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