con = val->is_int()->get_con(); break;
3614 case T_LONG: con = val->is_long()->get_con(); break;
3615 case T_FLOAT: con = jint_cast(val->getf()); break;
3616 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3617 default: continue; //skip (odd store type)
3618 }
3619
3620 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3621 st->Opcode() == Op_StoreL) {
3622 continue; // This StoreL is already optimal.
3623 }
3624
3625 // Store down the constant.
3626 store_constant(tiles, num_tiles, st_off, st_size, con);
3627
3628 intptr_t j = st_off >> LogBytesPerLong;
3629
3630 if (type == T_INT && st_size == BytesPerInt
3631 && (st_off & BytesPerInt) == BytesPerInt) {
3632 jlong lcon = tiles[j];
3633 if (!Matcher::isSimpleConstant64(lcon) &&
3634 st->Opcode() == Op_StoreI) {
3635 // This StoreI is already optimal by itself.
3636 jint* intcon = (jint*) &tiles[j];
3637 intcon[1] = 0; // undo the store_constant()
3638
3639 // If the previous store is also optimal by itself, back up and
3640 // undo the action of the previous loop iteration... if we can.
3641 // But if we can't, just let the previous half take care of itself.
3642 st = nodes[j];
3643 st_off -= BytesPerInt;
3644 con = intcon[0];
3645 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3646 assert(st_off >= header_size, "still ignoring header");
3647 assert(get_store_offset(st, phase) == st_off, "must be");
3648 assert(in(i-1) == zmem, "must be");
3649 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3650 assert(con == tcon->is_int()->get_con(), "must be");
3651 // Undo the effects of the previous loop trip, which swallowed st:
3652 intcon[0] = 0; // undo store_constant()
3653 set_req(i-1, st); // undo set_req(i, zmem)
3654 nodes[j] = NULL; // undo nodes[j] = st
3655 --old_subword; // undo ++old_subword
3656 }
3657 continue; // This StoreI is already optimal.
3658 }
3659 }
3660
3661 // This store is not needed.
3662 set_req(i, zmem);
3663 nodes[j] = st; // record for the moment
3664 if (st_size < BytesPerLong) // something has changed
3665 ++old_subword; // includes int/float, but who's counting...
3666 else ++old_long;
3667 }
3668
3669 if ((old_subword + old_long) == 0)
3670 return; // nothing more to do
3671
3672 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3673 // Be sure to insert them before overlapping non-constant stores.
3674 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3675 for (int j = 0; j < num_tiles; j++) {
3676 jlong con = tiles[j];
3677 jlong init = inits[j];
3678 if (con == 0) continue;
3679 jint con0, con1; // split the constant, address-wise
3680 jint init0, init1; // split the init map, address-wise
3681 { union { jlong con; jint intcon[2]; } u;
3682 u.con = con;
3683 con0 = u.intcon[0];
3684 con1 = u.intcon[1];
3685 u.con = init;
3686 init0 = u.intcon[0];
3687 init1 = u.intcon[1];
3688 }
3689
3690 Node* old = nodes[j];
3691 assert(old != NULL, "need the prior store");
3692 intptr_t offset = (j * BytesPerLong);
3693
3694 bool split = !Matcher::isSimpleConstant64(con);
3695
3696 if (offset < header_size) {
3697 assert(offset + BytesPerInt >= header_size, "second int counts");
3698 assert(*(jint*)&tiles[j] == 0, "junk in header");
3699 split = true; // only the second word counts
3700 // Example: int a[] = { 42 ... }
3701 } else if (con0 == 0 && init0 == -1) {
3702 split = true; // first word is covered by full inits
3703 // Example: int a[] = { ... foo(), 42 ... }
3704 } else if (con1 == 0 && init1 == -1) {
3705 split = true; // second word is covered by full inits
3706 // Example: int a[] = { ... 42, foo() ... }
3707 }
3708
3709 // Here's a case where init0 is neither 0 nor -1:
3710 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3711 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3712 // In this case the tile is not split; it is (jlong)42.
3713 // The big tile is stored down, and then the foo() value is inserted.
