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