1 /*
2 * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "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->exact_klass()->equals(t_oop->is_instptr()->exact_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 bool do_split = false;
222 // In the following cases, Load memory input can be further optimized based on
223 // its precise address type
224 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
225 do_split = true;
226 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
227 const TypeOopPtr* mem_t =
228 t->is_oopptr()->cast_to_exactness(true)
229 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
230 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
231 if (t_oop->is_aryptr()) {
232 mem_t = mem_t->is_aryptr()
233 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
234 ->cast_to_size(t_oop->is_aryptr()->size())
235 ->with_offset(t_oop->is_aryptr()->offset())
236 ->is_aryptr();
237 }
238 do_split = mem_t == t_oop;
239 }
240 if (do_split) {
241 // clone the Phi with our address type
242 result = mphi->split_out_instance(t_adr, igvn);
243 } else {
244 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
245 }
246 }
247 return result;
248 }
249
250 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
251 uint alias_idx = phase->C->get_alias_index(tp);
252 Node *mem = mmem;
253 #ifdef ASSERT
254 {
255 // Check that current type is consistent with the alias index used during graph construction
256 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
257 bool consistent = adr_check == NULL || adr_check->empty() ||
258 phase->C->must_alias(adr_check, alias_idx );
259 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
260 if( !consistent && adr_check != NULL && !adr_check->empty() &&
261 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
262 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
263 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
264 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
265 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
266 // don't assert if it is dead code.
267 consistent = true;
268 }
269 if( !consistent ) {
270 st->print("alias_idx==%d, adr_check==", alias_idx);
271 if( adr_check == NULL ) {
272 st->print("NULL");
273 } else {
274 adr_check->dump();
275 }
276 st->cr();
277 print_alias_types();
278 assert(consistent, "adr_check must match alias idx");
279 }
280 }
281 #endif
282 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
283 // means an array I have not precisely typed yet. Do not do any
284 // alias stuff with it any time soon.
285 const TypeOopPtr *toop = tp->isa_oopptr();
286 if (tp->base() != Type::AnyPtr &&
287 !(toop &&
288 toop->isa_instptr() &&
289 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
290 toop->offset() == Type::OffsetBot)) {
291 // compress paths and change unreachable cycles to TOP
292 // If not, we can update the input infinitely along a MergeMem cycle
293 // Equivalent code in PhiNode::Ideal
294 Node* m = phase->transform(mmem);
295 // If transformed to a MergeMem, get the desired slice
296 // Otherwise the returned node represents memory for every slice
297 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
298 // Update input if it is progress over what we have now
299 }
300 return mem;
301 }
302
303 //--------------------------Ideal_common---------------------------------------
304 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
305 // Unhook non-raw memories from complete (macro-expanded) initializations.
306 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
307 // If our control input is a dead region, kill all below the region
308 Node *ctl = in(MemNode::Control);
309 if (ctl && remove_dead_region(phase, can_reshape))
310 return this;
311 ctl = in(MemNode::Control);
312 // Don't bother trying to transform a dead node
313 if (ctl && ctl->is_top()) return NodeSentinel;
314
315 PhaseIterGVN *igvn = phase->is_IterGVN();
316 // Wait if control on the worklist.
317 if (ctl && can_reshape && igvn != NULL) {
318 Node* bol = NULL;
319 Node* cmp = NULL;
320 if (ctl->in(0)->is_If()) {
321 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
322 bol = ctl->in(0)->in(1);
323 if (bol->is_Bool())
324 cmp = ctl->in(0)->in(1)->in(1);
325 }
326 if (igvn->_worklist.member(ctl) ||
327 (bol != NULL && igvn->_worklist.member(bol)) ||
328 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
329 // This control path may be dead.
330 // Delay this memory node transformation until the control is processed.
331 igvn->_worklist.push(this);
332 return NodeSentinel; // caller will return NULL
333 }
334 }
335 // Ignore if memory is dead, or self-loop
336 Node *mem = in(MemNode::Memory);
337 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
338 assert(mem != this, "dead loop in MemNode::Ideal");
339
340 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
341 // This memory slice may be dead.
342 // Delay this mem node transformation until the memory is processed.
343 igvn->_worklist.push(this);
344 return NodeSentinel; // caller will return NULL
345 }
346
347 Node *address = in(MemNode::Address);
348 const Type *t_adr = phase->type(address);
349 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
350
351 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
352 // Unsafe off-heap access with zero address. Remove access and other control users
353 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
354 assert(ctl != NULL, "unsafe accesses should be control dependent");
355 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
356 Node* u = ctl->fast_out(i);
357 if (u != ctl) {
358 igvn->rehash_node_delayed(u);
359 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
360 --i, imax -= nb;
361 }
362 }
363 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
364 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
365 phase->C->root()->add_req(halt);
366 return this;
367 }
368
369 if (can_reshape && igvn != NULL &&
370 (igvn->_worklist.member(address) ||
371 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
372 // The address's base and type may change when the address is processed.
373 // Delay this mem node transformation until the address is processed.
374 igvn->_worklist.push(this);
375 return NodeSentinel; // caller will return NULL
376 }
377
378 // Do NOT remove or optimize the next lines: ensure a new alias index
379 // is allocated for an oop pointer type before Escape Analysis.
380 // Note: C++ will not remove it since the call has side effect.
381 if (t_adr->isa_oopptr()) {
382 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
383 }
384
385 Node* base = NULL;
386 if (address->is_AddP()) {
387 base = address->in(AddPNode::Base);
388 }
389 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
390 !t_adr->isa_rawptr()) {
391 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
392 // Skip this node optimization if its address has TOP base.
393 return NodeSentinel; // caller will return NULL
394 }
395
396 // Avoid independent memory operations
397 Node* old_mem = mem;
398
399 // The code which unhooks non-raw memories from complete (macro-expanded)
400 // initializations was removed. After macro-expansion all stores caught
401 // by Initialize node became raw stores and there is no information
402 // which memory slices they modify. So it is unsafe to move any memory
403 // operation above these stores. Also in most cases hooked non-raw memories
404 // were already unhooked by using information from detect_ptr_independence()
405 // and find_previous_store().
406
407 if (mem->is_MergeMem()) {
408 MergeMemNode* mmem = mem->as_MergeMem();
409 const TypePtr *tp = t_adr->is_ptr();
410
411 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
412 }
413
414 if (mem != old_mem) {
415 set_req_X(MemNode::Memory, mem, phase);
416 if (phase->type(mem) == Type::TOP) return NodeSentinel;
417 return this;
418 }
419
420 // let the subclass continue analyzing...
421 return NULL;
422 }
423
424 // Helper function for proving some simple control dominations.
425 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
426 // Already assumes that 'dom' is available at 'sub', and that 'sub'
427 // is not a constant (dominated by the method's StartNode).
428 // Used by MemNode::find_previous_store to prove that the
429 // control input of a memory operation predates (dominates)
430 // an allocation it wants to look past.
431 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
432 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
433 return false; // Conservative answer for dead code
434
435 // Check 'dom'. Skip Proj and CatchProj nodes.
436 dom = dom->find_exact_control(dom);
437 if (dom == NULL || dom->is_top())
438 return false; // Conservative answer for dead code
439
440 if (dom == sub) {
441 // For the case when, for example, 'sub' is Initialize and the original
442 // 'dom' is Proj node of the 'sub'.
443 return false;
444 }
445
446 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
447 return true;
448
449 // 'dom' dominates 'sub' if its control edge and control edges
450 // of all its inputs dominate or equal to sub's control edge.
451
452 // Currently 'sub' is either Allocate, Initialize or Start nodes.
453 // Or Region for the check in LoadNode::Ideal();
454 // 'sub' should have sub->in(0) != NULL.
455 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
456 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
457
458 // Get control edge of 'sub'.
459 Node* orig_sub = sub;
460 sub = sub->find_exact_control(sub->in(0));
461 if (sub == NULL || sub->is_top())
462 return false; // Conservative answer for dead code
463
464 assert(sub->is_CFG(), "expecting control");
465
466 if (sub == dom)
467 return true;
468
469 if (sub->is_Start() || sub->is_Root())
470 return false;
471
472 {
473 // Check all control edges of 'dom'.
474
475 ResourceMark rm;
476 Node_List nlist;
477 Unique_Node_List dom_list;
478
479 dom_list.push(dom);
480 bool only_dominating_controls = false;
481
482 for (uint next = 0; next < dom_list.size(); next++) {
483 Node* n = dom_list.at(next);
484 if (n == orig_sub)
485 return false; // One of dom's inputs dominated by sub.
486 if (!n->is_CFG() && n->pinned()) {
487 // Check only own control edge for pinned non-control nodes.
488 n = n->find_exact_control(n->in(0));
489 if (n == NULL || n->is_top())
490 return false; // Conservative answer for dead code
491 assert(n->is_CFG(), "expecting control");
492 dom_list.push(n);
493 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
494 only_dominating_controls = true;
495 } else if (n->is_CFG()) {
496 if (n->dominates(sub, nlist))
497 only_dominating_controls = true;
498 else
499 return false;
500 } else {
501 // First, own control edge.
502 Node* m = n->find_exact_control(n->in(0));
503 if (m != NULL) {
504 if (m->is_top())
505 return false; // Conservative answer for dead code
506 dom_list.push(m);
507 }
508 // Now, the rest of edges.
509 uint cnt = n->req();
510 for (uint i = 1; i < cnt; i++) {
511 m = n->find_exact_control(n->in(i));
512 if (m == NULL || m->is_top())
513 continue;
514 dom_list.push(m);
515 }
516 }
517 }
518 return only_dominating_controls;
519 }
520 }
521
522 //---------------------detect_ptr_independence---------------------------------
523 // Used by MemNode::find_previous_store to prove that two base
524 // pointers are never equal.
525 // The pointers are accompanied by their associated allocations,
526 // if any, which have been previously discovered by the caller.
527 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
528 Node* p2, AllocateNode* a2,
529 PhaseTransform* phase) {
530 // Attempt to prove that these two pointers cannot be aliased.
531 // They may both manifestly be allocations, and they should differ.
532 // Or, if they are not both allocations, they can be distinct constants.
533 // Otherwise, one is an allocation and the other a pre-existing value.
534 if (a1 == NULL && a2 == NULL) { // neither an allocation
535 return (p1 != p2) && p1->is_Con() && p2->is_Con();
536 } else if (a1 != NULL && a2 != NULL) { // both allocations
537 return (a1 != a2);
538 } else if (a1 != NULL) { // one allocation a1
539 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
540 return all_controls_dominate(p2, a1);
541 } else { //(a2 != NULL) // one allocation a2
542 return all_controls_dominate(p1, a2);
543 }
544 return false;
545 }
546
547
548 // Find an arraycopy ac that produces the memory state represented by parameter mem.
549 // Return ac if
550 // (a) can_see_stored_value=true and ac must have set the value for this load or if
551 // (b) can_see_stored_value=false and ac could have set the value for this load or if
552 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
553 // In case (c) change the parameter mem to the memory input of ac to skip it
554 // when searching stored value.
555 // Otherwise return NULL.
556 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
557 ArrayCopyNode* ac = find_array_copy_clone(phase, ld_alloc, mem);
558 if (ac != NULL) {
559 Node* ld_addp = in(MemNode::Address);
560 Node* src = ac->in(ArrayCopyNode::Src);
561 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
562
563 // This is a load from a cloned array. The corresponding arraycopy ac must
564 // have set the value for the load and we can return ac but only if the load
565 // is known to be within bounds. This is checked below.
566 if (ary_t != NULL && ld_addp->is_AddP()) {
567 Node* ld_offs = ld_addp->in(AddPNode::Offset);
568 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
569 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
570 jlong elemsize = type2aelembytes(ary_elem);
571
572 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
573 const TypeInt* sizetype = ary_t->size();
574
575 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
576 // The load is known to be within bounds. It receives its value from ac.
577 return ac;
578 }
579 // The load is known to be out-of-bounds.
580 }
581 // The load could be out-of-bounds. It must not be hoisted but must remain
582 // dependent on the runtime range check. This is achieved by returning NULL.
583 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
584 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
585
586 if (ac->is_arraycopy_validated() ||
587 ac->is_copyof_validated() ||
588 ac->is_copyofrange_validated()) {
589 Node* ld_addp = in(MemNode::Address);
590 if (ld_addp->is_AddP()) {
591 Node* ld_base = ld_addp->in(AddPNode::Address);
592 Node* ld_offs = ld_addp->in(AddPNode::Offset);
593
594 Node* dest = ac->in(ArrayCopyNode::Dest);
595
596 if (dest == ld_base) {
597 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
598 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
599 return ac;
600 }
601 if (!can_see_stored_value) {
602 mem = ac->in(TypeFunc::Memory);
603 return ac;
604 }
605 }
606 }
607 }
608 }
609 return NULL;
610 }
611
612 ArrayCopyNode* MemNode::find_array_copy_clone(PhaseTransform* phase, Node* ld_alloc, Node* mem) const {
613 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
614 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
615 if (ld_alloc != NULL) {
616 // Check if there is an array copy for a clone
617 Node* mb = mem->in(0);
618 ArrayCopyNode* ac = NULL;
619 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
620 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
621 ac = mb->in(0)->in(0)->as_ArrayCopy();
622 } else {
623 // Step over GC barrier when ReduceInitialCardMarks is disabled
624 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
625 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
626
627 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
628 ac = control_proj_ac->in(0)->as_ArrayCopy();
629 }
630 }
631
632 if (ac != NULL && ac->is_clonebasic()) {
633 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase);
634 if (alloc != NULL && alloc == ld_alloc) {
635 return ac;
636 }
637 }
638 }
639 }
640 return NULL;
641 }
642
643 // The logic for reordering loads and stores uses four steps:
644 // (a) Walk carefully past stores and initializations which we
645 // can prove are independent of this load.
646 // (b) Observe that the next memory state makes an exact match
647 // with self (load or store), and locate the relevant store.
648 // (c) Ensure that, if we were to wire self directly to the store,
649 // the optimizer would fold it up somehow.
650 // (d) Do the rewiring, and return, depending on some other part of
651 // the optimizer to fold up the load.
652 // This routine handles steps (a) and (b). Steps (c) and (d) are
653 // specific to loads and stores, so they are handled by the callers.
654 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
655 //
656 Node* MemNode::find_previous_store(PhaseTransform* phase) {
657 Node* ctrl = in(MemNode::Control);
658 Node* adr = in(MemNode::Address);
659 intptr_t offset = 0;
660 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
661 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
662
663 if (offset == Type::OffsetBot)
664 return NULL; // cannot unalias unless there are precise offsets
665
666 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
667 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
668
669 intptr_t size_in_bytes = memory_size();
670
671 Node* mem = in(MemNode::Memory); // start searching here...
672
673 int cnt = 50; // Cycle limiter
674 for (;;) { // While we can dance past unrelated stores...
675 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
676
677 Node* prev = mem;
678 if (mem->is_Store()) {
679 Node* st_adr = mem->in(MemNode::Address);
680 intptr_t st_offset = 0;
681 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
682 if (st_base == NULL)
683 break; // inscrutable pointer
684
685 // For raw accesses it's not enough to prove that constant offsets don't intersect.
686 // We need the bases to be the equal in order for the offset check to make sense.
687 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
688 break;
689 }
690
691 if (st_offset != offset && st_offset != Type::OffsetBot) {
692 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
693 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
694 if (st_offset >= offset + size_in_bytes ||
695 st_offset <= offset - MAX_STORE ||
696 st_offset <= offset - mem->as_Store()->memory_size()) {
697 // Success: The offsets are provably independent.
698 // (You may ask, why not just test st_offset != offset and be done?
699 // The answer is that stores of different sizes can co-exist
700 // in the same sequence of RawMem effects. We sometimes initialize
701 // a whole 'tile' of array elements with a single jint or jlong.)
702 mem = mem->in(MemNode::Memory);
703 continue; // (a) advance through independent store memory
704 }
705 }
706 if (st_base != base &&
707 detect_ptr_independence(base, alloc,
708 st_base,
709 AllocateNode::Ideal_allocation(st_base, phase),
710 phase)) {
711 // Success: The bases are provably independent.
712 mem = mem->in(MemNode::Memory);
713 continue; // (a) advance through independent store memory
714 }
715
716 // (b) At this point, if the bases or offsets do not agree, we lose,
717 // since we have not managed to prove 'this' and 'mem' independent.
718 if (st_base == base && st_offset == offset) {
719 return mem; // let caller handle steps (c), (d)
720 }
721
722 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
723 InitializeNode* st_init = mem->in(0)->as_Initialize();
724 AllocateNode* st_alloc = st_init->allocation();
725 if (st_alloc == NULL)
726 break; // something degenerated
727 bool known_identical = false;
728 bool known_independent = false;
729 if (alloc == st_alloc)
730 known_identical = true;
731 else if (alloc != NULL)
732 known_independent = true;
733 else if (all_controls_dominate(this, st_alloc))
734 known_independent = true;
735
736 if (known_independent) {
737 // The bases are provably independent: Either they are
738 // manifestly distinct allocations, or else the control
739 // of this load dominates the store's allocation.
740 int alias_idx = phase->C->get_alias_index(adr_type());
741 if (alias_idx == Compile::AliasIdxRaw) {
742 mem = st_alloc->in(TypeFunc::Memory);
743 } else {
744 mem = st_init->memory(alias_idx);
745 }
746 continue; // (a) advance through independent store memory
747 }
748
749 // (b) at this point, if we are not looking at a store initializing
750 // the same allocation we are loading from, we lose.
751 if (known_identical) {
752 // From caller, can_see_stored_value will consult find_captured_store.
753 return mem; // let caller handle steps (c), (d)
754 }
755
756 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
757 if (prev != mem) {
758 // Found an arraycopy but it doesn't affect that load
759 continue;
760 }
761 // Found an arraycopy that may affect that load
762 return mem;
763 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
764 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
765 if (mem->is_Proj() && mem->in(0)->is_Call()) {
766 // ArrayCopyNodes processed here as well.
767 CallNode *call = mem->in(0)->as_Call();
768 if (!call->may_modify(addr_t, phase)) {
769 mem = call->in(TypeFunc::Memory);
770 continue; // (a) advance through independent call memory
771 }
772 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
773 ArrayCopyNode* ac = NULL;
774 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
775 break;
776 }
777 mem = mem->in(0)->in(TypeFunc::Memory);
778 continue; // (a) advance through independent MemBar memory
779 } else if (mem->is_ClearArray()) {
780 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
781 // (the call updated 'mem' value)
782 continue; // (a) advance through independent allocation memory
783 } else {
784 // Can not bypass initialization of the instance
785 // we are looking for.
786 return mem;
787 }
788 } else if (mem->is_MergeMem()) {
789 int alias_idx = phase->C->get_alias_index(adr_type());
790 mem = mem->as_MergeMem()->memory_at(alias_idx);
791 continue; // (a) advance through independent MergeMem memory
792 }
793 }
794
795 // Unless there is an explicit 'continue', we must bail out here,
796 // because 'mem' is an inscrutable memory state (e.g., a call).
797 break;
798 }
799
800 return NULL; // bail out
801 }
802
803 //----------------------calculate_adr_type-------------------------------------
804 // Helper function. Notices when the given type of address hits top or bottom.
805 // Also, asserts a cross-check of the type against the expected address type.
806 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
807 if (t == Type::TOP) return NULL; // does not touch memory any more?
808 #ifdef ASSERT
809 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = NULL;
810 #endif
811 const TypePtr* tp = t->isa_ptr();
812 if (tp == NULL) {
813 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
814 return TypePtr::BOTTOM; // touches lots of memory
815 } else {
816 #ifdef ASSERT
817 // %%%% [phh] We don't check the alias index if cross_check is
818 // TypeRawPtr::BOTTOM. Needs to be investigated.
819 if (cross_check != NULL &&
820 cross_check != TypePtr::BOTTOM &&
821 cross_check != TypeRawPtr::BOTTOM) {
822 // Recheck the alias index, to see if it has changed (due to a bug).
823 Compile* C = Compile::current();
824 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
825 "must stay in the original alias category");
826 // The type of the address must be contained in the adr_type,
827 // disregarding "null"-ness.
828 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
829 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
830 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
831 "real address must not escape from expected memory type");
832 }
833 #endif
834 return tp;
835 }
836 }
837
838 //=============================================================================
839 // Should LoadNode::Ideal() attempt to remove control edges?