3714 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3715
3716 Node* ctl = old->in(MemNode::Control);
3717 Node* adr = make_raw_address(offset, phase);
3718 const TypePtr* atp = TypeRawPtr::BOTTOM;
3719
3720 // One or two coalesced stores to plop down.
3721 Node* st[2];
3722 intptr_t off[2];
3723 int nst = 0;
3724 if (!split) {
3725 ++new_long;
3726 off[nst] = offset;
3727 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3728 phase->longcon(con), T_LONG, MemNode::unordered);
3729 } else {
3730 // Omit either if it is a zero.
3731 if (con0 != 0) {
3732 ++new_int;
3733 off[nst] = offset;
3734 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3735 phase->intcon(con0), T_INT, MemNode::unordered);
3736 }
3737 if (con1 != 0) {
3738 ++new_int;
3739 offset += BytesPerInt;
3740 adr = make_raw_address(offset, phase);
3741 off[nst] = offset;
3742 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3743 phase->intcon(con1), T_INT, MemNode::unordered);
3744 }
3745 }
3746
3747 // Insert second store first, then the first before the second.
3748 // Insert each one just before any overlapping non-constant stores.
3749 while (nst > 0) {
3750 Node* st1 = st[--nst];
3751 C->copy_node_notes_to(st1, old);
3752 st1 = phase->transform(st1);
3753 offset = off[nst];
3754 assert(offset >= header_size, "do not smash header");
3755 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3756 guarantee(ins_idx != 0, "must re-insert constant store");
3757 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3758 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3759 set_req(--ins_idx, st1);
3760 else
3761 ins_req(ins_idx, st1);
3762 }
3763 }
3764
3765 if (PrintCompilation && WizardMode)
3766 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3767 old_subword, old_long, new_int, new_long);
3768 if (C->log() != NULL)
3769 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3770 old_subword, old_long, new_int, new_long);
3771
3772 // Clean up any remaining occurrences of zmem:
3773 remove_extra_zeroes();
3774 }
3775
3776 // Explore forward from in(start) to find the first fully initialized
3777 // word, and return its offset. Skip groups of subword stores which
3778 // together initialize full words. If in(start) is itself part of a
3779 // fully initialized word, return the offset of in(start). If there
3780 // are no following full-word stores, or if something is fishy, return
3781 // a negative value.
3782 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3783 int int_map = 0;
3784 intptr_t int_map_off = 0;
3785 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3786
3787 for (uint i = start, limit = req(); i < limit; i++) {
3788 Node* st = in(i);
3789
3790 intptr_t st_off = get_store_offset(st, phase);
3791 if (st_off < 0) break; // return conservative answer
3792
3793 int st_size = st->as_Store()->memory_size();
3794 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3795 return st_off; // we found a complete word init
3796 }
3797
3798 // update the map:
3799
3800 intptr_t this_int_off = align_down(st_off, BytesPerInt);
3801 if (this_int_off != int_map_off) {
3802 // reset the map:
3803 int_map = 0;
3804 int_map_off = this_int_off;
3805 }
3806
3807 int subword_off = st_off - this_int_off;
3808 int_map |= right_n_bits(st_size) << subword_off;
3809 if ((int_map & FULL_MAP) == FULL_MAP) {
3810 return this_int_off; // we found a complete word init
3811 }
3812
3813 // Did this store hit or cross the word boundary?
3814 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
3815 if (next_int_off == this_int_off + BytesPerInt) {
3816 // We passed the current int, without fully initializing it.
3817 int_map_off = next_int_off;
3818 int_map >>= BytesPerInt;
3819 } else if (next_int_off > this_int_off + BytesPerInt) {
3820 // We passed the current and next int.
3821 return this_int_off + BytesPerInt;
3822 }
3823 }
3824
3825 return -1;
3826 }
3827
3828
3829 // Called when the associated AllocateNode is expanded into CFG.
3830 // At this point, we may perform additional optimizations.
3831 // Linearize the stores by ascending offset, to make memory
3832 // activity as coherent as possible.
