1 /*
2 * Copyright (c) 1997, 2021, 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/javaClasses.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "gc/shared/tlab_globals.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "oops/objArrayKlass.hpp"
34 #include "opto/addnode.hpp"
35 #include "opto/arraycopynode.hpp"
36 #include "opto/cfgnode.hpp"
37 #include "opto/regalloc.hpp"
38 #include "opto/compile.hpp"
39 #include "opto/connode.hpp"
40 #include "opto/convertnode.hpp"
41 #include "opto/loopnode.hpp"
42 #include "opto/machnode.hpp"
43 #include "opto/matcher.hpp"
44 #include "opto/memnode.hpp"
45 #include "opto/mulnode.hpp"
46 #include "opto/narrowptrnode.hpp"
47 #include "opto/phaseX.hpp"
48 #include "opto/regmask.hpp"
49 #include "opto/rootnode.hpp"
50 #include "opto/vectornode.hpp"
51 #include "utilities/align.hpp"
52 #include "utilities/copy.hpp"
53 #include "utilities/macros.hpp"
54 #include "utilities/powerOfTwo.hpp"
55 #include "utilities/vmError.hpp"
56
57 // Portions of code courtesy of Clifford Click
58
59 // Optimization - Graph Style
60
61 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
62
63 //=============================================================================
64 uint MemNode::size_of() const { return sizeof(*this); }
65
66 const TypePtr *MemNode::adr_type() const {
67 Node* adr = in(Address);
68 if (adr == NULL) return NULL; // node is dead
69 const TypePtr* cross_check = NULL;
70 DEBUG_ONLY(cross_check = _adr_type);
71 return calculate_adr_type(adr->bottom_type(), cross_check);
72 }
73
74 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
75 if (adr != NULL) {
76 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
77 return true;
78 }
79 }
80 return false;
81 }
82
83 #ifndef PRODUCT
84 void MemNode::dump_spec(outputStream *st) const {
85 if (in(Address) == NULL) return; // node is dead
86 #ifndef ASSERT
87 // fake the missing field
88 const TypePtr* _adr_type = NULL;
89 if (in(Address) != NULL)
90 _adr_type = in(Address)->bottom_type()->isa_ptr();
91 #endif
92 dump_adr_type(this, _adr_type, st);
93
94 Compile* C = Compile::current();
95 if (C->alias_type(_adr_type)->is_volatile()) {
96 st->print(" Volatile!");
97 }
98 if (_unaligned_access) {
99 st->print(" unaligned");
100 }
101 if (_mismatched_access) {
102 st->print(" mismatched");
103 }
104 if (_unsafe_access) {
105 st->print(" unsafe");
106 }
107 }
108
109 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
110 st->print(" @");
111 if (adr_type == NULL) {
112 st->print("NULL");
113 } else {
114 adr_type->dump_on(st);
115 Compile* C = Compile::current();
116 Compile::AliasType* atp = NULL;
117 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
118 if (atp == NULL)
119 st->print(", idx=?\?;");
120 else if (atp->index() == Compile::AliasIdxBot)
121 st->print(", idx=Bot;");
122 else if (atp->index() == Compile::AliasIdxTop)
123 st->print(", idx=Top;");
124 else if (atp->index() == Compile::AliasIdxRaw)
125 st->print(", idx=Raw;");
126 else {
127 ciField* field = atp->field();
128 if (field) {
129 st->print(", name=");
130 field->print_name_on(st);
131 }
132 st->print(", idx=%d;", atp->index());
133 }
134 }
135 }
136
137 extern void print_alias_types();
138
139 #endif
140
141 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
142 assert((t_oop != NULL), "sanity");
143 bool is_instance = t_oop->is_known_instance_field();
144 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
145 (load != NULL) && load->is_Load() &&
146 (phase->is_IterGVN() != NULL);
147 if (!(is_instance || is_boxed_value_load))
148 return mchain; // don't try to optimize non-instance types
149 uint instance_id = t_oop->instance_id();
150 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
151 Node *prev = NULL;
152 Node *result = mchain;
153 while (prev != result) {
154 prev = result;
155 if (result == start_mem)
156 break; // hit one of our sentinels
157 // skip over a call which does not affect this memory slice
158 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
159 Node *proj_in = result->in(0);
160 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
161 break; // hit one of our sentinels
162 } else if (proj_in->is_Call()) {
163 // ArrayCopyNodes processed here as well
164 CallNode *call = proj_in->as_Call();
165 if (!call->may_modify(t_oop, phase)) { // returns false for instances
166 result = call->in(TypeFunc::Memory);
167 }
168 } else if (proj_in->is_Initialize()) {
169 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
170 // Stop if this is the initialization for the object instance which
171 // contains this memory slice, otherwise skip over it.
172 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
173 break;
174 }
175 if (is_instance) {
176 result = proj_in->in(TypeFunc::Memory);
177 } else if (is_boxed_value_load) {
178 Node* klass = alloc->in(AllocateNode::KlassNode);
179 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
180 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
181 result = proj_in->in(TypeFunc::Memory); // not related allocation
182 }
183 }
184 } else if (proj_in->is_MemBar()) {
185 ArrayCopyNode* ac = NULL;
186 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
187 break;
188 }
189 result = proj_in->in(TypeFunc::Memory);
190 } else {
191 assert(false, "unexpected projection");
192 }
193 } else if (result->is_ClearArray()) {
194 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
195 // Can not bypass initialization of the instance
196 // we are looking for.
197 break;
198 }
199 // Otherwise skip it (the call updated 'result' value).
200 } else if (result->is_MergeMem()) {
201 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
202 }
203 }
204 return result;
205 }
206
207 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
208 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
209 if (t_oop == NULL)
210 return mchain; // don't try to optimize non-oop types
211 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
212 bool is_instance = t_oop->is_known_instance_field();
213 PhaseIterGVN *igvn = phase->is_IterGVN();
214 if (is_instance && igvn != NULL && result->is_Phi()) {
215 PhiNode *mphi = result->as_Phi();
216 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
217 const TypePtr *t = mphi->adr_type();
218 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
219 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
220 t->is_oopptr()->cast_to_exactness(true)
221 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
222 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
223 // clone the Phi with our address type
224 result = mphi->split_out_instance(t_adr, igvn);
225 } else {
226 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
227 }
228 }
229 return result;
230 }
231
232 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
233 uint alias_idx = phase->C->get_alias_index(tp);
234 Node *mem = mmem;
235 #ifdef ASSERT
236 {
237 // Check that current type is consistent with the alias index used during graph construction
238 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
239 bool consistent = adr_check == NULL || adr_check->empty() ||
240 phase->C->must_alias(adr_check, alias_idx );
241 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
242 if( !consistent && adr_check != NULL && !adr_check->empty() &&
243 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
244 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
245 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
246 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
247 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
248 // don't assert if it is dead code.
249 consistent = true;
250 }
251 if( !consistent ) {
252 st->print("alias_idx==%d, adr_check==", alias_idx);
253 if( adr_check == NULL ) {
254 st->print("NULL");
255 } else {
256 adr_check->dump();
257 }
258 st->cr();
259 print_alias_types();
260 assert(consistent, "adr_check must match alias idx");
261 }
262 }
263 #endif
264 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
265 // means an array I have not precisely typed yet. Do not do any
266 // alias stuff with it any time soon.
267 const TypeOopPtr *toop = tp->isa_oopptr();
268 if( tp->base() != Type::AnyPtr &&
269 !(toop &&
270 toop->klass() != NULL &&
271 toop->klass()->is_java_lang_Object() &&
272 toop->offset() == Type::OffsetBot) ) {
273 // compress paths and change unreachable cycles to TOP
274 // If not, we can update the input infinitely along a MergeMem cycle
275 // Equivalent code in PhiNode::Ideal
276 Node* m = phase->transform(mmem);
277 // If transformed to a MergeMem, get the desired slice
278 // Otherwise the returned node represents memory for every slice
279 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
280 // Update input if it is progress over what we have now
281 }
282 return mem;
283 }
284
285 //--------------------------Ideal_common---------------------------------------
286 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
287 // Unhook non-raw memories from complete (macro-expanded) initializations.
288 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
289 // If our control input is a dead region, kill all below the region
290 Node *ctl = in(MemNode::Control);
291 if (ctl && remove_dead_region(phase, can_reshape))
292 return this;
293 ctl = in(MemNode::Control);
294 // Don't bother trying to transform a dead node
295 if (ctl && ctl->is_top()) return NodeSentinel;
296
297 PhaseIterGVN *igvn = phase->is_IterGVN();
298 // Wait if control on the worklist.
299 if (ctl && can_reshape && igvn != NULL) {
300 Node* bol = NULL;
301 Node* cmp = NULL;
302 if (ctl->in(0)->is_If()) {
303 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
304 bol = ctl->in(0)->in(1);
305 if (bol->is_Bool())
306 cmp = ctl->in(0)->in(1)->in(1);
307 }
308 if (igvn->_worklist.member(ctl) ||
309 (bol != NULL && igvn->_worklist.member(bol)) ||
310 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
311 // This control path may be dead.
312 // Delay this memory node transformation until the control is processed.
313 igvn->_worklist.push(this);
314 return NodeSentinel; // caller will return NULL
315 }
316 }
317 // Ignore if memory is dead, or self-loop
318 Node *mem = in(MemNode::Memory);
319 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
320 assert(mem != this, "dead loop in MemNode::Ideal");
321
322 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
323 // This memory slice may be dead.
324 // Delay this mem node transformation until the memory is processed.
325 igvn->_worklist.push(this);
326 return NodeSentinel; // caller will return NULL
327 }
328
329 Node *address = in(MemNode::Address);
330 const Type *t_adr = phase->type(address);
331 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
332
333 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
334 // Unsafe off-heap access with zero address. Remove access and other control users
335 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
336 assert(ctl != NULL, "unsafe accesses should be control dependent");
337 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
338 Node* u = ctl->fast_out(i);
339 if (u != ctl) {
340 igvn->rehash_node_delayed(u);
341 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
342 --i, imax -= nb;
343 }
344 }
345 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
346 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
347 phase->C->root()->add_req(halt);
348 return this;
349 }
350
351 if (can_reshape && igvn != NULL &&
352 (igvn->_worklist.member(address) ||
353 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
354 // The address's base and type may change when the address is processed.
355 // Delay this mem node transformation until the address is processed.
356 igvn->_worklist.push(this);
357 return NodeSentinel; // caller will return NULL
358 }
359
360 // Do NOT remove or optimize the next lines: ensure a new alias index
361 // is allocated for an oop pointer type before Escape Analysis.
362 // Note: C++ will not remove it since the call has side effect.
363 if (t_adr->isa_oopptr()) {
364 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
365 }
366
367 Node* base = NULL;
368 if (address->is_AddP()) {
369 base = address->in(AddPNode::Base);
370 }
371 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
372 !t_adr->isa_rawptr()) {
373 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
374 // Skip this node optimization if its address has TOP base.
375 return NodeSentinel; // caller will return NULL
376 }
377
378 // Avoid independent memory operations
379 Node* old_mem = mem;
380
381 // The code which unhooks non-raw memories from complete (macro-expanded)
382 // initializations was removed. After macro-expansion all stores catched
383 // by Initialize node became raw stores and there is no information
384 // which memory slices they modify. So it is unsafe to move any memory
385 // operation above these stores. Also in most cases hooked non-raw memories
386 // were already unhooked by using information from detect_ptr_independence()
387 // and find_previous_store().
388
389 if (mem->is_MergeMem()) {
390 MergeMemNode* mmem = mem->as_MergeMem();
391 const TypePtr *tp = t_adr->is_ptr();
392
393 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
394 }
395
396 if (mem != old_mem) {
397 set_req(MemNode::Memory, mem);
398 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
399 igvn->_worklist.push(old_mem);
400 }
401 if (phase->type(mem) == Type::TOP) return NodeSentinel;
402 return this;
403 }
404
405 // let the subclass continue analyzing...
406 return NULL;
407 }
408
409 // Helper function for proving some simple control dominations.
410 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
411 // Already assumes that 'dom' is available at 'sub', and that 'sub'
412 // is not a constant (dominated by the method's StartNode).
413 // Used by MemNode::find_previous_store to prove that the
414 // control input of a memory operation predates (dominates)
415 // an allocation it wants to look past.
416 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
417 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
418 return false; // Conservative answer for dead code
419
420 // Check 'dom'. Skip Proj and CatchProj nodes.
421 dom = dom->find_exact_control(dom);
422 if (dom == NULL || dom->is_top())
423 return false; // Conservative answer for dead code
424
425 if (dom == sub) {
426 // For the case when, for example, 'sub' is Initialize and the original
427 // 'dom' is Proj node of the 'sub'.
428 return false;
429 }
430
431 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
432 return true;
433
434 // 'dom' dominates 'sub' if its control edge and control edges
435 // of all its inputs dominate or equal to sub's control edge.
436
437 // Currently 'sub' is either Allocate, Initialize or Start nodes.
438 // Or Region for the check in LoadNode::Ideal();
439 // 'sub' should have sub->in(0) != NULL.
440 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
441 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
442
443 // Get control edge of 'sub'.
444 Node* orig_sub = sub;
445 sub = sub->find_exact_control(sub->in(0));
446 if (sub == NULL || sub->is_top())
447 return false; // Conservative answer for dead code
448
449 assert(sub->is_CFG(), "expecting control");
450
451 if (sub == dom)
452 return true;
453
454 if (sub->is_Start() || sub->is_Root())
455 return false;
456
457 {
458 // Check all control edges of 'dom'.
459
460 ResourceMark rm;
461 Node_List nlist;
462 Unique_Node_List dom_list;
463
464 dom_list.push(dom);
465 bool only_dominating_controls = false;
466
467 for (uint next = 0; next < dom_list.size(); next++) {
468 Node* n = dom_list.at(next);
469 if (n == orig_sub)
470 return false; // One of dom's inputs dominated by sub.
471 if (!n->is_CFG() && n->pinned()) {
472 // Check only own control edge for pinned non-control nodes.
473 n = n->find_exact_control(n->in(0));
474 if (n == NULL || n->is_top())
475 return false; // Conservative answer for dead code
476 assert(n->is_CFG(), "expecting control");
477 dom_list.push(n);
478 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
479 only_dominating_controls = true;
480 } else if (n->is_CFG()) {
481 if (n->dominates(sub, nlist))
482 only_dominating_controls = true;
483 else
484 return false;
485 } else {
486 // First, own control edge.
487 Node* m = n->find_exact_control(n->in(0));
488 if (m != NULL) {
489 if (m->is_top())
490 return false; // Conservative answer for dead code
491 dom_list.push(m);
492 }
493 // Now, the rest of edges.
494 uint cnt = n->req();
495 for (uint i = 1; i < cnt; i++) {
496 m = n->find_exact_control(n->in(i));
497 if (m == NULL || m->is_top())
498 continue;
499 dom_list.push(m);
500 }
501 }
502 }
503 return only_dominating_controls;
504 }
505 }
506
507 //---------------------detect_ptr_independence---------------------------------
508 // Used by MemNode::find_previous_store to prove that two base
509 // pointers are never equal.
510 // The pointers are accompanied by their associated allocations,
511 // if any, which have been previously discovered by the caller.
512 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
513 Node* p2, AllocateNode* a2,
514 PhaseTransform* phase) {
515 // Attempt to prove that these two pointers cannot be aliased.
516 // They may both manifestly be allocations, and they should differ.
517 // Or, if they are not both allocations, they can be distinct constants.
518 // Otherwise, one is an allocation and the other a pre-existing value.
519 if (a1 == NULL && a2 == NULL) { // neither an allocation
520 return (p1 != p2) && p1->is_Con() && p2->is_Con();
521 } else if (a1 != NULL && a2 != NULL) { // both allocations
522 return (a1 != a2);
523 } else if (a1 != NULL) { // one allocation a1
524 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
525 return all_controls_dominate(p2, a1);
526 } else { //(a2 != NULL) // one allocation a2
527 return all_controls_dominate(p1, a2);
528 }
529 return false;
530 }
531
532
533 // Find an arraycopy ac that produces the memory state represented by parameter mem.
534 // Return ac if
535 // (a) can_see_stored_value=true and ac must have set the value for this load or if
536 // (b) can_see_stored_value=false and ac could have set the value for this load or if
537 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
538 // In case (c) change the parameter mem to the memory input of ac to skip it
539 // when searching stored value.
540 // Otherwise return NULL.
541 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
542 ArrayCopyNode* ac = find_array_copy_clone(phase, ld_alloc, mem);
543 if (ac != NULL) {
544 Node* ld_addp = in(MemNode::Address);
545 Node* src = ac->in(ArrayCopyNode::Src);
546 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
547
548 // This is a load from a cloned array. The corresponding arraycopy ac must
549 // have set the value for the load and we can return ac but only if the load
550 // is known to be within bounds. This is checked below.
551 if (ary_t != NULL && ld_addp->is_AddP()) {
552 Node* ld_offs = ld_addp->in(AddPNode::Offset);
553 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
554 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
555 jlong elemsize = type2aelembytes(ary_elem);
556
557 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
558 const TypeInt* sizetype = ary_t->size();
559
560 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
561 // The load is known to be within bounds. It receives its value from ac.
562 return ac;
563 }
564 // The load is known to be out-of-bounds.
565 }
566 // The load could be out-of-bounds. It must not be hoisted but must remain
567 // dependent on the runtime range check. This is achieved by returning NULL.
568 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
569 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
570
571 if (ac->is_arraycopy_validated() ||
572 ac->is_copyof_validated() ||
573 ac->is_copyofrange_validated()) {
574 Node* ld_addp = in(MemNode::Address);
575 if (ld_addp->is_AddP()) {
576 Node* ld_base = ld_addp->in(AddPNode::Address);
577 Node* ld_offs = ld_addp->in(AddPNode::Offset);
578
579 Node* dest = ac->in(ArrayCopyNode::Dest);
580
581 if (dest == ld_base) {
582 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
583 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
584 return ac;
585 }
586 if (!can_see_stored_value) {
587 mem = ac->in(TypeFunc::Memory);
588 return ac;
589 }
590 }
591 }
592 }
593 }
594 return NULL;
595 }
596
597 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseTransform* phase, Node* ld_alloc, Node* mem) const {
598 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
599 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
600 if (ld_alloc != NULL) {
601 // Check if there is an array copy for a clone
602 Node* mb = mem->in(0);
603 ArrayCopyNode* ac = NULL;
604 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
605 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
606 ac = mb->in(0)->in(0)->as_ArrayCopy();
607 } else {
608 // Step over GC barrier when ReduceInitialCardMarks is disabled
609 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
610 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
611
612 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
613 ac = control_proj_ac->in(0)->as_ArrayCopy();
614 }
615 }
616
617 if (ac != NULL && ac->is_clonebasic()) {
618 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase);
619 if (alloc != NULL && alloc == ld_alloc) {
620 return ac;
621 }
622 }
623 }
624 }
625 return NULL;
626 }
627
628 // The logic for reordering loads and stores uses four steps:
629 // (a) Walk carefully past stores and initializations which we
630 // can prove are independent of this load.
631 // (b) Observe that the next memory state makes an exact match
632 // with self (load or store), and locate the relevant store.
633 // (c) Ensure that, if we were to wire self directly to the store,
634 // the optimizer would fold it up somehow.
635 // (d) Do the rewiring, and return, depending on some other part of
636 // the optimizer to fold up the load.
637 // This routine handles steps (a) and (b). Steps (c) and (d) are
638 // specific to loads and stores, so they are handled by the callers.
639 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
640 //
641 Node* MemNode::find_previous_store(PhaseTransform* phase) {
642 Node* ctrl = in(MemNode::Control);
643 Node* adr = in(MemNode::Address);
644 intptr_t offset = 0;
645 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
646 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
647
648 if (offset == Type::OffsetBot)
649 return NULL; // cannot unalias unless there are precise offsets
650
651 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
652 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
653
654 intptr_t size_in_bytes = memory_size();
655
656 Node* mem = in(MemNode::Memory); // start searching here...
657
658 int cnt = 50; // Cycle limiter
659 for (;;) { // While we can dance past unrelated stores...
660 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
661
662 Node* prev = mem;
663 if (mem->is_Store()) {
664 Node* st_adr = mem->in(MemNode::Address);
665 intptr_t st_offset = 0;
666 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
667 if (st_base == NULL)
668 break; // inscrutable pointer
669
670 // For raw accesses it's not enough to prove that constant offsets don't intersect.
671 // We need the bases to be the equal in order for the offset check to make sense.
672 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
673 break;
674 }
675
676 if (st_offset != offset && st_offset != Type::OffsetBot) {
677 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
678 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
679 if (st_offset >= offset + size_in_bytes ||
680 st_offset <= offset - MAX_STORE ||
681 st_offset <= offset - mem->as_Store()->memory_size()) {
682 // Success: The offsets are provably independent.
683 // (You may ask, why not just test st_offset != offset and be done?
