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.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciFlatArrayKlass.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "compiler/compileLog.hpp"
30 #include "gc/shared/barrierSet.hpp"
31 #include "gc/shared/c2/barrierSetC2.hpp"
32 #include "gc/shared/tlab_globals.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "oops/objArrayKlass.hpp"
36 #include "opto/addnode.hpp"
37 #include "opto/arraycopynode.hpp"
38 #include "opto/cfgnode.hpp"
39 #include "opto/regalloc.hpp"
40 #include "opto/compile.hpp"
41 #include "opto/connode.hpp"
42 #include "opto/convertnode.hpp"
43 #include "opto/inlinetypenode.hpp"
44 #include "opto/loopnode.hpp"
45 #include "opto/machnode.hpp"
46 #include "opto/matcher.hpp"
47 #include "opto/memnode.hpp"
48 #include "opto/mulnode.hpp"
49 #include "opto/narrowptrnode.hpp"
50 #include "opto/phaseX.hpp"
51 #include "opto/regmask.hpp"
52 #include "opto/rootnode.hpp"
53 #include "opto/vectornode.hpp"
54 #include "utilities/align.hpp"
55 #include "utilities/copy.hpp"
56 #include "utilities/macros.hpp"
57 #include "utilities/powerOfTwo.hpp"
58 #include "utilities/vmError.hpp"
59
60 // Portions of code courtesy of Clifford Click
61
62 // Optimization - Graph Style
63
64 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
65
66 //=============================================================================
67 uint MemNode::size_of() const { return sizeof(*this); }
68
69 const TypePtr *MemNode::adr_type() const {
70 Node* adr = in(Address);
71 if (adr == NULL) return NULL; // node is dead
72 const TypePtr* cross_check = NULL;
73 DEBUG_ONLY(cross_check = _adr_type);
74 return calculate_adr_type(adr->bottom_type(), cross_check);
75 }
76
77 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
78 if (adr != NULL) {
79 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
80 return true;
81 }
82 }
83 return false;
84 }
85
86 #ifndef PRODUCT
87 void MemNode::dump_spec(outputStream *st) const {
88 if (in(Address) == NULL) return; // node is dead
89 #ifndef ASSERT
90 // fake the missing field
91 const TypePtr* _adr_type = NULL;
92 if (in(Address) != NULL)
93 _adr_type = in(Address)->bottom_type()->isa_ptr();
94 #endif
95 dump_adr_type(this, _adr_type, st);
96
97 Compile* C = Compile::current();
98 if (C->alias_type(_adr_type)->is_volatile()) {
99 st->print(" Volatile!");
100 }
101 if (_unaligned_access) {
102 st->print(" unaligned");
103 }
104 if (_mismatched_access) {
105 st->print(" mismatched");
106 }
107 if (_unsafe_access) {
108 st->print(" unsafe");
109 }
110 }
111
112 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
113 st->print(" @");
114 if (adr_type == NULL) {
115 st->print("NULL");
116 } else {
117 adr_type->dump_on(st);
118 Compile* C = Compile::current();
119 Compile::AliasType* atp = NULL;
120 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
121 if (atp == NULL)
122 st->print(", idx=?\?;");
123 else if (atp->index() == Compile::AliasIdxBot)
124 st->print(", idx=Bot;");
125 else if (atp->index() == Compile::AliasIdxTop)
126 st->print(", idx=Top;");
127 else if (atp->index() == Compile::AliasIdxRaw)
128 st->print(", idx=Raw;");
129 else {
130 ciField* field = atp->field();
131 if (field) {
132 st->print(", name=");
133 field->print_name_on(st);
134 }
135 st->print(", idx=%d;", atp->index());
136 }
137 }
138 }
139
140 extern void print_alias_types();
141
142 #endif
143
144 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
145 assert((t_oop != NULL), "sanity");
146 bool is_instance = t_oop->is_known_instance_field();
147 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
148 (load != NULL) && load->is_Load() &&
149 (phase->is_IterGVN() != NULL);
150 if (!(is_instance || is_boxed_value_load))
151 return mchain; // don't try to optimize non-instance types
152 uint instance_id = t_oop->instance_id();
153 Node *start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
154 Node *prev = NULL;
155 Node *result = mchain;
156 while (prev != result) {
157 prev = result;
158 if (result == start_mem)
159 break; // hit one of our sentinels
160 // skip over a call which does not affect this memory slice
161 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
162 Node *proj_in = result->in(0);
163 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
164 break; // hit one of our sentinels
165 } else if (proj_in->is_Call()) {
166 // ArrayCopyNodes processed here as well
167 CallNode *call = proj_in->as_Call();
168 if (!call->may_modify(t_oop, phase)) { // returns false for instances
169 result = call->in(TypeFunc::Memory);
170 }
171 } else if (proj_in->is_Initialize()) {
172 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
173 // Stop if this is the initialization for the object instance which
174 // contains this memory slice, otherwise skip over it.
175 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
176 break;
177 }
178 if (is_instance) {
179 result = proj_in->in(TypeFunc::Memory);
180 } else if (is_boxed_value_load) {
181 Node* klass = alloc->in(AllocateNode::KlassNode);
182 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
183 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
184 result = proj_in->in(TypeFunc::Memory); // not related allocation
185 }
186 }
187 } else if (proj_in->is_MemBar()) {
188 ArrayCopyNode* ac = NULL;
189 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
190 break;
191 }
192 result = proj_in->in(TypeFunc::Memory);
193 } else {
194 assert(false, "unexpected projection");
195 }
196 } else if (result->is_ClearArray()) {
197 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
198 // Can not bypass initialization of the instance
199 // we are looking for.
200 break;
201 }
202 // Otherwise skip it (the call updated 'result' value).
203 } else if (result->is_MergeMem()) {
204 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
205 }
206 }
207 return result;
208 }
209
210 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
211 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
212 if (t_oop == NULL)
213 return mchain; // don't try to optimize non-oop types
214 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
215 bool is_instance = t_oop->is_known_instance_field();
216 PhaseIterGVN *igvn = phase->is_IterGVN();
217 if (is_instance && igvn != NULL && result->is_Phi()) {
218 PhiNode *mphi = result->as_Phi();
219 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
220 const TypePtr *t = mphi->adr_type();
221 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
222 (t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
223 t->is_oopptr()->cast_to_exactness(true)
224 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
225 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop)) {
226 // clone the Phi with our address type
227 result = mphi->split_out_instance(t_adr, igvn);
228 } else {
229 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
230 }
231 }
232 return result;
233 }
234
235 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
236 uint alias_idx = phase->C->get_alias_index(tp);
237 Node *mem = mmem;
238 #ifdef ASSERT
239 {
240 // Check that current type is consistent with the alias index used during graph construction
241 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
242 bool consistent = adr_check == NULL || adr_check->empty() ||
243 phase->C->must_alias(adr_check, alias_idx );
244 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
245 if( !consistent && adr_check != NULL && !adr_check->empty() &&
246 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
247 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
248 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
249 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
250 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
251 // don't assert if it is dead code.
252 consistent = true;
253 }
254 if( !consistent ) {
255 st->print("alias_idx==%d, adr_check==", alias_idx);
256 if( adr_check == NULL ) {
257 st->print("NULL");
258 } else {
259 adr_check->dump();
260 }
261 st->cr();
262 print_alias_types();
263 assert(consistent, "adr_check must match alias idx");
264 }
265 }
266 #endif
267 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
268 // means an array I have not precisely typed yet. Do not do any
269 // alias stuff with it any time soon.
270 const TypeOopPtr *toop = tp->isa_oopptr();
271 if( tp->base() != Type::AnyPtr &&
272 !(toop &&
273 toop->klass() != NULL &&
274 toop->klass()->is_java_lang_Object() &&
275 toop->offset() == Type::OffsetBot) ) {
276 // compress paths and change unreachable cycles to TOP
277 // If not, we can update the input infinitely along a MergeMem cycle
278 // Equivalent code in PhiNode::Ideal
279 Node* m = phase->transform(mmem);
280 // If transformed to a MergeMem, get the desired slice
281 // Otherwise the returned node represents memory for every slice
282 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
283 // Update input if it is progress over what we have now
284 }
285 return mem;
286 }
287
288 //--------------------------Ideal_common---------------------------------------
289 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
290 // Unhook non-raw memories from complete (macro-expanded) initializations.
291 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
292 // If our control input is a dead region, kill all below the region
293 Node *ctl = in(MemNode::Control);
294 if (ctl && remove_dead_region(phase, can_reshape))
295 return this;
296 ctl = in(MemNode::Control);
297 // Don't bother trying to transform a dead node
298 if (ctl && ctl->is_top()) return NodeSentinel;
299
300 PhaseIterGVN *igvn = phase->is_IterGVN();
301 // Wait if control on the worklist.
302 if (ctl && can_reshape && igvn != NULL) {
303 Node* bol = NULL;
304 Node* cmp = NULL;
305 if (ctl->in(0)->is_If()) {
306 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
307 bol = ctl->in(0)->in(1);
308 if (bol->is_Bool())
309 cmp = ctl->in(0)->in(1)->in(1);
310 }
311 if (igvn->_worklist.member(ctl) ||
312 (bol != NULL && igvn->_worklist.member(bol)) ||
313 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
314 // This control path may be dead.
315 // Delay this memory node transformation until the control is processed.
316 igvn->_worklist.push(this);
317 return NodeSentinel; // caller will return NULL
318 }
319 }
320 // Ignore if memory is dead, or self-loop
321 Node *mem = in(MemNode::Memory);
322 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
323 assert(mem != this, "dead loop in MemNode::Ideal");
324
325 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
326 // This memory slice may be dead.
327 // Delay this mem node transformation until the memory is processed.
328 igvn->_worklist.push(this);
329 return NodeSentinel; // caller will return NULL
330 }
331
332 Node *address = in(MemNode::Address);
333 const Type *t_adr = phase->type(address);
334 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
335
336 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
337 // Unsafe off-heap access with zero address. Remove access and other control users
338 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
339 assert(ctl != NULL, "unsafe accesses should be control dependent");
340 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
341 Node* u = ctl->fast_out(i);
342 if (u != ctl) {
343 igvn->rehash_node_delayed(u);
344 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
345 --i, imax -= nb;
346 }
347 }
348 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
349 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
350 phase->C->root()->add_req(halt);
351 return this;
352 }
353
354 if (can_reshape && igvn != NULL &&
355 (igvn->_worklist.member(address) ||
356 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
357 // The address's base and type may change when the address is processed.
358 // Delay this mem node transformation until the address is processed.
359 igvn->_worklist.push(this);
360 return NodeSentinel; // caller will return NULL
361 }
362
363 // Do NOT remove or optimize the next lines: ensure a new alias index
364 // is allocated for an oop pointer type before Escape Analysis.
365 // Note: C++ will not remove it since the call has side effect.
366 if (t_adr->isa_oopptr()) {
367 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
368 }
369
370 Node* base = NULL;
371 if (address->is_AddP()) {
372 base = address->in(AddPNode::Base);
373 }
374 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
375 !t_adr->isa_rawptr()) {
376 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
377 // Skip this node optimization if its address has TOP base.
378 return NodeSentinel; // caller will return NULL
379 }
380
381 // Avoid independent memory operations
382 Node* old_mem = mem;
383
384 // The code which unhooks non-raw memories from complete (macro-expanded)
385 // initializations was removed. After macro-expansion all stores catched
386 // by Initialize node became raw stores and there is no information
387 // which memory slices they modify. So it is unsafe to move any memory
388 // operation above these stores. Also in most cases hooked non-raw memories
389 // were already unhooked by using information from detect_ptr_independence()
390 // and find_previous_store().
391
392 if (mem->is_MergeMem()) {
393 MergeMemNode* mmem = mem->as_MergeMem();
394 const TypePtr *tp = t_adr->is_ptr();
395
396 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
397 }
398
399 if (mem != old_mem) {
400 set_req(MemNode::Memory, mem);
401 if (can_reshape && old_mem->outcnt() == 0 && igvn != NULL) {
402 igvn->_worklist.push(old_mem);
403 }
404 if (phase->type(mem) == Type::TOP) return NodeSentinel;
405 return this;
406 }
407
408 // let the subclass continue analyzing...
409 return NULL;
410 }
411
412 // Helper function for proving some simple control dominations.
413 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
414 // Already assumes that 'dom' is available at 'sub', and that 'sub'
415 // is not a constant (dominated by the method's StartNode).
416 // Used by MemNode::find_previous_store to prove that the
417 // control input of a memory operation predates (dominates)
418 // an allocation it wants to look past.
419 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
420 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
421 return false; // Conservative answer for dead code
422
423 // Check 'dom'. Skip Proj and CatchProj nodes.
424 dom = dom->find_exact_control(dom);
425 if (dom == NULL || dom->is_top())
426 return false; // Conservative answer for dead code
427
428 if (dom == sub) {
429 // For the case when, for example, 'sub' is Initialize and the original
430 // 'dom' is Proj node of the 'sub'.
431 return false;
432 }
433
434 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
435 return true;
436
437 // 'dom' dominates 'sub' if its control edge and control edges
438 // of all its inputs dominate or equal to sub's control edge.
439
440 // Currently 'sub' is either Allocate, Initialize or Start nodes.
441 // Or Region for the check in LoadNode::Ideal();
442 // 'sub' should have sub->in(0) != NULL.
443 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
444 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
445
446 // Get control edge of 'sub'.
447 Node* orig_sub = sub;
448 sub = sub->find_exact_control(sub->in(0));
449 if (sub == NULL || sub->is_top())
450 return false; // Conservative answer for dead code
451
452 assert(sub->is_CFG(), "expecting control");
453
454 if (sub == dom)
455 return true;
456
457 if (sub->is_Start() || sub->is_Root())
458 return false;
459
460 {
461 // Check all control edges of 'dom'.
462
463 ResourceMark rm;
464 Node_List nlist;
465 Unique_Node_List dom_list;
466
467 dom_list.push(dom);
468 bool only_dominating_controls = false;
469
470 for (uint next = 0; next < dom_list.size(); next++) {
471 Node* n = dom_list.at(next);
472 if (n == orig_sub)
473 return false; // One of dom's inputs dominated by sub.
474 if (!n->is_CFG() && n->pinned()) {
475 // Check only own control edge for pinned non-control nodes.
476 n = n->find_exact_control(n->in(0));
477 if (n == NULL || n->is_top())
478 return false; // Conservative answer for dead code
479 assert(n->is_CFG(), "expecting control");
480 dom_list.push(n);
481 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
482 only_dominating_controls = true;
483 } else if (n->is_CFG()) {
484 if (n->dominates(sub, nlist))
485 only_dominating_controls = true;
486 else
487 return false;
488 } else {
489 // First, own control edge.
490 Node* m = n->find_exact_control(n->in(0));
491 if (m != NULL) {
492 if (m->is_top())
493 return false; // Conservative answer for dead code
494 dom_list.push(m);
495 }
496 // Now, the rest of edges.
497 uint cnt = n->req();
498 for (uint i = 1; i < cnt; i++) {
499 m = n->find_exact_control(n->in(i));
500 if (m == NULL || m->is_top())
501 continue;
502 dom_list.push(m);
503 }
504 }
505 }
506 return only_dominating_controls;
507 }
508 }
509
510 //---------------------detect_ptr_independence---------------------------------
511 // Used by MemNode::find_previous_store to prove that two base
512 // pointers are never equal.
513 // The pointers are accompanied by their associated allocations,
514 // if any, which have been previously discovered by the caller.
515 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
516 Node* p2, AllocateNode* a2,
517 PhaseTransform* phase) {
518 // Attempt to prove that these two pointers cannot be aliased.
519 // They may both manifestly be allocations, and they should differ.
520 // Or, if they are not both allocations, they can be distinct constants.
521 // Otherwise, one is an allocation and the other a pre-existing value.
522 if (a1 == NULL && a2 == NULL) { // neither an allocation
523 return (p1 != p2) && p1->is_Con() && p2->is_Con();
524 } else if (a1 != NULL && a2 != NULL) { // both allocations
525 return (a1 != a2);
526 } else if (a1 != NULL) { // one allocation a1
527 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
528 return all_controls_dominate(p2, a1);
529 } else { //(a2 != NULL) // one allocation a2
530 return all_controls_dominate(p1, a2);
531 }
532 return false;
533 }
534
535
536 // Find an arraycopy ac that produces the memory state represented by parameter mem.
537 // Return ac if
538 // (a) can_see_stored_value=true and ac must have set the value for this load or if
539 // (b) can_see_stored_value=false and ac could have set the value for this load or if
540 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
541 // In case (c) change the parameter mem to the memory input of ac to skip it
542 // when searching stored value.
543 // Otherwise return NULL.
544 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
545 ArrayCopyNode* ac = find_array_copy_clone(phase, ld_alloc, mem);
546 if (ac != NULL) {
547 Node* ld_addp = in(MemNode::Address);
548 Node* src = ac->in(ArrayCopyNode::Src);
549 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
550
551 // This is a load from a cloned array. The corresponding arraycopy ac must
552 // have set the value for the load and we can return ac but only if the load
553 // is known to be within bounds. This is checked below.
554 if (ary_t != NULL && ld_addp->is_AddP()) {
555 Node* ld_offs = ld_addp->in(AddPNode::Offset);
556 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
557 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
558 jlong elemsize = type2aelembytes(ary_elem);
559
560 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
561 const TypeInt* sizetype = ary_t->size();
562
563 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
564 // The load is known to be within bounds. It receives its value from ac.
565 return ac;
566 }
567 // The load is known to be out-of-bounds.
568 }
569 // The load could be out-of-bounds. It must not be hoisted but must remain
570 // dependent on the runtime range check. This is achieved by returning NULL.
571 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
572 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
573
574 if (ac->is_arraycopy_validated() ||
575 ac->is_copyof_validated() ||
576 ac->is_copyofrange_validated()) {
577 Node* ld_addp = in(MemNode::Address);
578 if (ld_addp->is_AddP()) {
579 Node* ld_base = ld_addp->in(AddPNode::Address);
580 Node* ld_offs = ld_addp->in(AddPNode::Offset);
581
582 Node* dest = ac->in(ArrayCopyNode::Dest);
583
584 if (dest == ld_base) {
585 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
586 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
587 return ac;
588 }
589 if (!can_see_stored_value) {
590 mem = ac->in(TypeFunc::Memory);
591 return ac;
592 }
593 }
594 }
595 }
596 }
597 return NULL;
598 }
599
600 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseTransform* phase, Node* ld_alloc, Node* mem) const {
601 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
602 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
603 if (ld_alloc != NULL) {
604 // Check if there is an array copy for a clone
605 Node* mb = mem->in(0);
606 ArrayCopyNode* ac = NULL;
607 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
608 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
609 ac = mb->in(0)->in(0)->as_ArrayCopy();
610 } else {
611 // Step over GC barrier when ReduceInitialCardMarks is disabled
612 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
613 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
614
615 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
616 ac = control_proj_ac->in(0)->as_ArrayCopy();
617 }
618 }
619
620 if (ac != NULL && ac->is_clonebasic()) {
621 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase);
622 if (alloc != NULL && alloc == ld_alloc) {
623 return ac;
624 }
625 }
626 }
627 }
628 return NULL;
629 }
630
631 // The logic for reordering loads and stores uses four steps:
632 // (a) Walk carefully past stores and initializations which we
633 // can prove are independent of this load.
634 // (b) Observe that the next memory state makes an exact match
635 // with self (load or store), and locate the relevant store.
636 // (c) Ensure that, if we were to wire self directly to the store,
637 // the optimizer would fold it up somehow.
638 // (d) Do the rewiring, and return, depending on some other part of
639 // the optimizer to fold up the load.
640 // This routine handles steps (a) and (b). Steps (c) and (d) are
641 // specific to loads and stores, so they are handled by the callers.
642 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
643 //
644 Node* MemNode::find_previous_store(PhaseTransform* phase) {
645 Node* ctrl = in(MemNode::Control);
646 Node* adr = in(MemNode::Address);
647 intptr_t offset = 0;
648 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
649 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
650
651 if (offset == Type::OffsetBot)
652 return NULL; // cannot unalias unless there are precise offsets
653
654 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
655 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
656
657 intptr_t size_in_bytes = memory_size();
658
659 Node* mem = in(MemNode::Memory); // start searching here...
660
661 int cnt = 50; // Cycle limiter
662 for (;;) { // While we can dance past unrelated stores...
663 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
664
665 Node* prev = mem;
666 if (mem->is_Store()) {
667 Node* st_adr = mem->in(MemNode::Address);
668 intptr_t st_offset = 0;
669 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
670 if (st_base == NULL)
671 break; // inscrutable pointer
672
673 // For raw accesses it's not enough to prove that constant offsets don't intersect.
674 // We need the bases to be the equal in order for the offset check to make sense.
675 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
676 break;
677 }
678
679 if (st_offset != offset && st_offset != Type::OffsetBot) {
680 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
681 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
682 if (st_offset >= offset + size_in_bytes ||
683 st_offset <= offset - MAX_STORE ||
684 st_offset <= offset - mem->as_Store()->memory_size()) {
685 // Success: The offsets are provably independent.
686 // (You may ask, why not just test st_offset != offset and be done?
687 // The answer is that stores of different sizes can co-exist
688 // in the same sequence of RawMem effects. We sometimes initialize
689 // a whole 'tile' of array elements with a single jint or jlong.)
690 mem = mem->in(MemNode::Memory);
691 continue; // (a) advance through independent store memory
692 }
693 }
694 if (st_base != base &&
695 detect_ptr_independence(base, alloc,
696 st_base,
697 AllocateNode::Ideal_allocation(st_base, phase),
698 phase)) {
699 // Success: The bases are provably independent.
