1 /*
2 * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "oops/objArrayKlass.hpp"
30 #include "opto/addnode.hpp"
31 #include "opto/arraycopynode.hpp"
32 #include "opto/cfgnode.hpp"
33 #include "opto/compile.hpp"
34 #include "opto/connode.hpp"
35 #include "opto/convertnode.hpp"
36 #include "opto/loopnode.hpp"
37 #include "opto/machnode.hpp"
38 #include "opto/matcher.hpp"
39 #include "opto/memnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/narrowptrnode.hpp"
42 #include "opto/phaseX.hpp"
43 #include "opto/regmask.hpp"
44 #include "utilities/copy.hpp"
45
46 // Portions of code courtesy of Clifford Click
47
48 // Optimization - Graph Style
49
50 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
51
52 //=============================================================================
53 uint MemNode::size_of() const { return sizeof(*this); }
54
55 const TypePtr *MemNode::adr_type() const {
56 Node* adr = in(Address);
57 if (adr == NULL) return NULL; // node is dead
58 const TypePtr* cross_check = NULL;
59 DEBUG_ONLY(cross_check = _adr_type);
60 return calculate_adr_type(adr->bottom_type(), cross_check);
61 }
62
63 #ifndef PRODUCT
64 void MemNode::dump_spec(outputStream *st) const {
65 if (in(Address) == NULL) return; // node is dead
66 #ifndef ASSERT
67 // fake the missing field
68 const TypePtr* _adr_type = NULL;
69 if (in(Address) != NULL)
70 _adr_type = in(Address)->bottom_type()->isa_ptr();
71 #endif
72 dump_adr_type(this, _adr_type, st);
73
74 Compile* C = Compile::current();
75 if( C->alias_type(_adr_type)->is_volatile() )
76 st->print(" Volatile!");
77 }
78
79 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
80 st->print(" @");
81 if (adr_type == NULL) {
82 st->print("NULL");
83 } else {
84 adr_type->dump_on(st);
85 Compile* C = Compile::current();
86 Compile::AliasType* atp = NULL;
87 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
88 if (atp == NULL)
89 st->print(", idx=?\?;");
90 else if (atp->index() == Compile::AliasIdxBot)
91 st->print(", idx=Bot;");
92 else if (atp->index() == Compile::AliasIdxTop)
93 st->print(", idx=Top;");
94 else if (atp->index() == Compile::AliasIdxRaw)
95 st->print(", idx=Raw;");
96 else {
97 ciField* field = atp->field();
98 if (field) {
99 st->print(", name=");
100 field->print_name_on(st);
101 }
102 st->print(", idx=%d;", atp->index());
103 }
104 }
105 }
106
107 extern void print_alias_types();
108
109 #endif
110
111 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypeOopPtr *t_oop, Node *load, PhaseGVN *phase) {
112 assert((t_oop != NULL), "sanity");
113 bool is_instance = t_oop->is_known_instance_field();
114 bool is_boxed_value_load = t_oop->is_ptr_to_boxed_value() &&
115 (load != NULL) && load->is_Load() &&
116 (phase->is_IterGVN() != NULL);
117 if (!(is_instance || is_boxed_value_load))
118 return mchain; // don't try to optimize non-instance types
119 uint instance_id = t_oop->instance_id();
120 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
121 Node *prev = NULL;
122 Node *result = mchain;
123 while (prev != result) {
124 prev = result;
125 if (result == start_mem)
126 break; // hit one of our sentinels
127 // skip over a call which does not affect this memory slice
128 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
129 Node *proj_in = result->in(0);
130 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
131 break; // hit one of our sentinels
132 } else if (proj_in->is_Call()) {
133 // ArrayCopyNodes processed here as well
134 CallNode *call = proj_in->as_Call();
135 if (!call->may_modify(t_oop, phase)) { // returns false for instances
136 result = call->in(TypeFunc::Memory);
137 }
138 } else if (proj_in->is_Initialize()) {
139 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
140 // Stop if this is the initialization for the object instance which
141 // contains this memory slice, otherwise skip over it.
142 if ((alloc == NULL) || (alloc->_idx == instance_id)) {
143 break;
144 }
145 if (is_instance) {
146 result = proj_in->in(TypeFunc::Memory);
147 } else if (is_boxed_value_load) {
148 Node* klass = alloc->in(AllocateNode::KlassNode);
149 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
150 if (tklass->klass_is_exact() && !tklass->klass()->equals(t_oop->klass())) {
151 result = proj_in->in(TypeFunc::Memory); // not related allocation
152 }
153 }
154 } else if (proj_in->is_MemBar()) {
155 if (ArrayCopyNode::membar_for_arraycopy(t_oop, proj_in->as_MemBar(), phase)) {
156 break;
157 }
158 result = proj_in->in(TypeFunc::Memory);
159 } else {
160 assert(false, "unexpected projection");
161 }
162 } else if (result->is_ClearArray()) {
163 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
164 // Can not bypass initialization of the instance
165 // we are looking for.
166 break;
167 }
168 // Otherwise skip it (the call updated 'result' value).
169 } else if (result->is_MergeMem()) {
170 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, NULL, tty);
171 }
172 }
173 return result;
174 }
175
176 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
177 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
178 if (t_oop == NULL)
179 return mchain; // don't try to optimize non-oop types
180 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
181 bool is_instance = t_oop->is_known_instance_field();
182 PhaseIterGVN *igvn = phase->is_IterGVN();
183 if (is_instance && igvn != NULL && result->is_Phi()) {
184 PhiNode *mphi = result->as_Phi();
185 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
186 const TypePtr *t = mphi->adr_type();
187 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
188 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
189 t->is_oopptr()->cast_to_exactness(true)
190 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
191 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
192 // clone the Phi with our address type
193 result = mphi->split_out_instance(t_adr, igvn);
194 } else {
195 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
196 }
197 }
198 return result;
199 }
200
201 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
202 uint alias_idx = phase->C->get_alias_index(tp);
203 Node *mem = mmem;
204 #ifdef ASSERT
205 {
206 // Check that current type is consistent with the alias index used during graph construction
207 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
208 bool consistent = adr_check == NULL || adr_check->empty() ||
209 phase->C->must_alias(adr_check, alias_idx );
210 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
211 if( !consistent && adr_check != NULL && !adr_check->empty() &&
212 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
213 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
214 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
215 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
216 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
217 // don't assert if it is dead code.