684 // The answer is that stores of different sizes can co-exist
685 // in the same sequence of RawMem effects. We sometimes initialize
686 // a whole 'tile' of array elements with a single jint or jlong.)
687 mem = mem->in(MemNode::Memory);
688 continue; // (a) advance through independent store memory
689 }
690 }
691 if (st_base != base &&
692 detect_ptr_independence(base, alloc,
693 st_base,
694 AllocateNode::Ideal_allocation(st_base, phase),
695 phase)) {
696 // Success: The bases are provably independent.
697 mem = mem->in(MemNode::Memory);
698 continue; // (a) advance through independent store memory
699 }
700
701 // (b) At this point, if the bases or offsets do not agree, we lose,
702 // since we have not managed to prove 'this' and 'mem' independent.
703 if (st_base == base && st_offset == offset) {
704 return mem; // let caller handle steps (c), (d)
705 }
706
707 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
708 InitializeNode* st_init = mem->in(0)->as_Initialize();
709 AllocateNode* st_alloc = st_init->allocation();
710 if (st_alloc == NULL)
711 break; // something degenerated
712 bool known_identical = false;
713 bool known_independent = false;
714 if (alloc == st_alloc)
715 known_identical = true;
716 else if (alloc != NULL)
717 known_independent = true;
718 else if (all_controls_dominate(this, st_alloc))
719 known_independent = true;
720
721 if (known_independent) {
722 // The bases are provably independent: Either they are
723 // manifestly distinct allocations, or else the control
724 // of this load dominates the store's allocation.
725 int alias_idx = phase->C->get_alias_index(adr_type());
726 if (alias_idx == Compile::AliasIdxRaw) {
727 mem = st_alloc->in(TypeFunc::Memory);
728 } else {
729 mem = st_init->memory(alias_idx);
730 }
731 continue; // (a) advance through independent store memory
732 }
733
734 // (b) at this point, if we are not looking at a store initializing
735 // the same allocation we are loading from, we lose.
736 if (known_identical) {
737 // From caller, can_see_stored_value will consult find_captured_store.
738 return mem; // let caller handle steps (c), (d)
739 }
740
741 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
742 if (prev != mem) {
743 // Found an arraycopy but it doesn't affect that load
744 continue;
745 }
746 // Found an arraycopy that may affect that load
747 return mem;
748 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
749 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
750 if (mem->is_Proj() && mem->in(0)->is_Call()) {
751 // ArrayCopyNodes processed here as well.
752 CallNode *call = mem->in(0)->as_Call();
753 if (!call->may_modify(addr_t, phase)) {
754 mem = call->in(TypeFunc::Memory);
755 continue; // (a) advance through independent call memory
756 }
757 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
758 ArrayCopyNode* ac = NULL;
759 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
760 break;
761 }
762 mem = mem->in(0)->in(TypeFunc::Memory);
763 continue; // (a) advance through independent MemBar memory
764 } else if (mem->is_ClearArray()) {
765 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
766 // (the call updated 'mem' value)
767 continue; // (a) advance through independent allocation memory
768 } else {
769 // Can not bypass initialization of the instance
770 // we are looking for.
771 return mem;
772 }
773 } else if (mem->is_MergeMem()) {
774 int alias_idx = phase->C->get_alias_index(adr_type());
775 mem = mem->as_MergeMem()->memory_at(alias_idx);
776 continue; // (a) advance through independent MergeMem memory
777 }
778 }
779
780 // Unless there is an explicit 'continue', we must bail out here,
781 // because 'mem' is an inscrutable memory state (e.g., a call).
782 break;
783 }
784
785 return NULL; // bail out
786 }
787
788 //----------------------calculate_adr_type-------------------------------------
789 // Helper function. Notices when the given type of address hits top or bottom.
790 // Also, asserts a cross-check of the type against the expected address type.
791 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
792 if (t == Type::TOP) return NULL; // does not touch memory any more?
793 #ifdef ASSERT
794 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
795 #endif
796 const TypePtr* tp = t->isa_ptr();
797 if (tp == NULL) {
798 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
799 return TypePtr::BOTTOM; // touches lots of memory
800 } else {
801 #ifdef ASSERT
802 // %%%% [phh] We don't check the alias index if cross_check is
803 // TypeRawPtr::BOTTOM. Needs to be investigated.
804 if (cross_check != NULL &&
805 cross_check != TypePtr::BOTTOM &&
806 cross_check != TypeRawPtr::BOTTOM) {
807 // Recheck the alias index, to see if it has changed (due to a bug).
808 Compile* C = Compile::current();
809 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
810 "must stay in the original alias category");
811 // The type of the address must be contained in the adr_type,
812 // disregarding "null"-ness.
813 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
814 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
815 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
816 "real address must not escape from expected memory type");
817 }
818 #endif
819 return tp;
820 }
821 }
822
823 //=============================================================================
824 // Should LoadNode::Ideal() attempt to remove control edges?
825 bool LoadNode::can_remove_control() const {
826 return !has_pinned_control_dependency();
827 }
828 uint LoadNode::size_of() const { return sizeof(*this); }
829 bool LoadNode::cmp( const Node &n ) const
830 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
831 const Type *LoadNode::bottom_type() const { return _type; }
832 uint LoadNode::ideal_reg() const {
833 return _type->ideal_reg();
834 }
835
836 #ifndef PRODUCT
837 void LoadNode::dump_spec(outputStream *st) const {
838 MemNode::dump_spec(st);
839 if( !Verbose && !WizardMode ) {
840 // standard dump does this in Verbose and WizardMode
841 st->print(" #"); _type->dump_on(st);
842 }
843 if (!depends_only_on_test()) {
844 st->print(" (does not depend only on test, ");
845 if (control_dependency() == UnknownControl) {
846 st->print("unknown control");
847 } else if (control_dependency() == Pinned) {
848 st->print("pinned");
849 } else if (adr_type() == TypeRawPtr::BOTTOM) {
850 st->print("raw access");
851 } else {
852 st->print("unknown reason");
853 }
854 st->print(")");
855 }
856 }
857 #endif
858
859 #ifdef ASSERT
860 //----------------------------is_immutable_value-------------------------------
861 // Helper function to allow a raw load without control edge for some cases
862 bool LoadNode::is_immutable_value(Node* adr) {
863 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
864 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
865 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
866 in_bytes(JavaThread::osthread_offset()) ||
867 adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
868 in_bytes(JavaThread::threadObj_offset())));
869 }
870 #endif
871
872 //----------------------------LoadNode::make-----------------------------------
873 // Polymorphic factory method:
874 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
875 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
876 Compile* C = gvn.C;
877
878 // sanity check the alias category against the created node type
879 assert(!(adr_type->isa_oopptr() &&
880 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
881 "use LoadKlassNode instead");
882 assert(!(adr_type->isa_aryptr() &&
883 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
884 "use LoadRangeNode instead");
885 // Check control edge of raw loads
886 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
887 // oop will be recorded in oop map if load crosses safepoint
888 rt->isa_oopptr() || is_immutable_value(adr),
889 "raw memory operations should have control edge");
890 LoadNode* load = NULL;
891 switch (bt) {
892 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
893 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
894 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
895 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
896 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
897 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
898 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
899 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
900 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
901 case T_OBJECT:
902 #ifdef _LP64
903 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
904 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
905 } else
906 #endif
907 {
908 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
909 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
910 }
911 break;
912 default:
913 ShouldNotReachHere();
914 break;
915 }
916 assert(load != NULL, "LoadNode should have been created");
917 if (unaligned) {
918 load->set_unaligned_access();
919 }
920 if (mismatched) {
921 load->set_mismatched_access();
922 }
923 if (unsafe) {
924 load->set_unsafe_access();
925 }
926 load->set_barrier_data(barrier_data);
927 if (load->Opcode() == Op_LoadN) {
928 Node* ld = gvn.transform(load);
929 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
930 }
931
932 return load;
933 }
934
935 //------------------------------hash-------------------------------------------
936 uint LoadNode::hash() const {
937 // unroll addition of interesting fields
938 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
939 }
940
941 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
942 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
943 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
944 bool is_stable_ary = FoldStableValues &&
945 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
946 tp->isa_aryptr()->is_stable();
947
948 return (eliminate_boxing && non_volatile) || is_stable_ary;
949 }
950
951 return false;
952 }
953
954 // Is the value loaded previously stored by an arraycopy? If so return
955 // a load node that reads from the source array so we may be able to
956 // optimize out the ArrayCopy node later.
957 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
958 Node* ld_adr = in(MemNode::Address);
959 intptr_t ld_off = 0;
960 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
961 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
962 if (ac != NULL) {
963 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
964
965 Node* mem = ac->in(TypeFunc::Memory);
966 Node* ctl = ac->in(0);
967 Node* src = ac->in(ArrayCopyNode::Src);
968
969 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
970 return NULL;
971 }
972
973 LoadNode* ld = clone()->as_Load();
974 Node* addp = in(MemNode::Address)->clone();
975 if (ac->as_ArrayCopy()->is_clonebasic()) {
976 assert(ld_alloc != NULL, "need an alloc");
977 assert(addp->is_AddP(), "address must be addp");
978 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
979 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
980 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
981 addp->set_req(AddPNode::Base, src);
982 addp->set_req(AddPNode::Address, src);
983 } else {
984 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
985 ac->as_ArrayCopy()->is_copyof_validated() ||
986 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
987 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
988 addp->set_req(AddPNode::Base, src);
989 addp->set_req(AddPNode::Address, src);
990
991 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
992 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
993 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
994 uint shift = exact_log2(type2aelembytes(ary_elem));
995
996 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
997 #ifdef _LP64
998 diff = phase->transform(new ConvI2LNode(diff));
999 #endif
1000 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1001
1002 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1003 addp->set_req(AddPNode::Offset, offset);
1004 }
1005 addp = phase->transform(addp);
1006 #ifdef ASSERT
1007 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1008 ld->_adr_type = adr_type;
1009 #endif
1010 ld->set_req(MemNode::Address, addp);
1011 ld->set_req(0, ctl);
1012 ld->set_req(MemNode::Memory, mem);
1013 // load depends on the tests that validate the arraycopy
1014 ld->_control_dependency = UnknownControl;
1015 return ld;
1016 }
1017 return NULL;
1018 }
1019
1020
1021 //---------------------------can_see_stored_value------------------------------
1022 // This routine exists to make sure this set of tests is done the same
1023 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1024 // will change the graph shape in a way which makes memory alive twice at the
1025 // same time (uses the Oracle model of aliasing), then some
1026 // LoadXNode::Identity will fold things back to the equivalence-class model
1027 // of aliasing.
1028 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1029 Node* ld_adr = in(MemNode::Address);
1030 intptr_t ld_off = 0;
1031 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1032 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1033 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1034 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1035 // This is more general than load from boxing objects.
1036 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1037 uint alias_idx = atp->index();
1038 Node* result = NULL;
1039 Node* current = st;
1040 // Skip through chains of MemBarNodes checking the MergeMems for
1041 // new states for the slice of this load. Stop once any other
1042 // kind of node is encountered. Loads from final memory can skip
1043 // through any kind of MemBar but normal loads shouldn't skip
1044 // through MemBarAcquire since the could allow them to move out of
1045 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1046 // because alias info above them may be inaccurate (e.g., due to
1047 // mixed/mismatched unsafe accesses).
1048 bool is_final_mem = !atp->is_rewritable();
1049 while (current->is_Proj()) {
1050 int opc = current->in(0)->Opcode();
1051 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1052 opc == Op_MemBarAcquireLock ||
1053 opc == Op_LoadFence)) ||
1054 opc == Op_MemBarRelease ||
1055 opc == Op_StoreFence ||
1056 opc == Op_MemBarReleaseLock ||
1057 opc == Op_MemBarStoreStore ||
1058 opc == Op_StoreStoreFence) {
1059 Node* mem = current->in(0)->in(TypeFunc::Memory);
1060 if (mem->is_MergeMem()) {
1061 MergeMemNode* merge = mem->as_MergeMem();
1062 Node* new_st = merge->memory_at(alias_idx);
1063 if (new_st == merge->base_memory()) {
1064 // Keep searching
1065 current = new_st;
1066 continue;
1067 }
1068 // Save the new memory state for the slice and fall through
1069 // to exit.
1070 result = new_st;
1071 }
1072 }
1073 break;
1074 }
1075 if (result != NULL) {
1076 st = result;
1077 }
1078 }
1079
1080 // Loop around twice in the case Load -> Initialize -> Store.
1081 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1082 for (int trip = 0; trip <= 1; trip++) {
1083
1084 if (st->is_Store()) {
1085 Node* st_adr = st->in(MemNode::Address);
1086 if (st_adr != ld_adr) {
1087 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1088 intptr_t st_off = 0;
1089 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1090 if (ld_base == NULL) return NULL;
1091 if (st_base == NULL) return NULL;
1092 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL;
1093 if (ld_off != st_off) return NULL;
1094 if (ld_off == Type::OffsetBot) return NULL;
1095 // Same base, same offset.
1096 // Possible improvement for arrays: check index value instead of absolute offset.
1097
1098 // At this point we have proven something like this setup:
1099 // B = << base >>
1100 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1101 // S = StoreQ(AddP( B , #Off), V)
1102 // (Actually, we haven't yet proven the Q's are the same.)
1103 // In other words, we are loading from a casted version of
1104 // the same pointer-and-offset that we stored to.
1105 // Casted version may carry a dependency and it is respected.
1106 // Thus, we are able to replace L by V.
1107 }
1108 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1109 if (store_Opcode() != st->Opcode()) {
1110 return NULL;
1111 }
1112 // LoadVector/StoreVector needs additional check to ensure the types match.
1113 if (store_Opcode() == Op_StoreVector) {
1114 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1115 const TypeVect* out_vt = as_LoadVector()->vect_type();
1116 if (in_vt != out_vt) {
1117 return NULL;
1118 }
1119 }
1120 return st->in(MemNode::ValueIn);
1121 }
1122
1123 // A load from a freshly-created object always returns zero.
1124 // (This can happen after LoadNode::Ideal resets the load's memory input
1125 // to find_captured_store, which returned InitializeNode::zero_memory.)
1126 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1127 (st->in(0) == ld_alloc) &&
1128 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1129 // return a zero value for the load's basic type
1130 // (This is one of the few places where a generic PhaseTransform
1131 // can create new nodes. Think of it as lazily manifesting
1132 // virtually pre-existing constants.)
1133 if (memory_type() != T_VOID) {
1134 if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == NULL) {
1135 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1136 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1137 // by the ArrayCopyNode.
1138 return phase->zerocon(memory_type());
1139 }
1140 } else {
1141 // TODO: materialize all-zero vector constant
1142 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1143 }
1144 }
1145
1146 // A load from an initialization barrier can match a captured store.
1147 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1148 InitializeNode* init = st->in(0)->as_Initialize();
1149 AllocateNode* alloc = init->allocation();
1150 if ((alloc != NULL) && (alloc == ld_alloc)) {
1151 // examine a captured store value
1152 st = init->find_captured_store(ld_off, memory_size(), phase);
1153 if (st != NULL) {
1154 continue; // take one more trip around
1155 }
1156 }
1157 }
1158
1159 // Load boxed value from result of valueOf() call is input parameter.
1160 if (this->is_Load() && ld_adr->is_AddP() &&
1161 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1162 intptr_t ignore = 0;
1163 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1164 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1165 base = bs->step_over_gc_barrier(base);
1166 if (base != NULL && base->is_Proj() &&
1167 base->as_Proj()->_con == TypeFunc::Parms &&
1168 base->in(0)->is_CallStaticJava() &&
1169 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1170 return base->in(0)->in(TypeFunc::Parms);
1171 }
1172 }
1173
1174 break;
1175 }
1176
1177 return NULL;
1178 }
1179
1180 //----------------------is_instance_field_load_with_local_phi------------------
1181 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1182 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1183 in(Address)->is_AddP() ) {
1184 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1185 // Only instances and boxed values.
1186 if( t_oop != NULL &&
1187 (t_oop->is_ptr_to_boxed_value() ||
1188 t_oop->is_known_instance_field()) &&
1189 t_oop->offset() != Type::OffsetBot &&
1190 t_oop->offset() != Type::OffsetTop) {
1191 return true;
1192 }
1193 }
1194 return false;
1195 }
1196
1197 //------------------------------Identity---------------------------------------
1198 // Loads are identity if previous store is to same address
1199 Node* LoadNode::Identity(PhaseGVN* phase) {
1200 // If the previous store-maker is the right kind of Store, and the store is
1201 // to the same address, then we are equal to the value stored.
1202 Node* mem = in(Memory);
1203 Node* value = can_see_stored_value(mem, phase);
1204 if( value ) {
1205 // byte, short & char stores truncate naturally.
1206 // A load has to load the truncated value which requires
1207 // some sort of masking operation and that requires an
1208 // Ideal call instead of an Identity call.
1209 if (memory_size() < BytesPerInt) {
1210 // If the input to the store does not fit with the load's result type,
1211 // it must be truncated via an Ideal call.
1212 if (!phase->type(value)->higher_equal(phase->type(this)))
1213 return this;
1214 }
1215 // (This works even when value is a Con, but LoadNode::Value
1216 // usually runs first, producing the singleton type of the Con.)
1217 if (!has_pinned_control_dependency() || value->is_Con()) {
1218 return value;
1219 } else {
1220 return this;
1221 }
1222 }
1223
1224 if (has_pinned_control_dependency()) {
1225 return this;
1226 }
1227 // Search for an existing data phi which was generated before for the same
1228 // instance's field to avoid infinite generation of phis in a loop.
1229 Node *region = mem->in(0);
1230 if (is_instance_field_load_with_local_phi(region)) {
1231 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1232 int this_index = phase->C->get_alias_index(addr_t);
1233 int this_offset = addr_t->offset();
1234 int this_iid = addr_t->instance_id();
1235 if (!addr_t->is_known_instance() &&
1236 addr_t->is_ptr_to_boxed_value()) {
1237 // Use _idx of address base (could be Phi node) for boxed values.
1238 intptr_t ignore = 0;
1239 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1240 if (base == NULL) {
1241 return this;
1242 }
1243 this_iid = base->_idx;
1244 }
1245 const Type* this_type = bottom_type();
1246 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1247 Node* phi = region->fast_out(i);
1248 if (phi->is_Phi() && phi != mem &&
1249 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1250 return phi;
1251 }
1252 }
1253 }
1254
1255 return this;
1256 }
1257
1258 // Construct an equivalent unsigned load.
1259 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1260 BasicType bt = T_ILLEGAL;
1261 const Type* rt = NULL;
1262 switch (Opcode()) {
1263 case Op_LoadUB: return this;
1264 case Op_LoadUS: return this;
1265 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1266 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1267 default:
1268 assert(false, "no unsigned variant: %s", Name());
1269 return NULL;
1270 }
1271 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1272 raw_adr_type(), rt, bt, _mo, _control_dependency,
1273 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1274 }
1275
1276 // Construct an equivalent signed load.
1277 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1278 BasicType bt = T_ILLEGAL;
1279 const Type* rt = NULL;
1280 switch (Opcode()) {
1281 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1282 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1283 case Op_LoadB: // fall through
1284 case Op_LoadS: // fall through
1285 case Op_LoadI: // fall through
1286 case Op_LoadL: return this;
1287 default:
1288 assert(false, "no signed variant: %s", Name());
1289 return NULL;
1290 }
1291 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1292 raw_adr_type(), rt, bt, _mo, _control_dependency,
1293 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1294 }
1295
1296 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1297 BasicType bt = rt->basic_type();
1298 switch (Opcode()) {
1299 case Op_LoadI: return (bt == T_FLOAT);
1300 case Op_LoadL: return (bt == T_DOUBLE);
1301 case Op_LoadF: return (bt == T_INT);
1302 case Op_LoadD: return (bt == T_LONG);
1303
1304 default: return false;
1305 }
1306 }
1307
1308 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1309 BasicType bt = rt->basic_type();
1310 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1311 bool is_mismatched = is_mismatched_access();
1312 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1313 if (raw_type == NULL) {
1314 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1315 }
1316 const int op = Opcode();
1317 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1318 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1319 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1320 raw_adr_type(), rt, bt, _mo, _control_dependency,
1321 require_atomic_access, is_unaligned_access(), is_mismatched);
1322 }
1323
1324 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1325 BasicType bt = vt->basic_type();
1326 switch (Opcode()) {
1327 case Op_StoreI: return (bt == T_FLOAT);
1328 case Op_StoreL: return (bt == T_DOUBLE);
1329 case Op_StoreF: return (bt == T_INT);
1330 case Op_StoreD: return (bt == T_LONG);
1331
1332 default: return false;
1333 }
1334 }
1335
1336 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1337 BasicType bt = vt->basic_type();
1338 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1339 const int op = Opcode();
1340 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1341 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1342 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1343 raw_adr_type(), val, bt, _mo, require_atomic_access);
1344
1345 bool is_mismatched = is_mismatched_access();
1346 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1347 if (raw_type == NULL) {
1348 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1349 }
1350 if (is_mismatched) {
1351 st->set_mismatched_access();
1352 }
1353 return st;
1354 }
1355
1356 // We're loading from an object which has autobox behaviour.