700 mem = mem->in(MemNode::Memory);
701 continue; // (a) advance through independent store memory
702 }
703
704 // (b) At this point, if the bases or offsets do not agree, we lose,
705 // since we have not managed to prove 'this' and 'mem' independent.
706 if (st_base == base && st_offset == offset) {
707 return mem; // let caller handle steps (c), (d)
708 }
709
710 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
711 InitializeNode* st_init = mem->in(0)->as_Initialize();
712 AllocateNode* st_alloc = st_init->allocation();
713 if (st_alloc == NULL)
714 break; // something degenerated
715 bool known_identical = false;
716 bool known_independent = false;
717 if (alloc == st_alloc)
718 known_identical = true;
719 else if (alloc != NULL)
720 known_independent = true;
721 else if (all_controls_dominate(this, st_alloc))
722 known_independent = true;
723
724 if (known_independent) {
725 // The bases are provably independent: Either they are
726 // manifestly distinct allocations, or else the control
727 // of this load dominates the store's allocation.
728 int alias_idx = phase->C->get_alias_index(adr_type());
729 if (alias_idx == Compile::AliasIdxRaw) {
730 mem = st_alloc->in(TypeFunc::Memory);
731 } else {
732 mem = st_init->memory(alias_idx);
733 }
734 continue; // (a) advance through independent store memory
735 }
736
737 // (b) at this point, if we are not looking at a store initializing
738 // the same allocation we are loading from, we lose.
739 if (known_identical) {
740 // From caller, can_see_stored_value will consult find_captured_store.
741 return mem; // let caller handle steps (c), (d)
742 }
743
744 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
745 if (prev != mem) {
746 // Found an arraycopy but it doesn't affect that load
747 continue;
748 }
749 // Found an arraycopy that may affect that load
750 return mem;
751 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
752 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
753 if (mem->is_Proj() && mem->in(0)->is_Call()) {
754 // ArrayCopyNodes processed here as well.
755 CallNode *call = mem->in(0)->as_Call();
756 if (!call->may_modify(addr_t, phase)) {
757 mem = call->in(TypeFunc::Memory);
758 continue; // (a) advance through independent call memory
759 }
760 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
761 ArrayCopyNode* ac = NULL;
762 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
763 break;
764 }
765 mem = mem->in(0)->in(TypeFunc::Memory);
766 continue; // (a) advance through independent MemBar memory
767 } else if (mem->is_ClearArray()) {
768 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
769 // (the call updated 'mem' value)
770 continue; // (a) advance through independent allocation memory
771 } else {
772 // Can not bypass initialization of the instance
773 // we are looking for.
774 return mem;
775 }
776 } else if (mem->is_MergeMem()) {
777 int alias_idx = phase->C->get_alias_index(adr_type());
778 mem = mem->as_MergeMem()->memory_at(alias_idx);
779 continue; // (a) advance through independent MergeMem memory
780 }
781 }
782
783 // Unless there is an explicit 'continue', we must bail out here,
784 // because 'mem' is an inscrutable memory state (e.g., a call).
785 break;
786 }
787
788 return NULL; // bail out
789 }
790
791 //----------------------calculate_adr_type-------------------------------------
792 // Helper function. Notices when the given type of address hits top or bottom.
793 // Also, asserts a cross-check of the type against the expected address type.
794 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
795 if (t == Type::TOP) return NULL; // does not touch memory any more?
796 #ifdef ASSERT
797 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
798 #endif
799 const TypePtr* tp = t->isa_ptr();
800 if (tp == NULL) {
801 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
802 return TypePtr::BOTTOM; // touches lots of memory
803 } else {
804 #ifdef ASSERT
805 // %%%% [phh] We don't check the alias index if cross_check is
806 // TypeRawPtr::BOTTOM. Needs to be investigated.
807 if (cross_check != NULL &&
808 cross_check != TypePtr::BOTTOM &&
809 cross_check != TypeRawPtr::BOTTOM) {
810 // Recheck the alias index, to see if it has changed (due to a bug).
811 Compile* C = Compile::current();
812 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
813 "must stay in the original alias category");
814 // The type of the address must be contained in the adr_type,
815 // disregarding "null"-ness.
816 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
817 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
818 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
819 "real address must not escape from expected memory type");
820 }
821 #endif
822 return tp;
823 }
824 }
825
826 //=============================================================================
827 // Should LoadNode::Ideal() attempt to remove control edges?
828 bool LoadNode::can_remove_control() const {
829 return true;
830 }
831 uint LoadNode::size_of() const { return sizeof(*this); }
832 bool LoadNode::cmp( const Node &n ) const
833 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
834 const Type *LoadNode::bottom_type() const { return _type; }
835 uint LoadNode::ideal_reg() const {
836 return _type->ideal_reg();
837 }
838
839 #ifndef PRODUCT
840 void LoadNode::dump_spec(outputStream *st) const {
841 MemNode::dump_spec(st);
842 if( !Verbose && !WizardMode ) {
843 // standard dump does this in Verbose and WizardMode
844 st->print(" #"); _type->dump_on(st);
845 }
846 if (!depends_only_on_test()) {
847 st->print(" (does not depend only on test)");
848 }
849 }
850 #endif
851
852 #ifdef ASSERT
853 //----------------------------is_immutable_value-------------------------------
854 // Helper function to allow a raw load without control edge for some cases
855 bool LoadNode::is_immutable_value(Node* adr) {
856 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
857 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
858 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
859 in_bytes(JavaThread::osthread_offset()) ||
860 adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
861 in_bytes(JavaThread::threadObj_offset())));
862 }
863 #endif
864
865 //----------------------------LoadNode::make-----------------------------------
866 // Polymorphic factory method:
867 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo,
868 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
869 Compile* C = gvn.C;
870
871 // sanity check the alias category against the created node type
872 assert(!(adr_type->isa_oopptr() &&
873 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
874 "use LoadKlassNode instead");
875 assert(!(adr_type->isa_aryptr() &&
876 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
877 "use LoadRangeNode instead");
878 // Check control edge of raw loads
879 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
880 // oop will be recorded in oop map if load crosses safepoint
881 rt->isa_oopptr() || is_immutable_value(adr),
882 "raw memory operations should have control edge");
883 LoadNode* load = NULL;
884 switch (bt) {
885 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
886 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
887 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
888 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
889 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
890 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency); break;
891 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
892 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
893 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
894 case T_PRIMITIVE_OBJECT:
895 case T_OBJECT:
896 #ifdef _LP64
897 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
898 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
899 } else
900 #endif
901 {
902 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
903 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
904 }
905 break;
906 default:
907 ShouldNotReachHere();
908 break;
909 }
910 assert(load != NULL, "LoadNode should have been created");
911 if (unaligned) {
912 load->set_unaligned_access();
913 }
914 if (mismatched) {
915 load->set_mismatched_access();
916 }
917 if (unsafe) {
918 load->set_unsafe_access();
919 }
920 load->set_barrier_data(barrier_data);
921 if (load->Opcode() == Op_LoadN) {
922 Node* ld = gvn.transform(load);
923 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
924 }
925
926 return load;
927 }
928
929 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
930 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
931 bool require_atomic = true;
932 LoadLNode* load = new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
933 if (unaligned) {
934 load->set_unaligned_access();
935 }
936 if (mismatched) {
937 load->set_mismatched_access();
938 }
939 if (unsafe) {
940 load->set_unsafe_access();
941 }
942 load->set_barrier_data(barrier_data);
943 return load;
944 }
945
946 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo,
947 ControlDependency control_dependency, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
948 bool require_atomic = true;
949 LoadDNode* load = new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
950 if (unaligned) {
951 load->set_unaligned_access();
952 }
953 if (mismatched) {
954 load->set_mismatched_access();
955 }
956 if (unsafe) {
957 load->set_unsafe_access();
958 }
959 load->set_barrier_data(barrier_data);
960 return load;
961 }
962
963
964
965 //------------------------------hash-------------------------------------------
966 uint LoadNode::hash() const {
967 // unroll addition of interesting fields
968 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
969 }
970
971 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
972 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
973 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
974 bool is_stable_ary = FoldStableValues &&
975 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
976 tp->isa_aryptr()->is_stable();
977
978 return (eliminate_boxing && non_volatile) || is_stable_ary;
979 }
980
981 return false;
982 }
983
984 // Is the value loaded previously stored by an arraycopy? If so return
985 // a load node that reads from the source array so we may be able to
986 // optimize out the ArrayCopy node later.
987 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
988 Node* ld_adr = in(MemNode::Address);
989 intptr_t ld_off = 0;
990 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
991 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
992 if (ac != NULL) {
993 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
994
995 Node* mem = ac->in(TypeFunc::Memory);
996 Node* ctl = ac->in(0);
997 Node* src = ac->in(ArrayCopyNode::Src);
998
999 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1000 return NULL;
1001 }
1002
1003 LoadNode* ld = clone()->as_Load();
1004 Node* addp = in(MemNode::Address)->clone();
1005 if (ac->as_ArrayCopy()->is_clonebasic()) {
1006 assert(ld_alloc != NULL, "need an alloc");
1007 assert(addp->is_AddP(), "address must be addp");
1008 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1009 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1010 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1011 addp->set_req(AddPNode::Base, src);
1012 addp->set_req(AddPNode::Address, src);
1013 } else {
1014 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1015 ac->as_ArrayCopy()->is_copyof_validated() ||
1016 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1017 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1018 addp->set_req(AddPNode::Base, src);
1019 addp->set_req(AddPNode::Address, src);
1020
1021 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1022 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
1023 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1024 uint shift = exact_log2(type2aelembytes(ary_elem));
1025 if (ary_t->klass()->is_flat_array_klass()) {
1026 ciFlatArrayKlass* vak = ary_t->klass()->as_flat_array_klass();
1027 shift = vak->log2_element_size();
1028 }
1029
1030 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1031 #ifdef _LP64
1032 diff = phase->transform(new ConvI2LNode(diff));
1033 #endif
1034 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1035
1036 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1037 addp->set_req(AddPNode::Offset, offset);
1038 }
1039 addp = phase->transform(addp);
1040 #ifdef ASSERT
1041 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1042 ld->_adr_type = adr_type;
1043 #endif
1044 ld->set_req(MemNode::Address, addp);
1045 ld->set_req(0, ctl);
1046 ld->set_req(MemNode::Memory, mem);
1047 // load depends on the tests that validate the arraycopy
1048 ld->_control_dependency = UnknownControl;
1049 return ld;
1050 }
1051 return NULL;
1052 }
1053
1054
1055 //---------------------------can_see_stored_value------------------------------
1056 // This routine exists to make sure this set of tests is done the same
1057 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1058 // will change the graph shape in a way which makes memory alive twice at the
1059 // same time (uses the Oracle model of aliasing), then some
1060 // LoadXNode::Identity will fold things back to the equivalence-class model
1061 // of aliasing.
1062 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1063 Node* ld_adr = in(MemNode::Address);
1064 intptr_t ld_off = 0;
1065 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1066 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1067 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1068 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1069 // This is more general than load from boxing objects.
1070 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1071 uint alias_idx = atp->index();
1072 Node* result = NULL;
1073 Node* current = st;
1074 // Skip through chains of MemBarNodes checking the MergeMems for
1075 // new states for the slice of this load. Stop once any other
1076 // kind of node is encountered. Loads from final memory can skip
1077 // through any kind of MemBar but normal loads shouldn't skip
1078 // through MemBarAcquire since the could allow them to move out of
1079 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1080 // because alias info above them may be inaccurate (e.g., due to
1081 // mixed/mismatched unsafe accesses).
1082 bool is_final_mem = !atp->is_rewritable();
1083 while (current->is_Proj()) {
1084 int opc = current->in(0)->Opcode();
1085 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1086 opc == Op_MemBarAcquireLock ||
1087 opc == Op_LoadFence)) ||
1088 opc == Op_MemBarRelease ||
1089 opc == Op_StoreFence ||
1090 opc == Op_MemBarReleaseLock ||
1091 opc == Op_MemBarStoreStore ||
1092 opc == Op_StoreStoreFence) {
1093 Node* mem = current->in(0)->in(TypeFunc::Memory);
1094 if (mem->is_MergeMem()) {
1095 MergeMemNode* merge = mem->as_MergeMem();
1096 Node* new_st = merge->memory_at(alias_idx);
1097 if (new_st == merge->base_memory()) {
1098 // Keep searching
1099 current = new_st;
1100 continue;
1101 }
1102 // Save the new memory state for the slice and fall through
1103 // to exit.
1104 result = new_st;
1105 }
1106 }
1107 break;
1108 }
1109 if (result != NULL) {
1110 st = result;
1111 }
1112 }
1113
1114 // Loop around twice in the case Load -> Initialize -> Store.
1115 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1116 for (int trip = 0; trip <= 1; trip++) {
1117
1118 if (st->is_Store()) {
1119 Node* st_adr = st->in(MemNode::Address);
1120 if (st_adr != ld_adr) {
1121 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1122 intptr_t st_off = 0;
1123 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1124 if (ld_base == NULL) return NULL;
1125 if (st_base == NULL) return NULL;
1126 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL;
1127 if (ld_off != st_off) return NULL;
1128 if (ld_off == Type::OffsetBot) return NULL;
1129 // Same base, same offset.
1130 // Possible improvement for arrays: check index value instead of absolute offset.
1131
1132 // At this point we have proven something like this setup:
1133 // B = << base >>
1134 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1135 // S = StoreQ(AddP( B , #Off), V)
1136 // (Actually, we haven't yet proven the Q's are the same.)
1137 // In other words, we are loading from a casted version of
1138 // the same pointer-and-offset that we stored to.
1139 // Casted version may carry a dependency and it is respected.
1140 // Thus, we are able to replace L by V.
1141 }
1142 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1143 if (store_Opcode() != st->Opcode()) {
1144 return NULL;
1145 }
1146 // LoadVector/StoreVector needs additional check to ensure the types match.
1147 if (st->is_StoreVector()) {
1148 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1149 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1150 if (in_vt != out_vt) {
1151 return NULL;
1152 }
1153 }
1154 return st->in(MemNode::ValueIn);
1155 }
1156
1157 // A load from a freshly-created object always returns zero.
1158 // (This can happen after LoadNode::Ideal resets the load's memory input
1159 // to find_captured_store, which returned InitializeNode::zero_memory.)
1160 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1161 (st->in(0) == ld_alloc) &&
1162 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1163 // return a zero value for the load's basic type
1164 // (This is one of the few places where a generic PhaseTransform
1165 // can create new nodes. Think of it as lazily manifesting
1166 // virtually pre-existing constants.)
1167 assert(memory_type() != T_PRIMITIVE_OBJECT, "should not be used for inline types");
1168 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1169 if (default_value != NULL) {
1170 return default_value;
1171 }
1172 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null");
1173 if (memory_type() != T_VOID) {
1174 if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == NULL) {
1175 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1176 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1177 // by the ArrayCopyNode.
1178 return phase->zerocon(memory_type());
1179 }
1180 } else {
1181 // TODO: materialize all-zero vector constant
1182 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1183 }
1184 }
1185
1186 // A load from an initialization barrier can match a captured store.
1187 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1188 InitializeNode* init = st->in(0)->as_Initialize();
1189 AllocateNode* alloc = init->allocation();
1190 if ((alloc != NULL) && (alloc == ld_alloc)) {
1191 // examine a captured store value
1192 st = init->find_captured_store(ld_off, memory_size(), phase);
1193 if (st != NULL) {
1194 continue; // take one more trip around
1195 }
1196 }
1197 }
1198
1199 // Load boxed value from result of valueOf() call is input parameter.
1200 if (this->is_Load() && ld_adr->is_AddP() &&
1201 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1202 intptr_t ignore = 0;
1203 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1204 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1205 base = bs->step_over_gc_barrier(base);
1206 if (base != NULL && base->is_Proj() &&
1207 base->as_Proj()->_con == TypeFunc::Parms &&
1208 base->in(0)->is_CallStaticJava() &&
1209 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1210 return base->in(0)->in(TypeFunc::Parms);
1211 }
1212 }
1213
1214 break;
1215 }
1216
1217 return NULL;
1218 }
1219
1220 //----------------------is_instance_field_load_with_local_phi------------------
1221 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1222 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1223 in(Address)->is_AddP() ) {
1224 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1225 // Only instances and boxed values.
1226 if( t_oop != NULL &&
1227 (t_oop->is_ptr_to_boxed_value() ||
1228 t_oop->is_known_instance_field()) &&
1229 t_oop->offset() != Type::OffsetBot &&
1230 t_oop->offset() != Type::OffsetTop) {
1231 return true;
1232 }
1233 }
1234 return false;
1235 }
1236
1237 //------------------------------Identity---------------------------------------
1238 // Loads are identity if previous store is to same address
1239 Node* LoadNode::Identity(PhaseGVN* phase) {
1240 // Loading from an InlineTypePtr? The InlineTypePtr has the values of
1241 // all fields as input. Look for the field with matching offset.
1242 Node* addr = in(Address);
1243 intptr_t offset;
1244 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1245 if (base != NULL && base->is_InlineTypePtr() && offset > oopDesc::klass_offset_in_bytes()) {
1246 Node* value = base->as_InlineTypePtr()->field_value_by_offset((int)offset, true);
1247 if (value->is_InlineType()) {
1248 // Non-flattened inline type field
1249 InlineTypeNode* vt = value->as_InlineType();
1250 if (vt->is_allocated(phase)) {
1251 value = vt->get_oop();
1252 } else {
1253 // Not yet allocated, bail out
1254 value = NULL;
1255 }
1256 }
1257 if (value != NULL) {
1258 if (Opcode() == Op_LoadN) {
1259 // Encode oop value if we are loading a narrow oop
1260 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1261 value = phase->transform(new EncodePNode(value, bottom_type()));
1262 }
1263 return value;
1264 }
1265 }
1266
1267 // If the previous store-maker is the right kind of Store, and the store is
1268 // to the same address, then we are equal to the value stored.
1269 Node* mem = in(Memory);
1270 Node* value = can_see_stored_value(mem, phase);
1271 if( value ) {
1272 // byte, short & char stores truncate naturally.
1273 // A load has to load the truncated value which requires
1274 // some sort of masking operation and that requires an
1275 // Ideal call instead of an Identity call.
1276 if (memory_size() < BytesPerInt) {
1277 // If the input to the store does not fit with the load's result type,
1278 // it must be truncated via an Ideal call.
1279 if (!phase->type(value)->higher_equal(phase->type(this)))
1280 return this;
1281 }
1282 // (This works even when value is a Con, but LoadNode::Value
1283 // usually runs first, producing the singleton type of the Con.)
1284 return value;
1285 }
1286
1287 // Search for an existing data phi which was generated before for the same
1288 // instance's field to avoid infinite generation of phis in a loop.
1289 Node *region = mem->in(0);
1290 if (is_instance_field_load_with_local_phi(region)) {
1291 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1292 int this_index = phase->C->get_alias_index(addr_t);
1293 int this_offset = addr_t->offset();
1294 int this_iid = addr_t->instance_id();
1295 if (!addr_t->is_known_instance() &&
1296 addr_t->is_ptr_to_boxed_value()) {
1297 // Use _idx of address base (could be Phi node) for boxed values.
1298 intptr_t ignore = 0;
1299 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1300 if (base == NULL) {
1301 return this;
1302 }
1303 this_iid = base->_idx;
1304 }
1305 const Type* this_type = bottom_type();
1306 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1307 Node* phi = region->fast_out(i);
1308 if (phi->is_Phi() && phi != mem &&
1309 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1310 return phi;
1311 }
1312 }
1313 }
1314
1315 return this;
1316 }
1317
1318 // Construct an equivalent unsigned load.
1319 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1320 BasicType bt = T_ILLEGAL;
1321 const Type* rt = NULL;
1322 switch (Opcode()) {
1323 case Op_LoadUB: return this;
1324 case Op_LoadUS: return this;
1325 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1326 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1327 default:
1328 assert(false, "no unsigned variant: %s", Name());
1329 return NULL;
1330 }
1331 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1332 raw_adr_type(), rt, bt, _mo, _control_dependency,
1333 is_unaligned_access(), is_mismatched_access());
1334 }
1335
1336 // Construct an equivalent signed load.
1337 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1338 BasicType bt = T_ILLEGAL;
1339 const Type* rt = NULL;
1340 switch (Opcode()) {
1341 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1342 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1343 case Op_LoadB: // fall through
1344 case Op_LoadS: // fall through
1345 case Op_LoadI: // fall through
1346 case Op_LoadL: return this;
1347 default:
1348 assert(false, "no signed variant: %s", Name());
1349 return NULL;
1350 }
1351 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1352 raw_adr_type(), rt, bt, _mo, _control_dependency,
1353 is_unaligned_access(), is_mismatched_access());
1354 }
1355
1356 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1357 BasicType bt = rt->basic_type();
1358 switch (Opcode()) {
1359 case Op_LoadI: return (bt == T_FLOAT);
1360 case Op_LoadL: return (bt == T_DOUBLE);
1361 case Op_LoadF: return (bt == T_INT);
1362 case Op_LoadD: return (bt == T_LONG);
1363
1364 default: return false;
1365 }
1366 }
1367
1368 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1369 BasicType bt = rt->basic_type();
1370 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1371 bool is_mismatched = is_mismatched_access();
1372 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1373 if (raw_type == NULL) {
1374 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1375 }
1376 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1377 raw_adr_type(), rt, bt, _mo, _control_dependency,
1378 is_unaligned_access(), is_mismatched);
1379 }
1380
1381 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1382 BasicType bt = vt->basic_type();
1383 switch (Opcode()) {
1384 case Op_StoreI: return (bt == T_FLOAT);
1385 case Op_StoreL: return (bt == T_DOUBLE);
1386 case Op_StoreF: return (bt == T_INT);
1387 case Op_StoreD: return (bt == T_LONG);
1388
1389 default: return false;
1390 }
1391 }
1392
1393 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1394 BasicType bt = vt->basic_type();
1395 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1396 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address), raw_adr_type(), val, bt, _mo);
1397
1398 bool is_mismatched = is_mismatched_access();
1399 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1400 if (raw_type == NULL) {
1401 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1402 }
1403 if (is_mismatched) {
1404 st->set_mismatched_access();
1405 }
1406 return st;
1407 }
1408
1409 // We're loading from an object which has autobox behaviour.