218 consistent = true;
219 }
220 if( !consistent ) {
221 st->print("alias_idx==%d, adr_check==", alias_idx);
222 if( adr_check == NULL ) {
223 st->print("NULL");
224 } else {
225 adr_check->dump();
226 }
227 st->cr();
228 print_alias_types();
229 assert(consistent, "adr_check must match alias idx");
230 }
231 }
232 #endif
233 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
234 // means an array I have not precisely typed yet. Do not do any
235 // alias stuff with it any time soon.
236 const TypeOopPtr *toop = tp->isa_oopptr();
237 if( tp->base() != Type::AnyPtr &&
238 !(toop &&
239 toop->klass() != NULL &&
240 toop->klass()->is_java_lang_Object() &&
241 toop->offset() == Type::OffsetBot) ) {
242 // compress paths and change unreachable cycles to TOP
243 // If not, we can update the input infinitely along a MergeMem cycle
244 // Equivalent code in PhiNode::Ideal
245 Node* m = phase->transform(mmem);
246 // If transformed to a MergeMem, get the desired slice
247 // Otherwise the returned node represents memory for every slice
248 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
249 // Update input if it is progress over what we have now
250 }
251 return mem;
252 }
253
254 //--------------------------Ideal_common---------------------------------------
255 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
256 // Unhook non-raw memories from complete (macro-expanded) initializations.
257 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
258 // If our control input is a dead region, kill all below the region
259 Node *ctl = in(MemNode::Control);
260 if (ctl && remove_dead_region(phase, can_reshape))
261 return this;
262 ctl = in(MemNode::Control);
263 // Don't bother trying to transform a dead node
264 if (ctl && ctl->is_top()) return NodeSentinel;
265
266 PhaseIterGVN *igvn = phase->is_IterGVN();
267 // Wait if control on the worklist.
268 if (ctl && can_reshape && igvn != NULL) {
269 Node* bol = NULL;
270 Node* cmp = NULL;
271 if (ctl->in(0)->is_If()) {
272 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
273 bol = ctl->in(0)->in(1);
274 if (bol->is_Bool())
275 cmp = ctl->in(0)->in(1)->in(1);
276 }
277 if (igvn->_worklist.member(ctl) ||
278 (bol != NULL && igvn->_worklist.member(bol)) ||
279 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
280 // This control path may be dead.
281 // Delay this memory node transformation until the control is processed.
282 phase->is_IterGVN()->_worklist.push(this);
283 return NodeSentinel; // caller will return NULL
284 }
285 }
286 // Ignore if memory is dead, or self-loop
287 Node *mem = in(MemNode::Memory);
288 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return NULL
289 assert(mem != this, "dead loop in MemNode::Ideal");
290
291 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
292 // This memory slice may be dead.
293 // Delay this mem node transformation until the memory is processed.
294 phase->is_IterGVN()->_worklist.push(this);
295 return NodeSentinel; // caller will return NULL
296 }
297
298 Node *address = in(MemNode::Address);
299 const Type *t_adr = phase->type(address);
300 if (t_adr == Type::TOP) return NodeSentinel; // caller will return NULL
301
302 if (can_reshape && igvn != NULL &&
303 (igvn->_worklist.member(address) ||
304 igvn->_worklist.size() > 0 && (t_adr != adr_type())) ) {
305 // The address's base and type may change when the address is processed.
306 // Delay this mem node transformation until the address is processed.
307 phase->is_IterGVN()->_worklist.push(this);
308 return NodeSentinel; // caller will return NULL
309 }
310
311 // Do NOT remove or optimize the next lines: ensure a new alias index
312 // is allocated for an oop pointer type before Escape Analysis.
313 // Note: C++ will not remove it since the call has side effect.
314 if (t_adr->isa_oopptr()) {
315 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
316 }
317
318 Node* base = NULL;
319 if (address->is_AddP()) {
320 base = address->in(AddPNode::Base);
321 }
322 if (base != NULL && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
323 !t_adr->isa_rawptr()) {
324 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
325 // Skip this node optimization if its address has TOP base.
326 return NodeSentinel; // caller will return NULL
327 }
328
329 // Avoid independent memory operations
330 Node* old_mem = mem;
331
332 // The code which unhooks non-raw memories from complete (macro-expanded)
333 // initializations was removed. After macro-expansion all stores catched
334 // by Initialize node became raw stores and there is no information
335 // which memory slices they modify. So it is unsafe to move any memory
336 // operation above these stores. Also in most cases hooked non-raw memories
337 // were already unhooked by using information from detect_ptr_independence()
338 // and find_previous_store().
339
340 if (mem->is_MergeMem()) {
341 MergeMemNode* mmem = mem->as_MergeMem();
342 const TypePtr *tp = t_adr->is_ptr();
343
344 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
345 }
346
347 if (mem != old_mem) {
348 set_req(MemNode::Memory, mem);
349 if (can_reshape && old_mem->outcnt() == 0) {
350 igvn->_worklist.push(old_mem);
351 }
352 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
353 return this;
354 }
355
356 // let the subclass continue analyzing...
357 return NULL;
358 }
359
360 // Helper function for proving some simple control dominations.
361 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
362 // Already assumes that 'dom' is available at 'sub', and that 'sub'
363 // is not a constant (dominated by the method's StartNode).
364 // Used by MemNode::find_previous_store to prove that the
365 // control input of a memory operation predates (dominates)
366 // an allocation it wants to look past.
367 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
368 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
369 return false; // Conservative answer for dead code
370
371 // Check 'dom'. Skip Proj and CatchProj nodes.
372 dom = dom->find_exact_control(dom);
373 if (dom == NULL || dom->is_top())
374 return false; // Conservative answer for dead code
375
376 if (dom == sub) {
377 // For the case when, for example, 'sub' is Initialize and the original
378 // 'dom' is Proj node of the 'sub'.
379 return false;
380 }
381
382 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
383 return true;
384
385 // 'dom' dominates 'sub' if its control edge and control edges
386 // of all its inputs dominate or equal to sub's control edge.
387
388 // Currently 'sub' is either Allocate, Initialize or Start nodes.
389 // Or Region for the check in LoadNode::Ideal();
390 // 'sub' should have sub->in(0) != NULL.