840 bool LoadNode::can_remove_control() const {
841 return !has_pinned_control_dependency();
842 }
843 uint LoadNode::size_of() const { return sizeof(*this); }
844 bool LoadNode::cmp( const Node &n ) const
845 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
846 const Type *LoadNode::bottom_type() const { return _type; }
847 uint LoadNode::ideal_reg() const {
848 return _type->ideal_reg();
849 }
850
851 #ifndef PRODUCT
852 void LoadNode::dump_spec(outputStream *st) const {
853 MemNode::dump_spec(st);
854 if( !Verbose && !WizardMode ) {
855 // standard dump does this in Verbose and WizardMode
856 st->print(" #"); _type->dump_on(st);
857 }
858 if (!depends_only_on_test()) {
859 st->print(" (does not depend only on test, ");
860 if (control_dependency() == UnknownControl) {
861 st->print("unknown control");
862 } else if (control_dependency() == Pinned) {
863 st->print("pinned");
864 } else if (adr_type() == TypeRawPtr::BOTTOM) {
865 st->print("raw access");
866 } else {
867 st->print("unknown reason");
868 }
869 st->print(")");
870 }
871 }
872 #endif
873
874 #ifdef ASSERT
875 //----------------------------is_immutable_value-------------------------------
876 // Helper function to allow a raw load without control edge for some cases
877 bool LoadNode::is_immutable_value(Node* adr) {
878 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
879 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
880
881 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
882 int offsets[] = {
883 in_bytes(JavaThread::osthread_offset()),
884 in_bytes(JavaThread::threadObj_offset()),
885 in_bytes(JavaThread::vthread_offset()),
886 in_bytes(JavaThread::scopedValueCache_offset()),
887 };
888
889 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
890 if (offset == offsets[i]) {
891 return true;
892 }
893 }
894 }
895
896 return false;
897 }
898 #endif
899
900 //----------------------------LoadNode::make-----------------------------------
901 // Polymorphic factory method:
902 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
903 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
904 Compile* C = gvn.C;
905
906 // sanity check the alias category against the created node type
907 assert(!(adr_type->isa_oopptr() &&
908 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
909 "use LoadKlassNode instead");
910 assert(!(adr_type->isa_aryptr() &&
911 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
912 "use LoadRangeNode instead");
913 // Check control edge of raw loads
914 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
915 // oop will be recorded in oop map if load crosses safepoint
916 rt->isa_oopptr() || is_immutable_value(adr),
917 "raw memory operations should have control edge");
918 LoadNode* load = NULL;
919 switch (bt) {
920 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
921 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
922 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
923 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
924 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
925 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
926 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
927 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
928 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
929 case T_PRIMITIVE_OBJECT:
930 case T_OBJECT:
931 #ifdef _LP64
932 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
933 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
934 } else
935 #endif
936 {
937 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
938 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
939 }
940 break;
941 default:
942 ShouldNotReachHere();
943 break;
944 }
945 assert(load != NULL, "LoadNode should have been created");
946 if (unaligned) {
947 load->set_unaligned_access();
948 }
949 if (mismatched) {
950 load->set_mismatched_access();
951 }
952 if (unsafe) {
953 load->set_unsafe_access();
954 }
955 load->set_barrier_data(barrier_data);
956 if (load->Opcode() == Op_LoadN) {
957 Node* ld = gvn.transform(load);
958 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
959 }
960
961 return load;
962 }
963
964 //------------------------------hash-------------------------------------------
965 uint LoadNode::hash() const {
966 // unroll addition of interesting fields
967 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
968 }
969
970 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
971 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
972 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
973 bool is_stable_ary = FoldStableValues &&
974 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
975 tp->isa_aryptr()->is_stable();
976
977 return (eliminate_boxing && non_volatile) || is_stable_ary;
978 }
979
980 return false;
981 }
982
983 // Is the value loaded previously stored by an arraycopy? If so return
984 // a load node that reads from the source array so we may be able to
985 // optimize out the ArrayCopy node later.
986 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
987 Node* ld_adr = in(MemNode::Address);
988 intptr_t ld_off = 0;
989 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
990 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
991 if (ac != NULL) {
992 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
993
994 Node* mem = ac->in(TypeFunc::Memory);
995 Node* ctl = ac->in(0);
996 Node* src = ac->in(ArrayCopyNode::Src);
997
998 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
999 return NULL;
1000 }
1001
1002 LoadNode* ld = clone()->as_Load();
1003 Node* addp = in(MemNode::Address)->clone();
1004 if (ac->as_ArrayCopy()->is_clonebasic()) {
1005 assert(ld_alloc != NULL, "need an alloc");
1006 assert(addp->is_AddP(), "address must be addp");
1007 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1008 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1009 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1010 addp->set_req(AddPNode::Base, src);
1011 addp->set_req(AddPNode::Address, src);
1012 } else {
1013 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1014 ac->as_ArrayCopy()->is_copyof_validated() ||
1015 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1016 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1017 addp->set_req(AddPNode::Base, src);
1018 addp->set_req(AddPNode::Address, src);
1019
1020 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1021 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1022 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1023
1024 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1025 uint shift = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem));
1026
1027 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1028 #ifdef _LP64
1029 diff = phase->transform(new ConvI2LNode(diff));
1030 #endif
1031 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1032
1033 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1034 addp->set_req(AddPNode::Offset, offset);
1035 }
1036 addp = phase->transform(addp);
1037 #ifdef ASSERT
1038 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1039 ld->_adr_type = adr_type;
1040 #endif
1041 ld->set_req(MemNode::Address, addp);
1042 ld->set_req(0, ctl);
1043 ld->set_req(MemNode::Memory, mem);
1044 // load depends on the tests that validate the arraycopy
1045 ld->_control_dependency = UnknownControl;
1046 return ld;
1047 }
1048 return NULL;
1049 }
1050
1051
1052 //---------------------------can_see_stored_value------------------------------
1053 // This routine exists to make sure this set of tests is done the same
1054 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1055 // will change the graph shape in a way which makes memory alive twice at the
1056 // same time (uses the Oracle model of aliasing), then some
1057 // LoadXNode::Identity will fold things back to the equivalence-class model
1058 // of aliasing.
1059 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
1060 Node* ld_adr = in(MemNode::Address);
1061 intptr_t ld_off = 0;
1062 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1063 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base, phase);
1064 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1065 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
1066 // This is more general than load from boxing objects.
1067 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1068 uint alias_idx = atp->index();
1069 Node* result = NULL;
1070 Node* current = st;
1071 // Skip through chains of MemBarNodes checking the MergeMems for
1072 // new states for the slice of this load. Stop once any other
1073 // kind of node is encountered. Loads from final memory can skip
1074 // through any kind of MemBar but normal loads shouldn't skip
1075 // through MemBarAcquire since the could allow them to move out of
1076 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1077 // because alias info above them may be inaccurate (e.g., due to
1078 // mixed/mismatched unsafe accesses).
1079 bool is_final_mem = !atp->is_rewritable();
1080 while (current->is_Proj()) {
1081 int opc = current->in(0)->Opcode();
1082 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1083 opc == Op_MemBarAcquireLock ||
1084 opc == Op_LoadFence)) ||
1085 opc == Op_MemBarRelease ||
1086 opc == Op_StoreFence ||
1087 opc == Op_MemBarReleaseLock ||
1088 opc == Op_MemBarStoreStore ||
1089 opc == Op_StoreStoreFence) {
1090 Node* mem = current->in(0)->in(TypeFunc::Memory);
1091 if (mem->is_MergeMem()) {
1092 MergeMemNode* merge = mem->as_MergeMem();
1093 Node* new_st = merge->memory_at(alias_idx);
1094 if (new_st == merge->base_memory()) {
1095 // Keep searching
1096 current = new_st;
1097 continue;
1098 }
1099 // Save the new memory state for the slice and fall through
1100 // to exit.
1101 result = new_st;
1102 }
1103 }
1104 break;
1105 }
1106 if (result != NULL) {
1107 st = result;
1108 }
1109 }
1110
1111 // Loop around twice in the case Load -> Initialize -> Store.
1112 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1113 for (int trip = 0; trip <= 1; trip++) {
1114
1115 if (st->is_Store()) {
1116 Node* st_adr = st->in(MemNode::Address);
1117 if (st_adr != ld_adr) {
1118 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1119 intptr_t st_off = 0;
1120 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1121 if (ld_base == NULL) return NULL;
1122 if (st_base == NULL) return NULL;
1123 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return NULL;
1124 if (ld_off != st_off) return NULL;
1125 if (ld_off == Type::OffsetBot) return NULL;
1126 // Same base, same offset.
1127 // Possible improvement for arrays: check index value instead of absolute offset.
1128
1129 // At this point we have proven something like this setup:
1130 // B = << base >>
1131 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1132 // S = StoreQ(AddP( B , #Off), V)
1133 // (Actually, we haven't yet proven the Q's are the same.)
1134 // In other words, we are loading from a casted version of
1135 // the same pointer-and-offset that we stored to.
1136 // Casted version may carry a dependency and it is respected.
1137 // Thus, we are able to replace L by V.
1138 }
1139 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1140 if (store_Opcode() != st->Opcode()) {
1141 return NULL;
1142 }
1143 // LoadVector/StoreVector needs additional check to ensure the types match.
1144 if (st->is_StoreVector()) {
1145 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1146 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1147 if (in_vt != out_vt) {
1148 return NULL;
1149 }
1150 }
1151 return st->in(MemNode::ValueIn);
1152 }
1153
1154 // A load from a freshly-created object always returns zero.
1155 // (This can happen after LoadNode::Ideal resets the load's memory input
1156 // to find_captured_store, which returned InitializeNode::zero_memory.)
1157 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1158 (st->in(0) == ld_alloc) &&
1159 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1160 // return a zero value for the load's basic type
1161 // (This is one of the few places where a generic PhaseTransform
1162 // can create new nodes. Think of it as lazily manifesting
1163 // virtually pre-existing constants.)
1164 assert(memory_type() != T_PRIMITIVE_OBJECT, "should not be used for inline types");
1165 Node* default_value = ld_alloc->in(AllocateNode::DefaultValue);
1166 if (default_value != NULL) {
1167 return default_value;
1168 }
1169 assert(ld_alloc->in(AllocateNode::RawDefaultValue) == NULL, "default value may not be null");
1170 if (memory_type() != T_VOID) {
1171 if (ReduceBulkZeroing || find_array_copy_clone(phase, ld_alloc, in(MemNode::Memory)) == NULL) {
1172 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1173 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1174 // by the ArrayCopyNode.
1175 return phase->zerocon(memory_type());
1176 }
1177 } else {
1178 // TODO: materialize all-zero vector constant
1179 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1180 }
1181 }
1182
1183 // A load from an initialization barrier can match a captured store.
1184 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1185 InitializeNode* init = st->in(0)->as_Initialize();
1186 AllocateNode* alloc = init->allocation();
1187 if ((alloc != NULL) && (alloc == ld_alloc)) {
1188 // examine a captured store value
1189 st = init->find_captured_store(ld_off, memory_size(), phase);
1190 if (st != NULL) {
1191 continue; // take one more trip around
1192 }
1193 }
1194 }
1195
1196 // Load boxed value from result of valueOf() call is input parameter.
1197 if (this->is_Load() && ld_adr->is_AddP() &&
1198 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1199 intptr_t ignore = 0;
1200 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1201 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1202 base = bs->step_over_gc_barrier(base);
1203 if (base != NULL && base->is_Proj() &&
1204 base->as_Proj()->_con == TypeFunc::Parms &&
1205 base->in(0)->is_CallStaticJava() &&
1206 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1207 return base->in(0)->in(TypeFunc::Parms);
1208 }
1209 }
1210
1211 break;
1212 }
1213
1214 return NULL;
1215 }
1216
1217 //----------------------is_instance_field_load_with_local_phi------------------
1218 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1219 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1220 in(Address)->is_AddP() ) {
1221 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1222 // Only instances and boxed values.
1223 if( t_oop != NULL &&
1224 (t_oop->is_ptr_to_boxed_value() ||
1225 t_oop->is_known_instance_field()) &&
1226 t_oop->offset() != Type::OffsetBot &&
1227 t_oop->offset() != Type::OffsetTop) {
1228 return true;
1229 }
1230 }
1231 return false;
1232 }
1233
1234 //------------------------------Identity---------------------------------------
1235 // Loads are identity if previous store is to same address
1236 Node* LoadNode::Identity(PhaseGVN* phase) {
1237 // Loading from an InlineType? The InlineType has the values of
1238 // all fields as input. Look for the field with matching offset.
1239 Node* addr = in(Address);
1240 intptr_t offset;
1241 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
1242 if (base != NULL && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) {
1243 Node* value = base->as_InlineType()->field_value_by_offset((int)offset, true);
1244 if (value != NULL) {
1245 if (Opcode() == Op_LoadN) {
1246 // Encode oop value if we are loading a narrow oop
1247 assert(!phase->type(value)->isa_narrowoop(), "should already be decoded");
1248 value = phase->transform(new EncodePNode(value, bottom_type()));
1249 }
1250 return value;
1251 }
1252 }
1253
1254 // If the previous store-maker is the right kind of Store, and the store is
1255 // to the same address, then we are equal to the value stored.
1256 Node* mem = in(Memory);
1257 Node* value = can_see_stored_value(mem, phase);
1258 if( value ) {
1259 // byte, short & char stores truncate naturally.
1260 // A load has to load the truncated value which requires
1261 // some sort of masking operation and that requires an
1262 // Ideal call instead of an Identity call.
1263 if (memory_size() < BytesPerInt) {
1264 // If the input to the store does not fit with the load's result type,
1265 // it must be truncated via an Ideal call.
1266 if (!phase->type(value)->higher_equal(phase->type(this)))
1267 return this;
1268 }
1269 // (This works even when value is a Con, but LoadNode::Value
1270 // usually runs first, producing the singleton type of the Con.)
1271 if (!has_pinned_control_dependency() || value->is_Con()) {
1272 return value;
1273 } else {
1274 return this;
1275 }
1276 }
1277
1278 if (has_pinned_control_dependency()) {
1279 return this;
1280 }
1281 // Search for an existing data phi which was generated before for the same
1282 // instance's field to avoid infinite generation of phis in a loop.
1283 Node *region = mem->in(0);
1284 if (is_instance_field_load_with_local_phi(region)) {
1285 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1286 int this_index = phase->C->get_alias_index(addr_t);
1287 int this_offset = addr_t->offset();
1288 int this_iid = addr_t->instance_id();
1289 if (!addr_t->is_known_instance() &&
1290 addr_t->is_ptr_to_boxed_value()) {
1291 // Use _idx of address base (could be Phi node) for boxed values.
1292 intptr_t ignore = 0;
1293 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1294 if (base == NULL) {
1295 return this;
1296 }
1297 this_iid = base->_idx;
1298 }
1299 const Type* this_type = bottom_type();
1300 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1301 Node* phi = region->fast_out(i);
1302 if (phi->is_Phi() && phi != mem &&
1303 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1304 return phi;
1305 }
1306 }
1307 }
1308
1309 return this;
1310 }
1311
1312 // Construct an equivalent unsigned load.
1313 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1314 BasicType bt = T_ILLEGAL;
1315 const Type* rt = NULL;
1316 switch (Opcode()) {
1317 case Op_LoadUB: return this;
1318 case Op_LoadUS: return this;
1319 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1320 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1321 default:
1322 assert(false, "no unsigned variant: %s", Name());
1323 return NULL;
1324 }
1325 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1326 raw_adr_type(), rt, bt, _mo, _control_dependency,
1327 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1328 }
1329
1330 // Construct an equivalent signed load.
1331 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1332 BasicType bt = T_ILLEGAL;
1333 const Type* rt = NULL;
1334 switch (Opcode()) {
1335 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1336 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1337 case Op_LoadB: // fall through
1338 case Op_LoadS: // fall through
1339 case Op_LoadI: // fall through
1340 case Op_LoadL: return this;
1341 default:
1342 assert(false, "no signed variant: %s", Name());
1343 return NULL;
1344 }
1345 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1346 raw_adr_type(), rt, bt, _mo, _control_dependency,
1347 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1348 }
1349
1350 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1351 BasicType bt = rt->basic_type();
1352 switch (Opcode()) {
1353 case Op_LoadI: return (bt == T_FLOAT);
1354 case Op_LoadL: return (bt == T_DOUBLE);
1355 case Op_LoadF: return (bt == T_INT);
1356 case Op_LoadD: return (bt == T_LONG);
1357
1358 default: return false;
1359 }
1360 }
1361
1362 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1363 BasicType bt = rt->basic_type();
1364 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1365 bool is_mismatched = is_mismatched_access();
1366 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1367 if (raw_type == NULL) {
1368 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1369 }
1370 const int op = Opcode();
1371 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1372 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1373 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1374 raw_adr_type(), rt, bt, _mo, _control_dependency,
1375 require_atomic_access, is_unaligned_access(), is_mismatched);
1376 }
1377
1378 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1379 BasicType bt = vt->basic_type();
1380 switch (Opcode()) {
1381 case Op_StoreI: return (bt == T_FLOAT);
1382 case Op_StoreL: return (bt == T_DOUBLE);
1383 case Op_StoreF: return (bt == T_INT);
1384 case Op_StoreD: return (bt == T_LONG);
1385
1386 default: return false;
1387 }
1388 }
1389
1390 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1391 BasicType bt = vt->basic_type();
1392 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1393 const int op = Opcode();
1394 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1395 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1396 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1397 raw_adr_type(), val, bt, _mo, require_atomic_access);
1398
1399 bool is_mismatched = is_mismatched_access();
1400 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1401 if (raw_type == NULL) {
1402 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1403 }
1404 if (is_mismatched) {
1405 st->set_mismatched_access();
1406 }
1407 return st;
1408 }
1409
1410 // We're loading from an object which has autobox behaviour.
1411 // If this object is result of a valueOf call we'll have a phi
1412 // merging a newly allocated object and a load from the cache.
1413 // We want to replace this load with the original incoming
1414 // argument to the valueOf call.
1415 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1416 assert(igvn->C->eliminate_boxing(), "sanity");
1417 intptr_t ignore = 0;
1418 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1419 if ((base == NULL) || base->is_Phi()) {
1420 // Push the loads from the phi that comes from valueOf up
1421 // through it to allow elimination of the loads and the recovery
1422 // of the original value. It is done in split_through_phi().
1423 return NULL;
1424 } else if (base->is_Load() ||
1425 (base->is_DecodeN() && base->in(1)->is_Load())) {
1426 // Eliminate the load of boxed value for integer types from the cache
1427 // array by deriving the value from the index into the array.
1428 // Capture the offset of the load and then reverse the computation.
1429
1430 // Get LoadN node which loads a boxing object from 'cache' array.
1431 if (base->is_DecodeN()) {
1432 base = base->in(1);
1433 }
1434 if (!base->in(Address)->is_AddP()) {
1435 return NULL; // Complex address
1436 }
1437 AddPNode* address = base->in(Address)->as_AddP();
1438 Node* cache_base = address->in(AddPNode::Base);
1439 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1440 // Get ConP node which is static 'cache' field.
1441 cache_base = cache_base->in(1);
1442 }
1443 if ((cache_base != NULL) && cache_base->is_Con()) {
1444 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1445 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1446 Node* elements[4];
1447 int shift = exact_log2(type2aelembytes(T_OBJECT));
1448 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1449 if (count > 0 && elements[0]->is_Con() &&
1450 (count == 1 ||
1451 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1452 elements[1]->in(2) == igvn->intcon(shift)))) {
1453 ciObjArray* array = base_type->const_oop()->as_obj_array();
1454 // Fetch the box object cache[0] at the base of the array and get its value
1455 ciInstance* box = array->obj_at(0)->as_instance();
1456 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1457 assert(ik->is_box_klass(), "sanity");
1458 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1459 if (ik->nof_nonstatic_fields() == 1) {
1460 // This should be true nonstatic_field_at requires calling
1461 // nof_nonstatic_fields so check it anyway
1462 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1463 BasicType bt = c.basic_type();
1464 // Only integer types have boxing cache.
1465 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1466 bt == T_BYTE || bt == T_SHORT ||
1467 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1468 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1469 if (cache_low != (int)cache_low) {
1470 return NULL; // should not happen since cache is array indexed by value
1471 }
1472 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1473 if (offset != (int)offset) {
1474 return NULL; // should not happen since cache is array indexed by value
1475 }
1476 // Add up all the offsets making of the address of the load
1477 Node* result = elements[0];
1478 for (int i = 1; i < count; i++) {
1479 result = igvn->transform(new AddXNode(result, elements[i]));
1480 }
1481 // Remove the constant offset from the address and then
1482 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1483 // remove the scaling of the offset to recover the original index.
1484 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1485 // Peel the shift off directly but wrap it in a dummy node
1486 // since Ideal can't return existing nodes
1487 igvn->_worklist.push(result); // remove dead node later
1488 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1489 } else if (result->is_Add() && result->in(2)->is_Con() &&
1490 result->in(1)->Opcode() == Op_LShiftX &&
1491 result->in(1)->in(2) == igvn->intcon(shift)) {
1492 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1493 // but for boxing cache access we know that X<<Z will not overflow
1494 // (there is range check) so we do this optimizatrion by hand here.
1495 igvn->_worklist.push(result); // remove dead node later
1496 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1497 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1498 } else {
1499 result = new RShiftXNode(result, igvn->intcon(shift));
1500 }
1501 #ifdef _LP64
1502 if (bt != T_LONG) {
1503 result = new ConvL2INode(igvn->transform(result));
1504 }
1505 #else
1506 if (bt == T_LONG) {
1507 result = new ConvI2LNode(igvn->transform(result));
1508 }
1509 #endif
1510 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1511 // Need to preserve unboxing load type if it is unsigned.
