1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/arraycopynode.hpp"
32 #include "opto/cfgnode.hpp"
33 #include "opto/compile.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/machnode.hpp"
38 #include "opto/matcher.hpp"
39 #include "opto/memnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/narrowptrnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regmask.hpp"
44 #include "utilities/copy.hpp"
45
46 // Portions of code courtesy of Clifford Click
47
48 // Optimization - Graph Style
49
50 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
51
52 //=============================================================================
53 uint MemNode::size_of() const { return sizeof(*this); }
54
55 const TypePtr *MemNode::adr_type() const {
56 Node* adr = in(Address);
57 if (adr == NULL) return NULL; // node is dead
58 const TypePtr* cross_check = NULL;
59 DEBUG_ONLY(cross_check = _adr_type);
60 return calculate_adr_type(adr->bottom_type(), cross_check);
61 }
62
63 #ifndef PRODUCT
64 void MemNode::dump_spec(outputStream *st) const {
65 if (in(Address) == NULL) return; // node is dead
66 #ifndef ASSERT
67 // fake the missing field
68 const TypePtr* _adr_type = NULL;
69 if (in(Address) != NULL)
70 _adr_type = in(Address)->bottom_type()->isa_ptr();
71 #endif
72 dump_adr_type(this, _adr_type, st);
73
74 Compile* C = Compile::current();
75 if (C->alias_type(_adr_type)->is_volatile()) {
76 st->print(" Volatile!");
77 }
78 if (_unaligned_access) {
79 st->print(" unaligned");
80 }
81 if (_mismatched_access) {
82 st->print(" mismatched");
83 }
84 }
85
86 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
87 st->print(" @");
88 if (adr_type == NULL) {
89 st->print("NULL");
90 } else {
91 adr_type->dump_on(st);
92 Compile* C = Compile::current();
93 Compile::AliasType* atp = NULL;
94 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
95 if (atp == NULL)
96 st->print(", idx=?\?;");
97 else if (atp->index() == Compile::AliasIdxBot)
98 st->print(", idx=Bot;");
99 else if (atp->index() == Compile::AliasIdxTop)
100 st->print(", idx=Top;");
101 else if (atp->index() == Compile::AliasIdxRaw)
102 st->print(", idx=Raw;");
103 else {
104 ciField* field = atp->field();
105 if (field) {
106 st->print(", name=");
107 field->print_name_on(st);
108 }
109 st->print(", idx=%d;", atp->index());
110 }
111 }
112 }
113
114 extern void print_alias_types();
115
116 #endif
117
118 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
119 assert((t_oop != NULL), "sanity");
120 bool is_instance = t_oop->is_known_instance_field();
121 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
122 (load != NULL) && load->is_Load() &&
123 (phase->is_IterGVN() != NULL);
124 if (!(is_instance || is_boxed_value_load))
125 return mchain; // don't try to optimize non-instance types
126 uint instance_id = t_oop->instance_id();
127 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
128 Node *prev = NULL;
129 Node *result = mchain;
130 while (prev != result) {
131 prev = result;
132 if (result == start_mem)
133 break; // hit one of our sentinels
134 // skip over a call which does not affect this memory slice
135 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
136 Node *proj_in = result->in(0);
137 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
138 break; // hit one of our sentinels
139 } else if (proj_in->is_Call()) {
140 // ArrayCopyNodes processed here as well
141 CallNode *call = proj_in->as_Call();
142 if (!call->may_modify(t_oop, phase)) { // returns false for instances
143 result = call->in(TypeFunc::Memory);
144 }
145 } else if (proj_in->is_Initialize()) {
146 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
147 // Stop if this is the initialization for the object instance which
148 // contains this memory slice, otherwise skip over it.
149 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
150 break;
151 }
152 if (is_instance) {
153 result = proj_in->in(TypeFunc::Memory);
154 } else if (is_boxed_value_load) {
155 Node* klass = alloc->in(AllocateNode::KlassNode);
156 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
157 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
158 result = proj_in->in(TypeFunc::Memory); // not related allocation
159 }
160 }
161 } else if (proj_in->is_MemBar()) {
162 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase)) {
163 break;
164 }
165 result = proj_in->in(TypeFunc::Memory);
166 } else {
167 assert(false, "unexpected projection");
168 }
169 } else if (result->is_ClearArray()) {
170 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
171 // Can not bypass initialization of the instance
172 // we are looking for.
173 break;
174 }
175 // Otherwise skip it (the call updated 'result' value).
176 } else if (result->is_MergeMem()) {
177 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
178 }
179 }
180 return result;
181 }
182
183 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
184 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
185 if (t_oop == NULL)
186 return mchain; // don't try to optimize non-oop types
187 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
188 bool is_instance = t_oop->is_known_instance_field();
189 PhaseIterGVN *igvn = phase->is_IterGVN();
190 if (is_instance && igvn != NULL && result->is_Phi()) {
191 PhiNode *mphi = result->as_Phi();
192 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
193 const TypePtr *t = mphi->adr_type();
194 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
195 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
196 t->is_oopptr()->cast_to_exactness(true)
197 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
198 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
199 // clone the Phi with our address type
200 result = mphi->split_out_instance(t_adr, igvn);
201 } else {
202 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
203 }
204 }
205 return result;
206 }
207
208 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
209 uint alias_idx = phase->C->get_alias_index(tp);
210 Node *mem = mmem;
211 #ifdef ASSERT
212 {
213 // Check that current type is consistent with the alias index used during graph construction
214 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
215 bool consistent = adr_check == NULL || adr_check->empty() ||
216 phase->C->must_alias(adr_check, alias_idx );
217 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
218 if( !consistent && adr_check != NULL && !adr_check->empty() &&
219 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
220 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
221 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
222 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
223 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
224 // don't assert if it is dead code.
225 consistent = true;
226 }
227 if( !consistent ) {
228 st->print("alias_idx==%d, adr_check==", alias_idx);
229 if( adr_check == NULL ) {
230 st->print("NULL");
231 } else {
232 adr_check->dump();
233 }
234 st->cr();
235 print_alias_types();
236 assert(consistent, "adr_check must match alias idx");
237 }
238 }
239 #endif
240 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
241 // means an array I have not precisely typed yet. Do not do any
242 // alias stuff with it any time soon.
243 const TypeOopPtr *toop = tp->isa_oopptr();
244 if( tp->base() != Type::AnyPtr &&
245 !(toop &&
246 toop->klass() != NULL &&
247 toop->klass()->is_java_lang_Object() &&
248 toop->offset() == Type::OffsetBot) ) {
249 // compress paths and change unreachable cycles to TOP
250 // If not, we can update the input infinitely along a MergeMem cycle
251 // Equivalent code in PhiNode::Ideal
252 Node* m = phase->transform(mmem);
253 // If transformed to a MergeMem, get the desired slice
254 // Otherwise the returned node represents memory for every slice
255 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
256 // Update input if it is progress over what we have now
257 }
258 return mem;
259 }
260
261 //--------------------------Ideal_common---------------------------------------
262 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
263 // Unhook non-raw memories from complete (macro-expanded) initializations.
264 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
265 // If our control input is a dead region, kill all below the region
266 Node *ctl = in(MemNode::Control);
267 if (ctl && remove_dead_region(phase, can_reshape))
268 return this;
269 ctl = in(MemNode::Control);
270 // Don't bother trying to transform a dead node
271 if (ctl && ctl->is_top()) return NodeSentinel;
272
273 PhaseIterGVN *igvn = phase->is_IterGVN();
274 // Wait if control on the worklist.
275 if (ctl && can_reshape && igvn != NULL) {
276 Node* bol = NULL;
277 Node* cmp = NULL;
278 if (ctl->in(0)->is_If()) {
279 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
280 bol = ctl->in(0)->in(1);
281 if (bol->is_Bool())
282 cmp = ctl->in(0)->in(1)->in(1);
283 }
284 if (igvn->_worklist.member(ctl) ||
285 (bol != NULL && igvn->_worklist.member(bol)) ||
286 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
287 // This control path may be dead.
288 // Delay this memory node transformation until the control is processed.
289 phase->is_IterGVN()->_worklist.push(this);
290 return NodeSentinel; // caller will return NULL
291 }
292 }
293 // Ignore if memory is dead, or self-loop
294 Node *mem = in(MemNode::Memory);
295 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
296 assert(mem != this, "dead loop in MemNode::Ideal");
297
298 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
299 // This memory slice may be dead.
300 // Delay this mem node transformation until the memory is processed.
301 phase->is_IterGVN()->_worklist.push(this);
302 return NodeSentinel; // caller will return NULL
303 }
304
305 Node *address = in(MemNode::Address);
306 const Type *t_adr = phase->type(address);
307 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
308
309 if (can_reshape && igvn != NULL &&
310 (igvn->_worklist.member(address) ||
311 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
312 // The address's base and type may change when the address is processed.
313 // Delay this mem node transformation until the address is processed.
314 phase->is_IterGVN()->_worklist.push(this);
315 return NodeSentinel; // caller will return NULL
316 }
317
318 // Do NOT remove or optimize the next lines: ensure a new alias index
319 // is allocated for an oop pointer type before Escape Analysis.
320 // Note: C++ will not remove it since the call has side effect.
321 if (t_adr->isa_oopptr()) {
322 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
323 }
324
325 Node* base = NULL;
326 if (address->is_AddP()) {
327 base = address->in(AddPNode::Base);
328 }
329 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
330 !t_adr->isa_rawptr()) {
331 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
332 // Skip this node optimization if its address has TOP base.
333 return NodeSentinel; // caller will return NULL
334 }
335
336 // Avoid independent memory operations
337 Node* old_mem = mem;
338
339 // The code which unhooks non-raw memories from complete (macro-expanded)
340 // initializations was removed. After macro-expansion all stores catched
341 // by Initialize node became raw stores and there is no information
342 // which memory slices they modify. So it is unsafe to move any memory
343 // operation above these stores. Also in most cases hooked non-raw memories
344 // were already unhooked by using information from detect_ptr_independence()
345 // and find_previous_store().
346
347 if (mem->is_MergeMem()) {
348 MergeMemNode* mmem = mem->as_MergeMem();
349 const TypePtr *tp = t_adr->is_ptr();
350
351 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
352 }
353
354 if (mem != old_mem) {
355 set_req(MemNode::Memory, mem);
356 if (can_reshape && old_mem->outcnt() == 0) {
357 igvn->_worklist.push(old_mem);
358 }
359 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
360 return this;
361 }
362
363 // let the subclass continue analyzing...
364 return NULL;
365 }
366
367 // Helper function for proving some simple control dominations.
368 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
369 // Already assumes that 'dom' is available at 'sub', and that 'sub'
370 // is not a constant (dominated by the method's StartNode).
371 // Used by MemNode::find_previous_store to prove that the
372 // control input of a memory operation predates (dominates)
373 // an allocation it wants to look past.
374 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
375 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
376 return false; // Conservative answer for dead code
377
378 // Check 'dom'. Skip Proj and CatchProj nodes.
379 dom = dom->find_exact_control(dom);
380 if (dom == NULL || dom->is_top())
381 return false; // Conservative answer for dead code
382
383 if (dom == sub) {
384 // For the case when, for example, 'sub' is Initialize and the original
385 // 'dom' is Proj node of the 'sub'.
386 return false;
387 }
388
389 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
390 return true;
391
392 // 'dom' dominates 'sub' if its control edge and control edges
393 // of all its inputs dominate or equal to sub's control edge.
394
395 // Currently 'sub' is either Allocate, Initialize or Start nodes.
396 // Or Region for the check in LoadNode::Ideal();
397 // 'sub' should have sub->in(0) != NULL.
398 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
399 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
400
401 // Get control edge of 'sub'.
402 Node* orig_sub = sub;
403 sub = sub->find_exact_control(sub->in(0));
404 if (sub == NULL || sub->is_top())
405 return false; // Conservative answer for dead code
406
407 assert(sub->is_CFG(), "expecting control");
408
409 if (sub == dom)
410 return true;
411
412 if (sub->is_Start() || sub->is_Root())
413 return false;
414
415 {
416 // Check all control edges of 'dom'.
417
418 ResourceMark rm;
419 Arena* arena = Thread::current()->resource_area();
420 Node_List nlist(arena);
421 Unique_Node_List dom_list(arena);
422
423 dom_list.push(dom);
424 bool only_dominating_controls = false;
425
426 for (uint next = 0; next < dom_list.size(); next++) {
427 Node* n = dom_list.at(next);
428 if (n == orig_sub)
429 return false; // One of dom's inputs dominated by sub.
430 if (!n->is_CFG() && n->pinned()) {
431 // Check only own control edge for pinned non-control nodes.
432 n = n->find_exact_control(n->in(0));
433 if (n == NULL || n->is_top())
434 return false; // Conservative answer for dead code
435 assert(n->is_CFG(), "expecting control");
436 dom_list.push(n);
437 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
438 only_dominating_controls = true;
439 } else if (n->is_CFG()) {
440 if (n->dominates(sub, nlist))
441 only_dominating_controls = true;
442 else
443 return false;
444 } else {
445 // First, own control edge.
446 Node* m = n->find_exact_control(n->in(0));
447 if (m != NULL) {
448 if (m->is_top())
449 return false; // Conservative answer for dead code
450 dom_list.push(m);
451 }
452 // Now, the rest of edges.
453 uint cnt = n->req();
454 for (uint i = 1; i < cnt; i++) {
455 m = n->find_exact_control(n->in(i));
456 if (m == NULL || m->is_top())
457 continue;
458 dom_list.push(m);
459 }
460 }
461 }
462 return only_dominating_controls;
463 }
464 }
465
466 //---------------------detect_ptr_independence---------------------------------
467 // Used by MemNode::find_previous_store to prove that two base
468 // pointers are never equal.
469 // The pointers are accompanied by their associated allocations,
470 // if any, which have been previously discovered by the caller.
471 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
472 Node* p2, AllocateNode* a2,
473 PhaseTransform* phase) {
474 // Attempt to prove that these two pointers cannot be aliased.
475 // They may both manifestly be allocations, and they should differ.
476 // Or, if they are not both allocations, they can be distinct constants.
477 // Otherwise, one is an allocation and the other a pre-existing value.
478 if (a1 == NULL && a2 == NULL) { // neither an allocation
479 return (p1 != p2) && p1->is_Con() && p2->is_Con();
480 } else if (a1 != NULL && a2 != NULL) { // both allocations
481 return (a1 != a2);
482 } else if (a1 != NULL) { // one allocation a1
483 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
484 return all_controls_dominate(p2, a1);
485 } else { //(a2 != NULL) // one allocation a2
486 return all_controls_dominate(p1, a2);
487 }
488 return false;
489 }
490
491
492 // Find an arraycopy that must have set (can_see_stored_value=true) or
493 // could have set (can_see_stored_value=false) the value for this load
494 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
495 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
496 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
497 Node* mb = mem->in(0);
498 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
499 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
500 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
501 if (ac->is_clonebasic()) {
502 intptr_t offset;
503 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
504 assert(alloc != NULL && alloc->initialization()->is_complete_with_arraycopy(), "broken allocation");
505 if (alloc == ld_alloc) {
506 return ac;
507 }
508 }
509 }
510 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
511 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
512
513 if (ac->is_arraycopy_validated() ||
514 ac->is_copyof_validated() ||
515 ac->is_copyofrange_validated()) {
516 Node* ld_addp = in(MemNode::Address);
517 if (ld_addp->is_AddP()) {
518 Node* ld_base = ld_addp->in(AddPNode::Address);
519 Node* ld_offs = ld_addp->in(AddPNode::Offset);
520
521 Node* dest = ac->in(ArrayCopyNode::Dest);
522
523 if (dest == ld_base) {
524 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
525 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
526 return ac;
527 }
528 if (!can_see_stored_value) {
529 mem = ac->in(TypeFunc::Memory);
530 }
531 }
532 }
533 }
534 }
535 return NULL;
536 }
537
538 // The logic for reordering loads and stores uses four steps:
539 // (a) Walk carefully past stores and initializations which we
540 // can prove are independent of this load.
541 // (b) Observe that the next memory state makes an exact match
542 // with self (load or store), and locate the relevant store.
543 // (c) Ensure that, if we were to wire self directly to the store,
544 // the optimizer would fold it up somehow.
545 // (d) Do the rewiring, and return, depending on some other part of
546 // the optimizer to fold up the load.
547 // This routine handles steps (a) and (b). Steps (c) and (d) are
548 // specific to loads and stores, so they are handled by the callers.
549 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
550 //
551 Node* MemNode::find_previous_store(PhaseTransform* phase) {
552 Node* ctrl = in(MemNode::Control);
553 Node* adr = in(MemNode::Address);
554 intptr_t offset = 0;
555 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
556 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
557
558 if (offset == Type::OffsetBot)
559 return NULL; // cannot unalias unless there are precise offsets
560
561 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
562
563 intptr_t size_in_bytes = memory_size();
564
565 Node* mem = in(MemNode::Memory); // start searching here...
566
567 int cnt = 50; // Cycle limiter
568 for (;;) { // While we can dance past unrelated stores...
569 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
570
571 Node* prev = mem;
572 if (mem->is_Store()) {
573 Node* st_adr = mem->in(MemNode::Address);
574 intptr_t st_offset = 0;
575 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
576 if (st_base == NULL)
577 break; // inscrutable pointer
578 if (st_offset != offset && st_offset != Type::OffsetBot) {
579 const int MAX_STORE = BytesPerLong;
580 if (st_offset >= offset + size_in_bytes ||
581 st_offset <= offset - MAX_STORE ||
582 st_offset <= offset - mem->as_Store()->memory_size()) {
583 // Success: The offsets are provably independent.
584 // (You may ask, why not just test st_offset != offset and be done?
585 // The answer is that stores of different sizes can co-exist
586 // in the same sequence of RawMem effects. We sometimes initialize
587 // a whole 'tile' of array elements with a single jint or jlong.)
588 mem = mem->in(MemNode::Memory);
589 continue; // (a) advance through independent store memory
590 }
591 }
592 if (st_base != base &&
593 detect_ptr_independence(base, alloc,
594 st_base,
595 AllocateNode::Ideal_allocation(st_base, phase),
596 phase)) {
597 // Success: The bases are provably independent.
598 mem = mem->in(MemNode::Memory);
599 continue; // (a) advance through independent store memory
600 }
601
602 // (b) At this point, if the bases or offsets do not agree, we lose,
603 // since we have not managed to prove 'this' and 'mem' independent.
604 if (st_base == base && st_offset == offset) {
605 return mem; // let caller handle steps (c), (d)
606 }
607
608 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
609 InitializeNode* st_init = mem->in(0)->as_Initialize();
610 AllocateNode* st_alloc = st_init->allocation();
611 if (st_alloc == NULL)
612 break; // something degenerated
613 bool known_identical = false;
614 bool known_independent = false;
615 if (alloc == st_alloc)
616 known_identical = true;
617 else if (alloc != NULL)
618 known_independent = true;
619 else if (all_controls_dominate(this, st_alloc))
620 known_independent = true;
621
622 if (known_independent) {
623 // The bases are provably independent: Either they are
624 // manifestly distinct allocations, or else the control
625 // of this load dominates the store's allocation.
626 int alias_idx = phase->C->get_alias_index(adr_type());
627 if (alias_idx == Compile::AliasIdxRaw) {
628 mem = st_alloc->in(TypeFunc::Memory);
629 } else {
630 mem = st_init->memory(alias_idx);
631 }
632 continue; // (a) advance through independent store memory
633 }
634
635 // (b) at this point, if we are not looking at a store initializing
636 // the same allocation we are loading from, we lose.