391 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
392 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
393
394 // Get control edge of 'sub'.
395 Node* orig_sub = sub;
396 sub = sub->find_exact_control(sub->in(0));
397 if (sub == NULL || sub->is_top())
398 return false; // Conservative answer for dead code
399
400 assert(sub->is_CFG(), "expecting control");
401
402 if (sub == dom)
403 return true;
404
405 if (sub->is_Start() || sub->is_Root())
406 return false;
407
408 {
409 // Check all control edges of 'dom'.
410
411 ResourceMark rm;
412 Arena* arena = Thread::current()->resource_area();
413 Node_List nlist(arena);
414 Unique_Node_List dom_list(arena);
415
416 dom_list.push(dom);
417 bool only_dominating_controls = false;
418
419 for (uint next = 0; next < dom_list.size(); next++) {
420 Node* n = dom_list.at(next);
421 if (n == orig_sub)
422 return false; // One of dom's inputs dominated by sub.
423 if (!n->is_CFG() && n->pinned()) {
424 // Check only own control edge for pinned non-control nodes.
425 n = n->find_exact_control(n->in(0));
426 if (n == NULL || n->is_top())
427 return false; // Conservative answer for dead code
428 assert(n->is_CFG(), "expecting control");
429 dom_list.push(n);
430 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
431 only_dominating_controls = true;
432 } else if (n->is_CFG()) {
433 if (n->dominates(sub, nlist))
434 only_dominating_controls = true;
435 else
436 return false;
437 } else {
438 // First, own control edge.
439 Node* m = n->find_exact_control(n->in(0));
440 if (m != NULL) {
441 if (m->is_top())
442 return false; // Conservative answer for dead code
443 dom_list.push(m);
444 }
445 // Now, the rest of edges.
446 uint cnt = n->req();
447 for (uint i = 1; i < cnt; i++) {
448 m = n->find_exact_control(n->in(i));
449 if (m == NULL || m->is_top())
450 continue;
451 dom_list.push(m);
452 }
453 }
454 }
455 return only_dominating_controls;
456 }
457 }
458
459 //---------------------detect_ptr_independence---------------------------------
460 // Used by MemNode::find_previous_store to prove that two base
461 // pointers are never equal.
462 // The pointers are accompanied by their associated allocations,
463 // if any, which have been previously discovered by the caller.
464 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
465 Node* p2, AllocateNode* a2,
466 PhaseTransform* phase) {
467 // Attempt to prove that these two pointers cannot be aliased.
468 // They may both manifestly be allocations, and they should differ.
469 // Or, if they are not both allocations, they can be distinct constants.
470 // Otherwise, one is an allocation and the other a pre-existing value.
471 if (a1 == NULL && a2 == NULL) { // neither an allocation
472 return (p1 != p2) && p1->is_Con() && p2->is_Con();
473 } else if (a1 != NULL && a2 != NULL) { // both allocations
474 return (a1 != a2);
475 } else if (a1 != NULL) { // one allocation a1
476 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
477 return all_controls_dominate(p2, a1);
478 } else { //(a2 != NULL) // one allocation a2
479 return all_controls_dominate(p1, a2);
480 }
481 return false;
482 }
483
484
485 // Find an arraycopy that must have set (can_see_stored_value=true) or
486 // could have set (can_see_stored_value=false) the value for this load
487 Node* LoadNode::find_previous_arraycopy(PhaseTransform* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
488 if (mem->is_Proj() && mem->in(0) != NULL && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
489 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
490 Node* mb = mem->in(0);
491 if (mb->in(0) != NULL && mb->in(0)->is_Proj() &&
492 mb->in(0)->in(0) != NULL && mb->in(0)->in(0)->is_ArrayCopy()) {
493 ArrayCopyNode* ac = mb->in(0)->in(0)->as_ArrayCopy();
494 if (ac->is_clonebasic()) {
495 intptr_t offset;
496 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest), phase, offset);
497 assert(alloc != NULL && alloc->initialization()->is_complete_with_arraycopy(), "broken allocation");
498 if (alloc == ld_alloc) {
499 return ac;
500 }
501 }
502 }
503 } else if (mem->is_Proj() && mem->in(0) != NULL && mem->in(0)->is_ArrayCopy()) {
504 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
505
506 if (ac->is_arraycopy_validated() ||
507 ac->is_copyof_validated() ||
508 ac->is_copyofrange_validated()) {
509 Node* ld_addp = in(MemNode::Address);
510 if (ld_addp->is_AddP()) {
511 Node* ld_base = ld_addp->in(AddPNode::Address);
512 Node* ld_offs = ld_addp->in(AddPNode::Offset);
513
514 Node* dest = ac->in(ArrayCopyNode::Dest);
515
516 if (dest == ld_base) {
517 const TypeX *ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
518 if (ac->modifies(ld_offs_t->_lo, ld_offs_t->_hi, phase, can_see_stored_value)) {
519 return ac;
520 }
521 if (!can_see_stored_value) {
522 mem = ac->in(TypeFunc::Memory);
523 }
524 }
525 }
526 }
527 }
528 return NULL;
529 }
530
531 // The logic for reordering loads and stores uses four steps:
532 // (a) Walk carefully past stores and initializations which we
533 // can prove are independent of this load.
534 // (b) Observe that the next memory state makes an exact match
535 // with self (load or store), and locate the relevant store.
536 // (c) Ensure that, if we were to wire self directly to the store,
537 // the optimizer would fold it up somehow.
538 // (d) Do the rewiring, and return, depending on some other part of
539 // the optimizer to fold up the load.
540 // This routine handles steps (a) and (b). Steps (c) and (d) are
541 // specific to loads and stores, so they are handled by the callers.
542 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
543 //
544 Node* MemNode::find_previous_store(PhaseTransform* phase) {
545 Node* ctrl = in(MemNode::Control);
546 Node* adr = in(MemNode::Address);
547 intptr_t offset = 0;
548 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
549 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
550
551 if (offset == Type::OffsetBot)
552 return NULL; // cannot unalias unless there are precise offsets
553
554 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
555
556 intptr_t size_in_bytes = memory_size();
557
558 Node* mem = in(MemNode::Memory); // start searching here...
559
560 int cnt = 50; // Cycle limiter
561 for (;;) { // While we can dance past unrelated stores...