1410 // If this object is result of a valueOf call we'll have a phi
1411 // merging a newly allocated object and a load from the cache.
1412 // We want to replace this load with the original incoming
1413 // argument to the valueOf call.
1414 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1415 assert(igvn->C->eliminate_boxing(), "sanity");
1416 intptr_t ignore = 0;
1417 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1418 if ((base == NULL) || base->is_Phi()) {
1419 // Push the loads from the phi that comes from valueOf up
1420 // through it to allow elimination of the loads and the recovery
1421 // of the original value. It is done in split_through_phi().
1422 return NULL;
1423 } else if (base->is_Load() ||
1424 (base->is_DecodeN() && base->in(1)->is_Load())) {
1425 // Eliminate the load of boxed value for integer types from the cache
1426 // array by deriving the value from the index into the array.
1427 // Capture the offset of the load and then reverse the computation.
1428
1429 // Get LoadN node which loads a boxing object from 'cache' array.
1430 if (base->is_DecodeN()) {
1431 base = base->in(1);
1432 }
1433 if (!base->in(Address)->is_AddP()) {
1434 return NULL; // Complex address
1435 }
1436 AddPNode* address = base->in(Address)->as_AddP();
1437 Node* cache_base = address->in(AddPNode::Base);
1438 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1439 // Get ConP node which is static 'cache' field.
1440 cache_base = cache_base->in(1);
1441 }
1442 if ((cache_base != NULL) && cache_base->is_Con()) {
1443 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1444 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1445 Node* elements[4];
1446 int shift = exact_log2(type2aelembytes(T_OBJECT));
1447 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1448 if (count > 0 && elements[0]->is_Con() &&
1449 (count == 1 ||
1450 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1451 elements[1]->in(2) == igvn->intcon(shift)))) {
1452 ciObjArray* array = base_type->const_oop()->as_obj_array();
1453 // Fetch the box object cache[0] at the base of the array and get its value
1454 ciInstance* box = array->obj_at(0)->as_instance();
1455 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1456 assert(ik->is_box_klass(), "sanity");
1457 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1458 if (ik->nof_nonstatic_fields() == 1) {
1459 // This should be true nonstatic_field_at requires calling
1460 // nof_nonstatic_fields so check it anyway
1461 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1462 BasicType bt = c.basic_type();
1463 // Only integer types have boxing cache.
1464 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1465 bt == T_BYTE || bt == T_SHORT ||
1466 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1467 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1468 if (cache_low != (int)cache_low) {
1469 return NULL; // should not happen since cache is array indexed by value
1470 }
1471 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1472 if (offset != (int)offset) {
1473 return NULL; // should not happen since cache is array indexed by value
1474 }
1475 // Add up all the offsets making of the address of the load
1476 Node* result = elements[0];
1477 for (int i = 1; i < count; i++) {
1478 result = igvn->transform(new AddXNode(result, elements[i]));
1479 }
1480 // Remove the constant offset from the address and then
1481 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1482 // remove the scaling of the offset to recover the original index.
1483 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1484 // Peel the shift off directly but wrap it in a dummy node
1485 // since Ideal can't return existing nodes
1486 igvn->_worklist.push(result); // remove dead node later
1487 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1488 } else if (result->is_Add() && result->in(2)->is_Con() &&
1489 result->in(1)->Opcode() == Op_LShiftX &&
1490 result->in(1)->in(2) == igvn->intcon(shift)) {
1491 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1492 // but for boxing cache access we know that X<<Z will not overflow
1493 // (there is range check) so we do this optimizatrion by hand here.
1494 igvn->_worklist.push(result); // remove dead node later
1495 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1496 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1497 } else {
1498 result = new RShiftXNode(result, igvn->intcon(shift));
1499 }
1500 #ifdef _LP64
1501 if (bt != T_LONG) {
1502 result = new ConvL2INode(igvn->transform(result));
1503 }
1504 #else
1505 if (bt == T_LONG) {
1506 result = new ConvI2LNode(igvn->transform(result));
1507 }
1508 #endif
1509 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1510 // Need to preserve unboxing load type if it is unsigned.
1511 switch(this->Opcode()) {
1512 case Op_LoadUB:
1513 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1514 break;
1515 case Op_LoadUS:
1516 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1517 break;
1518 }
1519 return result;
1520 }
1521 }
1522 }
1523 }
1524 }
1525 return NULL;
1526 }
1527
1528 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1529 Node* region = phi->in(0);
1530 if (region == NULL) {
1531 return false; // Wait stable graph
1532 }
1533 uint cnt = phi->req();
1534 for (uint i = 1; i < cnt; i++) {
1535 Node* rc = region->in(i);
1536 if (rc == NULL || phase->type(rc) == Type::TOP)
1537 return false; // Wait stable graph
1538 Node* in = phi->in(i);
1539 if (in == NULL || phase->type(in) == Type::TOP)
1540 return false; // Wait stable graph
1541 }
1542 return true;
1543 }
1544 //------------------------------split_through_phi------------------------------
1545 // Split instance or boxed field load through Phi.
1546 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1547 Node* mem = in(Memory);
1548 Node* address = in(Address);
1549 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1550
1551 assert((t_oop != NULL) &&
1552 (t_oop->is_known_instance_field() ||
1553 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1554
1555 Compile* C = phase->C;
1556 intptr_t ignore = 0;
1557 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1558 bool base_is_phi = (base != NULL) && base->is_Phi();
1559 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1560 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1561 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1562
1563 if (!((mem->is_Phi() || base_is_phi) &&
1564 (load_boxed_values || t_oop->is_known_instance_field()))) {
1565 return NULL; // memory is not Phi
1566 }
1567
1568 if (mem->is_Phi()) {
1569 if (!stable_phi(mem->as_Phi(), phase)) {
1570 return NULL; // Wait stable graph
1571 }
1572 uint cnt = mem->req();
1573 // Check for loop invariant memory.
1574 if (cnt == 3) {
1575 for (uint i = 1; i < cnt; i++) {
1576 Node* in = mem->in(i);
1577 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1578 if (m == mem) {
1579 if (i == 1) {
1580 // if the first edge was a loop, check second edge too.
1581 // If both are replaceable - we are in an infinite loop
1582 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1583 if (n == mem) {
1584 break;
1585 }
1586 }
1587 set_req(Memory, mem->in(cnt - i));
1588 return this; // made change
1589 }
1590 }
1591 }
1592 }
1593 if (base_is_phi) {
1594 if (!stable_phi(base->as_Phi(), phase)) {
1595 return NULL; // Wait stable graph
1596 }
1597 uint cnt = base->req();
1598 // Check for loop invariant memory.
1599 if (cnt == 3) {
1600 for (uint i = 1; i < cnt; i++) {
1601 if (base->in(i) == base) {
1602 return NULL; // Wait stable graph
1603 }
1604 }
1605 }
1606 }
1607
1608 // Split through Phi (see original code in loopopts.cpp).
1609 assert(C->have_alias_type(t_oop), "instance should have alias type");
1610
1611 // Do nothing here if Identity will find a value
1612 // (to avoid infinite chain of value phis generation).
1613 if (this != Identity(phase)) {
1614 return NULL;
1615 }
1616
1617 // Select Region to split through.
1618 Node* region;
1619 if (!base_is_phi) {
1620 assert(mem->is_Phi(), "sanity");
1621 region = mem->in(0);
1622 // Skip if the region dominates some control edge of the address.
1623 if (!MemNode::all_controls_dominate(address, region))
1624 return NULL;
1625 } else if (!mem->is_Phi()) {
1626 assert(base_is_phi, "sanity");
1627 region = base->in(0);
1628 // Skip if the region dominates some control edge of the memory.
1629 if (!MemNode::all_controls_dominate(mem, region))
1630 return NULL;
1631 } else if (base->in(0) != mem->in(0)) {
1632 assert(base_is_phi && mem->is_Phi(), "sanity");
1633 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1634 region = base->in(0);
1635 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1636 region = mem->in(0);
1637 } else {
1638 return NULL; // complex graph
1639 }
1640 } else {
1641 assert(base->in(0) == mem->in(0), "sanity");
1642 region = mem->in(0);
1643 }
1644
1645 const Type* this_type = this->bottom_type();
1646 int this_index = C->get_alias_index(t_oop);
1647 int this_offset = t_oop->offset();
1648 int this_iid = t_oop->instance_id();
1649 if (!t_oop->is_known_instance() && load_boxed_values) {
1650 // Use _idx of address base for boxed values.
1651 this_iid = base->_idx;
1652 }
1653 PhaseIterGVN* igvn = phase->is_IterGVN();
1654 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1655 for (uint i = 1; i < region->req(); i++) {
1656 Node* x;
1657 Node* the_clone = NULL;
1658 Node* in = region->in(i);
1659 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1660 in != NULL && in->is_OuterStripMinedLoop()) {
1661 // No node should go in the outer strip mined loop
1662 in = in->in(LoopNode::EntryControl);
1663 }
1664 if (in == NULL || in == C->top()) {
1665 x = C->top(); // Dead path? Use a dead data op
1666 } else {
1667 x = this->clone(); // Else clone up the data op
1668 the_clone = x; // Remember for possible deletion.
1669 // Alter data node to use pre-phi inputs
1670 if (this->in(0) == region) {
1671 x->set_req(0, in);
1672 } else {
1673 x->set_req(0, NULL);
1674 }
1675 if (mem->is_Phi() && (mem->in(0) == region)) {
1676 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1677 }
1678 if (address->is_Phi() && address->in(0) == region) {
1679 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1680 }
1681 if (base_is_phi && (base->in(0) == region)) {
1682 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1683 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1684 x->set_req(Address, adr_x);
1685 }
1686 }
1687 // Check for a 'win' on some paths
1688 const Type *t = x->Value(igvn);
1689
1690 bool singleton = t->singleton();
1691
1692 // See comments in PhaseIdealLoop::split_thru_phi().
1693 if (singleton && t == Type::TOP) {
1694 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1695 }
1696
1697 if (singleton) {
1698 x = igvn->makecon(t);
1699 } else {
1700 // We now call Identity to try to simplify the cloned node.
1701 // Note that some Identity methods call phase->type(this).
1702 // Make sure that the type array is big enough for
1703 // our new node, even though we may throw the node away.
1704 // (This tweaking with igvn only works because x is a new node.)
1705 igvn->set_type(x, t);
1706 // If x is a TypeNode, capture any more-precise type permanently into Node
1707 // otherwise it will be not updated during igvn->transform since
1708 // igvn->type(x) is set to x->Value() already.
1709 x->raise_bottom_type(t);
1710 Node* y = x->Identity(igvn);
1711 if (y != x) {
1712 x = y;
1713 } else {
1714 y = igvn->hash_find_insert(x);
1715 if (y) {
1716 x = y;
1717 } else {
1718 // Else x is a new node we are keeping
1719 // We do not need register_new_node_with_optimizer
1720 // because set_type has already been called.
1721 igvn->_worklist.push(x);
1722 }
1723 }
1724 }
1725 if (x != the_clone && the_clone != NULL) {
1726 igvn->remove_dead_node(the_clone);
1727 }
1728 phi->set_req(i, x);
1729 }
1730 // Record Phi
1731 igvn->register_new_node_with_optimizer(phi);
1732 return phi;
1733 }
1734
1735 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1736 if (Opcode() == Op_LoadX) {
1737 Node* address = in(MemNode::Address);
1738 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1739 Node* mem = in(MemNode::Memory);
1740 if (alloc != NULL && mem->is_Proj() &&
1741 mem->in(0) != NULL &&
1742 mem->in(0) == alloc->initialization() &&
1743 alloc->initialization()->proj_out_or_null(0) != NULL) {
1744 return alloc;
1745 }
1746 }
1747 return NULL;
1748 }
1749
1750
1751 //------------------------------Ideal------------------------------------------
1752 // If the load is from Field memory and the pointer is non-null, it might be possible to
1753 // zero out the control input.
1754 // If the offset is constant and the base is an object allocation,
1755 // try to hook me up to the exact initializing store.
1756 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1757 Node* p = MemNode::Ideal_common(phase, can_reshape);
1758 if (p) return (p == NodeSentinel) ? NULL : p;
1759
1760 Node* ctrl = in(MemNode::Control);
1761 Node* address = in(MemNode::Address);
1762 bool progress = false;
1763
1764 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1765 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1766
1767 // Skip up past a SafePoint control. Cannot do this for Stores because
1768 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1769 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1770 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1771 !addr_mark &&
1772 (depends_only_on_test() || has_unknown_control_dependency())) {
1773 ctrl = ctrl->in(0);
1774 set_req(MemNode::Control,ctrl);
1775 progress = true;
1776 }
1777
1778 intptr_t ignore = 0;
1779 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1780 if (base != NULL
1781 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1782 // Check for useless control edge in some common special cases
1783 if (in(MemNode::Control) != NULL
1784 && can_remove_control()
1785 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1786 && all_controls_dominate(base, phase->C->start())) {
1787 // A method-invariant, non-null address (constant or 'this' argument).
1788 set_req(MemNode::Control, NULL);
1789 progress = true;
1790 }
1791 }
1792
1793 Node* mem = in(MemNode::Memory);
1794 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1795
1796 if (can_reshape && (addr_t != NULL)) {
1797 // try to optimize our memory input
1798 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1799 if (opt_mem != mem) {
1800 set_req_X(MemNode::Memory, opt_mem, phase);
1801 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1802 return this;
1803 }
1804 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1805 if ((t_oop != NULL) &&
1806 (t_oop->is_known_instance_field() ||
1807 t_oop->is_ptr_to_boxed_value())) {
1808 PhaseIterGVN *igvn = phase->is_IterGVN();
1809 assert(igvn != NULL, "must be PhaseIterGVN when can_reshape is true");
1810 if (igvn->_worklist.member(opt_mem)) {
1811 // Delay this transformation until memory Phi is processed.
1812 igvn->_worklist.push(this);
1813 return NULL;
1814 }
1815 // Split instance field load through Phi.
1816 Node* result = split_through_phi(phase);
1817 if (result != NULL) return result;
1818
1819 if (t_oop->is_ptr_to_boxed_value()) {
1820 Node* result = eliminate_autobox(igvn);
1821 if (result != NULL) return result;
1822 }
1823 }
1824 }
1825
1826 // Is there a dominating load that loads the same value? Leave
1827 // anything that is not a load of a field/array element (like
1828 // barriers etc.) alone
1829 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1830 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1831 Node *use = mem->fast_out(i);
1832 if (use != this &&
1833 use->Opcode() == Opcode() &&
1834 use->in(0) != NULL &&
1835 use->in(0) != in(0) &&
1836 use->in(Address) == in(Address)) {
1837 Node* ctl = in(0);
1838 for (int i = 0; i < 10 && ctl != NULL; i++) {
1839 ctl = IfNode::up_one_dom(ctl);
1840 if (ctl == use->in(0)) {
1841 set_req(0, use->in(0));
1842 return this;
1843 }
1844 }
1845 }
1846 }
1847 }
1848
1849 // Check for prior store with a different base or offset; make Load
1850 // independent. Skip through any number of them. Bail out if the stores
1851 // are in an endless dead cycle and report no progress. This is a key
1852 // transform for Reflection. However, if after skipping through the Stores
1853 // we can't then fold up against a prior store do NOT do the transform as
1854 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1855 // array memory alive twice: once for the hoisted Load and again after the
1856 // bypassed Store. This situation only works if EVERYBODY who does
1857 // anti-dependence work knows how to bypass. I.e. we need all
1858 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1859 // the alias index stuff. So instead, peek through Stores and IFF we can
1860 // fold up, do so.
1861 Node* prev_mem = find_previous_store(phase);
1862 if (prev_mem != NULL) {
1863 Node* value = can_see_arraycopy_value(prev_mem, phase);
1864 if (value != NULL) {
1865 return value;
1866 }
1867 }
1868 // Steps (a), (b): Walk past independent stores to find an exact match.
1869 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1870 // (c) See if we can fold up on the spot, but don't fold up here.
1871 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1872 // just return a prior value, which is done by Identity calls.
1873 if (can_see_stored_value(prev_mem, phase)) {
1874 // Make ready for step (d):
1875 set_req_X(MemNode::Memory, prev_mem, phase);
1876 return this;
1877 }
1878 }
1879
1880 return progress ? this : NULL;
1881 }
1882
1883 // Helper to recognize certain Klass fields which are invariant across
1884 // some group of array types (e.g., int[] or all T[] where T < Object).
1885 const Type*
1886 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1887 ciKlass* klass) const {
1888 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1889 // The field is Klass::_modifier_flags. Return its (constant) value.
1890 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1891 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1892 return TypeInt::make(klass->modifier_flags());
1893 }
1894 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1895 // The field is Klass::_access_flags. Return its (constant) value.
1896 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1897 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1898 return TypeInt::make(klass->access_flags());
1899 }
1900 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1901 // The field is Klass::_layout_helper. Return its constant value if known.
1902 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1903 return TypeInt::make(klass->layout_helper());
1904 }
1905
1906 // No match.
1907 return NULL;
1908 }
1909
1910 //------------------------------Value-----------------------------------------
1911 const Type* LoadNode::Value(PhaseGVN* phase) const {
1912 // Either input is TOP ==> the result is TOP
1913 Node* mem = in(MemNode::Memory);
1914 const Type *t1 = phase->type(mem);
1915 if (t1 == Type::TOP) return Type::TOP;
1916 Node* adr = in(MemNode::Address);
1917 const TypePtr* tp = phase->type(adr)->isa_ptr();
1918 if (tp == NULL || tp->empty()) return Type::TOP;
1919 int off = tp->offset();
1920 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1921 Compile* C = phase->C;
1922
1923 // Try to guess loaded type from pointer type
1924 if (tp->isa_aryptr()) {
1925 const TypeAryPtr* ary = tp->is_aryptr();
1926 const Type* t = ary->elem();
1927
1928 // Determine whether the reference is beyond the header or not, by comparing
1929 // the offset against the offset of the start of the array's data.
1930 // Different array types begin at slightly different offsets (12 vs. 16).
1931 // We choose T_BYTE as an example base type that is least restrictive
1932 // as to alignment, which will therefore produce the smallest
1933 // possible base offset.
1934 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1935 const bool off_beyond_header = (off >= min_base_off);
1936
1937 // Try to constant-fold a stable array element.
1938 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1939 // Make sure the reference is not into the header and the offset is constant
1940 ciObject* aobj = ary->const_oop();
1941 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1942 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1943 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1944 stable_dimension,
1945 memory_type(), is_unsigned());
1946 if (con_type != NULL) {
1947 return con_type;
1948 }
1949 }
1950 }
1951
1952 // Don't do this for integer types. There is only potential profit if
1953 // the element type t is lower than _type; that is, for int types, if _type is
1954 // more restrictive than t. This only happens here if one is short and the other
1955 // char (both 16 bits), and in those cases we've made an intentional decision
1956 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1957 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1958 //
1959 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1960 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1961 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1962 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1963 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1964 // In fact, that could have been the original type of p1, and p1 could have
1965 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1966 // expression (LShiftL quux 3) independently optimized to the constant 8.
1967 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1968 && (_type->isa_vect() == NULL)
1969 && t->isa_inlinetype() == NULL
1970 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1971 // t might actually be lower than _type, if _type is a unique
1972 // concrete subclass of abstract class t.
1973 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1974 const Type* jt = t->join_speculative(_type);
1975 // In any case, do not allow the join, per se, to empty out the type.
1976 if (jt->empty() && !t->empty()) {
1977 // This can happen if a interface-typed array narrows to a class type.
1978 jt = _type;
1979 }
1980 #ifdef ASSERT
1981 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1982 // The pointers in the autobox arrays are always non-null
1983 Node* base = adr->in(AddPNode::Base);
1984 if ((base != NULL) && base->is_DecodeN()) {
1985 // Get LoadN node which loads IntegerCache.cache field
1986 base = base->in(1);
1987 }
1988 if ((base != NULL) && base->is_Con()) {
1989 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1990 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1991 // It could be narrow oop
1992 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1993 }
1994 }
1995 }
1996 #endif
1997 return jt;
1998 }
1999 }
2000 } else if (tp->base() == Type::InstPtr) {
2001 assert( off != Type::OffsetBot ||
2002 // arrays can be cast to Objects
2003 tp->is_oopptr()->klass()->is_java_lang_Object() ||
2004 tp->is_oopptr()->klass() == ciEnv::current()->Class_klass() ||
2005 // unsafe field access may not have a constant offset
2006 C->has_unsafe_access(),
2007 "Field accesses must be precise" );
2008 // For oop loads, we expect the _type to be precise.
2009
2010 const TypeInstPtr* tinst = tp->is_instptr();
2011 BasicType bt = memory_type();
2012
2013 // Optimize loads from constant fields.