1512 switch(this->Opcode()) {
1513 case Op_LoadUB:
1514 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1515 break;
1516 case Op_LoadUS:
1517 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1518 break;
1519 }
1520 return result;
1521 }
1522 }
1523 }
1524 }
1525 }
1526 return NULL;
1527 }
1528
1529 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1530 Node* region = phi->in(0);
1531 if (region == NULL) {
1532 return false; // Wait stable graph
1533 }
1534 uint cnt = phi->req();
1535 for (uint i = 1; i < cnt; i++) {
1536 Node* rc = region->in(i);
1537 if (rc == NULL || phase->type(rc) == Type::TOP)
1538 return false; // Wait stable graph
1539 Node* in = phi->in(i);
1540 if (in == NULL || phase->type(in) == Type::TOP)
1541 return false; // Wait stable graph
1542 }
1543 return true;
1544 }
1545 //------------------------------split_through_phi------------------------------
1546 // Split instance or boxed field load through Phi.
1547 Node* LoadNode::split_through_phi(PhaseGVN* phase) {
1548 if (req() > 3) {
1549 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1550 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1551 return NULL;
1552 }
1553 Node* mem = in(Memory);
1554 Node* address = in(Address);
1555 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1556
1557 assert((t_oop != NULL) &&
1558 (t_oop->is_known_instance_field() ||
1559 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1560
1561 Compile* C = phase->C;
1562 intptr_t ignore = 0;
1563 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1564 bool base_is_phi = (base != NULL) && base->is_Phi();
1565 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1566 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1567 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1568
1569 if (!((mem->is_Phi() || base_is_phi) &&
1570 (load_boxed_values || t_oop->is_known_instance_field()))) {
1571 return NULL; // memory is not Phi
1572 }
1573
1574 if (mem->is_Phi()) {
1575 if (!stable_phi(mem->as_Phi(), phase)) {
1576 return NULL; // Wait stable graph
1577 }
1578 uint cnt = mem->req();
1579 // Check for loop invariant memory.
1580 if (cnt == 3) {
1581 for (uint i = 1; i < cnt; i++) {
1582 Node* in = mem->in(i);
1583 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1584 if (m == mem) {
1585 if (i == 1) {
1586 // if the first edge was a loop, check second edge too.
1587 // If both are replaceable - we are in an infinite loop
1588 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1589 if (n == mem) {
1590 break;
1591 }
1592 }
1593 set_req(Memory, mem->in(cnt - i));
1594 return this; // made change
1595 }
1596 }
1597 }
1598 }
1599 if (base_is_phi) {
1600 if (!stable_phi(base->as_Phi(), phase)) {
1601 return NULL; // Wait stable graph
1602 }
1603 uint cnt = base->req();
1604 // Check for loop invariant memory.
1605 if (cnt == 3) {
1606 for (uint i = 1; i < cnt; i++) {
1607 if (base->in(i) == base) {
1608 return NULL; // Wait stable graph
1609 }
1610 }
1611 }
1612 }
1613
1614 // Split through Phi (see original code in loopopts.cpp).
1615 assert(C->have_alias_type(t_oop), "instance should have alias type");
1616
1617 // Do nothing here if Identity will find a value
1618 // (to avoid infinite chain of value phis generation).
1619 if (this != Identity(phase)) {
1620 return NULL;
1621 }
1622
1623 // Select Region to split through.
1624 Node* region;
1625 if (!base_is_phi) {
1626 assert(mem->is_Phi(), "sanity");
1627 region = mem->in(0);
1628 // Skip if the region dominates some control edge of the address.
1629 if (!MemNode::all_controls_dominate(address, region))
1630 return NULL;
1631 } else if (!mem->is_Phi()) {
1632 assert(base_is_phi, "sanity");
1633 region = base->in(0);
1634 // Skip if the region dominates some control edge of the memory.
1635 if (!MemNode::all_controls_dominate(mem, region))
1636 return NULL;
1637 } else if (base->in(0) != mem->in(0)) {
1638 assert(base_is_phi && mem->is_Phi(), "sanity");
1639 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1640 region = base->in(0);
1641 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1642 region = mem->in(0);
1643 } else {
1644 return NULL; // complex graph
1645 }
1646 } else {
1647 assert(base->in(0) == mem->in(0), "sanity");
1648 region = mem->in(0);
1649 }
1650
1651 const Type* this_type = this->bottom_type();
1652 int this_index = C->get_alias_index(t_oop);
1653 int this_offset = t_oop->offset();
1654 int this_iid = t_oop->instance_id();
1655 if (!t_oop->is_known_instance() && load_boxed_values) {
1656 // Use _idx of address base for boxed values.
1657 this_iid = base->_idx;
1658 }
1659 PhaseIterGVN* igvn = phase->is_IterGVN();
1660 Node* phi = new PhiNode(region, this_type, NULL, mem->_idx, this_iid, this_index, this_offset);
1661 for (uint i = 1; i < region->req(); i++) {
1662 Node* x;
1663 Node* the_clone = NULL;
1664 Node* in = region->in(i);
1665 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1666 in != NULL && in->is_OuterStripMinedLoop()) {
1667 // No node should go in the outer strip mined loop
1668 in = in->in(LoopNode::EntryControl);
1669 }
1670 if (in == NULL || in == C->top()) {
1671 x = C->top(); // Dead path? Use a dead data op
1672 } else {
1673 x = this->clone(); // Else clone up the data op
1674 the_clone = x; // Remember for possible deletion.
1675 // Alter data node to use pre-phi inputs
1676 if (this->in(0) == region) {
1677 x->set_req(0, in);
1678 } else {
1679 x->set_req(0, NULL);
1680 }
1681 if (mem->is_Phi() && (mem->in(0) == region)) {
1682 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1683 }
1684 if (address->is_Phi() && address->in(0) == region) {
1685 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1686 }
1687 if (base_is_phi && (base->in(0) == region)) {
1688 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1689 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1690 x->set_req(Address, adr_x);
1691 }
1692 }
1693 // Check for a 'win' on some paths
1694 const Type *t = x->Value(igvn);
1695
1696 bool singleton = t->singleton();
1697
1698 // See comments in PhaseIdealLoop::split_thru_phi().
1699 if (singleton && t == Type::TOP) {
1700 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1701 }
1702
1703 if (singleton) {
1704 x = igvn->makecon(t);
1705 } else {
1706 // We now call Identity to try to simplify the cloned node.
1707 // Note that some Identity methods call phase->type(this).
1708 // Make sure that the type array is big enough for
1709 // our new node, even though we may throw the node away.
1710 // (This tweaking with igvn only works because x is a new node.)
1711 igvn->set_type(x, t);
1712 // If x is a TypeNode, capture any more-precise type permanently into Node
1713 // otherwise it will be not updated during igvn->transform since
1714 // igvn->type(x) is set to x->Value() already.
1715 x->raise_bottom_type(t);
1716 Node* y = x->Identity(igvn);
1717 if (y != x) {
1718 x = y;
1719 } else {
1720 y = igvn->hash_find_insert(x);
1721 if (y) {
1722 x = y;
1723 } else {
1724 // Else x is a new node we are keeping
1725 // We do not need register_new_node_with_optimizer
1726 // because set_type has already been called.
1727 igvn->_worklist.push(x);
1728 }
1729 }
1730 }
1731 if (x != the_clone && the_clone != NULL) {
1732 igvn->remove_dead_node(the_clone);
1733 }
1734 phi->set_req(i, x);
1735 }
1736 // Record Phi
1737 igvn->register_new_node_with_optimizer(phi);
1738 return phi;
1739 }
1740
1741 AllocateNode* LoadNode::is_new_object_mark_load(PhaseGVN *phase) const {
1742 if (Opcode() == Op_LoadX) {
1743 Node* address = in(MemNode::Address);
1744 AllocateNode* alloc = AllocateNode::Ideal_allocation(address, phase);
1745 Node* mem = in(MemNode::Memory);
1746 if (alloc != NULL && mem->is_Proj() &&
1747 mem->in(0) != NULL &&
1748 mem->in(0) == alloc->initialization() &&
1749 alloc->initialization()->proj_out_or_null(0) != NULL) {
1750 return alloc;
1751 }
1752 }
1753 return NULL;
1754 }
1755
1756
1757 //------------------------------Ideal------------------------------------------
1758 // If the load is from Field memory and the pointer is non-null, it might be possible to
1759 // zero out the control input.
1760 // If the offset is constant and the base is an object allocation,
1761 // try to hook me up to the exact initializing store.
1762 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1763 if (has_pinned_control_dependency()) {
1764 return NULL;
1765 }
1766 Node* p = MemNode::Ideal_common(phase, can_reshape);
1767 if (p) return (p == NodeSentinel) ? NULL : p;
1768
1769 Node* ctrl = in(MemNode::Control);
1770 Node* address = in(MemNode::Address);
1771 bool progress = false;
1772
1773 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1774 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1775
1776 // Skip up past a SafePoint control. Cannot do this for Stores because
1777 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1778 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1779 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
1780 !addr_mark &&
1781 (depends_only_on_test() || has_unknown_control_dependency())) {
1782 ctrl = ctrl->in(0);
1783 set_req(MemNode::Control,ctrl);
1784 progress = true;
1785 }
1786
1787 intptr_t ignore = 0;
1788 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1789 if (base != NULL
1790 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1791 // Check for useless control edge in some common special cases
1792 if (in(MemNode::Control) != NULL
1793 && can_remove_control()
1794 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1795 && all_controls_dominate(base, phase->C->start())) {
1796 // A method-invariant, non-null address (constant or 'this' argument).
1797 set_req(MemNode::Control, NULL);
1798 progress = true;
1799 }
1800 }
1801
1802 Node* mem = in(MemNode::Memory);
1803 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1804
1805 if (can_reshape && (addr_t != NULL)) {
1806 // try to optimize our memory input
1807 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1808 if (opt_mem != mem) {
1809 set_req_X(MemNode::Memory, opt_mem, phase);
1810 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1811 return this;
1812 }
1813 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1814 if ((t_oop != NULL) &&
1815 (t_oop->is_known_instance_field() ||
1816 t_oop->is_ptr_to_boxed_value())) {
1817 PhaseIterGVN *igvn = phase->is_IterGVN();
1818 assert(igvn != NULL, "must be PhaseIterGVN when can_reshape is true");
1819 if (igvn->_worklist.member(opt_mem)) {
1820 // Delay this transformation until memory Phi is processed.
1821 igvn->_worklist.push(this);
1822 return NULL;
1823 }
1824 // Split instance field load through Phi.
1825 Node* result = split_through_phi(phase);
1826 if (result != NULL) return result;
1827
1828 if (t_oop->is_ptr_to_boxed_value()) {
1829 Node* result = eliminate_autobox(igvn);
1830 if (result != NULL) return result;
1831 }
1832 }
1833 }
1834
1835 // Is there a dominating load that loads the same value? Leave
1836 // anything that is not a load of a field/array element (like
1837 // barriers etc.) alone
1838 if (in(0) != NULL && !adr_type()->isa_rawptr() && can_reshape) {
1839 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1840 Node *use = mem->fast_out(i);
1841 if (use != this &&
1842 use->Opcode() == Opcode() &&
1843 use->in(0) != NULL &&
1844 use->in(0) != in(0) &&
1845 use->in(Address) == in(Address)) {
1846 Node* ctl = in(0);
1847 for (int i = 0; i < 10 && ctl != NULL; i++) {
1848 ctl = IfNode::up_one_dom(ctl);
1849 if (ctl == use->in(0)) {
1850 set_req(0, use->in(0));
1851 return this;
1852 }
1853 }
1854 }
1855 }
1856 }
1857
1858 // Check for prior store with a different base or offset; make Load
1859 // independent. Skip through any number of them. Bail out if the stores
1860 // are in an endless dead cycle and report no progress. This is a key
1861 // transform for Reflection. However, if after skipping through the Stores
1862 // we can't then fold up against a prior store do NOT do the transform as
1863 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1864 // array memory alive twice: once for the hoisted Load and again after the
1865 // bypassed Store. This situation only works if EVERYBODY who does
1866 // anti-dependence work knows how to bypass. I.e. we need all
1867 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1868 // the alias index stuff. So instead, peek through Stores and IFF we can
1869 // fold up, do so.
1870 Node* prev_mem = find_previous_store(phase);
1871 if (prev_mem != NULL) {
1872 Node* value = can_see_arraycopy_value(prev_mem, phase);
1873 if (value != NULL) {
1874 return value;
1875 }
1876 }
1877 // Steps (a), (b): Walk past independent stores to find an exact match.
1878 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1879 // (c) See if we can fold up on the spot, but don't fold up here.
1880 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1881 // just return a prior value, which is done by Identity calls.
1882 if (can_see_stored_value(prev_mem, phase)) {
1883 // Make ready for step (d):
1884 set_req_X(MemNode::Memory, prev_mem, phase);
1885 return this;
1886 }
1887 }
1888
1889 return progress ? this : NULL;
1890 }
1891
1892 // Helper to recognize certain Klass fields which are invariant across
1893 // some group of array types (e.g., int[] or all T[] where T < Object).
1894 const Type*
1895 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1896 ciKlass* klass) const {
1897 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1898 // The field is Klass::_modifier_flags. Return its (constant) value.
1899 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1900 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1901 return TypeInt::make(klass->modifier_flags());
1902 }
1903 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1904 // The field is Klass::_access_flags. Return its (constant) value.
1905 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1906 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1907 return TypeInt::make(klass->access_flags());
1908 }
1909 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1910 // The field is Klass::_layout_helper. Return its constant value if known.
1911 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1912 return TypeInt::make(klass->layout_helper());
1913 }
1914
1915 // No match.
1916 return NULL;
1917 }
1918
1919 //------------------------------Value-----------------------------------------
1920 const Type* LoadNode::Value(PhaseGVN* phase) const {
1921 // Either input is TOP ==> the result is TOP
1922 Node* mem = in(MemNode::Memory);
1923 const Type *t1 = phase->type(mem);
1924 if (t1 == Type::TOP) return Type::TOP;
1925 Node* adr = in(MemNode::Address);
1926 const TypePtr* tp = phase->type(adr)->isa_ptr();
1927 if (tp == NULL || tp->empty()) return Type::TOP;
1928 int off = tp->offset();
1929 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1930 Compile* C = phase->C;
1931
1932 // Try to guess loaded type from pointer type
1933 if (tp->isa_aryptr()) {
1934 const TypeAryPtr* ary = tp->is_aryptr();
1935 const Type* t = ary->elem();
1936
1937 // Determine whether the reference is beyond the header or not, by comparing
1938 // the offset against the offset of the start of the array's data.
1939 // Different array types begin at slightly different offsets (12 vs. 16).
1940 // We choose T_BYTE as an example base type that is least restrictive
1941 // as to alignment, which will therefore produce the smallest
1942 // possible base offset.
1943 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1944 const bool off_beyond_header = (off >= min_base_off);
1945
1946 // Try to constant-fold a stable array element.
1947 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
1948 // Make sure the reference is not into the header and the offset is constant
1949 ciObject* aobj = ary->const_oop();
1950 if (aobj != NULL && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1951 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
1952 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
1953 stable_dimension,
1954 memory_type(), is_unsigned());
1955 if (con_type != NULL) {
1956 return con_type;
1957 }
1958 }
1959 }
1960
1961 // Don't do this for integer types. There is only potential profit if
1962 // the element type t is lower than _type; that is, for int types, if _type is
1963 // more restrictive than t. This only happens here if one is short and the other
1964 // char (both 16 bits), and in those cases we've made an intentional decision
1965 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1966 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1967 //
1968 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1969 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1970 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1971 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1972 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1973 // In fact, that could have been the original type of p1, and p1 could have
1974 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1975 // expression (LShiftL quux 3) independently optimized to the constant 8.
1976 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1977 && (_type->isa_vect() == NULL)
1978 && !ary->is_flat()
1979 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1980 // t might actually be lower than _type, if _type is a unique
1981 // concrete subclass of abstract class t.
1982 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
1983 const Type* jt = t->join_speculative(_type);
1984 // In any case, do not allow the join, per se, to empty out the type.
1985 if (jt->empty() && !t->empty()) {
1986 // This can happen if a interface-typed array narrows to a class type.
1987 jt = _type;
1988 }
1989 #ifdef ASSERT
1990 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1991 // The pointers in the autobox arrays are always non-null
1992 Node* base = adr->in(AddPNode::Base);
1993 if ((base != NULL) && base->is_DecodeN()) {
1994 // Get LoadN node which loads IntegerCache.cache field
1995 base = base->in(1);
1996 }
1997 if ((base != NULL) && base->is_Con()) {
1998 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1999 if ((base_type != NULL) && base_type->is_autobox_cache()) {
2000 // It could be narrow oop
2001 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2002 }
2003 }
2004 }
2005 #endif
2006 return jt;
2007 }
2008 }
2009 } else if (tp->base() == Type::InstPtr) {
2010 assert( off != Type::OffsetBot ||
2011 // arrays can be cast to Objects
2012 !tp->isa_instptr() ||
2013 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2014 // Default value load
2015 tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() ||
2016 // unsafe field access may not have a constant offset
2017 C->has_unsafe_access(),
2018 "Field accesses must be precise" );
2019 // For oop loads, we expect the _type to be precise.
2020
2021 const TypeInstPtr* tinst = tp->is_instptr();
2022 BasicType bt = memory_type();
2023
2024 // Optimize loads from constant fields.
2025 ciObject* const_oop = tinst->const_oop();
2026 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != NULL && const_oop->is_instance()) {
2027 ciType* mirror_type = const_oop->as_instance()->java_mirror_type();
2028 if (mirror_type != NULL) {
2029 const Type* const_oop = NULL;
2030 ciInlineKlass* vk = mirror_type->is_inlinetype() ? mirror_type->as_inline_klass() : NULL;
2031 // Fold default value loads
2032 if (vk != NULL && off == vk->default_value_offset()) {
2033 const_oop = TypeInstPtr::make(vk->default_instance());
2034 }
2035 // Fold class mirror loads
2036 if (off == java_lang_Class::primary_mirror_offset()) {
2037 const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->ref_instance());
2038 } else if (off == java_lang_Class::secondary_mirror_offset()) {
2039 const_oop = (vk == NULL) ? TypePtr::NULL_PTR : TypeInstPtr::make(vk->val_instance());
2040 }
2041 if (const_oop != NULL) {
2042 return (bt == T_NARROWOOP) ? const_oop->make_narrowoop() : const_oop;
2043 }
2044 }
2045 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2046 if (con_type != NULL) {
2047 return con_type;
2048 }
2049 }
2050 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2051 assert(off != Type::OffsetBot ||
2052 !tp->isa_instklassptr() ||
2053 // arrays can be cast to Objects
2054 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2055 // also allow array-loading from the primary supertype
2056 // array during subtype checks
2057 Opcode() == Op_LoadKlass,
2058 "Field accesses must be precise");
2059 // For klass/static loads, we expect the _type to be precise
2060 } else if (tp->base() == Type::RawPtr && !StressReflectiveCode) {
2061 if (adr->is_Load() && off == 0) {
2062 /* With mirrors being an indirect in the Klass*
2063 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2064 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2065 *
2066 * So check the type and klass of the node before the LoadP.
2067 */
2068 Node* adr2 = adr->in(MemNode::Address);
2069 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2070 if (tkls != NULL) {
2071 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2072 ciKlass* klass = tkls->exact_klass();
2073 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2074 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2075 return TypeInstPtr::make(klass->java_mirror());
2076 }
2077 }
2078 } else {
2079 // Check for a load of the default value offset from the InlineKlassFixedBlock:
2080 // LoadI(LoadP(inline_klass, adr_inlineklass_fixed_block_offset), default_value_offset_offset)
2081 intptr_t offset = 0;
2082 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2083 if (base != NULL && base->is_Load() && offset == in_bytes(InlineKlass::default_value_offset_offset())) {
2084 const TypeKlassPtr* tkls = phase->type(base->in(MemNode::Address))->isa_klassptr();
2085 if (tkls != NULL && tkls->is_loaded() && tkls->klass_is_exact() && tkls->exact_klass()->is_inlinetype() &&
2086 tkls->offset() == in_bytes(InstanceKlass::adr_inlineklass_fixed_block_offset())) {
2087 assert(base->Opcode() == Op_LoadP, "must load an oop from klass");
2088 assert(Opcode() == Op_LoadI, "must load an int from fixed block");
2089 return TypeInt::make(tkls->exact_klass()->as_inline_klass()->default_value_offset());
2090 }
2091 }
2092 }
2093 }
2094
2095 const TypeKlassPtr *tkls = tp->isa_klassptr();
2096 if (tkls != NULL) {
2097 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2098 ciKlass* klass = tkls->exact_klass();
2099 // We are loading a field from a Klass metaobject whose identity
2100 // is known at compile time (the type is "exact" or "precise").