637 if (known_identical) {
638 // From caller, can_see_stored_value will consult find_captured_store.
639 return mem; // let caller handle steps (c), (d)
640 }
641
642 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
643 if (prev != mem) {
644 // Found an arraycopy but it doesn't affect that load
645 continue;
646 }
647 // Found an arraycopy that may affect that load
648 return mem;
649 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
650 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
651 if (mem->is_Proj() && mem->in(0)->is_Call()) {
652 // ArrayCopyNodes processed here as well.
653 CallNode *call = mem->in(0)->as_Call();
654 if (!call->may_modify(addr_t, phase)) {
655 mem = call->in(TypeFunc::Memory);
656 continue; // (a) advance through independent call memory
657 }
658 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
659 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase)) {
660 break;
661 }
662 mem = mem->in(0)->in(TypeFunc::Memory);
663 continue; // (a) advance through independent MemBar memory
664 } else if (mem->is_ClearArray()) {
665 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
666 // (the call updated 'mem' value)
667 continue; // (a) advance through independent allocation memory
668 } else {
669 // Can not bypass initialization of the instance
670 // we are looking for.
671 return mem;
672 }
673 } else if (mem->is_MergeMem()) {
674 int alias_idx = phase->C->get_alias_index(adr_type());
675 mem = mem->as_MergeMem()->memory_at(alias_idx);
676 continue; // (a) advance through independent MergeMem memory
677 }
678 }
679
680 // Unless there is an explicit 'continue', we must bail out here,
681 // because 'mem' is an inscrutable memory state (e.g., a call).
682 break;
683 }
684
685 return NULL; // bail out
686 }
687
688 //----------------------calculate_adr_type-------------------------------------
689 // Helper function. Notices when the given type of address hits top or bottom.
690 // Also, asserts a cross-check of the type against the expected address type.
691 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
692 if (t == Type::TOP) return NULL; // does not touch memory any more?
693 #ifdef PRODUCT
694 cross_check = NULL;
695 #else
696 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
697 #endif
698 const TypePtr* tp = t->isa_ptr();
699 if (tp == NULL) {
700 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
701 return TypePtr::BOTTOM; // touches lots of memory
702 } else {
703 #ifdef ASSERT
704 // %%%% [phh] We don't check the alias index if cross_check is
705 // TypeRawPtr::BOTTOM. Needs to be investigated.
706 if (cross_check != NULL &&
707 cross_check != TypePtr::BOTTOM &&
708 cross_check != TypeRawPtr::BOTTOM) {
709 // Recheck the alias index, to see if it has changed (due to a bug).
710 Compile* C = Compile::current();
711 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
712 "must stay in the original alias category");
713 // The type of the address must be contained in the adr_type,
714 // disregarding "null"-ness.
715 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
716 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
717 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
718 "real address must not escape from expected memory type");
719 }
720 #endif
721 return tp;
722 }
723 }
724
725 //=============================================================================
726 // Should LoadNode::Ideal() attempt to remove control edges?
727 bool LoadNode::can_remove_control() const {
728 return true;
729 }
730 uint LoadNode::size_of() const { return sizeof(*this); }
731 uint LoadNode::cmp( const Node &n ) const
732 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
733 const Type *LoadNode::bottom_type() const { return _type; }
734 uint LoadNode::ideal_reg() const {
735 return _type->ideal_reg();
736 }
737
738 #ifndef PRODUCT
739 void LoadNode::dump_spec(outputStream *st) const {
740 MemNode::dump_spec(st);
741 if( !Verbose && !WizardMode ) {
742 // standard dump does this in Verbose and WizardMode
743 st->print(" #"); _type->dump_on(st);
744 }
745 if (!depends_only_on_test()) {
746 st->print(" (does not depend only on test)");
747 }
748 }
749 #endif
750
751 #ifdef ASSERT
752 //----------------------------is_immutable_value-------------------------------
753 // Helper function to allow a raw load without control edge for some cases
754 bool LoadNode::is_immutable_value(Node* adr) {
755 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
756 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
757 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
758 in_bytes(JavaThread::osthread_offset())));
759 }
760 #endif
761
762 //----------------------------LoadNode::make-----------------------------------
763 // Polymorphic factory method:
764 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
765 ControlDependency control_dependency, bool unaligned, bool mismatched) {
766 Compile* C = gvn.C;
767
768 // sanity check the alias category against the created node type
769 assert(!(adr_type->isa_oopptr() &&
770 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
771 "use LoadKlassNode instead");
772 assert(!(adr_type->isa_aryptr() &&
773 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
774 "use LoadRangeNode instead");
775 // Check control edge of raw loads
776 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
777 // oop will be recorded in oop map if load crosses safepoint
778 rt->isa_oopptr() || is_immutable_value(adr),
779 "raw memory operations should have control edge");
780 LoadNode* load = NULL;
781 switch (bt) {
782 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
783 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
784 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
785 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
786 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
787 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
788 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
789 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
790 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
791 case T_OBJECT:
792 #ifdef _LP64
793 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
794 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
795 } else
796 #endif
797 {
798 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
799 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
800 }
801 break;
802 }
803 assert(load != NULL, "LoadNode should have been created");
804 if (unaligned) {
805 load->set_unaligned_access();
806 }
807 if (mismatched) {
808 load->set_mismatched_access();
809 }
810 if (load->Opcode() == Op_LoadN) {
811 Node* ld = gvn.transform(load);
812 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
813 }
814
815 return load;
816 }
817
818 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
819 ControlDependency control_dependency, bool unaligned, bool mismatched) {
820 bool require_atomic = true;
821 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
822 if (unaligned) {
823 load->set_unaligned_access();
824 }
825 if (mismatched) {
826 load->set_mismatched_access();
827 }
828 return load;
829 }
830
831 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
832 ControlDependency control_dependency, bool unaligned, bool mismatched) {
833 bool require_atomic = true;
834 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
835 if (unaligned) {
836 load->set_unaligned_access();
837 }
838 if (mismatched) {
839 load->set_mismatched_access();
840 }
841 return load;
842 }
843
844
845
846 //------------------------------hash-------------------------------------------
847 uint LoadNode::hash() const {
848 // unroll addition of interesting fields
849 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
850 }
851
852 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
853 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
854 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
855 bool is_stable_ary = FoldStableValues &&
856 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
857 tp->isa_aryptr()->is_stable();
858
859 return (eliminate_boxing && non_volatile) || is_stable_ary;
860 }
861
862 return false;
863 }
864
865 // Is the value loaded previously stored by an arraycopy? If so return
866 // a load node that reads from the source array so we may be able to
867 // optimize out the ArrayCopy node later.
868 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const {
869 Node* ld_adr = in(MemNode::Address);
870 intptr_t ld_off = 0;
871 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
872 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
873 if (ac != NULL) {
874 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
875
876 Node* ld = clone();
877 if (ac->as_ArrayCopy()->is_clonebasic()) {
878 assert(ld_alloc != NULL, "need an alloc");
879 Node* addp = in(MemNode::Address)->clone();
880 assert(addp->is_AddP(), "address must be addp");
881 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
882 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
883 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base));
884 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address));
885 ld->set_req(MemNode::Address, phase->transform(addp));
886 if (in(0) != NULL) {
887 assert(ld_alloc->in(0) != NULL, "alloc must have control");
888 ld->set_req(0, ld_alloc->in(0));
889 }
890 } else {
891 Node* addp = in(MemNode::Address)->clone();
892 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
893 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src));
894 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src));
895
896 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
897 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
898 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
899 uint shift = exact_log2(type2aelembytes(ary_elem));
900
901 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
902 #ifdef _LP64
903 diff = phase->transform(new ConvI2LNode(diff));
904 #endif
905 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
906
907 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
908 addp->set_req(AddPNode::Offset, offset);
909 ld->set_req(MemNode::Address, phase->transform(addp));
910
911 if (in(0) != NULL) {
912 assert(ac->in(0) != NULL, "alloc must have control");
913 ld->set_req(0, ac->in(0));
914 }
915 }
916 // load depends on the tests that validate the arraycopy
917 ld->as_Load()->_control_dependency = Pinned;
918 return ld;
919 }
920 return NULL;
921 }
922
923
924 //---------------------------can_see_stored_value------------------------------
925 // This routine exists to make sure this set of tests is done the same
926 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
927 // will change the graph shape in a way which makes memory alive twice at the
928 // same time (uses the Oracle model of aliasing), then some
929 // LoadXNode::Identity will fold things back to the equivalence-class model
930 // of aliasing.
931 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
932 Node* ld_adr = in(MemNode::Address);
933 intptr_t ld_off = 0;
934 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
935 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
936 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
937 // This is more general than load from boxing objects.
938 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
939 uint alias_idx = atp->index();
940 bool final = !atp->is_rewritable();
941 Node* result = NULL;
942 Node* current = st;
943 // Skip through chains of MemBarNodes checking the MergeMems for
944 // new states for the slice of this load. Stop once any other
945 // kind of node is encountered. Loads from final memory can skip
946 // through any kind of MemBar but normal loads shouldn't skip
947 // through MemBarAcquire since the could allow them to move out of
948 // a synchronized region.
949 while (current->is_Proj()) {
950 int opc = current->in(0)->Opcode();
951 if ((final && (opc == Op_MemBarAcquire ||
952 opc == Op_MemBarAcquireLock ||
953 opc == Op_LoadFence)) ||
954 opc == Op_MemBarRelease ||
955 opc == Op_StoreFence ||
956 opc == Op_MemBarReleaseLock ||
957 opc == Op_MemBarStoreStore ||
958 opc == Op_MemBarCPUOrder) {
959 Node* mem = current->in(0)->in(TypeFunc::Memory);
960 if (mem->is_MergeMem()) {
961 MergeMemNode* merge = mem->as_MergeMem();
962 Node* new_st = merge->memory_at(alias_idx);
963 if (new_st == merge->base_memory()) {
964 // Keep searching
965 current = new_st;
966 continue;
967 }
968 // Save the new memory state for the slice and fall through
969 // to exit.
970 result = new_st;
971 }
972 }
973 break;
974 }
975 if (result != NULL) {
976 st = result;
977 }
978 }
979
980 // Loop around twice in the case Load -> Initialize -> Store.
981 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
982 for (int trip = 0; trip <= 1; trip++) {
983
984 if (st->is_Store()) {
985 Node* st_adr = st->in(MemNode::Address);
986 if (!phase->eqv(st_adr, ld_adr)) {
987 // Try harder before giving up... Match raw and non-raw pointers.
988 intptr_t st_off = 0;
989 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
990 if (alloc == NULL) return NULL;
991 if (alloc != ld_alloc) return NULL;
992 if (ld_off != st_off) return NULL;
993 // At this point we have proven something like this setup:
994 // A = Allocate(...)
995 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
996 // S = StoreQ(, AddP(, A.Parm , #Off), V)
997 // (Actually, we haven't yet proven the Q's are the same.)
998 // In other words, we are loading from a casted version of
999 // the same pointer-and-offset that we stored to.
1000 // Thus, we are able to replace L by V.
1001 }
1002 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1003 if (store_Opcode() != st->Opcode())
1004 return NULL;
1005 return st->in(MemNode::ValueIn);
1006 }
1007
1008 // A load from a freshly-created object always returns zero.
1009 // (This can happen after LoadNode::Ideal resets the load's memory input
1010 // to find_captured_store, which returned InitializeNode::zero_memory.)
1011 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1012 (st->in(0) == ld_alloc) &&
1013 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1014 // return a zero value for the load's basic type
1015 // (This is one of the few places where a generic PhaseTransform
1016 // can create new nodes. Think of it as lazily manifesting
1017 // virtually pre-existing constants.)
1018 return phase->zerocon(memory_type());
1019 }
1020
1021 // A load from an initialization barrier can match a captured store.
1022 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1023 InitializeNode* init = st->in(0)->as_Initialize();
1024 AllocateNode* alloc = init->allocation();
1025 if ((alloc != NULL) && (alloc == ld_alloc)) {
1026 // examine a captured store value
1027 st = init->find_captured_store(ld_off, memory_size(), phase);
1028 if (st != NULL) {
1029 continue; // take one more trip around
1030 }
1031 }
1032 }
1033
1034 // Load boxed value from result of valueOf() call is input parameter.
1035 if (this->is_Load() && ld_adr->is_AddP() &&
1036 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1037 intptr_t ignore = 0;
1038 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1039 if (base != NULL && base->is_Proj() &&
1040 base->as_Proj()->_con == TypeFunc::Parms &&
1041 base->in(0)->is_CallStaticJava() &&
1042 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1043 return base->in(0)->in(TypeFunc::Parms);
1044 }
1045 }
1046
1047 break;
1048 }
1049
1050 return NULL;
1051 }
1052
1053 //----------------------is_instance_field_load_with_local_phi------------------
1054 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1055 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1056 in(Address)->is_AddP() ) {
1057 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1058 // Only instances and boxed values.
1059 if( t_oop != NULL &&
1060 (t_oop->is_ptr_to_boxed_value() ||
1061 t_oop->is_known_instance_field()) &&
1062 t_oop->offset() != Type::OffsetBot &&
1063 t_oop->offset() != Type::OffsetTop) {
1064 return true;
1065 }
1066 }
1067 return false;
1068 }
1069
1070 //------------------------------Identity---------------------------------------
1071 // Loads are identity if previous store is to same address
1072 Node* LoadNode::Identity(PhaseGVN* phase) {
1073 // If the previous store-maker is the right kind of Store, and the store is
1074 // to the same address, then we are equal to the value stored.
1075 Node* mem = in(Memory);
1076 Node* value = can_see_stored_value(mem, phase);
1077 if( value ) {
1078 // byte, short & char stores truncate naturally.
1079 // A load has to load the truncated value which requires
1080 // some sort of masking operation and that requires an
1081 // Ideal call instead of an Identity call.
1082 if (memory_size() < BytesPerInt) {
1083 // If the input to the store does not fit with the load's result type,
1084 // it must be truncated via an Ideal call.
1085 if (!phase->type(value)->higher_equal(phase->type(this)))
1086 return this;
1087 }
1088 // (This works even when value is a Con, but LoadNode::Value
1089 // usually runs first, producing the singleton type of the Con.)
1090 return value;
1091 }
1092
1093 // Search for an existing data phi which was generated before for the same
1094 // instance's field to avoid infinite generation of phis in a loop.
1095 Node *region = mem->in(0);
1096 if (is_instance_field_load_with_local_phi(region)) {
1097 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1098 int this_index = phase->C->get_alias_index(addr_t);
1099 int this_offset = addr_t->offset();
1100 int this_iid = addr_t->instance_id();
1101 if (!addr_t->is_known_instance() &&
1102 addr_t->is_ptr_to_boxed_value()) {
1103 // Use _idx of address base (could be Phi node) for boxed values.
1104 intptr_t ignore = 0;
1105 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1106 this_iid = base->_idx;
1107 }
1108 const Type* this_type = bottom_type();
1109 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1110 Node* phi = region->fast_out(i);
1111 if (phi->is_Phi() && phi != mem &&
1112 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1113 return phi;
1114 }
1115 }
1116 }
1117
1118 return this;
1119 }
1120
1121 // Construct an equivalent unsigned load.
1122 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1123 BasicType bt = T_ILLEGAL;
1124 const Type* rt = NULL;
1125 switch (Opcode()) {
1126 case Op_LoadUB: return this;
1127 case Op_LoadUS: return this;
1128 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1129 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1130 default:
1131 assert(false, "no unsigned variant");
1132 return NULL;
1133 }
1134 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1135 adr_type(), rt, bt, _mo, _control_dependency,
1136 is_unaligned_access(), is_mismatched_access());
1137 }
1138
1139 // Construct an equivalent signed load.
1140 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1141 BasicType bt = T_ILLEGAL;
1142 const Type* rt = NULL;
1143 switch (Opcode()) {
1144 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1145 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1146 default:
1147 return this; // All other loads are signed.
1148 }
1149 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1150 adr_type(), rt, bt, _mo, _control_dependency,
1151 is_unaligned_access(), is_mismatched_access());
1152 }
1153
1154 // We're loading from an object which has autobox behaviour.
1155 // If this object is result of a valueOf call we'll have a phi
1156 // merging a newly allocated object and a load from the cache.
1157 // We want to replace this load with the original incoming
1158 // argument to the valueOf call.
1159 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1160 assert(phase->C->eliminate_boxing(), "sanity");
1161 intptr_t ignore = 0;
1162 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1163 if ((base == NULL) || base->is_Phi()) {
1164 // Push the loads from the phi that comes from valueOf up
1165 // through it to allow elimination of the loads and the recovery
1166 // of the original value. It is done in split_through_phi().
1167 return NULL;
1168 } else if (base->is_Load() ||
1169 base->is_DecodeN() && base->in(1)->is_Load()) {
1170 // Eliminate the load of boxed value for integer types from the cache
1171 // array by deriving the value from the index into the array.
1172 // Capture the offset of the load and then reverse the computation.
1173
1174 // Get LoadN node which loads a boxing object from 'cache' array.
1175 if (base->is_DecodeN()) {
1176 base = base->in(1);
1177 }
1178 if (!base->in(Address)->is_AddP()) {
1179 return NULL; // Complex address
1180 }
1181 AddPNode* address = base->in(Address)->as_AddP();
1182 Node* cache_base = address->in(AddPNode::Base);
1183 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1184 // Get ConP node which is static 'cache' field.
1185 cache_base = cache_base->in(1);
1186 }
1187 if ((cache_base != NULL) && cache_base->is_Con()) {
1188 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1189 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1190 Node* elements[4];
1191 int shift = exact_log2(type2aelembytes(T_OBJECT));
1192 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1193 if ((count > 0) && elements[0]->is_Con() &&
1194 ((count == 1) ||
1195 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1196 elements[1]->in(2) == phase->intcon(shift))) {
1197 ciObjArray* array = base_type->const_oop()->as_obj_array();
1198 // Fetch the box object cache[0] at the base of the array and get its value
1199 ciInstance* box = array->obj_at(0)->as_instance();
1200 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1201 assert(ik->is_box_klass(), "sanity");
1202 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1203 if (ik->nof_nonstatic_fields() == 1) {
1204 // This should be true nonstatic_field_at requires calling
1205 // nof_nonstatic_fields so check it anyway
1206 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1207 BasicType bt = c.basic_type();
1208 // Only integer types have boxing cache.
1209 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1210 bt == T_BYTE || bt == T_SHORT ||
1211 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1212 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1213 if (cache_low != (int)cache_low) {
1214 return NULL; // should not happen since cache is array indexed by value
1215 }
1216 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1217 if (offset != (int)offset) {
1218 return NULL; // should not happen since cache is array indexed by value
1219 }
1220 // Add up all the offsets making of the address of the load
1221 Node* result = elements[0];
1222 for (int i = 1; i < count; i++) {
1223 result = phase->transform(new AddXNode(result, elements[i]));
1224 }
1225 // Remove the constant offset from the address and then
1226 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1227 // remove the scaling of the offset to recover the original index.