3833 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3834 intptr_t header_size,
3835 Node* size_in_bytes,
3836 PhaseGVN* phase) {
3837 assert(!is_complete(), "not already complete");
3838 assert(stores_are_sane(phase), "");
3839 assert(allocation() != NULL, "must be present");
3840
3841 remove_extra_zeroes();
3842
3843 if (ReduceFieldZeroing || ReduceBulkZeroing)
3844 // reduce instruction count for common initialization patterns
3845 coalesce_subword_stores(header_size, size_in_bytes, phase);
3846
3847 Node* zmem = zero_memory(); // initially zero memory state
3848 Node* inits = zmem; // accumulating a linearized chain of inits
3849 #ifdef ASSERT
3850 intptr_t first_offset = allocation()->minimum_header_size();
3851 intptr_t last_init_off = first_offset; // previous init offset
3852 intptr_t last_init_end = first_offset; // previous init offset+size
3853 intptr_t last_tile_end = first_offset; // previous tile offset+size
3854 #endif
3855 intptr_t zeroes_done = header_size;
3856
3857 bool do_zeroing = true; // we might give up if inits are very sparse
3858 int big_init_gaps = 0; // how many large gaps have we seen?
3859
3860 if (UseTLAB && ZeroTLAB) do_zeroing = false;
3861 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3862
3863 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3864 Node* st = in(i);
3865 intptr_t st_off = get_store_offset(st, phase);
3866 if (st_off < 0)
3867 break; // unknown junk in the inits
3868 if (st->in(MemNode::Memory) != zmem)
3869 break; // complicated store chains somehow in list
3870
3871 int st_size = st->as_Store()->memory_size();
3872 intptr_t next_init_off = st_off + st_size;
3873
3874 if (do_zeroing && zeroes_done < next_init_off) {
3875 // See if this store needs a zero before it or under it.
3876 intptr_t zeroes_needed = st_off;
3877
3878 if (st_size < BytesPerInt) {
3879 // Look for subword stores which only partially initialize words.
3880 // If we find some, we must lay down some word-level zeroes first,
3881 // underneath the subword stores.
3882 //
3883 // Examples:
3884 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3885 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3886 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3887 //
3888 // Note: coalesce_subword_stores may have already done this,
3889 // if it was prompted by constant non-zero subword initializers.
3890 // But this case can still arise with non-constant stores.
3891
3892 intptr_t next_full_store = find_next_fullword_store(i, phase);
3893
3894 // In the examples above:
3895 // in(i) p q r s x y z
3896 // st_off 12 13 14 15 12 13 14
3897 // st_size 1 1 1 1 1 1 1
3898 // next_full_s. 12 16 16 16 16 16 16
3899 // z's_done 12 16 16 16 12 16 12
3900 // z's_needed 12 16 16 16 16 16 16
3901 // zsize 0 0 0 0 4 0 4
3902 if (next_full_store < 0) {
3903 // Conservative tack: Zero to end of current word.
3904 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
3905 } else {
3906 // Zero to beginning of next fully initialized word.
3907 // Or, don't zero at all, if we are already in that word.
3908 assert(next_full_store >= zeroes_needed, "must go forward");
3909 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3910 zeroes_needed = next_full_store;
3911 }
3912 }
3913
3914 if (zeroes_needed > zeroes_done) {
3915 intptr_t zsize = zeroes_needed - zeroes_done;
3916 // Do some incremental zeroing on rawmem, in parallel with inits.
3917 zeroes_done = align_down(zeroes_done, BytesPerInt);
3918 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3919 zeroes_done, zeroes_needed,
3920 phase);
3921 zeroes_done = zeroes_needed;
3922 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
3923 do_zeroing = false; // leave the hole, next time
3924 }
3925 }
3926
3927 // Collect the store and move on:
3928 st->set_req(MemNode::Memory, inits);
3929 inits = st; // put it on the linearized chain
3930 set_req(i, zmem); // unhook from previous position
3931
3932 if (zeroes_done == st_off)
3933 zeroes_done = next_init_off;
3934
3935 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3936
3937 #ifdef ASSERT
3938 // Various order invariants. Weaker than stores_are_sane because
3939 // a large constant tile can be filled in by smaller non-constant stores.