2101 // Check for fields we know are maintained as constants by the VM.
2102 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2103 // The field is Klass::_super_check_offset. Return its (constant) value.
2104 // (Folds up type checking code.)
2105 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2106 return TypeInt::make(klass->super_check_offset());
2107 }
2108 // Compute index into primary_supers array
2109 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2110 // Check for overflowing; use unsigned compare to handle the negative case.
2111 if( depth < ciKlass::primary_super_limit() ) {
2112 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2113 // (Folds up type checking code.)
2114 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2115 ciKlass *ss = klass->super_of_depth(depth);
2116 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2117 }
2118 const Type* aift = load_array_final_field(tkls, klass);
2119 if (aift != NULL) return aift;
2120 }
2121
2122 // We can still check if we are loading from the primary_supers array at a
2123 // shallow enough depth. Even though the klass is not exact, entries less
2124 // than or equal to its super depth are correct.
2125 if (tkls->is_loaded()) {
2126 ciKlass* klass = NULL;
2127 if (tkls->isa_instklassptr()) {
2128 klass = tkls->is_instklassptr()->instance_klass();
2129 } else {
2130 int dims;
2131 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2132 if (inner->isa_instklassptr()) {
2133 klass = inner->is_instklassptr()->instance_klass();
2134 klass = ciObjArrayKlass::make(klass, dims);
2135 }
2136 }
2137 if (klass != NULL) {
2138 // Compute index into primary_supers array
2139 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2140 // Check for overflowing; use unsigned compare to handle the negative case.
2141 if (depth < ciKlass::primary_super_limit() &&
2142 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2143 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2144 // (Folds up type checking code.)
2145 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2146 ciKlass *ss = klass->super_of_depth(depth);
2147 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2148 }
2149 }
2150 }
2151
2152 // If the type is enough to determine that the thing is not an array,
2153 // we can give the layout_helper a positive interval type.
2154 // This will help short-circuit some reflective code.
2155 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2156 tkls->isa_instklassptr() && // not directly typed as an array
2157 !tkls->is_instklassptr()->instance_klass()->is_java_lang_Object() // not the supertype of all T[] and specifically not Serializable & Cloneable
2158 ) {
2159 // Note: When interfaces are reliable, we can narrow the interface
2160 // test to (klass != Serializable && klass != Cloneable).
2161 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2162 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2163 // The key property of this type is that it folds up tests
2164 // for array-ness, since it proves that the layout_helper is positive.
2165 // Thus, a generic value like the basic object layout helper works fine.
2166 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2167 }
2168 }
2169
2170 // If we are loading from a freshly-allocated object, produce a zero,
2171 // if the load is provably beyond the header of the object.
2172 // (Also allow a variable load from a fresh array to produce zero.)
2173 const TypeOopPtr *tinst = tp->isa_oopptr();
2174 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
2175 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
2176 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
2177 Node* value = can_see_stored_value(mem,phase);
2178 if (value != NULL && value->is_Con()) {
2179 assert(value->bottom_type()->higher_equal(_type),"sanity");
2180 return value->bottom_type();
2181 }
2182 }
2183
2184 bool is_vect = (_type->isa_vect() != NULL);
2185 if (is_instance && !is_vect) {
2186 // If we have an instance type and our memory input is the
2187 // programs's initial memory state, there is no matching store,
2188 // so just return a zero of the appropriate type -
2189 // except if it is vectorized - then we have no zero constant.
2190 Node *mem = in(MemNode::Memory);
2191 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2192 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2193 return Type::get_zero_type(_type->basic_type());
2194 }
2195 }
2196 Node* alloc = is_new_object_mark_load(phase);
2197 if (alloc != NULL) {
2198 if (EnableValhalla) {
2199 // The mark word may contain property bits (inline, flat, null-free)
2200 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2201 const TypeKlassPtr* tkls = phase->type(klass_node)->is_klassptr();
2202 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2203 return TypeX::make(tkls->exact_klass()->prototype_header().value());
2204 }
2205 } else {
2206 return TypeX::make(markWord::prototype().value());
2207 }
2208 }
2209
2210 return _type;
2211 }
2212
2213 //------------------------------match_edge-------------------------------------
2214 // Do we Match on this edge index or not? Match only the address.
2215 uint LoadNode::match_edge(uint idx) const {
2216 return idx == MemNode::Address;
2217 }
2218
2219 //--------------------------LoadBNode::Ideal--------------------------------------
2220 //
2221 // If the previous store is to the same address as this load,
2222 // and the value stored was larger than a byte, replace this load
2223 // with the value stored truncated to a byte. If no truncation is
2224 // needed, the replacement is done in LoadNode::Identity().
2225 //
2226 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2227 Node* mem = in(MemNode::Memory);
2228 Node* value = can_see_stored_value(mem,phase);
2229 if (value != NULL) {
2230 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2231 if (narrow != value) {
2232 return narrow;
2233 }
2234 }
2235 // Identity call will handle the case where truncation is not needed.
2236 return LoadNode::Ideal(phase, can_reshape);
2237 }
2238
2239 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2240 Node* mem = in(MemNode::Memory);
2241 Node* value = can_see_stored_value(mem,phase);
2242 if (value != NULL && value->is_Con() &&
2243 !value->bottom_type()->higher_equal(_type)) {
2244 // If the input to the store does not fit with the load's result type,
2245 // it must be truncated. We can't delay until Ideal call since
2246 // a singleton Value is needed for split_thru_phi optimization.
2247 int con = value->get_int();
2248 return TypeInt::make((con << 24) >> 24);
2249 }
2250 return LoadNode::Value(phase);
2251 }
2252
2253 //--------------------------LoadUBNode::Ideal-------------------------------------
2254 //
2255 // If the previous store is to the same address as this load,
2256 // and the value stored was larger than a byte, replace this load
2257 // with the value stored truncated to a byte. If no truncation is
2258 // needed, the replacement is done in LoadNode::Identity().
2259 //
2260 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2261 Node* mem = in(MemNode::Memory);
2262 Node* value = can_see_stored_value(mem, phase);
2263 if (value != NULL) {
2264 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2265 if (narrow != value) {
2266 return narrow;
2267 }
2268 }
2269 // Identity call will handle the case where truncation is not needed.
2270 return LoadNode::Ideal(phase, can_reshape);
2271 }
2272
2273 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2274 Node* mem = in(MemNode::Memory);
2275 Node* value = can_see_stored_value(mem,phase);
2276 if (value != NULL && value->is_Con() &&
2277 !value->bottom_type()->higher_equal(_type)) {
2278 // If the input to the store does not fit with the load's result type,
2279 // it must be truncated. We can't delay until Ideal call since
2280 // a singleton Value is needed for split_thru_phi optimization.
2281 int con = value->get_int();
2282 return TypeInt::make(con & 0xFF);
2283 }
2284 return LoadNode::Value(phase);
2285 }
2286
2287 //--------------------------LoadUSNode::Ideal-------------------------------------
2288 //
2289 // If the previous store is to the same address as this load,
2290 // and the value stored was larger than a char, replace this load
2291 // with the value stored truncated to a char. If no truncation is
2292 // needed, the replacement is done in LoadNode::Identity().
2293 //
2294 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2295 Node* mem = in(MemNode::Memory);
2296 Node* value = can_see_stored_value(mem,phase);
2297 if (value != NULL) {
2298 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2299 if (narrow != value) {
2300 return narrow;
2301 }
2302 }
2303 // Identity call will handle the case where truncation is not needed.
2304 return LoadNode::Ideal(phase, can_reshape);
2305 }
2306
2307 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2308 Node* mem = in(MemNode::Memory);
2309 Node* value = can_see_stored_value(mem,phase);
2310 if (value != NULL && value->is_Con() &&
2311 !value->bottom_type()->higher_equal(_type)) {
2312 // If the input to the store does not fit with the load's result type,
2313 // it must be truncated. We can't delay until Ideal call since
2314 // a singleton Value is needed for split_thru_phi optimization.
2315 int con = value->get_int();
2316 return TypeInt::make(con & 0xFFFF);
2317 }
2318 return LoadNode::Value(phase);
2319 }
2320
2321 //--------------------------LoadSNode::Ideal--------------------------------------
2322 //
2323 // If the previous store is to the same address as this load,
2324 // and the value stored was larger than a short, replace this load
2325 // with the value stored truncated to a short. If no truncation is
2326 // needed, the replacement is done in LoadNode::Identity().
2327 //
2328 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2329 Node* mem = in(MemNode::Memory);
2330 Node* value = can_see_stored_value(mem,phase);
2331 if (value != NULL) {
2332 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2333 if (narrow != value) {
2334 return narrow;
2335 }
2336 }
2337 // Identity call will handle the case where truncation is not needed.
2338 return LoadNode::Ideal(phase, can_reshape);
2339 }
2340
2341 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2342 Node* mem = in(MemNode::Memory);
2343 Node* value = can_see_stored_value(mem,phase);
2344 if (value != NULL && value->is_Con() &&
2345 !value->bottom_type()->higher_equal(_type)) {
2346 // If the input to the store does not fit with the load's result type,
2347 // it must be truncated. We can't delay until Ideal call since
2348 // a singleton Value is needed for split_thru_phi optimization.
2349 int con = value->get_int();
2350 return TypeInt::make((con << 16) >> 16);
2351 }
2352 return LoadNode::Value(phase);
2353 }
2354
2355 //=============================================================================
2356 //----------------------------LoadKlassNode::make------------------------------
2357 // Polymorphic factory method:
2358 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at,
2359 const TypeKlassPtr* tk) {
2360 // sanity check the alias category against the created node type
2361 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
2362 assert(adr_type != NULL, "expecting TypeKlassPtr");
2363 #ifdef _LP64
2364 if (adr_type->is_ptr_to_narrowklass()) {
2365 assert(UseCompressedClassPointers, "no compressed klasses");
2366 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2367 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2368 }
2369 #endif
2370 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2371 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
2372 }
2373
2374 //------------------------------Value------------------------------------------
2375 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2376 return klass_value_common(phase);
2377 }
2378
2379 // In most cases, LoadKlassNode does not have the control input set. If the control
2380 // input is set, it must not be removed (by LoadNode::Ideal()).
2381 bool LoadKlassNode::can_remove_control() const {
2382 return false;
2383 }
2384
2385 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2386 // Either input is TOP ==> the result is TOP
2387 const Type *t1 = phase->type( in(MemNode::Memory) );
2388 if (t1 == Type::TOP) return Type::TOP;
2389 Node *adr = in(MemNode::Address);
2390 const Type *t2 = phase->type( adr );
2391 if (t2 == Type::TOP) return Type::TOP;
2392 const TypePtr *tp = t2->is_ptr();
2393 if (TypePtr::above_centerline(tp->ptr()) ||
2394 tp->ptr() == TypePtr::Null) return Type::TOP;
2395
2396 // Return a more precise klass, if possible
2397 const TypeInstPtr *tinst = tp->isa_instptr();
2398 if (tinst != NULL) {
2399 ciInstanceKlass* ik = tinst->instance_klass();
2400 int offset = tinst->offset();
2401 if (ik == phase->C->env()->Class_klass()
2402 && (offset == java_lang_Class::klass_offset() ||
2403 offset == java_lang_Class::array_klass_offset())) {
2404 // We are loading a special hidden field from a Class mirror object,
2405 // the field which points to the VM's Klass metaobject.
2406 bool null_free = false;
2407 ciType* t = tinst->java_mirror_type(&null_free);
2408 // java_mirror_type returns non-null for compile-time Class constants.
2409 if (t != NULL) {
2410 // constant oop => constant klass
2411 if (offset == java_lang_Class::array_klass_offset()) {
2412 if (t->is_void()) {
2413 // We cannot create a void array. Since void is a primitive type return null
2414 // klass. Users of this result need to do a null check on the returned klass.
2415 return TypePtr::NULL_PTR;
2416 }
2417 return TypeKlassPtr::make(ciArrayKlass::make(t, null_free), Type::trust_interfaces);
2418 }
2419 if (!t->is_klass()) {
2420 // a primitive Class (e.g., int.class) has NULL for a klass field
2421 return TypePtr::NULL_PTR;
2422 }
2423 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2424 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2425 }
2426 // non-constant mirror, so we can't tell what's going on
2427 }
2428 if (!tinst->is_loaded())
2429 return _type; // Bail out if not loaded
2430 if (offset == oopDesc::klass_offset_in_bytes()) {
2431 return tinst->as_klass_type(true);
2432 }
2433 }
2434
2435 // Check for loading klass from an array
2436 const TypeAryPtr* tary = tp->isa_aryptr();
2437 if (tary != NULL && tary->elem() != Type::BOTTOM &&
2438 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2439 return tary->as_klass_type(true);
2440 }
2441
2442 // Check for loading klass from an array klass
2443 const TypeKlassPtr *tkls = tp->isa_klassptr();
2444 if (tkls != NULL && !StressReflectiveCode) {
2445 if (!tkls->is_loaded())
2446 return _type; // Bail out if not loaded
2447 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2448 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2449 // // Always returning precise element type is incorrect,
2450 // // e.g., element type could be object and array may contain strings
2451 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2452
2453 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2454 // according to the element type's subclassing.
2455 return tkls->is_aryklassptr()->elem();
2456 }
2457 if (tkls->isa_instklassptr() != NULL && tkls->klass_is_exact() &&
2458 tkls->offset() == in_bytes(Klass::super_offset())) {
2459 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2460 // The field is Klass::_super. Return its (constant) value.
2461 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2462 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2463 }
2464 }
2465
2466 // Bailout case
2467 return LoadNode::Value(phase);
2468 }
2469
2470 //------------------------------Identity---------------------------------------
2471 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2472 // Also feed through the klass in Allocate(...klass...)._klass.
2473 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2474 return klass_identity_common(phase);
2475 }
2476
2477 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2478 Node* x = LoadNode::Identity(phase);
2479 if (x != this) return x;
2480
2481 // Take apart the address into an oop and offset.
2482 // Return 'this' if we cannot.
2483 Node* adr = in(MemNode::Address);
2484 intptr_t offset = 0;
2485 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2486 if (base == NULL) return this;
2487 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2488 if (toop == NULL) return this;
2489
2490 // Step over potential GC barrier for OopHandle resolve
2491 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2492 if (bs->is_gc_barrier_node(base)) {
2493 base = bs->step_over_gc_barrier(base);
2494 }
2495
2496 // We can fetch the klass directly through an AllocateNode.
2497 // This works even if the klass is not constant (clone or newArray).
2498 if (offset == oopDesc::klass_offset_in_bytes()) {
2499 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2500 if (allocated_klass != NULL) {
2501 return allocated_klass;
2502 }
2503 }
2504
2505 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2506 // See inline_native_Class_query for occurrences of these patterns.
2507 // Java Example: x.getClass().isAssignableFrom(y)
2508 //
2509 // This improves reflective code, often making the Class
2510 // mirror go completely dead. (Current exception: Class
2511 // mirrors may appear in debug info, but we could clean them out by
2512 // introducing a new debug info operator for Klass.java_mirror).
2513
2514 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2515 && offset == java_lang_Class::klass_offset()) {
2516 if (base->is_Load()) {
2517 Node* base2 = base->in(MemNode::Address);
2518 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2519 Node* adr2 = base2->in(MemNode::Address);
2520 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2521 if (tkls != NULL && !tkls->empty()
2522 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2523 && adr2->is_AddP()
2524 ) {
2525 int mirror_field = in_bytes(Klass::java_mirror_offset());
2526 if (tkls->offset() == mirror_field) {
2527 return adr2->in(AddPNode::Base);
2528 }
2529 }
2530 }
2531 }
2532 }
2533
2534 return this;
2535 }
2536
2537
2538 //------------------------------Value------------------------------------------
2539 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2540 const Type *t = klass_value_common(phase);
2541 if (t == Type::TOP)
2542 return t;
2543
2544 return t->make_narrowklass();
2545 }
2546
2547 //------------------------------Identity---------------------------------------
2548 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2549 // Also feed through the klass in Allocate(...klass...)._klass.
2550 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2551 Node *x = klass_identity_common(phase);
2552
2553 const Type *t = phase->type( x );
2554 if( t == Type::TOP ) return x;
2555 if( t->isa_narrowklass()) return x;
2556 assert (!t->isa_narrowoop(), "no narrow oop here");
2557
2558 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2559 }
2560
2561 //------------------------------Value-----------------------------------------
2562 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2563 // Either input is TOP ==> the result is TOP
2564 const Type *t1 = phase->type( in(MemNode::Memory) );
2565 if( t1 == Type::TOP ) return Type::TOP;
2566 Node *adr = in(MemNode::Address);
2567 const Type *t2 = phase->type( adr );
2568 if( t2 == Type::TOP ) return Type::TOP;
2569 const TypePtr *tp = t2->is_ptr();
2570 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2571 const TypeAryPtr *tap = tp->isa_aryptr();
2572 if( !tap ) return _type;
2573 return tap->size();
2574 }
2575
2576 //-------------------------------Ideal---------------------------------------
2577 // Feed through the length in AllocateArray(...length...)._length.
2578 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2579 Node* p = MemNode::Ideal_common(phase, can_reshape);
2580 if (p) return (p == NodeSentinel) ? NULL : p;
2581
2582 // Take apart the address into an oop and offset.
2583 // Return 'this' if we cannot.
2584 Node* adr = in(MemNode::Address);
2585 intptr_t offset = 0;
2586 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2587 if (base == NULL) return NULL;
2588 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2589 if (tary == NULL) return NULL;
2590
2591 // We can fetch the length directly through an AllocateArrayNode.
2592 // This works even if the length is not constant (clone or newArray).
2593 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2594 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2595 if (alloc != NULL) {
2596 Node* allocated_length = alloc->Ideal_length();
2597 Node* len = alloc->make_ideal_length(tary, phase);
2598 if (allocated_length != len) {
2599 // New CastII improves on this.
2600 return len;
2601 }
2602 }
2603 }
2604
2605 return NULL;
2606 }
2607
2608 //------------------------------Identity---------------------------------------
2609 // Feed through the length in AllocateArray(...length...)._length.
2610 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2611 Node* x = LoadINode::Identity(phase);
2612 if (x != this) return x;
2613
2614 // Take apart the address into an oop and offset.
2615 // Return 'this' if we cannot.
2616 Node* adr = in(MemNode::Address);
2617 intptr_t offset = 0;
2618 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2619 if (base == NULL) return this;
2620 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2621 if (tary == NULL) return this;
2622
2623 // We can fetch the length directly through an AllocateArrayNode.
2624 // This works even if the length is not constant (clone or newArray).
2625 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2626 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2627 if (alloc != NULL) {
2628 Node* allocated_length = alloc->Ideal_length();
2629 // Do not allow make_ideal_length to allocate a CastII node.
2630 Node* len = alloc->make_ideal_length(tary, phase, false);
2631 if (allocated_length == len) {
2632 // Return allocated_length only if it would not be improved by a CastII.
2633 return allocated_length;
2634 }
2635 }
2636 }
2637
2638 return this;
2639
2640 }
2641
2642 //=============================================================================
2643 //---------------------------StoreNode::make-----------------------------------
2644 // Polymorphic factory method:
2645 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo, bool require_atomic_access) {
2646 assert((mo == unordered || mo == release), "unexpected");
2647 Compile* C = gvn.C;
2648 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2649 ctl != NULL, "raw memory operations should have control edge");
2650
2651 switch (bt) {
2652 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2653 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2654 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2655 case T_CHAR:
2656 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2657 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2658 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2659 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2660 case T_METADATA:
2661 case T_ADDRESS:
2662 case T_PRIMITIVE_OBJECT:
2663 case T_OBJECT:
2664 #ifdef _LP64
2665 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2666 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2667 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2668 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2669 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2670 adr->bottom_type()->isa_rawptr())) {
2671 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2672 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2673 }
2674 #endif
2675 {
2676 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2677 }
2678 default:
2679 ShouldNotReachHere();
2680 return (StoreNode*)NULL;
2681 }
2682 }
2683
2684 //--------------------------bottom_type----------------------------------------
2685 const Type *StoreNode::bottom_type() const {
2686 return Type::MEMORY;
2687 }
2688
2689 //------------------------------hash-------------------------------------------
2690 uint StoreNode::hash() const {
2691 // unroll addition of interesting fields
2692 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2693
2694 // Since they are not commoned, do not hash them:
2695 return NO_HASH;
2696 }
2697
2698 //------------------------------Ideal------------------------------------------
2699 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2700 // When a store immediately follows a relevant allocation/initialization,
2701 // try to capture it into the initialization, or hoist it above.
2702 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2703 Node* p = MemNode::Ideal_common(phase, can_reshape);
2704 if (p) return (p == NodeSentinel) ? NULL : p;
2705
2706 Node* mem = in(MemNode::Memory);
2707 Node* address = in(MemNode::Address);
2708 Node* value = in(MemNode::ValueIn);
2709 // Back-to-back stores to same address? Fold em up. Generally
2710 // unsafe if I have intervening uses... Also disallowed for StoreCM
2711 // since they must follow each StoreP operation. Redundant StoreCMs
2712 // are eliminated just before matching in final_graph_reshape.