1228 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1229 // Peel the shift off directly but wrap it in a dummy node
1230 // since Ideal can't return existing nodes
1231 result = new RShiftXNode(result->in(1), phase->intcon(0));
1232 } else if (result->is_Add() && result->in(2)->is_Con() &&
1233 result->in(1)->Opcode() == Op_LShiftX &&
1234 result->in(1)->in(2) == phase->intcon(shift)) {
1235 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1236 // but for boxing cache access we know that X<<Z will not overflow
1237 // (there is range check) so we do this optimizatrion by hand here.
1238 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1239 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1240 } else {
1241 result = new RShiftXNode(result, phase->intcon(shift));
1242 }
1243 #ifdef _LP64
1244 if (bt != T_LONG) {
1245 result = new ConvL2INode(phase->transform(result));
1246 }
1247 #else
1248 if (bt == T_LONG) {
1249 result = new ConvI2LNode(phase->transform(result));
1250 }
1251 #endif
1252 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1253 // Need to preserve unboxing load type if it is unsigned.
1254 switch(this->Opcode()) {
1255 case Op_LoadUB:
1256 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1257 break;
1258 case Op_LoadUS:
1259 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1260 break;
1261 }
1262 return result;
1263 }
1264 }
1265 }
1266 }
1267 }
1268 return NULL;
1269 }
1270
1271 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1272 Node* region = phi->in(0);
1273 if (region == NULL) {
1274 return false; // Wait stable graph
1275 }
1276 uint cnt = phi->req();
1277 for (uint i = 1; i < cnt; i++) {
1278 Node* rc = region->in(i);
1279 if (rc == NULL || phase->type(rc) == Type::TOP)
1280 return false; // Wait stable graph
1281 Node* in = phi->in(i);
1282 if (in == NULL || phase->type(in) == Type::TOP)
1283 return false; // Wait stable graph
1284 }
1285 return true;
1286 }
1287 //------------------------------split_through_phi------------------------------
1288 // Split instance or boxed field load through Phi.
1289 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1290 Node* mem = in(Memory);
1291 Node* address = in(Address);
1292 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1293
1294 assert((t_oop != NULL) &&
1295 (t_oop->is_known_instance_field() ||
1296 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1297
1298 Compile* C = phase->C;
1299 intptr_t ignore = 0;
1300 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1301 bool base_is_phi = (base != NULL) && base->is_Phi();
1302 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1303 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1304 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1305
1306 if (!((mem->is_Phi() || base_is_phi) &&
1307 (load_boxed_values || t_oop->is_known_instance_field()))) {
1308 return NULL; // memory is not Phi
1309 }
1310
1311 if (mem->is_Phi()) {
1312 if (!stable_phi(mem->as_Phi(), phase)) {
1313 return NULL; // Wait stable graph
1314 }
1315 uint cnt = mem->req();
1316 // Check for loop invariant memory.
1317 if (cnt == 3) {
1318 for (uint i = 1; i < cnt; i++) {
1319 Node* in = mem->in(i);
1320 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1321 if (m == mem) {
1322 set_req(Memory, mem->in(cnt - i));
1323 return this; // made change
1324 }
1325 }
1326 }
1327 }
1328 if (base_is_phi) {
1329 if (!stable_phi(base->as_Phi(), phase)) {
1330 return NULL; // Wait stable graph
1331 }
1332 uint cnt = base->req();
1333 // Check for loop invariant memory.
1334 if (cnt == 3) {
1335 for (uint i = 1; i < cnt; i++) {
1336 if (base->in(i) == base) {
1337 return NULL; // Wait stable graph
1338 }
1339 }
1340 }
1341 }
1342
1343 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1344
1345 // Split through Phi (see original code in loopopts.cpp).
1346 assert(C->have_alias_type(t_oop), "instance should have alias type");
1347
1348 // Do nothing here if Identity will find a value
1349 // (to avoid infinite chain of value phis generation).
1350 if (!phase->eqv(this, this->Identity(phase)))
1351 return NULL;
1352
1353 // Select Region to split through.
1354 Node* region;
1355 if (!base_is_phi) {
1356 assert(mem->is_Phi(), "sanity");
1357 region = mem->in(0);
1358 // Skip if the region dominates some control edge of the address.
1359 if (!MemNode::all_controls_dominate(address, region))
1360 return NULL;
1361 } else if (!mem->is_Phi()) {
1362 assert(base_is_phi, "sanity");
1363 region = base->in(0);
1364 // Skip if the region dominates some control edge of the memory.
1365 if (!MemNode::all_controls_dominate(mem, region))
1366 return NULL;
1367 } else if (base->in(0) != mem->in(0)) {
1368 assert(base_is_phi && mem->is_Phi(), "sanity");
1369 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1370 region = base->in(0);
1371 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1372 region = mem->in(0);
1373 } else {
1374 return NULL; // complex graph
1375 }
1376 } else {
1377 assert(base->in(0) == mem->in(0), "sanity");
1378 region = mem->in(0);
1379 }
1380
1381 const Type* this_type = this->bottom_type();
1382 int this_index = C->get_alias_index(t_oop);
1383 int this_offset = t_oop->offset();
1384 int this_iid = t_oop->instance_id();
1385 if (!t_oop->is_known_instance() && load_boxed_values) {
1386 // Use _idx of address base for boxed values.
1387 this_iid = base->_idx;
1388 }
1389 PhaseIterGVN* igvn = phase->is_IterGVN();
1390 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1391 for (uint i = 1; i < region->req(); i++) {
1392 Node* x;
1393 Node* the_clone = NULL;
1394 if (region->in(i) == C->top()) {
1395 x = C->top(); // Dead path? Use a dead data op
1396 } else {
1397 x = this->clone(); // Else clone up the data op
1398 the_clone = x; // Remember for possible deletion.
1399 // Alter data node to use pre-phi inputs
1400 if (this->in(0) == region) {
1401 x->set_req(0, region->in(i));
1402 } else {
1403 x->set_req(0, NULL);
1404 }
1405 if (mem->is_Phi() && (mem->in(0) == region)) {
1406 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1407 }
1408 if (address->is_Phi() && address->in(0) == region) {
1409 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1410 }
1411 if (base_is_phi && (base->in(0) == region)) {
1412 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1413 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1414 x->set_req(Address, adr_x);
1415 }
1416 }
1417 // Check for a 'win' on some paths
1418 const Type *t = x->Value(igvn);
1419
1420 bool singleton = t->singleton();
1421
1422 // See comments in PhaseIdealLoop::split_thru_phi().
1423 if (singleton && t == Type::TOP) {
1424 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1425 }
1426
1427 if (singleton) {
1428 x = igvn->makecon(t);
1429 } else {
1430 // We now call Identity to try to simplify the cloned node.
1431 // Note that some Identity methods call phase->type(this).
1432 // Make sure that the type array is big enough for
1433 // our new node, even though we may throw the node away.
1434 // (This tweaking with igvn only works because x is a new node.)
1435 igvn->set_type(x, t);
1436 // If x is a TypeNode, capture any more-precise type permanently into Node
1437 // otherwise it will be not updated during igvn->transform since
1438 // igvn->type(x) is set to x->Value() already.
1439 x->raise_bottom_type(t);
1440 Node *y = x->Identity(igvn);
1441 if (y != x) {
1442 x = y;
1443 } else {
1444 y = igvn->hash_find_insert(x);
1445 if (y) {
1446 x = y;
1447 } else {
1448 // Else x is a new node we are keeping
1449 // We do not need register_new_node_with_optimizer
1450 // because set_type has already been called.
1451 igvn->_worklist.push(x);
1452 }
1453 }
1454 }
1455 if (x != the_clone && the_clone != NULL) {
1456 igvn->remove_dead_node(the_clone);
1457 }
1458 phi->set_req(i, x);
1459 }
1460 // Record Phi
1461 igvn->register_new_node_with_optimizer(phi);
1462 return phi;
1463 }
1464
1465 //------------------------------Ideal------------------------------------------
1466 // If the load is from Field memory and the pointer is non-null, it might be possible to
1467 // zero out the control input.
1468 // If the offset is constant and the base is an object allocation,
1469 // try to hook me up to the exact initializing store.
1470 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1471 Node* p = MemNode::Ideal_common(phase, can_reshape);
1472 if (p) return (p == NodeSentinel) ? NULL : p;
1473
1474 Node* ctrl = in(MemNode::Control);
1475 Node* address = in(MemNode::Address);
1476 bool progress = false;
1477
1478 // Skip up past a SafePoint control. Cannot do this for Stores because
1479 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1480 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1481 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1482 ctrl = ctrl->in(0);
1483 set_req(MemNode::Control,ctrl);
1484 progress = true;
1485 }
1486
1487 intptr_t ignore = 0;
1488 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1489 if (base != NULL
1490 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1491 // Check for useless control edge in some common special cases
1492 if (in(MemNode::Control) != NULL
1493 && can_remove_control()
1494 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1495 && all_controls_dominate(base, phase->C->start())) {
1496 // A method-invariant, non-null address (constant or 'this' argument).
1497 set_req(MemNode::Control, NULL);
1498 progress = true;
1499 }
1500 }
1501
1502 Node* mem = in(MemNode::Memory);
1503 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1504
1505 if (can_reshape && (addr_t != NULL)) {
1506 // try to optimize our memory input
1507 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1508 if (opt_mem != mem) {
1509 set_req(MemNode::Memory, opt_mem);
1510 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1511 return this;
1512 }
1513 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1514 if ((t_oop != NULL) &&
1515 (t_oop->is_known_instance_field() ||
1516 t_oop->is_ptr_to_boxed_value())) {
1517 PhaseIterGVN *igvn = phase->is_IterGVN();
1518 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1519 // Delay this transformation until memory Phi is processed.
1520 phase->is_IterGVN()->_worklist.push(this);
1521 return NULL;
1522 }
1523 // Split instance field load through Phi.
1524 Node* result = split_through_phi(phase);
1525 if (result != NULL) return result;
1526
1527 if (t_oop->is_ptr_to_boxed_value()) {
1528 Node* result = eliminate_autobox(phase);
1529 if (result != NULL) return result;
1530 }
1531 }
1532 }
1533
1534 // Is there a dominating load that loads the same value? Leave
1535 // anything that is not a load of a field/array element (like
1536 // barriers etc.) alone
1537 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1538 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1539 Node *use = mem->fast_out(i);
1540 if (use != this &&
1541 use->Opcode() == Opcode() &&
1542 use->in(0) != NULL &&
1543 use->in(0) != in(0) &&
1544 use->in(Address) == in(Address)) {
1545 Node* ctl = in(0);
1546 for (int i = 0; i < 10 && ctl != NULL; i++) {
1547 ctl = IfNode::up_one_dom(ctl);
1548 if (ctl == use->in(0)) {
1549 set_req(0, use->in(0));
1550 return this;
1551 }
1552 }
1553 }
1554 }
1555 }
1556
1557 // Check for prior store with a different base or offset; make Load
1558 // independent. Skip through any number of them. Bail out if the stores
1559 // are in an endless dead cycle and report no progress. This is a key
1560 // transform for Reflection. However, if after skipping through the Stores
1561 // we can't then fold up against a prior store do NOT do the transform as
1562 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1563 // array memory alive twice: once for the hoisted Load and again after the
1564 // bypassed Store. This situation only works if EVERYBODY who does
1565 // anti-dependence work knows how to bypass. I.e. we need all
1566 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1567 // the alias index stuff. So instead, peek through Stores and IFF we can
1568 // fold up, do so.
1569 Node* prev_mem = find_previous_store(phase);
1570 if (prev_mem != NULL) {
1571 Node* value = can_see_arraycopy_value(prev_mem, phase);
1572 if (value != NULL) {
1573 return value;
1574 }
1575 }
1576 // Steps (a), (b): Walk past independent stores to find an exact match.
1577 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1578 // (c) See if we can fold up on the spot, but don't fold up here.
1579 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1580 // just return a prior value, which is done by Identity calls.
1581 if (can_see_stored_value(prev_mem, phase)) {
1582 // Make ready for step (d):
1583 set_req(MemNode::Memory, prev_mem);
1584 return this;
1585 }
1586 }
1587
1588 return progress ? this : NULL;
1589 }
1590
1591 // Helper to recognize certain Klass fields which are invariant across
1592 // some group of array types (e.g., int[] or all T[] where T < Object).
1593 const Type*
1594 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1595 ciKlass* klass) const {
1596 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1597 // The field is Klass::_modifier_flags. Return its (constant) value.
1598 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1599 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1600 return TypeInt::make(klass->modifier_flags());
1601 }
1602 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1603 // The field is Klass::_access_flags. Return its (constant) value.
1604 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1605 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1606 return TypeInt::make(klass->access_flags());
1607 }
1608 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1609 // The field is Klass::_layout_helper. Return its constant value if known.
1610 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1611 return TypeInt::make(klass->layout_helper());
1612 }
1613
1614 // No match.
1615 return NULL;
1616 }
1617
1618 static ciConstant check_mismatched_access(ciConstant con, BasicType loadbt, bool is_unsigned) {
1619 BasicType conbt = con.basic_type();
1620 switch (conbt) {
1621 case T_BOOLEAN: conbt = T_BYTE; break;
1622 case T_ARRAY: conbt = T_OBJECT; break;
1623 }
1624 switch (loadbt) {
1625 case T_BOOLEAN: loadbt = T_BYTE; break;
1626 case T_NARROWOOP: loadbt = T_OBJECT; break;
1627 case T_ARRAY: loadbt = T_OBJECT; break;
1628 case T_ADDRESS: loadbt = T_OBJECT; break;
1629 }
1630 if (conbt == loadbt) {
1631 if (is_unsigned && conbt == T_BYTE) {
1632 // LoadB (T_BYTE) with a small mask (<=8-bit) is converted to LoadUB (T_BYTE).
1633 return ciConstant(T_INT, con.as_int() & 0xFF);
1634 } else {
1635 return con;
1636 }
1637 }
1638 if (conbt == T_SHORT && loadbt == T_CHAR) {
1639 // LoadS (T_SHORT) with a small mask (<=16-bit) is converted to LoadUS (T_CHAR).
1640 return ciConstant(T_INT, con.as_int() & 0xFFFF);
1641 }
1642 return ciConstant(); // T_ILLEGAL
1643 }
1644
1645 // Try to constant-fold a stable array element.
1646 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, bool is_unsigned_load, BasicType loadbt) {
1647 assert(ary->const_oop(), "array should be constant");
1648 assert(ary->is_stable(), "array should be stable");
1649
1650 // Decode the results of GraphKit::array_element_address.
1651 ciArray* aobj = ary->const_oop()->as_array();
1652 ciConstant element_value = aobj->element_value_by_offset(off);
1653 if (element_value.basic_type() == T_ILLEGAL) {
1654 return NULL; // wrong offset
1655 }
1656 ciConstant con = check_mismatched_access(element_value, loadbt, is_unsigned_load);
1657 assert(con.basic_type() != T_ILLEGAL, "elembt=%s; loadbt=%s; unsigned=%d",
1658 type2name(element_value.basic_type()), type2name(loadbt), is_unsigned_load);
1659
1660 if (con.basic_type() != T_ILLEGAL && // not a mismatched access
1661 !con.is_null_or_zero()) { // not a default value
1662 const Type* con_type = Type::make_from_constant(con);
1663 if (con_type != NULL) {
1664 if (con_type->isa_aryptr()) {
1665 // Join with the array element type, in case it is also stable.
1666 int dim = ary->stable_dimension();
1667 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1668 }
1669 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1670 con_type = con_type->make_narrowoop();
1671 }
1672 #ifndef PRODUCT
1673 if (TraceIterativeGVN) {
1674 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1675 con_type->dump(); tty->cr();
1676 }
1677 #endif //PRODUCT
1678 return con_type;
1679 }
1680 }
1681 return NULL;
1682 }
1683
1684 //------------------------------Value-----------------------------------------
1685 const Type* LoadNode::Value(PhaseGVN* phase) const {
1686 // Either input is TOP ==> the result is TOP
1687 Node* mem = in(MemNode::Memory);
1688 const Type *t1 = phase->type(mem);
1689 if (t1 == Type::TOP) return Type::TOP;
1690 Node* adr = in(MemNode::Address);
1691 const TypePtr* tp = phase->type(adr)->isa_ptr();
1692 if (tp == NULL || tp->empty()) return Type::TOP;
1693 int off = tp->offset();
1694 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1695 Compile* C = phase->C;
1696
1697 // Try to guess loaded type from pointer type
1698 if (tp->isa_aryptr()) {
1699 const TypeAryPtr* ary = tp->is_aryptr();
1700 const Type* t = ary->elem();
1701
1702 // Determine whether the reference is beyond the header or not, by comparing
1703 // the offset against the offset of the start of the array's data.
1704 // Different array types begin at slightly different offsets (12 vs. 16).
1705 // We choose T_BYTE as an example base type that is least restrictive
1706 // as to alignment, which will therefore produce the smallest
1707 // possible base offset.
1708 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1709 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1710
1711 // Try to constant-fold a stable array element.
1712 if (FoldStableValues && !is_mismatched_access() && ary->is_stable() && ary->const_oop() != NULL) {
1713 // Make sure the reference is not into the header and the offset is constant
1714 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1715 const Type* con_type = fold_stable_ary_elem(ary, off, is_unsigned(), memory_type());
1716 if (con_type != NULL) {
1717 return con_type;
1718 }
1719 }
1720 }
1721
1722 // Don't do this for integer types. There is only potential profit if
1723 // the element type t is lower than _type; that is, for int types, if _type is
1724 // more restrictive than t. This only happens here if one is short and the other
1725 // char (both 16 bits), and in those cases we've made an intentional decision
1726 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1727 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1728 //
1729 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1730 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1731 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1732 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1733 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1734 // In fact, that could have been the original type of p1, and p1 could have
1735 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1736 // expression (LShiftL quux 3) independently optimized to the constant 8.
1737 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1738 && (_type->isa_vect() == NULL)
1739 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1740 // t might actually be lower than _type, if _type is a unique
1741 // concrete subclass of abstract class t.
1742 if (off_beyond_header) { // is the offset beyond the header?
1743 const Type* jt = t->join_speculative(_type);
1744 // In any case, do not allow the join, per se, to empty out the type.
1745 if (jt->empty() && !t->empty()) {
1746 // This can happen if a interface-typed array narrows to a class type.
1747 jt = _type;
1748 }
1749 #ifdef ASSERT
1750 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1751 // The pointers in the autobox arrays are always non-null
1752 Node* base = adr->in(AddPNode::Base);
1753 if ((base != NULL) && base->is_DecodeN()) {
1754 // Get LoadN node which loads IntegerCache.cache field
1755 base = base->in(1);
1756 }
1757 if ((base != NULL) && base->is_Con()) {
1758 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1759 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1760 // It could be narrow oop
1761 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1762 }
1763 }
1764 }
1765 #endif
1766 return jt;
1767 }
1768 }
1769 } else if (tp->base() == Type::InstPtr) {
1770 ciEnv* env = C->env();
1771 const TypeInstPtr* tinst = tp->is_instptr();
1772 ciKlass* klass = tinst->klass();
1773 assert( off != Type::OffsetBot ||
1774 // arrays can be cast to Objects
1775 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1776 // unsafe field access may not have a constant offset
1777 C->has_unsafe_access(),
1778 "Field accesses must be precise" );
1779 // For oop loads, we expect the _type to be precise.
1780 // Optimizations for constant objects
1781 ciObject* const_oop = tinst->const_oop();
1782 if (const_oop != NULL) {
1783 // For constant CallSites treat the target field as a compile time constant.