2014 ciObject* const_oop = tinst->const_oop();
2015 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
2016 ciType* mirror_type = const_oop->as_instance()->java_mirror_type();
2017 if (mirror_type != NULL) {
2018 const Type* const_oop = NULL;
2019 ciInlineKlass* vk = mirror_type->is_inlinetype() ? mirror_type->as_inline_klass() : NULL;
2020 // Fold default value loads
2021 if (vk != NULL && off == vk->default_value_offset()) {
2022 const_oop = TypeInstPtr::make(vk->default_instance());
2023 }
2024 // Fold class mirror loads
2025 if (off == java_lang_Class::primary_mirror_offset()) {
2026 const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->ref_instance());
2027 } else if (off == java_lang_Class::secondary_mirror_offset()) {
2028 const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->val_instance());
2029 }
2030 if (const_oop != NULL) {
2031 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
2032 }
2033 }
2034 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2035 if (con_type != NULL) {
2036 return con_type;
2037 }
2038 }
2039 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2040 assert( off != Type::OffsetBot ||
2041 // arrays can be cast to Objects
2042 tp->is_klassptr()->klass() == NULL ||
2043 tp->is_klassptr()->klass()->is_java_lang_Object() ||
2044 // also allow array-loading from the primary supertype
2045 // array during subtype checks
2046 Opcode() == Op_LoadKlass,
2047 "Field accesses must be precise" );
2048 // For klass/static loads, we expect the _type to be precise
2049 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
2050 if (adr->is_Load() && off == 0) {
2051 /* With mirrors being an indirect in the Klass*
2052 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2053 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2054 *
2055 * So check the type and klass of the node before the LoadP.
2056 */
2057 Node* adr2 = adr->in(MemNode::Address);
2058 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2059 if (tkls != NULL) {
2060 ciKlass* klass = tkls->klass();
2061 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2062 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2063 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2064 return TypeInstPtr::make(klass->java_mirror());
2065 }
2066 }
2067 } else {
2068 // Check for a load of the default value offset from the InlineKlassFixedBlock:
2069 // LoadI(LoadP(inline_klass, adr_inlineklass_fixed_block_offset), default_value_offset_offset)
2070 intptr_t offset = 0;
2071 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2072 if (base != NULL && base->is_Load() && offset == in_bytes(InlineKlass::default_value_offset_offset())) {
2073 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
2074 if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->isa_inlinetype() &&
2075 tkls->offset() == in_bytes(InstanceKlass::adr_inlineklass_fixed_block_offset())) {
2076 assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
2077 assert(Opcode() == Op_LoadI, "must load an int from fixed block");
2078 return TypeInt::make(tkls->klass()->as_inline_klass()->default_value_offset());
2079 }
2080 }
2081 }
2082 }
2083
2084 const TypeKlassPtr *tkls = tp->isa_klassptr();
2085 if (tkls != NULL && !StressReflectiveCode) {
2086 ciKlass* klass = tkls->klass();
2087 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2088 // We are loading a field from a Klass metaobject whose identity
2089 // is known at compile time (the type is "exact" or "precise").
2090 // Check for fields we know are maintained as constants by the VM.
2091 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2092 // The field is Klass::_super_check_offset. Return its (constant) value.
2093 // (Folds up type checking code.)
2094 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2095 return TypeInt::make(klass->super_check_offset());
2096 }
2097 // Compute index into primary_supers array
2098 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2099 // Check for overflowing; use unsigned compare to handle the negative case.
2100 if( depth < ciKlass::primary_super_limit() ) {
2101 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2102 // (Folds up type checking code.)
2103 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2104 ciKlass *ss = klass->super_of_depth(depth);
2105 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2106 }
2107 const Type* aift = load_array_final_field(tkls, klass);
2108 if (aift != NULL) return aift;
2109 }
2110
2111 // We can still check if we are loading from the primary_supers array at a
2112 // shallow enough depth. Even though the klass is not exact, entries less
2113 // than or equal to its super depth are correct.
2114 if (tkls->is_loaded()) {
2115 ciType *inner = klass;
2116 while( inner->is_obj_array_klass() )
2117 inner = inner->as_obj_array_klass()->base_element_type();
2118 if( inner->is_instance_klass() &&
2119 !inner->as_instance_klass()->flags().is_interface() ) {
2120 // Compute index into primary_supers array
2121 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2122 // Check for overflowing; use unsigned compare to handle the negative case.
2123 if( depth < ciKlass::primary_super_limit() &&
2124 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
2125 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2126 // (Folds up type checking code.)
2127 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2128 ciKlass *ss = klass->super_of_depth(depth);
2129 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
2130 }
2131 }
2132 }
2133
2134 // If the type is enough to determine that the thing is not an array,
2135 // we can give the layout_helper a positive interval type.
2136 // This will help short-circuit some reflective code.
2137 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
2138 && !klass->is_array_klass() // not directly typed as an array
2139 && !klass->is_interface() // specifically not Serializable & Cloneable
2140 && !klass->is_java_lang_Object() // not the supertype of all T[]
2141 ) {
2142 // Note: When interfaces are reliable, we can narrow the interface
2143 // test to (klass != Serializable && klass != Cloneable).
2144 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2145 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2146 // The key property of this type is that it folds up tests
2147 // for array-ness, since it proves that the layout_helper is positive.
2148 // Thus, a generic value like the basic object layout helper works fine.
2149 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2150 }
2151 }
2152
2153 // If we are loading from a freshly-allocated object, produce a zero,
2154 // if the load is provably beyond the header of the object.
2155 // (Also allow a variable load from a fresh array to produce zero.)
2156 const TypeOopPtr *tinst = tp->isa_oopptr();
2157 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
2158 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
2159 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2160 Node* value = can_see_stored_value(mem,phase);
2161 if (value != NULL && value->is_Con()) {
2162 assert(value->bottom_type()->higher_equal(_type),"sanity");
2163 return value->bottom_type();
2164 }
2165 }
2166
2167 bool is_vect = (_type->isa_vect() != NULL);
2168 if (is_instance && !is_vect) {
2169 // If we have an instance type and our memory input is the
2170 // programs's initial memory state, there is no matching store,
2171 // so just return a zero of the appropriate type -
2172 // except if it is vectorized - then we have no zero constant.
2173 Node *mem = in(MemNode::Memory);
2174 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2175 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2176 return Type::get_zero_type(_type->basic_type());
2177 }
2178 }
2179 Node* alloc = is_new_object_mark_load(phase);
2180 if (alloc != NULL) {
2181 if (EnableValhalla) {
2182 // The mark word may contain property bits (inline, flat, null-free)
2183 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2184 const TypeKlassPtr* tkls = phase->type(klass_node)->is_klassptr();
2185 ciKlass* klass = tkls->klass();
2186 if (klass != NULL && klass->is_loaded() && tkls->klass_is_exact()) {
2187 return TypeX::make(klass->prototype_header().value());
2188 }
2189 } else {
2190 return TypeX::make(markWord::prototype().value());
2191 }
2192 }
2193
2194 return _type;
2195 }
2196
2197 //------------------------------match_edge-------------------------------------
2198 // Do we Match on this edge index or not? Match only the address.
2199 uint LoadNode::match_edge(uint idx) const {
2200 return idx == MemNode::Address;
2201 }
2202
2203 //--------------------------LoadBNode::Ideal--------------------------------------
2204 //
2205 // If the previous store is to the same address as this load,
2206 // and the value stored was larger than a byte, replace this load
2207 // with the value stored truncated to a byte. If no truncation is
2208 // needed, the replacement is done in LoadNode::Identity().
2209 //
2210 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2211 Node* mem = in(MemNode::Memory);
2212 Node* value = can_see_stored_value(mem,phase);
2213 if (value != NULL) {
2214 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2215 if (narrow != value) {
2216 return narrow;
2217 }
2218 }
2219 // Identity call will handle the case where truncation is not needed.
2220 return LoadNode::Ideal(phase, can_reshape);
2221 }
2222
2223 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2224 Node* mem = in(MemNode::Memory);
2225 Node* value = can_see_stored_value(mem,phase);
2226 if (value != NULL && value->is_Con() &&
2227 !value->bottom_type()->higher_equal(_type)) {
2228 // If the input to the store does not fit with the load's result type,
2229 // it must be truncated. We can't delay until Ideal call since
2230 // a singleton Value is needed for split_thru_phi optimization.
2231 int con = value->get_int();
2232 return TypeInt::make((con << 24) >> 24);
2233 }
2234 return LoadNode::Value(phase);
2235 }
2236
2237 //--------------------------LoadUBNode::Ideal-------------------------------------
2238 //
2239 // If the previous store is to the same address as this load,
2240 // and the value stored was larger than a byte, replace this load
2241 // with the value stored truncated to a byte. If no truncation is
2242 // needed, the replacement is done in LoadNode::Identity().
2243 //
2244 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2245 Node* mem = in(MemNode::Memory);
2246 Node* value = can_see_stored_value(mem, phase);
2247 if (value != NULL) {
2248 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2249 if (narrow != value) {
2250 return narrow;
2251 }
2252 }
2253 // Identity call will handle the case where truncation is not needed.
2254 return LoadNode::Ideal(phase, can_reshape);
2255 }
2256
2257 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2258 Node* mem = in(MemNode::Memory);
2259 Node* value = can_see_stored_value(mem,phase);
2260 if (value != NULL && value->is_Con() &&
2261 !value->bottom_type()->higher_equal(_type)) {
2262 // If the input to the store does not fit with the load's result type,
2263 // it must be truncated. We can't delay until Ideal call since
2264 // a singleton Value is needed for split_thru_phi optimization.
2265 int con = value->get_int();
2266 return TypeInt::make(con & 0xFF);
2267 }
2268 return LoadNode::Value(phase);
2269 }
2270
2271 //--------------------------LoadUSNode::Ideal-------------------------------------
2272 //
2273 // If the previous store is to the same address as this load,
2274 // and the value stored was larger than a char, replace this load
2275 // with the value stored truncated to a char. If no truncation is
2276 // needed, the replacement is done in LoadNode::Identity().
2277 //
2278 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2279 Node* mem = in(MemNode::Memory);
2280 Node* value = can_see_stored_value(mem,phase);
2281 if (value != NULL) {
2282 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2283 if (narrow != value) {
2284 return narrow;
2285 }
2286 }
2287 // Identity call will handle the case where truncation is not needed.
2288 return LoadNode::Ideal(phase, can_reshape);
2289 }
2290
2291 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2292 Node* mem = in(MemNode::Memory);
2293 Node* value = can_see_stored_value(mem,phase);
2294 if (value != NULL && value->is_Con() &&
2295 !value->bottom_type()->higher_equal(_type)) {
2296 // If the input to the store does not fit with the load's result type,
2297 // it must be truncated. We can't delay until Ideal call since
2298 // a singleton Value is needed for split_thru_phi optimization.
2299 int con = value->get_int();
2300 return TypeInt::make(con & 0xFFFF);
2301 }
2302 return LoadNode::Value(phase);
2303 }
2304
2305 //--------------------------LoadSNode::Ideal--------------------------------------
2306 //
2307 // If the previous store is to the same address as this load,
2308 // and the value stored was larger than a short, replace this load
2309 // with the value stored truncated to a short. If no truncation is
2310 // needed, the replacement is done in LoadNode::Identity().
2311 //
2312 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2313 Node* mem = in(MemNode::Memory);
2314 Node* value = can_see_stored_value(mem,phase);
2315 if (value != NULL) {
2316 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2317 if (narrow != value) {
2318 return narrow;
2319 }
2320 }
2321 // Identity call will handle the case where truncation is not needed.
2322 return LoadNode::Ideal(phase, can_reshape);
2323 }
2324
2325 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2326 Node* mem = in(MemNode::Memory);
2327 Node* value = can_see_stored_value(mem,phase);
2328 if (value != NULL && value->is_Con() &&
2329 !value->bottom_type()->higher_equal(_type)) {
2330 // If the input to the store does not fit with the load's result type,
2331 // it must be truncated. We can't delay until Ideal call since
2332 // a singleton Value is needed for split_thru_phi optimization.
2333 int con = value->get_int();
2334 return TypeInt::make((con << 16) >> 16);
2335 }
2336 return LoadNode::Value(phase);
2337 }
2338
2339 //=============================================================================
2340 //----------------------------LoadKlassNode::make------------------------------
2341 // Polymorphic factory method:
2342 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
2343 const TypeKlassPtr* tk) {
2344 // sanity check the alias category against the created node type
2345 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2346 assert(adr_type != NULL, "expecting TypeKlassPtr");
2347 #ifdef _LP64
2348 if (adr_type->is_ptr_to_narrowklass()) {
2349 assert(UseCompressedClassPointers, "no compressed klasses");
2350 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2351 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2352 }
2353 #endif
2354 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2355 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2356 }
2357
2358 //------------------------------Value------------------------------------------
2359 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2360 return klass_value_common(phase);
2361 }
2362
2363 // In most cases, LoadKlassNode does not have the control input set. If the control
2364 // input is set, it must not be removed (by LoadNode::Ideal()).
2365 bool LoadKlassNode::can_remove_control() const {
2366 return false;
2367 }
2368
2369 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2370 // Either input is TOP ==> the result is TOP
2371 const Type *t1 = phase->type( in(MemNode::Memory) );
2372 if (t1 == Type::TOP) return Type::TOP;
2373 Node *adr = in(MemNode::Address);
2374 const Type *t2 = phase->type( adr );
2375 if (t2 == Type::TOP) return Type::TOP;
2376 const TypePtr *tp = t2->is_ptr();
2377 if (TypePtr::above_centerline(tp->ptr()) ||
2378 tp->ptr() == TypePtr::Null) return Type::TOP;
2379
2380 // Return a more precise klass, if possible
2381 const TypeInstPtr *tinst = tp->isa_instptr();
2382 if (tinst != NULL) {
2383 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2384 int offset = tinst->offset();
2385 if (ik == phase->C->env()->Class_klass()
2386 && (offset == java_lang_Class::klass_offset() ||
2387 offset == java_lang_Class::array_klass_offset())) {
2388 // We are loading a special hidden field from a Class mirror object,
2389 // the field which points to the VM's Klass metaobject.
2390 bool null_free = false;
2391 ciType* t = tinst->java_mirror_type(&null_free);
2392 // java_mirror_type returns non-null for compile-time Class constants.
2393 if (t != NULL) {
2394 // constant oop => constant klass
2395 if (offset == java_lang_Class::array_klass_offset()) {
2396 if (t->is_void()) {
2397 // We cannot create a void array. Since void is a primitive type return null
2398 // klass. Users of this result need to do a null check on the returned klass.
2399 return TypePtr::NULL_PTR;
2400 }
2401 return TypeKlassPtr::make(ciArrayKlass::make(t, null_free));
2402 }
2403 if (!t->is_klass()) {
2404 // a primitive Class (e.g., int.class) has NULL for a klass field
2405 return TypePtr::NULL_PTR;
2406 }
2407 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2408 return TypeKlassPtr::make(t->as_klass());
2409 }
2410 // non-constant mirror, so we can't tell what's going on
2411 }
2412 if( !ik->is_loaded() )
2413 return _type; // Bail out if not loaded
2414 if (offset == oopDesc::klass_offset_in_bytes()) {
2415 if (tinst->klass_is_exact()) {
2416 return TypeKlassPtr::make(ik);
2417 }
2418 // See if we can become precise: no subklasses and no interface
2419 // (Note: We need to support verified interfaces.)
2420 if (!ik->is_interface() && !ik->has_subklass()) {
2421 // Add a dependence; if any subclass added we need to recompile
2422 if (!ik->is_final()) {
2423 // %%% should use stronger assert_unique_concrete_subtype instead
2424 phase->C->dependencies()->assert_leaf_type(ik);
2425 }
2426 // Return precise klass
2427 return TypeKlassPtr::make(ik);
2428 }
2429
2430 // Return root of possible klass
2431 return TypeInstKlassPtr::make(TypePtr::NotNull, ik, Type::Offset(0), tinst->flatten_array());
2432 }
2433 }
2434
2435 // Check for loading klass from an array
2436 const TypeAryPtr *tary = tp->isa_aryptr();
2437 if (tary != NULL) {
2438 ciKlass *tary_klass = tary->klass();
2439 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2440 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2441 if (tary->klass_is_exact()) {
2442 return TypeKlassPtr::make(tary_klass);
2443 }
2444 ciArrayKlass* ak = tary_klass->as_array_klass();
2445 // If the klass is an object array, we defer the question to the
2446 // array component klass.
2447 if (ak->is_obj_array_klass()) {
2448 assert(ak->is_loaded(), "");
2449 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2450 if (base_k->is_loaded() && base_k->is_instance_klass()) {
2451 ciInstanceKlass *ik = base_k->as_instance_klass();
2452 // See if we can become precise: no subklasses and no interface
2453 // Do not fold klass loads from [LMyValue. The runtime type might be [QMyValue due to [QMyValue <: [LMyValue
2454 // and the klass for [QMyValue is not equal to the klass for [LMyValue.
2455 if (!ik->is_interface() && !ik->has_subklass() && (!ik->is_inlinetype() || ak->is_elem_null_free())) {
2456 // Add a dependence; if any subclass added we need to recompile
2457 if (!ik->is_final()) {
2458 phase->C->dependencies()->assert_leaf_type(ik);
2459 }
2460 // Return precise array klass
2461 return TypeKlassPtr::make(ak);
2462 }
2463 }
2464 return TypeAryKlassPtr::make(TypePtr::NotNull, ak, Type::Offset(0), tary->is_not_flat(), tary->is_not_null_free(), tary->is_null_free());
2465 } else if (ak->is_type_array_klass()) {
2466 return TypeKlassPtr::make(ak); // These are always precise
2467 }
2468 }
2469 }
2470
2471 // Check for loading klass from an array klass
2472 const TypeKlassPtr *tkls = tp->isa_klassptr();
2473 if (tkls != NULL && !StressReflectiveCode) {
2474 if (!tkls->is_loaded()) {
2475 return _type; // Bail out if not loaded
2476 }
2477 ciKlass* klass = tkls->klass();
2478 if( klass->is_obj_array_klass() &&
2479 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2480 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2481 // // Always returning precise element type is incorrect,
2482 // // e.g., element type could be object and array may contain strings
2483 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2484
2485 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2486 // according to the element type's subclassing.
2487 return TypeKlassPtr::make(tkls->ptr(), elem, Type::Offset(0));
2488 } else if (klass->is_flat_array_klass() &&
2489 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2490 ciKlass* elem = klass->as_flat_array_klass()->element_klass();
2491 return TypeInstKlassPtr::make(tkls->ptr(), elem, Type::Offset(0), /* flatten_array= */ true);
2492 }
2493 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2494 tkls->offset() == in_bytes(Klass::super_offset())) {
2495 ciKlass* sup = klass->as_instance_klass()->super();
2496 // The field is Klass::_super. Return its (constant) value.
2497 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2498 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2499 }
2500 }
2501
2502 // Bailout case
2503 return LoadNode::Value(phase);
2504 }
2505
2506 //------------------------------Identity---------------------------------------
2507 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2508 // Also feed through the klass in Allocate(...klass...)._klass.
2509 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2510 return klass_identity_common(phase);
2511 }
2512
2513 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2514 Node* x = LoadNode::Identity(phase);
2515 if (x != this) return x;
2516
2517 // Take apart the address into an oop and and offset.
2518 // Return 'this' if we cannot.
2519 Node* adr = in(MemNode::Address);
2520 intptr_t offset = 0;
2521 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2522 if (base == NULL) return this;
2523 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2524 if (toop == NULL) return this;
2525
2526 // Step over potential GC barrier for OopHandle resolve
2527 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2528 if (bs->is_gc_barrier_node(base)) {
2529 base = bs->step_over_gc_barrier(base);
2530 }
2531
2532 // We can fetch the klass directly through an AllocateNode.
2533 // This works even if the klass is not constant (clone or newArray).
2534 if (offset == oopDesc::klass_offset_in_bytes()) {
2535 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2536 if (allocated_klass != NULL) {
2537 return allocated_klass;
2538 }
2539 }
2540
2541 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2542 // See inline_native_Class_query for occurrences of these patterns.
2543 // Java Example: x.getClass().isAssignableFrom(y)
2544 //
2545 // This improves reflective code, often making the Class
2546 // mirror go completely dead. (Current exception: Class
2547 // mirrors may appear in debug info, but we could clean them out by
2548 // introducing a new debug info operator for Klass.java_mirror).
2549
2550 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2551 && offset == java_lang_Class::klass_offset()) {
2552 if (base->is_Load()) {
2553 Node* base2 = base->in(MemNode::Address);
2554 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2555 Node* adr2 = base2->in(MemNode::Address);
2556 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2557 if (tkls != NULL && !tkls->empty()
2558 && (tkls->klass()->is_instance_klass() ||
2559 tkls->klass()->is_array_klass())
2560 && adr2->is_AddP()
2561 ) {
2562 int mirror_field = in_bytes(Klass::java_mirror_offset());
2563 if (tkls->offset() == mirror_field) {
2564 return adr2->in(AddPNode::Base);
2565 }
2566 }
2567 }
2568 }
2569 }
2570
2571 return this;
2572 }
2573
2574
2575 //------------------------------Value------------------------------------------
2576 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2577 const Type *t = klass_value_common(phase);
2578 if (t == Type::TOP)
2579 return t;
2580
2581 return t->make_narrowklass();
2582 }
2583
2584 //------------------------------Identity---------------------------------------
2585 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2586 // Also feed through the klass in Allocate(...klass...)._klass.