562 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
563
564 Node* prev = mem;
565 if (mem->is_Store()) {
566 Node* st_adr = mem->in(MemNode::Address);
567 intptr_t st_offset = 0;
568 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
569 if (st_base == NULL)
570 break; // inscrutable pointer
571 if (st_offset != offset && st_offset != Type::OffsetBot) {
572 const int MAX_STORE = BytesPerLong;
573 if (st_offset >= offset + size_in_bytes ||
574 st_offset <= offset - MAX_STORE ||
575 st_offset <= offset - mem->as_Store()->memory_size()) {
576 // Success: The offsets are provably independent.
577 // (You may ask, why not just test st_offset != offset and be done?
578 // The answer is that stores of different sizes can co-exist
579 // in the same sequence of RawMem effects. We sometimes initialize
580 // a whole 'tile' of array elements with a single jint or jlong.)
581 mem = mem->in(MemNode::Memory);
582 continue; // (a) advance through independent store memory
583 }
584 }
585 if (st_base != base &&
586 detect_ptr_independence(base, alloc,
587 st_base,
588 AllocateNode::Ideal_allocation(st_base, phase),
589 phase)) {
590 // Success: The bases are provably independent.
591 mem = mem->in(MemNode::Memory);
592 continue; // (a) advance through independent store memory
593 }
594
595 // (b) At this point, if the bases or offsets do not agree, we lose,
596 // since we have not managed to prove 'this' and 'mem' independent.
597 if (st_base == base && st_offset == offset) {
598 return mem; // let caller handle steps (c), (d)
599 }
600
601 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
602 InitializeNode* st_init = mem->in(0)->as_Initialize();
603 AllocateNode* st_alloc = st_init->allocation();
604 if (st_alloc == NULL)
605 break; // something degenerated
606 bool known_identical = false;
607 bool known_independent = false;
608 if (alloc == st_alloc)
609 known_identical = true;
610 else if (alloc != NULL)
611 known_independent = true;
612 else if (all_controls_dominate(this, st_alloc))
613 known_independent = true;
614
615 if (known_independent) {
616 // The bases are provably independent: Either they are
617 // manifestly distinct allocations, or else the control
618 // of this load dominates the store's allocation.
619 int alias_idx = phase->C->get_alias_index(adr_type());
620 if (alias_idx == Compile::AliasIdxRaw) {
621 mem = st_alloc->in(TypeFunc::Memory);
622 } else {
623 mem = st_init->memory(alias_idx);
624 }
625 continue; // (a) advance through independent store memory
626 }
627
628 // (b) at this point, if we are not looking at a store initializing
629 // the same allocation we are loading from, we lose.
630 if (known_identical) {
631 // From caller, can_see_stored_value will consult find_captured_store.
632 return mem; // let caller handle steps (c), (d)
633 }
634
635 } else if (find_previous_arraycopy(phase, alloc, mem, false) != NULL) {
636 if (prev != mem) {
637 // Found an arraycopy but it doesn't affect that load
638 continue;
639 }
640 // Found an arraycopy that may affect that load
641 return mem;
642 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
643 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
644 if (mem->is_Proj() && mem->in(0)->is_Call()) {
645 // ArrayCopyNodes processed here as well.
646 CallNode *call = mem->in(0)->as_Call();
647 if (!call->may_modify(addr_t, phase)) {
648 mem = call->in(TypeFunc::Memory);
649 continue; // (a) advance through independent call memory
650 }
651 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
652 if (ArrayCopyNode::membar_for_arraycopy(addr_t, mem->in(0)->as_MemBar(), phase)) {
653 break;
654 }
655 mem = mem->in(0)->in(TypeFunc::Memory);
656 continue; // (a) advance through independent MemBar memory
657 } else if (mem->is_ClearArray()) {
658 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
659 // (the call updated 'mem' value)
660 continue; // (a) advance through independent allocation memory
661 } else {
662 // Can not bypass initialization of the instance
663 // we are looking for.
664 return mem;
665 }
666 } else if (mem->is_MergeMem()) {
667 int alias_idx = phase->C->get_alias_index(adr_type());
668 mem = mem->as_MergeMem()->memory_at(alias_idx);
669 continue; // (a) advance through independent MergeMem memory
670 }
671 }
672
673 // Unless there is an explicit 'continue', we must bail out here,
674 // because 'mem' is an inscrutable memory state (e.g., a call).
675 break;
676 }
677
678 return NULL; // bail out
679 }
680
681 //----------------------calculate_adr_type-------------------------------------
682 // Helper function. Notices when the given type of address hits top or bottom.
683 // Also, asserts a cross-check of the type against the expected address type.
684 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
685 if (t == Type::TOP) return NULL; // does not touch memory any more?
686 #ifdef PRODUCT
687 cross_check = NULL;
688 #else
689 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
690 #endif
691 const TypePtr* tp = t->isa_ptr();
692 if (tp == NULL) {
693 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
694 return TypePtr::BOTTOM; // touches lots of memory
695 } else {
696 #ifdef ASSERT
697 // %%%% [phh] We don't check the alias index if cross_check is
698 // TypeRawPtr::BOTTOM. Needs to be investigated.
699 if (cross_check != NULL &&
700 cross_check != TypePtr::BOTTOM &&
701 cross_check != TypeRawPtr::BOTTOM) {
702 // Recheck the alias index, to see if it has changed (due to a bug).
703 Compile* C = Compile::current();
704 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
705 "must stay in the original alias category");
706 // The type of the address must be contained in the adr_type,
707 // disregarding "null"-ness.
708 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
709 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
710 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
711 "real address must not escape from expected memory type");
712 }
713 #endif
714 return tp;
715 }
716 }
717
718 //=============================================================================
719 // Should LoadNode::Ideal() attempt to remove control edges?