2713 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
2714 Node* st = mem;
2715 // If Store 'st' has more than one use, we cannot fold 'st' away.
2716 // For example, 'st' might be the final state at a conditional
2717 // return. Or, 'st' might be used by some node which is live at
2718 // the same time 'st' is live, which might be unschedulable. So,
2719 // require exactly ONE user until such time as we clone 'mem' for
2720 // each of 'mem's uses (thus making the exactly-1-user-rule hold
2721 // true).
2722 while (st->is_Store() && st->outcnt() == 1 && st->Opcode() != Op_StoreCM) {
2723 // Looking at a dead closed cycle of memory?
2724 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2725 assert(Opcode() == st->Opcode() ||
2726 st->Opcode() == Op_StoreVector ||
2727 Opcode() == Op_StoreVector ||
2728 st->Opcode() == Op_StoreVectorScatter ||
2729 Opcode() == Op_StoreVectorScatter ||
2730 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
2731 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
2732 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
2733 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
2734 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
2735 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
2736
2737 if (st->in(MemNode::Address)->eqv_uncast(address) &&
2738 st->as_Store()->memory_size() <= this->memory_size()) {
2739 Node* use = st->raw_out(0);
2740 if (phase->is_IterGVN()) {
2741 phase->is_IterGVN()->rehash_node_delayed(use);
2742 }
2743 // It's OK to do this in the parser, since DU info is always accurate,
2744 // and the parser always refers to nodes via SafePointNode maps.
2745 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
2746 return this;
2747 }
2748 st = st->in(MemNode::Memory);
2749 }
2750 }
2751
2752
2753 // Capture an unaliased, unconditional, simple store into an initializer.
2754 // Or, if it is independent of the allocation, hoist it above the allocation.
2755 if (ReduceFieldZeroing && /*can_reshape &&*/
2756 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2757 InitializeNode* init = mem->in(0)->as_Initialize();
2758 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2759 if (offset > 0) {
2760 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2761 // If the InitializeNode captured me, it made a raw copy of me,
2762 // and I need to disappear.
2763 if (moved != NULL) {
2764 // %%% hack to ensure that Ideal returns a new node:
2765 mem = MergeMemNode::make(mem);
2766 return mem; // fold me away
2767 }
2768 }
2769 }
2770
2771 // Fold reinterpret cast into memory operation:
2772 // StoreX mem (MoveY2X v) => StoreY mem v
2773 if (value->is_Move()) {
2774 const Type* vt = value->in(1)->bottom_type();
2775 if (has_reinterpret_variant(vt)) {
2776 if (phase->C->post_loop_opts_phase()) {
2777 return convert_to_reinterpret_store(*phase, value->in(1), vt);
2778 } else {
2779 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
2780 }
2781 }
2782 }
2783
2784 return NULL; // No further progress
2785 }
2786
2787 //------------------------------Value-----------------------------------------
2788 const Type* StoreNode::Value(PhaseGVN* phase) const {
2789 // Either input is TOP ==> the result is TOP
2790 const Type *t1 = phase->type( in(MemNode::Memory) );
2791 if( t1 == Type::TOP ) return Type::TOP;
2792 const Type *t2 = phase->type( in(MemNode::Address) );
2793 if( t2 == Type::TOP ) return Type::TOP;
2794 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2795 if( t3 == Type::TOP ) return Type::TOP;
2796 return Type::MEMORY;
2797 }
2798
2799 //------------------------------Identity---------------------------------------
2800 // Remove redundant stores:
2801 // Store(m, p, Load(m, p)) changes to m.
2802 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2803 Node* StoreNode::Identity(PhaseGVN* phase) {
2804 Node* mem = in(MemNode::Memory);
2805 Node* adr = in(MemNode::Address);
2806 Node* val = in(MemNode::ValueIn);
2807
2808 Node* result = this;
2809
2810 // Load then Store? Then the Store is useless
2811 if (val->is_Load() &&
2812 val->in(MemNode::Address)->eqv_uncast(adr) &&
2813 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2814 val->as_Load()->store_Opcode() == Opcode()) {
2815 result = mem;
2816 }
2817
2818 // Two stores in a row of the same value?
2819 if (result == this &&
2820 mem->is_Store() &&
2821 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2822 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2823 mem->Opcode() == Opcode()) {
2824 result = mem;
2825 }
2826
2827 // Store of zero anywhere into a freshly-allocated object?
2828 // Then the store is useless.
2829 // (It must already have been captured by the InitializeNode.)
2830 if (result == this && ReduceFieldZeroing) {
2831 // a newly allocated object is already all-zeroes everywhere
2832 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
2833 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::DefaultValue) == val)) {
2834 result = mem;
2835 }
2836
2837 if (result == this && phase->type(val)->is_zero_type()) {
2838 // the store may also apply to zero-bits in an earlier object
2839 Node* prev_mem = find_previous_store(phase);
2840 // Steps (a), (b): Walk past independent stores to find an exact match.
2841 if (prev_mem != NULL) {
2842 Node* prev_val = can_see_stored_value(prev_mem, phase);
2843 if (prev_val != NULL && prev_val == val) {
2844 // prev_val and val might differ by a cast; it would be good
2845 // to keep the more informative of the two.
2846 result = mem;
2847 }
2848 }
2849 }
2850 }
2851
2852 PhaseIterGVN* igvn = phase->is_IterGVN();
2853 if (result != this && igvn != NULL) {
2854 MemBarNode* trailing = trailing_membar();
2855 if (trailing != NULL) {
2856 #ifdef ASSERT
2857 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
2858 assert(t_oop == NULL || t_oop->is_known_instance_field(), "only for non escaping objects");
2859 #endif
2860 trailing->remove(igvn);
2861 }
2862 }
2863
2864 return result;
2865 }
2866
2867 //------------------------------match_edge-------------------------------------
2868 // Do we Match on this edge index or not? Match only memory & value
2869 uint StoreNode::match_edge(uint idx) const {
2870 return idx == MemNode::Address || idx == MemNode::ValueIn;
2871 }
2872
2873 //------------------------------cmp--------------------------------------------
2874 // Do not common stores up together. They generally have to be split
2875 // back up anyways, so do not bother.
2876 bool StoreNode::cmp( const Node &n ) const {
2877 return (&n == this); // Always fail except on self
2878 }
2879
2880 //------------------------------Ideal_masked_input-----------------------------
2881 // Check for a useless mask before a partial-word store
2882 // (StoreB ... (AndI valIn conIa) )
2883 // If (conIa & mask == mask) this simplifies to
2884 // (StoreB ... (valIn) )
2885 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2886 Node *val = in(MemNode::ValueIn);
2887 if( val->Opcode() == Op_AndI ) {
2888 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2889 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2890 set_req_X(MemNode::ValueIn, val->in(1), phase);
2891 return this;
2892 }
2893 }
2894 return NULL;
2895 }
2896
2897
2898 //------------------------------Ideal_sign_extended_input----------------------
2899 // Check for useless sign-extension before a partial-word store
2900 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2901 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2902 // (StoreB ... (valIn) )
2903 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2904 Node *val = in(MemNode::ValueIn);
2905 if( val->Opcode() == Op_RShiftI ) {
2906 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2907 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2908 Node *shl = val->in(1);
2909 if( shl->Opcode() == Op_LShiftI ) {
2910 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2911 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2912 set_req_X(MemNode::ValueIn, shl->in(1), phase);
2913 return this;
2914 }
2915 }
2916 }
2917 }
2918 return NULL;
2919 }
2920
2921 //------------------------------value_never_loaded-----------------------------------
2922 // Determine whether there are any possible loads of the value stored.
2923 // For simplicity, we actually check if there are any loads from the
2924 // address stored to, not just for loads of the value stored by this node.
2925 //
2926 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2927 Node *adr = in(Address);
2928 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2929 if (adr_oop == NULL)
2930 return false;
2931 if (!adr_oop->is_known_instance_field())
2932 return false; // if not a distinct instance, there may be aliases of the address
2933 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2934 Node *use = adr->fast_out(i);
2935 if (use->is_Load() || use->is_LoadStore()) {
2936 return false;
2937 }
2938 }
2939 return true;
2940 }
2941
2942 MemBarNode* StoreNode::trailing_membar() const {
2943 if (is_release()) {
2944 MemBarNode* trailing_mb = NULL;
2945 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
2946 Node* u = fast_out(i);
2947 if (u->is_MemBar()) {
2948 if (u->as_MemBar()->trailing_store()) {
2949 assert(u->Opcode() == Op_MemBarVolatile, "");
2950 assert(trailing_mb == NULL, "only one");
2951 trailing_mb = u->as_MemBar();
2952 #ifdef ASSERT
2953 Node* leading = u->as_MemBar()->leading_membar();
2954 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
2955 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
2956 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
2957 #endif
2958 } else {
2959 assert(u->as_MemBar()->standalone(), "");
2960 }
2961 }
2962 }
2963 return trailing_mb;
2964 }
2965 return NULL;
2966 }
2967
2968
2969 //=============================================================================
2970 //------------------------------Ideal------------------------------------------
2971 // If the store is from an AND mask that leaves the low bits untouched, then
2972 // we can skip the AND operation. If the store is from a sign-extension
2973 // (a left shift, then right shift) we can skip both.
2974 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2975 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2976 if( progress != NULL ) return progress;
2977
2978 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2979 if( progress != NULL ) return progress;
2980
2981 // Finally check the default case
2982 return StoreNode::Ideal(phase, can_reshape);
2983 }
2984
2985 //=============================================================================
2986 //------------------------------Ideal------------------------------------------
2987 // If the store is from an AND mask that leaves the low bits untouched, then
2988 // we can skip the AND operation
2989 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2990 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2991 if( progress != NULL ) return progress;
2992
2993 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2994 if( progress != NULL ) return progress;
2995
2996 // Finally check the default case
2997 return StoreNode::Ideal(phase, can_reshape);
2998 }
2999
3000 //=============================================================================
3001 //------------------------------Identity---------------------------------------
3002 Node* StoreCMNode::Identity(PhaseGVN* phase) {
3003 // No need to card mark when storing a null ptr
3004 Node* my_store = in(MemNode::OopStore);
3005 if (my_store->is_Store()) {
3006 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
3007 if( t1 == TypePtr::NULL_PTR ) {
3008 return in(MemNode::Memory);
3009 }
3010 }
3011 return this;
3012 }
3013
3014 //=============================================================================
3015 //------------------------------Ideal---------------------------------------
3016 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
3017 Node* progress = StoreNode::Ideal(phase, can_reshape);
3018 if (progress != NULL) return progress;
3019
3020 Node* my_store = in(MemNode::OopStore);
3021 if (my_store->is_MergeMem()) {
3022 if (oop_alias_idx() != phase->C->get_alias_index(TypeAryPtr::INLINES) ||
3023 phase->C->flattened_accesses_share_alias()) {
3024 // The alias that was recorded is no longer accurate enough.
3025 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
3026 set_req_X(MemNode::OopStore, mem, phase);
3027 return this;
3028 }
3029 }
3030
3031 return NULL;
3032 }
3033
3034 //------------------------------Value-----------------------------------------
3035 const Type* StoreCMNode::Value(PhaseGVN* phase) const {
3036 // Either input is TOP ==> the result is TOP (checked in StoreNode::Value).
3037 // If extra input is TOP ==> the result is TOP
3038 const Type* t = phase->type(in(MemNode::OopStore));
3039 if (t == Type::TOP) {
3040 return Type::TOP;
3041 }
3042 return StoreNode::Value(phase);
3043 }
3044
3045
3046 //=============================================================================
3047 //----------------------------------SCMemProjNode------------------------------
3048 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
3049 {
3050 if (in(0) == NULL || phase->type(in(0)) == Type::TOP) {
3051 return Type::TOP;
3052 }
3053 return bottom_type();
3054 }
3055
3056 //=============================================================================
3057 //----------------------------------LoadStoreNode------------------------------
3058 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
3059 : Node(required),
3060 _type(rt),
3061 _adr_type(at),
3062 _barrier_data(0)
3063 {
3064 init_req(MemNode::Control, c );
3065 init_req(MemNode::Memory , mem);
3066 init_req(MemNode::Address, adr);
3067 init_req(MemNode::ValueIn, val);
3068 init_class_id(Class_LoadStore);
3069 }
3070
3071 //------------------------------Value-----------------------------------------
3072 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
3073 // Either input is TOP ==> the result is TOP
3074 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
3075 return Type::TOP;
3076 }
3077 const Type* t = phase->type(in(MemNode::Memory));
3078 if (t == Type::TOP) {
3079 return Type::TOP;
3080 }
3081 t = phase->type(in(MemNode::Address));
3082 if (t == Type::TOP) {
3083 return Type::TOP;
3084 }
3085 t = phase->type(in(MemNode::ValueIn));
3086 if (t == Type::TOP) {
3087 return Type::TOP;
3088 }
3089 return bottom_type();
3090 }
3091
3092 uint LoadStoreNode::ideal_reg() const {
3093 return _type->ideal_reg();
3094 }
3095
3096 bool LoadStoreNode::result_not_used() const {
3097 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
3098 Node *x = fast_out(i);
3099 if (x->Opcode() == Op_SCMemProj) continue;
3100 return false;
3101 }
3102 return true;
3103 }
3104
3105 MemBarNode* LoadStoreNode::trailing_membar() const {
3106 MemBarNode* trailing = NULL;
3107 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3108 Node* u = fast_out(i);
3109 if (u->is_MemBar()) {
3110 if (u->as_MemBar()->trailing_load_store()) {
3111 assert(u->Opcode() == Op_MemBarAcquire, "");
3112 assert(trailing == NULL, "only one");
3113 trailing = u->as_MemBar();
3114 #ifdef ASSERT
3115 Node* leading = trailing->leading_membar();
3116 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
3117 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
3118 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
3119 #endif
3120 } else {
3121 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
3122 }
3123 }
3124 }
3125
3126 return trailing;
3127 }
3128
3129 uint LoadStoreNode::size_of() const { return sizeof(*this); }
3130
3131 //=============================================================================
3132 //----------------------------------LoadStoreConditionalNode--------------------
3133 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
3134 init_req(ExpectedIn, ex );
3135 }
3136
3137 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
3138 // Either input is TOP ==> the result is TOP
3139 const Type* t = phase->type(in(ExpectedIn));
3140 if (t == Type::TOP) {
3141 return Type::TOP;
3142 }
3143 return LoadStoreNode::Value(phase);
3144 }
3145
3146 //=============================================================================
3147 //-------------------------------adr_type--------------------------------------
3148 const TypePtr* ClearArrayNode::adr_type() const {
3149 Node *adr = in(3);
3150 if (adr == NULL) return NULL; // node is dead
3151 return MemNode::calculate_adr_type(adr->bottom_type());
3152 }
3153
3154 //------------------------------match_edge-------------------------------------
3155 // Do we Match on this edge index or not? Do not match memory
3156 uint ClearArrayNode::match_edge(uint idx) const {
3157 return idx > 1;
3158 }
3159
3160 //------------------------------Identity---------------------------------------
3161 // Clearing a zero length array does nothing
3162 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
3163 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
3164 }
3165
3166 //------------------------------Idealize---------------------------------------
3167 // Clearing a short array is faster with stores
3168 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3169 // Already know this is a large node, do not try to ideal it
3170 if (_is_large) return NULL;
3171
3172 const int unit = BytesPerLong;
3173 const TypeX* t = phase->type(in(2))->isa_intptr_t();
3174 if (!t) return NULL;
3175 if (!t->is_con()) return NULL;
3176 intptr_t raw_count = t->get_con();
3177 intptr_t size = raw_count;
3178 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
3179 // Clearing nothing uses the Identity call.
3180 // Negative clears are possible on dead ClearArrays
3181 // (see jck test stmt114.stmt11402.val).
3182 if (size <= 0 || size % unit != 0) return NULL;
3183 intptr_t count = size / unit;
3184 // Length too long; communicate this to matchers and assemblers.
3185 // Assemblers are responsible to produce fast hardware clears for it.
3186 if (size > InitArrayShortSize) {
3187 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
3188 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
3189 return NULL;
3190 }
3191 if (!IdealizeClearArrayNode) return NULL;
3192 Node *mem = in(1);
3193 if( phase->type(mem)==Type::TOP ) return NULL;
3194 Node *adr = in(3);
3195 const Type* at = phase->type(adr);
3196 if( at==Type::TOP ) return NULL;
3197 const TypePtr* atp = at->isa_ptr();
3198 // adjust atp to be the correct array element address type
3199 if (atp == NULL) atp = TypePtr::BOTTOM;
3200 else atp = atp->add_offset(Type::OffsetBot);
3201 // Get base for derived pointer purposes
3202 if( adr->Opcode() != Op_AddP ) Unimplemented();
3203 Node *base = adr->in(1);
3204
3205 Node *val = in(4);
3206 Node *off = phase->MakeConX(BytesPerLong);
3207 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3208 count--;
3209 while( count-- ) {
3210 mem = phase->transform(mem);
3211 adr = phase->transform(new AddPNode(base,adr,off));
3212 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
3213 }
3214 return mem;
3215 }
3216
3217 //----------------------------step_through----------------------------------
3218 // Return allocation input memory edge if it is different instance
3219 // or itself if it is the one we are looking for.
3220 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
3221 Node* n = *np;
3222 assert(n->is_ClearArray(), "sanity");
3223 intptr_t offset;
3224 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
3225 // This method is called only before Allocate nodes are expanded
3226 // during macro nodes expansion. Before that ClearArray nodes are
3227 // only generated in PhaseMacroExpand::generate_arraycopy() (before
3228 // Allocate nodes are expanded) which follows allocations.
3229 assert(alloc != NULL, "should have allocation");
3230 if (alloc->_idx == instance_id) {
3231 // Can not bypass initialization of the instance we are looking for.
3232 return false;
3233 }
3234 // Otherwise skip it.
3235 InitializeNode* init = alloc->initialization();
3236 if (init != NULL)
3237 *np = init->in(TypeFunc::Memory);
3238 else
3239 *np = alloc->in(TypeFunc::Memory);
3240 return true;
3241 }
3242
3243 //----------------------------clear_memory-------------------------------------
3244 // Generate code to initialize object storage to zero.
3245 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3246 Node* val,
3247 Node* raw_val,
3248 intptr_t start_offset,
3249 Node* end_offset,
3250 PhaseGVN* phase) {
3251 intptr_t offset = start_offset;
3252
3253 int unit = BytesPerLong;
3254 if ((offset % unit) != 0) {
3255 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
3256 adr = phase->transform(adr);
3257 const TypePtr* atp = TypeRawPtr::BOTTOM;
3258 if (val != NULL) {
3259 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3260 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3261 } else {
3262 assert(raw_val == NULL, "val may not be null");
3263 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3264 }
3265 mem = phase->transform(mem);
3266 offset += BytesPerInt;
3267 }
3268 assert((offset % unit) == 0, "");
3269
3270 // Initialize the remaining stuff, if any, with a ClearArray.