1357 // If this object is result of a valueOf call we'll have a phi
1358 // merging a newly allocated object and a load from the cache.
1359 // We want to replace this load with the original incoming
1360 // argument to the valueOf call.
1361 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1362 assert(igvn->C->eliminate_boxing(), "sanity");
1363 intptr_t ignore = 0;
1364 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1365 if ((base == NULL) || base->is_Phi()) {
1366 // Push the loads from the phi that comes from valueOf up
1367 // through it to allow elimination of the loads and the recovery
1368 // of the original value. It is done in split_through_phi().
1369 return NULL;
1370 } else if (base->is_Load() ||
1371 (base->is_DecodeN() && base->in(1)->is_Load())) {
1372 // Eliminate the load of boxed value for integer types from the cache
1373 // array by deriving the value from the index into the array.
1374 // Capture the offset of the load and then reverse the computation.
1375
1376 // Get LoadN node which loads a boxing object from 'cache' array.
1377 if (base->is_DecodeN()) {
1378 base = base->in(1);
1379 }
1380 if (!base->in(Address)->is_AddP()) {
1381 return NULL; // Complex address
1382 }
1383 AddPNode* address = base->in(Address)->as_AddP();
1384 Node* cache_base = address->in(AddPNode::Base);
1385 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1386 // Get ConP node which is static 'cache' field.
1387 cache_base = cache_base->in(1);
1388 }
1389 if ((cache_base != NULL) && cache_base->is_Con()) {
1390 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1391 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1392 Node* elements[4];
1393 int shift = exact_log2(type2aelembytes(T_OBJECT));
1394 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1395 if (count > 0 && elements[0]->is_Con() &&
1396 (count == 1 ||
1397 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1398 elements[1]->in(2) == igvn->intcon(shift)))) {
1399 ciObjArray* array = base_type->const_oop()->as_obj_array();
1400 // Fetch the box object cache[0] at the base of the array and get its value
1401 ciInstance* box = array->obj_at(0)->as_instance();
1402 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1403 assert(ik->is_box_klass(), "sanity");
1404 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1405 if (ik->nof_nonstatic_fields() == 1) {
1406 // This should be true nonstatic_field_at requires calling
1407 // nof_nonstatic_fields so check it anyway
1408 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1409 BasicType bt = c.basic_type();
1410 // Only integer types have boxing cache.
1411 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1412 bt == T_BYTE || bt == T_SHORT ||
1413 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1414 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1415 if (cache_low != (int)cache_low) {
1416 return NULL; // should not happen since cache is array indexed by value
1417 }
1418 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1419 if (offset != (int)offset) {
1420 return NULL; // should not happen since cache is array indexed by value
1421 }
1422 // Add up all the offsets making of the address of the load
1423 Node* result = elements[0];
1424 for (int i = 1; i < count; i++) {
1425 result = igvn->transform(new AddXNode(result, elements[i]));
1426 }
1427 // Remove the constant offset from the address and then
1428 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1429 // remove the scaling of the offset to recover the original index.
1430 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1431 // Peel the shift off directly but wrap it in a dummy node
1432 // since Ideal can't return existing nodes
1433 igvn->_worklist.push(result); // remove dead node later
1434 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1435 } else if (result->is_Add() && result->in(2)->is_Con() &&
1436 result->in(1)->Opcode() == Op_LShiftX &&
1437 result->in(1)->in(2) == igvn->intcon(shift)) {
1438 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1439 // but for boxing cache access we know that X<<Z will not overflow
1440 // (there is range check) so we do this optimizatrion by hand here.
1441 igvn->_worklist.push(result); // remove dead node later
1442 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1443 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1444 } else {
1445 result = new RShiftXNode(result, igvn->intcon(shift));
1446 }
1447 #ifdef _LP64
1448 if (bt != T_LONG) {
1449 result = new ConvL2INode(igvn->transform(result));
1450 }
1451 #else
1452 if (bt == T_LONG) {
1453 result = new ConvI2LNode(igvn->transform(result));
1454 }
1455 #endif
1456 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1457 // Need to preserve unboxing load type if it is unsigned.
1458 switch(this->Opcode()) {
1459 case Op_LoadUB:
1460 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1461 break;
1462 case Op_LoadUS:
1463 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1464 break;
1465 }
1466 return result;
1467 }
1468 }
1469 }
1470 }
1471 }
1472 return NULL;
1473 }
1474
1475 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1476 Node* region = phi->in(0);
1477 if (region == NULL) {
1478 return false; // Wait stable graph
1479 }
1480 uint cnt = phi->req();
1481 for (uint i = 1; i < cnt; i++) {
1482 Node* rc = region->in(i);
1483 if (rc == NULL || phase->type(rc) == Type::TOP)
1484 return false; // Wait stable graph
1485 Node* in = phi->in(i);
1486 if (in == NULL || phase->type(in) == Type::TOP)
1487 return false; // Wait stable graph
1488 }
1489 return true;
1490 }
1491 //------------------------------split_through_phi------------------------------
1492 // Split instance or boxed field load through Phi.
1493 Node* LoadNode::split_through_phi(PhaseGVN* phase) {
1494 if (req() > 3) {
1495 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1496 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1497 return NULL;
1498 }
1499 Node* mem = in(Memory);
1500 Node* address = in(Address);
1501 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1502
1503 assert((t_oop != NULL) &&
1504 (t_oop->is_known_instance_field() ||
1505 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1506
1507 Compile* C = phase->C;
1508 intptr_t ignore = 0;
1509 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1510 bool base_is_phi = (base != NULL) && base->is_Phi();
1511 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1512 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1513 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1514
1515 if (!((mem->is_Phi() || base_is_phi) &&
1516 (load_boxed_values || t_oop->is_known_instance_field()))) {
1517 return NULL; // memory is not Phi
1518 }
1519
1520 if (mem->is_Phi()) {
1521 if (!stable_phi(mem->as_Phi(), phase)) {
1522 return NULL; // Wait stable graph
1523 }
1524 uint cnt = mem->req();
1525 // Check for loop invariant memory.
1526 if (cnt == 3) {
1527 for (uint i = 1; i < cnt; i++) {
1528 Node* in = mem->in(i);
1529 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1530 if (m == mem) {
1531 if (i == 1) {
1532 // if the first edge was a loop, check second edge too.
1533 // If both are replaceable - we are in an infinite loop
1534 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1535 if (n == mem) {
1536 break;
1537 }
1538 }
1539 set_req(Memory, mem->in(cnt - i));
1540 return this; // made change
1541 }
1542 }
1543 }
1544 }
1545 if (base_is_phi) {
1546 if (!stable_phi(base->as_Phi(), phase)) {
1547 return NULL; // Wait stable graph
1548 }
1549 uint cnt = base->req();
1550 // Check for loop invariant memory.
1551 if (cnt == 3) {
1552 for (uint i = 1; i < cnt; i++) {
1553 if (base->in(i) == base) {
1554 return NULL; // Wait stable graph
1555 }
1556 }
1557 }
1558 }
1559
1560 // Split through Phi (see original code in loopopts.cpp).
1561 assert(C->have_alias_type(t_oop), "instance should have alias type");
1562
1563 // Do nothing here if Identity will find a value
1564 // (to avoid infinite chain of value phis generation).
1565 if (this != Identity(phase)) {
1566 return NULL;
1567 }
1568
1569 // Select Region to split through.
1570 Node* region;
1571 if (!base_is_phi) {
1572 assert(mem->is_Phi(), "sanity");
1573 region = mem->in(0);
1574 // Skip if the region dominates some control edge of the address.
1575 if (!MemNode::all_controls_dominate(address, region))
1576 return NULL;
1577 } else if (!mem->is_Phi()) {
1578 assert(base_is_phi, "sanity");
1579 region = base->in(0);
1580 // Skip if the region dominates some control edge of the memory.
1581 if (!MemNode::all_controls_dominate(mem, region))
1582 return NULL;
1583 } else if (base->in(0) != mem->in(0)) {
1584 assert(base_is_phi && mem->is_Phi(), "sanity");
1585 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1586 region = base->in(0);
1587 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1588 region = mem->in(0);
1589 } else {
1590 return NULL; // complex graph
1591 }
1592 } else {
1593 assert(base->in(0) == mem->in(0), "sanity");
1594 region = mem->in(0);
1595 }
1596
1597 const Type* this_type = this->bottom_type();
1598 int this_index = C->get_alias_index(t_oop);
1599 int this_offset = t_oop->offset();
1600 int this_iid = t_oop->instance_id();
1601 if (!t_oop->is_known_instance() && load_boxed_values) {
1602 // Use _idx of address base for boxed values.
1603 this_iid = base->_idx;
1604 }
1605 PhaseIterGVN* igvn = phase->is_IterGVN();
1606 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1607 for (uint i = 1; i < region->req(); i++) {
1608 Node* x;
1609 Node* the_clone = NULL;
1610 Node* in = region->in(i);
1611 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1612 in != NULL && in->is_OuterStripMinedLoop()) {
1613 // No node should go in the outer strip mined loop
1614 in = in->in(LoopNode::EntryControl);
1615 }
1616 if (in == NULL || in == C->top()) {
1617 x = C->top(); // Dead path? Use a dead data op
1618 } else {
1619 x = this->clone(); // Else clone up the data op
1620 the_clone = x; // Remember for possible deletion.
1621 // Alter data node to use pre-phi inputs
1622 if (this->in(0) == region) {
1623 x->set_req(0, in);
1624 } else {
1625 x->set_req(0, NULL);
1626 }
1627 if (mem->is_Phi() && (mem->in(0) == region)) {
1628 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1629 }
1630 if (address->is_Phi() && address->in(0) == region) {
1631 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1632 }
1633 if (base_is_phi && (base->in(0) == region)) {
1634 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1635 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1636 x->set_req(Address, adr_x);
1637 }
1638 }
1639 // Check for a 'win' on some paths
1640 const Type *t = x->Value(igvn);
1641
1642 bool singleton = t->singleton();
1643
1644 // See comments in PhaseIdealLoop::split_thru_phi().
1645 if (singleton && t == Type::TOP) {
1646 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1647 }
1648
1649 if (singleton) {
1650 x = igvn->makecon(t);
1651 } else {
1652 // We now call Identity to try to simplify the cloned node.
1653 // Note that some Identity methods call phase->type(this).
1654 // Make sure that the type array is big enough for
1655 // our new node, even though we may throw the node away.
1656 // (This tweaking with igvn only works because x is a new node.)
1657 igvn->set_type(x, t);
1658 // If x is a TypeNode, capture any more-precise type permanently into Node
1659 // otherwise it will be not updated during igvn->transform since
1660 // igvn->type(x) is set to x->Value() already.
1661 x->raise_bottom_type(t);
1662 Node* y = x->Identity(igvn);
1663 if (y != x) {
1664 x = y;
1665 } else {
1666 y = igvn->hash_find_insert(x);
1667 if (y) {
1668 x = y;
1669 } else {
1670 // Else x is a new node we are keeping
1671 // We do not need register_new_node_with_optimizer
1672 // because set_type has already been called.
1673 igvn->_worklist.push(x);
1674 }
1675 }
1676 }
1677 if (x != the_clone && the_clone != NULL) {
1678 igvn->remove_dead_node(the_clone);
1679 }
1680 phi->set_req(i, x);
1681 }
1682 // Record Phi
1683 igvn->register_new_node_with_optimizer(phi);
1684 return phi;
1685 }
1686
1687 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1688 if (Opcode() == Op_LoadX) {
1689 Node* address = in(MemNode::Address);
1690 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1691 Node* mem = in(MemNode::Memory);
1692 if (alloc != NULL && mem->is_Proj() &&
1693 mem->in(0) != NULL &&
1694 mem->in(0) == alloc->initialization() &&
1695 alloc->initialization()->proj_out_or_null(0) != NULL) {
1696 return alloc;
1697 }
1698 }
1699 return NULL;
1700 }
1701
1702
1703 //------------------------------Ideal------------------------------------------
1704 // If the load is from Field memory and the pointer is non-null, it might be possible to
1705 // zero out the control input.
1706 // If the offset is constant and the base is an object allocation,
1707 // try to hook me up to the exact initializing store.
1708 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1709 if (has_pinned_control_dependency()) {
1710 return NULL;
1711 }
1712 Node* p = MemNode::Ideal_common(phase, can_reshape);
1713 if (p) return (p == NodeSentinel) ? NULL : p;
1714
1715 Node* ctrl = in(MemNode::Control);
1716 Node* address = in(MemNode::Address);
1717 bool progress = false;
1718
1719 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1720 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1721
1722 // Skip up past a SafePoint control. Cannot do this for Stores because
1723 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1724 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1725 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1726 !addr_mark &&
1727 (depends_only_on_test() || has_unknown_control_dependency())) {
1728 ctrl = ctrl->in(0);
1729 set_req(MemNode::Control,ctrl);
1730 progress = true;
1731 }
1732
1733 intptr_t ignore = 0;
1734 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1735 if (base != NULL
1736 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1737 // Check for useless control edge in some common special cases
1738 if (in(MemNode::Control) != NULL
1739 && can_remove_control()
1740 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1741 && all_controls_dominate(base, phase->C->start())) {
1742 // A method-invariant, non-null address (constant or 'this' argument).
1743 set_req(MemNode::Control, NULL);
1744 progress = true;
1745 }
1746 }
1747
1748 Node* mem = in(MemNode::Memory);
1749 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1750
1751 if (can_reshape && (addr_t != NULL)) {
1752 // try to optimize our memory input
1753 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1754 if (opt_mem != mem) {
1755 set_req_X(MemNode::Memory, opt_mem, phase);
1756 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1757 return this;
1758 }
1759 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1760 if ((t_oop != NULL) &&
1761 (t_oop->is_known_instance_field() ||
1762 t_oop->is_ptr_to_boxed_value())) {
1763 PhaseIterGVN *igvn = phase->is_IterGVN();
1764 assert(igvn != NULL, "must be PhaseIterGVN when can_reshape is true");
1765 if (igvn->_worklist.member(opt_mem)) {
1766 // Delay this transformation until memory Phi is processed.
1767 igvn->_worklist.push(this);
1768 return NULL;
1769 }
1770 // Split instance field load through Phi.
1771 Node* result = split_through_phi(phase);
1772 if (result != NULL) return result;
1773
1774 if (t_oop->is_ptr_to_boxed_value()) {
1775 Node* result = eliminate_autobox(igvn);
1776 if (result != NULL) return result;
1777 }
1778 }
1779 }
1780
1781 // Is there a dominating load that loads the same value? Leave
1782 // anything that is not a load of a field/array element (like
1783 // barriers etc.) alone
1784 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1785 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1786 Node *use = mem->fast_out(i);
1787 if (use != this &&
1788 use->Opcode() == Opcode() &&
1789 use->in(0) != NULL &&
1790 use->in(0) != in(0) &&
1791 use->in(Address) == in(Address)) {
1792 Node* ctl = in(0);
1793 for (int i = 0; i < 10 && ctl != NULL; i++) {
1794 ctl = IfNode::up_one_dom(ctl);
1795 if (ctl == use->in(0)) {
1796 set_req(0, use->in(0));
1797 return this;
1798 }
1799 }
1800 }
1801 }
1802 }
1803
1804 // Check for prior store with a different base or offset; make Load
1805 // independent. Skip through any number of them. Bail out if the stores
1806 // are in an endless dead cycle and report no progress. This is a key
1807 // transform for Reflection. However, if after skipping through the Stores
1808 // we can't then fold up against a prior store do NOT do the transform as
1809 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1810 // array memory alive twice: once for the hoisted Load and again after the
1811 // bypassed Store. This situation only works if EVERYBODY who does
1812 // anti-dependence work knows how to bypass. I.e. we need all
1813 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1814 // the alias index stuff. So instead, peek through Stores and IFF we can
1815 // fold up, do so.
1816 Node* prev_mem = find_previous_store(phase);
1817 if (prev_mem != NULL) {
1818 Node* value = can_see_arraycopy_value(prev_mem, phase);
1819 if (value != NULL) {
1820 return value;
1821 }
1822 }
1823 // Steps (a), (b): Walk past independent stores to find an exact match.
1824 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1825 // (c) See if we can fold up on the spot, but don't fold up here.
1826 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1827 // just return a prior value, which is done by Identity calls.
1828 if (can_see_stored_value(prev_mem, phase)) {
1829 // Make ready for step (d):
1830 set_req_X(MemNode::Memory, prev_mem, phase);
1831 return this;
1832 }
1833 }
1834
1835 AllocateNode* alloc = is_new_object_mark_load(phase);
1836 if (alloc != NULL && alloc->Opcode() == Op_Allocate && UseBiasedLocking) {
1837 InitializeNode* init = alloc->initialization();
1838 Node* control = init->proj_out(0);
1839 return alloc->make_ideal_mark(phase, address, control, mem);
1840 }
1841
1842 return progress ? this : NULL;
1843 }
1844
1845 // Helper to recognize certain Klass fields which are invariant across
1846 // some group of array types (e.g., int[] or all T[] where T < Object).
1847 const Type*
1848 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1849 ciKlass* klass) const {
1850 if (UseCompactObjectHeaders) {
1851 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
1852 // The field is Klass::_prototype_header. Return its (constant) value.
1853 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
1854 return TypeX::make(klass->prototype_header());
1855 }
1856 }
1857 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1858 // The field is Klass::_modifier_flags. Return its (constant) value.
1859 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1860 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1861 return TypeInt::make(klass->modifier_flags());
1862 }
1863 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1864 // The field is Klass::_access_flags. Return its (constant) value.
1865 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1866 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1867 return TypeInt::make(klass->access_flags());
1868 }
1869 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1870 // The field is Klass::_layout_helper. Return its constant value if known.
1871 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1872 return TypeInt::make(klass->layout_helper());
1873 }
1874
1875 // No match.
1876 return NULL;
1877 }
1878
1879 //------------------------------Value-----------------------------------------
1880 const Type* LoadNode::Value(PhaseGVN* phase) const {
1881 // Either input is TOP ==> the result is TOP
1882 Node* mem = in(MemNode::Memory);
1883 const Type *t1 = phase->type(mem);
1884 if (t1 == Type::TOP) return Type::TOP;
1885 Node* adr = in(MemNode::Address);
1886 const TypePtr* tp = phase->type(adr)->isa_ptr();
1887 if (tp == NULL || tp->empty()) return Type::TOP;
1888 int off = tp->offset();
1889 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1890 Compile* C = phase->C;
1891
1892 // Try to guess loaded type from pointer type
1893 if (tp->isa_aryptr()) {
1894 const TypeAryPtr* ary = tp->is_aryptr();
1895 const Type* t = ary->elem();
1896
1897 // Determine whether the reference is beyond the header or not, by comparing
1898 // the offset against the offset of the start of the array's data.
1899 // Different array types begin at slightly different offsets (12 vs. 16).
1900 // We choose T_BYTE as an example base type that is least restrictive
1901 // as to alignment, which will therefore produce the smallest
1902 // possible base offset.
1903 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1904 const bool off_beyond_header = (off >= min_base_off);
1905
1906 // Try to constant-fold a stable array element.
1907 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1908 // Make sure the reference is not into the header and the offset is constant
1909 ciObject* aobj = ary->const_oop();
1910 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1911 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1912 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1913 stable_dimension,
1914 memory_type(), is_unsigned());
1915 if (con_type != NULL) {
1916 return con_type;
1917 }
1918 }
1919 }
1920
1921 // Don't do this for integer types. There is only potential profit if
1922 // the element type t is lower than _type; that is, for int types, if _type is
1923 // more restrictive than t. This only happens here if one is short and the other
1924 // char (both 16 bits), and in those cases we've made an intentional decision
1925 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1926 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1927 //
1928 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1929 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1930 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1931 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1932 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1933 // In fact, that could have been the original type of p1, and p1 could have
1934 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1935 // expression (LShiftL quux 3) independently optimized to the constant 8.
1936 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1937 && (_type->isa_vect() == NULL)
1938 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1939 // t might actually be lower than _type, if _type is a unique
1940 // concrete subclass of abstract class t.
1941 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1942 const Type* jt = t->join_speculative(_type);
1943 // In any case, do not allow the join, per se, to empty out the type.
1944 if (jt->empty() && !t->empty()) {
1945 // This can happen if a interface-typed array narrows to a class type.
1946 jt = _type;
1947 }
1948 #ifdef ASSERT
1949 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1950 // The pointers in the autobox arrays are always non-null
1951 Node* base = adr->in(AddPNode::Base);
1952 if ((base != NULL) && base->is_DecodeN()) {
1953 // Get LoadN node which loads IntegerCache.cache field
1954 base = base->in(1);
1955 }
1956 if ((base != NULL) && base->is_Con()) {
1957 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1958 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1959 // It could be narrow oop
1960 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1961 }
1962 }
1963 }
1964 #endif
1965 return jt;
1966 }
1967 }
1968 } else if (tp->base() == Type::InstPtr) {
1969 assert( off != Type::OffsetBot ||
1970 // arrays can be cast to Objects
1971 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1972 // unsafe field access may not have a constant offset
1973 C->has_unsafe_access(),
1974 "Field accesses must be precise" );
1975 // For oop loads, we expect the _type to be precise.
