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