1784 if (const_oop->is_call_site()) {
1785 ciCallSite* call_site = const_oop->as_call_site();
1786 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1787 if (field != NULL && field->is_call_site_target()) {
1788 ciMethodHandle* target = call_site->get_target();
1789 if (target != NULL) { // just in case
1790 ciConstant constant(T_OBJECT, target);
1791 const Type* t;
1792 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1793 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1794 } else {
1795 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1796 }
1797 // Add a dependence for invalidation of the optimization.
1798 if (!call_site->is_constant_call_site()) {
1799 C->dependencies()->assert_call_site_target_value(call_site, target);
1800 }
1801 return t;
1802 }
1803 }
1804 }
1805 }
1806 } else if (tp->base() == Type::KlassPtr) {
1807 assert( off != Type::OffsetBot ||
1808 // arrays can be cast to Objects
1809 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1810 // also allow array-loading from the primary supertype
1811 // array during subtype checks
1812 Opcode() == Op_LoadKlass,
1813 "Field accesses must be precise" );
1814 // For klass/static loads, we expect the _type to be precise
1815 }
1816
1817 const TypeKlassPtr *tkls = tp->isa_klassptr();
1818 if (tkls != NULL && !StressReflectiveCode) {
1819 ciKlass* klass = tkls->klass();
1820 if (klass->is_loaded() && tkls->klass_is_exact()) {
1821 // We are loading a field from a Klass metaobject whose identity
1822 // is known at compile time (the type is "exact" or "precise").
1823 // Check for fields we know are maintained as constants by the VM.
1824 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1825 // The field is Klass::_super_check_offset. Return its (constant) value.
1826 // (Folds up type checking code.)
1827 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1828 return TypeInt::make(klass->super_check_offset());
1829 }
1830 // Compute index into primary_supers array
1831 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1832 // Check for overflowing; use unsigned compare to handle the negative case.
1833 if( depth < ciKlass::primary_super_limit() ) {
1834 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1835 // (Folds up type checking code.)
1836 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1837 ciKlass *ss = klass->super_of_depth(depth);
1838 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1839 }
1840 const Type* aift = load_array_final_field(tkls, klass);
1841 if (aift != NULL) return aift;
1842 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1843 // The field is Klass::_java_mirror. Return its (constant) value.
1844 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1845 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1846 return TypeInstPtr::make(klass->java_mirror());
1847 }
1848 }
1849
1850 // We can still check if we are loading from the primary_supers array at a
1851 // shallow enough depth. Even though the klass is not exact, entries less
1852 // than or equal to its super depth are correct.
1853 if (klass->is_loaded() ) {
1854 ciType *inner = klass;
1855 while( inner->is_obj_array_klass() )
1856 inner = inner->as_obj_array_klass()->base_element_type();
1857 if( inner->is_instance_klass() &&
1858 !inner->as_instance_klass()->flags().is_interface() ) {
1859 // Compute index into primary_supers array
1860 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1861 // Check for overflowing; use unsigned compare to handle the negative case.
1862 if( depth < ciKlass::primary_super_limit() &&
1863 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1864 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1865 // (Folds up type checking code.)
1866 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1867 ciKlass *ss = klass->super_of_depth(depth);
1868 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1869 }
1870 }
1871 }
1872
1873 // If the type is enough to determine that the thing is not an array,
1874 // we can give the layout_helper a positive interval type.
1875 // This will help short-circuit some reflective code.
1876 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1877 && !klass->is_array_klass() // not directly typed as an array
1878 && !klass->is_interface() // specifically not Serializable & Cloneable
1879 && !klass->is_java_lang_Object() // not the supertype of all T[]
1880 ) {
1881 // Note: When interfaces are reliable, we can narrow the interface
1882 // test to (klass != Serializable && klass != Cloneable).
1883 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1884 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1885 // The key property of this type is that it folds up tests
1886 // for array-ness, since it proves that the layout_helper is positive.
1887 // Thus, a generic value like the basic object layout helper works fine.
1888 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1889 }
1890 }
1891
1892 // If we are loading from a freshly-allocated object, produce a zero,
1893 // if the load is provably beyond the header of the object.
1894 // (Also allow a variable load from a fresh array to produce zero.)
1895 const TypeOopPtr *tinst = tp->isa_oopptr();
1896 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1897 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1898 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1899 Node* value = can_see_stored_value(mem,phase);
1900 if (value != NULL && value->is_Con()) {
1901 assert(value->bottom_type()->higher_equal(_type),"sanity");
1902 return value->bottom_type();
1903 }
1904 }
1905
1906 if (is_instance) {
1907 // If we have an instance type and our memory input is the
1908 // programs's initial memory state, there is no matching store,
1909 // so just return a zero of the appropriate type
1910 Node *mem = in(MemNode::Memory);
1911 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1912 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1913 return Type::get_zero_type(_type->basic_type());
1914 }
1915 }
1916 return _type;
1917 }
1918
1919 //------------------------------match_edge-------------------------------------
1920 // Do we Match on this edge index or not? Match only the address.
1921 uint LoadNode::match_edge(uint idx) const {
1922 return idx == MemNode::Address;
1923 }
1924
1925 //--------------------------LoadBNode::Ideal--------------------------------------
1926 //
1927 // If the previous store is to the same address as this load,
1928 // and the value stored was larger than a byte, replace this load
1929 // with the value stored truncated to a byte. If no truncation is
1930 // needed, the replacement is done in LoadNode::Identity().
1931 //
1932 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1933 Node* mem = in(MemNode::Memory);
1934 Node* value = can_see_stored_value(mem,phase);
1935 if( value && !phase->type(value)->higher_equal( _type ) ) {
1936 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1937 return new RShiftINode(result, phase->intcon(24));
1938 }
1939 // Identity call will handle the case where truncation is not needed.
1940 return LoadNode::Ideal(phase, can_reshape);
1941 }
1942
1943 const Type* LoadBNode::Value(PhaseGVN* phase) const {
1944 Node* mem = in(MemNode::Memory);
1945 Node* value = can_see_stored_value(mem,phase);
1946 if (value != NULL && value->is_Con() &&
1947 !value->bottom_type()->higher_equal(_type)) {
1948 // If the input to the store does not fit with the load's result type,
1949 // it must be truncated. We can't delay until Ideal call since
1950 // a singleton Value is needed for split_thru_phi optimization.
1951 int con = value->get_int();
1952 return TypeInt::make((con << 24) >> 24);
1953 }
1954 return LoadNode::Value(phase);
1955 }
1956
1957 //--------------------------LoadUBNode::Ideal-------------------------------------
1958 //
1959 // If the previous store is to the same address as this load,
1960 // and the value stored was larger than a byte, replace this load
1961 // with the value stored truncated to a byte. If no truncation is
1962 // needed, the replacement is done in LoadNode::Identity().
1963 //
1964 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1965 Node* mem = in(MemNode::Memory);
1966 Node* value = can_see_stored_value(mem, phase);
1967 if (value && !phase->type(value)->higher_equal(_type))
1968 return new AndINode(value, phase->intcon(0xFF));
1969 // Identity call will handle the case where truncation is not needed.
1970 return LoadNode::Ideal(phase, can_reshape);
1971 }
1972
1973 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
1974 Node* mem = in(MemNode::Memory);
1975 Node* value = can_see_stored_value(mem,phase);
1976 if (value != NULL && value->is_Con() &&
1977 !value->bottom_type()->higher_equal(_type)) {
1978 // If the input to the store does not fit with the load's result type,
1979 // it must be truncated. We can't delay until Ideal call since
1980 // a singleton Value is needed for split_thru_phi optimization.
1981 int con = value->get_int();
1982 return TypeInt::make(con & 0xFF);
1983 }
1984 return LoadNode::Value(phase);
1985 }
1986
1987 //--------------------------LoadUSNode::Ideal-------------------------------------
1988 //
1989 // If the previous store is to the same address as this load,
1990 // and the value stored was larger than a char, replace this load
1991 // with the value stored truncated to a char. If no truncation is
1992 // needed, the replacement is done in LoadNode::Identity().
1993 //
1994 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1995 Node* mem = in(MemNode::Memory);
1996 Node* value = can_see_stored_value(mem,phase);
1997 if( value && !phase->type(value)->higher_equal( _type ) )
1998 return new AndINode(value,phase->intcon(0xFFFF));
1999 // Identity call will handle the case where truncation is not needed.
2000 return LoadNode::Ideal(phase, can_reshape);
2001 }
2002
2003 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2004 Node* mem = in(MemNode::Memory);
2005 Node* value = can_see_stored_value(mem,phase);
2006 if (value != NULL && value->is_Con() &&
2007 !value->bottom_type()->higher_equal(_type)) {
2008 // If the input to the store does not fit with the load's result type,
2009 // it must be truncated. We can't delay until Ideal call since
2010 // a singleton Value is needed for split_thru_phi optimization.
2011 int con = value->get_int();
2012 return TypeInt::make(con & 0xFFFF);
2013 }
2014 return LoadNode::Value(phase);
2015 }
2016
2017 //--------------------------LoadSNode::Ideal--------------------------------------
2018 //
2019 // If the previous store is to the same address as this load,
2020 // and the value stored was larger than a short, replace this load
2021 // with the value stored truncated to a short. If no truncation is
2022 // needed, the replacement is done in LoadNode::Identity().
2023 //
2024 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2025 Node* mem = in(MemNode::Memory);
2026 Node* value = can_see_stored_value(mem,phase);
2027 if( value && !phase->type(value)->higher_equal( _type ) ) {
2028 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
2029 return new RShiftINode(result, phase->intcon(16));
2030 }
2031 // Identity call will handle the case where truncation is not needed.
2032 return LoadNode::Ideal(phase, can_reshape);
2033 }
2034
2035 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2036 Node* mem = in(MemNode::Memory);
2037 Node* value = can_see_stored_value(mem,phase);
2038 if (value != NULL && value->is_Con() &&
2039 !value->bottom_type()->higher_equal(_type)) {
2040 // If the input to the store does not fit with the load's result type,
2041 // it must be truncated. We can't delay until Ideal call since
2042 // a singleton Value is needed for split_thru_phi optimization.
2043 int con = value->get_int();
2044 return TypeInt::make((con << 16) >> 16);
2045 }
2046 return LoadNode::Value(phase);
2047 }
2048
2049 //=============================================================================
2050 //----------------------------LoadKlassNode::make------------------------------
2051 // Polymorphic factory method:
2052 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2053 // sanity check the alias category against the created node type
2054 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2055 assert(adr_type != NULL, "expecting TypeKlassPtr");
2056 #ifdef _LP64
2057 if (adr_type->is_ptr_to_narrowklass()) {
2058 assert(UseCompressedClassPointers, "no compressed klasses");
2059 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2060 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2061 }
2062 #endif
2063 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2064 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2065 }
2066
2067 //------------------------------Value------------------------------------------
2068 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2069 return klass_value_common(phase);
2070 }
2071
2072 // In most cases, LoadKlassNode does not have the control input set. If the control
2073 // input is set, it must not be removed (by LoadNode::Ideal()).
2074 bool LoadKlassNode::can_remove_control() const {
2075 return false;
2076 }
2077
2078 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2079 // Either input is TOP ==> the result is TOP
2080 const Type *t1 = phase->type( in(MemNode::Memory) );
2081 if (t1 == Type::TOP) return Type::TOP;
2082 Node *adr = in(MemNode::Address);
2083 const Type *t2 = phase->type( adr );
2084 if (t2 == Type::TOP) return Type::TOP;
2085 const TypePtr *tp = t2->is_ptr();
2086 if (TypePtr::above_centerline(tp->ptr()) ||
2087 tp->ptr() == TypePtr::Null) return Type::TOP;
2088
2089 // Return a more precise klass, if possible
2090 const TypeInstPtr *tinst = tp->isa_instptr();
2091 if (tinst != NULL) {
2092 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2093 int offset = tinst->offset();
2094 if (ik == phase->C->env()->Class_klass()
2095 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2096 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2097 // We are loading a special hidden field from a Class mirror object,
2098 // the field which points to the VM's Klass metaobject.
2099 ciType* t = tinst->java_mirror_type();
2100 // java_mirror_type returns non-null for compile-time Class constants.
2101 if (t != NULL) {
2102 // constant oop => constant klass
2103 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2104 if (t->is_void()) {
2105 // We cannot create a void array. Since void is a primitive type return null
2106 // klass. Users of this result need to do a null check on the returned klass.
2107 return TypePtr::NULL_PTR;
2108 }
2109 return TypeKlassPtr::make(ciArrayKlass::make(t));
2110 }
2111 if (!t->is_klass()) {
2112 // a primitive Class (e.g., int.class) has NULL for a klass field
2113 return TypePtr::NULL_PTR;
2114 }
2115 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2116 return TypeKlassPtr::make(t->as_klass());
2117 }
2118 // non-constant mirror, so we can't tell what's going on
2119 }
2120 if( !ik->is_loaded() )
2121 return _type; // Bail out if not loaded
2122 if (offset == oopDesc::klass_offset_in_bytes()) {
2123 if (tinst->klass_is_exact()) {
2124 return TypeKlassPtr::make(ik);
2125 }
2126 // See if we can become precise: no subklasses and no interface
2127 // (Note: We need to support verified interfaces.)
2128 if (!ik->is_interface() && !ik->has_subklass()) {
2129 //assert(!UseExactTypes, "this code should be useless with exact types");
2130 // Add a dependence; if any subclass added we need to recompile
2131 if (!ik->is_final()) {
2132 // %%% should use stronger assert_unique_concrete_subtype instead
2133 phase->C->dependencies()->assert_leaf_type(ik);
2134 }
2135 // Return precise klass
2136 return TypeKlassPtr::make(ik);
2137 }
2138
2139 // Return root of possible klass
2140 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2141 }
2142 }
2143
2144 // Check for loading klass from an array
2145 const TypeAryPtr *tary = tp->isa_aryptr();
2146 if( tary != NULL ) {
2147 ciKlass *tary_klass = tary->klass();
2148 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2149 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2150 if (tary->klass_is_exact()) {
2151 return TypeKlassPtr::make(tary_klass);
2152 }
2153 ciArrayKlass *ak = tary->klass()->as_array_klass();
2154 // If the klass is an object array, we defer the question to the
2155 // array component klass.
2156 if( ak->is_obj_array_klass() ) {
2157 assert( ak->is_loaded(), "" );
2158 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2159 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2160 ciInstanceKlass* ik = base_k->as_instance_klass();
2161 // See if we can become precise: no subklasses and no interface
2162 if (!ik->is_interface() && !ik->has_subklass()) {
2163 //assert(!UseExactTypes, "this code should be useless with exact types");
2164 // Add a dependence; if any subclass added we need to recompile
2165 if (!ik->is_final()) {
2166 phase->C->dependencies()->assert_leaf_type(ik);
2167 }
2168 // Return precise array klass
2169 return TypeKlassPtr::make(ak);
2170 }
2171 }
2172 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2173 } else { // Found a type-array?
2174 //assert(!UseExactTypes, "this code should be useless with exact types");
2175 assert( ak->is_type_array_klass(), "" );
2176 return TypeKlassPtr::make(ak); // These are always precise
2177 }
2178 }
2179 }
2180
2181 // Check for loading klass from an array klass
2182 const TypeKlassPtr *tkls = tp->isa_klassptr();
2183 if (tkls != NULL && !StressReflectiveCode) {
2184 ciKlass* klass = tkls->klass();
2185 if( !klass->is_loaded() )
2186 return _type; // Bail out if not loaded
2187 if( klass->is_obj_array_klass() &&
2188 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2189 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2190 // // Always returning precise element type is incorrect,
2191 // // e.g., element type could be object and array may contain strings
2192 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2193
2194 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2195 // according to the element type's subclassing.
2196 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2197 }
2198 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2199 tkls->offset() == in_bytes(Klass::super_offset())) {
2200 ciKlass* sup = klass->as_instance_klass()->super();
2201 // The field is Klass::_super. Return its (constant) value.
2202 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2203 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2204 }
2205 }
2206
2207 // Bailout case
2208 return LoadNode::Value(phase);
2209 }
2210
2211 //------------------------------Identity---------------------------------------
2212 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2213 // Also feed through the klass in Allocate(...klass...)._klass.
2214 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2215 return klass_identity_common(phase);
2216 }
2217
2218 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2219 Node* x = LoadNode::Identity(phase);
2220 if (x != this) return x;
2221
2222 // Take apart the address into an oop and and offset.
2223 // Return 'this' if we cannot.
2224 Node* adr = in(MemNode::Address);
2225 intptr_t offset = 0;
2226 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2227 if (base == NULL) return this;
2228 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2229 if (toop == NULL) return this;
2230
2231 // We can fetch the klass directly through an AllocateNode.
2232 // This works even if the klass is not constant (clone or newArray).
2233 if (offset == oopDesc::klass_offset_in_bytes()) {
2234 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2235 if (allocated_klass != NULL) {
2236 return allocated_klass;
2237 }
2238 }
2239
2240 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2241 // See inline_native_Class_query for occurrences of these patterns.
2242 // Java Example: x.getClass().isAssignableFrom(y)
2243 //
2244 // This improves reflective code, often making the Class
2245 // mirror go completely dead. (Current exception: Class
2246 // mirrors may appear in debug info, but we could clean them out by
2247 // introducing a new debug info operator for Klass*.java_mirror).
2248 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2249 && offset == java_lang_Class::klass_offset_in_bytes()) {
2250 // We are loading a special hidden field from a Class mirror,
2251 // the field which points to its Klass or ArrayKlass metaobject.
2252 if (base->is_Load()) {
2253 Node* adr2 = base->in(MemNode::Address);
2254 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2255 if (tkls != NULL && !tkls->empty()
2256 && (tkls->klass()->is_instance_klass() ||
2257 tkls->klass()->is_array_klass())
2258 && adr2->is_AddP()
2259 ) {
2260 int mirror_field = in_bytes(Klass::java_mirror_offset());
2261 if (tkls->offset() == mirror_field) {
2262 return adr2->in(AddPNode::Base);
2263 }
2264 }
2265 }
2266 }
2267
2268 return this;
2269 }
2270
2271
2272 //------------------------------Value------------------------------------------
2273 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2274 const Type *t = klass_value_common(phase);
2275 if (t == Type::TOP)
2276 return t;
2277
2278 return t->make_narrowklass();
2279 }
2280
2281 //------------------------------Identity---------------------------------------
2282 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2283 // Also feed through the klass in Allocate(...klass...)._klass.
2284 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2285 Node *x = klass_identity_common(phase);
2286
2287 const Type *t = phase->type( x );
2288 if( t == Type::TOP ) return x;
2289 if( t->isa_narrowklass()) return x;
2290 assert (!t->isa_narrowoop(), "no narrow oop here");
2291
2292 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2293 }
2294
2295 //------------------------------Value-----------------------------------------
2296 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2297 // Either input is TOP ==> the result is TOP
2298 const Type *t1 = phase->type( in(MemNode::Memory) );
2299 if( t1 == Type::TOP ) return Type::TOP;
2300 Node *adr = in(MemNode::Address);
2301 const Type *t2 = phase->type( adr );
2302 if( t2 == Type::TOP ) return Type::TOP;
2303 const TypePtr *tp = t2->is_ptr();
2304 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2305 const TypeAryPtr *tap = tp->isa_aryptr();
2306 if( !tap ) return _type;
2307 return tap->size();
2308 }
2309
2310 //-------------------------------Ideal---------------------------------------
2311 // Feed through the length in AllocateArray(...length...)._length.