3940 assert(st_off >= last_init_off, "inits do not reverse");
3941 last_init_off = st_off;
3942 const Type* val = NULL;
3943 if (st_size >= BytesPerInt &&
3944 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3945 (int)val->basic_type() < (int)T_OBJECT) {
3946 assert(st_off >= last_tile_end, "tiles do not overlap");
3947 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3948 last_tile_end = MAX2(last_tile_end, next_init_off);
3949 } else {
3950 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
3951 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3952 assert(st_off >= last_init_end, "inits do not overlap");
3953 last_init_end = next_init_off; // it's a non-tile
3954 }
3955 #endif //ASSERT
3956 }
3957
3958 remove_extra_zeroes(); // clear out all the zmems left over
3959 add_req(inits);
3960
3961 if (!(UseTLAB && ZeroTLAB)) {
3962 // If anything remains to be zeroed, zero it all now.
3963 zeroes_done = align_down(zeroes_done, BytesPerInt);
3964 // if it is the last unused 4 bytes of an instance, forget about it
3965 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3966 if (zeroes_done + BytesPerLong >= size_limit) {
3967 AllocateNode* alloc = allocation();
3968 assert(alloc != NULL, "must be present");
3969 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
3970 Node* klass_node = alloc->in(AllocateNode::KlassNode);
3971 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3972 if (zeroes_done == k->layout_helper())
3973 zeroes_done = size_limit;
3974 }
3975 }
3976 if (zeroes_done < size_limit) {
3977 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3978 zeroes_done, size_in_bytes, phase);
3979 }
3980 }
3981
3982 set_complete(phase);
3983 return rawmem;
3984 }
3985
3986
3987 #ifdef ASSERT
3988 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3989 if (is_complete())
3990 return true; // stores could be anything at this point
3991 assert(allocation() != NULL, "must be present");
3992 intptr_t last_off = allocation()->minimum_header_size();
3993 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3994 Node* st = in(i);
3995 intptr_t st_off = get_store_offset(st, phase);
3996 if (st_off < 0) continue; // ignore dead garbage
3997 if (last_off > st_off) {
3998 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3999 this->dump(2);
4000 assert(false, "ascending store offsets");
4001 return false;
4002 }
4003 last_off = st_off + st->as_Store()->memory_size();
4004 }
4005 return true;
4006 }
4007 #endif //ASSERT
4008
4009
4010
4011
4012 //============================MergeMemNode=====================================
4013 //
4014 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4015 // contributing store or call operations. Each contributor provides the memory
4016 // state for a particular "alias type" (see Compile::alias_type). For example,
4017 // if a MergeMem has an input X for alias category #6, then any memory reference
4018 // to alias category #6 may use X as its memory state input, as an exact equivalent
4019 // to using the MergeMem as a whole.
4020 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4021 //
4022 // (Here, the <N> notation gives the index of the relevant adr_type.)
4023 //
4024 // In one special case (and more cases in the future), alias categories overlap.
4025 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4026 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4027 // it is exactly equivalent to that state W:
4028 // MergeMem(<Bot>: W) <==> W
4029 //
4030 // Usually, the merge has more than one input. In that case, where inputs
4031 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4032 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4033 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4034 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4035 //
4036 // A merge can take a "wide" memory state as one of its narrow inputs.
4037 // This simply means that the merge observes out only the relevant parts of
4038 // the wide input. That is, wide memory states arriving at narrow merge inputs
4039 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4040 //
4041 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4042 // and that memory slices "leak through":
4043 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4044 //
4045 // But, in such a cascade, repeated memory slices can "block the leak":
4046 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4047 //
4048 // In the last example, Y is not part of the combined memory state of the
4049 // outermost MergeMem. The system must, of course, prevent unschedulable
4050 // memory states from arising, so you can be sure that the state Y is somehow
4051 // a precursor to state Y'.
4052 //
4053 //
4054 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4055 // of each MergeMemNode array are exactly the numerical alias indexes, including
4056 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4057 // Compile::alias_type (and kin) produce and manage these indexes.
4058 //
4059 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4060 // (Note that this provides quick access to the top node inside MergeMem methods,
4061 // without the need to reach out via TLS to Compile::current.)
4062 //
4063 // As a consequence of what was just described, a MergeMem that represents a full
4064 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4065 // containing all alias categories.