720 bool LoadNode::can_remove_control() const {
721 return true;
722 }
723 uint LoadNode::size_of() const { return sizeof(*this); }
724 uint LoadNode::cmp( const Node &n ) const
725 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
726 const Type *LoadNode::bottom_type() const { return _type; }
727 uint LoadNode::ideal_reg() const {
728 return _type->ideal_reg();
729 }
730
731 #ifndef PRODUCT
732 void LoadNode::dump_spec(outputStream *st) const {
733 MemNode::dump_spec(st);
734 if( !Verbose && !WizardMode ) {
735 // standard dump does this in Verbose and WizardMode
736 st->print(" #"); _type->dump_on(st);
737 }
738 if (!_depends_only_on_test) {
739 st->print(" (does not depend only on test)");
740 }
741 }
742 #endif
743
744 #ifdef ASSERT
745 //----------------------------is_immutable_value-------------------------------
746 // Helper function to allow a raw load without control edge for some cases
747 bool LoadNode::is_immutable_value(Node* adr) {
748 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
749 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
750 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
751 in_bytes(JavaThread::osthread_offset())));
752 }
753 #endif
754
755 //----------------------------LoadNode::make-----------------------------------
756 // Polymorphic factory method:
757 Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, ControlDependency control_dependency) {
758 Compile* C = gvn.C;
759
760 // sanity check the alias category against the created node type
761 assert(!(adr_type->isa_oopptr() &&
762 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
763 "use LoadKlassNode instead");
764 assert(!(adr_type->isa_aryptr() &&
765 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
766 "use LoadRangeNode instead");
767 // Check control edge of raw loads
768 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
769 // oop will be recorded in oop map if load crosses safepoint
770 rt->isa_oopptr() || is_immutable_value(adr),
771 "raw memory operations should have control edge");
772 switch (bt) {
773 case T_BOOLEAN: return new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
774 case T_BYTE: return new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
775 case T_INT: return new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
776 case T_CHAR: return new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
777 case T_SHORT: return new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency);
778 case T_LONG: return new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
779 case T_FLOAT: return new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
780 case T_DOUBLE: return new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency);
781 case T_ADDRESS: return new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
782 case T_OBJECT:
783 #ifdef _LP64
784 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
785 Node* load = gvn.transform(new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
786 return new DecodeNNode(load, load->bottom_type()->make_ptr());
787 } else
788 #endif
789 {
790 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
791 return new LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
792 }
793 }
794 ShouldNotReachHere();
795 return (LoadNode*)NULL;
796 }
797
798 LoadLNode* LoadLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
799 bool require_atomic = true;
800 return new LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
801 }
802
803 LoadDNode* LoadDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
804 bool require_atomic = true;
805 return new LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
806 }
807
808
809
810 //------------------------------hash-------------------------------------------
811 uint LoadNode::hash() const {
812 // unroll addition of interesting fields
813 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
814 }
815
816 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
817 if ((atp != NULL) && (atp->index() >= Compile::AliasIdxRaw)) {
818 bool non_volatile = (atp->field() != NULL) && !atp->field()->is_volatile();
819 bool is_stable_ary = FoldStableValues &&
820 (tp != NULL) && (tp->isa_aryptr() != NULL) &&
821 tp->isa_aryptr()->is_stable();
822
823 return (eliminate_boxing && non_volatile) || is_stable_ary;
824 }
825
826 return false;
827 }
828
829 // Is the value loaded previously stored by an arraycopy? If so return
830 // a load node that reads from the source array so we may be able to
831 // optimize out the ArrayCopy node later.
832 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseTransform* phase) const {
833 Node* ld_adr = in(MemNode::Address);
834 intptr_t ld_off = 0;
835 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
836 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
837 if (ac != NULL) {
838 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
839
840 Node* ld = clone();
841 if (ac->as_ArrayCopy()->is_clonebasic()) {
842 assert(ld_alloc != NULL, "need an alloc");
843 Node* addp = in(MemNode::Address)->clone();
844 assert(addp->is_AddP(), "address must be addp");
845 assert(addp->in(AddPNode::Base) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Base), "strange pattern");
846 assert(addp->in(AddPNode::Address) == ac->in(ArrayCopyNode::Dest)->in(AddPNode::Address), "strange pattern");
847 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src)->in(AddPNode::Base));
848 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src)->in(AddPNode::Address));
849 ld->set_req(MemNode::Address, phase->transform(addp));
850 if (in(0) != NULL) {
851 assert(ld_alloc->in(0) != NULL, "alloc must have control");
852 ld->set_req(0, ld_alloc->in(0));
853 }
854 } else {
855 Node* addp = in(MemNode::Address)->clone();
856 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
857 addp->set_req(AddPNode::Base, ac->in(ArrayCopyNode::Src));
858 addp->set_req(AddPNode::Address, ac->in(ArrayCopyNode::Src));
859
860 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
861 BasicType ary_elem = ary_t->klass()->as_array_klass()->element_type()->basic_type();
862 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
863 uint shift = exact_log2(type2aelembytes(ary_elem));
864
865 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
866 #ifdef _LP64
867 diff = phase->transform(new ConvI2LNode(diff));
868 #endif
869 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
870
871 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
872 addp->set_req(AddPNode::Offset, offset);
873 ld->set_req(MemNode::Address, phase->transform(addp));
874
875 if (in(0) != NULL) {
876 assert(ac->in(0) != NULL, "alloc must have control");
877 ld->set_req(0, ac->in(0));
878 }
879 }
880 // load depends on the tests that validate the arraycopy
881 ld->as_Load()->_depends_only_on_test = Pinned;
882 return ld;
883 }
884 return NULL;
885 }
886
887
888 //---------------------------can_see_stored_value------------------------------
889 // This routine exists to make sure this set of tests is done the same
890 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
891 // will change the graph shape in a way which makes memory alive twice at the
892 // same time (uses the Oracle model of aliasing), then some
893 // LoadXNode::Identity will fold things back to the equivalence-class model
894 // of aliasing.
895 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
896 Node* ld_adr = in(MemNode::Address);
897 intptr_t ld_off = 0;
898 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
899 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
900 Compile::AliasType* atp = (tp != NULL) ? phase->C->alias_type(tp) : NULL;
901 // This is more general than load from boxing objects.
902 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
903 uint alias_idx = atp->index();
904 bool final = !atp->is_rewritable();
905 Node* result = NULL;
906 Node* current = st;
907 // Skip through chains of MemBarNodes checking the MergeMems for
908 // new states for the slice of this load. Stop once any other
909 // kind of node is encountered. Loads from final memory can skip
910 // through any kind of MemBar but normal loads shouldn't skip
911 // through MemBarAcquire since the could allow them to move out of
912 // a synchronized region.