1976
1977 // Optimize loads from constant fields.
1978 const TypeInstPtr* tinst = tp->is_instptr();
1979 ciObject* const_oop = tinst->const_oop();
1980 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
1981 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), memory_type());
1982 if (con_type != NULL) {
1983 return con_type;
1984 }
1985 }
1986 } else if (tp->base() == Type::KlassPtr) {
1987 assert( off != Type::OffsetBot ||
1988 // arrays can be cast to Objects
1989 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1990 // also allow array-loading from the primary supertype
1991 // array during subtype checks
1992 Opcode() == Op_LoadKlass,
1993 "Field accesses must be precise" );
1994 // For klass/static loads, we expect the _type to be precise
1995 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
1996 /* With mirrors being an indirect in the Klass*
1997 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
1998 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
1999 *
2000 * So check the type and klass of the node before the LoadP.
2001 */
2002 Node* adr2 = adr->in(MemNode::Address);
2003 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2004 if (tkls != NULL && !StressReflectiveCode) {
2005 ciKlass* klass = tkls->klass();
2006 if (klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2007 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2008 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2009 return TypeInstPtr::make(klass->java_mirror());
2010 }
2011 }
2012 }
2013
2014 const TypeKlassPtr *tkls = tp->isa_klassptr();
2015 if (tkls != NULL && !StressReflectiveCode) {
2016 ciKlass* klass = tkls->klass();
2017 if (klass->is_loaded() && tkls->klass_is_exact()) {
2018 // We are loading a field from a Klass metaobject whose identity
2019 // is known at compile time (the type is "exact" or "precise").
2020 // Check for fields we know are maintained as constants by the VM.
2021 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2022 // The field is Klass::_super_check_offset. Return its (constant) value.
2023 // (Folds up type checking code.)
2024 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2025 return TypeInt::make(klass->super_check_offset());
2026 }
2027 if (UseCompactObjectHeaders) {
2028 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2029 // The field is Klass::_prototype_header. Return its (constant) value.
2030 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2031 return TypeX::make(klass->prototype_header());
2032 }
2033 }
2034 // Compute index into primary_supers array
2035 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2036 // Check for overflowing; use unsigned compare to handle the negative case.
2037 if( depth < ciKlass::primary_super_limit() ) {
2038 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2039 // (Folds up type checking code.)
2040 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2041 ciKlass *ss = klass->super_of_depth(depth);
2042 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2043 }
2044 const Type* aift = load_array_final_field(tkls, klass);
2045 if (aift != NULL) return aift;
2046 }
2047
2048 // We can still check if we are loading from the primary_supers array at a
2049 // shallow enough depth. Even though the klass is not exact, entries less
2050 // than or equal to its super depth are correct.
2051 if (klass->is_loaded() ) {
2052 ciType *inner = klass;
2053 while( inner->is_obj_array_klass() )
2054 inner = inner->as_obj_array_klass()->base_element_type();
2055 if( inner->is_instance_klass() &&
2056 !inner->as_instance_klass()->flags().is_interface() ) {
2057 // Compute index into primary_supers array
2058 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2059 // Check for overflowing; use unsigned compare to handle the negative case.
2060 if( depth < ciKlass::primary_super_limit() &&
2061 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
2062 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2063 // (Folds up type checking code.)
2064 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2065 ciKlass *ss = klass->super_of_depth(depth);
2066 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2067 }
2068 }
2069 }
2070
2071 // If the type is enough to determine that the thing is not an array,
2072 // we can give the layout_helper a positive interval type.
2073 // This will help short-circuit some reflective code.
2074 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
2075 && !klass->is_array_klass() // not directly typed as an array
2076 && !klass->is_interface() // specifically not Serializable & Cloneable
2077 && !klass->is_java_lang_Object() // not the supertype of all T[]
2078 ) {
2079 // Note: When interfaces are reliable, we can narrow the interface
2080 // test to (klass != Serializable && klass != Cloneable).
2081 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2082 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2083 // The key property of this type is that it folds up tests
2084 // for array-ness, since it proves that the layout_helper is positive.
2085 // Thus, a generic value like the basic object layout helper works fine.
2086 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2087 }
2088 }
2089
2090 // If we are loading from a freshly-allocated object, produce a zero,
2091 // if the load is provably beyond the header of the object.
2092 // (Also allow a variable load from a fresh array to produce zero.)
2093 const TypeOopPtr *tinst = tp->isa_oopptr();
2094 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
2095 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
2096 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2097 Node* value = can_see_stored_value(mem,phase);
2098 if (value != NULL && value->is_Con()) {
2099 assert(value->bottom_type()->higher_equal(_type),"sanity");
2100 return value->bottom_type();
2101 }
2102 }
2103
2104 bool is_vect = (_type->isa_vect() != NULL);
2105 if (is_instance && !is_vect) {
2106 // If we have an instance type and our memory input is the
2107 // programs's initial memory state, there is no matching store,
2108 // so just return a zero of the appropriate type -
2109 // except if it is vectorized - then we have no zero constant.
2110 Node *mem = in(MemNode::Memory);
2111 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2112 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2113 return Type::get_zero_type(_type->basic_type());
2114 }
2115 }
2116
2117 Node* alloc = is_new_object_mark_load(phase);
2118 if (alloc != NULL && !(alloc->Opcode() == Op_Allocate && UseBiasedLocking) && !UseCompactObjectHeaders) {
2119 return TypeX::make(markWord::prototype().value());
2120 }
2121
2122 return _type;
2123 }
2124
2125 //------------------------------match_edge-------------------------------------
2126 // Do we Match on this edge index or not? Match only the address.
2127 uint LoadNode::match_edge(uint idx) const {
2128 return idx == MemNode::Address;
2129 }
2130
2131 //--------------------------LoadBNode::Ideal--------------------------------------
2132 //
2133 // If the previous store is to the same address as this load,
2134 // and the value stored was larger than a byte, replace this load
2135 // with the value stored truncated to a byte. If no truncation is
2136 // needed, the replacement is done in LoadNode::Identity().
2137 //
2138 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2139 Node* mem = in(MemNode::Memory);
2140 Node* value = can_see_stored_value(mem,phase);
2141 if (value != NULL) {
2142 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2143 if (narrow != value) {
2144 return narrow;
2145 }
2146 }
2147 // Identity call will handle the case where truncation is not needed.
2148 return LoadNode::Ideal(phase, can_reshape);
2149 }
2150
2151 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2152 Node* mem = in(MemNode::Memory);
2153 Node* value = can_see_stored_value(mem,phase);
2154 if (value != NULL && value->is_Con() &&
2155 !value->bottom_type()->higher_equal(_type)) {
2156 // If the input to the store does not fit with the load's result type,
2157 // it must be truncated. We can't delay until Ideal call since
2158 // a singleton Value is needed for split_thru_phi optimization.
2159 int con = value->get_int();
2160 return TypeInt::make((con << 24) >> 24);
2161 }
2162 return LoadNode::Value(phase);
2163 }
2164
2165 //--------------------------LoadUBNode::Ideal-------------------------------------
2166 //
2167 // If the previous store is to the same address as this load,
2168 // and the value stored was larger than a byte, replace this load
2169 // with the value stored truncated to a byte. If no truncation is
2170 // needed, the replacement is done in LoadNode::Identity().
2171 //
2172 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2173 Node* mem = in(MemNode::Memory);
2174 Node* value = can_see_stored_value(mem, phase);
2175 if (value != NULL) {
2176 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2177 if (narrow != value) {
2178 return narrow;
2179 }
2180 }
2181 // Identity call will handle the case where truncation is not needed.
2182 return LoadNode::Ideal(phase, can_reshape);
2183 }
2184
2185 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2186 Node* mem = in(MemNode::Memory);
2187 Node* value = can_see_stored_value(mem,phase);
2188 if (value != NULL && value->is_Con() &&
2189 !value->bottom_type()->higher_equal(_type)) {
2190 // If the input to the store does not fit with the load's result type,
2191 // it must be truncated. We can't delay until Ideal call since
2192 // a singleton Value is needed for split_thru_phi optimization.
2193 int con = value->get_int();
2194 return TypeInt::make(con & 0xFF);
2195 }
2196 return LoadNode::Value(phase);
2197 }
2198
2199 //--------------------------LoadUSNode::Ideal-------------------------------------
2200 //
2201 // If the previous store is to the same address as this load,
2202 // and the value stored was larger than a char, replace this load
2203 // with the value stored truncated to a char. If no truncation is
2204 // needed, the replacement is done in LoadNode::Identity().
2205 //
2206 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2207 Node* mem = in(MemNode::Memory);
2208 Node* value = can_see_stored_value(mem,phase);
2209 if (value != NULL) {
2210 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2211 if (narrow != value) {
2212 return narrow;
2213 }
2214 }
2215 // Identity call will handle the case where truncation is not needed.
2216 return LoadNode::Ideal(phase, can_reshape);
2217 }
2218
2219 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2220 Node* mem = in(MemNode::Memory);
2221 Node* value = can_see_stored_value(mem,phase);
2222 if (value != NULL && value->is_Con() &&
2223 !value->bottom_type()->higher_equal(_type)) {
2224 // If the input to the store does not fit with the load's result type,
2225 // it must be truncated. We can't delay until Ideal call since
2226 // a singleton Value is needed for split_thru_phi optimization.
2227 int con = value->get_int();
2228 return TypeInt::make(con & 0xFFFF);
2229 }
2230 return LoadNode::Value(phase);
2231 }
2232
2233 //--------------------------LoadSNode::Ideal--------------------------------------
2234 //
2235 // If the previous store is to the same address as this load,
2236 // and the value stored was larger than a short, replace this load
2237 // with the value stored truncated to a short. If no truncation is
2238 // needed, the replacement is done in LoadNode::Identity().
2239 //
2240 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2241 Node* mem = in(MemNode::Memory);
2242 Node* value = can_see_stored_value(mem,phase);
2243 if (value != NULL) {
2244 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2245 if (narrow != value) {
2246 return narrow;
2247 }
2248 }
2249 // Identity call will handle the case where truncation is not needed.
2250 return LoadNode::Ideal(phase, can_reshape);
2251 }
2252
2253 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2254 Node* mem = in(MemNode::Memory);
2255 Node* value = can_see_stored_value(mem,phase);
2256 if (value != NULL && value->is_Con() &&
2257 !value->bottom_type()->higher_equal(_type)) {
2258 // If the input to the store does not fit with the load's result type,
2259 // it must be truncated. We can't delay until Ideal call since
2260 // a singleton Value is needed for split_thru_phi optimization.
2261 int con = value->get_int();
2262 return TypeInt::make((con << 16) >> 16);
2263 }
2264 return LoadNode::Value(phase);
2265 }
2266
2267 //=============================================================================
2268 //----------------------------LoadKlassNode::make------------------------------
2269 // Polymorphic factory method:
2270 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2271 // sanity check the alias category against the created node type
2272 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2273 assert(adr_type != NULL, "expecting TypeKlassPtr");
2274 #ifdef _LP64
2275 if (adr_type->is_ptr_to_narrowklass()) {
2276 assert(UseCompressedClassPointers, "no compressed klasses");
2277 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2278 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2279 }
2280 #endif
2281 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2282 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2283 }
2284
2285 //------------------------------Value------------------------------------------
2286 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2287 return klass_value_common(phase);
2288 }
2289
2290 // In most cases, LoadKlassNode does not have the control input set. If the control
2291 // input is set, it must not be removed (by LoadNode::Ideal()).
2292 bool LoadKlassNode::can_remove_control() const {
2293 return false;
2294 }
2295
2296 const Type* LoadNode::klass_value_common(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()) ||
2305 tp->ptr() == TypePtr::Null) return Type::TOP;
2306
2307 // Return a more precise klass, if possible
2308 const TypeInstPtr *tinst = tp->isa_instptr();
2309 if (tinst != NULL) {
2310 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2311 int offset = tinst->offset();
2312 if (ik == phase->C->env()->Class_klass()
2313 && (offset == java_lang_Class::klass_offset() ||
2314 offset == java_lang_Class::array_klass_offset())) {
2315 // We are loading a special hidden field from a Class mirror object,
2316 // the field which points to the VM's Klass metaobject.
2317 ciType* t = tinst->java_mirror_type();
2318 // java_mirror_type returns non-null for compile-time Class constants.
2319 if (t != NULL) {
2320 // constant oop => constant klass
2321 if (offset == java_lang_Class::array_klass_offset()) {
2322 if (t->is_void()) {
2323 // We cannot create a void array. Since void is a primitive type return null
2324 // klass. Users of this result need to do a null check on the returned klass.
2325 return TypePtr::NULL_PTR;
2326 }
2327 return TypeKlassPtr::make(ciArrayKlass::make(t));
2328 }
2329 if (!t->is_klass()) {
2330 // a primitive Class (e.g., int.class) has NULL for a klass field
2331 return TypePtr::NULL_PTR;
2332 }
2333 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2334 return TypeKlassPtr::make(t->as_klass());
2335 }
2336 // non-constant mirror, so we can't tell what's going on
2337 }
2338 if( !ik->is_loaded() )
2339 return _type; // Bail out if not loaded
2340 if (offset == oopDesc::klass_offset_in_bytes()) {
2341 if (tinst->klass_is_exact()) {
2342 return TypeKlassPtr::make(ik);
2343 }
2344 // See if we can become precise: no subklasses and no interface
2345 // (Note: We need to support verified interfaces.)
2346 if (!ik->is_interface() && !ik->has_subklass()) {
2347 // Add a dependence; if any subclass added we need to recompile
2348 if (!ik->is_final()) {
2349 // %%% should use stronger assert_unique_concrete_subtype instead
2350 phase->C->dependencies()->assert_leaf_type(ik);
2351 }
2352 // Return precise klass
2353 return TypeKlassPtr::make(ik);
2354 }
2355
2356 // Return root of possible klass
2357 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2358 }
2359 }
2360
2361 // Check for loading klass from an array
2362 const TypeAryPtr *tary = tp->isa_aryptr();
2363 if( tary != NULL ) {
2364 ciKlass *tary_klass = tary->klass();
2365 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2366 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2367 if (tary->klass_is_exact()) {
2368 return TypeKlassPtr::make(tary_klass);
2369 }
2370 ciArrayKlass *ak = tary->klass()->as_array_klass();
2371 // If the klass is an object array, we defer the question to the
2372 // array component klass.
2373 if( ak->is_obj_array_klass() ) {
2374 assert( ak->is_loaded(), "" );
2375 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2376 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2377 ciInstanceKlass* ik = base_k->as_instance_klass();
2378 // See if we can become precise: no subklasses and no interface
2379 if (!ik->is_interface() && !ik->has_subklass()) {
2380 // Add a dependence; if any subclass added we need to recompile
2381 if (!ik->is_final()) {
2382 phase->C->dependencies()->assert_leaf_type(ik);
2383 }
2384 // Return precise array klass
2385 return TypeKlassPtr::make(ak);
2386 }
2387 }
2388 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2389 } else { // Found a type-array?
2390 assert( ak->is_type_array_klass(), "" );
2391 return TypeKlassPtr::make(ak); // These are always precise
2392 }
2393 }
2394 }
2395
2396 // Check for loading klass from an array klass
2397 const TypeKlassPtr *tkls = tp->isa_klassptr();
2398 if (tkls != NULL && !StressReflectiveCode) {
2399 ciKlass* klass = tkls->klass();
2400 if( !klass->is_loaded() )
2401 return _type; // Bail out if not loaded
2402 if( klass->is_obj_array_klass() &&
2403 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2404 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2405 // // Always returning precise element type is incorrect,
2406 // // e.g., element type could be object and array may contain strings
2407 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2408
2409 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2410 // according to the element type's subclassing.
2411 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2412 }
2413 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2414 tkls->offset() == in_bytes(Klass::super_offset())) {
2415 ciKlass* sup = klass->as_instance_klass()->super();
2416 // The field is Klass::_super. Return its (constant) value.
2417 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2418 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2419 }
2420 }
2421
2422 // Bailout case
2423 return LoadNode::Value(phase);
2424 }
2425
2426 //------------------------------Identity---------------------------------------
2427 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2428 // Also feed through the klass in Allocate(...klass...)._klass.
2429 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2430 return klass_identity_common(phase);
2431 }
2432
2433 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2434 Node* x = LoadNode::Identity(phase);
2435 if (x != this) return x;
2436
2437 // Take apart the address into an oop and and offset.
2438 // Return 'this' if we cannot.
2439 Node* adr = in(MemNode::Address);
2440 intptr_t offset = 0;
2441 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2442 if (base == NULL) return this;
2443 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2444 if (toop == NULL) return this;
2445
2446 // Step over potential GC barrier for OopHandle resolve
2447 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2448 if (bs->is_gc_barrier_node(base)) {
2449 base = bs->step_over_gc_barrier(base);
2450 }
2451
2452 // We can fetch the klass directly through an AllocateNode.
2453 // This works even if the klass is not constant (clone or newArray).
2454 if (offset == oopDesc::klass_offset_in_bytes()) {
2455 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2456 if (allocated_klass != NULL) {
2457 return allocated_klass;
2458 }
2459 }
2460
2461 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2462 // See inline_native_Class_query for occurrences of these patterns.
2463 // Java Example: x.getClass().isAssignableFrom(y)
2464 //
2465 // This improves reflective code, often making the Class
2466 // mirror go completely dead. (Current exception: Class
2467 // mirrors may appear in debug info, but we could clean them out by
2468 // introducing a new debug info operator for Klass.java_mirror).
2469
2470 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2471 && offset == java_lang_Class::klass_offset()) {
2472 if (base->is_Load()) {
2473 Node* base2 = base->in(MemNode::Address);
2474 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2475 Node* adr2 = base2->in(MemNode::Address);
2476 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2477 if (tkls != NULL && !tkls->empty()
2478 && (tkls->klass()->is_instance_klass() ||
2479 tkls->klass()->is_array_klass())
2480 && adr2->is_AddP()
2481 ) {
2482 int mirror_field = in_bytes(Klass::java_mirror_offset());
2483 if (tkls->offset() == mirror_field) {
2484 return adr2->in(AddPNode::Base);
2485 }
2486 }
2487 }
2488 }
2489 }
2490
2491 return this;
2492 }
2493
2494
2495 //------------------------------Value------------------------------------------
2496 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2497 const Type *t = klass_value_common(phase);
2498 if (t == Type::TOP)
2499 return t;
2500
2501 return t->make_narrowklass();
2502 }
2503
2504 //------------------------------Identity---------------------------------------
2505 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2506 // Also feed through the klass in Allocate(...klass...)._klass.
2507 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2508 Node *x = klass_identity_common(phase);
2509
2510 const Type *t = phase->type( x );
2511 if( t == Type::TOP ) return x;
2512 if( t->isa_narrowklass()) return x;
2513 assert (!t->isa_narrowoop(), "no narrow oop here");
2514
2515 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2516 }
2517
2518 //------------------------------Value-----------------------------------------
2519 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2520 // Either input is TOP ==> the result is TOP
2521 const Type *t1 = phase->type( in(MemNode::Memory) );
2522 if( t1 == Type::TOP ) return Type::TOP;
2523 Node *adr = in(MemNode::Address);
2524 const Type *t2 = phase->type( adr );
2525 if( t2 == Type::TOP ) return Type::TOP;
2526 const TypePtr *tp = t2->is_ptr();
2527 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2528 const TypeAryPtr *tap = tp->isa_aryptr();
2529 if( !tap ) return _type;
2530 return tap->size();
2531 }
2532
2533 //-------------------------------Ideal---------------------------------------
2534 // Feed through the length in AllocateArray(...length...)._length.
2535 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2536 Node* p = MemNode::Ideal_common(phase, can_reshape);
2537 if (p) return (p == NodeSentinel) ? NULL : p;
2538
2539 // Take apart the address into an oop and and offset.
2540 // Return 'this' if we cannot.
2541 Node* adr = in(MemNode::Address);
2542 intptr_t offset = 0;
2543 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2544 if (base == NULL) return NULL;
2545 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2546 if (tary == NULL) return NULL;
2547
2548 // We can fetch the length directly through an AllocateArrayNode.
2549 // This works even if the length is not constant (clone or newArray).
2550 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2551 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2552 if (alloc != NULL) {
2553 Node* allocated_length = alloc->Ideal_length();
2554 Node* len = alloc->make_ideal_length(tary, phase);
2555 if (allocated_length != len) {
2556 // New CastII improves on this.