2312 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2313 Node* p = MemNode::Ideal_common(phase, can_reshape);
2314 if (p) return (p == NodeSentinel) ? NULL : p;
2315
2316 // Take apart the address into an oop and and offset.
2317 // Return 'this' if we cannot.
2318 Node* adr = in(MemNode::Address);
2319 intptr_t offset = 0;
2320 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2321 if (base == NULL) return NULL;
2322 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2323 if (tary == NULL) return NULL;
2324
2325 // We can fetch the length directly through an AllocateArrayNode.
2326 // This works even if the length is not constant (clone or newArray).
2327 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2328 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2329 if (alloc != NULL) {
2330 Node* allocated_length = alloc->Ideal_length();
2331 Node* len = alloc->make_ideal_length(tary, phase);
2332 if (allocated_length != len) {
2333 // New CastII improves on this.
2334 return len;
2335 }
2336 }
2337 }
2338
2339 return NULL;
2340 }
2341
2342 //------------------------------Identity---------------------------------------
2343 // Feed through the length in AllocateArray(...length...)._length.
2344 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2345 Node* x = LoadINode::Identity(phase);
2346 if (x != this) return x;
2347
2348 // Take apart the address into an oop and and offset.
2349 // Return 'this' if we cannot.
2350 Node* adr = in(MemNode::Address);
2351 intptr_t offset = 0;
2352 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2353 if (base == NULL) return this;
2354 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2355 if (tary == NULL) return this;
2356
2357 // We can fetch the length directly through an AllocateArrayNode.
2358 // This works even if the length is not constant (clone or newArray).
2359 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2360 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2361 if (alloc != NULL) {
2362 Node* allocated_length = alloc->Ideal_length();
2363 // Do not allow make_ideal_length to allocate a CastII node.
2364 Node* len = alloc->make_ideal_length(tary, phase, false);
2365 if (allocated_length == len) {
2366 // Return allocated_length only if it would not be improved by a CastII.
2367 return allocated_length;
2368 }
2369 }
2370 }
2371
2372 return this;
2373
2374 }
2375
2376 //=============================================================================
2377 //---------------------------StoreNode::make-----------------------------------
2378 // Polymorphic factory method:
2379 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2380 assert((mo == unordered || mo == release), "unexpected");
2381 Compile* C = gvn.C;
2382 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2383 ctl != NULL, "raw memory operations should have control edge");
2384
2385 switch (bt) {
2386 case T_BOOLEAN:
2387 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2388 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2389 case T_CHAR:
2390 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2391 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2392 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2393 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2394 case T_METADATA:
2395 case T_ADDRESS:
2396 case T_OBJECT:
2397 #ifdef _LP64
2398 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2399 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2400 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2401 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2402 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2403 adr->bottom_type()->isa_rawptr())) {
2404 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2405 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2406 }
2407 #endif
2408 {
2409 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2410 }
2411 }
2412 ShouldNotReachHere();
2413 return (StoreNode*)NULL;
2414 }
2415
2416 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2417 bool require_atomic = true;
2418 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2419 }
2420
2421 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2422 bool require_atomic = true;
2423 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2424 }
2425
2426
2427 //--------------------------bottom_type----------------------------------------
2428 const Type *StoreNode::bottom_type() const {
2429 return Type::MEMORY;
2430 }
2431
2432 //------------------------------hash-------------------------------------------
2433 uint StoreNode::hash() const {
2434 // unroll addition of interesting fields
2435 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2436
2437 // Since they are not commoned, do not hash them:
2438 return NO_HASH;
2439 }
2440
2441 //------------------------------Ideal------------------------------------------
2442 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2443 // When a store immediately follows a relevant allocation/initialization,
2444 // try to capture it into the initialization, or hoist it above.
2445 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2446 Node* p = MemNode::Ideal_common(phase, can_reshape);
2447 if (p) return (p == NodeSentinel) ? NULL : p;
2448
2449 Node* mem = in(MemNode::Memory);
2450 Node* address = in(MemNode::Address);
2451 // Back-to-back stores to same address? Fold em up. Generally
2452 // unsafe if I have intervening uses... Also disallowed for StoreCM
2453 // since they must follow each StoreP operation. Redundant StoreCMs
2454 // are eliminated just before matching in final_graph_reshape.
2455 {
2456 Node* st = mem;
2457 // If Store 'st' has more than one use, we cannot fold 'st' away.
2458 // For example, 'st' might be the final state at a conditional
2459 // return. Or, 'st' might be used by some node which is live at
2460 // the same time 'st' is live, which might be unschedulable. So,
2461 // require exactly ONE user until such time as we clone 'mem' for
2462 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2463 // true).
2464 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2465 // Looking at a dead closed cycle of memory?
2466 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2467 assert(Opcode() == st->Opcode() ||
2468 st->Opcode() == Op_StoreVector ||
2469 Opcode() == Op_StoreVector ||
2470 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2471 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2472 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2473 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2474
2475 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2476 st->as_Store()->memory_size() <= this->memory_size()) {
2477 Node* use = st->raw_out(0);
2478 phase->igvn_rehash_node_delayed(use);
2479 if (can_reshape) {
2480 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase->is_IterGVN());
2481 } else {
2482 // It's OK to do this in the parser, since DU info is always accurate,
2483 // and the parser always refers to nodes via SafePointNode maps.
2484 use->set_req(MemNode::Memory, st->in(MemNode::Memory));
2485 }
2486 return this;
2487 }
2488 st = st->in(MemNode::Memory);
2489 }
2490 }
2491
2492
2493 // Capture an unaliased, unconditional, simple store into an initializer.
2494 // Or, if it is independent of the allocation, hoist it above the allocation.
2495 if (ReduceFieldZeroing && /*can_reshape &&*/
2496 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2497 InitializeNode* init = mem->in(0)->as_Initialize();
2498 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2499 if (offset > 0) {
2500 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2501 // If the InitializeNode captured me, it made a raw copy of me,
2502 // and I need to disappear.
2503 if (moved != NULL) {
2504 // %%% hack to ensure that Ideal returns a new node:
2505 mem = MergeMemNode::make(mem);
2506 return mem; // fold me away
2507 }
2508 }
2509 }
2510
2511 return NULL; // No further progress
2512 }
2513
2514 //------------------------------Value-----------------------------------------
2515 const Type* StoreNode::Value(PhaseGVN* phase) const {
2516 // Either input is TOP ==> the result is TOP
2517 const Type *t1 = phase->type( in(MemNode::Memory) );
2518 if( t1 == Type::TOP ) return Type::TOP;
2519 const Type *t2 = phase->type( in(MemNode::Address) );
2520 if( t2 == Type::TOP ) return Type::TOP;
2521 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2522 if( t3 == Type::TOP ) return Type::TOP;
2523 return Type::MEMORY;
2524 }
2525
2526 //------------------------------Identity---------------------------------------
2527 // Remove redundant stores:
2528 // Store(m, p, Load(m, p)) changes to m.
2529 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2530 Node* StoreNode::Identity(PhaseGVN* phase) {
2531 Node* mem = in(MemNode::Memory);
2532 Node* adr = in(MemNode::Address);
2533 Node* val = in(MemNode::ValueIn);
2534
2535 // Load then Store? Then the Store is useless
2536 if (val->is_Load() &&
2537 val->in(MemNode::Address)->eqv_uncast(adr) &&
2538 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2539 val->as_Load()->store_Opcode() == Opcode()) {
2540 return mem;
2541 }
2542
2543 // Two stores in a row of the same value?
2544 if (mem->is_Store() &&
2545 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2546 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2547 mem->Opcode() == Opcode()) {
2548 return mem;
2549 }
2550
2551 // Store of zero anywhere into a freshly-allocated object?
2552 // Then the store is useless.
2553 // (It must already have been captured by the InitializeNode.)
2554 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2555 // a newly allocated object is already all-zeroes everywhere
2556 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2557 return mem;
2558 }
2559
2560 // the store may also apply to zero-bits in an earlier object
2561 Node* prev_mem = find_previous_store(phase);
2562 // Steps (a), (b): Walk past independent stores to find an exact match.
2563 if (prev_mem != NULL) {
2564 Node* prev_val = can_see_stored_value(prev_mem, phase);
2565 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2566 // prev_val and val might differ by a cast; it would be good
2567 // to keep the more informative of the two.
2568 return mem;
2569 }
2570 }
2571 }
2572
2573 return this;
2574 }
2575
2576 //------------------------------match_edge-------------------------------------
2577 // Do we Match on this edge index or not? Match only memory & value
2578 uint StoreNode::match_edge(uint idx) const {
2579 return idx == MemNode::Address || idx == MemNode::ValueIn;
2580 }
2581
2582 //------------------------------cmp--------------------------------------------
2583 // Do not common stores up together. They generally have to be split
2584 // back up anyways, so do not bother.
2585 uint StoreNode::cmp( const Node &n ) const {
2586 return (&n == this); // Always fail except on self
2587 }
2588
2589 //------------------------------Ideal_masked_input-----------------------------
2590 // Check for a useless mask before a partial-word store
2591 // (StoreB ... (AndI valIn conIa) )
2592 // If (conIa & mask == mask) this simplifies to
2593 // (StoreB ... (valIn) )
2594 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2595 Node *val = in(MemNode::ValueIn);
2596 if( val->Opcode() == Op_AndI ) {
2597 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2598 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2599 set_req(MemNode::ValueIn, val->in(1));
2600 return this;
2601 }
2602 }
2603 return NULL;
2604 }
2605
2606
2607 //------------------------------Ideal_sign_extended_input----------------------
2608 // Check for useless sign-extension before a partial-word store
2609 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2610 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2611 // (StoreB ... (valIn) )
2612 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2613 Node *val = in(MemNode::ValueIn);
2614 if( val->Opcode() == Op_RShiftI ) {
2615 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2616 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2617 Node *shl = val->in(1);
2618 if( shl->Opcode() == Op_LShiftI ) {
2619 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2620 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2621 set_req(MemNode::ValueIn, shl->in(1));
2622 return this;
2623 }
2624 }
2625 }
2626 }
2627 return NULL;
2628 }
2629
2630 //------------------------------value_never_loaded-----------------------------------
2631 // Determine whether there are any possible loads of the value stored.
2632 // For simplicity, we actually check if there are any loads from the
2633 // address stored to, not just for loads of the value stored by this node.
2634 //
2635 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2636 Node *adr = in(Address);
2637 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2638 if (adr_oop == NULL)
2639 return false;
2640 if (!adr_oop->is_known_instance_field())
2641 return false; // if not a distinct instance, there may be aliases of the address
2642 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2643 Node *use = adr->fast_out(i);
2644 if (use->is_Load() || use->is_LoadStore()) {
2645 return false;
2646 }
2647 }
2648 return true;
2649 }
2650
2651 //=============================================================================
2652 //------------------------------Ideal------------------------------------------
2653 // If the store is from an AND mask that leaves the low bits untouched, then
2654 // we can skip the AND operation. If the store is from a sign-extension
2655 // (a left shift, then right shift) we can skip both.
2656 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2657 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2658 if( progress != NULL ) return progress;
2659
2660 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2661 if( progress != NULL ) return progress;
2662
2663 // Finally check the default case
2664 return StoreNode::Ideal(phase, can_reshape);
2665 }
2666
2667 //=============================================================================
2668 //------------------------------Ideal------------------------------------------
2669 // If the store is from an AND mask that leaves the low bits untouched, then
2670 // we can skip the AND operation
2671 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2672 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2673 if( progress != NULL ) return progress;
2674
2675 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2676 if( progress != NULL ) return progress;
2677
2678 // Finally check the default case
2679 return StoreNode::Ideal(phase, can_reshape);
2680 }
2681
2682 //=============================================================================
2683 //------------------------------Identity---------------------------------------
2684 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2685 // No need to card mark when storing a null ptr
2686 Node* my_store = in(MemNode::OopStore);
2687 if (my_store->is_Store()) {
2688 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2689 if( t1 == TypePtr::NULL_PTR ) {
2690 return in(MemNode::Memory);
2691 }
2692 }
2693 return this;
2694 }
2695
2696 //=============================================================================
2697 //------------------------------Ideal---------------------------------------
2698 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2699 Node* progress = StoreNode::Ideal(phase, can_reshape);
2700 if (progress != NULL) return progress;
2701
2702 Node* my_store = in(MemNode::OopStore);
2703 if (my_store->is_MergeMem()) {
2704 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2705 set_req(MemNode::OopStore, mem);
2706 return this;
2707 }
2708
2709 return NULL;
2710 }
2711
2712 //------------------------------Value-----------------------------------------
2713 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2714 // Either input is TOP ==> the result is TOP
2715 const Type *t = phase->type( in(MemNode::Memory) );
2716 if( t == Type::TOP ) return Type::TOP;
2717 t = phase->type( in(MemNode::Address) );
2718 if( t == Type::TOP ) return Type::TOP;
2719 t = phase->type( in(MemNode::ValueIn) );
2720 if( t == Type::TOP ) return Type::TOP;
2721 // If extra input is TOP ==> the result is TOP
2722 t = phase->type( in(MemNode::OopStore) );
2723 if( t == Type::TOP ) return Type::TOP;
2724
2725 return StoreNode::Value( phase );
2726 }
2727
2728
2729 //=============================================================================
2730 //----------------------------------SCMemProjNode------------------------------
2731 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
2732 {
2733 return bottom_type();
2734 }
2735
2736 //=============================================================================
2737 //----------------------------------LoadStoreNode------------------------------
2738 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2739 : Node(required),
2740 _type(rt),
2741 _adr_type(at)
2742 {
2743 init_req(MemNode::Control, c );
2744 init_req(MemNode::Memory , mem);
2745 init_req(MemNode::Address, adr);
2746 init_req(MemNode::ValueIn, val);
2747 init_class_id(Class_LoadStore);
2748 }
2749
2750 uint LoadStoreNode::ideal_reg() const {
2751 return _type->ideal_reg();
2752 }
2753
2754 bool LoadStoreNode::result_not_used() const {
2755 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2756 Node *x = fast_out(i);
2757 if (x->Opcode() == Op_SCMemProj) continue;
2758 return false;
2759 }
2760 return true;
2761 }
2762
2763 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2764
2765 //=============================================================================
2766 //----------------------------------LoadStoreConditionalNode--------------------
2767 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2768 init_req(ExpectedIn, ex );
2769 }
2770
2771 //=============================================================================
2772 //-------------------------------adr_type--------------------------------------
2773 const TypePtr* ClearArrayNode::adr_type() const {
2774 Node *adr = in(3);
2775 if (adr == NULL) return NULL; // node is dead
2776 return MemNode::calculate_adr_type(adr->bottom_type());
2777 }
2778
2779 //------------------------------match_edge-------------------------------------
2780 // Do we Match on this edge index or not? Do not match memory
2781 uint ClearArrayNode::match_edge(uint idx) const {
2782 return idx > 1;
2783 }
2784
2785 //------------------------------Identity---------------------------------------
2786 // Clearing a zero length array does nothing
2787 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
2788 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2789 }
2790
2791 //------------------------------Idealize---------------------------------------
2792 // Clearing a short array is faster with stores
2793 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2794 // Already know this is a large node, do not try to ideal it
2795 if (_is_large) return NULL;
2796
2797 const int unit = BytesPerLong;
2798 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2799 if (!t) return NULL;
2800 if (!t->is_con()) return NULL;
2801 intptr_t raw_count = t->get_con();
2802 intptr_t size = raw_count;
2803 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2804 // Clearing nothing uses the Identity call.
2805 // Negative clears are possible on dead ClearArrays
2806 // (see jck test stmt114.stmt11402.val).
2807 if (size <= 0 || size % unit != 0) return NULL;
2808 intptr_t count = size / unit;
2809 // Length too long; communicate this to matchers and assemblers.
2810 // Assemblers are responsible to produce fast hardware clears for it.
2811 if (size > InitArrayShortSize) {
2812 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
2813 }
2814 Node *mem = in(1);
2815 if( phase->type(mem)==Type::TOP ) return NULL;
2816 Node *adr = in(3);
2817 const Type* at = phase->type(adr);
2818 if( at==Type::TOP ) return NULL;
2819 const TypePtr* atp = at->isa_ptr();
2820 // adjust atp to be the correct array element address type
2821 if (atp == NULL) atp = TypePtr::BOTTOM;
2822 else atp = atp->add_offset(Type::OffsetBot);
2823 // Get base for derived pointer purposes
2824 if( adr->Opcode() != Op_AddP ) Unimplemented();
2825 Node *base = adr->in(1);
2826
2827 Node *zero = phase->makecon(TypeLong::ZERO);
2828 Node *off = phase->MakeConX(BytesPerLong);
2829 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2830 count--;
2831 while( count-- ) {
2832 mem = phase->transform(mem);
2833 adr = phase->transform(new AddPNode(base,adr,off));
2834 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2835 }
2836 return mem;
2837 }
2838
2839 //----------------------------step_through----------------------------------
2840 // Return allocation input memory edge if it is different instance
2841 // or itself if it is the one we are looking for.
2842 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2843 Node* n = *np;
2844 assert(n->is_ClearArray(), "sanity");
2845 intptr_t offset;
2846 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2847 // This method is called only before Allocate nodes are expanded
2848 // during macro nodes expansion. Before that ClearArray nodes are
2849 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2850 // Allocate nodes are expanded) which follows allocations.
2851 assert(alloc != NULL, "should have allocation");
2852 if (alloc->_idx == instance_id) {
2853 // Can not bypass initialization of the instance we are looking for.
2854 return false;
2855 }
2856 // Otherwise skip it.
2857 InitializeNode* init = alloc->initialization();
2858 if (init != NULL)
2859 *np = init->in(TypeFunc::Memory);
2860 else
2861 *np = alloc->in(TypeFunc::Memory);
2862 return true;
2863 }
2864
2865 //----------------------------clear_memory-------------------------------------
2866 // Generate code to initialize object storage to zero.
2867 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2868 intptr_t start_offset,
2869 Node* end_offset,
2870 PhaseGVN* phase) {
2871 intptr_t offset = start_offset;
2872
2873 int unit = BytesPerLong;
2874 if ((offset % unit) != 0) {
2875 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2876 adr = phase->transform(adr);
2877 const TypePtr* atp = TypeRawPtr::BOTTOM;
2878 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2879 mem = phase->transform(mem);
2880 offset += BytesPerInt;
2881 }
2882 assert((offset % unit) == 0, "");
2883
2884 // Initialize the remaining stuff, if any, with a ClearArray.