913 while (current->is_Proj()) {
914 int opc = current->in(0)->Opcode();
915 if ((final && (opc == Op_MemBarAcquire ||
916 opc == Op_MemBarAcquireLock ||
917 opc == Op_LoadFence)) ||
918 opc == Op_MemBarRelease ||
919 opc == Op_StoreFence ||
920 opc == Op_MemBarReleaseLock ||
921 opc == Op_MemBarStoreStore ||
922 opc == Op_MemBarCPUOrder) {
923 Node* mem = current->in(0)->in(TypeFunc::Memory);
924 if (mem->is_MergeMem()) {
925 MergeMemNode* merge = mem->as_MergeMem();
926 Node* new_st = merge->memory_at(alias_idx);
927 if (new_st == merge->base_memory()) {
928 // Keep searching
929 current = new_st;
930 continue;
931 }
932 // Save the new memory state for the slice and fall through
933 // to exit.
934 result = new_st;
935 }
936 }
937 break;
938 }
939 if (result != NULL) {
940 st = result;
941 }
942 }
943
944 // Loop around twice in the case Load -> Initialize -> Store.
945 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
946 for (int trip = 0; trip <= 1; trip++) {
947
948 if (st->is_Store()) {
949 Node* st_adr = st->in(MemNode::Address);
950 if (!phase->eqv(st_adr, ld_adr)) {
951 // Try harder before giving up... Match raw and non-raw pointers.
952 intptr_t st_off = 0;
953 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
954 if (alloc == NULL) return NULL;
955 if (alloc != ld_alloc) return NULL;
956 if (ld_off != st_off) return NULL;
957 // At this point we have proven something like this setup:
958 // A = Allocate(...)
959 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
960 // S = StoreQ(, AddP(, A.Parm , #Off), V)
961 // (Actually, we haven't yet proven the Q's are the same.)
962 // In other words, we are loading from a casted version of
963 // the same pointer-and-offset that we stored to.
964 // Thus, we are able to replace L by V.
965 }
966 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
967 if (store_Opcode() != st->Opcode())
968 return NULL;
969 return st->in(MemNode::ValueIn);
970 }
971
972 // A load from a freshly-created object always returns zero.
973 // (This can happen after LoadNode::Ideal resets the load's memory input
974 // to find_captured_store, which returned InitializeNode::zero_memory.)
975 if (st->is_Proj() && st->in(0)->is_Allocate() &&
976 (st->in(0) == ld_alloc) &&
977 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
978 // return a zero value for the load's basic type
979 // (This is one of the few places where a generic PhaseTransform
980 // can create new nodes. Think of it as lazily manifesting
981 // virtually pre-existing constants.)
982 return phase->zerocon(memory_type());
983 }
984
985 // A load from an initialization barrier can match a captured store.
986 if (st->is_Proj() && st->in(0)->is_Initialize()) {
987 InitializeNode* init = st->in(0)->as_Initialize();
988 AllocateNode* alloc = init->allocation();
989 if ((alloc != NULL) && (alloc == ld_alloc)) {
990 // examine a captured store value
991 st = init->find_captured_store(ld_off, memory_size(), phase);
992 if (st != NULL) {
993 continue; // take one more trip around
994 }
995 }
996 }
997
998 // Load boxed value from result of valueOf() call is input parameter.
999 if (this->is_Load() && ld_adr->is_AddP() &&
1000 (tp != NULL) && tp->is_ptr_to_boxed_value()) {
1001 intptr_t ignore = 0;
1002 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1003 if (base != NULL && base->is_Proj() &&
1004 base->as_Proj()->_con == TypeFunc::Parms &&
1005 base->in(0)->is_CallStaticJava() &&
1006 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1007 return base->in(0)->in(TypeFunc::Parms);
1008 }
1009 }
1010
1011 break;
1012 }
1013
1014 return NULL;
1015 }
1016
1017 //----------------------is_instance_field_load_with_local_phi------------------
1018 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1019 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1020 in(Address)->is_AddP() ) {
1021 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1022 // Only instances and boxed values.
1023 if( t_oop != NULL &&
1024 (t_oop->is_ptr_to_boxed_value() ||
1025 t_oop->is_known_instance_field()) &&
1026 t_oop->offset() != Type::OffsetBot &&
1027 t_oop->offset() != Type::OffsetTop) {
1028 return true;
1029 }
1030 }
1031 return false;
1032 }
1033
1034 //------------------------------Identity---------------------------------------
1035 // Loads are identity if previous store is to same address
1036 Node *LoadNode::Identity( PhaseTransform *phase ) {
1037 // If the previous store-maker is the right kind of Store, and the store is
1038 // to the same address, then we are equal to the value stored.
1039 Node* mem = in(Memory);
1040 Node* value = can_see_stored_value(mem, phase);
1041 if( value ) {
1042 // byte, short & char stores truncate naturally.
1043 // A load has to load the truncated value which requires
1044 // some sort of masking operation and that requires an
1045 // Ideal call instead of an Identity call.
1046 if (memory_size() < BytesPerInt) {
1047 // If the input to the store does not fit with the load's result type,
1048 // it must be truncated via an Ideal call.
1049 if (!phase->type(value)->higher_equal(phase->type(this)))
1050 return this;
1051 }
1052 // (This works even when value is a Con, but LoadNode::Value
1053 // usually runs first, producing the singleton type of the Con.)
1054 return value;
1055 }
1056
1057 // Search for an existing data phi which was generated before for the same
1058 // instance's field to avoid infinite generation of phis in a loop.
1059 Node *region = mem->in(0);
1060 if (is_instance_field_load_with_local_phi(region)) {
1061 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1062 int this_index = phase->C->get_alias_index(addr_t);
1063 int this_offset = addr_t->offset();
1064 int this_iid = addr_t->instance_id();
1065 if (!addr_t->is_known_instance() &&
1066 addr_t->is_ptr_to_boxed_value()) {
1067 // Use _idx of address base (could be Phi node) for boxed values.
1068 intptr_t ignore = 0;
1069 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1070 this_iid = base->_idx;
1071 }
1072 const Type* this_type = bottom_type();
1073 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1074 Node* phi = region->fast_out(i);
1075 if (phi->is_Phi() && phi != mem &&
1076 phi->as_Phi()->is_same_inst_field(this_type, this_iid, this_index, this_offset)) {
1077 return phi;
1078 }
1079 }
1080 }
1081
1082 return this;
1083 }
1084
1085 // We're loading from an object which has autobox behaviour.