3271 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
3272 }
3273
3274 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3275 Node* raw_val,
3276 Node* start_offset,
3277 Node* end_offset,
3278 PhaseGVN* phase) {
3279 if (start_offset == end_offset) {
3280 // nothing to do
3281 return mem;
3282 }
3283
3284 int unit = BytesPerLong;
3285 Node* zbase = start_offset;
3286 Node* zend = end_offset;
3287
3288 // Scale to the unit required by the CPU:
3289 if (!Matcher::init_array_count_is_in_bytes) {
3290 Node* shift = phase->intcon(exact_log2(unit));
3291 zbase = phase->transform(new URShiftXNode(zbase, shift) );
3292 zend = phase->transform(new URShiftXNode(zend, shift) );
3293 }
3294
3295 // Bulk clear double-words
3296 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
3297 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
3298 if (raw_val == NULL) {
3299 raw_val = phase->MakeConX(0);
3300 }
3301 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
3302 return phase->transform(mem);
3303 }
3304
3305 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
3306 Node* val,
3307 Node* raw_val,
3308 intptr_t start_offset,
3309 intptr_t end_offset,
3310 PhaseGVN* phase) {
3311 if (start_offset == end_offset) {
3312 // nothing to do
3313 return mem;
3314 }
3315
3316 assert((end_offset % BytesPerInt) == 0, "odd end offset");
3317 intptr_t done_offset = end_offset;
3318 if ((done_offset % BytesPerLong) != 0) {
3319 done_offset -= BytesPerInt;
3320 }
3321 if (done_offset > start_offset) {
3322 mem = clear_memory(ctl, mem, dest, val, raw_val,
3323 start_offset, phase->MakeConX(done_offset), phase);
3324 }
3325 if (done_offset < end_offset) { // emit the final 32-bit store
3326 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
3327 adr = phase->transform(adr);
3328 const TypePtr* atp = TypeRawPtr::BOTTOM;
3329 if (val != NULL) {
3330 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
3331 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
3332 } else {
3333 assert(raw_val == NULL, "val may not be null");
3334 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
3335 }
3336 mem = phase->transform(mem);
3337 done_offset += BytesPerInt;
3338 }
3339 assert(done_offset == end_offset, "");
3340 return mem;
3341 }
3342
3343 //=============================================================================
3344 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
3345 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
3346 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
3347 #ifdef ASSERT
3348 , _pair_idx(0)
3349 #endif
3350 {
3351 init_class_id(Class_MemBar);
3352 Node* top = C->top();
3353 init_req(TypeFunc::I_O,top);
3354 init_req(TypeFunc::FramePtr,top);
3355 init_req(TypeFunc::ReturnAdr,top);
3356 if (precedent != NULL)
3357 init_req(TypeFunc::Parms, precedent);
3358 }
3359
3360 //------------------------------cmp--------------------------------------------
3361 uint MemBarNode::hash() const { return NO_HASH; }
3362 bool MemBarNode::cmp( const Node &n ) const {
3363 return (&n == this); // Always fail except on self
3364 }
3365
3366 //------------------------------make-------------------------------------------
3367 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
3368 switch (opcode) {
3369 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
3370 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
3371 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
3372 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
3373 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
3374 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
3375 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
3376 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
3377 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
3378 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
3379 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
3380 case Op_Initialize: return new InitializeNode(C, atp, pn);
3381 default: ShouldNotReachHere(); return NULL;
3382 }
3383 }
3384
3385 void MemBarNode::remove(PhaseIterGVN *igvn) {
3386 if (outcnt() != 2) {
3387 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
3388 assert(outcnt() == 1, "Only control then");
3389 }
3390 if (trailing_store() || trailing_load_store()) {
3391 MemBarNode* leading = leading_membar();
3392 if (leading != NULL) {
3393 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
3394 leading->remove(igvn);
3395 }
3396 }
3397 if (proj_out_or_null(TypeFunc::Memory) != NULL) {
3398 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
3399 }
3400 if (proj_out_or_null(TypeFunc::Control) != NULL) {
3401 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
3402 }
3403 }
3404
3405 //------------------------------Ideal------------------------------------------
3406 // Return a node which is more "ideal" than the current node. Strip out
3407 // control copies
3408 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3409 if (remove_dead_region(phase, can_reshape)) return this;
3410 // Don't bother trying to transform a dead node
3411 if (in(0) && in(0)->is_top()) {
3412 return NULL;
3413 }
3414
3415 bool progress = false;
3416 // Eliminate volatile MemBars for scalar replaced objects.
3417 if (can_reshape && req() == (Precedent+1)) {
3418 bool eliminate = false;
3419 int opc = Opcode();
3420 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
3421 // Volatile field loads and stores.
3422 Node* my_mem = in(MemBarNode::Precedent);
3423 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
3424 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
3425 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
3426 // replace this Precedent (decodeN) with the Load instead.
3427 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
3428 Node* load_node = my_mem->in(1);
3429 set_req(MemBarNode::Precedent, load_node);
3430 phase->is_IterGVN()->_worklist.push(my_mem);
3431 my_mem = load_node;
3432 } else {
3433 assert(my_mem->unique_out() == this, "sanity");
3434 del_req(Precedent);
3435 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
3436 my_mem = NULL;
3437 }
3438 progress = true;
3439 }
3440 if (my_mem != NULL && my_mem->is_Mem()) {
3441 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
3442 // Check for scalar replaced object reference.
3443 if( t_oop != NULL && t_oop->is_known_instance_field() &&
3444 t_oop->offset() != Type::OffsetBot &&
3445 t_oop->offset() != Type::OffsetTop) {
3446 eliminate = true;
3447 }
3448 }
3449 } else if (opc == Op_MemBarRelease) {
3450 // Final field stores.
3451 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
3452 if ((alloc != NULL) && alloc->is_Allocate() &&
3453 alloc->as_Allocate()->does_not_escape_thread()) {
3454 // The allocated object does not escape.
3455 eliminate = true;
3456 }
3457 }
3458 if (eliminate) {
3459 // Replace MemBar projections by its inputs.
3460 PhaseIterGVN* igvn = phase->is_IterGVN();
3461 remove(igvn);
3462 // Must return either the original node (now dead) or a new node
3463 // (Do not return a top here, since that would break the uniqueness of top.)
3464 return new ConINode(TypeInt::ZERO);
3465 }
3466 }
3467 return progress ? this : NULL;
3468 }
3469
3470 //------------------------------Value------------------------------------------
3471 const Type* MemBarNode::Value(PhaseGVN* phase) const {
3472 if( !in(0) ) return Type::TOP;
3473 if( phase->type(in(0)) == Type::TOP )
3474 return Type::TOP;
3475 return TypeTuple::MEMBAR;
3476 }
3477
3478 //------------------------------match------------------------------------------
3479 // Construct projections for memory.
3480 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
3481 switch (proj->_con) {
3482 case TypeFunc::Control:
3483 case TypeFunc::Memory:
3484 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
3485 }
3486 ShouldNotReachHere();
3487 return NULL;
3488 }
3489
3490 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3491 trailing->_kind = TrailingStore;
3492 leading->_kind = LeadingStore;
3493 #ifdef ASSERT
3494 trailing->_pair_idx = leading->_idx;
3495 leading->_pair_idx = leading->_idx;
3496 #endif
3497 }
3498
3499 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
3500 trailing->_kind = TrailingLoadStore;
3501 leading->_kind = LeadingLoadStore;
3502 #ifdef ASSERT
3503 trailing->_pair_idx = leading->_idx;
3504 leading->_pair_idx = leading->_idx;
3505 #endif
3506 }
3507
3508 MemBarNode* MemBarNode::trailing_membar() const {
3509 ResourceMark rm;
3510 Node* trailing = (Node*)this;
3511 VectorSet seen;
3512 Node_Stack multis(0);
3513 do {
3514 Node* c = trailing;
3515 uint i = 0;
3516 do {
3517 trailing = NULL;
3518 for (; i < c->outcnt(); i++) {
3519 Node* next = c->raw_out(i);
3520 if (next != c && next->is_CFG()) {
3521 if (c->is_MultiBranch()) {
3522 if (multis.node() == c) {
3523 multis.set_index(i+1);
3524 } else {
3525 multis.push(c, i+1);
3526 }
3527 }
3528 trailing = next;
3529 break;
3530 }
3531 }
3532 if (trailing != NULL && !seen.test_set(trailing->_idx)) {
3533 break;
3534 }
3535 while (multis.size() > 0) {
3536 c = multis.node();
3537 i = multis.index();
3538 if (i < c->req()) {
3539 break;
3540 }
3541 multis.pop();
3542 }
3543 } while (multis.size() > 0);
3544 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
3545
3546 MemBarNode* mb = trailing->as_MemBar();
3547 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
3548 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
3549 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
3550 return mb;
3551 }
3552
3553 MemBarNode* MemBarNode::leading_membar() const {
3554 ResourceMark rm;
3555 VectorSet seen;
3556 Node_Stack regions(0);
3557 Node* leading = in(0);
3558 while (leading != NULL && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
3559 while (leading == NULL || leading->is_top() || seen.test_set(leading->_idx)) {
3560 leading = NULL;
3561 while (regions.size() > 0 && leading == NULL) {
3562 Node* r = regions.node();
3563 uint i = regions.index();
3564 if (i < r->req()) {
3565 leading = r->in(i);
3566 regions.set_index(i+1);
3567 } else {
3568 regions.pop();
3569 }
3570 }
3571 if (leading == NULL) {
3572 assert(regions.size() == 0, "all paths should have been tried");
3573 return NULL;
3574 }
3575 }
3576 if (leading->is_Region()) {
3577 regions.push(leading, 2);
3578 leading = leading->in(1);
3579 } else {
3580 leading = leading->in(0);
3581 }
3582 }
3583 #ifdef ASSERT
3584 Unique_Node_List wq;
3585 wq.push((Node*)this);
3586 uint found = 0;
3587 for (uint i = 0; i < wq.size(); i++) {
3588 Node* n = wq.at(i);
3589 if (n->is_Region()) {
3590 for (uint j = 1; j < n->req(); j++) {
3591 Node* in = n->in(j);
3592 if (in != NULL && !in->is_top()) {
3593 wq.push(in);
3594 }
3595 }
3596 } else {
3597 if (n->is_MemBar() && n->as_MemBar()->leading()) {
3598 assert(n == leading, "consistency check failed");
3599 found++;
3600 } else {
3601 Node* in = n->in(0);
3602 if (in != NULL && !in->is_top()) {
3603 wq.push(in);
3604 }
3605 }
3606 }
3607 }
3608 assert(found == 1 || (found == 0 && leading == NULL), "consistency check failed");
3609 #endif
3610 if (leading == NULL) {
3611 return NULL;
3612 }
3613 MemBarNode* mb = leading->as_MemBar();
3614 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
3615 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
3616 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
3617 return mb;
3618 }
3619
3620
3621 //===========================InitializeNode====================================
3622 // SUMMARY:
3623 // This node acts as a memory barrier on raw memory, after some raw stores.
3624 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
3625 // The Initialize can 'capture' suitably constrained stores as raw inits.
3626 // It can coalesce related raw stores into larger units (called 'tiles').
3627 // It can avoid zeroing new storage for memory units which have raw inits.
3628 // At macro-expansion, it is marked 'complete', and does not optimize further.
3629 //
3630 // EXAMPLE:
3631 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
3632 // ctl = incoming control; mem* = incoming memory
3633 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
3634 // First allocate uninitialized memory and fill in the header:
3635 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
3636 // ctl := alloc.Control; mem* := alloc.Memory*
3637 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
3638 // Then initialize to zero the non-header parts of the raw memory block:
3639 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
3640 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
3641 // After the initialize node executes, the object is ready for service:
3642 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
3643 // Suppose its body is immediately initialized as {1,2}:
3644 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3645 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3646 // mem.SLICE(#short[*]) := store2
3647 //
3648 // DETAILS:
3649 // An InitializeNode collects and isolates object initialization after
3650 // an AllocateNode and before the next possible safepoint. As a
3651 // memory barrier (MemBarNode), it keeps critical stores from drifting
3652 // down past any safepoint or any publication of the allocation.
3653 // Before this barrier, a newly-allocated object may have uninitialized bits.
3654 // After this barrier, it may be treated as a real oop, and GC is allowed.
3655 //
3656 // The semantics of the InitializeNode include an implicit zeroing of
3657 // the new object from object header to the end of the object.
3658 // (The object header and end are determined by the AllocateNode.)
3659 //
3660 // Certain stores may be added as direct inputs to the InitializeNode.
3661 // These stores must update raw memory, and they must be to addresses
3662 // derived from the raw address produced by AllocateNode, and with
3663 // a constant offset. They must be ordered by increasing offset.
3664 // The first one is at in(RawStores), the last at in(req()-1).
3665 // Unlike most memory operations, they are not linked in a chain,
3666 // but are displayed in parallel as users of the rawmem output of
3667 // the allocation.
3668 //
3669 // (See comments in InitializeNode::capture_store, which continue
3670 // the example given above.)
3671 //
3672 // When the associated Allocate is macro-expanded, the InitializeNode
3673 // may be rewritten to optimize collected stores. A ClearArrayNode
3674 // may also be created at that point to represent any required zeroing.
3675 // The InitializeNode is then marked 'complete', prohibiting further
3676 // capturing of nearby memory operations.
3677 //
3678 // During macro-expansion, all captured initializations which store
3679 // constant values of 32 bits or smaller are coalesced (if advantageous)
3680 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3681 // initialized in fewer memory operations. Memory words which are
3682 // covered by neither tiles nor non-constant stores are pre-zeroed
3683 // by explicit stores of zero. (The code shape happens to do all
3684 // zeroing first, then all other stores, with both sequences occurring
3685 // in order of ascending offsets.)
3686 //
3687 // Alternatively, code may be inserted between an AllocateNode and its
3688 // InitializeNode, to perform arbitrary initialization of the new object.
3689 // E.g., the object copying intrinsics insert complex data transfers here.
3690 // The initialization must then be marked as 'complete' disable the
3691 // built-in zeroing semantics and the collection of initializing stores.
3692 //
3693 // While an InitializeNode is incomplete, reads from the memory state
3694 // produced by it are optimizable if they match the control edge and
3695 // new oop address associated with the allocation/initialization.
3696 // They return a stored value (if the offset matches) or else zero.
3697 // A write to the memory state, if it matches control and address,
3698 // and if it is to a constant offset, may be 'captured' by the
3699 // InitializeNode. It is cloned as a raw memory operation and rewired
3700 // inside the initialization, to the raw oop produced by the allocation.
3701 // Operations on addresses which are provably distinct (e.g., to
3702 // other AllocateNodes) are allowed to bypass the initialization.
3703 //
3704 // The effect of all this is to consolidate object initialization
3705 // (both arrays and non-arrays, both piecewise and bulk) into a
3706 // single location, where it can be optimized as a unit.
3707 //
3708 // Only stores with an offset less than TrackedInitializationLimit words
3709 // will be considered for capture by an InitializeNode. This puts a
3710 // reasonable limit on the complexity of optimized initializations.
3711
3712 //---------------------------InitializeNode------------------------------------
3713 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3714 : MemBarNode(C, adr_type, rawoop),
3715 _is_complete(Incomplete), _does_not_escape(false)
3716 {
3717 init_class_id(Class_Initialize);
3718
3719 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3720 assert(in(RawAddress) == rawoop, "proper init");
3721 // Note: allocation() can be NULL, for secondary initialization barriers
3722 }
3723
3724 // Since this node is not matched, it will be processed by the
3725 // register allocator. Declare that there are no constraints
3726 // on the allocation of the RawAddress edge.
3727 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3728 // This edge should be set to top, by the set_complete. But be conservative.
3729 if (idx == InitializeNode::RawAddress)
3730 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3731 return RegMask::Empty;
3732 }
3733
3734 Node* InitializeNode::memory(uint alias_idx) {
3735 Node* mem = in(Memory);
3736 if (mem->is_MergeMem()) {
3737 return mem->as_MergeMem()->memory_at(alias_idx);
3738 } else {
3739 // incoming raw memory is not split
3740 return mem;
3741 }
3742 }
3743
3744 bool InitializeNode::is_non_zero() {
3745 if (is_complete()) return false;
3746 remove_extra_zeroes();
3747 return (req() > RawStores);
3748 }
3749
3750 void InitializeNode::set_complete(PhaseGVN* phase) {
3751 assert(!is_complete(), "caller responsibility");
3752 _is_complete = Complete;
3753
3754 // After this node is complete, it contains a bunch of
3755 // raw-memory initializations. There is no need for
3756 // it to have anything to do with non-raw memory effects.
3757 // Therefore, tell all non-raw users to re-optimize themselves,
3758 // after skipping the memory effects of this initialization.
3759 PhaseIterGVN* igvn = phase->is_IterGVN();
3760 if (igvn) igvn->add_users_to_worklist(this);
3761 }
3762
3763 // convenience function
3764 // return false if the init contains any stores already
3765 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3766 InitializeNode* init = initialization();
3767 if (init == NULL || init->is_complete()) {
3768 return false;
3769 }
3770 init->remove_extra_zeroes();
3771 // for now, if this allocation has already collected any inits, bail:
3772 if (init->is_non_zero()) return false;
3773 init->set_complete(phase);
3774 return true;
3775 }
3776
3777 void InitializeNode::remove_extra_zeroes() {
3778 if (req() == RawStores) return;
3779 Node* zmem = zero_memory();
3780 uint fill = RawStores;
3781 for (uint i = fill; i < req(); i++) {
3782 Node* n = in(i);
3783 if (n->is_top() || n == zmem) continue; // skip
3784 if (fill < i) set_req(fill, n); // compact
3785 ++fill;
3786 }
3787 // delete any empty spaces created:
3788 while (fill < req()) {
3789 del_req(fill);
3790 }
3791 }
3792
3793 // Helper for remembering which stores go with which offsets.
3794 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3795 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3796 intptr_t offset = -1;
3797 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3798 phase, offset);
3799 if (base == NULL) return -1; // something is dead,
3800 if (offset < 0) return -1; // dead, dead
3801 return offset;
3802 }
3803
3804 // Helper for proving that an initialization expression is
3805 // "simple enough" to be folded into an object initialization.
3806 // Attempts to prove that a store's initial value 'n' can be captured
3807 // within the initialization without creating a vicious cycle, such as:
3808 // { Foo p = new Foo(); p.next = p; }
3809 // True for constants and parameters and small combinations thereof.
3810 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
3811 ResourceMark rm;
3812 Unique_Node_List worklist;
3813 worklist.push(value);
3814
3815 uint complexity_limit = 20;
3816 for (uint j = 0; j < worklist.size(); j++) {
3817 if (j >= complexity_limit) {
3818 return false; // Bail out if processed too many nodes
3819 }
3820
3821 Node* n = worklist.at(j);
3822 if (n == NULL) continue; // (can this really happen?)
3823 if (n->is_Proj()) n = n->in(0);
3824 if (n == this) return false; // found a cycle
3825 if (n->is_Con()) continue;
3826 if (n->is_Start()) continue; // params, etc., are OK
3827 if (n->is_Root()) continue; // even better
3828
3829 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
3830 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
3831 continue;
3832 }
3833
3834 Node* ctl = n->in(0);
3835 if (ctl != NULL && !ctl->is_top()) {
3836 if (ctl->is_Proj()) ctl = ctl->in(0);
3837 if (ctl == this) return false;
3838
3839 // If we already know that the enclosing memory op is pinned right after
3840 // the init, then any control flow that the store has picked up
3841 // must have preceded the init, or else be equal to the init.
3842 // Even after loop optimizations (which might change control edges)
3843 // a store is never pinned *before* the availability of its inputs.
3844 if (!MemNode::all_controls_dominate(n, this))
3845 return false; // failed to prove a good control
3846 }
3847
3848 // Check data edges for possible dependencies on 'this'.
3849 for (uint i = 1; i < n->req(); i++) {
3850 Node* m = n->in(i);
3851 if (m == NULL || m == n || m->is_top()) continue;
3852
3853 // Only process data inputs once
3854 worklist.push(m);
3855 }
3856 }
3857
3858 return true;
3859 }
3860
3861 // Here are all the checks a Store must pass before it can be moved into
3862 // an initialization. Returns zero if a check fails.
3863 // On success, returns the (constant) offset to which the store applies,
3864 // within the initialized memory.
3865 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
3866 const int FAIL = 0;
3867 if (st->req() != MemNode::ValueIn + 1)
3868 return FAIL; // an inscrutable StoreNode (card mark?)
3869 Node* ctl = st->in(MemNode::Control);
3870 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3871 return FAIL; // must be unconditional after the initialization
3872 Node* mem = st->in(MemNode::Memory);
3873 if (!(mem->is_Proj() && mem->in(0) == this))
3874 return FAIL; // must not be preceded by other stores
3875 Node* adr = st->in(MemNode::Address);
3876 intptr_t offset;
3877 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3878 if (alloc == NULL)
3879 return FAIL; // inscrutable address
3880 if (alloc != allocation())
3881 return FAIL; // wrong allocation! (store needs to float up)
3882 int size_in_bytes = st->memory_size();
3883 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
3884 return FAIL; // mismatched access
3885 }
3886 Node* val = st->in(MemNode::ValueIn);
3887
3888 if (!detect_init_independence(val, phase))
3889 return FAIL; // stored value must be 'simple enough'
3890
3891 // The Store can be captured only if nothing after the allocation
3892 // and before the Store is using the memory location that the store
3893 // overwrites.
3894 bool failed = false;
3895 // If is_complete_with_arraycopy() is true the shape of the graph is
3896 // well defined and is safe so no need for extra checks.
3897 if (!is_complete_with_arraycopy()) {
3898 // We are going to look at each use of the memory state following
3899 // the allocation to make sure nothing reads the memory that the
3900 // Store writes.
3901 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3902 int alias_idx = phase->C->get_alias_index(t_adr);
3903 ResourceMark rm;
3904 Unique_Node_List mems;
3905 mems.push(mem);
3906 Node* unique_merge = NULL;
3907 for (uint next = 0; next < mems.size(); ++next) {
3908 Node *m = mems.at(next);
3909 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3910 Node *n = m->fast_out(j);
3911 if (n->outcnt() == 0) {
3912 continue;
3913 }
3914 if (n == st) {
3915 continue;
3916 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3917 // If the control of this use is different from the control
3918 // of the Store which is right after the InitializeNode then
3919 // this node cannot be between the InitializeNode and the
3920 // Store.
3921 continue;
3922 } else if (n->is_MergeMem()) {
3923 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3924 // We can hit a MergeMemNode (that will likely go away
3925 // later) that is a direct use of the memory state
3926 // following the InitializeNode on the same slice as the
3927 // store node that we'd like to capture. We need to check
3928 // the uses of the MergeMemNode.