4066 //
4067 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4068 //
4069 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4070 // a memory state for the alias type <N>, or else the top node, meaning that
4071 // there is no particular input for that alias type. Note that the length of
4072 // a MergeMem is variable, and may be extended at any time to accommodate new
4073 // memory states at larger alias indexes. When merges grow, they are of course
4074 // filled with "top" in the unused in() positions.
4075 //
4076 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4077 // (Top was chosen because it works smoothly with passes like GCM.)
4078 //
4079 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4080 // the type of random VM bits like TLS references.) Since it is always the
4081 // first non-Bot memory slice, some low-level loops use it to initialize an
4082 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4083 //
4084 //
4085 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4086 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4087 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4088 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4089 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4090 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4091 //
4092 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4093 // really that different from the other memory inputs. An abbreviation called
4094 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4095 //
4096 //
4097 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4098 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4099 // that "emerges though" the base memory will be marked as excluding the alias types
4100 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4101 //
4102 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4103 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4104 //
4105 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4106 // (It is currently unimplemented.) As you can see, the resulting merge is
4107 // actually a disjoint union of memory states, rather than an overlay.
4108 //
4109
4110 //------------------------------MergeMemNode-----------------------------------
4111 Node* MergeMemNode::make_empty_memory() {
4112 Node* empty_memory = (Node*) Compile::current()->top();
4113 assert(empty_memory->is_top(), "correct sentinel identity");
4114 return empty_memory;
4115 }
4116
4117 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4118 init_class_id(Class_MergeMem);
4119 // all inputs are nullified in Node::Node(int)
4120 // set_input(0, NULL); // no control input
4121
4122 // Initialize the edges uniformly to top, for starters.
4123 Node* empty_mem = make_empty_memory();
4124 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4125 init_req(i,empty_mem);
4126 }
4127 assert(empty_memory() == empty_mem, "");
4128
4129 if( new_base != NULL && new_base->is_MergeMem() ) {
4130 MergeMemNode* mdef = new_base->as_MergeMem();
4131 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4132 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4133 mms.set_memory(mms.memory2());
4134 }
4135 assert(base_memory() == mdef->base_memory(), "");
4136 } else {
4137 set_base_memory(new_base);
4138 }
4139 }
4140
4141 // Make a new, untransformed MergeMem with the same base as 'mem'.
4142 // If mem is itself a MergeMem, populate the result with the same edges.
4143 MergeMemNode* MergeMemNode::make(Node* mem) {
4144 return new MergeMemNode(mem);
4145 }
4146
4147 //------------------------------cmp--------------------------------------------
4148 uint MergeMemNode::hash() const { return NO_HASH; }
4149 uint MergeMemNode::cmp( const Node &n ) const {
4150 return (&n == this); // Always fail except on self
4151 }
4152
4153 //------------------------------Identity---------------------------------------
4154 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4155 // Identity if this merge point does not record any interesting memory
4156 // disambiguations.
4157 Node* base_mem = base_memory();
4158 Node* empty_mem = empty_memory();
4159 if (base_mem != empty_mem) { // Memory path is not dead?
4160 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4161 Node* mem = in(i);
4162 if (mem != empty_mem && mem != base_mem) {
4163 return this; // Many memory splits; no change
4164 }
4165 }
4166 }
4167 return base_mem; // No memory splits; ID on the one true input
4168 }
4169
4170 //------------------------------Ideal------------------------------------------
4171 // This method is invoked recursively on chains of MergeMem nodes
4172 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4173 // Remove chain'd MergeMems
4174 //
4175 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4176 // relative to the "in(Bot)". Since we are patching both at the same time,
4177 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4178 // but rewrite each "in(i)" relative to the new "in(Bot)".
4179 Node *progress = NULL;
4180
4181
4182 Node* old_base = base_memory();
4183 Node* empty_mem = empty_memory();
4184 if (old_base == empty_mem)
4185 return NULL; // Dead memory path.
4186
4187 MergeMemNode* old_mbase;
4188 if (old_base != NULL && old_base->is_MergeMem())
4189 old_mbase = old_base->as_MergeMem();
4190 else
4191 old_mbase = NULL;
4192 Node* new_base = old_base;
4193
4194 // simplify stacked MergeMems in base memory
4195 if (old_mbase) new_base = old_mbase->base_memory();
4196
4197 // the base memory might contribute new slices beyond my req()
4198 if (old_mbase) grow_to_match(old_mbase);
4199
4200 // Look carefully at the base node if it is a phi.