1086 // If this object is result of a valueOf call we'll have a phi
1087 // merging a newly allocated object and a load from the cache.
1088 // We want to replace this load with the original incoming
1089 // argument to the valueOf call.
1090 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1091 assert(phase->C->eliminate_boxing(), "sanity");
1092 intptr_t ignore = 0;
1093 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1094 if ((base == NULL) || base->is_Phi()) {
1095 // Push the loads from the phi that comes from valueOf up
1096 // through it to allow elimination of the loads and the recovery
1097 // of the original value. It is done in split_through_phi().
1098 return NULL;
1099 } else if (base->is_Load() ||
1100 base->is_DecodeN() && base->in(1)->is_Load()) {
1101 // Eliminate the load of boxed value for integer types from the cache
1102 // array by deriving the value from the index into the array.
1103 // Capture the offset of the load and then reverse the computation.
1104
1105 // Get LoadN node which loads a boxing object from 'cache' array.
1106 if (base->is_DecodeN()) {
1107 base = base->in(1);
1108 }
1109 if (!base->in(Address)->is_AddP()) {
1110 return NULL; // Complex address
1111 }
1112 AddPNode* address = base->in(Address)->as_AddP();
1113 Node* cache_base = address->in(AddPNode::Base);
1114 if ((cache_base != NULL) && cache_base->is_DecodeN()) {
1115 // Get ConP node which is static 'cache' field.
1116 cache_base = cache_base->in(1);
1117 }
1118 if ((cache_base != NULL) && cache_base->is_Con()) {
1119 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1120 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1121 Node* elements[4];
1122 int shift = exact_log2(type2aelembytes(T_OBJECT));
1123 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1124 if ((count > 0) && elements[0]->is_Con() &&
1125 ((count == 1) ||
1126 (count == 2) && elements[1]->Opcode() == Op_LShiftX &&
1127 elements[1]->in(2) == phase->intcon(shift))) {
1128 ciObjArray* array = base_type->const_oop()->as_obj_array();
1129 // Fetch the box object cache[0] at the base of the array and get its value
1130 ciInstance* box = array->obj_at(0)->as_instance();
1131 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1132 assert(ik->is_box_klass(), "sanity");
1133 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1134 if (ik->nof_nonstatic_fields() == 1) {
1135 // This should be true nonstatic_field_at requires calling
1136 // nof_nonstatic_fields so check it anyway
1137 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1138 BasicType bt = c.basic_type();
1139 // Only integer types have boxing cache.
1140 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1141 bt == T_BYTE || bt == T_SHORT ||
1142 bt == T_INT || bt == T_LONG, err_msg_res("wrong type = %s", type2name(bt)));
1143 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1144 if (cache_low != (int)cache_low) {
1145 return NULL; // should not happen since cache is array indexed by value
1146 }
1147 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1148 if (offset != (int)offset) {
1149 return NULL; // should not happen since cache is array indexed by value
1150 }
1151 // Add up all the offsets making of the address of the load
1152 Node* result = elements[0];
1153 for (int i = 1; i < count; i++) {
1154 result = phase->transform(new AddXNode(result, elements[i]));
1155 }
1156 // Remove the constant offset from the address and then
1157 result = phase->transform(new AddXNode(result, phase->MakeConX(-(int)offset)));
1158 // remove the scaling of the offset to recover the original index.
1159 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1160 // Peel the shift off directly but wrap it in a dummy node
1161 // since Ideal can't return existing nodes
1162 result = new RShiftXNode(result->in(1), phase->intcon(0));
1163 } else if (result->is_Add() && result->in(2)->is_Con() &&
1164 result->in(1)->Opcode() == Op_LShiftX &&
1165 result->in(1)->in(2) == phase->intcon(shift)) {
1166 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1167 // but for boxing cache access we know that X<<Z will not overflow
1168 // (there is range check) so we do this optimizatrion by hand here.
1169 Node* add_con = new RShiftXNode(result->in(2), phase->intcon(shift));
1170 result = new AddXNode(result->in(1)->in(1), phase->transform(add_con));
1171 } else {
1172 result = new RShiftXNode(result, phase->intcon(shift));
1173 }
1174 #ifdef _LP64
1175 if (bt != T_LONG) {
1176 result = new ConvL2INode(phase->transform(result));
1177 }
1178 #else
1179 if (bt == T_LONG) {
1180 result = new ConvI2LNode(phase->transform(result));
1181 }
1182 #endif
1183 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1184 // Need to preserve unboxing load type if it is unsigned.
1185 switch(this->Opcode()) {
1186 case Op_LoadUB:
1187 result = new AndINode(phase->transform(result), phase->intcon(0xFF));
1188 break;
1189 case Op_LoadUS:
1190 result = new AndINode(phase->transform(result), phase->intcon(0xFFFF));
1191 break;
1192 }
1193 return result;
1194 }
1195 }
1196 }
1197 }
1198 }
1199 return NULL;
1200 }
1201
1202 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1203 Node* region = phi->in(0);
1204 if (region == NULL) {
1205 return false; // Wait stable graph
1206 }
1207 uint cnt = phi->req();
1208 for (uint i = 1; i < cnt; i++) {
1209 Node* rc = region->in(i);
1210 if (rc == NULL || phase->type(rc) == Type::TOP)
1211 return false; // Wait stable graph
1212 Node* in = phi->in(i);
1213 if (in == NULL || phase->type(in) == Type::TOP)
1214 return false; // Wait stable graph
1215 }
1216 return true;
1217 }
1218 //------------------------------split_through_phi------------------------------
1219 // Split instance or boxed field load through Phi.
1220 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1221 Node* mem = in(Memory);
1222 Node* address = in(Address);
1223 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1224
1225 assert((t_oop != NULL) &&
1226 (t_oop->is_known_instance_field() ||
1227 t_oop->is_ptr_to_boxed_value()), "invalide conditions");
1228
1229 Compile* C = phase->C;
1230 intptr_t ignore = 0;
1231 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1232 bool base_is_phi = (base != NULL) && base->is_Phi();
1233 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1234 (base != NULL) && (base == address->in(AddPNode::Base)) &&
1235 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1236
1237 if (!((mem->is_Phi() || base_is_phi) &&
1238 (load_boxed_values || t_oop->is_known_instance_field()))) {
1239 return NULL; // memory is not Phi
1240 }
1241
1242 if (mem->is_Phi()) {
1243 if (!stable_phi(mem->as_Phi(), phase)) {
1244 return NULL; // Wait stable graph
1245 }
1246 uint cnt = mem->req();
1247 // Check for loop invariant memory.