2587 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2588 Node *x = klass_identity_common(phase);
2589
2590 const Type *t = phase->type( x );
2591 if( t == Type::TOP ) return x;
2592 if( t->isa_narrowklass()) return x;
2593 assert (!t->isa_narrowoop(), "no narrow oop here");
2594
2595 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2596 }
2597
2598 //------------------------------Value-----------------------------------------
2599 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2600 // Either input is TOP ==> the result is TOP
2601 const Type *t1 = phase->type( in(MemNode::Memory) );
2602 if( t1 == Type::TOP ) return Type::TOP;
2603 Node *adr = in(MemNode::Address);
2604 const Type *t2 = phase->type( adr );
2605 if( t2 == Type::TOP ) return Type::TOP;
2606 const TypePtr *tp = t2->is_ptr();
2607 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2608 const TypeAryPtr *tap = tp->isa_aryptr();
2609 if( !tap ) return _type;
2610 return tap->size();
2611 }
2612
2613 //-------------------------------Ideal---------------------------------------
2614 // Feed through the length in AllocateArray(...length...)._length.
2615 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2616 Node* p = MemNode::Ideal_common(phase, can_reshape);
2617 if (p) return (p == NodeSentinel) ? NULL : p;
2618
2619 // Take apart the address into an oop and and offset.
2620 // Return 'this' if we cannot.
2621 Node* adr = in(MemNode::Address);
2622 intptr_t offset = 0;
2623 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2624 if (base == NULL) return NULL;
2625 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2626 if (tary == NULL) return NULL;
2627
2628 // We can fetch the length directly through an AllocateArrayNode.
2629 // This works even if the length is not constant (clone or newArray).
2630 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2631 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2632 if (alloc != NULL) {
2633 Node* allocated_length = alloc->Ideal_length();
2634 Node* len = alloc->make_ideal_length(tary, phase);
2635 if (allocated_length != len) {
2636 // New CastII improves on this.
2637 return len;
2638 }
2639 }
2640 }
2641
2642 return NULL;
2643 }
2644
2645 //------------------------------Identity---------------------------------------
2646 // Feed through the length in AllocateArray(...length...)._length.
2647 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2648 Node* x = LoadINode::Identity(phase);
2649 if (x != this) return x;
2650
2651 // Take apart the address into an oop and and offset.
2652 // Return 'this' if we cannot.
2653 Node* adr = in(MemNode::Address);
2654 intptr_t offset = 0;
2655 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2656 if (base == NULL) return this;
2657 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2658 if (tary == NULL) return this;
2659
2660 // We can fetch the length directly through an AllocateArrayNode.
2661 // This works even if the length is not constant (clone or newArray).
2662 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2663 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2664 if (alloc != NULL) {
2665 Node* allocated_length = alloc->Ideal_length();
2666 // Do not allow make_ideal_length to allocate a CastII node.
2667 Node* len = alloc->make_ideal_length(tary, phase, false);
2668 if (allocated_length == len) {
2669 // Return allocated_length only if it would not be improved by a CastII.
2670 return allocated_length;
2671 }
2672 }
2673 }
2674
2675 return this;
2676
2677 }
2678
2679 //=============================================================================
2680 //---------------------------StoreNode::make-----------------------------------
2681 // Polymorphic factory method:
2682 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2683 assert((mo == unordered || mo == release), "unexpected");
2684 Compile* C = gvn.C;
2685 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2686 ctl != NULL, "raw memory operations should have control edge");
2687
2688 switch (bt) {
2689 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2690 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2691 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2692 case T_CHAR:
2693 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2694 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2695 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2696 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2697 case T_METADATA:
2698 case T_ADDRESS:
2699 case T_PRIMITIVE_OBJECT:
2700 case T_OBJECT:
2701 #ifdef _LP64
2702 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2703 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2704 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2705 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2706 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2707 adr->bottom_type()->isa_rawptr())) {
2708 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2709 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2710 }
2711 #endif
2712 {
2713 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2714 }
2715 default:
2716 ShouldNotReachHere();
2717 return (StoreNode*)NULL;
2718 }
2719 }
2720
2721 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2722 bool require_atomic = true;
2723 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2724 }
2725
2726 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2727 bool require_atomic = true;
2728 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2729 }
2730
2731
2732 //--------------------------bottom_type----------------------------------------
2733 const Type *StoreNode::bottom_type() const {
2734 return Type::MEMORY;
2735 }
2736
2737 //------------------------------hash-------------------------------------------
2738 uint StoreNode::hash() const {
2739 // unroll addition of interesting fields
2740 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2741
2742 // Since they are not commoned, do not hash them:
2743 return NO_HASH;
2744 }
2745
2746 //------------------------------Ideal------------------------------------------
2747 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2748 // When a store immediately follows a relevant allocation/initialization,
2749 // try to capture it into the initialization, or hoist it above.
2750 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2751 Node* p = MemNode::Ideal_common(phase, can_reshape);
2752 if (p) return (p == NodeSentinel) ? NULL : p;
2753
2754 Node* mem = in(MemNode::Memory);
2755 Node* address = in(MemNode::Address);
2756 Node* value = in(MemNode::ValueIn);
2757 // Back-to-back stores to same address? Fold em up. Generally
2758 // unsafe if I have intervening uses... Also disallowed for StoreCM
2759 // since they must follow each StoreP operation. Redundant StoreCMs
2760 // are eliminated just before matching in final_graph_reshape.
2761 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
2762 Node* st = mem;
2763 // If Store 'st' has more than one use, we cannot fold 'st' away.
2764 // For example, 'st' might be the final state at a conditional
2765 // return. Or, 'st' might be used by some node which is live at
2766 // the same time 'st' is live, which might be unschedulable. So,
2767 // require exactly ONE user until such time as we clone 'mem' for
2768 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2769 // true).
2770 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2771 // Looking at a dead closed cycle of memory?
2772 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2773 assert(Opcode() == st->Opcode() ||
2774 st->Opcode() == Op_StoreVector ||
2775 Opcode() == Op_StoreVector ||
2776 st->Opcode() == Op_StoreVectorScatter ||
2777 Opcode() == Op_StoreVectorScatter ||
2778 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2779 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2780 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2781 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2782 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2783 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2784
2785 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2786 st->as_Store()->memory_size() <= this->memory_size()) {
2787 Node* use = st->raw_out(0);
2788 if (phase->is_IterGVN()) {
2789 phase->is_IterGVN()->rehash_node_delayed(use);
2790 }
2791 // It's OK to do this in the parser, since DU info is always accurate,
2792 // and the parser always refers to nodes via SafePointNode maps.
2793 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2794 return this;
2795 }
2796 st = st->in(MemNode::Memory);
2797 }
2798 }
2799
2800
2801 // Capture an unaliased, unconditional, simple store into an initializer.
2802 // Or, if it is independent of the allocation, hoist it above the allocation.
2803 if (ReduceFieldZeroing && /*can_reshape &&*/
2804 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2805 InitializeNode* init = mem->in(0)->as_Initialize();
2806 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2807 if (offset > 0) {
2808 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2809 // If the InitializeNode captured me, it made a raw copy of me,
2810 // and I need to disappear.
2811 if (moved != NULL) {
2812 // %%% hack to ensure that Ideal returns a new node:
2813 mem = MergeMemNode::make(mem);
2814 return mem; // fold me away
2815 }
2816 }
2817 }
2818
2819 // Fold reinterpret cast into memory operation:
2820 // StoreX mem (MoveY2X v) => StoreY mem v
2821 if (value->is_Move()) {
2822 const Type* vt = value->in(1)->bottom_type();
2823 if (has_reinterpret_variant(vt)) {
2824 if (phase->C->post_loop_opts_phase()) {
2825 return convert_to_reinterpret_store(*phase, value->in(1), vt);
2826 } else {
2827 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2828 }
2829 }
2830 }
2831
2832 return NULL; // No further progress
2833 }
2834
2835 //------------------------------Value-----------------------------------------
2836 const Type* StoreNode::Value(PhaseGVN* phase) const {
2837 // Either input is TOP ==> the result is TOP
2838 const Type *t1 = phase->type( in(MemNode::Memory) );
2839 if( t1 == Type::TOP ) return Type::TOP;
2840 const Type *t2 = phase->type( in(MemNode::Address) );
2841 if( t2 == Type::TOP ) return Type::TOP;
2842 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2843 if( t3 == Type::TOP ) return Type::TOP;
2844 return Type::MEMORY;
2845 }
2846
2847 //------------------------------Identity---------------------------------------
2848 // Remove redundant stores:
2849 // Store(m, p, Load(m, p)) changes to m.
2850 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2851 Node* StoreNode::Identity(PhaseGVN* phase) {
2852 Node* mem = in(MemNode::Memory);
2853 Node* adr = in(MemNode::Address);
2854 Node* val = in(MemNode::ValueIn);
2855
2856 Node* result = this;
2857
2858 // Load then Store? Then the Store is useless
2859 if (val->is_Load() &&
2860 val->in(MemNode::Address)->eqv_uncast(adr) &&
2861 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2862 val->as_Load()->store_Opcode() == Opcode()) {
2863 result = mem;
2864 }
2865
2866 // Two stores in a row of the same value?
2867 if (result == this &&
2868 mem->is_Store() &&
2869 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2870 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2871 mem->Opcode() == Opcode()) {
2872 result = mem;
2873 }
2874
2875 // Store of zero anywhere into a freshly-allocated object?
2876 // Then the store is useless.
2877 // (It must already have been captured by the InitializeNode.)
2878 if (result == this && ReduceFieldZeroing) {
2879 // a newly allocated object is already all-zeroes everywhere
2880 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2881 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2882 assert(!phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == NULL, "storing null to inline type array is forbidden");
2883 result = mem;
2884 }
2885
2886 if (result == this && phase->type(val)->is_zero_type()) {
2887 // the store may also apply to zero-bits in an earlier object
2888 Node* prev_mem = find_previous_store(phase);
2889 // Steps (a), (b): Walk past independent stores to find an exact match.
2890 if (prev_mem != NULL) {
2891 Node* prev_val = can_see_stored_value(prev_mem, phase);
2892 if (prev_val != NULL && prev_val == val) {
2893 // prev_val and val might differ by a cast; it would be good
2894 // to keep the more informative of the two.
2895 result = mem;
2896 }
2897 }
2898 }
2899 }
2900
2901 PhaseIterGVN* igvn = phase->is_IterGVN();
2902 if (result != this && igvn != NULL) {
2903 MemBarNode* trailing = trailing_membar();
2904 if (trailing != NULL) {
2905 #ifdef ASSERT
2906 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2907 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2908 #endif
2909 trailing->remove(igvn);
2910 }
2911 }
2912
2913 return result;
2914 }
2915
2916 //------------------------------match_edge-------------------------------------
2917 // Do we Match on this edge index or not? Match only memory & value
2918 uint StoreNode::match_edge(uint idx) const {
2919 return idx == MemNode::Address || idx == MemNode::ValueIn;
2920 }
2921
2922 //------------------------------cmp--------------------------------------------
2923 // Do not common stores up together. They generally have to be split
2924 // back up anyways, so do not bother.
2925 bool StoreNode::cmp( const Node &n ) const {
2926 return (&n == this); // Always fail except on self
2927 }
2928
2929 //------------------------------Ideal_masked_input-----------------------------
2930 // Check for a useless mask before a partial-word store
2931 // (StoreB ... (AndI valIn conIa) )
2932 // If (conIa & mask == mask) this simplifies to
2933 // (StoreB ... (valIn) )
2934 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2935 Node *val = in(MemNode::ValueIn);
2936 if( val->Opcode() == Op_AndI ) {
2937 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2938 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2939 set_req_X(MemNode::ValueIn, val->in(1), phase);
2940 return this;
2941 }
2942 }
2943 return NULL;
2944 }
2945
2946
2947 //------------------------------Ideal_sign_extended_input----------------------
2948 // Check for useless sign-extension before a partial-word store
2949 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2950 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2951 // (StoreB ... (valIn) )
2952 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2953 Node *val = in(MemNode::ValueIn);
2954 if( val->Opcode() == Op_RShiftI ) {
2955 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2956 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2957 Node *shl = val->in(1);
2958 if( shl->Opcode() == Op_LShiftI ) {
2959 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2960 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2961 set_req_X(MemNode::ValueIn, shl->in(1), phase);
2962 return this;
2963 }
2964 }
2965 }
2966 }
2967 return NULL;
2968 }
2969
2970 //------------------------------value_never_loaded-----------------------------------
2971 // Determine whether there are any possible loads of the value stored.
2972 // For simplicity, we actually check if there are any loads from the
2973 // address stored to, not just for loads of the value stored by this node.
2974 //
2975 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2976 Node *adr = in(Address);
2977 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2978 if (adr_oop == NULL)
2979 return false;
2980 if (!adr_oop->is_known_instance_field())
2981 return false; // if not a distinct instance, there may be aliases of the address
2982 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2983 Node *use = adr->fast_out(i);
2984 if (use->is_Load() || use->is_LoadStore()) {
2985 return false;
2986 }
2987 }
2988 return true;
2989 }
2990
2991 MemBarNode* StoreNode::trailing_membar() const {
2992 if (is_release()) {
2993 MemBarNode* trailing_mb = NULL;
2994 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2995 Node* u = fast_out(i);
2996 if (u->is_MemBar()) {
2997 if (u->as_MemBar()->trailing_store()) {
2998 assert(u->Opcode() == Op_MemBarVolatile, "");
2999 assert(trailing_mb == NULL, "only one");
3000 trailing_mb = u->as_MemBar();
3001 #ifdef ASSERT
3002 Node* leading = u->as_MemBar()->leading_membar();
3003 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3004 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
3005 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
3006 #endif
3007 } else {
3008 assert(u->as_MemBar()->standalone(), "");
3009 }
3010 }
3011 }
3012 return trailing_mb;
3013 }
3014 return NULL;
3015 }
3016
3017
3018 //=============================================================================
3019 //------------------------------Ideal------------------------------------------
3020 // If the store is from an AND mask that leaves the low bits untouched, then
3021 // we can skip the AND operation. If the store is from a sign-extension
3022 // (a left shift, then right shift) we can skip both.
3023 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
3024 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
3025 if( progress != NULL ) return progress;
3026
3027 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
3028 if( progress != NULL ) return progress;
3029
3030 // Finally check the default case
3031 return StoreNode::Ideal(phase, can_reshape);
3032 }
3033
3034 //=============================================================================
3035 //------------------------------Ideal------------------------------------------
3036 // If the store is from an AND mask that leaves the low bits untouched, then
3037 // we can skip the AND operation
3038 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
3039 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
3040 if( progress != NULL ) return progress;
3041
3042 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
3043 if( progress != NULL ) return progress;
3044
3045 // Finally check the default case
3046 return StoreNode::Ideal(phase, can_reshape);
3047 }
3048
3049 //=============================================================================
3050 //------------------------------Identity---------------------------------------
3051 Node* StoreCMNode::Identity(PhaseGVN* phase) {
3052 // No need to card mark when storing a null ptr
3053 Node* my_store = in(MemNode::OopStore);
3054 if (my_store->is_Store()) {
3055 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
3056 if( t1 == TypePtr::NULL_PTR ) {
3057 return in(MemNode::Memory);
3058 }
3059 }
3060 return this;
3061 }
3062
3063 //=============================================================================
3064 //------------------------------Ideal---------------------------------------
3065 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
3066 Node* progress = StoreNode::Ideal(phase, can_reshape);
3067 if (progress != NULL) return progress;
3068
3069 Node* my_store = in(MemNode::OopStore);
3070 if (my_store->is_MergeMem()) {
3071 if (oop_alias_idx() != phase->C->get_alias_index(TypeAryPtr::INLINES) ||
3072 phase->C->flattened_accesses_share_alias()) {
3073 // The alias that was recorded is no longer accurate enough.
3074 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
3075 set_req_X(MemNode::OopStore, mem, phase);
3076 return this;
3077 }
3078 }
3079
3080 return NULL;
3081 }
3082
3083 //------------------------------Value-----------------------------------------
3084 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
3085 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
3086 // If extra input is TOP ==> the result is TOP
3087 const Type* t = phase->type(in(MemNode::OopStore));
3088 if (t == Type::TOP) {
3089 return Type::TOP;
3090 }
3091 return StoreNode::Value(phase);
3092 }
3093
3094
3095 //=============================================================================
3096 //----------------------------------SCMemProjNode------------------------------
3097 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3098 {
3099 if (in(0) == NULL || phase->type(in(0)) == Type::TOP) {
3100 return Type::TOP;
3101 }
3102 return bottom_type();
3103 }
3104
3105 //=============================================================================
3106 //----------------------------------LoadStoreNode------------------------------
3107 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3108 : Node(required),
3109 _type(rt),
3110 _adr_type(at),
3111 _barrier_data(0)
3112 {
3113 init_req(MemNode::Control, c );
3114 init_req(MemNode::Memory , mem);
3115 init_req(MemNode::Address, adr);
3116 init_req(MemNode::ValueIn, val);
3117 init_class_id(Class_LoadStore);
3118 }
3119
3120 //------------------------------Value-----------------------------------------
3121 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3122 // Either input is TOP ==> the result is TOP
3123 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3124 return Type::TOP;
3125 }
3126 const Type* t = phase->type(in(MemNode::Memory));
3127 if (t == Type::TOP) {
3128 return Type::TOP;
3129 }
3130 t = phase->type(in(MemNode::Address));
3131 if (t == Type::TOP) {
3132 return Type::TOP;
3133 }
3134 t = phase->type(in(MemNode::ValueIn));
3135 if (t == Type::TOP) {
3136 return Type::TOP;
3137 }
3138 return bottom_type();
3139 }
3140
3141 uint LoadStoreNode::ideal_reg() const {
3142 return _type->ideal_reg();
3143 }
3144
3145 bool LoadStoreNode::result_not_used() const {
3146 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3147 Node *x = fast_out(i);
3148 if (x->Opcode() == Op_SCMemProj) continue;
3149 return false;
3150 }
3151 return true;
3152 }
3153
3154 MemBarNode* LoadStoreNode::trailing_membar() const {
3155 MemBarNode* trailing = NULL;
3156 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3157 Node* u = fast_out(i);
3158 if (u->is_MemBar()) {
3159 if (u->as_MemBar()->trailing_load_store()) {
3160 assert(u->Opcode() == Op_MemBarAcquire, "");
3161 assert(trailing == NULL, "only one");
3162 trailing = u->as_MemBar();
3163 #ifdef ASSERT
3164 Node* leading = trailing->leading_membar();
3165 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3166 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3167 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3168 #endif
3169 } else {
3170 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3171 }
3172 }
3173 }
3174
3175 return trailing;
3176 }
3177
3178 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3179
3180 //=============================================================================
3181 //----------------------------------LoadStoreConditionalNode--------------------
3182 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
3183 init_req(ExpectedIn, ex );
3184 }
3185
3186 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3187 // Either input is TOP ==> the result is TOP
3188 const Type* t = phase->type(in(ExpectedIn));
3189 if (t == Type::TOP) {
3190 return Type::TOP;
3191 }
3192 return LoadStoreNode::Value(phase);
3193 }
3194
3195 //=============================================================================
3196 //-------------------------------adr_type--------------------------------------
3197 const TypePtr* ClearArrayNode::adr_type() const {
3198 Node *adr = in(3);
3199 if (adr == NULL) return NULL; // node is dead
3200 return MemNode::calculate_adr_type(adr->bottom_type());
3201 }
3202
3203 //------------------------------match_edge-------------------------------------
3204 // Do we Match on this edge index or not? Do not match memory
3205 uint ClearArrayNode::match_edge(uint idx) const {
3206 return idx > 1;
3207 }
3208
3209 //------------------------------Identity---------------------------------------
3210 // Clearing a zero length array does nothing
3211 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3212 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3213 }
3214
3215 //------------------------------Idealize---------------------------------------
3216 // Clearing a short array is faster with stores
3217 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3218 // Already know this is a large node, do not try to ideal it
3219 if (!IdealizeClearArrayNode || _is_large) return NULL;
3220
3221 const int unit = BytesPerLong;
3222 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3223 if (!t) return NULL;
3224 if (!t->is_con()) return NULL;
3225 intptr_t raw_count = t->get_con();
3226 intptr_t size = raw_count;
3227 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3228 // Clearing nothing uses the Identity call.
3229 // Negative clears are possible on dead ClearArrays
3230 // (see jck test stmt114.stmt11402.val).
3231 if (size <= 0 || size % unit != 0) return NULL;
3232 intptr_t count = size / unit;
3233 // Length too long; communicate this to matchers and assemblers.
3234 // Assemblers are responsible to produce fast hardware clears for it.
3235 if (size > InitArrayShortSize) {
3236 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
3237 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3238 return NULL;
3239 }
3240 Node *mem = in(1);
3241 if( phase->type(mem)==Type::TOP ) return NULL;
3242 Node *adr = in(3);
3243 const Type* at = phase->type(adr);
3244 if( at==Type::TOP ) return NULL;
3245 const TypePtr* atp = at->isa_ptr();
3246 // adjust atp to be the correct array element address type
3247 if (atp == NULL) atp = TypePtr::BOTTOM;
3248 else atp = atp->add_offset(Type::OffsetBot);
3249 // Get base for derived pointer purposes
3250 if( adr->Opcode() != Op_AddP ) Unimplemented();
3251 Node *base = adr->in(1);
3252
3253 Node *val = in(4);
3254 Node *off = phase->MakeConX(BytesPerLong);
3255 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3256 count--;
3257 while( count-- ) {
3258 mem = phase->transform(mem);
3259 adr = phase->transform(new AddPNode(base,adr,off));
3260 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3261 }
3262 return mem;
3263 }
3264
3265 //----------------------------step_through----------------------------------
3266 // Return allocation input memory edge if it is different instance
3267 // or itself if it is the one we are looking for.
3268 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3269 Node* n = *np;
3270 assert(n->is_ClearArray(), "sanity");
3271 intptr_t offset;
3272 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3273 // This method is called only before Allocate nodes are expanded
3274 // during macro nodes expansion. Before that ClearArray nodes are
3275 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3276 // Allocate nodes are expanded) which follows allocations.