2885 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2886 }
2887
2888 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2889 Node* start_offset,
2890 Node* end_offset,
2891 PhaseGVN* phase) {
2892 if (start_offset == end_offset) {
2893 // nothing to do
2894 return mem;
2895 }
2896
2897 int unit = BytesPerLong;
2898 Node* zbase = start_offset;
2899 Node* zend = end_offset;
2900
2901 // Scale to the unit required by the CPU:
2902 if (!Matcher::init_array_count_is_in_bytes) {
2903 Node* shift = phase->intcon(exact_log2(unit));
2904 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2905 zend = phase->transform(new URShiftXNode(zend, shift) );
2906 }
2907
2908 // Bulk clear double-words
2909 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2910 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2911 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
2912 return phase->transform(mem);
2913 }
2914
2915 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2916 intptr_t start_offset,
2917 intptr_t end_offset,
2918 PhaseGVN* phase) {
2919 if (start_offset == end_offset) {
2920 // nothing to do
2921 return mem;
2922 }
2923
2924 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2925 intptr_t done_offset = end_offset;
2926 if ((done_offset % BytesPerLong) != 0) {
2927 done_offset -= BytesPerInt;
2928 }
2929 if (done_offset > start_offset) {
2930 mem = clear_memory(ctl, mem, dest,
2931 start_offset, phase->MakeConX(done_offset), phase);
2932 }
2933 if (done_offset < end_offset) { // emit the final 32-bit store
2934 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2935 adr = phase->transform(adr);
2936 const TypePtr* atp = TypeRawPtr::BOTTOM;
2937 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2938 mem = phase->transform(mem);
2939 done_offset += BytesPerInt;
2940 }
2941 assert(done_offset == end_offset, "");
2942 return mem;
2943 }
2944
2945 //=============================================================================
2946 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2947 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2948 _adr_type(C->get_adr_type(alias_idx))
2949 {
2950 init_class_id(Class_MemBar);
2951 Node* top = C->top();
2952 init_req(TypeFunc::I_O,top);
2953 init_req(TypeFunc::FramePtr,top);
2954 init_req(TypeFunc::ReturnAdr,top);
2955 if (precedent != NULL)
2956 init_req(TypeFunc::Parms, precedent);
2957 }
2958
2959 //------------------------------cmp--------------------------------------------
2960 uint MemBarNode::hash() const { return NO_HASH; }
2961 uint MemBarNode::cmp( const Node &n ) const {
2962 return (&n == this); // Always fail except on self
2963 }
2964
2965 //------------------------------make-------------------------------------------
2966 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2967 switch (opcode) {
2968 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2969 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2970 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2971 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2972 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2973 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2974 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2975 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2976 case Op_Initialize: return new InitializeNode(C, atp, pn);
2977 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2978 default: ShouldNotReachHere(); return NULL;
2979 }
2980 }
2981
2982 //------------------------------Ideal------------------------------------------
2983 // Return a node which is more "ideal" than the current node. Strip out
2984 // control copies
2985 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2986 if (remove_dead_region(phase, can_reshape)) return this;
2987 // Don't bother trying to transform a dead node
2988 if (in(0) && in(0)->is_top()) {
2989 return NULL;
2990 }
2991
2992 bool progress = false;
2993 // Eliminate volatile MemBars for scalar replaced objects.
2994 if (can_reshape && req() == (Precedent+1)) {
2995 bool eliminate = false;
2996 int opc = Opcode();
2997 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2998 // Volatile field loads and stores.
2999 Node* my_mem = in(MemBarNode::Precedent);
3000 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3001 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3002 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3003 // replace this Precedent (decodeN) with the Load instead.
3004 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3005 Node* load_node = my_mem->in(1);
3006 set_req(MemBarNode::Precedent, load_node);
3007 phase->is_IterGVN()->_worklist.push(my_mem);
3008 my_mem = load_node;
3009 } else {
3010 assert(my_mem->unique_out() == this, "sanity");
3011 del_req(Precedent);
3012 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3013 my_mem = NULL;
3014 }
3015 progress = true;
3016 }
3017 if (my_mem != NULL && my_mem->is_Mem()) {
3018 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3019 // Check for scalar replaced object reference.
3020 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3021 t_oop->offset() != Type::OffsetBot &&
3022 t_oop->offset() != Type::OffsetTop) {
3023 eliminate = true;
3024 }
3025 }
3026 } else if (opc == Op_MemBarRelease) {
3027 // Final field stores.
3028 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3029 if ((alloc != NULL) && alloc->is_Allocate() &&
3030 alloc->as_Allocate()->does_not_escape_thread()) {
3031 // The allocated object does not escape.
3032 eliminate = true;
3033 }
3034 }
3035 if (eliminate) {
3036 // Replace MemBar projections by its inputs.
3037 PhaseIterGVN* igvn = phase->is_IterGVN();
3038 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3039 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3040 // Must return either the original node (now dead) or a new node
3041 // (Do not return a top here, since that would break the uniqueness of top.)
3042 return new ConINode(TypeInt::ZERO);
3043 }
3044 }
3045 return progress ? this : NULL;
3046 }
3047
3048 //------------------------------Value------------------------------------------
3049 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3050 if( !in(0) ) return Type::TOP;
3051 if( phase->type(in(0)) == Type::TOP )
3052 return Type::TOP;
3053 return TypeTuple::MEMBAR;
3054 }
3055
3056 //------------------------------match------------------------------------------
3057 // Construct projections for memory.
3058 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3059 switch (proj->_con) {
3060 case TypeFunc::Control:
3061 case TypeFunc::Memory:
3062 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3063 }
3064 ShouldNotReachHere();
3065 return NULL;
3066 }
3067
3068 //===========================InitializeNode====================================
3069 // SUMMARY:
3070 // This node acts as a memory barrier on raw memory, after some raw stores.
3071 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3072 // The Initialize can 'capture' suitably constrained stores as raw inits.
3073 // It can coalesce related raw stores into larger units (called 'tiles').
3074 // It can avoid zeroing new storage for memory units which have raw inits.
3075 // At macro-expansion, it is marked 'complete', and does not optimize further.
3076 //
3077 // EXAMPLE:
3078 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3079 // ctl = incoming control; mem* = incoming memory
3080 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3081 // First allocate uninitialized memory and fill in the header:
3082 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3083 // ctl := alloc.Control; mem* := alloc.Memory*
3084 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3085 // Then initialize to zero the non-header parts of the raw memory block:
3086 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3087 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3088 // After the initialize node executes, the object is ready for service:
3089 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3090 // Suppose its body is immediately initialized as {1,2}:
3091 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3092 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3093 // mem.SLICE(#short[*]) := store2
3094 //
3095 // DETAILS:
3096 // An InitializeNode collects and isolates object initialization after
3097 // an AllocateNode and before the next possible safepoint. As a
3098 // memory barrier (MemBarNode), it keeps critical stores from drifting
3099 // down past any safepoint or any publication of the allocation.
3100 // Before this barrier, a newly-allocated object may have uninitialized bits.
3101 // After this barrier, it may be treated as a real oop, and GC is allowed.
3102 //
3103 // The semantics of the InitializeNode include an implicit zeroing of
3104 // the new object from object header to the end of the object.
3105 // (The object header and end are determined by the AllocateNode.)
3106 //
3107 // Certain stores may be added as direct inputs to the InitializeNode.
3108 // These stores must update raw memory, and they must be to addresses
3109 // derived from the raw address produced by AllocateNode, and with
3110 // a constant offset. They must be ordered by increasing offset.
3111 // The first one is at in(RawStores), the last at in(req()-1).
3112 // Unlike most memory operations, they are not linked in a chain,
3113 // but are displayed in parallel as users of the rawmem output of
3114 // the allocation.
3115 //
3116 // (See comments in InitializeNode::capture_store, which continue
3117 // the example given above.)
3118 //
3119 // When the associated Allocate is macro-expanded, the InitializeNode
3120 // may be rewritten to optimize collected stores. A ClearArrayNode
3121 // may also be created at that point to represent any required zeroing.
3122 // The InitializeNode is then marked 'complete', prohibiting further
3123 // capturing of nearby memory operations.
3124 //
3125 // During macro-expansion, all captured initializations which store
3126 // constant values of 32 bits or smaller are coalesced (if advantageous)
3127 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3128 // initialized in fewer memory operations. Memory words which are
3129 // covered by neither tiles nor non-constant stores are pre-zeroed
3130 // by explicit stores of zero. (The code shape happens to do all
3131 // zeroing first, then all other stores, with both sequences occurring
3132 // in order of ascending offsets.)
3133 //
3134 // Alternatively, code may be inserted between an AllocateNode and its
3135 // InitializeNode, to perform arbitrary initialization of the new object.
3136 // E.g., the object copying intrinsics insert complex data transfers here.
3137 // The initialization must then be marked as 'complete' disable the
3138 // built-in zeroing semantics and the collection of initializing stores.
3139 //
3140 // While an InitializeNode is incomplete, reads from the memory state
3141 // produced by it are optimizable if they match the control edge and
3142 // new oop address associated with the allocation/initialization.
3143 // They return a stored value (if the offset matches) or else zero.
3144 // A write to the memory state, if it matches control and address,
3145 // and if it is to a constant offset, may be 'captured' by the
3146 // InitializeNode. It is cloned as a raw memory operation and rewired
3147 // inside the initialization, to the raw oop produced by the allocation.
3148 // Operations on addresses which are provably distinct (e.g., to
3149 // other AllocateNodes) are allowed to bypass the initialization.
3150 //
3151 // The effect of all this is to consolidate object initialization
3152 // (both arrays and non-arrays, both piecewise and bulk) into a
3153 // single location, where it can be optimized as a unit.
3154 //
3155 // Only stores with an offset less than TrackedInitializationLimit words
3156 // will be considered for capture by an InitializeNode. This puts a
3157 // reasonable limit on the complexity of optimized initializations.
3158
3159 //---------------------------InitializeNode------------------------------------
3160 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3161 : _is_complete(Incomplete), _does_not_escape(false),
3162 MemBarNode(C, adr_type, rawoop)
3163 {
3164 init_class_id(Class_Initialize);
3165
3166 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3167 assert(in(RawAddress) == rawoop, "proper init");
3168 // Note: allocation() can be NULL, for secondary initialization barriers
3169 }
3170
3171 // Since this node is not matched, it will be processed by the
3172 // register allocator. Declare that there are no constraints
3173 // on the allocation of the RawAddress edge.
3174 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3175 // This edge should be set to top, by the set_complete. But be conservative.
3176 if (idx == InitializeNode::RawAddress)
3177 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3178 return RegMask::Empty;
3179 }
3180
3181 Node* InitializeNode::memory(uint alias_idx) {
3182 Node* mem = in(Memory);
3183 if (mem->is_MergeMem()) {
3184 return mem->as_MergeMem()->memory_at(alias_idx);
3185 } else {
3186 // incoming raw memory is not split
3187 return mem;
3188 }
3189 }
3190
3191 bool InitializeNode::is_non_zero() {
3192 if (is_complete()) return false;
3193 remove_extra_zeroes();
3194 return (req() > RawStores);
3195 }
3196
3197 void InitializeNode::set_complete(PhaseGVN* phase) {
3198 assert(!is_complete(), "caller responsibility");
3199 _is_complete = Complete;
3200
3201 // After this node is complete, it contains a bunch of
3202 // raw-memory initializations. There is no need for
3203 // it to have anything to do with non-raw memory effects.
3204 // Therefore, tell all non-raw users to re-optimize themselves,
3205 // after skipping the memory effects of this initialization.
3206 PhaseIterGVN* igvn = phase->is_IterGVN();
3207 if (igvn) igvn->add_users_to_worklist(this);
3208 }
3209
3210 // convenience function
3211 // return false if the init contains any stores already
3212 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3213 InitializeNode* init = initialization();
3214 if (init == NULL || init->is_complete()) return false;
3215 init->remove_extra_zeroes();
3216 // for now, if this allocation has already collected any inits, bail:
3217 if (init->is_non_zero()) return false;
3218 init->set_complete(phase);
3219 return true;
3220 }
3221
3222 void InitializeNode::remove_extra_zeroes() {
3223 if (req() == RawStores) return;
3224 Node* zmem = zero_memory();
3225 uint fill = RawStores;
3226 for (uint i = fill; i < req(); i++) {
3227 Node* n = in(i);
3228 if (n->is_top() || n == zmem) continue; // skip
3229 if (fill < i) set_req(fill, n); // compact
3230 ++fill;
3231 }
3232 // delete any empty spaces created:
3233 while (fill < req()) {
3234 del_req(fill);
3235 }
3236 }
3237
3238 // Helper for remembering which stores go with which offsets.
3239 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3240 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3241 intptr_t offset = -1;
3242 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3243 phase, offset);
3244 if (base == NULL) return -1; // something is dead,
3245 if (offset < 0) return -1; // dead, dead
3246 return offset;
3247 }
3248
3249 // Helper for proving that an initialization expression is
3250 // "simple enough" to be folded into an object initialization.
3251 // Attempts to prove that a store's initial value 'n' can be captured
3252 // within the initialization without creating a vicious cycle, such as:
3253 // { Foo p = new Foo(); p.next = p; }
3254 // True for constants and parameters and small combinations thereof.
3255 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3256 if (n == NULL) return true; // (can this really happen?)
3257 if (n->is_Proj()) n = n->in(0);
3258 if (n == this) return false; // found a cycle
3259 if (n->is_Con()) return true;
3260 if (n->is_Start()) return true; // params, etc., are OK
3261 if (n->is_Root()) return true; // even better
3262
3263 Node* ctl = n->in(0);
3264 if (ctl != NULL && !ctl->is_top()) {
3265 if (ctl->is_Proj()) ctl = ctl->in(0);
3266 if (ctl == this) return false;
3267
3268 // If we already know that the enclosing memory op is pinned right after
3269 // the init, then any control flow that the store has picked up
3270 // must have preceded the init, or else be equal to the init.
3271 // Even after loop optimizations (which might change control edges)
3272 // a store is never pinned *before* the availability of its inputs.
3273 if (!MemNode::all_controls_dominate(n, this))
3274 return false; // failed to prove a good control
3275 }
3276
3277 // Check data edges for possible dependencies on 'this'.
3278 if ((count += 1) > 20) return false; // complexity limit
3279 for (uint i = 1; i < n->req(); i++) {
3280 Node* m = n->in(i);
3281 if (m == NULL || m == n || m->is_top()) continue;
3282 uint first_i = n->find_edge(m);
3283 if (i != first_i) continue; // process duplicate edge just once
3284 if (!detect_init_independence(m, count)) {
3285 return false;
3286 }
3287 }
3288
3289 return true;
3290 }
3291
3292 // Here are all the checks a Store must pass before it can be moved into
3293 // an initialization. Returns zero if a check fails.
3294 // On success, returns the (constant) offset to which the store applies,
3295 // within the initialized memory.
3296 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3297 const int FAIL = 0;
3298 if (st->is_unaligned_access()) {
3299 return FAIL;
3300 }
3301 if (st->req() != MemNode::ValueIn + 1)
3302 return FAIL; // an inscrutable StoreNode (card mark?)
3303 Node* ctl = st->in(MemNode::Control);
3304 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3305 return FAIL; // must be unconditional after the initialization
3306 Node* mem = st->in(MemNode::Memory);
3307 if (!(mem->is_Proj() && mem->in(0) == this))
3308 return FAIL; // must not be preceded by other stores
3309 Node* adr = st->in(MemNode::Address);
3310 intptr_t offset;
3311 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3312 if (alloc == NULL)
3313 return FAIL; // inscrutable address
3314 if (alloc != allocation())
3315 return FAIL; // wrong allocation! (store needs to float up)
3316 Node* val = st->in(MemNode::ValueIn);
3317 int complexity_count = 0;
3318 if (!detect_init_independence(val, complexity_count))
3319 return FAIL; // stored value must be 'simple enough'
3320
3321 // The Store can be captured only if nothing after the allocation
3322 // and before the Store is using the memory location that the store
3323 // overwrites.
3324 bool failed = false;
3325 // If is_complete_with_arraycopy() is true the shape of the graph is
3326 // well defined and is safe so no need for extra checks.
3327 if (!is_complete_with_arraycopy()) {
3328 // We are going to look at each use of the memory state following
3329 // the allocation to make sure nothing reads the memory that the
3330 // Store writes.
3331 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3332 int alias_idx = phase->C->get_alias_index(t_adr);
3333 ResourceMark rm;
3334 Unique_Node_List mems;
3335 mems.push(mem);
3336 Node* unique_merge = NULL;
3337 for (uint next = 0; next < mems.size(); ++next) {
3338 Node *m = mems.at(next);
3339 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3340 Node *n = m->fast_out(j);
3341 if (n->outcnt() == 0) {
3342 continue;
3343 }
3344 if (n == st) {
3345 continue;
3346 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3347 // If the control of this use is different from the control
3348 // of the Store which is right after the InitializeNode then
3349 // this node cannot be between the InitializeNode and the
3350 // Store.
3351 continue;
3352 } else if (n->is_MergeMem()) {
3353 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3354 // We can hit a MergeMemNode (that will likely go away
3355 // later) that is a direct use of the memory state
3356 // following the InitializeNode on the same slice as the
3357 // store node that we'd like to capture. We need to check
3358 // the uses of the MergeMemNode.
3359 mems.push(n);
3360 }
3361 } else if (n->is_Mem()) {
3362 Node* other_adr = n->in(MemNode::Address);
3363 if (other_adr == adr) {
3364 failed = true;
3365 break;
3366 } else {
3367 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3368 if (other_t_adr != NULL) {
3369 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3370 if (other_alias_idx == alias_idx) {
3371 // A load from the same memory slice as the store right
3372 // after the InitializeNode. We check the control of the
3373 // object/array that is loaded from. If it's the same as
3374 // the store control then we cannot capture the store.
3375 assert(!n->is_Store(), "2 stores to same slice on same control?");
3376 Node* base = other_adr;
3377 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3378 base = base->in(AddPNode::Base);
3379 if (base != NULL) {
3380 base = base->uncast();
3381 if (base->is_Proj() && base->in(0) == alloc) {
3382 failed = true;
3383 break;
3384 }
3385 }
3386 }
3387 }
3388 }
3389 } else {
3390 failed = true;
3391 break;
3392 }
3393 }
3394 }
3395 }
3396 if (failed) {
3397 if (!can_reshape) {
3398 // We decided we couldn't capture the store during parsing. We
3399 // should try again during the next IGVN once the graph is
3400 // cleaner.
3401 phase->C->record_for_igvn(st);
3402 }
3403 return FAIL;
3404 }
3405
3406 return offset; // success
3407 }
3408
3409 // Find the captured store in(i) which corresponds to the range
3410 // [start..start+size) in the initialized object.
3411 // If there is one, return its index i. If there isn't, return the
3412 // negative of the index where it should be inserted.
3413 // Return 0 if the queried range overlaps an initialization boundary
3414 // or if dead code is encountered.
3415 // If size_in_bytes is zero, do not bother with overlap checks.
3416 int InitializeNode::captured_store_insertion_point(intptr_t start,
3417 int size_in_bytes,
3418 PhaseTransform* phase) {
3419 const int FAIL = 0, MAX_STORE = BytesPerLong;
3420
3421 if (is_complete())
3422 return FAIL; // arraycopy got here first; punt
3423
3424 assert(allocation() != NULL, "must be present");
3425
3426 // no negatives, no header fields:
3427 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3428
3429 // after a certain size, we bail out on tracking all the stores:
3430 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3431 if (start >= ti_limit) return FAIL;
3432
3433 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3434 if (i >= limit) return -(int)i; // not found; here is where to put it
3435
3436 Node* st = in(i);
3437 intptr_t st_off = get_store_offset(st, phase);
3438 if (st_off < 0) {
3439 if (st != zero_memory()) {
3440 return FAIL; // bail out if there is dead garbage
3441 }
3442 } else if (st_off > start) {
3443 // ...we are done, since stores are ordered
3444 if (st_off < start + size_in_bytes) {
3445 return FAIL; // the next store overlaps
3446 }
3447 return -(int)i; // not found; here is where to put it
3448 } else if (st_off < start) {
3449 if (size_in_bytes != 0 &&
3450 start < st_off + MAX_STORE &&
3451 start < st_off + st->as_Store()->memory_size()) {
3452 return FAIL; // the previous store overlaps
3453 }
3454 } else {
3455 if (size_in_bytes != 0 &&
3456 st->as_Store()->memory_size() != size_in_bytes) {
3457 return FAIL; // mismatched store size
3458 }
3459 return i;
3460 }
3461
3462 ++i;
3463 }
3464 }
3465
3466 // Look for a captured store which initializes at the offset 'start'
3467 // with the given size. If there is no such store, and no other
3468 // initialization interferes, then return zero_memory (the memory
3469 // projection of the AllocateNode).