4201 PhiNode* phi_base;
4202 if (new_base != NULL && new_base->is_Phi())
4203 phi_base = new_base->as_Phi();
4204 else
4205 phi_base = NULL;
4206
4207 Node* phi_reg = NULL;
4208 uint phi_len = (uint)-1;
4209 if (phi_base != NULL && !phi_base->is_copy()) {
4210 // do not examine phi if degraded to a copy
4211 phi_reg = phi_base->region();
4212 phi_len = phi_base->req();
4213 // see if the phi is unfinished
4214 for (uint i = 1; i < phi_len; i++) {
4215 if (phi_base->in(i) == NULL) {
4216 // incomplete phi; do not look at it yet!
4217 phi_reg = NULL;
4218 phi_len = (uint)-1;
4219 break;
4220 }
4221 }
4222 }
4223
4224 // Note: We do not call verify_sparse on entry, because inputs
4225 // can normalize to the base_memory via subsume_node or similar
4226 // mechanisms. This method repairs that damage.
4227
4228 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4229
4230 // Look at each slice.
4231 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4232 Node* old_in = in(i);
4233 // calculate the old memory value
4234 Node* old_mem = old_in;
4235 if (old_mem == empty_mem) old_mem = old_base;
4236 assert(old_mem == memory_at(i), "");
4237
4238 // maybe update (reslice) the old memory value
4239
4240 // simplify stacked MergeMems
4241 Node* new_mem = old_mem;
4242 MergeMemNode* old_mmem;
4243 if (old_mem != NULL && old_mem->is_MergeMem())
4244 old_mmem = old_mem->as_MergeMem();
4245 else
4246 old_mmem = NULL;
4247 if (old_mmem == this) {
4248 // This can happen if loops break up and safepoints disappear.
4249 // A merge of BotPtr (default) with a RawPtr memory derived from a
4250 // safepoint can be rewritten to a merge of the same BotPtr with
4251 // the BotPtr phi coming into the loop. If that phi disappears
4252 // also, we can end up with a self-loop of the mergemem.
4253 // In general, if loops degenerate and memory effects disappear,
4254 // a mergemem can be left looking at itself. This simply means
4255 // that the mergemem's default should be used, since there is
4256 // no longer any apparent effect on this slice.
4257 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4258 // from start. Update the input to TOP.
4259 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4260 }
4261 else if (old_mmem != NULL) {
4262 new_mem = old_mmem->memory_at(i);
4263 }
4264 // else preceding memory was not a MergeMem
4265
4266 // replace equivalent phis (unfortunately, they do not GVN together)
4267 if (new_mem != NULL && new_mem != new_base &&
4268 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4269 if (new_mem->is_Phi()) {
4270 PhiNode* phi_mem = new_mem->as_Phi();
4271 for (uint i = 1; i < phi_len; i++) {
4272 if (phi_base->in(i) != phi_mem->in(i)) {
4273 phi_mem = NULL;
4274 break;
4275 }
4276 }
4277 if (phi_mem != NULL) {
4278 // equivalent phi nodes; revert to the def
4279 new_mem = new_base;
4280 }
4281 }
4282 }
4283
4284 // maybe store down a new value
4285 Node* new_in = new_mem;
4286 if (new_in == new_base) new_in = empty_mem;
4287
4288 if (new_in != old_in) {
4289 // Warning: Do not combine this "if" with the previous "if"
4290 // A memory slice might have be be rewritten even if it is semantically
4291 // unchanged, if the base_memory value has changed.
4292 set_req(i, new_in);
4293 progress = this; // Report progress
4294 }
4295 }
4296
4297 if (new_base != old_base) {
4298 set_req(Compile::AliasIdxBot, new_base);
4299 // Don't use set_base_memory(new_base), because we need to update du.