2557 return len;
2558 }
2559 }
2560 }
2561
2562 return NULL;
2563 }
2564
2565 //------------------------------Identity---------------------------------------
2566 // Feed through the length in AllocateArray(...length...)._length.
2567 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2568 Node* x = LoadINode::Identity(phase);
2569 if (x != this) return x;
2570
2571 // Take apart the address into an oop and and offset.
2572 // Return 'this' if we cannot.
2573 Node* adr = in(MemNode::Address);
2574 intptr_t offset = 0;
2575 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2576 if (base == NULL) return this;
2577 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2578 if (tary == NULL) return this;
2579
2580 // We can fetch the length directly through an AllocateArrayNode.
2581 // This works even if the length is not constant (clone or newArray).
2582 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2583 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2584 if (alloc != NULL) {
2585 Node* allocated_length = alloc->Ideal_length();
2586 // Do not allow make_ideal_length to allocate a CastII node.
2587 Node* len = alloc->make_ideal_length(tary, phase, false);
2588 if (allocated_length == len) {
2589 // Return allocated_length only if it would not be improved by a CastII.
2590 return allocated_length;
2591 }
2592 }
2593 }
2594
2595 return this;
2596
2597 }
2598
2599 //=============================================================================
2600 //---------------------------StoreNode::make-----------------------------------
2601 // Polymorphic factory method:
2602 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo, bool require_atomic_access) {
2603 assert((mo == unordered || mo == release), "unexpected");
2604 Compile* C = gvn.C;
2605 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2606 ctl != NULL, "raw memory operations should have control edge");
2607
2608 switch (bt) {
2609 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2610 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2611 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2612 case T_CHAR:
2613 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2614 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2615 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2616 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2617 case T_METADATA:
2618 case T_ADDRESS:
2619 case T_OBJECT:
2620 #ifdef _LP64
2621 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2622 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2623 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2624 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2625 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2626 adr->bottom_type()->isa_rawptr())) {
2627 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2628 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2629 }
2630 #endif
2631 {
2632 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2633 }
2634 default:
2635 ShouldNotReachHere();
2636 return (StoreNode*)NULL;
2637 }
2638 }
2639
2640 //--------------------------bottom_type----------------------------------------
2641 const Type *StoreNode::bottom_type() const {
2642 return Type::MEMORY;
2643 }
2644
2645 //------------------------------hash-------------------------------------------
2646 uint StoreNode::hash() const {
2647 // unroll addition of interesting fields
2648 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2649
2650 // Since they are not commoned, do not hash them:
2651 return NO_HASH;
2652 }
2653
2654 //------------------------------Ideal------------------------------------------
2655 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2656 // When a store immediately follows a relevant allocation/initialization,
2657 // try to capture it into the initialization, or hoist it above.
2658 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2659 Node* p = MemNode::Ideal_common(phase, can_reshape);
2660 if (p) return (p == NodeSentinel) ? NULL : p;
2661
2662 Node* mem = in(MemNode::Memory);
2663 Node* address = in(MemNode::Address);
2664 Node* value = in(MemNode::ValueIn);
2665 // Back-to-back stores to same address? Fold em up. Generally
2666 // unsafe if I have intervening uses... Also disallowed for StoreCM
2667 // since they must follow each StoreP operation. Redundant StoreCMs
2668 // are eliminated just before matching in final_graph_reshape.
2669 {
2670 Node* st = mem;
2671 // If Store 'st' has more than one use, we cannot fold 'st' away.
2672 // For example, 'st' might be the final state at a conditional
2673 // return. Or, 'st' might be used by some node which is live at
2674 // the same time 'st' is live, which might be unschedulable. So,
2675 // require exactly ONE user until such time as we clone 'mem' for
2676 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2677 // true).
2678 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2679 // Looking at a dead closed cycle of memory?
2680 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2681 assert(Opcode() == st->Opcode() ||
2682 st->Opcode() == Op_StoreVector ||
2683 Opcode() == Op_StoreVector ||
2684 st->Opcode() == Op_StoreVectorScatter ||
2685 Opcode() == Op_StoreVectorScatter ||
2686 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2687 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2688 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2689 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2690 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2691
2692 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2693 st->as_Store()->memory_size() <= this->memory_size()) {
2694 Node* use = st->raw_out(0);
2695 if (phase->is_IterGVN()) {
2696 phase->is_IterGVN()->rehash_node_delayed(use);
2697 }
2698 // It's OK to do this in the parser, since DU info is always accurate,
2699 // and the parser always refers to nodes via SafePointNode maps.
2700 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2701 return this;
2702 }
2703 st = st->in(MemNode::Memory);
2704 }
2705 }
2706
2707
2708 // Capture an unaliased, unconditional, simple store into an initializer.
2709 // Or, if it is independent of the allocation, hoist it above the allocation.
2710 if (ReduceFieldZeroing && /*can_reshape &&*/
2711 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2712 InitializeNode* init = mem->in(0)->as_Initialize();
2713 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2714 if (offset > 0) {
2715 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2716 // If the InitializeNode captured me, it made a raw copy of me,
2717 // and I need to disappear.
2718 if (moved != NULL) {
2719 // %%% hack to ensure that Ideal returns a new node:
2720 mem = MergeMemNode::make(mem);
2721 return mem; // fold me away
2722 }
2723 }
2724 }
2725
2726 // Fold reinterpret cast into memory operation:
2727 // StoreX mem (MoveY2X v) => StoreY mem v
2728 if (value->is_Move()) {
2729 const Type* vt = value->in(1)->bottom_type();
2730 if (has_reinterpret_variant(vt)) {
2731 if (phase->C->post_loop_opts_phase()) {
2732 return convert_to_reinterpret_store(*phase, value->in(1), vt);
2733 } else {
2734 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2735 }
2736 }
2737 }
2738
2739 return NULL; // No further progress
2740 }
2741
2742 //------------------------------Value-----------------------------------------
2743 const Type* StoreNode::Value(PhaseGVN* phase) const {
2744 // Either input is TOP ==> the result is TOP
2745 const Type *t1 = phase->type( in(MemNode::Memory) );
2746 if( t1 == Type::TOP ) return Type::TOP;
2747 const Type *t2 = phase->type( in(MemNode::Address) );
2748 if( t2 == Type::TOP ) return Type::TOP;
2749 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2750 if( t3 == Type::TOP ) return Type::TOP;
2751 return Type::MEMORY;
2752 }
2753
2754 //------------------------------Identity---------------------------------------
2755 // Remove redundant stores:
2756 // Store(m, p, Load(m, p)) changes to m.
2757 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2758 Node* StoreNode::Identity(PhaseGVN* phase) {
2759 Node* mem = in(MemNode::Memory);
2760 Node* adr = in(MemNode::Address);
2761 Node* val = in(MemNode::ValueIn);
2762
2763 Node* result = this;
2764
2765 // Load then Store? Then the Store is useless
2766 if (val->is_Load() &&
2767 val->in(MemNode::Address)->eqv_uncast(adr) &&
2768 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2769 val->as_Load()->store_Opcode() == Opcode()) {
2770 result = mem;
2771 }
2772
2773 // Two stores in a row of the same value?
2774 if (result == this &&
2775 mem->is_Store() &&
2776 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2777 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2778 mem->Opcode() == Opcode()) {
2779 result = mem;
2780 }
2781
2782 // Store of zero anywhere into a freshly-allocated object?
2783 // Then the store is useless.
2784 // (It must already have been captured by the InitializeNode.)
2785 if (result == this &&
2786 ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2787 // a newly allocated object is already all-zeroes everywhere
2788 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2789 result = mem;
2790 }
2791
2792 if (result == this) {
2793 // the store may also apply to zero-bits in an earlier object
2794 Node* prev_mem = find_previous_store(phase);
2795 // Steps (a), (b): Walk past independent stores to find an exact match.
2796 if (prev_mem != NULL) {
2797 Node* prev_val = can_see_stored_value(prev_mem, phase);
2798 if (prev_val != NULL && prev_val == val) {
2799 // prev_val and val might differ by a cast; it would be good
2800 // to keep the more informative of the two.
2801 result = mem;
2802 }
2803 }
2804 }
2805 }
2806
2807 PhaseIterGVN* igvn = phase->is_IterGVN();
2808 if (result != this && igvn != NULL) {
2809 MemBarNode* trailing = trailing_membar();
2810 if (trailing != NULL) {
2811 #ifdef ASSERT
2812 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2813 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2814 #endif
2815 trailing->remove(igvn);
2816 }
2817 }
2818
2819 return result;
2820 }
2821
2822 //------------------------------match_edge-------------------------------------
2823 // Do we Match on this edge index or not? Match only memory & value
2824 uint StoreNode::match_edge(uint idx) const {
2825 return idx == MemNode::Address || idx == MemNode::ValueIn;
2826 }
2827
2828 //------------------------------cmp--------------------------------------------
2829 // Do not common stores up together. They generally have to be split
2830 // back up anyways, so do not bother.
2831 bool StoreNode::cmp( const Node &n ) const {
2832 return (&n == this); // Always fail except on self
2833 }
2834
2835 //------------------------------Ideal_masked_input-----------------------------
2836 // Check for a useless mask before a partial-word store
2837 // (StoreB ... (AndI valIn conIa) )
2838 // If (conIa & mask == mask) this simplifies to
2839 // (StoreB ... (valIn) )
2840 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2841 Node *val = in(MemNode::ValueIn);
2842 if( val->Opcode() == Op_AndI ) {
2843 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2844 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2845 set_req_X(MemNode::ValueIn, val->in(1), phase);
2846 return this;
2847 }
2848 }
2849 return NULL;
2850 }
2851
2852
2853 //------------------------------Ideal_sign_extended_input----------------------
2854 // Check for useless sign-extension before a partial-word store
2855 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2856 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2857 // (StoreB ... (valIn) )
2858 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2859 Node *val = in(MemNode::ValueIn);
2860 if( val->Opcode() == Op_RShiftI ) {
2861 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2862 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2863 Node *shl = val->in(1);
2864 if( shl->Opcode() == Op_LShiftI ) {
2865 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2866 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2867 set_req_X(MemNode::ValueIn, shl->in(1), phase);
2868 return this;
2869 }
2870 }
2871 }
2872 }
2873 return NULL;
2874 }
2875
2876 //------------------------------value_never_loaded-----------------------------------
2877 // Determine whether there are any possible loads of the value stored.
2878 // For simplicity, we actually check if there are any loads from the
2879 // address stored to, not just for loads of the value stored by this node.
2880 //
2881 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2882 Node *adr = in(Address);
2883 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2884 if (adr_oop == NULL)
2885 return false;
2886 if (!adr_oop->is_known_instance_field())
2887 return false; // if not a distinct instance, there may be aliases of the address
2888 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2889 Node *use = adr->fast_out(i);
2890 if (use->is_Load() || use->is_LoadStore()) {
2891 return false;
2892 }
2893 }
2894 return true;
2895 }
2896
2897 MemBarNode* StoreNode::trailing_membar() const {
2898 if (is_release()) {
2899 MemBarNode* trailing_mb = NULL;
2900 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2901 Node* u = fast_out(i);
2902 if (u->is_MemBar()) {
2903 if (u->as_MemBar()->trailing_store()) {
2904 assert(u->Opcode() == Op_MemBarVolatile, "");
2905 assert(trailing_mb == NULL, "only one");
2906 trailing_mb = u->as_MemBar();
2907 #ifdef ASSERT
2908 Node* leading = u->as_MemBar()->leading_membar();
2909 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2910 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2911 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2912 #endif
2913 } else {
2914 assert(u->as_MemBar()->standalone(), "");
2915 }
2916 }
2917 }
2918 return trailing_mb;
2919 }
2920 return NULL;
2921 }
2922
2923
2924 //=============================================================================
2925 //------------------------------Ideal------------------------------------------
2926 // If the store is from an AND mask that leaves the low bits untouched, then
2927 // we can skip the AND operation. If the store is from a sign-extension
2928 // (a left shift, then right shift) we can skip both.
2929 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2930 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2931 if( progress != NULL ) return progress;
2932
2933 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2934 if( progress != NULL ) return progress;
2935
2936 // Finally check the default case
2937 return StoreNode::Ideal(phase, can_reshape);
2938 }
2939
2940 //=============================================================================
2941 //------------------------------Ideal------------------------------------------
2942 // If the store is from an AND mask that leaves the low bits untouched, then
2943 // we can skip the AND operation
2944 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2945 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2946 if( progress != NULL ) return progress;
2947
2948 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2949 if( progress != NULL ) return progress;
2950
2951 // Finally check the default case
2952 return StoreNode::Ideal(phase, can_reshape);
2953 }
2954
2955 //=============================================================================
2956 //------------------------------Identity---------------------------------------
2957 Node* StoreCMNode::Identity(PhaseGVN* phase) {
2958 // No need to card mark when storing a null ptr
2959 Node* my_store = in(MemNode::OopStore);
2960 if (my_store->is_Store()) {
2961 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2962 if( t1 == TypePtr::NULL_PTR ) {
2963 return in(MemNode::Memory);
2964 }
2965 }
2966 return this;
2967 }
2968
2969 //=============================================================================
2970 //------------------------------Ideal---------------------------------------
2971 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2972 Node* progress = StoreNode::Ideal(phase, can_reshape);
2973 if (progress != NULL) return progress;
2974
2975 Node* my_store = in(MemNode::OopStore);
2976 if (my_store->is_MergeMem()) {
2977 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2978 set_req_X(MemNode::OopStore, mem, phase);
2979 return this;
2980 }
2981
2982 return NULL;
2983 }
2984
2985 //------------------------------Value-----------------------------------------
2986 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
2987 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
2988 // If extra input is TOP ==> the result is TOP
2989 const Type* t = phase->type(in(MemNode::OopStore));
2990 if (t == Type::TOP) {
2991 return Type::TOP;
2992 }
2993 return StoreNode::Value(phase);
2994 }
2995
2996
2997 //=============================================================================
2998 //----------------------------------SCMemProjNode------------------------------
2999 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3000 {
3001 if (in(0) == NULL || phase->type(in(0)) == Type::TOP) {
3002 return Type::TOP;
3003 }
3004 return bottom_type();
3005 }
3006
3007 //=============================================================================
3008 //----------------------------------LoadStoreNode------------------------------
3009 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3010 : Node(required),
3011 _type(rt),
3012 _adr_type(at),
3013 _barrier_data(0)
3014 {
3015 init_req(MemNode::Control, c );
3016 init_req(MemNode::Memory , mem);
3017 init_req(MemNode::Address, adr);
3018 init_req(MemNode::ValueIn, val);
3019 init_class_id(Class_LoadStore);
3020 }
3021
3022 //------------------------------Value-----------------------------------------
3023 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3024 // Either input is TOP ==> the result is TOP
3025 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3026 return Type::TOP;
3027 }
3028 const Type* t = phase->type(in(MemNode::Memory));
3029 if (t == Type::TOP) {
3030 return Type::TOP;
3031 }
3032 t = phase->type(in(MemNode::Address));
3033 if (t == Type::TOP) {
3034 return Type::TOP;
3035 }
3036 t = phase->type(in(MemNode::ValueIn));
3037 if (t == Type::TOP) {
3038 return Type::TOP;
3039 }
3040 return bottom_type();
3041 }
3042
3043 uint LoadStoreNode::ideal_reg() const {
3044 return _type->ideal_reg();
3045 }
3046
3047 bool LoadStoreNode::result_not_used() const {
3048 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3049 Node *x = fast_out(i);
3050 if (x->Opcode() == Op_SCMemProj) continue;
3051 return false;
3052 }
3053 return true;
3054 }
3055
3056 MemBarNode* LoadStoreNode::trailing_membar() const {
3057 MemBarNode* trailing = NULL;
3058 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3059 Node* u = fast_out(i);
3060 if (u->is_MemBar()) {
3061 if (u->as_MemBar()->trailing_load_store()) {
3062 assert(u->Opcode() == Op_MemBarAcquire, "");
3063 assert(trailing == NULL, "only one");
3064 trailing = u->as_MemBar();
3065 #ifdef ASSERT
3066 Node* leading = trailing->leading_membar();
3067 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3068 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3069 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3070 #endif
3071 } else {
3072 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3073 }
3074 }
3075 }
3076
3077 return trailing;
3078 }
3079
3080 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3081
3082 //=============================================================================
3083 //----------------------------------LoadStoreConditionalNode--------------------
3084 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
3085 init_req(ExpectedIn, ex );
3086 }
3087
3088 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3089 // Either input is TOP ==> the result is TOP
3090 const Type* t = phase->type(in(ExpectedIn));
3091 if (t == Type::TOP) {
3092 return Type::TOP;
3093 }
3094 return LoadStoreNode::Value(phase);
3095 }
3096
3097 //=============================================================================
3098 //-------------------------------adr_type--------------------------------------
3099 const TypePtr* ClearArrayNode::adr_type() const {
3100 Node *adr = in(3);
3101 if (adr == NULL) return NULL; // node is dead
3102 return MemNode::calculate_adr_type(adr->bottom_type());
3103 }
3104
3105 //------------------------------match_edge-------------------------------------
3106 // Do we Match on this edge index or not? Do not match memory
3107 uint ClearArrayNode::match_edge(uint idx) const {
3108 return idx > 1;
3109 }
3110
3111 //------------------------------Identity---------------------------------------
3112 // Clearing a zero length array does nothing
3113 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3114 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3115 }
3116
3117 //------------------------------Idealize---------------------------------------
3118 // Clearing a short array is faster with stores
3119 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3120 // Already know this is a large node, do not try to ideal it
3121 if (_is_large) return NULL;
3122
3123 const int unit = BytesPerLong;
3124 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3125 if (!t) return NULL;
3126 if (!t->is_con()) return NULL;
3127 intptr_t raw_count = t->get_con();
3128 intptr_t size = raw_count;
3129 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3130 // Clearing nothing uses the Identity call.
3131 // Negative clears are possible on dead ClearArrays
3132 // (see jck test stmt114.stmt11402.val).
3133 if (size <= 0 || size % unit != 0) return NULL;
3134 intptr_t count = size / unit;
3135 // Length too long; communicate this to matchers and assemblers.
3136 // Assemblers are responsible to produce fast hardware clears for it.
3137 if (size > InitArrayShortSize) {
3138 return new ClearArrayNode(in(0), in(1), in(2), in(3), true);
3139 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3140 return NULL;
3141 }
3142 if (!IdealizeClearArrayNode) return NULL;
3143 Node *mem = in(1);
3144 if( phase->type(mem)==Type::TOP ) return NULL;
3145 Node *adr = in(3);
3146 const Type* at = phase->type(adr);
3147 if( at==Type::TOP ) return NULL;
3148 const TypePtr* atp = at->isa_ptr();
3149 // adjust atp to be the correct array element address type
3150 if (atp == NULL) atp = TypePtr::BOTTOM;
3151 else atp = atp->add_offset(Type::OffsetBot);
3152 // Get base for derived pointer purposes
3153 if( adr->Opcode() != Op_AddP ) Unimplemented();
3154 Node *base = adr->in(1);
3155
3156 Node *zero = phase->makecon(TypeLong::ZERO);
3157 Node *off = phase->MakeConX(BytesPerLong);
3158 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3159 count--;
3160 while( count-- ) {
3161 mem = phase->transform(mem);
3162 adr = phase->transform(new AddPNode(base,adr,off));
3163 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
3164 }
3165 return mem;
3166 }
3167
3168 //----------------------------step_through----------------------------------
3169 // Return allocation input memory edge if it is different instance
3170 // or itself if it is the one we are looking for.
3171 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3172 Node* n = *np;
3173 assert(n->is_ClearArray(), "sanity");
3174 intptr_t offset;
3175 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3176 // This method is called only before Allocate nodes are expanded
3177 // during macro nodes expansion. Before that ClearArray nodes are
3178 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3179 // Allocate nodes are expanded) which follows allocations.
3180 assert(alloc != NULL, "should have allocation");
3181 if (alloc->_idx == instance_id) {
3182 // Can not bypass initialization of the instance we are looking for.
3183 return false;
3184 }
3185 // Otherwise skip it.
3186 InitializeNode* init = alloc->initialization();
3187 if (init != NULL)
3188 *np = init->in(TypeFunc::Memory);
3189 else
3190 *np = alloc->in(TypeFunc::Memory);
3191 return true;
3192 }
3193
3194 //----------------------------clear_memory-------------------------------------
3195 // Generate code to initialize object storage to zero.
3196 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3197 intptr_t start_offset,
3198 Node* end_offset,
3199 PhaseGVN* phase) {
3200 intptr_t offset = start_offset;
3201
3202 int unit = BytesPerLong;
3203 if ((offset % unit) != 0) {
3204 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3205 adr = phase->transform(adr);
3206 const TypePtr* atp = TypeRawPtr::BOTTOM;
3207 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3208 mem = phase->transform(mem);
3209 offset += BytesPerInt;
3210 }
3211 assert((offset % unit) == 0, "");
3212
3213 // Initialize the remaining stuff, if any, with a ClearArray.