3470 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3471 PhaseTransform* phase) {
3472 assert(stores_are_sane(phase), "");
3473 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3474 if (i == 0) {
3475 return NULL; // something is dead
3476 } else if (i < 0) {
3477 return zero_memory(); // just primordial zero bits here
3478 } else {
3479 Node* st = in(i); // here is the store at this position
3480 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3481 return st;
3482 }
3483 }
3484
3485 // Create, as a raw pointer, an address within my new object at 'offset'.
3486 Node* InitializeNode::make_raw_address(intptr_t offset,
3487 PhaseTransform* phase) {
3488 Node* addr = in(RawAddress);
3489 if (offset != 0) {
3490 Compile* C = phase->C;
3491 addr = phase->transform( new AddPNode(C->top(), addr,
3492 phase->MakeConX(offset)) );
3493 }
3494 return addr;
3495 }
3496
3497 // Clone the given store, converting it into a raw store
3498 // initializing a field or element of my new object.
3499 // Caller is responsible for retiring the original store,
3500 // with subsume_node or the like.
3501 //
3502 // From the example above InitializeNode::InitializeNode,
3503 // here are the old stores to be captured:
3504 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3505 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3506 //
3507 // Here is the changed code; note the extra edges on init:
3508 // alloc = (Allocate ...)
3509 // rawoop = alloc.RawAddress
3510 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3511 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3512 // init = (Initialize alloc.Control alloc.Memory rawoop
3513 // rawstore1 rawstore2)
3514 //
3515 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3516 PhaseTransform* phase, bool can_reshape) {
3517 assert(stores_are_sane(phase), "");
3518
3519 if (start < 0) return NULL;
3520 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3521
3522 Compile* C = phase->C;
3523 int size_in_bytes = st->memory_size();
3524 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3525 if (i == 0) return NULL; // bail out
3526 Node* prev_mem = NULL; // raw memory for the captured store
3527 if (i > 0) {
3528 prev_mem = in(i); // there is a pre-existing store under this one
3529 set_req(i, C->top()); // temporarily disconnect it
3530 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3531 } else {
3532 i = -i; // no pre-existing store
3533 prev_mem = zero_memory(); // a slice of the newly allocated object
3534 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3535 set_req(--i, C->top()); // reuse this edge; it has been folded away
3536 else
3537 ins_req(i, C->top()); // build a new edge
3538 }
3539 Node* new_st = st->clone();
3540 new_st->set_req(MemNode::Control, in(Control));
3541 new_st->set_req(MemNode::Memory, prev_mem);
3542 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3543 new_st = phase->transform(new_st);
3544
3545 // At this point, new_st might have swallowed a pre-existing store
3546 // at the same offset, or perhaps new_st might have disappeared,
3547 // if it redundantly stored the same value (or zero to fresh memory).
3548
3549 // In any case, wire it in:
3550 phase->igvn_rehash_node_delayed(this);
3551 set_req(i, new_st);
3552
3553 // The caller may now kill the old guy.
3554 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3555 assert(check_st == new_st || check_st == NULL, "must be findable");
3556 assert(!is_complete(), "");
3557 return new_st;
3558 }
3559
3560 static bool store_constant(jlong* tiles, int num_tiles,
3561 intptr_t st_off, int st_size,
3562 jlong con) {
3563 if ((st_off & (st_size-1)) != 0)
3564 return false; // strange store offset (assume size==2**N)
3565 address addr = (address)tiles + st_off;
3566 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3567 switch (st_size) {
3568 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3569 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3570 case sizeof(jint): *(jint*) addr = (jint) con; break;
3571 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3572 default: return false; // strange store size (detect size!=2**N here)
3573 }
3574 return true; // return success to caller
3575 }
3576
3577 // Coalesce subword constants into int constants and possibly
3578 // into long constants. The goal, if the CPU permits,
3579 // is to initialize the object with a small number of 64-bit tiles.
3580 // Also, convert floating-point constants to bit patterns.
3581 // Non-constants are not relevant to this pass.
3582 //
3583 // In terms of the running example on InitializeNode::InitializeNode
3584 // and InitializeNode::capture_store, here is the transformation
3585 // of rawstore1 and rawstore2 into rawstore12:
3586 // alloc = (Allocate ...)
3587 // rawoop = alloc.RawAddress
3588 // tile12 = 0x00010002
3589 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3590 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3591 //
3592 void
3593 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3594 Node* size_in_bytes,
3595 PhaseGVN* phase) {
3596 Compile* C = phase->C;
3597
3598 assert(stores_are_sane(phase), "");
3599 // Note: After this pass, they are not completely sane,
3600 // since there may be some overlaps.
3601
3602 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3603
3604 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3605 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3606 size_limit = MIN2(size_limit, ti_limit);
3607 size_limit = align_size_up(size_limit, BytesPerLong);
3608 int num_tiles = size_limit / BytesPerLong;
3609
3610 // allocate space for the tile map:
3611 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3612 jlong tiles_buf[small_len];
3613 Node* nodes_buf[small_len];
3614 jlong inits_buf[small_len];
3615 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3616 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3617 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3618 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3619 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3620 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3621 // tiles: exact bitwise model of all primitive constants
3622 // nodes: last constant-storing node subsumed into the tiles model
3623 // inits: which bytes (in each tile) are touched by any initializations
3624
3625 //// Pass A: Fill in the tile model with any relevant stores.
3626
3627 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3628 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3629 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3630 Node* zmem = zero_memory(); // initially zero memory state
3631 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3632 Node* st = in(i);
3633 intptr_t st_off = get_store_offset(st, phase);
3634
3635 // Figure out the store's offset and constant value:
3636 if (st_off < header_size) continue; //skip (ignore header)
3637 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3638 int st_size = st->as_Store()->memory_size();
3639 if (st_off + st_size > size_limit) break;
3640
3641 // Record which bytes are touched, whether by constant or not.
3642 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3643 continue; // skip (strange store size)
3644
3645 const Type* val = phase->type(st->in(MemNode::ValueIn));
3646 if (!val->singleton()) continue; //skip (non-con store)
3647 BasicType type = val->basic_type();
3648
3649 jlong con = 0;
3650 switch (type) {
3651 case T_INT: con = val->is_int()->get_con(); break;
3652 case T_LONG: con = val->is_long()->get_con(); break;
3653 case T_FLOAT: con = jint_cast(val->getf()); break;
3654 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3655 default: continue; //skip (odd store type)
3656 }
3657
3658 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3659 st->Opcode() == Op_StoreL) {
3660 continue; // This StoreL is already optimal.
3661 }
3662
3663 // Store down the constant.
3664 store_constant(tiles, num_tiles, st_off, st_size, con);
3665
3666 intptr_t j = st_off >> LogBytesPerLong;
3667
3668 if (type == T_INT && st_size == BytesPerInt
3669 && (st_off & BytesPerInt) == BytesPerInt) {
3670 jlong lcon = tiles[j];
3671 if (!Matcher::isSimpleConstant64(lcon) &&
3672 st->Opcode() == Op_StoreI) {
3673 // This StoreI is already optimal by itself.
3674 jint* intcon = (jint*) &tiles[j];
3675 intcon[1] = 0; // undo the store_constant()
3676
3677 // If the previous store is also optimal by itself, back up and
3678 // undo the action of the previous loop iteration... if we can.
3679 // But if we can't, just let the previous half take care of itself.
3680 st = nodes[j];
3681 st_off -= BytesPerInt;
3682 con = intcon[0];
3683 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3684 assert(st_off >= header_size, "still ignoring header");
3685 assert(get_store_offset(st, phase) == st_off, "must be");
3686 assert(in(i-1) == zmem, "must be");
3687 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3688 assert(con == tcon->is_int()->get_con(), "must be");
3689 // Undo the effects of the previous loop trip, which swallowed st:
3690 intcon[0] = 0; // undo store_constant()
3691 set_req(i-1, st); // undo set_req(i, zmem)
3692 nodes[j] = NULL; // undo nodes[j] = st
3693 --old_subword; // undo ++old_subword
3694 }
3695 continue; // This StoreI is already optimal.
3696 }
3697 }
3698
3699 // This store is not needed.
3700 set_req(i, zmem);
3701 nodes[j] = st; // record for the moment
3702 if (st_size < BytesPerLong) // something has changed
3703 ++old_subword; // includes int/float, but who's counting...
3704 else ++old_long;
3705 }
3706
3707 if ((old_subword + old_long) == 0)
3708 return; // nothing more to do
3709
3710 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3711 // Be sure to insert them before overlapping non-constant stores.
3712 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3713 for (int j = 0; j < num_tiles; j++) {
3714 jlong con = tiles[j];
3715 jlong init = inits[j];
3716 if (con == 0) continue;
3717 jint con0, con1; // split the constant, address-wise
3718 jint init0, init1; // split the init map, address-wise
3719 { union { jlong con; jint intcon[2]; } u;
3720 u.con = con;
3721 con0 = u.intcon[0];
3722 con1 = u.intcon[1];
3723 u.con = init;
3724 init0 = u.intcon[0];
3725 init1 = u.intcon[1];
3726 }
3727
3728 Node* old = nodes[j];
3729 assert(old != NULL, "need the prior store");
3730 intptr_t offset = (j * BytesPerLong);
3731
3732 bool split = !Matcher::isSimpleConstant64(con);
3733
3734 if (offset < header_size) {
3735 assert(offset + BytesPerInt >= header_size, "second int counts");
3736 assert(*(jint*)&tiles[j] == 0, "junk in header");
3737 split = true; // only the second word counts
3738 // Example: int a[] = { 42 ... }
3739 } else if (con0 == 0 && init0 == -1) {
3740 split = true; // first word is covered by full inits
3741 // Example: int a[] = { ... foo(), 42 ... }
3742 } else if (con1 == 0 && init1 == -1) {
3743 split = true; // second word is covered by full inits
3744 // Example: int a[] = { ... 42, foo() ... }
3745 }
3746
3747 // Here's a case where init0 is neither 0 nor -1:
3748 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3749 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3750 // In this case the tile is not split; it is (jlong)42.
3751 // The big tile is stored down, and then the foo() value is inserted.
3752 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3753
3754 Node* ctl = old->in(MemNode::Control);
3755 Node* adr = make_raw_address(offset, phase);
3756 const TypePtr* atp = TypeRawPtr::BOTTOM;
3757
3758 // One or two coalesced stores to plop down.
3759 Node* st[2];
3760 intptr_t off[2];
3761 int nst = 0;
3762 if (!split) {
3763 ++new_long;
3764 off[nst] = offset;
3765 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3766 phase->longcon(con), T_LONG, MemNode::unordered);
3767 } else {
3768 // Omit either if it is a zero.
3769 if (con0 != 0) {
3770 ++new_int;
3771 off[nst] = offset;
3772 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3773 phase->intcon(con0), T_INT, MemNode::unordered);
3774 }
3775 if (con1 != 0) {
3776 ++new_int;
3777 offset += BytesPerInt;
3778 adr = make_raw_address(offset, phase);
3779 off[nst] = offset;
3780 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3781 phase->intcon(con1), T_INT, MemNode::unordered);
3782 }
3783 }
3784
3785 // Insert second store first, then the first before the second.
3786 // Insert each one just before any overlapping non-constant stores.
3787 while (nst > 0) {
3788 Node* st1 = st[--nst];
3789 C->copy_node_notes_to(st1, old);
3790 st1 = phase->transform(st1);
3791 offset = off[nst];
3792 assert(offset >= header_size, "do not smash header");
3793 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3794 guarantee(ins_idx != 0, "must re-insert constant store");
3795 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3796 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3797 set_req(--ins_idx, st1);
3798 else
3799 ins_req(ins_idx, st1);
3800 }
3801 }
3802
3803 if (PrintCompilation && WizardMode)
3804 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3805 old_subword, old_long, new_int, new_long);
3806 if (C->log() != NULL)
3807 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3808 old_subword, old_long, new_int, new_long);
3809
3810 // Clean up any remaining occurrences of zmem:
3811 remove_extra_zeroes();
3812 }
3813
3814 // Explore forward from in(start) to find the first fully initialized
3815 // word, and return its offset. Skip groups of subword stores which
3816 // together initialize full words. If in(start) is itself part of a
3817 // fully initialized word, return the offset of in(start). If there
3818 // are no following full-word stores, or if something is fishy, return
3819 // a negative value.
3820 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3821 int int_map = 0;
3822 intptr_t int_map_off = 0;
3823 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3824
3825 for (uint i = start, limit = req(); i < limit; i++) {
3826 Node* st = in(i);
3827
3828 intptr_t st_off = get_store_offset(st, phase);
3829 if (st_off < 0) break; // return conservative answer
3830
3831 int st_size = st->as_Store()->memory_size();
3832 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3833 return st_off; // we found a complete word init
3834 }
3835
3836 // update the map:
3837
3838 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3839 if (this_int_off != int_map_off) {
3840 // reset the map:
3841 int_map = 0;
3842 int_map_off = this_int_off;
3843 }
3844
3845 int subword_off = st_off - this_int_off;
3846 int_map |= right_n_bits(st_size) << subword_off;
3847 if ((int_map & FULL_MAP) == FULL_MAP) {
3848 return this_int_off; // we found a complete word init
3849 }
3850
3851 // Did this store hit or cross the word boundary?
3852 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3853 if (next_int_off == this_int_off + BytesPerInt) {
3854 // We passed the current int, without fully initializing it.
3855 int_map_off = next_int_off;
3856 int_map >>= BytesPerInt;
3857 } else if (next_int_off > this_int_off + BytesPerInt) {
3858 // We passed the current and next int.
3859 return this_int_off + BytesPerInt;
3860 }
3861 }
3862
3863 return -1;
3864 }
3865
3866
3867 // Called when the associated AllocateNode is expanded into CFG.
3868 // At this point, we may perform additional optimizations.
3869 // Linearize the stores by ascending offset, to make memory
3870 // activity as coherent as possible.
3871 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3872 intptr_t header_size,
3873 Node* size_in_bytes,
3874 PhaseGVN* phase) {
3875 assert(!is_complete(), "not already complete");
3876 assert(stores_are_sane(phase), "");
3877 assert(allocation() != NULL, "must be present");
3878
3879 remove_extra_zeroes();
3880
3881 if (ReduceFieldZeroing || ReduceBulkZeroing)
3882 // reduce instruction count for common initialization patterns
3883 coalesce_subword_stores(header_size, size_in_bytes, phase);
3884
3885 Node* zmem = zero_memory(); // initially zero memory state
3886 Node* inits = zmem; // accumulating a linearized chain of inits
3887 #ifdef ASSERT
3888 intptr_t first_offset = allocation()->minimum_header_size();
3889 intptr_t last_init_off = first_offset; // previous init offset
3890 intptr_t last_init_end = first_offset; // previous init offset+size
3891 intptr_t last_tile_end = first_offset; // previous tile offset+size
3892 #endif
3893 intptr_t zeroes_done = header_size;
3894
3895 bool do_zeroing = true; // we might give up if inits are very sparse
3896 int big_init_gaps = 0; // how many large gaps have we seen?
3897
3898 if (UseTLAB && ZeroTLAB) do_zeroing = false;
3899 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3900
3901 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3902 Node* st = in(i);
3903 intptr_t st_off = get_store_offset(st, phase);
3904 if (st_off < 0)
3905 break; // unknown junk in the inits
3906 if (st->in(MemNode::Memory) != zmem)
3907 break; // complicated store chains somehow in list
3908
3909 int st_size = st->as_Store()->memory_size();
3910 intptr_t next_init_off = st_off + st_size;
3911
3912 if (do_zeroing && zeroes_done < next_init_off) {
3913 // See if this store needs a zero before it or under it.
3914 intptr_t zeroes_needed = st_off;
3915
3916 if (st_size < BytesPerInt) {
3917 // Look for subword stores which only partially initialize words.
3918 // If we find some, we must lay down some word-level zeroes first,
3919 // underneath the subword stores.
3920 //
3921 // Examples:
3922 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3923 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3924 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3925 //
3926 // Note: coalesce_subword_stores may have already done this,
3927 // if it was prompted by constant non-zero subword initializers.
3928 // But this case can still arise with non-constant stores.
3929
3930 intptr_t next_full_store = find_next_fullword_store(i, phase);
3931
3932 // In the examples above:
3933 // in(i) p q r s x y z
3934 // st_off 12 13 14 15 12 13 14
3935 // st_size 1 1 1 1 1 1 1
3936 // next_full_s. 12 16 16 16 16 16 16
3937 // z's_done 12 16 16 16 12 16 12
3938 // z's_needed 12 16 16 16 16 16 16
3939 // zsize 0 0 0 0 4 0 4
3940 if (next_full_store < 0) {
3941 // Conservative tack: Zero to end of current word.
3942 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3943 } else {
3944 // Zero to beginning of next fully initialized word.
3945 // Or, don't zero at all, if we are already in that word.
3946 assert(next_full_store >= zeroes_needed, "must go forward");
3947 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3948 zeroes_needed = next_full_store;
3949 }
3950 }
3951
3952 if (zeroes_needed > zeroes_done) {
3953 intptr_t zsize = zeroes_needed - zeroes_done;
3954 // Do some incremental zeroing on rawmem, in parallel with inits.
3955 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3956 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3957 zeroes_done, zeroes_needed,
3958 phase);
3959 zeroes_done = zeroes_needed;
3960 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
3961 do_zeroing = false; // leave the hole, next time
3962 }
3963 }
3964
3965 // Collect the store and move on:
3966 st->set_req(MemNode::Memory, inits);
3967 inits = st; // put it on the linearized chain
3968 set_req(i, zmem); // unhook from previous position
3969
3970 if (zeroes_done == st_off)
3971 zeroes_done = next_init_off;
3972
3973 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3974
3975 #ifdef ASSERT
3976 // Various order invariants. Weaker than stores_are_sane because
3977 // a large constant tile can be filled in by smaller non-constant stores.
3978 assert(st_off >= last_init_off, "inits do not reverse");
3979 last_init_off = st_off;
3980 const Type* val = NULL;
3981 if (st_size >= BytesPerInt &&
3982 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3983 (int)val->basic_type() < (int)T_OBJECT) {
3984 assert(st_off >= last_tile_end, "tiles do not overlap");
3985 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3986 last_tile_end = MAX2(last_tile_end, next_init_off);
3987 } else {
3988 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3989 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3990 assert(st_off >= last_init_end, "inits do not overlap");
3991 last_init_end = next_init_off; // it's a non-tile
3992 }
3993 #endif //ASSERT
3994 }
3995
3996 remove_extra_zeroes(); // clear out all the zmems left over
3997 add_req(inits);
3998
3999 if (!(UseTLAB && ZeroTLAB)) {
4000 // If anything remains to be zeroed, zero it all now.