4300 assert(base_memory() == new_base, "");
4301 progress = this;
4302 }
4303
4304 if( base_memory() == this ) {
4305 // a self cycle indicates this memory path is dead
4306 set_req(Compile::AliasIdxBot, empty_mem);
4307 }
4308
4309 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4310 // Recursion must occur after the self cycle check above
4311 if( base_memory()->is_MergeMem() ) {
4312 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4313 Node *m = phase->transform(new_mbase); // Rollup any cycles
4314 if( m != NULL &&
4315 (m->is_top() ||
4316 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4317 // propagate rollup of dead cycle to self
4318 set_req(Compile::AliasIdxBot, empty_mem);
4319 }
4320 }
4321
4322 if( base_memory() == empty_mem ) {
4323 progress = this;
4324 // Cut inputs during Parse phase only.
4325 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4326 if( !can_reshape ) {
4327 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4328 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4329 }
4330 }
4331 }
4332
4333 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4334 // Check if PhiNode::Ideal's "Split phis through memory merges"
4335 // transform should be attempted. Look for this->phi->this cycle.
4336 uint merge_width = req();
4337 if (merge_width > Compile::AliasIdxRaw) {
4338 PhiNode* phi = base_memory()->as_Phi();
4339 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4340 if (phi->in(i) == this) {
4341 phase->is_IterGVN()->_worklist.push(phi);
4342 break;
4343 }
4344 }
4345 }
4346 }
4347
4348 assert(progress || verify_sparse(), "please, no dups of base");
4349 return progress;
4350 }
4351
4352 //-------------------------set_base_memory-------------------------------------
4353 void MergeMemNode::set_base_memory(Node *new_base) {
4354 Node* empty_mem = empty_memory();
4355 set_req(Compile::AliasIdxBot, new_base);
4356 assert(memory_at(req()) == new_base, "must set default memory");
4357 // Clear out other occurrences of new_base:
4358 if (new_base != empty_mem) {
4359 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4360 if (in(i) == new_base) set_req(i, empty_mem);
4361 }
4362 }
4363 }
4364
4365 //------------------------------out_RegMask------------------------------------
4366 const RegMask &MergeMemNode::out_RegMask() const {
4367 return RegMask::Empty;
4368 }
4369
4370 //------------------------------dump_spec--------------------------------------
4371 #ifndef PRODUCT
4372 void MergeMemNode::dump_spec(outputStream *st) const {
4373 st->print(" {");
4374 Node* base_mem = base_memory();
4375 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4376 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4377 if (mem == base_mem) { st->print(" -"); continue; }
4378 st->print( " N%d:", mem->_idx );
4379 Compile::current()->get_adr_type(i)->dump_on(st);
4380 }
4381 st->print(" }");
4382 }
4383 #endif // !PRODUCT
4384
4385
4386 #ifdef ASSERT
4387 static bool might_be_same(Node* a, Node* b) {
4388 if (a == b) return true;
4389 if (!(a->is_Phi() || b->is_Phi())) return false;
4390 // phis shift around during optimization
4391 return true; // pretty stupid...
4392 }
4393
4394 // verify a narrow slice (either incoming or outgoing)
4395 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4396 if (!VerifyAliases) return; // don't bother to verify unless requested
4397 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4398 if (Node::in_dump()) return; // muzzle asserts when printing
4399 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4400 assert(n != NULL, "");
4401 // Elide intervening MergeMem's
4402 while (n->is_MergeMem()) {
4403 n = n->as_MergeMem()->memory_at(alias_idx);
4404 }
4405 Compile* C = Compile::current();
4406 const TypePtr* n_adr_type = n->adr_type();
4407 if (n == m->empty_memory()) {
4408 // Implicit copy of base_memory()
4409 } else if (n_adr_type != TypePtr::BOTTOM) {
4410 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4411 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4412 } else {
4413 // A few places like make_runtime_call "know" that VM calls are narrow,
4414 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4415 bool expected_wide_mem = false;
4416 if (n == m->base_memory()) {
4417 expected_wide_mem = true;
4418 } else if (alias_idx == Compile::AliasIdxRaw ||
4419 n == m->memory_at(Compile::AliasIdxRaw)) {
4420 expected_wide_mem = true;
4421 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4422 // memory can "leak through" calls on channels that
4423 // are write-once. Allow this also.