3277 assert(alloc != NULL, "should have allocation");
3278 if (alloc->_idx == instance_id) {
3279 // Can not bypass initialization of the instance we are looking for.
3280 return false;
3281 }
3282 // Otherwise skip it.
3283 InitializeNode* init = alloc->initialization();
3284 if (init != NULL)
3285 *np = init->in(TypeFunc::Memory);
3286 else
3287 *np = alloc->in(TypeFunc::Memory);
3288 return true;
3289 }
3290
3291 //----------------------------clear_memory-------------------------------------
3292 // Generate code to initialize object storage to zero.
3293 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3294 Node* val,
3295 Node* raw_val,
3296 intptr_t start_offset,
3297 Node* end_offset,
3298 PhaseGVN* phase) {
3299 intptr_t offset = start_offset;
3300
3301 int unit = BytesPerLong;
3302 if ((offset % unit) != 0) {
3303 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3304 adr = phase->transform(adr);
3305 const TypePtr* atp = TypeRawPtr::BOTTOM;
3306 if (val != NULL) {
3307 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3308 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3309 } else {
3310 assert(raw_val == NULL, "val may not be null");
3311 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3312 }
3313 mem = phase->transform(mem);
3314 offset += BytesPerInt;
3315 }
3316 assert((offset % unit) == 0, "");
3317
3318 // Initialize the remaining stuff, if any, with a ClearArray.
3319 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3320 }
3321
3322 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3323 Node* raw_val,
3324 Node* start_offset,
3325 Node* end_offset,
3326 PhaseGVN* phase) {
3327 if (start_offset == end_offset) {
3328 // nothing to do
3329 return mem;
3330 }
3331
3332 int unit = BytesPerLong;
3333 Node* zbase = start_offset;
3334 Node* zend = end_offset;
3335
3336 // Scale to the unit required by the CPU:
3337 if (!Matcher::init_array_count_is_in_bytes) {
3338 Node* shift = phase->intcon(exact_log2(unit));
3339 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3340 zend = phase->transform(new URShiftXNode(zend, shift) );
3341 }
3342
3343 // Bulk clear double-words
3344 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3345 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3346 if (raw_val == NULL) {
3347 raw_val = phase->MakeConX(0);
3348 }
3349 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3350 return phase->transform(mem);
3351 }
3352
3353 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3354 Node* val,
3355 Node* raw_val,
3356 intptr_t start_offset,
3357 intptr_t end_offset,
3358 PhaseGVN* phase) {
3359 if (start_offset == end_offset) {
3360 // nothing to do
3361 return mem;
3362 }
3363
3364 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3365 intptr_t done_offset = end_offset;
3366 if ((done_offset % BytesPerLong) != 0) {
3367 done_offset -= BytesPerInt;
3368 }
3369 if (done_offset > start_offset) {
3370 mem = clear_memory(ctl, mem, dest, val, raw_val,
3371 start_offset, phase->MakeConX(done_offset), phase);
3372 }
3373 if (done_offset < end_offset) { // emit the final 32-bit store
3374 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3375 adr = phase->transform(adr);
3376 const TypePtr* atp = TypeRawPtr::BOTTOM;
3377 if (val != NULL) {
3378 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3379 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3380 } else {
3381 assert(raw_val == NULL, "val may not be null");
3382 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3383 }
3384 mem = phase->transform(mem);
3385 done_offset += BytesPerInt;
3386 }
3387 assert(done_offset == end_offset, "");
3388 return mem;
3389 }
3390
3391 //=============================================================================
3392 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3393 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3394 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3395 #ifdef ASSERT
3396 , _pair_idx(0)
3397 #endif
3398 {
3399 init_class_id(Class_MemBar);
3400 Node* top = C->top();
3401 init_req(TypeFunc::I_O,top);
3402 init_req(TypeFunc::FramePtr,top);
3403 init_req(TypeFunc::ReturnAdr,top);
3404 if (precedent != NULL)
3405 init_req(TypeFunc::Parms, precedent);
3406 }
3407
3408 //------------------------------cmp--------------------------------------------
3409 uint MemBarNode::hash() const { return NO_HASH; }
3410 bool MemBarNode::cmp( const Node &n ) const {
3411 return (&n == this); // Always fail except on self
3412 }
3413
3414 //------------------------------make-------------------------------------------
3415 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3416 switch (opcode) {
3417 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3418 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3419 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3420 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3421 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3422 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
3423 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3424 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3425 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3426 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3427 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3428 case Op_Initialize: return new InitializeNode(C, atp, pn);
3429 case Op_Blackhole: return new BlackholeNode(C, atp, pn);
3430 default: ShouldNotReachHere(); return NULL;
3431 }
3432 }
3433
3434 void MemBarNode::remove(PhaseIterGVN *igvn) {
3435 if (outcnt() != 2) {
3436 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3437 assert(outcnt() == 1, "Only control then");
3438 }
3439 if (trailing_store() || trailing_load_store()) {
3440 MemBarNode* leading = leading_membar();
3441 if (leading != NULL) {
3442 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3443 leading->remove(igvn);
3444 }
3445 }
3446 if (proj_out_or_null(TypeFunc::Memory) != NULL) {
3447 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3448 }
3449 if (proj_out_or_null(TypeFunc::Control) != NULL) {
3450 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3451 }
3452 }
3453
3454 //------------------------------Ideal------------------------------------------
3455 // Return a node which is more "ideal" than the current node. Strip out
3456 // control copies
3457 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3458 if (remove_dead_region(phase, can_reshape)) return this;
3459 // Don't bother trying to transform a dead node
3460 if (in(0) && in(0)->is_top()) {
3461 return NULL;
3462 }
3463
3464 bool progress = false;
3465 // Eliminate volatile MemBars for scalar replaced objects.
3466 if (can_reshape && req() == (Precedent+1)) {
3467 bool eliminate = false;
3468 int opc = Opcode();
3469 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3470 // Volatile field loads and stores.
3471 Node* my_mem = in(MemBarNode::Precedent);
3472 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3473 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3474 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3475 // replace this Precedent (decodeN) with the Load instead.
3476 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3477 Node* load_node = my_mem->in(1);
3478 set_req(MemBarNode::Precedent, load_node);
3479 phase->is_IterGVN()->_worklist.push(my_mem);
3480 my_mem = load_node;
3481 } else {
3482 assert(my_mem->unique_out() == this, "sanity");
3483 del_req(Precedent);
3484 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3485 my_mem = NULL;
3486 }
3487 progress = true;
3488 }
3489 if (my_mem != NULL && my_mem->is_Mem()) {
3490 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3491 // Check for scalar replaced object reference.
3492 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3493 t_oop->offset() != Type::OffsetBot &&
3494 t_oop->offset() != Type::OffsetTop) {
3495 eliminate = true;
3496 }
3497 }
3498 } else if (opc == Op_MemBarRelease) {
3499 // Final field stores.
3500 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3501 if ((alloc != NULL) && alloc->is_Allocate() &&
3502 alloc->as_Allocate()->does_not_escape_thread()) {
3503 // The allocated object does not escape.
3504 eliminate = true;
3505 }
3506 }
3507 if (eliminate) {
3508 // Replace MemBar projections by its inputs.
3509 PhaseIterGVN* igvn = phase->is_IterGVN();
3510 remove(igvn);
3511 // Must return either the original node (now dead) or a new node
3512 // (Do not return a top here, since that would break the uniqueness of top.)
3513 return new ConINode(TypeInt::ZERO);
3514 }
3515 }
3516 return progress ? this : NULL;
3517 }
3518
3519 //------------------------------Value------------------------------------------
3520 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3521 if( !in(0) ) return Type::TOP;
3522 if( phase->type(in(0)) == Type::TOP )
3523 return Type::TOP;
3524 return TypeTuple::MEMBAR;
3525 }
3526
3527 //------------------------------match------------------------------------------
3528 // Construct projections for memory.
3529 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3530 switch (proj->_con) {
3531 case TypeFunc::Control:
3532 case TypeFunc::Memory:
3533 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3534 }
3535 ShouldNotReachHere();
3536 return NULL;
3537 }
3538
3539 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3540 trailing->_kind = TrailingStore;
3541 leading->_kind = LeadingStore;
3542 #ifdef ASSERT
3543 trailing->_pair_idx = leading->_idx;
3544 leading->_pair_idx = leading->_idx;
3545 #endif
3546 }
3547
3548 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3549 trailing->_kind = TrailingLoadStore;
3550 leading->_kind = LeadingLoadStore;
3551 #ifdef ASSERT
3552 trailing->_pair_idx = leading->_idx;
3553 leading->_pair_idx = leading->_idx;
3554 #endif
3555 }
3556
3557 MemBarNode* MemBarNode::trailing_membar() const {
3558 ResourceMark rm;
3559 Node* trailing = (Node*)this;
3560 VectorSet seen;
3561 Node_Stack multis(0);
3562 do {
3563 Node* c = trailing;
3564 uint i = 0;
3565 do {
3566 trailing = NULL;
3567 for (; i < c->outcnt(); i++) {
3568 Node* next = c->raw_out(i);
3569 if (next != c && next->is_CFG()) {
3570 if (c->is_MultiBranch()) {
3571 if (multis.node() == c) {
3572 multis.set_index(i+1);
3573 } else {
3574 multis.push(c, i+1);
3575 }
3576 }
3577 trailing = next;
3578 break;
3579 }
3580 }
3581 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3582 break;
3583 }
3584 while (multis.size() > 0) {
3585 c = multis.node();
3586 i = multis.index();
3587 if (i < c->req()) {
3588 break;
3589 }
3590 multis.pop();
3591 }
3592 } while (multis.size() > 0);
3593 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3594
3595 MemBarNode* mb = trailing->as_MemBar();
3596 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3597 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3598 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3599 return mb;
3600 }
3601
3602 MemBarNode* MemBarNode::leading_membar() const {
3603 ResourceMark rm;
3604 VectorSet seen;
3605 Node_Stack regions(0);
3606 Node* leading = in(0);
3607 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3608 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3609 leading = NULL;
3610 while (regions.size() > 0 && leading == NULL) {
3611 Node* r = regions.node();
3612 uint i = regions.index();
3613 if (i < r->req()) {
3614 leading = r->in(i);
3615 regions.set_index(i+1);
3616 } else {
3617 regions.pop();
3618 }
3619 }
3620 if (leading == NULL) {
3621 assert(regions.size() == 0, "all paths should have been tried");
3622 return NULL;
3623 }
3624 }
3625 if (leading->is_Region()) {
3626 regions.push(leading, 2);
3627 leading = leading->in(1);
3628 } else {
3629 leading = leading->in(0);
3630 }
3631 }
3632 #ifdef ASSERT
3633 Unique_Node_List wq;
3634 wq.push((Node*)this);
3635 uint found = 0;
3636 for (uint i = 0; i < wq.size(); i++) {
3637 Node* n = wq.at(i);
3638 if (n->is_Region()) {
3639 for (uint j = 1; j < n->req(); j++) {
3640 Node* in = n->in(j);
3641 if (in != NULL && !in->is_top()) {
3642 wq.push(in);
3643 }
3644 }
3645 } else {
3646 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3647 assert(n == leading, "consistency check failed");
3648 found++;
3649 } else {
3650 Node* in = n->in(0);
3651 if (in != NULL && !in->is_top()) {
3652 wq.push(in);
3653 }
3654 }
3655 }
3656 }
3657 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3658 #endif
3659 if (leading == NULL) {
3660 return NULL;
3661 }
3662 MemBarNode* mb = leading->as_MemBar();
3663 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3664 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3665 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3666 return mb;
3667 }
3668
3669 #ifndef PRODUCT
3670 void BlackholeNode::format(PhaseRegAlloc* ra, outputStream* st) const {
3671 st->print("blackhole ");
3672 bool first = true;
3673 for (uint i = 0; i < req(); i++) {
3674 Node* n = in(i);
3675 if (n != NULL && OptoReg::is_valid(ra->get_reg_first(n))) {
3676 if (first) {
3677 first = false;
3678 } else {
3679 st->print(", ");
3680 }
3681 char buf[128];
3682 ra->dump_register(n, buf);
3683 st->print("%s", buf);
3684 }
3685 }
3686 st->cr();
3687 }
3688 #endif
3689
3690 //===========================InitializeNode====================================
3691 // SUMMARY:
3692 // This node acts as a memory barrier on raw memory, after some raw stores.
3693 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3694 // The Initialize can 'capture' suitably constrained stores as raw inits.
3695 // It can coalesce related raw stores into larger units (called 'tiles').
3696 // It can avoid zeroing new storage for memory units which have raw inits.
3697 // At macro-expansion, it is marked 'complete', and does not optimize further.
3698 //
3699 // EXAMPLE:
3700 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3701 // ctl = incoming control; mem* = incoming memory
3702 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3703 // First allocate uninitialized memory and fill in the header:
3704 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3705 // ctl := alloc.Control; mem* := alloc.Memory*
3706 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3707 // Then initialize to zero the non-header parts of the raw memory block:
3708 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3709 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3710 // After the initialize node executes, the object is ready for service:
3711 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3712 // Suppose its body is immediately initialized as {1,2}:
3713 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3714 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3715 // mem.SLICE(#short[*]) := store2
3716 //
3717 // DETAILS:
3718 // An InitializeNode collects and isolates object initialization after
3719 // an AllocateNode and before the next possible safepoint. As a
3720 // memory barrier (MemBarNode), it keeps critical stores from drifting
3721 // down past any safepoint or any publication of the allocation.
3722 // Before this barrier, a newly-allocated object may have uninitialized bits.
3723 // After this barrier, it may be treated as a real oop, and GC is allowed.
3724 //
3725 // The semantics of the InitializeNode include an implicit zeroing of
3726 // the new object from object header to the end of the object.
3727 // (The object header and end are determined by the AllocateNode.)
3728 //
3729 // Certain stores may be added as direct inputs to the InitializeNode.
3730 // These stores must update raw memory, and they must be to addresses
3731 // derived from the raw address produced by AllocateNode, and with
3732 // a constant offset. They must be ordered by increasing offset.
3733 // The first one is at in(RawStores), the last at in(req()-1).
3734 // Unlike most memory operations, they are not linked in a chain,
3735 // but are displayed in parallel as users of the rawmem output of
3736 // the allocation.
3737 //
3738 // (See comments in InitializeNode::capture_store, which continue
3739 // the example given above.)
3740 //
3741 // When the associated Allocate is macro-expanded, the InitializeNode
3742 // may be rewritten to optimize collected stores. A ClearArrayNode
3743 // may also be created at that point to represent any required zeroing.
3744 // The InitializeNode is then marked 'complete', prohibiting further
3745 // capturing of nearby memory operations.
3746 //
3747 // During macro-expansion, all captured initializations which store
3748 // constant values of 32 bits or smaller are coalesced (if advantageous)
3749 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3750 // initialized in fewer memory operations. Memory words which are
3751 // covered by neither tiles nor non-constant stores are pre-zeroed
3752 // by explicit stores of zero. (The code shape happens to do all
3753 // zeroing first, then all other stores, with both sequences occurring
3754 // in order of ascending offsets.)
3755 //
3756 // Alternatively, code may be inserted between an AllocateNode and its
3757 // InitializeNode, to perform arbitrary initialization of the new object.
3758 // E.g., the object copying intrinsics insert complex data transfers here.
3759 // The initialization must then be marked as 'complete' disable the
3760 // built-in zeroing semantics and the collection of initializing stores.
3761 //
3762 // While an InitializeNode is incomplete, reads from the memory state
3763 // produced by it are optimizable if they match the control edge and
3764 // new oop address associated with the allocation/initialization.
3765 // They return a stored value (if the offset matches) or else zero.
3766 // A write to the memory state, if it matches control and address,
3767 // and if it is to a constant offset, may be 'captured' by the
3768 // InitializeNode. It is cloned as a raw memory operation and rewired
3769 // inside the initialization, to the raw oop produced by the allocation.
3770 // Operations on addresses which are provably distinct (e.g., to
3771 // other AllocateNodes) are allowed to bypass the initialization.
3772 //
3773 // The effect of all this is to consolidate object initialization
3774 // (both arrays and non-arrays, both piecewise and bulk) into a
3775 // single location, where it can be optimized as a unit.
3776 //
3777 // Only stores with an offset less than TrackedInitializationLimit words
3778 // will be considered for capture by an InitializeNode. This puts a
3779 // reasonable limit on the complexity of optimized initializations.
3780
3781 //---------------------------InitializeNode------------------------------------
3782 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3783 : MemBarNode(C, adr_type, rawoop),
3784 _is_complete(Incomplete), _does_not_escape(false)
3785 {
3786 init_class_id(Class_Initialize);
3787
3788 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3789 assert(in(RawAddress) == rawoop, "proper init");
3790 // Note: allocation() can be NULL, for secondary initialization barriers
3791 }
3792
3793 // Since this node is not matched, it will be processed by the
3794 // register allocator. Declare that there are no constraints
3795 // on the allocation of the RawAddress edge.
3796 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3797 // This edge should be set to top, by the set_complete. But be conservative.
3798 if (idx == InitializeNode::RawAddress)
3799 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3800 return RegMask::Empty;
3801 }
3802
3803 Node* InitializeNode::memory(uint alias_idx) {
3804 Node* mem = in(Memory);
3805 if (mem->is_MergeMem()) {
3806 return mem->as_MergeMem()->memory_at(alias_idx);
3807 } else {
3808 // incoming raw memory is not split
3809 return mem;
3810 }
3811 }
3812
3813 bool InitializeNode::is_non_zero() {
3814 if (is_complete()) return false;
3815 remove_extra_zeroes();
3816 return (req() > RawStores);
3817 }
3818
3819 void InitializeNode::set_complete(PhaseGVN* phase) {
3820 assert(!is_complete(), "caller responsibility");
3821 _is_complete = Complete;
3822
3823 // After this node is complete, it contains a bunch of
3824 // raw-memory initializations. There is no need for
3825 // it to have anything to do with non-raw memory effects.
3826 // Therefore, tell all non-raw users to re-optimize themselves,
3827 // after skipping the memory effects of this initialization.
3828 PhaseIterGVN* igvn = phase->is_IterGVN();
3829 if (igvn) igvn->add_users_to_worklist(this);
3830 }
3831
3832 // convenience function
3833 // return false if the init contains any stores already
3834 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3835 InitializeNode* init = initialization();
3836 if (init == NULL || init->is_complete()) {
3837 return false;
3838 }
3839 init->remove_extra_zeroes();
3840 // for now, if this allocation has already collected any inits, bail:
3841 if (init->is_non_zero()) return false;
3842 init->set_complete(phase);
3843 return true;
3844 }
3845
3846 void InitializeNode::remove_extra_zeroes() {
3847 if (req() == RawStores) return;
3848 Node* zmem = zero_memory();
3849 uint fill = RawStores;
3850 for (uint i = fill; i < req(); i++) {
3851 Node* n = in(i);
3852 if (n->is_top() || n == zmem) continue; // skip
3853 if (fill < i) set_req(fill, n); // compact
3854 ++fill;
3855 }
3856 // delete any empty spaces created:
3857 while (fill < req()) {
3858 del_req(fill);
3859 }
3860 }
3861
3862 // Helper for remembering which stores go with which offsets.
3863 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3864 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3865 intptr_t offset = -1;
3866 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3867 phase, offset);
3868 if (base == NULL) return -1; // something is dead,
3869 if (offset < 0) return -1; // dead, dead
3870 return offset;
3871 }
3872
3873 // Helper for proving that an initialization expression is
3874 // "simple enough" to be folded into an object initialization.
3875 // Attempts to prove that a store's initial value 'n' can be captured
3876 // within the initialization without creating a vicious cycle, such as:
3877 // { Foo p = new Foo(); p.next = p; }
3878 // True for constants and parameters and small combinations thereof.
3879 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3880 ResourceMark rm;
3881 Unique_Node_List worklist;
3882 worklist.push(value);
3883
3884 uint complexity_limit = 20;
3885 for (uint j = 0; j < worklist.size(); j++) {
3886 if (j >= complexity_limit) {
3887 return false; // Bail out if processed too many nodes
3888 }
3889
3890 Node* n = worklist.at(j);
3891 if (n == NULL) continue; // (can this really happen?)
3892 if (n->is_Proj()) n = n->in(0);
3893 if (n == this) return false; // found a cycle
3894 if (n->is_Con()) continue;
3895 if (n->is_Start()) continue; // params, etc., are OK
3896 if (n->is_Root()) continue; // even better
3897
3898 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3899 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3900 continue;
3901 }
3902
3903 Node* ctl = n->in(0);
3904 if (ctl != NULL && !ctl->is_top()) {
3905 if (ctl->is_Proj()) ctl = ctl->in(0);
3906 if (ctl == this) return false;
3907
3908 // If we already know that the enclosing memory op is pinned right after
3909 // the init, then any control flow that the store has picked up
3910 // must have preceded the init, or else be equal to the init.
3911 // Even after loop optimizations (which might change control edges)
3912 // a store is never pinned *before* the availability of its inputs.
3913 if (!MemNode::all_controls_dominate(n, this))
3914 return false; // failed to prove a good control
3915 }
3916
3917 // Check data edges for possible dependencies on 'this'.
3918 for (uint i = 1; i < n->req(); i++) {
3919 Node* m = n->in(i);
3920 if (m == NULL || m == n || m->is_top()) continue;
3921
3922 // Only process data inputs once
3923 worklist.push(m);
3924 }
3925 }
3926
3927 return true;
3928 }
3929
3930 // Here are all the checks a Store must pass before it can be moved into
3931 // an initialization. Returns zero if a check fails.