3929 mems.push(n);
3930 }
3931 } else if (n->is_Mem()) {
3932 Node* other_adr = n->in(MemNode::Address);
3933 if (other_adr == adr) {
3934 failed = true;
3935 break;
3936 } else {
3937 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3938 if (other_t_adr != NULL) {
3939 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3940 if (other_alias_idx == alias_idx) {
3941 // A load from the same memory slice as the store right
3942 // after the InitializeNode. We check the control of the
3943 // object/array that is loaded from. If it's the same as
3944 // the store control then we cannot capture the store.
3945 assert(!n->is_Store(), "2 stores to same slice on same control?");
3946 Node* base = other_adr;
3947 if (base->is_Phi()) {
3948 // In rare case, base may be a PhiNode and it may read
3949 // the same memory slice between InitializeNode and store.
3950 failed = true;
3951 break;
3952 }
3953 assert(base->is_AddP(), "should be addp but is %s", base->Name());
3954 base = base->in(AddPNode::Base);
3955 if (base != NULL) {
3956 base = base->uncast();
3957 if (base->is_Proj() && base->in(0) == alloc) {
3958 failed = true;
3959 break;
3960 }
3961 }
3962 }
3963 }
3964 }
3965 } else {
3966 failed = true;
3967 break;
3968 }
3969 }
3970 }
3971 }
3972 if (failed) {
3973 if (!can_reshape) {
3974 // We decided we couldn't capture the store during parsing. We
3975 // should try again during the next IGVN once the graph is
3976 // cleaner.
3977 phase->C->record_for_igvn(st);
3978 }
3979 return FAIL;
3980 }
3981
3982 return offset; // success
3983 }
3984
3985 // Find the captured store in(i) which corresponds to the range
3986 // [start..start+size) in the initialized object.
3987 // If there is one, return its index i. If there isn't, return the
3988 // negative of the index where it should be inserted.
3989 // Return 0 if the queried range overlaps an initialization boundary
3990 // or if dead code is encountered.
3991 // If size_in_bytes is zero, do not bother with overlap checks.
3992 int InitializeNode::captured_store_insertion_point(intptr_t start,
3993 int size_in_bytes,
3994 PhaseTransform* phase) {
3995 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
3996
3997 if (is_complete())
3998 return FAIL; // arraycopy got here first; punt
3999
4000 assert(allocation() != NULL, "must be present");
4001
4002 // no negatives, no header fields:
4003 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
4004
4005 // after a certain size, we bail out on tracking all the stores:
4006 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4007 if (start >= ti_limit) return FAIL;
4008
4009 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
4010 if (i >= limit) return -(int)i; // not found; here is where to put it
4011
4012 Node* st = in(i);
4013 intptr_t st_off = get_store_offset(st, phase);
4014 if (st_off < 0) {
4015 if (st != zero_memory()) {
4016 return FAIL; // bail out if there is dead garbage
4017 }
4018 } else if (st_off > start) {
4019 // ...we are done, since stores are ordered
4020 if (st_off < start + size_in_bytes) {
4021 return FAIL; // the next store overlaps
4022 }
4023 return -(int)i; // not found; here is where to put it
4024 } else if (st_off < start) {
4025 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
4026 if (size_in_bytes != 0 &&
4027 start < st_off + MAX_STORE &&
4028 start < st_off + st->as_Store()->memory_size()) {
4029 return FAIL; // the previous store overlaps
4030 }
4031 } else {
4032 if (size_in_bytes != 0 &&
4033 st->as_Store()->memory_size() != size_in_bytes) {
4034 return FAIL; // mismatched store size
4035 }
4036 return i;
4037 }
4038
4039 ++i;
4040 }
4041 }
4042
4043 // Look for a captured store which initializes at the offset 'start'
4044 // with the given size. If there is no such store, and no other
4045 // initialization interferes, then return zero_memory (the memory
4046 // projection of the AllocateNode).
4047 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
4048 PhaseTransform* phase) {
4049 assert(stores_are_sane(phase), "");
4050 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4051 if (i == 0) {
4052 return NULL; // something is dead
4053 } else if (i < 0) {
4054 return zero_memory(); // just primordial zero bits here
4055 } else {
4056 Node* st = in(i); // here is the store at this position
4057 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
4058 return st;
4059 }
4060 }
4061
4062 // Create, as a raw pointer, an address within my new object at 'offset'.
4063 Node* InitializeNode::make_raw_address(intptr_t offset,
4064 PhaseTransform* phase) {
4065 Node* addr = in(RawAddress);
4066 if (offset != 0) {
4067 Compile* C = phase->C;
4068 addr = phase->transform( new AddPNode(C->top(), addr,
4069 phase->MakeConX(offset)) );
4070 }
4071 return addr;
4072 }
4073
4074 // Clone the given store, converting it into a raw store
4075 // initializing a field or element of my new object.
4076 // Caller is responsible for retiring the original store,
4077 // with subsume_node or the like.
4078 //
4079 // From the example above InitializeNode::InitializeNode,
4080 // here are the old stores to be captured:
4081 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4082 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4083 //
4084 // Here is the changed code; note the extra edges on init:
4085 // alloc = (Allocate ...)
4086 // rawoop = alloc.RawAddress
4087 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
4088 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
4089 // init = (Initialize alloc.Control alloc.Memory rawoop
4090 // rawstore1 rawstore2)
4091 //
4092 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
4093 PhaseGVN* phase, bool can_reshape) {
4094 assert(stores_are_sane(phase), "");
4095
4096 if (start < 0) return NULL;
4097 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
4098
4099 Compile* C = phase->C;
4100 int size_in_bytes = st->memory_size();
4101 int i = captured_store_insertion_point(start, size_in_bytes, phase);
4102 if (i == 0) return NULL; // bail out
4103 Node* prev_mem = NULL; // raw memory for the captured store
4104 if (i > 0) {
4105 prev_mem = in(i); // there is a pre-existing store under this one
4106 set_req(i, C->top()); // temporarily disconnect it
4107 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
4108 } else {
4109 i = -i; // no pre-existing store
4110 prev_mem = zero_memory(); // a slice of the newly allocated object
4111 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
4112 set_req(--i, C->top()); // reuse this edge; it has been folded away
4113 else
4114 ins_req(i, C->top()); // build a new edge
4115 }
4116 Node* new_st = st->clone();
4117 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4118 new_st->set_req(MemNode::Control, in(Control));
4119 new_st->set_req(MemNode::Memory, prev_mem);
4120 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
4121 bs->eliminate_gc_barrier_data(new_st);
4122 new_st = phase->transform(new_st);
4123
4124 // At this point, new_st might have swallowed a pre-existing store
4125 // at the same offset, or perhaps new_st might have disappeared,
4126 // if it redundantly stored the same value (or zero to fresh memory).
4127
4128 // In any case, wire it in:
4129 PhaseIterGVN* igvn = phase->is_IterGVN();
4130 if (igvn) {
4131 igvn->rehash_node_delayed(this);
4132 }
4133 set_req(i, new_st);
4134
4135 // The caller may now kill the old guy.
4136 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
4137 assert(check_st == new_st || check_st == NULL, "must be findable");
4138 assert(!is_complete(), "");
4139 return new_st;
4140 }
4141
4142 static bool store_constant(jlong* tiles, int num_tiles,
4143 intptr_t st_off, int st_size,
4144 jlong con) {
4145 if ((st_off & (st_size-1)) != 0)
4146 return false; // strange store offset (assume size==2**N)
4147 address addr = (address)tiles + st_off;
4148 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
4149 switch (st_size) {
4150 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
4151 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
4152 case sizeof(jint): *(jint*) addr = (jint) con; break;
4153 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
4154 default: return false; // strange store size (detect size!=2**N here)
4155 }
4156 return true; // return success to caller
4157 }
4158
4159 // Coalesce subword constants into int constants and possibly
4160 // into long constants. The goal, if the CPU permits,
4161 // is to initialize the object with a small number of 64-bit tiles.
4162 // Also, convert floating-point constants to bit patterns.
4163 // Non-constants are not relevant to this pass.
4164 //
4165 // In terms of the running example on InitializeNode::InitializeNode
4166 // and InitializeNode::capture_store, here is the transformation
4167 // of rawstore1 and rawstore2 into rawstore12:
4168 // alloc = (Allocate ...)
4169 // rawoop = alloc.RawAddress
4170 // tile12 = 0x00010002
4171 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
4172 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
4173 //
4174 void
4175 InitializeNode::coalesce_subword_stores(intptr_t header_size,
4176 Node* size_in_bytes,
4177 PhaseGVN* phase) {
4178 Compile* C = phase->C;
4179
4180 assert(stores_are_sane(phase), "");
4181 // Note: After this pass, they are not completely sane,
4182 // since there may be some overlaps.
4183
4184 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
4185
4186 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
4187 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
4188 size_limit = MIN2(size_limit, ti_limit);
4189 size_limit = align_up(size_limit, BytesPerLong);
4190 int num_tiles = size_limit / BytesPerLong;
4191
4192 // allocate space for the tile map:
4193 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
4194 jlong tiles_buf[small_len];
4195 Node* nodes_buf[small_len];
4196 jlong inits_buf[small_len];
4197 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
4198 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4199 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
4200 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
4201 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
4202 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
4203 // tiles: exact bitwise model of all primitive constants
4204 // nodes: last constant-storing node subsumed into the tiles model
4205 // inits: which bytes (in each tile) are touched by any initializations
4206
4207 //// Pass A: Fill in the tile model with any relevant stores.
4208
4209 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
4210 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
4211 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
4212 Node* zmem = zero_memory(); // initially zero memory state
4213 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4214 Node* st = in(i);
4215 intptr_t st_off = get_store_offset(st, phase);
4216
4217 // Figure out the store's offset and constant value:
4218 if (st_off < header_size) continue; //skip (ignore header)
4219 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
4220 int st_size = st->as_Store()->memory_size();
4221 if (st_off + st_size > size_limit) break;
4222
4223 // Record which bytes are touched, whether by constant or not.
4224 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
4225 continue; // skip (strange store size)
4226
4227 const Type* val = phase->type(st->in(MemNode::ValueIn));
4228 if (!val->singleton()) continue; //skip (non-con store)
4229 BasicType type = val->basic_type();
4230
4231 jlong con = 0;
4232 switch (type) {
4233 case T_INT: con = val->is_int()->get_con(); break;
4234 case T_LONG: con = val->is_long()->get_con(); break;
4235 case T_FLOAT: con = jint_cast(val->getf()); break;
4236 case T_DOUBLE: con = jlong_cast(val->getd()); break;
4237 default: continue; //skip (odd store type)
4238 }
4239
4240 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
4241 st->Opcode() == Op_StoreL) {
4242 continue; // This StoreL is already optimal.
4243 }
4244
4245 // Store down the constant.
4246 store_constant(tiles, num_tiles, st_off, st_size, con);
4247
4248 intptr_t j = st_off >> LogBytesPerLong;
4249
4250 if (type == T_INT && st_size == BytesPerInt
4251 && (st_off & BytesPerInt) == BytesPerInt) {
4252 jlong lcon = tiles[j];
4253 if (!Matcher::isSimpleConstant64(lcon) &&
4254 st->Opcode() == Op_StoreI) {
4255 // This StoreI is already optimal by itself.
4256 jint* intcon = (jint*) &tiles[j];
4257 intcon[1] = 0; // undo the store_constant()
4258
4259 // If the previous store is also optimal by itself, back up and
4260 // undo the action of the previous loop iteration... if we can.
4261 // But if we can't, just let the previous half take care of itself.
4262 st = nodes[j];
4263 st_off -= BytesPerInt;
4264 con = intcon[0];
4265 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
4266 assert(st_off >= header_size, "still ignoring header");
4267 assert(get_store_offset(st, phase) == st_off, "must be");
4268 assert(in(i-1) == zmem, "must be");
4269 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
4270 assert(con == tcon->is_int()->get_con(), "must be");
4271 // Undo the effects of the previous loop trip, which swallowed st:
4272 intcon[0] = 0; // undo store_constant()
4273 set_req(i-1, st); // undo set_req(i, zmem)
4274 nodes[j] = NULL; // undo nodes[j] = st
4275 --old_subword; // undo ++old_subword
4276 }
4277 continue; // This StoreI is already optimal.
4278 }
4279 }
4280
4281 // This store is not needed.
4282 set_req(i, zmem);
4283 nodes[j] = st; // record for the moment
4284 if (st_size < BytesPerLong) // something has changed
4285 ++old_subword; // includes int/float, but who's counting...
4286 else ++old_long;
4287 }
4288
4289 if ((old_subword + old_long) == 0)
4290 return; // nothing more to do
4291
4292 //// Pass B: Convert any non-zero tiles into optimal constant stores.
4293 // Be sure to insert them before overlapping non-constant stores.
4294 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
4295 for (int j = 0; j < num_tiles; j++) {
4296 jlong con = tiles[j];
4297 jlong init = inits[j];
4298 if (con == 0) continue;
4299 jint con0, con1; // split the constant, address-wise
4300 jint init0, init1; // split the init map, address-wise
4301 { union { jlong con; jint intcon[2]; } u;
4302 u.con = con;
4303 con0 = u.intcon[0];
4304 con1 = u.intcon[1];
4305 u.con = init;
4306 init0 = u.intcon[0];
4307 init1 = u.intcon[1];
4308 }
4309
4310 Node* old = nodes[j];
4311 assert(old != NULL, "need the prior store");
4312 intptr_t offset = (j * BytesPerLong);
4313
4314 bool split = !Matcher::isSimpleConstant64(con);
4315
4316 if (offset < header_size) {
4317 assert(offset + BytesPerInt >= header_size, "second int counts");
4318 assert(*(jint*)&tiles[j] == 0, "junk in header");
4319 split = true; // only the second word counts
4320 // Example: int a[] = { 42 ... }
4321 } else if (con0 == 0 && init0 == -1) {
4322 split = true; // first word is covered by full inits
4323 // Example: int a[] = { ... foo(), 42 ... }
4324 } else if (con1 == 0 && init1 == -1) {
4325 split = true; // second word is covered by full inits
4326 // Example: int a[] = { ... 42, foo() ... }
4327 }
4328
4329 // Here's a case where init0 is neither 0 nor -1:
4330 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
4331 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
4332 // In this case the tile is not split; it is (jlong)42.
4333 // The big tile is stored down, and then the foo() value is inserted.
4334 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
4335
4336 Node* ctl = old->in(MemNode::Control);
4337 Node* adr = make_raw_address(offset, phase);
4338 const TypePtr* atp = TypeRawPtr::BOTTOM;
4339
4340 // One or two coalesced stores to plop down.
4341 Node* st[2];
4342 intptr_t off[2];
4343 int nst = 0;
4344 if (!split) {
4345 ++new_long;
4346 off[nst] = offset;
4347 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4348 phase->longcon(con), T_LONG, MemNode::unordered);
4349 } else {
4350 // Omit either if it is a zero.
4351 if (con0 != 0) {
4352 ++new_int;
4353 off[nst] = offset;
4354 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4355 phase->intcon(con0), T_INT, MemNode::unordered);
4356 }
4357 if (con1 != 0) {
4358 ++new_int;
4359 offset += BytesPerInt;
4360 adr = make_raw_address(offset, phase);
4361 off[nst] = offset;
4362 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
4363 phase->intcon(con1), T_INT, MemNode::unordered);
4364 }
4365 }
4366
4367 // Insert second store first, then the first before the second.
4368 // Insert each one just before any overlapping non-constant stores.
4369 while (nst > 0) {
4370 Node* st1 = st[--nst];
4371 C->copy_node_notes_to(st1, old);
4372 st1 = phase->transform(st1);
4373 offset = off[nst];
4374 assert(offset >= header_size, "do not smash header");
4375 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
4376 guarantee(ins_idx != 0, "must re-insert constant store");
4377 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
4378 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
4379 set_req(--ins_idx, st1);
4380 else
4381 ins_req(ins_idx, st1);
4382 }
4383 }
4384
4385 if (PrintCompilation && WizardMode)
4386 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
4387 old_subword, old_long, new_int, new_long);
4388 if (C->log() != NULL)
4389 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
4390 old_subword, old_long, new_int, new_long);
4391
4392 // Clean up any remaining occurrences of zmem:
4393 remove_extra_zeroes();
4394 }
4395
4396 // Explore forward from in(start) to find the first fully initialized
4397 // word, and return its offset. Skip groups of subword stores which
4398 // together initialize full words. If in(start) is itself part of a
4399 // fully initialized word, return the offset of in(start). If there
4400 // are no following full-word stores, or if something is fishy, return
4401 // a negative value.
4402 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
4403 int int_map = 0;
4404 intptr_t int_map_off = 0;
4405 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
4406
4407 for (uint i = start, limit = req(); i < limit; i++) {
4408 Node* st = in(i);
4409
4410 intptr_t st_off = get_store_offset(st, phase);
4411 if (st_off < 0) break; // return conservative answer
4412
4413 int st_size = st->as_Store()->memory_size();
4414 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
4415 return st_off; // we found a complete word init
4416 }
4417
4418 // update the map:
4419
4420 intptr_t this_int_off = align_down(st_off, BytesPerInt);
4421 if (this_int_off != int_map_off) {
4422 // reset the map:
4423 int_map = 0;
4424 int_map_off = this_int_off;
4425 }
4426
4427 int subword_off = st_off - this_int_off;
4428 int_map |= right_n_bits(st_size) << subword_off;
4429 if ((int_map & FULL_MAP) == FULL_MAP) {
4430 return this_int_off; // we found a complete word init
4431 }
4432
4433 // Did this store hit or cross the word boundary?
4434 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
4435 if (next_int_off == this_int_off + BytesPerInt) {
4436 // We passed the current int, without fully initializing it.
4437 int_map_off = next_int_off;
4438 int_map >>= BytesPerInt;
4439 } else if (next_int_off > this_int_off + BytesPerInt) {
4440 // We passed the current and next int.
4441 return this_int_off + BytesPerInt;
4442 }
4443 }
4444
4445 return -1;
4446 }
4447
4448
4449 // Called when the associated AllocateNode is expanded into CFG.
4450 // At this point, we may perform additional optimizations.
4451 // Linearize the stores by ascending offset, to make memory
4452 // activity as coherent as possible.
4453 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
4454 intptr_t header_size,
4455 Node* size_in_bytes,
4456 PhaseIterGVN* phase) {
4457 assert(!is_complete(), "not already complete");
4458 assert(stores_are_sane(phase), "");
4459 assert(allocation() != NULL, "must be present");
4460
4461 remove_extra_zeroes();
4462
4463 if (ReduceFieldZeroing || ReduceBulkZeroing)
4464 // reduce instruction count for common initialization patterns
4465 coalesce_subword_stores(header_size, size_in_bytes, phase);
4466
4467 Node* zmem = zero_memory(); // initially zero memory state
4468 Node* inits = zmem; // accumulating a linearized chain of inits
4469 #ifdef ASSERT
4470 intptr_t first_offset = allocation()->minimum_header_size();
4471 intptr_t last_init_off = first_offset; // previous init offset
4472 intptr_t last_init_end = first_offset; // previous init offset+size
4473 intptr_t last_tile_end = first_offset; // previous tile offset+size
4474 #endif
4475 intptr_t zeroes_done = header_size;
4476
4477 bool do_zeroing = true; // we might give up if inits are very sparse
4478 int big_init_gaps = 0; // how many large gaps have we seen?
4479
4480 if (UseTLAB && ZeroTLAB) do_zeroing = false;
4481 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
4482
4483 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
4484 Node* st = in(i);
4485 intptr_t st_off = get_store_offset(st, phase);
4486 if (st_off < 0)
4487 break; // unknown junk in the inits
4488 if (st->in(MemNode::Memory) != zmem)
4489 break; // complicated store chains somehow in list
4490
4491 int st_size = st->as_Store()->memory_size();
4492 intptr_t next_init_off = st_off + st_size;
4493
4494 if (do_zeroing && zeroes_done < next_init_off) {
4495 // See if this store needs a zero before it or under it.
4496 intptr_t zeroes_needed = st_off;
4497
4498 if (st_size < BytesPerInt) {
4499 // Look for subword stores which only partially initialize words.
4500 // If we find some, we must lay down some word-level zeroes first,
4501 // underneath the subword stores.
4502 //
4503 // Examples:
4504 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
4505 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
4506 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
4507 //
4508 // Note: coalesce_subword_stores may have already done this,
4509 // if it was prompted by constant non-zero subword initializers.
4510 // But this case can still arise with non-constant stores.
4511
4512 intptr_t next_full_store = find_next_fullword_store(i, phase);
4513
4514 // In the examples above:
4515 // in(i) p q r s x y z
4516 // st_off 12 13 14 15 12 13 14
4517 // st_size 1 1 1 1 1 1 1
4518 // next_full_s. 12 16 16 16 16 16 16
4519 // z's_done 12 16 16 16 12 16 12
4520 // z's_needed 12 16 16 16 16 16 16
4521 // zsize 0 0 0 0 4 0 4
4522 if (next_full_store < 0) {
4523 // Conservative tack: Zero to end of current word.