4001 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
4002 // if it is the last unused 4 bytes of an instance, forget about it
4003 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4004 if (zeroes_done + BytesPerLong >= size_limit) {
4005 assert(allocation() != NULL, "");
4006 if (allocation()->Opcode() == Op_Allocate) {
4007 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
4008 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4009 if (zeroes_done == k->layout_helper())
4010 zeroes_done = size_limit;
4011 }
4012 }
4013 if (zeroes_done < size_limit) {
4014 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4015 zeroes_done, size_in_bytes, phase);
4016 }
4017 }
4018
4019 set_complete(phase);
4020 return rawmem;
4021 }
4022
4023
4024 #ifdef ASSERT
4025 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4026 if (is_complete())
4027 return true; // stores could be anything at this point
4028 assert(allocation() != NULL, "must be present");
4029 intptr_t last_off = allocation()->minimum_header_size();
4030 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4031 Node* st = in(i);
4032 intptr_t st_off = get_store_offset(st, phase);
4033 if (st_off < 0) continue; // ignore dead garbage
4034 if (last_off > st_off) {
4035 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4036 this->dump(2);
4037 assert(false, "ascending store offsets");
4038 return false;
4039 }
4040 last_off = st_off + st->as_Store()->memory_size();
4041 }
4042 return true;
4043 }
4044 #endif //ASSERT
4045
4046
4047
4048
4049 //============================MergeMemNode=====================================
4050 //
4051 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4052 // contributing store or call operations. Each contributor provides the memory
4053 // state for a particular "alias type" (see Compile::alias_type). For example,
4054 // if a MergeMem has an input X for alias category #6, then any memory reference
4055 // to alias category #6 may use X as its memory state input, as an exact equivalent
4056 // to using the MergeMem as a whole.
4057 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4058 //
4059 // (Here, the <N> notation gives the index of the relevant adr_type.)
4060 //
4061 // In one special case (and more cases in the future), alias categories overlap.
4062 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4063 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4064 // it is exactly equivalent to that state W:
4065 // MergeMem(<Bot>: W) <==> W
4066 //
4067 // Usually, the merge has more than one input. In that case, where inputs
4068 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4069 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4070 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4071 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4072 //
4073 // A merge can take a "wide" memory state as one of its narrow inputs.
4074 // This simply means that the merge observes out only the relevant parts of
4075 // the wide input. That is, wide memory states arriving at narrow merge inputs
4076 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4077 //
4078 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4079 // and that memory slices "leak through":
4080 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4081 //
4082 // But, in such a cascade, repeated memory slices can "block the leak":
4083 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4084 //
4085 // In the last example, Y is not part of the combined memory state of the
4086 // outermost MergeMem. The system must, of course, prevent unschedulable
4087 // memory states from arising, so you can be sure that the state Y is somehow
4088 // a precursor to state Y'.
4089 //
4090 //
4091 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4092 // of each MergeMemNode array are exactly the numerical alias indexes, including
4093 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4094 // Compile::alias_type (and kin) produce and manage these indexes.
4095 //
4096 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4097 // (Note that this provides quick access to the top node inside MergeMem methods,
4098 // without the need to reach out via TLS to Compile::current.)
4099 //
4100 // As a consequence of what was just described, a MergeMem that represents a full
4101 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4102 // containing all alias categories.
4103 //
4104 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4105 //
4106 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4107 // a memory state for the alias type <N>, or else the top node, meaning that
4108 // there is no particular input for that alias type. Note that the length of
4109 // a MergeMem is variable, and may be extended at any time to accommodate new
4110 // memory states at larger alias indexes. When merges grow, they are of course
4111 // filled with "top" in the unused in() positions.
4112 //
4113 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4114 // (Top was chosen because it works smoothly with passes like GCM.)
4115 //
4116 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4117 // the type of random VM bits like TLS references.) Since it is always the
4118 // first non-Bot memory slice, some low-level loops use it to initialize an
4119 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4120 //
4121 //
4122 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4123 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4124 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4125 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4126 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4127 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4128 //
4129 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4130 // really that different from the other memory inputs. An abbreviation called
4131 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4132 //
4133 //
4134 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4135 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4136 // that "emerges though" the base memory will be marked as excluding the alias types
4137 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4138 //
4139 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4140 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4141 //
4142 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4143 // (It is currently unimplemented.) As you can see, the resulting merge is
4144 // actually a disjoint union of memory states, rather than an overlay.
4145 //
4146
4147 //------------------------------MergeMemNode-----------------------------------
4148 Node* MergeMemNode::make_empty_memory() {
4149 Node* empty_memory = (Node*) Compile::current()->top();
4150 assert(empty_memory->is_top(), "correct sentinel identity");
4151 return empty_memory;
4152 }
4153
4154 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4155 init_class_id(Class_MergeMem);
4156 // all inputs are nullified in Node::Node(int)
4157 // set_input(0, NULL); // no control input
4158
4159 // Initialize the edges uniformly to top, for starters.
4160 Node* empty_mem = make_empty_memory();
4161 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4162 init_req(i,empty_mem);
4163 }
4164 assert(empty_memory() == empty_mem, "");
4165
4166 if( new_base != NULL && new_base->is_MergeMem() ) {
4167 MergeMemNode* mdef = new_base->as_MergeMem();
4168 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4169 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4170 mms.set_memory(mms.memory2());
4171 }
4172 assert(base_memory() == mdef->base_memory(), "");
4173 } else {
4174 set_base_memory(new_base);
4175 }
4176 }
4177
4178 // Make a new, untransformed MergeMem with the same base as 'mem'.
4179 // If mem is itself a MergeMem, populate the result with the same edges.
4180 MergeMemNode* MergeMemNode::make(Node* mem) {
4181 return new MergeMemNode(mem);
4182 }
4183
4184 //------------------------------cmp--------------------------------------------
4185 uint MergeMemNode::hash() const { return NO_HASH; }
4186 uint MergeMemNode::cmp( const Node &n ) const {
4187 return (&n == this); // Always fail except on self
4188 }
4189
4190 //------------------------------Identity---------------------------------------
4191 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4192 // Identity if this merge point does not record any interesting memory
4193 // disambiguations.
4194 Node* base_mem = base_memory();
4195 Node* empty_mem = empty_memory();
4196 if (base_mem != empty_mem) { // Memory path is not dead?
4197 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4198 Node* mem = in(i);
4199 if (mem != empty_mem && mem != base_mem) {
4200 return this; // Many memory splits; no change
4201 }
4202 }
4203 }
4204 return base_mem; // No memory splits; ID on the one true input
4205 }
4206
4207 //------------------------------Ideal------------------------------------------
4208 // This method is invoked recursively on chains of MergeMem nodes
4209 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4210 // Remove chain'd MergeMems
4211 //
4212 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4213 // relative to the "in(Bot)". Since we are patching both at the same time,
4214 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4215 // but rewrite each "in(i)" relative to the new "in(Bot)".
4216 Node *progress = NULL;
4217
4218
4219 Node* old_base = base_memory();
4220 Node* empty_mem = empty_memory();
4221 if (old_base == empty_mem)
4222 return NULL; // Dead memory path.
4223
4224 MergeMemNode* old_mbase;
4225 if (old_base != NULL && old_base->is_MergeMem())
4226 old_mbase = old_base->as_MergeMem();
4227 else
4228 old_mbase = NULL;
4229 Node* new_base = old_base;
4230
4231 // simplify stacked MergeMems in base memory
4232 if (old_mbase) new_base = old_mbase->base_memory();
4233
4234 // the base memory might contribute new slices beyond my req()
4235 if (old_mbase) grow_to_match(old_mbase);
4236
4237 // Look carefully at the base node if it is a phi.
4238 PhiNode* phi_base;
4239 if (new_base != NULL && new_base->is_Phi())
4240 phi_base = new_base->as_Phi();
4241 else
4242 phi_base = NULL;
4243
4244 Node* phi_reg = NULL;
4245 uint phi_len = (uint)-1;
4246 if (phi_base != NULL && !phi_base->is_copy()) {
4247 // do not examine phi if degraded to a copy
4248 phi_reg = phi_base->region();
4249 phi_len = phi_base->req();
4250 // see if the phi is unfinished
4251 for (uint i = 1; i < phi_len; i++) {
4252 if (phi_base->in(i) == NULL) {
4253 // incomplete phi; do not look at it yet!
4254 phi_reg = NULL;
4255 phi_len = (uint)-1;
4256 break;
4257 }
4258 }
4259 }
4260
4261 // Note: We do not call verify_sparse on entry, because inputs
4262 // can normalize to the base_memory via subsume_node or similar
4263 // mechanisms. This method repairs that damage.
4264
4265 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4266
4267 // Look at each slice.
4268 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4269 Node* old_in = in(i);
4270 // calculate the old memory value
4271 Node* old_mem = old_in;
4272 if (old_mem == empty_mem) old_mem = old_base;
4273 assert(old_mem == memory_at(i), "");
4274
4275 // maybe update (reslice) the old memory value
4276
4277 // simplify stacked MergeMems
4278 Node* new_mem = old_mem;
4279 MergeMemNode* old_mmem;
4280 if (old_mem != NULL && old_mem->is_MergeMem())
4281 old_mmem = old_mem->as_MergeMem();
4282 else
4283 old_mmem = NULL;
4284 if (old_mmem == this) {
4285 // This can happen if loops break up and safepoints disappear.
4286 // A merge of BotPtr (default) with a RawPtr memory derived from a
4287 // safepoint can be rewritten to a merge of the same BotPtr with
4288 // the BotPtr phi coming into the loop. If that phi disappears
4289 // also, we can end up with a self-loop of the mergemem.
4290 // In general, if loops degenerate and memory effects disappear,
4291 // a mergemem can be left looking at itself. This simply means
4292 // that the mergemem's default should be used, since there is
4293 // no longer any apparent effect on this slice.
4294 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4295 // from start. Update the input to TOP.
4296 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4297 }
4298 else if (old_mmem != NULL) {
4299 new_mem = old_mmem->memory_at(i);
4300 }
4301 // else preceding memory was not a MergeMem
4302
4303 // replace equivalent phis (unfortunately, they do not GVN together)
4304 if (new_mem != NULL && new_mem != new_base &&
4305 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4306 if (new_mem->is_Phi()) {
4307 PhiNode* phi_mem = new_mem->as_Phi();
4308 for (uint i = 1; i < phi_len; i++) {
4309 if (phi_base->in(i) != phi_mem->in(i)) {
4310 phi_mem = NULL;
4311 break;
4312 }
4313 }
4314 if (phi_mem != NULL) {
4315 // equivalent phi nodes; revert to the def
4316 new_mem = new_base;
4317 }
4318 }
4319 }
4320
4321 // maybe store down a new value
4322 Node* new_in = new_mem;
4323 if (new_in == new_base) new_in = empty_mem;
4324
4325 if (new_in != old_in) {
4326 // Warning: Do not combine this "if" with the previous "if"
4327 // A memory slice might have be be rewritten even if it is semantically
4328 // unchanged, if the base_memory value has changed.
4329 set_req(i, new_in);
4330 progress = this; // Report progress
4331 }
4332 }
4333
4334 if (new_base != old_base) {
4335 set_req(Compile::AliasIdxBot, new_base);
4336 // Don't use set_base_memory(new_base), because we need to update du.
4337 assert(base_memory() == new_base, "");
4338 progress = this;
4339 }
4340
4341 if( base_memory() == this ) {
4342 // a self cycle indicates this memory path is dead
4343 set_req(Compile::AliasIdxBot, empty_mem);
4344 }
4345
4346 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4347 // Recursion must occur after the self cycle check above
4348 if( base_memory()->is_MergeMem() ) {
4349 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4350 Node *m = phase->transform(new_mbase); // Rollup any cycles
4351 if( m != NULL && (m->is_top() ||
4352 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4353 // propagate rollup of dead cycle to self
4354 set_req(Compile::AliasIdxBot, empty_mem);
4355 }
4356 }
4357
4358 if( base_memory() == empty_mem ) {
4359 progress = this;
4360 // Cut inputs during Parse phase only.
4361 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4362 if( !can_reshape ) {
4363 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4364 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4365 }
4366 }
4367 }
4368
4369 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4370 // Check if PhiNode::Ideal's "Split phis through memory merges"
4371 // transform should be attempted. Look for this->phi->this cycle.
4372 uint merge_width = req();
4373 if (merge_width > Compile::AliasIdxRaw) {
4374 PhiNode* phi = base_memory()->as_Phi();
4375 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4376 if (phi->in(i) == this) {
4377 phase->is_IterGVN()->_worklist.push(phi);
4378 break;
4379 }
4380 }
4381 }
4382 }
4383
4384 assert(progress || verify_sparse(), "please, no dups of base");
4385 return progress;
4386 }
4387
4388 //-------------------------set_base_memory-------------------------------------
4389 void MergeMemNode::set_base_memory(Node *new_base) {
4390 Node* empty_mem = empty_memory();
4391 set_req(Compile::AliasIdxBot, new_base);
4392 assert(memory_at(req()) == new_base, "must set default memory");
4393 // Clear out other occurrences of new_base:
4394 if (new_base != empty_mem) {
4395 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4396 if (in(i) == new_base) set_req(i, empty_mem);
4397 }
4398 }
4399 }
4400
4401 //------------------------------out_RegMask------------------------------------
4402 const RegMask &MergeMemNode::out_RegMask() const {
4403 return RegMask::Empty;
4404 }
4405
4406 //------------------------------dump_spec--------------------------------------
4407 #ifndef PRODUCT
4408 void MergeMemNode::dump_spec(outputStream *st) const {
4409 st->print(" {");
4410 Node* base_mem = base_memory();
4411 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4412 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4413 if (mem == base_mem) { st->print(" -"); continue; }
4414 st->print( " N%d:", mem->_idx );
4415 Compile::current()->get_adr_type(i)->dump_on(st);
4416 }
4417 st->print(" }");
4418 }
4419 #endif // !PRODUCT
4420
4421
4422 #ifdef ASSERT
4423 static bool might_be_same(Node* a, Node* b) {
4424 if (a == b) return true;
4425 if (!(a->is_Phi() || b->is_Phi())) return false;
4426 // phis shift around during optimization
4427 return true; // pretty stupid...
4428 }
4429
4430 // verify a narrow slice (either incoming or outgoing)
4431 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4432 if (!VerifyAliases) return; // don't bother to verify unless requested
4433 if (is_error_reported()) return; // muzzle asserts when debugging an error
4434 if (Node::in_dump()) return; // muzzle asserts when printing
4435 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4436 assert(n != NULL, "");
4437 // Elide intervening MergeMem's
4438 while (n->is_MergeMem()) {
4439 n = n->as_MergeMem()->memory_at(alias_idx);
4440 }
4441 Compile* C = Compile::current();
4442 const TypePtr* n_adr_type = n->adr_type();
4443 if (n == m->empty_memory()) {
4444 // Implicit copy of base_memory()
4445 } else if (n_adr_type != TypePtr::BOTTOM) {
4446 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4447 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4448 } else {
4449 // A few places like make_runtime_call "know" that VM calls are narrow,
4450 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4451 bool expected_wide_mem = false;
4452 if (n == m->base_memory()) {
4453 expected_wide_mem = true;
4454 } else if (alias_idx == Compile::AliasIdxRaw ||
4455 n == m->memory_at(Compile::AliasIdxRaw)) {
4456 expected_wide_mem = true;
4457 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4458 // memory can "leak through" calls on channels that
4459 // are write-once. Allow this also.
4460 expected_wide_mem = true;
4461 }
4462 assert(expected_wide_mem, "expected narrow slice replacement");
4463 }
4464 }
4465 #else // !ASSERT
4466 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4467 #endif
4468
4469
4470 //-----------------------------memory_at---------------------------------------
4471 Node* MergeMemNode::memory_at(uint alias_idx) const {
4472 assert(alias_idx >= Compile::AliasIdxRaw ||
4473 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4474 "must avoid base_memory and AliasIdxTop");
4475
4476 // Otherwise, it is a narrow slice.
4477 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4478 Compile *C = Compile::current();
4479 if (is_empty_memory(n)) {
4480 // the array is sparse; empty slots are the "top" node
4481 n = base_memory();
4482 assert(Node::in_dump()
4483 || n == NULL || n->bottom_type() == Type::TOP
4484 || n->adr_type() == NULL // address is TOP
4485 || n->adr_type() == TypePtr::BOTTOM
4486 || n->adr_type() == TypeRawPtr::BOTTOM
4487 || Compile::current()->AliasLevel() == 0,
4488 "must be a wide memory");
4489 // AliasLevel == 0 if we are organizing the memory states manually.
4490 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4491 } else {
4492 // make sure the stored slice is sane
4493 #ifdef ASSERT
4494 if (is_error_reported() || Node::in_dump()) {
4495 } else if (might_be_same(n, base_memory())) {
4496 // Give it a pass: It is a mostly harmless repetition of the base.
4497 // This can arise normally from node subsumption during optimization.
4498 } else {
4499 verify_memory_slice(this, alias_idx, n);
4500 }
4501 #endif
4502 }
4503 return n;
4504 }
4505
4506 //---------------------------set_memory_at-------------------------------------
4507 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4508 verify_memory_slice(this, alias_idx, n);
4509 Node* empty_mem = empty_memory();
4510 if (n == base_memory()) n = empty_mem; // collapse default
4511 uint need_req = alias_idx+1;
4512 if (req() < need_req) {
4513 if (n == empty_mem) return; // already the default, so do not grow me
4514 // grow the sparse array
4515 do {
4516 add_req(empty_mem);
4517 } while (req() < need_req);
4518 }
4519 set_req( alias_idx, n );
4520 }
4521
4522
4523
4524 //--------------------------iteration_setup------------------------------------
4525 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4526 if (other != NULL) {
4527 grow_to_match(other);
4528 // invariant: the finite support of mm2 is within mm->req()
4529 #ifdef ASSERT
4530 for (uint i = req(); i < other->req(); i++) {
4531 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4532 }
4533 #endif
4534 }
4535 // Replace spurious copies of base_memory by top.
4536 Node* base_mem = base_memory();
4537 if (base_mem != NULL && !base_mem->is_top()) {
4538 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4539 if (in(i) == base_mem)
4540 set_req(i, empty_memory());
4541 }
4542 }
4543 }
4544
4545 //---------------------------grow_to_match-------------------------------------
4546 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4547 Node* empty_mem = empty_memory();
4548 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4549 // look for the finite support of the other memory
4550 for (uint i = other->req(); --i >= req(); ) {
4551 if (other->in(i) != empty_mem) {
4552 uint new_len = i+1;
4553 while (req() < new_len) add_req(empty_mem);
4554 break;
4555 }
4556 }
4557 }
4558
4559 //---------------------------verify_sparse-------------------------------------
4560 #ifndef PRODUCT
4561 bool MergeMemNode::verify_sparse() const {
4562 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4563 Node* base_mem = base_memory();
4564 // The following can happen in degenerate cases, since empty==top.
4565 if (is_empty_memory(base_mem)) return true;
4566 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4567 assert(in(i) != NULL, "sane slice");
4568 if (in(i) == base_mem) return false; // should have been the sentinel value!
4569 }
4570 return true;
4571 }
4572
4573 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4574 Node* n;
4575 n = mm->in(idx);
4576 if (mem == n) return true; // might be empty_memory()
4577 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4578 if (mem == n) return true;
4579 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4580 if (mem == n) return true;
4581 if (n == NULL) break;
4582 }
4583 return false;
4584 }
4585 #endif // !PRODUCT