3214 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
3215 }
3216
3217 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3218 Node* start_offset,
3219 Node* end_offset,
3220 PhaseGVN* phase) {
3221 if (start_offset == end_offset) {
3222 // nothing to do
3223 return mem;
3224 }
3225
3226 int unit = BytesPerLong;
3227 Node* zbase = start_offset;
3228 Node* zend = end_offset;
3229
3230 // Scale to the unit required by the CPU:
3231 if (!Matcher::init_array_count_is_in_bytes) {
3232 Node* shift = phase->intcon(exact_log2(unit));
3233 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3234 zend = phase->transform(new URShiftXNode(zend, shift) );
3235 }
3236
3237 // Bulk clear double-words
3238 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3239 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3240 mem = new ClearArrayNode(ctl, mem, zsize, adr, false);
3241 return phase->transform(mem);
3242 }
3243
3244 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3245 intptr_t start_offset,
3246 intptr_t end_offset,
3247 PhaseGVN* phase) {
3248 if (start_offset == end_offset) {
3249 // nothing to do
3250 return mem;
3251 }
3252
3253 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3254 intptr_t done_offset = end_offset;
3255 if ((done_offset % BytesPerLong) != 0) {
3256 done_offset -= BytesPerInt;
3257 }
3258 if (done_offset > start_offset) {
3259 mem = clear_memory(ctl, mem, dest,
3260 start_offset, phase->MakeConX(done_offset), phase);
3261 }
3262 if (done_offset < end_offset) { // emit the final 32-bit store
3263 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3264 adr = phase->transform(adr);
3265 const TypePtr* atp = TypeRawPtr::BOTTOM;
3266 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3267 mem = phase->transform(mem);
3268 done_offset += BytesPerInt;
3269 }
3270 assert(done_offset == end_offset, "");
3271 return mem;
3272 }
3273
3274 //=============================================================================
3275 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3276 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3277 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3278 #ifdef ASSERT
3279 , _pair_idx(0)
3280 #endif
3281 {
3282 init_class_id(Class_MemBar);
3283 Node* top = C->top();
3284 init_req(TypeFunc::I_O,top);
3285 init_req(TypeFunc::FramePtr,top);
3286 init_req(TypeFunc::ReturnAdr,top);
3287 if (precedent != NULL)
3288 init_req(TypeFunc::Parms, precedent);
3289 }
3290
3291 //------------------------------cmp--------------------------------------------
3292 uint MemBarNode::hash() const { return NO_HASH; }
3293 bool MemBarNode::cmp( const Node &n ) const {
3294 return (&n == this); // Always fail except on self
3295 }
3296
3297 //------------------------------make-------------------------------------------
3298 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3299 switch (opcode) {
3300 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3301 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3302 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3303 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3304 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3305 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
3306 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3307 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3308 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3309 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3310 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3311 case Op_Initialize: return new InitializeNode(C, atp, pn);
3312 default: ShouldNotReachHere(); return NULL;
3313 }
3314 }
3315
3316 void MemBarNode::remove(PhaseIterGVN *igvn) {
3317 if (outcnt() != 2) {
3318 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3319 assert(outcnt() == 1, "Only control then");
3320 }
3321 if (trailing_store() || trailing_load_store()) {
3322 MemBarNode* leading = leading_membar();
3323 if (leading != NULL) {
3324 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3325 leading->remove(igvn);
3326 }
3327 }
3328 if (proj_out_or_null(TypeFunc::Memory) != NULL) {
3329 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3330 }
3331 if (proj_out_or_null(TypeFunc::Control) != NULL) {
3332 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3333 }
3334 }
3335
3336 //------------------------------Ideal------------------------------------------
3337 // Return a node which is more "ideal" than the current node. Strip out
3338 // control copies
3339 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3340 if (remove_dead_region(phase, can_reshape)) return this;
3341 // Don't bother trying to transform a dead node
3342 if (in(0) && in(0)->is_top()) {
3343 return NULL;
3344 }
3345
3346 bool progress = false;
3347 // Eliminate volatile MemBars for scalar replaced objects.
3348 if (can_reshape && req() == (Precedent+1)) {
3349 bool eliminate = false;
3350 int opc = Opcode();
3351 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3352 // Volatile field loads and stores.
3353 Node* my_mem = in(MemBarNode::Precedent);
3354 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3355 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3356 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3357 // replace this Precedent (decodeN) with the Load instead.
3358 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3359 Node* load_node = my_mem->in(1);
3360 set_req(MemBarNode::Precedent, load_node);
3361 phase->is_IterGVN()->_worklist.push(my_mem);
3362 my_mem = load_node;
3363 } else {
3364 assert(my_mem->unique_out() == this, "sanity");
3365 del_req(Precedent);
3366 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3367 my_mem = NULL;
3368 }
3369 progress = true;
3370 }
3371 if (my_mem != NULL && my_mem->is_Mem()) {
3372 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3373 // Check for scalar replaced object reference.
3374 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3375 t_oop->offset() != Type::OffsetBot &&
3376 t_oop->offset() != Type::OffsetTop) {
3377 eliminate = true;
3378 }
3379 }
3380 } else if (opc == Op_MemBarRelease) {
3381 // Final field stores.
3382 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3383 if ((alloc != NULL) && alloc->is_Allocate() &&
3384 alloc->as_Allocate()->does_not_escape_thread()) {
3385 // The allocated object does not escape.
3386 eliminate = true;
3387 }
3388 }
3389 if (eliminate) {
3390 // Replace MemBar projections by its inputs.
3391 PhaseIterGVN* igvn = phase->is_IterGVN();
3392 remove(igvn);
3393 // Must return either the original node (now dead) or a new node
3394 // (Do not return a top here, since that would break the uniqueness of top.)
3395 return new ConINode(TypeInt::ZERO);
3396 }
3397 }
3398 return progress ? this : NULL;
3399 }
3400
3401 //------------------------------Value------------------------------------------
3402 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3403 if( !in(0) ) return Type::TOP;
3404 if( phase->type(in(0)) == Type::TOP )
3405 return Type::TOP;
3406 return TypeTuple::MEMBAR;
3407 }
3408
3409 //------------------------------match------------------------------------------
3410 // Construct projections for memory.
3411 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
3412 switch (proj->_con) {
3413 case TypeFunc::Control:
3414 case TypeFunc::Memory:
3415 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3416 }
3417 ShouldNotReachHere();
3418 return NULL;
3419 }
3420
3421 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3422 trailing->_kind = TrailingStore;
3423 leading->_kind = LeadingStore;
3424 #ifdef ASSERT
3425 trailing->_pair_idx = leading->_idx;
3426 leading->_pair_idx = leading->_idx;
3427 #endif
3428 }
3429
3430 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3431 trailing->_kind = TrailingLoadStore;
3432 leading->_kind = LeadingLoadStore;
3433 #ifdef ASSERT
3434 trailing->_pair_idx = leading->_idx;
3435 leading->_pair_idx = leading->_idx;
3436 #endif
3437 }
3438
3439 MemBarNode* MemBarNode::trailing_membar() const {
3440 ResourceMark rm;
3441 Node* trailing = (Node*)this;
3442 VectorSet seen;
3443 Node_Stack multis(0);
3444 do {
3445 Node* c = trailing;
3446 uint i = 0;
3447 do {
3448 trailing = NULL;
3449 for (; i < c->outcnt(); i++) {
3450 Node* next = c->raw_out(i);
3451 if (next != c && next->is_CFG()) {
3452 if (c->is_MultiBranch()) {
3453 if (multis.node() == c) {
3454 multis.set_index(i+1);
3455 } else {
3456 multis.push(c, i+1);
3457 }
3458 }
3459 trailing = next;
3460 break;
3461 }
3462 }
3463 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3464 break;
3465 }
3466 while (multis.size() > 0) {
3467 c = multis.node();
3468 i = multis.index();
3469 if (i < c->req()) {
3470 break;
3471 }
3472 multis.pop();
3473 }
3474 } while (multis.size() > 0);
3475 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3476
3477 MemBarNode* mb = trailing->as_MemBar();
3478 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3479 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3480 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3481 return mb;
3482 }
3483
3484 MemBarNode* MemBarNode::leading_membar() const {
3485 ResourceMark rm;
3486 VectorSet seen;
3487 Node_Stack regions(0);
3488 Node* leading = in(0);
3489 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3490 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3491 leading = NULL;
3492 while (regions.size() > 0 && leading == NULL) {
3493 Node* r = regions.node();
3494 uint i = regions.index();
3495 if (i < r->req()) {
3496 leading = r->in(i);
3497 regions.set_index(i+1);
3498 } else {
3499 regions.pop();
3500 }
3501 }
3502 if (leading == NULL) {
3503 assert(regions.size() == 0, "all paths should have been tried");
3504 return NULL;
3505 }
3506 }
3507 if (leading->is_Region()) {
3508 regions.push(leading, 2);
3509 leading = leading->in(1);
3510 } else {
3511 leading = leading->in(0);
3512 }
3513 }
3514 #ifdef ASSERT
3515 Unique_Node_List wq;
3516 wq.push((Node*)this);
3517 uint found = 0;
3518 for (uint i = 0; i < wq.size(); i++) {
3519 Node* n = wq.at(i);
3520 if (n->is_Region()) {
3521 for (uint j = 1; j < n->req(); j++) {
3522 Node* in = n->in(j);
3523 if (in != NULL && !in->is_top()) {
3524 wq.push(in);
3525 }
3526 }
3527 } else {
3528 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3529 assert(n == leading, "consistency check failed");
3530 found++;
3531 } else {
3532 Node* in = n->in(0);
3533 if (in != NULL && !in->is_top()) {
3534 wq.push(in);
3535 }
3536 }
3537 }
3538 }
3539 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3540 #endif
3541 if (leading == NULL) {
3542 return NULL;
3543 }
3544 MemBarNode* mb = leading->as_MemBar();
3545 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3546 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3547 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3548 return mb;
3549 }
3550
3551
3552 //===========================InitializeNode====================================
3553 // SUMMARY:
3554 // This node acts as a memory barrier on raw memory, after some raw stores.
3555 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3556 // The Initialize can 'capture' suitably constrained stores as raw inits.
3557 // It can coalesce related raw stores into larger units (called 'tiles').
3558 // It can avoid zeroing new storage for memory units which have raw inits.
3559 // At macro-expansion, it is marked 'complete', and does not optimize further.
3560 //
3561 // EXAMPLE:
3562 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3563 // ctl = incoming control; mem* = incoming memory
3564 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3565 // First allocate uninitialized memory and fill in the header:
3566 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3567 // ctl := alloc.Control; mem* := alloc.Memory*
3568 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3569 // Then initialize to zero the non-header parts of the raw memory block:
3570 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3571 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3572 // After the initialize node executes, the object is ready for service:
3573 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3574 // Suppose its body is immediately initialized as {1,2}:
3575 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3576 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3577 // mem.SLICE(#short[*]) := store2
3578 //
3579 // DETAILS:
3580 // An InitializeNode collects and isolates object initialization after
3581 // an AllocateNode and before the next possible safepoint. As a
3582 // memory barrier (MemBarNode), it keeps critical stores from drifting
3583 // down past any safepoint or any publication of the allocation.
3584 // Before this barrier, a newly-allocated object may have uninitialized bits.
3585 // After this barrier, it may be treated as a real oop, and GC is allowed.
3586 //
3587 // The semantics of the InitializeNode include an implicit zeroing of
3588 // the new object from object header to the end of the object.
3589 // (The object header and end are determined by the AllocateNode.)
3590 //
3591 // Certain stores may be added as direct inputs to the InitializeNode.
3592 // These stores must update raw memory, and they must be to addresses
3593 // derived from the raw address produced by AllocateNode, and with
3594 // a constant offset. They must be ordered by increasing offset.
3595 // The first one is at in(RawStores), the last at in(req()-1).
3596 // Unlike most memory operations, they are not linked in a chain,
3597 // but are displayed in parallel as users of the rawmem output of
3598 // the allocation.
3599 //
3600 // (See comments in InitializeNode::capture_store, which continue
3601 // the example given above.)
3602 //
3603 // When the associated Allocate is macro-expanded, the InitializeNode
3604 // may be rewritten to optimize collected stores. A ClearArrayNode
3605 // may also be created at that point to represent any required zeroing.
3606 // The InitializeNode is then marked 'complete', prohibiting further
3607 // capturing of nearby memory operations.
3608 //
3609 // During macro-expansion, all captured initializations which store
3610 // constant values of 32 bits or smaller are coalesced (if advantageous)
3611 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3612 // initialized in fewer memory operations. Memory words which are
3613 // covered by neither tiles nor non-constant stores are pre-zeroed
3614 // by explicit stores of zero. (The code shape happens to do all
3615 // zeroing first, then all other stores, with both sequences occurring
3616 // in order of ascending offsets.)
3617 //
3618 // Alternatively, code may be inserted between an AllocateNode and its
3619 // InitializeNode, to perform arbitrary initialization of the new object.
3620 // E.g., the object copying intrinsics insert complex data transfers here.
3621 // The initialization must then be marked as 'complete' disable the
3622 // built-in zeroing semantics and the collection of initializing stores.
3623 //
3624 // While an InitializeNode is incomplete, reads from the memory state
3625 // produced by it are optimizable if they match the control edge and
3626 // new oop address associated with the allocation/initialization.
3627 // They return a stored value (if the offset matches) or else zero.
3628 // A write to the memory state, if it matches control and address,
3629 // and if it is to a constant offset, may be 'captured' by the
3630 // InitializeNode. It is cloned as a raw memory operation and rewired
3631 // inside the initialization, to the raw oop produced by the allocation.
3632 // Operations on addresses which are provably distinct (e.g., to
3633 // other AllocateNodes) are allowed to bypass the initialization.
3634 //
3635 // The effect of all this is to consolidate object initialization
3636 // (both arrays and non-arrays, both piecewise and bulk) into a
3637 // single location, where it can be optimized as a unit.
3638 //
3639 // Only stores with an offset less than TrackedInitializationLimit words
3640 // will be considered for capture by an InitializeNode. This puts a
3641 // reasonable limit on the complexity of optimized initializations.
3642
3643 //---------------------------InitializeNode------------------------------------
3644 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3645 : MemBarNode(C, adr_type, rawoop),
3646 _is_complete(Incomplete), _does_not_escape(false)
3647 {
3648 init_class_id(Class_Initialize);
3649
3650 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3651 assert(in(RawAddress) == rawoop, "proper init");
3652 // Note: allocation() can be NULL, for secondary initialization barriers
3653 }
3654
3655 // Since this node is not matched, it will be processed by the
3656 // register allocator. Declare that there are no constraints
3657 // on the allocation of the RawAddress edge.
3658 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3659 // This edge should be set to top, by the set_complete. But be conservative.
3660 if (idx == InitializeNode::RawAddress)
3661 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3662 return RegMask::Empty;
3663 }
3664
3665 Node* InitializeNode::memory(uint alias_idx) {
3666 Node* mem = in(Memory);
3667 if (mem->is_MergeMem()) {
3668 return mem->as_MergeMem()->memory_at(alias_idx);
3669 } else {
3670 // incoming raw memory is not split
3671 return mem;
3672 }
3673 }
3674
3675 bool InitializeNode::is_non_zero() {
3676 if (is_complete()) return false;
3677 remove_extra_zeroes();
3678 return (req() > RawStores);
3679 }
3680
3681 void InitializeNode::set_complete(PhaseGVN* phase) {
3682 assert(!is_complete(), "caller responsibility");
3683 _is_complete = Complete;
3684
3685 // After this node is complete, it contains a bunch of
3686 // raw-memory initializations. There is no need for
3687 // it to have anything to do with non-raw memory effects.
3688 // Therefore, tell all non-raw users to re-optimize themselves,
3689 // after skipping the memory effects of this initialization.
3690 PhaseIterGVN* igvn = phase->is_IterGVN();
3691 if (igvn) igvn->add_users_to_worklist(this);
3692 }
3693
3694 // convenience function
3695 // return false if the init contains any stores already
3696 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3697 InitializeNode* init = initialization();
3698 if (init == NULL || init->is_complete()) return false;
3699 init->remove_extra_zeroes();
3700 // for now, if this allocation has already collected any inits, bail:
3701 if (init->is_non_zero()) return false;
3702 init->set_complete(phase);
3703 return true;
3704 }
3705
3706 void InitializeNode::remove_extra_zeroes() {
3707 if (req() == RawStores) return;
3708 Node* zmem = zero_memory();
3709 uint fill = RawStores;
3710 for (uint i = fill; i < req(); i++) {
3711 Node* n = in(i);
3712 if (n->is_top() || n == zmem) continue; // skip
3713 if (fill < i) set_req(fill, n); // compact
3714 ++fill;
3715 }
3716 // delete any empty spaces created:
3717 while (fill < req()) {
3718 del_req(fill);
3719 }
3720 }
3721
3722 // Helper for remembering which stores go with which offsets.
3723 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3724 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3725 intptr_t offset = -1;
3726 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3727 phase, offset);
3728 if (base == NULL) return -1; // something is dead,
3729 if (offset < 0) return -1; // dead, dead
3730 return offset;
3731 }
3732
3733 // Helper for proving that an initialization expression is
3734 // "simple enough" to be folded into an object initialization.
3735 // Attempts to prove that a store's initial value 'n' can be captured
3736 // within the initialization without creating a vicious cycle, such as:
3737 // { Foo p = new Foo(); p.next = p; }
3738 // True for constants and parameters and small combinations thereof.
3739 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3740 ResourceMark rm;
3741 Unique_Node_List worklist;
3742 worklist.push(value);
3743
3744 uint complexity_limit = 20;
3745 for (uint j = 0; j < worklist.size(); j++) {
3746 if (j >= complexity_limit) {
3747 return false; // Bail out if processed too many nodes
3748 }
3749
3750 Node* n = worklist.at(j);
3751 if (n == NULL) continue; // (can this really happen?)
3752 if (n->is_Proj()) n = n->in(0);
3753 if (n == this) return false; // found a cycle
3754 if (n->is_Con()) continue;
3755 if (n->is_Start()) continue; // params, etc., are OK
3756 if (n->is_Root()) continue; // even better
3757
3758 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3759 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3760 continue;
3761 }
3762
3763 Node* ctl = n->in(0);
3764 if (ctl != NULL && !ctl->is_top()) {
3765 if (ctl->is_Proj()) ctl = ctl->in(0);
3766 if (ctl == this) return false;
3767
3768 // If we already know that the enclosing memory op is pinned right after
3769 // the init, then any control flow that the store has picked up
3770 // must have preceded the init, or else be equal to the init.
3771 // Even after loop optimizations (which might change control edges)
3772 // a store is never pinned *before* the availability of its inputs.
3773 if (!MemNode::all_controls_dominate(n, this))
3774 return false; // failed to prove a good control
3775 }
3776
3777 // Check data edges for possible dependencies on 'this'.
3778 for (uint i = 1; i < n->req(); i++) {
3779 Node* m = n->in(i);
3780 if (m == NULL || m == n || m->is_top()) continue;
3781
3782 // Only process data inputs once
3783 worklist.push(m);
3784 }
3785 }
3786
3787 return true;
3788 }
3789
3790 // Here are all the checks a Store must pass before it can be moved into
3791 // an initialization. Returns zero if a check fails.
3792 // On success, returns the (constant) offset to which the store applies,
3793 // within the initialized memory.
3794 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3795 const int FAIL = 0;
3796 if (st->req() != MemNode::ValueIn + 1)
3797 return FAIL; // an inscrutable StoreNode (card mark?)
3798 Node* ctl = st->in(MemNode::Control);
3799 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3800 return FAIL; // must be unconditional after the initialization
3801 Node* mem = st->in(MemNode::Memory);
3802 if (!(mem->is_Proj() && mem->in(0) == this))
3803 return FAIL; // must not be preceded by other stores
3804 Node* adr = st->in(MemNode::Address);
3805 intptr_t offset;
3806 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3807 if (alloc == NULL)
3808 return FAIL; // inscrutable address
3809 if (alloc != allocation())
3810 return FAIL; // wrong allocation! (store needs to float up)
3811 int size_in_bytes = st->memory_size();
3812 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3813 return FAIL; // mismatched access
3814 }
3815 Node* val = st->in(MemNode::ValueIn);
3816
3817 if (!detect_init_independence(val, phase))
3818 return FAIL; // stored value must be 'simple enough'
3819
3820 // The Store can be captured only if nothing after the allocation
3821 // and before the Store is using the memory location that the store
3822 // overwrites.
3823 bool failed = false;
3824 // If is_complete_with_arraycopy() is true the shape of the graph is
3825 // well defined and is safe so no need for extra checks.
3826 if (!is_complete_with_arraycopy()) {
3827 // We are going to look at each use of the memory state following
3828 // the allocation to make sure nothing reads the memory that the
3829 // Store writes.