3932 // On success, returns the (constant) offset to which the store applies,
3933 // within the initialized memory.
3934 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3935 const int FAIL = 0;
3936 if (st->req() != MemNode::ValueIn + 1)
3937 return FAIL; // an inscrutable StoreNode (card mark?)
3938 Node* ctl = st->in(MemNode::Control);
3939 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3940 return FAIL; // must be unconditional after the initialization
3941 Node* mem = st->in(MemNode::Memory);
3942 if (!(mem->is_Proj() && mem->in(0) == this))
3943 return FAIL; // must not be preceded by other stores
3944 Node* adr = st->in(MemNode::Address);
3945 intptr_t offset;
3946 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3947 if (alloc == NULL)
3948 return FAIL; // inscrutable address
3949 if (alloc != allocation())
3950 return FAIL; // wrong allocation! (store needs to float up)
3951 int size_in_bytes = st->memory_size();
3952 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3953 return FAIL; // mismatched access
3954 }
3955 Node* val = st->in(MemNode::ValueIn);
3956
3957 if (!detect_init_independence(val, phase))
3958 return FAIL; // stored value must be 'simple enough'
3959
3960 // The Store can be captured only if nothing after the allocation
3961 // and before the Store is using the memory location that the store
3962 // overwrites.
3963 bool failed = false;
3964 // If is_complete_with_arraycopy() is true the shape of the graph is
3965 // well defined and is safe so no need for extra checks.
3966 if (!is_complete_with_arraycopy()) {
3967 // We are going to look at each use of the memory state following
3968 // the allocation to make sure nothing reads the memory that the
3969 // Store writes.
3970 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3971 int alias_idx = phase->C->get_alias_index(t_adr);
3972 ResourceMark rm;
3973 Unique_Node_List mems;
3974 mems.push(mem);
3975 Node* unique_merge = NULL;
3976 for (uint next = 0; next < mems.size(); ++next) {
3977 Node *m = mems.at(next);
3978 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3979 Node *n = m->fast_out(j);
3980 if (n->outcnt() == 0) {
3981 continue;
3982 }
3983 if (n == st) {
3984 continue;
3985 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3986 // If the control of this use is different from the control
3987 // of the Store which is right after the InitializeNode then
3988 // this node cannot be between the InitializeNode and the
3989 // Store.
3990 continue;
3991 } else if (n->is_MergeMem()) {
3992 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3993 // We can hit a MergeMemNode (that will likely go away
3994 // later) that is a direct use of the memory state
3995 // following the InitializeNode on the same slice as the
3996 // store node that we'd like to capture. We need to check
3997 // the uses of the MergeMemNode.
3998 mems.push(n);
3999 }
4000 } else if (n->is_Mem()) {
4001 Node* other_adr = n->in(MemNode::Address);
4002 if (other_adr == adr) {
4003 failed = true;
4004 break;
4005 } else {
4006 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
4007 if (other_t_adr != NULL) {
4008 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
4009 if (other_alias_idx == alias_idx) {
4010 // A load from the same memory slice as the store right
4011 // after the InitializeNode. We check the control of the
4012 // object/array that is loaded from. If it's the same as
4013 // the store control then we cannot capture the store.
4014 assert(!n->is_Store(), "2 stores to same slice on same control?");
4015 Node* base = other_adr;
4016 if (base->is_Phi()) {
4017 // In rare case, base may be a PhiNode and it may read
4018 // the same memory slice between InitializeNode and store.
4019 failed = true;
4020 break;
4021 }
4022 assert(base->is_AddP(), "should be addp but is %s", base->Name());
4023 base = base->in(AddPNode::Base);
4024 if (base != NULL) {
4025 base = base->uncast();
4026 if (base->is_Proj() && base->in(0) == alloc) {
4027 failed = true;
4028 break;
4029 }
4030 }
4031 }
4032 }
4033 }
4034 } else {
4035 failed = true;
4036 break;
4037 }
4038 }
4039 }
4040 }
4041 if (failed) {
4042 if (!can_reshape) {
4043 // We decided we couldn't capture the store during parsing. We
4044 // should try again during the next IGVN once the graph is
4045 // cleaner.
4046 phase->C->record_for_igvn(st);
4047 }
4048 return FAIL;
4049 }
4050
4051 return offset; // success
4052 }
4053
4054 // Find the captured store in(i) which corresponds to the range
4055 // [start..start+size) in the initialized object.
4056 // If there is one, return its index i. If there isn't, return the
4057 // negative of the index where it should be inserted.
4058 // Return 0 if the queried range overlaps an initialization boundary
4059 // or if dead code is encountered.
4060 // If size_in_bytes is zero, do not bother with overlap checks.
4061 int InitializeNode::captured_store_insertion_point(intptr_t start,
4062 int size_in_bytes,
4063 PhaseTransform* phase) {
4064 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
4065
4066 if (is_complete())
4067 return FAIL; // arraycopy got here first; punt
4068
4069 assert(allocation() != NULL, "must be present");
4070
4071 // no negatives, no header fields:
4072 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
4073
4074 // after a certain size, we bail out on tracking all the stores:
4075 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4076 if (start >= ti_limit) return FAIL;
4077
4078 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4079 if (i >= limit) return -(int)i; // not found; here is where to put it
4080
4081 Node* st = in(i);
4082 intptr_t st_off = get_store_offset(st, phase);
4083 if (st_off < 0) {
4084 if (st != zero_memory()) {
4085 return FAIL; // bail out if there is dead garbage
4086 }
4087 } else if (st_off > start) {
4088 // ...we are done, since stores are ordered
4089 if (st_off < start + size_in_bytes) {
4090 return FAIL; // the next store overlaps
4091 }
4092 return -(int)i; // not found; here is where to put it
4093 } else if (st_off < start) {
4094 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4095 if (size_in_bytes != 0 &&
4096 start < st_off + MAX_STORE &&
4097 start < st_off + st->as_Store()->memory_size()) {
4098 return FAIL; // the previous store overlaps
4099 }
4100 } else {
4101 if (size_in_bytes != 0 &&
4102 st->as_Store()->memory_size() != size_in_bytes) {
4103 return FAIL; // mismatched store size
4104 }
4105 return i;
4106 }
4107
4108 ++i;
4109 }
4110 }
4111
4112 // Look for a captured store which initializes at the offset 'start'
4113 // with the given size. If there is no such store, and no other
4114 // initialization interferes, then return zero_memory (the memory
4115 // projection of the AllocateNode).
4116 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4117 PhaseTransform* phase) {
4118 assert(stores_are_sane(phase), "");
4119 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4120 if (i == 0) {
4121 return NULL; // something is dead
4122 } else if (i < 0) {
4123 return zero_memory(); // just primordial zero bits here
4124 } else {
4125 Node* st = in(i); // here is the store at this position
4126 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4127 return st;
4128 }
4129 }
4130
4131 // Create, as a raw pointer, an address within my new object at 'offset'.
4132 Node* InitializeNode::make_raw_address(intptr_t offset,
4133 PhaseTransform* phase) {
4134 Node* addr = in(RawAddress);
4135 if (offset != 0) {
4136 Compile* C = phase->C;
4137 addr = phase->transform( new AddPNode(C->top(), addr,
4138 phase->MakeConX(offset)) );
4139 }
4140 return addr;
4141 }
4142
4143 // Clone the given store, converting it into a raw store
4144 // initializing a field or element of my new object.
4145 // Caller is responsible for retiring the original store,
4146 // with subsume_node or the like.
4147 //
4148 // From the example above InitializeNode::InitializeNode,
4149 // here are the old stores to be captured:
4150 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4151 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4152 //
4153 // Here is the changed code; note the extra edges on init:
4154 // alloc = (Allocate ...)
4155 // rawoop = alloc.RawAddress
4156 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4157 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4158 // init = (Initialize alloc.Control alloc.Memory rawoop
4159 // rawstore1 rawstore2)
4160 //
4161 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4162 PhaseGVN* phase, bool can_reshape) {
4163 assert(stores_are_sane(phase), "");
4164
4165 if (start < 0) return NULL;
4166 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4167
4168 Compile* C = phase->C;
4169 int size_in_bytes = st->memory_size();
4170 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4171 if (i == 0) return NULL; // bail out
4172 Node* prev_mem = NULL; // raw memory for the captured store
4173 if (i > 0) {
4174 prev_mem = in(i); // there is a pre-existing store under this one
4175 set_req(i, C->top()); // temporarily disconnect it
4176 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4177 } else {
4178 i = -i; // no pre-existing store
4179 prev_mem = zero_memory(); // a slice of the newly allocated object
4180 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4181 set_req(--i, C->top()); // reuse this edge; it has been folded away
4182 else
4183 ins_req(i, C->top()); // build a new edge
4184 }
4185 Node* new_st = st->clone();
4186 new_st->set_req(MemNode::Control, in(Control));
4187 new_st->set_req(MemNode::Memory, prev_mem);
4188 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4189 new_st = phase->transform(new_st);
4190
4191 // At this point, new_st might have swallowed a pre-existing store
4192 // at the same offset, or perhaps new_st might have disappeared,
4193 // if it redundantly stored the same value (or zero to fresh memory).
4194
4195 // In any case, wire it in:
4196 PhaseIterGVN* igvn = phase->is_IterGVN();
4197 if (igvn) {
4198 igvn->rehash_node_delayed(this);
4199 }
4200 set_req(i, new_st);
4201
4202 // The caller may now kill the old guy.
4203 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4204 assert(check_st == new_st || check_st == NULL, "must be findable");
4205 assert(!is_complete(), "");
4206 return new_st;
4207 }
4208
4209 static bool store_constant(jlong* tiles, int num_tiles,
4210 intptr_t st_off, int st_size,
4211 jlong con) {
4212 if ((st_off & (st_size-1)) != 0)
4213 return false; // strange store offset (assume size==2**N)
4214 address addr = (address)tiles + st_off;
4215 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4216 switch (st_size) {
4217 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4218 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4219 case sizeof(jint): *(jint*) addr = (jint) con; break;
4220 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4221 default: return false; // strange store size (detect size!=2**N here)
4222 }
4223 return true; // return success to caller
4224 }
4225
4226 // Coalesce subword constants into int constants and possibly
4227 // into long constants. The goal, if the CPU permits,
4228 // is to initialize the object with a small number of 64-bit tiles.
4229 // Also, convert floating-point constants to bit patterns.
4230 // Non-constants are not relevant to this pass.
4231 //
4232 // In terms of the running example on InitializeNode::InitializeNode
4233 // and InitializeNode::capture_store, here is the transformation
4234 // of rawstore1 and rawstore2 into rawstore12:
4235 // alloc = (Allocate ...)
4236 // rawoop = alloc.RawAddress
4237 // tile12 = 0x00010002
4238 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4239 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4240 //
4241 void
4242 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4243 Node* size_in_bytes,
4244 PhaseGVN* phase) {
4245 Compile* C = phase->C;
4246
4247 assert(stores_are_sane(phase), "");
4248 // Note: After this pass, they are not completely sane,
4249 // since there may be some overlaps.
4250
4251 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4252
4253 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4254 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4255 size_limit = MIN2(size_limit, ti_limit);
4256 size_limit = align_up(size_limit, BytesPerLong);
4257 int num_tiles = size_limit / BytesPerLong;
4258
4259 // allocate space for the tile map:
4260 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4261 jlong tiles_buf[small_len];
4262 Node* nodes_buf[small_len];
4263 jlong inits_buf[small_len];
4264 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4265 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4266 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4267 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4268 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4269 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4270 // tiles: exact bitwise model of all primitive constants
4271 // nodes: last constant-storing node subsumed into the tiles model
4272 // inits: which bytes (in each tile) are touched by any initializations
4273
4274 //// Pass A: Fill in the tile model with any relevant stores.
4275
4276 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4277 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4278 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4279 Node* zmem = zero_memory(); // initially zero memory state
4280 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4281 Node* st = in(i);
4282 intptr_t st_off = get_store_offset(st, phase);
4283
4284 // Figure out the store's offset and constant value:
4285 if (st_off < header_size) continue; //skip (ignore header)
4286 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4287 int st_size = st->as_Store()->memory_size();
4288 if (st_off + st_size > size_limit) break;
4289
4290 // Record which bytes are touched, whether by constant or not.
4291 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4292 continue; // skip (strange store size)
4293
4294 const Type* val = phase->type(st->in(MemNode::ValueIn));
4295 if (!val->singleton()) continue; //skip (non-con store)
4296 BasicType type = val->basic_type();
4297
4298 jlong con = 0;
4299 switch (type) {
4300 case T_INT: con = val->is_int()->get_con(); break;
4301 case T_LONG: con = val->is_long()->get_con(); break;
4302 case T_FLOAT: con = jint_cast(val->getf()); break;
4303 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4304 default: continue; //skip (odd store type)
4305 }
4306
4307 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4308 st->Opcode() == Op_StoreL) {
4309 continue; // This StoreL is already optimal.
4310 }
4311
4312 // Store down the constant.
4313 store_constant(tiles, num_tiles, st_off, st_size, con);
4314
4315 intptr_t j = st_off >> LogBytesPerLong;
4316
4317 if (type == T_INT && st_size == BytesPerInt
4318 && (st_off & BytesPerInt) == BytesPerInt) {
4319 jlong lcon = tiles[j];
4320 if (!Matcher::isSimpleConstant64(lcon) &&
4321 st->Opcode() == Op_StoreI) {
4322 // This StoreI is already optimal by itself.
4323 jint* intcon = (jint*) &tiles[j];
4324 intcon[1] = 0; // undo the store_constant()
4325
4326 // If the previous store is also optimal by itself, back up and
4327 // undo the action of the previous loop iteration... if we can.
4328 // But if we can't, just let the previous half take care of itself.
4329 st = nodes[j];
4330 st_off -= BytesPerInt;
4331 con = intcon[0];
4332 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4333 assert(st_off >= header_size, "still ignoring header");
4334 assert(get_store_offset(st, phase) == st_off, "must be");
4335 assert(in(i-1) == zmem, "must be");
4336 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4337 assert(con == tcon->is_int()->get_con(), "must be");
4338 // Undo the effects of the previous loop trip, which swallowed st:
4339 intcon[0] = 0; // undo store_constant()
4340 set_req(i-1, st); // undo set_req(i, zmem)
4341 nodes[j] = NULL; // undo nodes[j] = st
4342 --old_subword; // undo ++old_subword
4343 }
4344 continue; // This StoreI is already optimal.
4345 }
4346 }
4347
4348 // This store is not needed.
4349 set_req(i, zmem);
4350 nodes[j] = st; // record for the moment
4351 if (st_size < BytesPerLong) // something has changed
4352 ++old_subword; // includes int/float, but who's counting...
4353 else ++old_long;
4354 }
4355
4356 if ((old_subword + old_long) == 0)
4357 return; // nothing more to do
4358
4359 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4360 // Be sure to insert them before overlapping non-constant stores.
4361 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4362 for (int j = 0; j < num_tiles; j++) {
4363 jlong con = tiles[j];
4364 jlong init = inits[j];
4365 if (con == 0) continue;
4366 jint con0, con1; // split the constant, address-wise
4367 jint init0, init1; // split the init map, address-wise
4368 { union { jlong con; jint intcon[2]; } u;
4369 u.con = con;
4370 con0 = u.intcon[0];
4371 con1 = u.intcon[1];
4372 u.con = init;
4373 init0 = u.intcon[0];
4374 init1 = u.intcon[1];
4375 }
4376
4377 Node* old = nodes[j];
4378 assert(old != NULL, "need the prior store");
4379 intptr_t offset = (j * BytesPerLong);
4380
4381 bool split = !Matcher::isSimpleConstant64(con);
4382
4383 if (offset < header_size) {
4384 assert(offset + BytesPerInt >= header_size, "second int counts");
4385 assert(*(jint*)&tiles[j] == 0, "junk in header");
4386 split = true; // only the second word counts
4387 // Example: int a[] = { 42 ... }
4388 } else if (con0 == 0 && init0 == -1) {
4389 split = true; // first word is covered by full inits
4390 // Example: int a[] = { ... foo(), 42 ... }
4391 } else if (con1 == 0 && init1 == -1) {
4392 split = true; // second word is covered by full inits
4393 // Example: int a[] = { ... 42, foo() ... }
4394 }
4395
4396 // Here's a case where init0 is neither 0 nor -1:
4397 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4398 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4399 // In this case the tile is not split; it is (jlong)42.
4400 // The big tile is stored down, and then the foo() value is inserted.
4401 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4402
4403 Node* ctl = old->in(MemNode::Control);
4404 Node* adr = make_raw_address(offset, phase);
4405 const TypePtr* atp = TypeRawPtr::BOTTOM;
4406
4407 // One or two coalesced stores to plop down.
4408 Node* st[2];
4409 intptr_t off[2];
4410 int nst = 0;
4411 if (!split) {
4412 ++new_long;
4413 off[nst] = offset;
4414 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4415 phase->longcon(con), T_LONG, MemNode::unordered);
4416 } else {
4417 // Omit either if it is a zero.
4418 if (con0 != 0) {
4419 ++new_int;
4420 off[nst] = offset;
4421 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4422 phase->intcon(con0), T_INT, MemNode::unordered);
4423 }
4424 if (con1 != 0) {
4425 ++new_int;
4426 offset += BytesPerInt;
4427 adr = make_raw_address(offset, phase);
4428 off[nst] = offset;
4429 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4430 phase->intcon(con1), T_INT, MemNode::unordered);
4431 }
4432 }
4433
4434 // Insert second store first, then the first before the second.
4435 // Insert each one just before any overlapping non-constant stores.
4436 while (nst > 0) {
4437 Node* st1 = st[--nst];
4438 C->copy_node_notes_to(st1, old);
4439 st1 = phase->transform(st1);
4440 offset = off[nst];
4441 assert(offset >= header_size, "do not smash header");
4442 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4443 guarantee(ins_idx != 0, "must re-insert constant store");
4444 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4445 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4446 set_req(--ins_idx, st1);
4447 else
4448 ins_req(ins_idx, st1);
4449 }
4450 }
4451
4452 if (PrintCompilation && WizardMode)
4453 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4454 old_subword, old_long, new_int, new_long);
4455 if (C->log() != NULL)
4456 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4457 old_subword, old_long, new_int, new_long);
4458
4459 // Clean up any remaining occurrences of zmem:
4460 remove_extra_zeroes();
4461 }
4462
4463 // Explore forward from in(start) to find the first fully initialized
4464 // word, and return its offset. Skip groups of subword stores which
4465 // together initialize full words. If in(start) is itself part of a
4466 // fully initialized word, return the offset of in(start). If there
4467 // are no following full-word stores, or if something is fishy, return
4468 // a negative value.
4469 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4470 int int_map = 0;
4471 intptr_t int_map_off = 0;
4472 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4473
4474 for (uint i = start, limit = req(); i < limit; i++) {
4475 Node* st = in(i);
4476
4477 intptr_t st_off = get_store_offset(st, phase);
4478 if (st_off < 0) break; // return conservative answer
4479
4480 int st_size = st->as_Store()->memory_size();
4481 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4482 return st_off; // we found a complete word init
4483 }
4484
4485 // update the map:
4486
4487 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4488 if (this_int_off != int_map_off) {
4489 // reset the map:
4490 int_map = 0;
4491 int_map_off = this_int_off;
4492 }
4493
4494 int subword_off = st_off - this_int_off;
4495 int_map |= right_n_bits(st_size) << subword_off;
4496 if ((int_map & FULL_MAP) == FULL_MAP) {
4497 return this_int_off; // we found a complete word init
4498 }
4499
4500 // Did this store hit or cross the word boundary?
4501 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4502 if (next_int_off == this_int_off + BytesPerInt) {
4503 // We passed the current int, without fully initializing it.
4504 int_map_off = next_int_off;
4505 int_map >>= BytesPerInt;
4506 } else if (next_int_off > this_int_off + BytesPerInt) {
4507 // We passed the current and next int.
4508 return this_int_off + BytesPerInt;
4509 }
4510 }
4511
4512 return -1;
4513 }
4514
4515
4516 // Called when the associated AllocateNode is expanded into CFG.
4517 // At this point, we may perform additional optimizations.
4518 // Linearize the stores by ascending offset, to make memory
4519 // activity as coherent as possible.
4520 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4521 intptr_t header_size,
4522 Node* size_in_bytes,
4523 PhaseIterGVN* phase) {
4524 assert(!is_complete(), "not already complete");
4525 assert(stores_are_sane(phase), "");
4526 assert(allocation() != NULL, "must be present");
4527
4528 remove_extra_zeroes();
4529
4530 if (ReduceFieldZeroing || ReduceBulkZeroing)
4531 // reduce instruction count for common initialization patterns
4532 coalesce_subword_stores(header_size, size_in_bytes, phase);
4533
4534 Node* zmem = zero_memory(); // initially zero memory state
4535 Node* inits = zmem; // accumulating a linearized chain of inits
4536 #ifdef ASSERT
4537 intptr_t first_offset = allocation()->minimum_header_size();
4538 intptr_t last_init_off = first_offset; // previous init offset
4539 intptr_t last_init_end = first_offset; // previous init offset+size
4540 intptr_t last_tile_end = first_offset; // previous tile offset+size
4541 #endif
4542 intptr_t zeroes_done = header_size;
4543
4544 bool do_zeroing = true; // we might give up if inits are very sparse
4545 int big_init_gaps = 0; // how many large gaps have we seen?