4424 expected_wide_mem = true;
4425 }
4426 assert(expected_wide_mem, "expected narrow slice replacement");
4427 }
4428 }
4429 #else // !ASSERT
4430 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4431 #endif
4432
4433
4434 //-----------------------------memory_at---------------------------------------
4435 Node* MergeMemNode::memory_at(uint alias_idx) const {
4436 assert(alias_idx >= Compile::AliasIdxRaw ||
4437 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4438 "must avoid base_memory and AliasIdxTop");
4439
4440 // Otherwise, it is a narrow slice.
4441 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4442 Compile *C = Compile::current();
4443 if (is_empty_memory(n)) {
4444 // the array is sparse; empty slots are the "top" node
4445 n = base_memory();
4446 assert(Node::in_dump()
4447 || n == NULL || n->bottom_type() == Type::TOP
4448 || n->adr_type() == NULL // address is TOP
4449 || n->adr_type() == TypePtr::BOTTOM
4450 || n->adr_type() == TypeRawPtr::BOTTOM
4451 || Compile::current()->AliasLevel() == 0,
4452 "must be a wide memory");
4453 // AliasLevel == 0 if we are organizing the memory states manually.
4454 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4455 } else {
4456 // make sure the stored slice is sane
4457 #ifdef ASSERT
4458 if (VMError::is_error_reported() || Node::in_dump()) {
4459 } else if (might_be_same(n, base_memory())) {
4460 // Give it a pass: It is a mostly harmless repetition of the base.
4461 // This can arise normally from node subsumption during optimization.
4462 } else {
4463 verify_memory_slice(this, alias_idx, n);
4464 }
4465 #endif
4466 }
4467 return n;
4468 }
4469
4470 //---------------------------set_memory_at-------------------------------------
4471 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4472 verify_memory_slice(this, alias_idx, n);
4473 Node* empty_mem = empty_memory();
4474 if (n == base_memory()) n = empty_mem; // collapse default
4475 uint need_req = alias_idx+1;
4476 if (req() < need_req) {
4477 if (n == empty_mem) return; // already the default, so do not grow me
4478 // grow the sparse array
4479 do {
4480 add_req(empty_mem);
4481 } while (req() < need_req);
4482 }
4483 set_req( alias_idx, n );
4484 }
4485
4486
4487
4488 //--------------------------iteration_setup------------------------------------
4489 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4490 if (other != NULL) {
4491 grow_to_match(other);
4492 // invariant: the finite support of mm2 is within mm->req()
4493 #ifdef ASSERT
4494 for (uint i = req(); i < other->req(); i++) {
4495 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4496 }
4497 #endif
4498 }
4499 // Replace spurious copies of base_memory by top.
4500 Node* base_mem = base_memory();
4501 if (base_mem != NULL && !base_mem->is_top()) {
4502 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4503 if (in(i) == base_mem)
4504 set_req(i, empty_memory());
4505 }
4506 }
4507 }
4508
4509 //---------------------------grow_to_match-------------------------------------
4510 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4511 Node* empty_mem = empty_memory();
4512 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4513 // look for the finite support of the other memory
4514 for (uint i = other->req(); --i >= req(); ) {
4515 if (other->in(i) != empty_mem) {
4516 uint new_len = i+1;
4517 while (req() < new_len) add_req(empty_mem);
4518 break;
4519 }
4520 }
4521 }
4522
4523 //---------------------------verify_sparse-------------------------------------
4524 #ifndef PRODUCT
4525 bool MergeMemNode::verify_sparse() const {
4526 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4527 Node* base_mem = base_memory();
4528 // The following can happen in degenerate cases, since empty==top.
4529 if (is_empty_memory(base_mem)) return true;
4530 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4531 assert(in(i) != NULL, "sane slice");
4532 if (in(i) == base_mem) return false; // should have been the sentinel value!
4533 }
4534 return true;
4535 }
4536
4537 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4538 Node* n;
4539 n = mm->in(idx);
4540 if (mem == n) return true; // might be empty_memory()
4541 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4542 if (mem == n) return true;
4543 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4544 if (mem == n) return true;
4545 if (n == NULL) break;
4546 }
4547 return false;
4548 }
4549 #endif // !PRODUCT