3830 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3831 int alias_idx = phase->C->get_alias_index(t_adr);
3832 ResourceMark rm;
3833 Unique_Node_List mems;
3834 mems.push(mem);
3835 Node* unique_merge = NULL;
3836 for (uint next = 0; next < mems.size(); ++next) {
3837 Node *m = mems.at(next);
3838 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3839 Node *n = m->fast_out(j);
3840 if (n->outcnt() == 0) {
3841 continue;
3842 }
3843 if (n == st) {
3844 continue;
3845 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3846 // If the control of this use is different from the control
3847 // of the Store which is right after the InitializeNode then
3848 // this node cannot be between the InitializeNode and the
3849 // Store.
3850 continue;
3851 } else if (n->is_MergeMem()) {
3852 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3853 // We can hit a MergeMemNode (that will likely go away
3854 // later) that is a direct use of the memory state
3855 // following the InitializeNode on the same slice as the
3856 // store node that we'd like to capture. We need to check
3857 // the uses of the MergeMemNode.
3858 mems.push(n);
3859 }
3860 } else if (n->is_Mem()) {
3861 Node* other_adr = n->in(MemNode::Address);
3862 if (other_adr == adr) {
3863 failed = true;
3864 break;
3865 } else {
3866 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3867 if (other_t_adr != NULL) {
3868 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3869 if (other_alias_idx == alias_idx) {
3870 // A load from the same memory slice as the store right
3871 // after the InitializeNode. We check the control of the
3872 // object/array that is loaded from. If it's the same as
3873 // the store control then we cannot capture the store.
3874 assert(!n->is_Store(), "2 stores to same slice on same control?");
3875 Node* base = other_adr;
3876 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3877 base = base->in(AddPNode::Base);
3878 if (base != NULL) {
3879 base = base->uncast();
3880 if (base->is_Proj() && base->in(0) == alloc) {
3881 failed = true;
3882 break;
3883 }
3884 }
3885 }
3886 }
3887 }
3888 } else {
3889 failed = true;
3890 break;
3891 }
3892 }
3893 }
3894 }
3895 if (failed) {
3896 if (!can_reshape) {
3897 // We decided we couldn't capture the store during parsing. We
3898 // should try again during the next IGVN once the graph is
3899 // cleaner.
3900 phase->C->record_for_igvn(st);
3901 }
3902 return FAIL;
3903 }
3904
3905 return offset; // success
3906 }
3907
3908 // Find the captured store in(i) which corresponds to the range
3909 // [start..start+size) in the initialized object.
3910 // If there is one, return its index i. If there isn't, return the
3911 // negative of the index where it should be inserted.
3912 // Return 0 if the queried range overlaps an initialization boundary
3913 // or if dead code is encountered.
3914 // If size_in_bytes is zero, do not bother with overlap checks.
3915 int InitializeNode::captured_store_insertion_point(intptr_t start,
3916 int size_in_bytes,
3917 PhaseTransform* phase) {
3918 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
3919
3920 if (is_complete())
3921 return FAIL; // arraycopy got here first; punt
3922
3923 assert(allocation() != NULL, "must be present");
3924
3925 // no negatives, no header fields:
3926 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3927
3928 // after a certain size, we bail out on tracking all the stores:
3929 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3930 if (start >= ti_limit) return FAIL;
3931
3932 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3933 if (i >= limit) return -(int)i; // not found; here is where to put it
3934
3935 Node* st = in(i);
3936 intptr_t st_off = get_store_offset(st, phase);
3937 if (st_off < 0) {
3938 if (st != zero_memory()) {
3939 return FAIL; // bail out if there is dead garbage
3940 }
3941 } else if (st_off > start) {
3942 // ...we are done, since stores are ordered
3943 if (st_off < start + size_in_bytes) {
3944 return FAIL; // the next store overlaps
3945 }
3946 return -(int)i; // not found; here is where to put it
3947 } else if (st_off < start) {
3948 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
3949 if (size_in_bytes != 0 &&
3950 start < st_off + MAX_STORE &&
3951 start < st_off + st->as_Store()->memory_size()) {
3952 return FAIL; // the previous store overlaps
3953 }
3954 } else {
3955 if (size_in_bytes != 0 &&
3956 st->as_Store()->memory_size() != size_in_bytes) {
3957 return FAIL; // mismatched store size
3958 }
3959 return i;
3960 }
3961
3962 ++i;
3963 }
3964 }
3965
3966 // Look for a captured store which initializes at the offset 'start'
3967 // with the given size. If there is no such store, and no other
3968 // initialization interferes, then return zero_memory (the memory
3969 // projection of the AllocateNode).
3970 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3971 PhaseTransform* phase) {
3972 assert(stores_are_sane(phase), "");
3973 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3974 if (i == 0) {
3975 return NULL; // something is dead
3976 } else if (i < 0) {
3977 return zero_memory(); // just primordial zero bits here
3978 } else {
3979 Node* st = in(i); // here is the store at this position
3980 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3981 return st;
3982 }
3983 }
3984
3985 // Create, as a raw pointer, an address within my new object at 'offset'.
3986 Node* InitializeNode::make_raw_address(intptr_t offset,
3987 PhaseTransform* phase) {
3988 Node* addr = in(RawAddress);
3989 if (offset != 0) {
3990 Compile* C = phase->C;
3991 addr = phase->transform( new AddPNode(C->top(), addr,
3992 phase->MakeConX(offset)) );
3993 }
3994 return addr;
3995 }
3996
3997 // Clone the given store, converting it into a raw store
3998 // initializing a field or element of my new object.
3999 // Caller is responsible for retiring the original store,
4000 // with subsume_node or the like.
4001 //
4002 // From the example above InitializeNode::InitializeNode,
4003 // here are the old stores to be captured:
4004 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4005 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4006 //
4007 // Here is the changed code; note the extra edges on init:
4008 // alloc = (Allocate ...)
4009 // rawoop = alloc.RawAddress
4010 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4011 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4012 // init = (Initialize alloc.Control alloc.Memory rawoop
4013 // rawstore1 rawstore2)
4014 //
4015 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4016 PhaseGVN* phase, bool can_reshape) {
4017 assert(stores_are_sane(phase), "");
4018
4019 if (start < 0) return NULL;
4020 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4021
4022 Compile* C = phase->C;
4023 int size_in_bytes = st->memory_size();
4024 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4025 if (i == 0) return NULL; // bail out
4026 Node* prev_mem = NULL; // raw memory for the captured store
4027 if (i > 0) {
4028 prev_mem = in(i); // there is a pre-existing store under this one
4029 set_req(i, C->top()); // temporarily disconnect it
4030 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4031 } else {
4032 i = -i; // no pre-existing store
4033 prev_mem = zero_memory(); // a slice of the newly allocated object
4034 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4035 set_req(--i, C->top()); // reuse this edge; it has been folded away
4036 else
4037 ins_req(i, C->top()); // build a new edge
4038 }
4039 Node* new_st = st->clone();
4040 new_st->set_req(MemNode::Control, in(Control));
4041 new_st->set_req(MemNode::Memory, prev_mem);
4042 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4043 new_st = phase->transform(new_st);
4044
4045 // At this point, new_st might have swallowed a pre-existing store
4046 // at the same offset, or perhaps new_st might have disappeared,
4047 // if it redundantly stored the same value (or zero to fresh memory).
4048
4049 // In any case, wire it in:
4050 PhaseIterGVN* igvn = phase->is_IterGVN();
4051 if (igvn) {
4052 igvn->rehash_node_delayed(this);
4053 }
4054 set_req(i, new_st);
4055
4056 // The caller may now kill the old guy.
4057 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4058 assert(check_st == new_st || check_st == NULL, "must be findable");
4059 assert(!is_complete(), "");
4060 return new_st;
4061 }
4062
4063 static bool store_constant(jlong* tiles, int num_tiles,
4064 intptr_t st_off, int st_size,
4065 jlong con) {
4066 if ((st_off & (st_size-1)) != 0)
4067 return false; // strange store offset (assume size==2**N)
4068 address addr = (address)tiles + st_off;
4069 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4070 switch (st_size) {
4071 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4072 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4073 case sizeof(jint): *(jint*) addr = (jint) con; break;
4074 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4075 default: return false; // strange store size (detect size!=2**N here)
4076 }
4077 return true; // return success to caller
4078 }
4079
4080 // Coalesce subword constants into int constants and possibly
4081 // into long constants. The goal, if the CPU permits,
4082 // is to initialize the object with a small number of 64-bit tiles.
4083 // Also, convert floating-point constants to bit patterns.
4084 // Non-constants are not relevant to this pass.
4085 //
4086 // In terms of the running example on InitializeNode::InitializeNode
4087 // and InitializeNode::capture_store, here is the transformation
4088 // of rawstore1 and rawstore2 into rawstore12:
4089 // alloc = (Allocate ...)
4090 // rawoop = alloc.RawAddress
4091 // tile12 = 0x00010002
4092 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4093 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4094 //
4095 void
4096 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4097 Node* size_in_bytes,
4098 PhaseGVN* phase) {
4099 Compile* C = phase->C;
4100
4101 assert(stores_are_sane(phase), "");
4102 // Note: After this pass, they are not completely sane,
4103 // since there may be some overlaps.
4104
4105 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4106
4107 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4108 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4109 size_limit = MIN2(size_limit, ti_limit);
4110 size_limit = align_up(size_limit, BytesPerLong);
4111 int num_tiles = size_limit / BytesPerLong;
4112
4113 // allocate space for the tile map:
4114 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4115 jlong tiles_buf[small_len];
4116 Node* nodes_buf[small_len];
4117 jlong inits_buf[small_len];
4118 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4119 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4120 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4121 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4122 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4123 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4124 // tiles: exact bitwise model of all primitive constants
4125 // nodes: last constant-storing node subsumed into the tiles model
4126 // inits: which bytes (in each tile) are touched by any initializations
4127
4128 //// Pass A: Fill in the tile model with any relevant stores.
4129
4130 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4131 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4132 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4133 Node* zmem = zero_memory(); // initially zero memory state
4134 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4135 Node* st = in(i);
4136 intptr_t st_off = get_store_offset(st, phase);
4137
4138 // Figure out the store's offset and constant value:
4139 if (st_off < header_size) continue; //skip (ignore header)
4140 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4141 int st_size = st->as_Store()->memory_size();
4142 if (st_off + st_size > size_limit) break;
4143
4144 // Record which bytes are touched, whether by constant or not.
4145 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4146 continue; // skip (strange store size)
4147
4148 const Type* val = phase->type(st->in(MemNode::ValueIn));
4149 if (!val->singleton()) continue; //skip (non-con store)
4150 BasicType type = val->basic_type();
4151
4152 jlong con = 0;
4153 switch (type) {
4154 case T_INT: con = val->is_int()->get_con(); break;
4155 case T_LONG: con = val->is_long()->get_con(); break;
4156 case T_FLOAT: con = jint_cast(val->getf()); break;
4157 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4158 default: continue; //skip (odd store type)
4159 }
4160
4161 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4162 st->Opcode() == Op_StoreL) {
4163 continue; // This StoreL is already optimal.
4164 }
4165
4166 // Store down the constant.
4167 store_constant(tiles, num_tiles, st_off, st_size, con);
4168
4169 intptr_t j = st_off >> LogBytesPerLong;
4170
4171 if (type == T_INT && st_size == BytesPerInt
4172 && (st_off & BytesPerInt) == BytesPerInt) {
4173 jlong lcon = tiles[j];
4174 if (!Matcher::isSimpleConstant64(lcon) &&
4175 st->Opcode() == Op_StoreI) {
4176 // This StoreI is already optimal by itself.
4177 jint* intcon = (jint*) &tiles[j];
4178 intcon[1] = 0; // undo the store_constant()
4179
4180 // If the previous store is also optimal by itself, back up and
4181 // undo the action of the previous loop iteration... if we can.
4182 // But if we can't, just let the previous half take care of itself.
4183 st = nodes[j];
4184 st_off -= BytesPerInt;
4185 con = intcon[0];
4186 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4187 assert(st_off >= header_size, "still ignoring header");
4188 assert(get_store_offset(st, phase) == st_off, "must be");
4189 assert(in(i-1) == zmem, "must be");
4190 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4191 assert(con == tcon->is_int()->get_con(), "must be");
4192 // Undo the effects of the previous loop trip, which swallowed st:
4193 intcon[0] = 0; // undo store_constant()
4194 set_req(i-1, st); // undo set_req(i, zmem)
4195 nodes[j] = NULL; // undo nodes[j] = st
4196 --old_subword; // undo ++old_subword
4197 }
4198 continue; // This StoreI is already optimal.
4199 }
4200 }
4201
4202 // This store is not needed.
4203 set_req(i, zmem);
4204 nodes[j] = st; // record for the moment
4205 if (st_size < BytesPerLong) // something has changed
4206 ++old_subword; // includes int/float, but who's counting...
4207 else ++old_long;
4208 }
4209
4210 if ((old_subword + old_long) == 0)
4211 return; // nothing more to do
4212
4213 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4214 // Be sure to insert them before overlapping non-constant stores.
4215 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4216 for (int j = 0; j < num_tiles; j++) {
4217 jlong con = tiles[j];
4218 jlong init = inits[j];
4219 if (con == 0) continue;
4220 jint con0, con1; // split the constant, address-wise
4221 jint init0, init1; // split the init map, address-wise
4222 { union { jlong con; jint intcon[2]; } u;
4223 u.con = con;
4224 con0 = u.intcon[0];
4225 con1 = u.intcon[1];
4226 u.con = init;
4227 init0 = u.intcon[0];
4228 init1 = u.intcon[1];
4229 }
4230
4231 Node* old = nodes[j];
4232 assert(old != NULL, "need the prior store");
4233 intptr_t offset = (j * BytesPerLong);
4234
4235 bool split = !Matcher::isSimpleConstant64(con);
4236
4237 if (offset < header_size) {
4238 assert(offset + BytesPerInt >= header_size, "second int counts");
4239 assert(*(jint*)&tiles[j] == 0, "junk in header");
4240 split = true; // only the second word counts
4241 // Example: int a[] = { 42 ... }
4242 } else if (con0 == 0 && init0 == -1) {
4243 split = true; // first word is covered by full inits
4244 // Example: int a[] = { ... foo(), 42 ... }
4245 } else if (con1 == 0 && init1 == -1) {
4246 split = true; // second word is covered by full inits
4247 // Example: int a[] = { ... 42, foo() ... }
4248 }
4249
4250 // Here's a case where init0 is neither 0 nor -1:
4251 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4252 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4253 // In this case the tile is not split; it is (jlong)42.
4254 // The big tile is stored down, and then the foo() value is inserted.
4255 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4256
4257 Node* ctl = old->in(MemNode::Control);
4258 Node* adr = make_raw_address(offset, phase);
4259 const TypePtr* atp = TypeRawPtr::BOTTOM;
4260
4261 // One or two coalesced stores to plop down.
4262 Node* st[2];
4263 intptr_t off[2];
4264 int nst = 0;
4265 if (!split) {
4266 ++new_long;
4267 off[nst] = offset;
4268 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4269 phase->longcon(con), T_LONG, MemNode::unordered);
4270 } else {
4271 // Omit either if it is a zero.
4272 if (con0 != 0) {
4273 ++new_int;
4274 off[nst] = offset;
4275 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4276 phase->intcon(con0), T_INT, MemNode::unordered);
4277 }
4278 if (con1 != 0) {
4279 ++new_int;
4280 offset += BytesPerInt;
4281 adr = make_raw_address(offset, phase);
4282 off[nst] = offset;
4283 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4284 phase->intcon(con1), T_INT, MemNode::unordered);
4285 }
4286 }
4287
4288 // Insert second store first, then the first before the second.
4289 // Insert each one just before any overlapping non-constant stores.
4290 while (nst > 0) {
4291 Node* st1 = st[--nst];
4292 C->copy_node_notes_to(st1, old);
4293 st1 = phase->transform(st1);
4294 offset = off[nst];
4295 assert(offset >= header_size, "do not smash header");
4296 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4297 guarantee(ins_idx != 0, "must re-insert constant store");
4298 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4299 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4300 set_req(--ins_idx, st1);
4301 else
4302 ins_req(ins_idx, st1);
4303 }
4304 }
4305
4306 if (PrintCompilation && WizardMode)
4307 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4308 old_subword, old_long, new_int, new_long);
4309 if (C->log() != NULL)
4310 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4311 old_subword, old_long, new_int, new_long);
4312
4313 // Clean up any remaining occurrences of zmem:
4314 remove_extra_zeroes();
4315 }
4316
4317 // Explore forward from in(start) to find the first fully initialized
4318 // word, and return its offset. Skip groups of subword stores which
4319 // together initialize full words. If in(start) is itself part of a
4320 // fully initialized word, return the offset of in(start). If there
4321 // are no following full-word stores, or if something is fishy, return
4322 // a negative value.
4323 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4324 int int_map = 0;
4325 intptr_t int_map_off = 0;
4326 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4327
4328 for (uint i = start, limit = req(); i < limit; i++) {
4329 Node* st = in(i);
4330
4331 intptr_t st_off = get_store_offset(st, phase);
4332 if (st_off < 0) break; // return conservative answer
4333
4334 int st_size = st->as_Store()->memory_size();
4335 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4336 return st_off; // we found a complete word init
4337 }
4338
4339 // update the map:
4340
4341 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4342 if (this_int_off != int_map_off) {
4343 // reset the map:
4344 int_map = 0;
4345 int_map_off = this_int_off;
4346 }
4347
4348 int subword_off = st_off - this_int_off;
4349 int_map |= right_n_bits(st_size) << subword_off;
4350 if ((int_map & FULL_MAP) == FULL_MAP) {
4351 return this_int_off; // we found a complete word init
4352 }
4353
4354 // Did this store hit or cross the word boundary?
4355 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4356 if (next_int_off == this_int_off + BytesPerInt) {
4357 // We passed the current int, without fully initializing it.
4358 int_map_off = next_int_off;
4359 int_map >>= BytesPerInt;
4360 } else if (next_int_off > this_int_off + BytesPerInt) {
4361 // We passed the current and next int.
4362 return this_int_off + BytesPerInt;
4363 }
4364 }
4365
4366 return -1;
4367 }
4368
4369
4370 // Called when the associated AllocateNode is expanded into CFG.
4371 // At this point, we may perform additional optimizations.
4372 // Linearize the stores by ascending offset, to make memory
4373 // activity as coherent as possible.
4374 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4375 intptr_t header_size,
4376 Node* size_in_bytes,
4377 PhaseIterGVN* phase) {
4378 assert(!is_complete(), "not already complete");
4379 assert(stores_are_sane(phase), "");
4380 assert(allocation() != NULL, "must be present");
4381
4382 remove_extra_zeroes();
4383
4384 if (ReduceFieldZeroing || ReduceBulkZeroing)
4385 // reduce instruction count for common initialization patterns
4386 coalesce_subword_stores(header_size, size_in_bytes, phase);
4387
4388 Node* zmem = zero_memory(); // initially zero memory state
4389 Node* inits = zmem; // accumulating a linearized chain of inits
4390 #ifdef ASSERT
4391 intptr_t first_offset = allocation()->minimum_header_size();
4392 intptr_t last_init_off = first_offset; // previous init offset
4393 intptr_t last_init_end = first_offset; // previous init offset+size
4394 intptr_t last_tile_end = first_offset; // previous tile offset+size
4395 #endif
4396 intptr_t zeroes_done = header_size;
4397
4398 bool do_zeroing = true; // we might give up if inits are very sparse
4399 int big_init_gaps = 0; // how many large gaps have we seen?
4400
4401 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4402 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4403
4404 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4405 Node* st = in(i);
4406 intptr_t st_off = get_store_offset(st, phase);
4407 if (st_off < 0)
4408 break; // unknown junk in the inits
4409 if (st->in(MemNode::Memory) != zmem)
4410 break; // complicated store chains somehow in list
4411
4412 int st_size = st->as_Store()->memory_size();
4413 intptr_t next_init_off = st_off + st_size;
4414
4415 if (do_zeroing && zeroes_done < next_init_off) {
4416 // See if this store needs a zero before it or under it.
4417 intptr_t zeroes_needed = st_off;
4418
4419 if (st_size < BytesPerInt) {
4420 // Look for subword stores which only partially initialize words.
4421 // If we find some, we must lay down some word-level zeroes first,
4422 // underneath the subword stores.
4423 //
4424 // Examples:
4425 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4426 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4427 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4428 //
4429 // Note: coalesce_subword_stores may have already done this,
4430 // if it was prompted by constant non-zero subword initializers.
4431 // But this case can still arise with non-constant stores.
4432
4433 intptr_t next_full_store = find_next_fullword_store(i, phase);
4434
4435 // In the examples above:
4436 // in(i) p q r s x y z
4437 // st_off 12 13 14 15 12 13 14
4438 // st_size 1 1 1 1 1 1 1
4439 // next_full_s. 12 16 16 16 16 16 16
4440 // z's_done 12 16 16 16 12 16 12
4441 // z's_needed 12 16 16 16 16 16 16
4442 // zsize 0 0 0 0 4 0 4
4443 if (next_full_store < 0) {
4444 // Conservative tack: Zero to end of current word.