4546
4547 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4548 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4549
4550 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4551 Node* st = in(i);
4552 intptr_t st_off = get_store_offset(st, phase);
4553 if (st_off < 0)
4554 break; // unknown junk in the inits
4555 if (st->in(MemNode::Memory) != zmem)
4556 break; // complicated store chains somehow in list
4557
4558 int st_size = st->as_Store()->memory_size();
4559 intptr_t next_init_off = st_off + st_size;
4560
4561 if (do_zeroing && zeroes_done < next_init_off) {
4562 // See if this store needs a zero before it or under it.
4563 intptr_t zeroes_needed = st_off;
4564
4565 if (st_size < BytesPerInt) {
4566 // Look for subword stores which only partially initialize words.
4567 // If we find some, we must lay down some word-level zeroes first,
4568 // underneath the subword stores.
4569 //
4570 // Examples:
4571 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4572 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4573 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4574 //
4575 // Note: coalesce_subword_stores may have already done this,
4576 // if it was prompted by constant non-zero subword initializers.
4577 // But this case can still arise with non-constant stores.
4578
4579 intptr_t next_full_store = find_next_fullword_store(i, phase);
4580
4581 // In the examples above:
4582 // in(i) p q r s x y z
4583 // st_off 12 13 14 15 12 13 14
4584 // st_size 1 1 1 1 1 1 1
4585 // next_full_s. 12 16 16 16 16 16 16
4586 // z's_done 12 16 16 16 12 16 12
4587 // z's_needed 12 16 16 16 16 16 16
4588 // zsize 0 0 0 0 4 0 4
4589 if (next_full_store < 0) {
4590 // Conservative tack: Zero to end of current word.
4591 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4592 } else {
4593 // Zero to beginning of next fully initialized word.
4594 // Or, don't zero at all, if we are already in that word.
4595 assert(next_full_store >= zeroes_needed, "must go forward");
4596 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4597 zeroes_needed = next_full_store;
4598 }
4599 }
4600
4601 if (zeroes_needed > zeroes_done) {
4602 intptr_t zsize = zeroes_needed - zeroes_done;
4603 // Do some incremental zeroing on rawmem, in parallel with inits.
4604 zeroes_done = align_down(zeroes_done, BytesPerInt);
4605 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4606 allocation()->in(AllocateNode::DefaultValue),
4607 allocation()->in(AllocateNode::RawDefaultValue),
4608 zeroes_done, zeroes_needed,
4609 phase);
4610 zeroes_done = zeroes_needed;
4611 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4612 do_zeroing = false; // leave the hole, next time
4613 }
4614 }
4615
4616 // Collect the store and move on:
4617 phase->replace_input_of(st, MemNode::Memory, inits);
4618 inits = st; // put it on the linearized chain
4619 set_req(i, zmem); // unhook from previous position
4620
4621 if (zeroes_done == st_off)
4622 zeroes_done = next_init_off;
4623
4624 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4625
4626 #ifdef ASSERT
4627 // Various order invariants. Weaker than stores_are_sane because
4628 // a large constant tile can be filled in by smaller non-constant stores.
4629 assert(st_off >= last_init_off, "inits do not reverse");
4630 last_init_off = st_off;
4631 const Type* val = NULL;
4632 if (st_size >= BytesPerInt &&
4633 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4634 (int)val->basic_type() < (int)T_OBJECT) {
4635 assert(st_off >= last_tile_end, "tiles do not overlap");
4636 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4637 last_tile_end = MAX2(last_tile_end, next_init_off);
4638 } else {
4639 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4640 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4641 assert(st_off >= last_init_end, "inits do not overlap");
4642 last_init_end = next_init_off; // it's a non-tile
4643 }
4644 #endif //ASSERT
4645 }
4646
4647 remove_extra_zeroes(); // clear out all the zmems left over
4648 add_req(inits);
4649
4650 if (!(UseTLAB && ZeroTLAB)) {
4651 // If anything remains to be zeroed, zero it all now.
4652 zeroes_done = align_down(zeroes_done, BytesPerInt);
4653 // if it is the last unused 4 bytes of an instance, forget about it
4654 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4655 if (zeroes_done + BytesPerLong >= size_limit) {
4656 AllocateNode* alloc = allocation();
4657 assert(alloc != NULL, "must be present");
4658 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4659 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4660 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
4661 if (zeroes_done == k->layout_helper())
4662 zeroes_done = size_limit;
4663 }
4664 }
4665 if (zeroes_done < size_limit) {
4666 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4667 allocation()->in(AllocateNode::DefaultValue),
4668 allocation()->in(AllocateNode::RawDefaultValue),
4669 zeroes_done, size_in_bytes, phase);
4670 }
4671 }
4672
4673 set_complete(phase);
4674 return rawmem;
4675 }
4676
4677
4678 #ifdef ASSERT
4679 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4680 if (is_complete())
4681 return true; // stores could be anything at this point
4682 assert(allocation() != NULL, "must be present");
4683 intptr_t last_off = allocation()->minimum_header_size();
4684 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4685 Node* st = in(i);
4686 intptr_t st_off = get_store_offset(st, phase);
4687 if (st_off < 0) continue; // ignore dead garbage
4688 if (last_off > st_off) {
4689 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4690 this->dump(2);
4691 assert(false, "ascending store offsets");
4692 return false;
4693 }
4694 last_off = st_off + st->as_Store()->memory_size();
4695 }
4696 return true;
4697 }
4698 #endif //ASSERT
4699
4700
4701
4702
4703 //============================MergeMemNode=====================================
4704 //
4705 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4706 // contributing store or call operations. Each contributor provides the memory
4707 // state for a particular "alias type" (see Compile::alias_type). For example,
4708 // if a MergeMem has an input X for alias category #6, then any memory reference
4709 // to alias category #6 may use X as its memory state input, as an exact equivalent
4710 // to using the MergeMem as a whole.
4711 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4712 //
4713 // (Here, the <N> notation gives the index of the relevant adr_type.)
4714 //
4715 // In one special case (and more cases in the future), alias categories overlap.
4716 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4717 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4718 // it is exactly equivalent to that state W:
4719 // MergeMem(<Bot>: W) <==> W
4720 //
4721 // Usually, the merge has more than one input. In that case, where inputs
4722 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4723 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4724 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4725 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4726 //
4727 // A merge can take a "wide" memory state as one of its narrow inputs.
4728 // This simply means that the merge observes out only the relevant parts of
4729 // the wide input. That is, wide memory states arriving at narrow merge inputs
4730 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4731 //
4732 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4733 // and that memory slices "leak through":
4734 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4735 //
4736 // But, in such a cascade, repeated memory slices can "block the leak":
4737 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4738 //
4739 // In the last example, Y is not part of the combined memory state of the
4740 // outermost MergeMem. The system must, of course, prevent unschedulable
4741 // memory states from arising, so you can be sure that the state Y is somehow
4742 // a precursor to state Y'.
4743 //
4744 //
4745 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4746 // of each MergeMemNode array are exactly the numerical alias indexes, including
4747 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4748 // Compile::alias_type (and kin) produce and manage these indexes.
4749 //
4750 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4751 // (Note that this provides quick access to the top node inside MergeMem methods,
4752 // without the need to reach out via TLS to Compile::current.)
4753 //
4754 // As a consequence of what was just described, a MergeMem that represents a full
4755 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4756 // containing all alias categories.
4757 //
4758 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4759 //
4760 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4761 // a memory state for the alias type <N>, or else the top node, meaning that
4762 // there is no particular input for that alias type. Note that the length of
4763 // a MergeMem is variable, and may be extended at any time to accommodate new
4764 // memory states at larger alias indexes. When merges grow, they are of course
4765 // filled with "top" in the unused in() positions.
4766 //
4767 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4768 // (Top was chosen because it works smoothly with passes like GCM.)
4769 //
4770 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4771 // the type of random VM bits like TLS references.) Since it is always the
4772 // first non-Bot memory slice, some low-level loops use it to initialize an
4773 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4774 //
4775 //
4776 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4777 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4778 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4779 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4780 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4781 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4782 //
4783 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4784 // really that different from the other memory inputs. An abbreviation called
4785 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4786 //
4787 //
4788 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4789 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4790 // that "emerges though" the base memory will be marked as excluding the alias types
4791 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4792 //
4793 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4794 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4795 //
4796 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4797 // (It is currently unimplemented.) As you can see, the resulting merge is
4798 // actually a disjoint union of memory states, rather than an overlay.
4799 //
4800
4801 //------------------------------MergeMemNode-----------------------------------
4802 Node* MergeMemNode::make_empty_memory() {
4803 Node* empty_memory = (Node*) Compile::current()->top();
4804 assert(empty_memory->is_top(), "correct sentinel identity");
4805 return empty_memory;
4806 }
4807
4808 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4809 init_class_id(Class_MergeMem);
4810 // all inputs are nullified in Node::Node(int)
4811 // set_input(0, NULL); // no control input
4812
4813 // Initialize the edges uniformly to top, for starters.
4814 Node* empty_mem = make_empty_memory();
4815 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4816 init_req(i,empty_mem);
4817 }
4818 assert(empty_memory() == empty_mem, "");
4819
4820 if( new_base != NULL && new_base->is_MergeMem() ) {
4821 MergeMemNode* mdef = new_base->as_MergeMem();
4822 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4823 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4824 mms.set_memory(mms.memory2());
4825 }
4826 assert(base_memory() == mdef->base_memory(), "");
4827 } else {
4828 set_base_memory(new_base);
4829 }
4830 }
4831
4832 // Make a new, untransformed MergeMem with the same base as 'mem'.
4833 // If mem is itself a MergeMem, populate the result with the same edges.
4834 MergeMemNode* MergeMemNode::make(Node* mem) {
4835 return new MergeMemNode(mem);
4836 }
4837
4838 //------------------------------cmp--------------------------------------------
4839 uint MergeMemNode::hash() const { return NO_HASH; }
4840 bool MergeMemNode::cmp( const Node &n ) const {
4841 return (&n == this); // Always fail except on self
4842 }
4843
4844 //------------------------------Identity---------------------------------------
4845 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4846 // Identity if this merge point does not record any interesting memory
4847 // disambiguations.
4848 Node* base_mem = base_memory();
4849 Node* empty_mem = empty_memory();
4850 if (base_mem != empty_mem) { // Memory path is not dead?
4851 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4852 Node* mem = in(i);
4853 if (mem != empty_mem && mem != base_mem) {
4854 return this; // Many memory splits; no change
4855 }
4856 }
4857 }
4858 return base_mem; // No memory splits; ID on the one true input
4859 }
4860
4861 //------------------------------Ideal------------------------------------------
4862 // This method is invoked recursively on chains of MergeMem nodes
4863 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4864 // Remove chain'd MergeMems
4865 //
4866 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4867 // relative to the "in(Bot)". Since we are patching both at the same time,
4868 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4869 // but rewrite each "in(i)" relative to the new "in(Bot)".
4870 Node *progress = NULL;
4871
4872
4873 Node* old_base = base_memory();
4874 Node* empty_mem = empty_memory();
4875 if (old_base == empty_mem)
4876 return NULL; // Dead memory path.
4877
4878 MergeMemNode* old_mbase;
4879 if (old_base != NULL && old_base->is_MergeMem())
4880 old_mbase = old_base->as_MergeMem();
4881 else
4882 old_mbase = NULL;
4883 Node* new_base = old_base;
4884
4885 // simplify stacked MergeMems in base memory
4886 if (old_mbase) new_base = old_mbase->base_memory();
4887
4888 // the base memory might contribute new slices beyond my req()
4889 if (old_mbase) grow_to_match(old_mbase);
4890
4891 // Note: We do not call verify_sparse on entry, because inputs
4892 // can normalize to the base_memory via subsume_node or similar
4893 // mechanisms. This method repairs that damage.
4894
4895 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4896
4897 // Look at each slice.
4898 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4899 Node* old_in = in(i);
4900 // calculate the old memory value
4901 Node* old_mem = old_in;
4902 if (old_mem == empty_mem) old_mem = old_base;
4903 assert(old_mem == memory_at(i), "");
4904
4905 // maybe update (reslice) the old memory value
4906
4907 // simplify stacked MergeMems
4908 Node* new_mem = old_mem;
4909 MergeMemNode* old_mmem;
4910 if (old_mem != NULL && old_mem->is_MergeMem())
4911 old_mmem = old_mem->as_MergeMem();
4912 else
4913 old_mmem = NULL;
4914 if (old_mmem == this) {
4915 // This can happen if loops break up and safepoints disappear.
4916 // A merge of BotPtr (default) with a RawPtr memory derived from a
4917 // safepoint can be rewritten to a merge of the same BotPtr with
4918 // the BotPtr phi coming into the loop. If that phi disappears
4919 // also, we can end up with a self-loop of the mergemem.
4920 // In general, if loops degenerate and memory effects disappear,
4921 // a mergemem can be left looking at itself. This simply means
4922 // that the mergemem's default should be used, since there is
4923 // no longer any apparent effect on this slice.
4924 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4925 // from start. Update the input to TOP.
4926 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4927 }
4928 else if (old_mmem != NULL) {
4929 new_mem = old_mmem->memory_at(i);
4930 }
4931 // else preceding memory was not a MergeMem
4932
4933 // maybe store down a new value
4934 Node* new_in = new_mem;
4935 if (new_in == new_base) new_in = empty_mem;
4936
4937 if (new_in != old_in) {
4938 // Warning: Do not combine this "if" with the previous "if"
4939 // A memory slice might have be be rewritten even if it is semantically
4940 // unchanged, if the base_memory value has changed.
4941 set_req_X(i, new_in, phase);
4942 progress = this; // Report progress
4943 }
4944 }
4945
4946 if (new_base != old_base) {
4947 set_req_X(Compile::AliasIdxBot, new_base, phase);
4948 // Don't use set_base_memory(new_base), because we need to update du.
4949 assert(base_memory() == new_base, "");
4950 progress = this;
4951 }
4952
4953 if( base_memory() == this ) {
4954 // a self cycle indicates this memory path is dead
4955 set_req(Compile::AliasIdxBot, empty_mem);
4956 }
4957
4958 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4959 // Recursion must occur after the self cycle check above
4960 if( base_memory()->is_MergeMem() ) {
4961 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4962 Node *m = phase->transform(new_mbase); // Rollup any cycles
4963 if( m != NULL &&
4964 (m->is_top() ||
4965 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4966 // propagate rollup of dead cycle to self
4967 set_req(Compile::AliasIdxBot, empty_mem);
4968 }
4969 }
4970
4971 if( base_memory() == empty_mem ) {
4972 progress = this;
4973 // Cut inputs during Parse phase only.
4974 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4975 if( !can_reshape ) {
4976 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4977 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4978 }
4979 }
4980 }
4981
4982 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4983 // Check if PhiNode::Ideal's "Split phis through memory merges"
4984 // transform should be attempted. Look for this->phi->this cycle.
4985 uint merge_width = req();
4986 if (merge_width > Compile::AliasIdxRaw) {
4987 PhiNode* phi = base_memory()->as_Phi();
4988 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4989 if (phi->in(i) == this) {
4990 phase->is_IterGVN()->_worklist.push(phi);
4991 break;
4992 }
4993 }
4994 }
4995 }
4996
4997 assert(progress || verify_sparse(), "please, no dups of base");
4998 return progress;
4999 }
5000
5001 //-------------------------set_base_memory-------------------------------------
5002 void MergeMemNode::set_base_memory(Node *new_base) {
5003 Node* empty_mem = empty_memory();
5004 set_req(Compile::AliasIdxBot, new_base);
5005 assert(memory_at(req()) == new_base, "must set default memory");
5006 // Clear out other occurrences of new_base:
5007 if (new_base != empty_mem) {
5008 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5009 if (in(i) == new_base) set_req(i, empty_mem);
5010 }
5011 }
5012 }
5013
5014 //------------------------------out_RegMask------------------------------------
5015 const RegMask &MergeMemNode::out_RegMask() const {
5016 return RegMask::Empty;
5017 }
5018
5019 //------------------------------dump_spec--------------------------------------
5020 #ifndef PRODUCT
5021 void MergeMemNode::dump_spec(outputStream *st) const {
5022 st->print(" {");
5023 Node* base_mem = base_memory();
5024 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
5025 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
5026 if (mem == base_mem) { st->print(" -"); continue; }
5027 st->print( " N%d:", mem->_idx );
5028 Compile::current()->get_adr_type(i)->dump_on(st);
5029 }
5030 st->print(" }");
5031 }
5032 #endif // !PRODUCT
5033
5034
5035 #ifdef ASSERT
5036 static bool might_be_same(Node* a, Node* b) {
5037 if (a == b) return true;
5038 if (!(a->is_Phi() || b->is_Phi())) return false;
5039 // phis shift around during optimization
5040 return true; // pretty stupid...
5041 }
5042
5043 // verify a narrow slice (either incoming or outgoing)
5044 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
5045 if (!VerifyAliases) return; // don't bother to verify unless requested
5046 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
5047 if (Node::in_dump()) return; // muzzle asserts when printing
5048 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
5049 assert(n != NULL, "");
5050 // Elide intervening MergeMem's
5051 while (n->is_MergeMem()) {
5052 n = n->as_MergeMem()->memory_at(alias_idx);
5053 }
5054 Compile* C = Compile::current();
5055 const TypePtr* n_adr_type = n->adr_type();
5056 if (n == m->empty_memory()) {
5057 // Implicit copy of base_memory()
5058 } else if (n_adr_type != TypePtr::BOTTOM) {
5059 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
5060 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
5061 } else {
5062 // A few places like make_runtime_call "know" that VM calls are narrow,
5063 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
5064 bool expected_wide_mem = false;
5065 if (n == m->base_memory()) {
5066 expected_wide_mem = true;
5067 } else if (alias_idx == Compile::AliasIdxRaw ||
5068 n == m->memory_at(Compile::AliasIdxRaw)) {
5069 expected_wide_mem = true;
5070 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5071 // memory can "leak through" calls on channels that
5072 // are write-once. Allow this also.
5073 expected_wide_mem = true;
5074 }
5075 assert(expected_wide_mem, "expected narrow slice replacement");
5076 }
5077 }
5078 #else // !ASSERT
5079 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
5080 #endif
5081
5082
5083 //-----------------------------memory_at---------------------------------------
5084 Node* MergeMemNode::memory_at(uint alias_idx) const {
5085 assert(alias_idx >= Compile::AliasIdxRaw ||
5086 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
5087 "must avoid base_memory and AliasIdxTop");
5088
5089 // Otherwise, it is a narrow slice.
5090 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5091 if (is_empty_memory(n)) {
5092 // the array is sparse; empty slots are the "top" node
5093 n = base_memory();
5094 assert(Node::in_dump()
5095 || n == NULL || n->bottom_type() == Type::TOP
5096 || n->adr_type() == NULL // address is TOP
5097 || n->adr_type() == TypePtr::BOTTOM
5098 || n->adr_type() == TypeRawPtr::BOTTOM
5099 || Compile::current()->AliasLevel() == 0,
5100 "must be a wide memory");
5101 // AliasLevel == 0 if we are organizing the memory states manually.
5102 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5103 } else {
5104 // make sure the stored slice is sane
5105 #ifdef ASSERT
5106 if (VMError::is_error_reported() || Node::in_dump()) {
5107 } else if (might_be_same(n, base_memory())) {
5108 // Give it a pass: It is a mostly harmless repetition of the base.
5109 // This can arise normally from node subsumption during optimization.
5110 } else {
5111 verify_memory_slice(this, alias_idx, n);
5112 }
5113 #endif
5114 }
5115 return n;
5116 }
5117
5118 //---------------------------set_memory_at-------------------------------------
5119 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5120 verify_memory_slice(this, alias_idx, n);
5121 Node* empty_mem = empty_memory();
5122 if (n == base_memory()) n = empty_mem; // collapse default
5123 uint need_req = alias_idx+1;
5124 if (req() < need_req) {
5125 if (n == empty_mem) return; // already the default, so do not grow me
5126 // grow the sparse array
5127 do {
5128 add_req(empty_mem);
5129 } while (req() < need_req);
5130 }
5131 set_req( alias_idx, n );
5132 }
5133
5134
5135
5136 //--------------------------iteration_setup------------------------------------
5137 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5138 if (other != NULL) {
5139 grow_to_match(other);
5140 // invariant: the finite support of mm2 is within mm->req()
5141 #ifdef ASSERT
5142 for (uint i = req(); i < other->req(); i++) {
5143 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5144 }
5145 #endif
5146 }
5147 // Replace spurious copies of base_memory by top.
5148 Node* base_mem = base_memory();
5149 if (base_mem != NULL && !base_mem->is_top()) {
5150 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5151 if (in(i) == base_mem)
5152 set_req(i, empty_memory());
5153 }
5154 }
5155 }
5156
5157 //---------------------------grow_to_match-------------------------------------
5158 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5159 Node* empty_mem = empty_memory();
5160 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5161 // look for the finite support of the other memory
5162 for (uint i = other->req(); --i >= req(); ) {
5163 if (other->in(i) != empty_mem) {
5164 uint new_len = i+1;
5165 while (req() < new_len) add_req(empty_mem);
5166 break;
5167 }
5168 }
5169 }
5170
5171 //---------------------------verify_sparse-------------------------------------
5172 #ifndef PRODUCT
5173 bool MergeMemNode::verify_sparse() const {
5174 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5175 Node* base_mem = base_memory();
5176 // The following can happen in degenerate cases, since empty==top.
5177 if (is_empty_memory(base_mem)) return true;
5178 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5179 assert(in(i) != NULL, "sane slice");
5180 if (in(i) == base_mem) return false; // should have been the sentinel value!
5181 }
5182 return true;
5183 }
5184
5185 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5186 Node* n;
5187 n = mm->in(idx);
5188 if (mem == n) return true; // might be empty_memory()
5189 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5190 if (mem == n) return true;
5191 return false;
5192 }
5193 #endif // !PRODUCT