4524 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
4525 } else {
4526 // Zero to beginning of next fully initialized word.
4527 // Or, don't zero at all, if we are already in that word.
4528 assert(next_full_store >= zeroes_needed, "must go forward");
4529 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
4530 zeroes_needed = next_full_store;
4531 }
4532 }
4533
4534 if (zeroes_needed > zeroes_done) {
4535 intptr_t zsize = zeroes_needed - zeroes_done;
4536 // Do some incremental zeroing on rawmem, in parallel with inits.
4537 zeroes_done = align_down(zeroes_done, BytesPerInt);
4538 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4539 allocation()->in(AllocateNode::DefaultValue),
4540 allocation()->in(AllocateNode::RawDefaultValue),
4541 zeroes_done, zeroes_needed,
4542 phase);
4543 zeroes_done = zeroes_needed;
4544 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
4545 do_zeroing = false; // leave the hole, next time
4546 }
4547 }
4548
4549 // Collect the store and move on:
4550 phase->replace_input_of(st, MemNode::Memory, inits);
4551 inits = st; // put it on the linearized chain
4552 set_req(i, zmem); // unhook from previous position
4553
4554 if (zeroes_done == st_off)
4555 zeroes_done = next_init_off;
4556
4557 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
4558
4559 #ifdef ASSERT
4560 // Various order invariants. Weaker than stores_are_sane because
4561 // a large constant tile can be filled in by smaller non-constant stores.
4562 assert(st_off >= last_init_off, "inits do not reverse");
4563 last_init_off = st_off;
4564 const Type* val = NULL;
4565 if (st_size >= BytesPerInt &&
4566 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
4567 (int)val->basic_type() < (int)T_OBJECT) {
4568 assert(st_off >= last_tile_end, "tiles do not overlap");
4569 assert(st_off >= last_init_end, "tiles do not overwrite inits");
4570 last_tile_end = MAX2(last_tile_end, next_init_off);
4571 } else {
4572 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
4573 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
4574 assert(st_off >= last_init_end, "inits do not overlap");
4575 last_init_end = next_init_off; // it's a non-tile
4576 }
4577 #endif //ASSERT
4578 }
4579
4580 remove_extra_zeroes(); // clear out all the zmems left over
4581 add_req(inits);
4582
4583 if (!(UseTLAB && ZeroTLAB)) {
4584 // If anything remains to be zeroed, zero it all now.
4585 zeroes_done = align_down(zeroes_done, BytesPerInt);
4586 // if it is the last unused 4 bytes of an instance, forget about it
4587 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
4588 if (zeroes_done + BytesPerLong >= size_limit) {
4589 AllocateNode* alloc = allocation();
4590 assert(alloc != NULL, "must be present");
4591 if (alloc != NULL && alloc->Opcode() == Op_Allocate) {
4592 Node* klass_node = alloc->in(AllocateNode::KlassNode);
4593 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
4594 if (zeroes_done == k->layout_helper())
4595 zeroes_done = size_limit;
4596 }
4597 }
4598 if (zeroes_done < size_limit) {
4599 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
4600 allocation()->in(AllocateNode::DefaultValue),
4601 allocation()->in(AllocateNode::RawDefaultValue),
4602 zeroes_done, size_in_bytes, phase);
4603 }
4604 }
4605
4606 set_complete(phase);
4607 return rawmem;
4608 }
4609
4610
4611 #ifdef ASSERT
4612 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
4613 if (is_complete())
4614 return true; // stores could be anything at this point
4615 assert(allocation() != NULL, "must be present");
4616 intptr_t last_off = allocation()->minimum_header_size();
4617 for (uint i = InitializeNode::RawStores; i < req(); i++) {
4618 Node* st = in(i);
4619 intptr_t st_off = get_store_offset(st, phase);
4620 if (st_off < 0) continue; // ignore dead garbage
4621 if (last_off > st_off) {
4622 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
4623 this->dump(2);
4624 assert(false, "ascending store offsets");
4625 return false;
4626 }
4627 last_off = st_off + st->as_Store()->memory_size();
4628 }
4629 return true;
4630 }
4631 #endif //ASSERT
4632
4633
4634
4635
4636 //============================MergeMemNode=====================================
4637 //
4638 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
4639 // contributing store or call operations. Each contributor provides the memory
4640 // state for a particular "alias type" (see Compile::alias_type). For example,
4641 // if a MergeMem has an input X for alias category #6, then any memory reference
4642 // to alias category #6 may use X as its memory state input, as an exact equivalent
4643 // to using the MergeMem as a whole.
4644 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
4645 //
4646 // (Here, the <N> notation gives the index of the relevant adr_type.)
4647 //
4648 // In one special case (and more cases in the future), alias categories overlap.
4649 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
4650 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
4651 // it is exactly equivalent to that state W:
4652 // MergeMem(<Bot>: W) <==> W
4653 //
4654 // Usually, the merge has more than one input. In that case, where inputs
4655 // overlap (i.e., one is Bot), the narrower alias type determines the memory
4656 // state for that type, and the wider alias type (Bot) fills in everywhere else:
4657 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
4658 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
4659 //
4660 // A merge can take a "wide" memory state as one of its narrow inputs.
4661 // This simply means that the merge observes out only the relevant parts of
4662 // the wide input. That is, wide memory states arriving at narrow merge inputs
4663 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
4664 //
4665 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
4666 // and that memory slices "leak through":
4667 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
4668 //
4669 // But, in such a cascade, repeated memory slices can "block the leak":
4670 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
4671 //
4672 // In the last example, Y is not part of the combined memory state of the
4673 // outermost MergeMem. The system must, of course, prevent unschedulable
4674 // memory states from arising, so you can be sure that the state Y is somehow
4675 // a precursor to state Y'.
4676 //
4677 //
4678 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
4679 // of each MergeMemNode array are exactly the numerical alias indexes, including
4680 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4681 // Compile::alias_type (and kin) produce and manage these indexes.
4682 //
4683 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4684 // (Note that this provides quick access to the top node inside MergeMem methods,
4685 // without the need to reach out via TLS to Compile::current.)
4686 //
4687 // As a consequence of what was just described, a MergeMem that represents a full
4688 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4689 // containing all alias categories.
4690 //
4691 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4692 //
4693 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4694 // a memory state for the alias type <N>, or else the top node, meaning that
4695 // there is no particular input for that alias type. Note that the length of
4696 // a MergeMem is variable, and may be extended at any time to accommodate new
4697 // memory states at larger alias indexes. When merges grow, they are of course
4698 // filled with "top" in the unused in() positions.
4699 //
4700 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4701 // (Top was chosen because it works smoothly with passes like GCM.)
4702 //
4703 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4704 // the type of random VM bits like TLS references.) Since it is always the
4705 // first non-Bot memory slice, some low-level loops use it to initialize an
4706 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4707 //
4708 //
4709 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4710 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4711 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4712 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4713 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4714 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4715 //
4716 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4717 // really that different from the other memory inputs. An abbreviation called
4718 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4719 //
4720 //
4721 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4722 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4723 // that "emerges though" the base memory will be marked as excluding the alias types
4724 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4725 //
4726 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4727 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4728 //
4729 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4730 // (It is currently unimplemented.) As you can see, the resulting merge is
4731 // actually a disjoint union of memory states, rather than an overlay.
4732 //
4733
4734 //------------------------------MergeMemNode-----------------------------------
4735 Node* MergeMemNode::make_empty_memory() {
4736 Node* empty_memory = (Node*) Compile::current()->top();
4737 assert(empty_memory->is_top(), "correct sentinel identity");
4738 return empty_memory;
4739 }
4740
4741 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4742 init_class_id(Class_MergeMem);
4743 // all inputs are nullified in Node::Node(int)
4744 // set_input(0, NULL); // no control input
4745
4746 // Initialize the edges uniformly to top, for starters.
4747 Node* empty_mem = make_empty_memory();
4748 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4749 init_req(i,empty_mem);
4750 }
4751 assert(empty_memory() == empty_mem, "");
4752
4753 if( new_base != NULL && new_base->is_MergeMem() ) {
4754 MergeMemNode* mdef = new_base->as_MergeMem();
4755 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4756 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4757 mms.set_memory(mms.memory2());
4758 }
4759 assert(base_memory() == mdef->base_memory(), "");
4760 } else {
4761 set_base_memory(new_base);
4762 }
4763 }
4764
4765 // Make a new, untransformed MergeMem with the same base as 'mem'.
4766 // If mem is itself a MergeMem, populate the result with the same edges.
4767 MergeMemNode* MergeMemNode::make(Node* mem) {
4768 return new MergeMemNode(mem);
4769 }
4770
4771 //------------------------------cmp--------------------------------------------
4772 uint MergeMemNode::hash() const { return NO_HASH; }
4773 bool MergeMemNode::cmp( const Node &n ) const {
4774 return (&n == this); // Always fail except on self
4775 }
4776
4777 //------------------------------Identity---------------------------------------
4778 Node* MergeMemNode::Identity(PhaseGVN* phase) {
4779 // Identity if this merge point does not record any interesting memory
4780 // disambiguations.
4781 Node* base_mem = base_memory();
4782 Node* empty_mem = empty_memory();
4783 if (base_mem != empty_mem) { // Memory path is not dead?
4784 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4785 Node* mem = in(i);
4786 if (mem != empty_mem && mem != base_mem) {
4787 return this; // Many memory splits; no change
4788 }
4789 }
4790 }
4791 return base_mem; // No memory splits; ID on the one true input
4792 }
4793
4794 //------------------------------Ideal------------------------------------------
4795 // This method is invoked recursively on chains of MergeMem nodes
4796 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4797 // Remove chain'd MergeMems
4798 //
4799 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4800 // relative to the "in(Bot)". Since we are patching both at the same time,
4801 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4802 // but rewrite each "in(i)" relative to the new "in(Bot)".
4803 Node *progress = NULL;
4804
4805
4806 Node* old_base = base_memory();
4807 Node* empty_mem = empty_memory();
4808 if (old_base == empty_mem)
4809 return NULL; // Dead memory path.
4810
4811 MergeMemNode* old_mbase;
4812 if (old_base != NULL && old_base->is_MergeMem())
4813 old_mbase = old_base->as_MergeMem();
4814 else
4815 old_mbase = NULL;
4816 Node* new_base = old_base;
4817
4818 // simplify stacked MergeMems in base memory
4819 if (old_mbase) new_base = old_mbase->base_memory();
4820
4821 // the base memory might contribute new slices beyond my req()
4822 if (old_mbase) grow_to_match(old_mbase);
4823
4824 // Note: We do not call verify_sparse on entry, because inputs
4825 // can normalize to the base_memory via subsume_node or similar
4826 // mechanisms. This method repairs that damage.
4827
4828 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4829
4830 // Look at each slice.
4831 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4832 Node* old_in = in(i);
4833 // calculate the old memory value
4834 Node* old_mem = old_in;
4835 if (old_mem == empty_mem) old_mem = old_base;
4836 assert(old_mem == memory_at(i), "");
4837
4838 // maybe update (reslice) the old memory value
4839
4840 // simplify stacked MergeMems
4841 Node* new_mem = old_mem;
4842 MergeMemNode* old_mmem;
4843 if (old_mem != NULL && old_mem->is_MergeMem())
4844 old_mmem = old_mem->as_MergeMem();
4845 else
4846 old_mmem = NULL;
4847 if (old_mmem == this) {
4848 // This can happen if loops break up and safepoints disappear.
4849 // A merge of BotPtr (default) with a RawPtr memory derived from a
4850 // safepoint can be rewritten to a merge of the same BotPtr with
4851 // the BotPtr phi coming into the loop. If that phi disappears
4852 // also, we can end up with a self-loop of the mergemem.
4853 // In general, if loops degenerate and memory effects disappear,
4854 // a mergemem can be left looking at itself. This simply means
4855 // that the mergemem's default should be used, since there is
4856 // no longer any apparent effect on this slice.
4857 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4858 // from start. Update the input to TOP.
4859 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4860 }
4861 else if (old_mmem != NULL) {
4862 new_mem = old_mmem->memory_at(i);
4863 }
4864 // else preceding memory was not a MergeMem
4865
4866 // maybe store down a new value
4867 Node* new_in = new_mem;
4868 if (new_in == new_base) new_in = empty_mem;
4869
4870 if (new_in != old_in) {
4871 // Warning: Do not combine this "if" with the previous "if"
4872 // A memory slice might have be be rewritten even if it is semantically
4873 // unchanged, if the base_memory value has changed.
4874 set_req_X(i, new_in, phase);
4875 progress = this; // Report progress
4876 }
4877 }
4878
4879 if (new_base != old_base) {
4880 set_req_X(Compile::AliasIdxBot, new_base, phase);
4881 // Don't use set_base_memory(new_base), because we need to update du.
4882 assert(base_memory() == new_base, "");
4883 progress = this;
4884 }
4885
4886 if( base_memory() == this ) {
4887 // a self cycle indicates this memory path is dead
4888 set_req(Compile::AliasIdxBot, empty_mem);
4889 }
4890
4891 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4892 // Recursion must occur after the self cycle check above
4893 if( base_memory()->is_MergeMem() ) {
4894 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4895 Node *m = phase->transform(new_mbase); // Rollup any cycles
4896 if( m != NULL &&
4897 (m->is_top() ||
4898 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
4899 // propagate rollup of dead cycle to self
4900 set_req(Compile::AliasIdxBot, empty_mem);
4901 }
4902 }
4903
4904 if( base_memory() == empty_mem ) {
4905 progress = this;
4906 // Cut inputs during Parse phase only.
4907 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4908 if( !can_reshape ) {
4909 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4910 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4911 }
4912 }
4913 }
4914
4915 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4916 // Check if PhiNode::Ideal's "Split phis through memory merges"
4917 // transform should be attempted. Look for this->phi->this cycle.
4918 uint merge_width = req();
4919 if (merge_width > Compile::AliasIdxRaw) {
4920 PhiNode* phi = base_memory()->as_Phi();
4921 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4922 if (phi->in(i) == this) {
4923 phase->is_IterGVN()->_worklist.push(phi);
4924 break;
4925 }
4926 }
4927 }
4928 }
4929
4930 assert(progress || verify_sparse(), "please, no dups of base");
4931 return progress;
4932 }
4933
4934 //-------------------------set_base_memory-------------------------------------
4935 void MergeMemNode::set_base_memory(Node *new_base) {
4936 Node* empty_mem = empty_memory();
4937 set_req(Compile::AliasIdxBot, new_base);
4938 assert(memory_at(req()) == new_base, "must set default memory");
4939 // Clear out other occurrences of new_base:
4940 if (new_base != empty_mem) {
4941 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4942 if (in(i) == new_base) set_req(i, empty_mem);
4943 }
4944 }
4945 }
4946
4947 //------------------------------out_RegMask------------------------------------
4948 const RegMask &MergeMemNode::out_RegMask() const {
4949 return RegMask::Empty;
4950 }
4951
4952 //------------------------------dump_spec--------------------------------------
4953 #ifndef PRODUCT
4954 void MergeMemNode::dump_spec(outputStream *st) const {
4955 st->print(" {");
4956 Node* base_mem = base_memory();
4957 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4958 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4959 if (mem == base_mem) { st->print(" -"); continue; }
4960 st->print( " N%d:", mem->_idx );
4961 Compile::current()->get_adr_type(i)->dump_on(st);
4962 }
4963 st->print(" }");
4964 }
4965 #endif // !PRODUCT
4966
4967
4968 #ifdef ASSERT
4969 static bool might_be_same(Node* a, Node* b) {
4970 if (a == b) return true;
4971 if (!(a->is_Phi() || b->is_Phi())) return false;
4972 // phis shift around during optimization
4973 return true; // pretty stupid...
4974 }
4975
4976 // verify a narrow slice (either incoming or outgoing)
4977 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4978 if (!VerifyAliases) return; // don't bother to verify unless requested
4979 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
4980 if (Node::in_dump()) return; // muzzle asserts when printing
4981 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4982 assert(n != NULL, "");
4983 // Elide intervening MergeMem's
4984 while (n->is_MergeMem()) {
4985 n = n->as_MergeMem()->memory_at(alias_idx);
4986 }
4987 Compile* C = Compile::current();
4988 const TypePtr* n_adr_type = n->adr_type();
4989 if (n == m->empty_memory()) {
4990 // Implicit copy of base_memory()
4991 } else if (n_adr_type != TypePtr::BOTTOM) {
4992 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4993 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4994 } else {
4995 // A few places like make_runtime_call "know" that VM calls are narrow,
4996 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4997 bool expected_wide_mem = false;
4998 if (n == m->base_memory()) {
4999 expected_wide_mem = true;
5000 } else if (alias_idx == Compile::AliasIdxRaw ||
5001 n == m->memory_at(Compile::AliasIdxRaw)) {
5002 expected_wide_mem = true;
5003 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
5004 // memory can "leak through" calls on channels that
5005 // are write-once. Allow this also.
5006 expected_wide_mem = true;
5007 }
5008 assert(expected_wide_mem, "expected narrow slice replacement");
5009 }
5010 }
5011 #else // !ASSERT
5012 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
5013 #endif
5014
5015
5016 //-----------------------------memory_at---------------------------------------
5017 Node* MergeMemNode::memory_at(uint alias_idx) const {
5018 assert(alias_idx >= Compile::AliasIdxRaw ||
5019 alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing(),
5020 "must avoid base_memory and AliasIdxTop");
5021
5022 // Otherwise, it is a narrow slice.
5023 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
5024 if (is_empty_memory(n)) {
5025 // the array is sparse; empty slots are the "top" node
5026 n = base_memory();
5027 assert(Node::in_dump()
5028 || n == NULL || n->bottom_type() == Type::TOP
5029 || n->adr_type() == NULL // address is TOP
5030 || n->adr_type() == TypePtr::BOTTOM
5031 || n->adr_type() == TypeRawPtr::BOTTOM
5032 || !Compile::current()->do_aliasing(),
5033 "must be a wide memory");
5034 // do_aliasing == false if we are organizing the memory states manually.
5035 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
5036 } else {
5037 // make sure the stored slice is sane
5038 #ifdef ASSERT
5039 if (VMError::is_error_reported() || Node::in_dump()) {
5040 } else if (might_be_same(n, base_memory())) {
5041 // Give it a pass: It is a mostly harmless repetition of the base.
5042 // This can arise normally from node subsumption during optimization.
5043 } else {
5044 verify_memory_slice(this, alias_idx, n);
5045 }
5046 #endif
5047 }
5048 return n;
5049 }
5050
5051 //---------------------------set_memory_at-------------------------------------
5052 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
5053 verify_memory_slice(this, alias_idx, n);
5054 Node* empty_mem = empty_memory();
5055 if (n == base_memory()) n = empty_mem; // collapse default
5056 uint need_req = alias_idx+1;
5057 if (req() < need_req) {
5058 if (n == empty_mem) return; // already the default, so do not grow me
5059 // grow the sparse array
5060 do {
5061 add_req(empty_mem);
5062 } while (req() < need_req);
5063 }
5064 set_req( alias_idx, n );
5065 }
5066
5067
5068
5069 //--------------------------iteration_setup------------------------------------
5070 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
5071 if (other != NULL) {
5072 grow_to_match(other);
5073 // invariant: the finite support of mm2 is within mm->req()
5074 #ifdef ASSERT
5075 for (uint i = req(); i < other->req(); i++) {
5076 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
5077 }
5078 #endif
5079 }
5080 // Replace spurious copies of base_memory by top.
5081 Node* base_mem = base_memory();
5082 if (base_mem != NULL && !base_mem->is_top()) {
5083 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
5084 if (in(i) == base_mem)
5085 set_req(i, empty_memory());
5086 }
5087 }
5088 }
5089
5090 //---------------------------grow_to_match-------------------------------------
5091 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
5092 Node* empty_mem = empty_memory();
5093 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
5094 // look for the finite support of the other memory
5095 for (uint i = other->req(); --i >= req(); ) {
5096 if (other->in(i) != empty_mem) {
5097 uint new_len = i+1;
5098 while (req() < new_len) add_req(empty_mem);
5099 break;
5100 }
5101 }
5102 }
5103
5104 //---------------------------verify_sparse-------------------------------------
5105 #ifndef PRODUCT
5106 bool MergeMemNode::verify_sparse() const {
5107 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
5108 Node* base_mem = base_memory();
5109 // The following can happen in degenerate cases, since empty==top.
5110 if (is_empty_memory(base_mem)) return true;
5111 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5112 assert(in(i) != NULL, "sane slice");
5113 if (in(i) == base_mem) return false; // should have been the sentinel value!
5114 }
5115 return true;
5116 }
5117
5118 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
5119 Node* n;
5120 n = mm->in(idx);
5121 if (mem == n) return true; // might be empty_memory()
5122 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
5123 if (mem == n) return true;
5124 return false;
5125 }
5126 #endif // !PRODUCT