4445 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4446 } else {
4447 // Zero to beginning of next fully initialized word.
4448 // Or, don't zero at all, if we are already in that word.
4449 assert(next_full_store >= zeroes_needed, "must go forward");
4450 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4451 zeroes_needed = next_full_store;
4452 }
4453 }
4454
4455 if (zeroes_needed > zeroes_done) {
4456 intptr_t zsize = zeroes_needed - zeroes_done;
4457 // Do some incremental zeroing on rawmem, in parallel with inits.
4458 zeroes_done = align_down(zeroes_done, BytesPerInt);
4459 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4460 zeroes_done, zeroes_needed,
4461 phase);
4462 zeroes_done = zeroes_needed;
4463 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4464 do_zeroing = false; // leave the hole, next time
4465 }
4466 }
4467
4468 // Collect the store and move on:
4469 phase->replace_input_of(st, MemNode::Memory, inits);
4470 inits = st; // put it on the linearized chain
4471 set_req(i, zmem); // unhook from previous position
4472
4473 if (zeroes_done == st_off)
4474 zeroes_done = next_init_off;
4475
4476 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4477
4478 #ifdef ASSERT
4479 // Various order invariants. Weaker than stores_are_sane because
4480 // a large constant tile can be filled in by smaller non-constant stores.
4481 assert(st_off >= last_init_off, "inits do not reverse");
4482 last_init_off = st_off;
4483 const Type* val = NULL;
4484 if (st_size >= BytesPerInt &&
4485 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4486 (int)val->basic_type() < (int)T_OBJECT) {
4487 assert(st_off >= last_tile_end, "tiles do not overlap");
4488 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4489 last_tile_end = MAX2(last_tile_end, next_init_off);
4490 } else {
4491 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4492 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4493 assert(st_off >= last_init_end, "inits do not overlap");
4494 last_init_end = next_init_off; // it's a non-tile
4495 }
4496 #endif //ASSERT
4497 }
4498
4499 remove_extra_zeroes(); // clear out all the zmems left over
4500 add_req(inits);
4501
4502 if (!(UseTLAB && ZeroTLAB)) {
4503 // If anything remains to be zeroed, zero it all now.
4504 zeroes_done = align_down(zeroes_done, BytesPerInt);
4505 // if it is the last unused 4 bytes of an instance, forget about it
4506 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4507 if (zeroes_done + BytesPerLong >= size_limit) {
4508 AllocateNode* alloc = allocation();
4509 assert(alloc != NULL, "must be present");
4510 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4511 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4512 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4513 if (zeroes_done == k->layout_helper())
4514 zeroes_done = size_limit;
4515 }
4516 }
4517 if (zeroes_done < size_limit) {
4518 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4519 zeroes_done, size_in_bytes, phase);
4520 }
4521 }
4522
4523 set_complete(phase);
4524 return rawmem;
4525 }
4526
4527
4528 #ifdef ASSERT
4529 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4530 if (is_complete())
4531 return true; // stores could be anything at this point
4532 assert(allocation() != NULL, "must be present");
4533 intptr_t last_off = allocation()->minimum_header_size();
4534 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4535 Node* st = in(i);
4536 intptr_t st_off = get_store_offset(st, phase);
4537 if (st_off < 0) continue; // ignore dead garbage
4538 if (last_off > st_off) {
4539 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4540 this->dump(2);
4541 assert(false, "ascending store offsets");
4542 return false;
4543 }
4544 last_off = st_off + st->as_Store()->memory_size();
4545 }
4546 return true;
4547 }
4548 #endif //ASSERT
4549
4550
4551
4552
4553 //============================MergeMemNode=====================================
4554 //
4555 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4556 // contributing store or call operations. Each contributor provides the memory
4557 // state for a particular "alias type" (see Compile::alias_type). For example,
4558 // if a MergeMem has an input X for alias category #6, then any memory reference
4559 // to alias category #6 may use X as its memory state input, as an exact equivalent
4560 // to using the MergeMem as a whole.
4561 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4562 //
4563 // (Here, the <N> notation gives the index of the relevant adr_type.)
4564 //
4565 // In one special case (and more cases in the future), alias categories overlap.
4566 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4567 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4568 // it is exactly equivalent to that state W:
4569 // MergeMem(<Bot>: W) <==> W
4570 //
4571 // Usually, the merge has more than one input. In that case, where inputs
4572 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4573 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4574 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4575 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4576 //
4577 // A merge can take a "wide" memory state as one of its narrow inputs.
4578 // This simply means that the merge observes out only the relevant parts of
4579 // the wide input. That is, wide memory states arriving at narrow merge inputs
4580 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4581 //
4582 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4583 // and that memory slices "leak through":
4584 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4585 //
4586 // But, in such a cascade, repeated memory slices can "block the leak":
4587 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4588 //
4589 // In the last example, Y is not part of the combined memory state of the
4590 // outermost MergeMem. The system must, of course, prevent unschedulable
4591 // memory states from arising, so you can be sure that the state Y is somehow
4592 // a precursor to state Y'.
4593 //
4594 //
4595 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4596 // of each MergeMemNode array are exactly the numerical alias indexes, including
4597 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4598 // Compile::alias_type (and kin) produce and manage these indexes.
4599 //
4600 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4601 // (Note that this provides quick access to the top node inside MergeMem methods,
4602 // without the need to reach out via TLS to Compile::current.)
4603 //
4604 // As a consequence of what was just described, a MergeMem that represents a full
4605 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4606 // containing all alias categories.
4607 //
4608 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4609 //
4610 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4611 // a memory state for the alias type <N>, or else the top node, meaning that
4612 // there is no particular input for that alias type. Note that the length of
4613 // a MergeMem is variable, and may be extended at any time to accommodate new
4614 // memory states at larger alias indexes. When merges grow, they are of course
4615 // filled with "top" in the unused in() positions.
4616 //
4617 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4618 // (Top was chosen because it works smoothly with passes like GCM.)
4619 //
4620 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4621 // the type of random VM bits like TLS references.) Since it is always the
4622 // first non-Bot memory slice, some low-level loops use it to initialize an
4623 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4624 //
4625 //
4626 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4627 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4628 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4629 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4630 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4631 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4632 //
4633 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4634 // really that different from the other memory inputs. An abbreviation called
4635 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4636 //
4637 //
4638 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4639 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4640 // that "emerges though" the base memory will be marked as excluding the alias types
4641 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4642 //
4643 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4644 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4645 //
4646 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4647 // (It is currently unimplemented.) As you can see, the resulting merge is
4648 // actually a disjoint union of memory states, rather than an overlay.
4649 //
4650
4651 //------------------------------MergeMemNode-----------------------------------
4652 Node* MergeMemNode::make_empty_memory() {
4653 Node* empty_memory = (Node*) Compile::current()->top();
4654 assert(empty_memory->is_top(), "correct sentinel identity");
4655 return empty_memory;
4656 }
4657
4658 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4659 init_class_id(Class_MergeMem);
4660 // all inputs are nullified in Node::Node(int)
4661 // set_input(0, NULL); // no control input
4662
4663 // Initialize the edges uniformly to top, for starters.
4664 Node* empty_mem = make_empty_memory();
4665 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4666 init_req(i,empty_mem);
4667 }
4668 assert(empty_memory() == empty_mem, "");
4669
4670 if( new_base != NULL && new_base->is_MergeMem() ) {
4671 MergeMemNode* mdef = new_base->as_MergeMem();
4672 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4673 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4674 mms.set_memory(mms.memory2());
4675 }
4676 assert(base_memory() == mdef->base_memory(), "");
4677 } else {
4678 set_base_memory(new_base);
4679 }
4680 }
4681
4682 // Make a new, untransformed MergeMem with the same base as 'mem'.
4683 // If mem is itself a MergeMem, populate the result with the same edges.
4684 MergeMemNode* MergeMemNode::make(Node* mem) {
4685 return new MergeMemNode(mem);
4686 }
4687
4688 //------------------------------cmp--------------------------------------------
4689 uint MergeMemNode::hash() const { return NO_HASH; }
4690 bool MergeMemNode::cmp( const Node &n ) const {
4691 return (&n == this); // Always fail except on self
4692 }
4693
4694 //------------------------------Identity---------------------------------------
4695 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4696 // Identity if this merge point does not record any interesting memory
4697 // disambiguations.
4698 Node* base_mem = base_memory();
4699 Node* empty_mem = empty_memory();
4700 if (base_mem != empty_mem) { // Memory path is not dead?
4701 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4702 Node* mem = in(i);
4703 if (mem != empty_mem && mem != base_mem) {
4704 return this; // Many memory splits; no change
4705 }
4706 }
4707 }
4708 return base_mem; // No memory splits; ID on the one true input
4709 }
4710
4711 //------------------------------Ideal------------------------------------------
4712 // This method is invoked recursively on chains of MergeMem nodes
4713 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4714 // Remove chain'd MergeMems
4715 //
4716 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4717 // relative to the "in(Bot)". Since we are patching both at the same time,
4718 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4719 // but rewrite each "in(i)" relative to the new "in(Bot)".
4720 Node *progress = NULL;
4721
4722
4723 Node* old_base = base_memory();
4724 Node* empty_mem = empty_memory();
4725 if (old_base == empty_mem)
4726 return NULL; // Dead memory path.
4727
4728 MergeMemNode* old_mbase;
4729 if (old_base != NULL && old_base->is_MergeMem())
4730 old_mbase = old_base->as_MergeMem();
4731 else
4732 old_mbase = NULL;
4733 Node* new_base = old_base;
4734
4735 // simplify stacked MergeMems in base memory
4736 if (old_mbase) new_base = old_mbase->base_memory();
4737
4738 // the base memory might contribute new slices beyond my req()
4739 if (old_mbase) grow_to_match(old_mbase);
4740
4741 // Look carefully at the base node if it is a phi.
4742 PhiNode* phi_base;
4743 if (new_base != NULL && new_base->is_Phi())
4744 phi_base = new_base->as_Phi();
4745 else
4746 phi_base = NULL;
4747
4748 Node* phi_reg = NULL;
4749 uint phi_len = (uint)-1;
4750 if (phi_base != NULL) {
4751 phi_reg = phi_base->region();
4752 phi_len = phi_base->req();
4753 // see if the phi is unfinished
4754 for (uint i = 1; i < phi_len; i++) {
4755 if (phi_base->in(i) == NULL) {
4756 // incomplete phi; do not look at it yet!
4757 phi_reg = NULL;
4758 phi_len = (uint)-1;
4759 break;
4760 }
4761 }
4762 }
4763
4764 // Note: We do not call verify_sparse on entry, because inputs
4765 // can normalize to the base_memory via subsume_node or similar
4766 // mechanisms. This method repairs that damage.
4767
4768 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4769
4770 // Look at each slice.
4771 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4772 Node* old_in = in(i);
4773 // calculate the old memory value
4774 Node* old_mem = old_in;
4775 if (old_mem == empty_mem) old_mem = old_base;
4776 assert(old_mem == memory_at(i), "");
4777
4778 // maybe update (reslice) the old memory value
4779
4780 // simplify stacked MergeMems
4781 Node* new_mem = old_mem;
4782 MergeMemNode* old_mmem;
4783 if (old_mem != NULL && old_mem->is_MergeMem())
4784 old_mmem = old_mem->as_MergeMem();
4785 else
4786 old_mmem = NULL;
4787 if (old_mmem == this) {
4788 // This can happen if loops break up and safepoints disappear.
4789 // A merge of BotPtr (default) with a RawPtr memory derived from a
4790 // safepoint can be rewritten to a merge of the same BotPtr with
4791 // the BotPtr phi coming into the loop. If that phi disappears
4792 // also, we can end up with a self-loop of the mergemem.
4793 // In general, if loops degenerate and memory effects disappear,
4794 // a mergemem can be left looking at itself. This simply means
4795 // that the mergemem's default should be used, since there is
4796 // no longer any apparent effect on this slice.
4797 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4798 // from start. Update the input to TOP.
4799 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4800 }
4801 else if (old_mmem != NULL) {
4802 new_mem = old_mmem->memory_at(i);
4803 }
4804 // else preceding memory was not a MergeMem
4805
4806 // maybe store down a new value
4807 Node* new_in = new_mem;
4808 if (new_in == new_base) new_in = empty_mem;
4809
4810 if (new_in != old_in) {
4811 // Warning: Do not combine this "if" with the previous "if"
4812 // A memory slice might have be be rewritten even if it is semantically
4813 // unchanged, if the base_memory value has changed.
4814 set_req_X(i, new_in, phase);
4815 progress = this; // Report progress
4816 }
4817 }
4818
4819 if (new_base != old_base) {
4820 set_req_X(Compile::AliasIdxBot, new_base, phase);
4821 // Don't use set_base_memory(new_base), because we need to update du.
4822 assert(base_memory() == new_base, "");
4823 progress = this;
4824 }
4825
4826 if( base_memory() == this ) {
4827 // a self cycle indicates this memory path is dead
4828 set_req(Compile::AliasIdxBot, empty_mem);
4829 }
4830
4831 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4832 // Recursion must occur after the self cycle check above
4833 if( base_memory()->is_MergeMem() ) {
4834 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4835 Node *m = phase->transform(new_mbase); // Rollup any cycles
4836 if( m != NULL &&
4837 (m->is_top() ||
4838 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4839 // propagate rollup of dead cycle to self
4840 set_req(Compile::AliasIdxBot, empty_mem);
4841 }
4842 }
4843
4844 if( base_memory() == empty_mem ) {
4845 progress = this;
4846 // Cut inputs during Parse phase only.
4847 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4848 if( !can_reshape ) {
4849 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4850 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4851 }
4852 }
4853 }
4854
4855 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4856 // Check if PhiNode::Ideal's "Split phis through memory merges"
4857 // transform should be attempted. Look for this->phi->this cycle.
4858 uint merge_width = req();
4859 if (merge_width > Compile::AliasIdxRaw) {
4860 PhiNode* phi = base_memory()->as_Phi();
4861 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4862 if (phi->in(i) == this) {
4863 phase->is_IterGVN()->_worklist.push(phi);
4864 break;
4865 }
4866 }
4867 }
4868 }
4869
4870 assert(progress || verify_sparse(), "please, no dups of base");
4871 return progress;
4872 }
4873
4874 //-------------------------set_base_memory-------------------------------------
4875 void MergeMemNode::set_base_memory(Node *new_base) {
4876 Node* empty_mem = empty_memory();
4877 set_req(Compile::AliasIdxBot, new_base);
4878 assert(memory_at(req()) == new_base, "must set default memory");
4879 // Clear out other occurrences of new_base:
4880 if (new_base != empty_mem) {
4881 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4882 if (in(i) == new_base) set_req(i, empty_mem);
4883 }
4884 }
4885 }
4886
4887 //------------------------------out_RegMask------------------------------------
4888 const RegMask &MergeMemNode::out_RegMask() const {
4889 return RegMask::Empty;
4890 }
4891
4892 //------------------------------dump_spec--------------------------------------
4893 #ifndef PRODUCT
4894 void MergeMemNode::dump_spec(outputStream *st) const {
4895 st->print(" {");
4896 Node* base_mem = base_memory();
4897 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4898 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4899 if (mem == base_mem) { st->print(" -"); continue; }
4900 st->print( " N%d:", mem->_idx );
4901 Compile::current()->get_adr_type(i)->dump_on(st);
4902 }
4903 st->print(" }");
4904 }
4905 #endif // !PRODUCT
4906
4907
4908 #ifdef ASSERT
4909 static bool might_be_same(Node* a, Node* b) {
4910 if (a == b) return true;
4911 if (!(a->is_Phi() || b->is_Phi())) return false;
4912 // phis shift around during optimization
4913 return true; // pretty stupid...
4914 }
4915
4916 // verify a narrow slice (either incoming or outgoing)
4917 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4918 if (!VerifyAliases) return; // don't bother to verify unless requested
4919 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4920 if (Node::in_dump()) return; // muzzle asserts when printing
4921 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4922 assert(n != NULL, "");
4923 // Elide intervening MergeMem's
4924 while (n->is_MergeMem()) {
4925 n = n->as_MergeMem()->memory_at(alias_idx);
4926 }
4927 Compile* C = Compile::current();
4928 const TypePtr* n_adr_type = n->adr_type();
4929 if (n == m->empty_memory()) {
4930 // Implicit copy of base_memory()
4931 } else if (n_adr_type != TypePtr::BOTTOM) {
4932 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4933 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4934 } else {
4935 // A few places like make_runtime_call "know" that VM calls are narrow,
4936 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4937 bool expected_wide_mem = false;
4938 if (n == m->base_memory()) {
4939 expected_wide_mem = true;
4940 } else if (alias_idx == Compile::AliasIdxRaw ||
4941 n == m->memory_at(Compile::AliasIdxRaw)) {
4942 expected_wide_mem = true;
4943 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4944 // memory can "leak through" calls on channels that
4945 // are write-once. Allow this also.
4946 expected_wide_mem = true;
4947 }
4948 assert(expected_wide_mem, "expected narrow slice replacement");
4949 }
4950 }
4951 #else // !ASSERT
4952 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4953 #endif
4954
4955
4956 //-----------------------------memory_at---------------------------------------
4957 Node* MergeMemNode::memory_at(uint alias_idx) const {
4958 assert(alias_idx >= Compile::AliasIdxRaw ||
4959 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4960 "must avoid base_memory and AliasIdxTop");
4961
4962 // Otherwise, it is a narrow slice.
4963 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4964 Compile *C = Compile::current();
4965 if (is_empty_memory(n)) {
4966 // the array is sparse; empty slots are the "top" node
4967 n = base_memory();
4968 assert(Node::in_dump()
4969 || n == NULL || n->bottom_type() == Type::TOP
4970 || n->adr_type() == NULL // address is TOP
4971 || n->adr_type() == TypePtr::BOTTOM
4972 || n->adr_type() == TypeRawPtr::BOTTOM
4973 || Compile::current()->AliasLevel() == 0,
4974 "must be a wide memory");
4975 // AliasLevel == 0 if we are organizing the memory states manually.
4976 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4977 } else {
4978 // make sure the stored slice is sane
4979 #ifdef ASSERT
4980 if (VMError::is_error_reported() || Node::in_dump()) {
4981 } else if (might_be_same(n, base_memory())) {
4982 // Give it a pass: It is a mostly harmless repetition of the base.
4983 // This can arise normally from node subsumption during optimization.
4984 } else {
4985 verify_memory_slice(this, alias_idx, n);
4986 }
4987 #endif
4988 }
4989 return n;
4990 }
4991
4992 //---------------------------set_memory_at-------------------------------------
4993 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4994 verify_memory_slice(this, alias_idx, n);
4995 Node* empty_mem = empty_memory();
4996 if (n == base_memory()) n = empty_mem; // collapse default
4997 uint need_req = alias_idx+1;
4998 if (req() < need_req) {
4999 if (n == empty_mem) return; // already the default, so do not grow me
5000 // grow the sparse array
5001 do {
5002 add_req(empty_mem);
5003 } while (req() < need_req);
5004 }
5005 set_req( alias_idx, n );
5006 }
5007
5008
5009
5010 //--------------------------iteration_setup------------------------------------
5011 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5012 if (other != NULL) {
5013 grow_to_match(other);
5014 // invariant: the finite support of mm2 is within mm->req()
5015 #ifdef ASSERT
5016 for (uint i = req(); i < other->req(); i++) {
5017 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5018 }
5019 #endif
5020 }
5021 // Replace spurious copies of base_memory by top.
5022 Node* base_mem = base_memory();
5023 if (base_mem != NULL && !base_mem->is_top()) {
5024 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5025 if (in(i) == base_mem)
5026 set_req(i, empty_memory());
5027 }
5028 }
5029 }
5030
5031 //---------------------------grow_to_match-------------------------------------
5032 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5033 Node* empty_mem = empty_memory();
5034 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5035 // look for the finite support of the other memory
5036 for (uint i = other->req(); --i >= req(); ) {
5037 if (other->in(i) != empty_mem) {
5038 uint new_len = i+1;
5039 while (req() < new_len) add_req(empty_mem);
5040 break;
5041 }
5042 }
5043 }
5044
5045 //---------------------------verify_sparse-------------------------------------
5046 #ifndef PRODUCT
5047 bool MergeMemNode::verify_sparse() const {
5048 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5049 Node* base_mem = base_memory();
5050 // The following can happen in degenerate cases, since empty==top.
5051 if (is_empty_memory(base_mem)) return true;
5052 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5053 assert(in(i) != NULL, "sane slice");
5054 if (in(i) == base_mem) return false; // should have been the sentinel value!
5055 }
5056 return true;
5057 }
5058
5059 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5060 Node* n;
5061 n = mm->in(idx);
5062 if (mem == n) return true; // might be empty_memory()
5063 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5064 if (mem == n) return true;
5065 return false;
5066 }
5067 #endif // !PRODUCT