1248 if (cnt == 3) {
1249 for (uint i = 1; i < cnt; i++) {
1250 Node* in = mem->in(i);
1251 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1252 if (m == mem) {
1253 set_req(Memory, mem->in(cnt - i));
1254 return this; // made change
1255 }
1256 }
1257 }
1258 }
1259 if (base_is_phi) {
1260 if (!stable_phi(base->as_Phi(), phase)) {
1261 return NULL; // Wait stable graph
1262 }
1263 uint cnt = base->req();
1264 // Check for loop invariant memory.
1265 if (cnt == 3) {
1266 for (uint i = 1; i < cnt; i++) {
1267 if (base->in(i) == base) {
1268 return NULL; // Wait stable graph
1269 }
1270 }
1271 }
1272 }
1273
1274 bool load_boxed_phi = load_boxed_values && base_is_phi && (base->in(0) == mem->in(0));
1275
1276 // Split through Phi (see original code in loopopts.cpp).
1277 assert(C->have_alias_type(t_oop), "instance should have alias type");
1278
1279 // Do nothing here if Identity will find a value
1280 // (to avoid infinite chain of value phis generation).
1281 if (!phase->eqv(this, this->Identity(phase)))
1282 return NULL;
1283
1284 // Select Region to split through.
1285 Node* region;
1286 if (!base_is_phi) {
1287 assert(mem->is_Phi(), "sanity");
1288 region = mem->in(0);
1289 // Skip if the region dominates some control edge of the address.
1290 if (!MemNode::all_controls_dominate(address, region))
1291 return NULL;
1292 } else if (!mem->is_Phi()) {
1293 assert(base_is_phi, "sanity");
1294 region = base->in(0);
1295 // Skip if the region dominates some control edge of the memory.
1296 if (!MemNode::all_controls_dominate(mem, region))
1297 return NULL;
1298 } else if (base->in(0) != mem->in(0)) {
1299 assert(base_is_phi && mem->is_Phi(), "sanity");
1300 if (MemNode::all_controls_dominate(mem, base->in(0))) {
1301 region = base->in(0);
1302 } else if (MemNode::all_controls_dominate(address, mem->in(0))) {
1303 region = mem->in(0);
1304 } else {
1305 return NULL; // complex graph
1306 }
1307 } else {
1308 assert(base->in(0) == mem->in(0), "sanity");
1309 region = mem->in(0);
1310 }
1311
1312 const Type* this_type = this->bottom_type();
1313 int this_index = C->get_alias_index(t_oop);
1314 int this_offset = t_oop->offset();
1315 int this_iid = t_oop->instance_id();
1316 if (!t_oop->is_known_instance() && load_boxed_values) {
1317 // Use _idx of address base for boxed values.
1318 this_iid = base->_idx;
1319 }
1320 PhaseIterGVN* igvn = phase->is_IterGVN();
1321 Node* phi = new PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1322 for (uint i = 1; i < region->req(); i++) {
1323 Node* x;
1324 Node* the_clone = NULL;
1325 if (region->in(i) == C->top()) {
1326 x = C->top(); // Dead path? Use a dead data op
1327 } else {
1328 x = this->clone(); // Else clone up the data op
1329 the_clone = x; // Remember for possible deletion.
1330 // Alter data node to use pre-phi inputs
1331 if (this->in(0) == region) {
1332 x->set_req(0, region->in(i));
1333 } else {
1334 x->set_req(0, NULL);
1335 }
1336 if (mem->is_Phi() && (mem->in(0) == region)) {
1337 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1338 }
1339 if (address->is_Phi() && address->in(0) == region) {
1340 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1341 }
1342 if (base_is_phi && (base->in(0) == region)) {
1343 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1344 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1345 x->set_req(Address, adr_x);
1346 }
1347 }
1348 // Check for a 'win' on some paths
1349 const Type *t = x->Value(igvn);
1350
1351 bool singleton = t->singleton();
1352
1353 // See comments in PhaseIdealLoop::split_thru_phi().
1354 if (singleton && t == Type::TOP) {
1355 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1356 }
1357
1358 if (singleton) {
1359 x = igvn->makecon(t);
1360 } else {
1361 // We now call Identity to try to simplify the cloned node.
1362 // Note that some Identity methods call phase->type(this).
1363 // Make sure that the type array is big enough for
1364 // our new node, even though we may throw the node away.
1365 // (This tweaking with igvn only works because x is a new node.)
1366 igvn->set_type(x, t);
1367 // If x is a TypeNode, capture any more-precise type permanently into Node
1368 // otherwise it will be not updated during igvn->transform since
1369 // igvn->type(x) is set to x->Value() already.
1370 x->raise_bottom_type(t);
1371 Node *y = x->Identity(igvn);
1372 if (y != x) {
1373 x = y;
1374 } else {
1375 y = igvn->hash_find_insert(x);
1376 if (y) {
1377 x = y;
1378 } else {
1379 // Else x is a new node we are keeping
1380 // We do not need register_new_node_with_optimizer
1381 // because set_type has already been called.
1382 igvn->_worklist.push(x);
1383 }
1384 }
1385 }
1386 if (x != the_clone && the_clone != NULL) {
1387 igvn->remove_dead_node(the_clone);
1388 }
1389 phi->set_req(i, x);
1390 }
1391 // Record Phi
1392 igvn->register_new_node_with_optimizer(phi);
1393 return phi;
1394 }
1395
1396 //------------------------------Ideal------------------------------------------
1397 // If the load is from Field memory and the pointer is non-null, it might be possible to
1398 // zero out the control input.
1399 // If the offset is constant and the base is an object allocation,
1400 // try to hook me up to the exact initializing store.
1401 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1402 Node* p = MemNode::Ideal_common(phase, can_reshape);
1403 if (p) return (p == NodeSentinel) ? NULL : p;
1404
1405 Node* ctrl = in(MemNode::Control);
1406 Node* address = in(MemNode::Address);
1407 bool progress = false;
1408
1409 // Skip up past a SafePoint control. Cannot do this for Stores because
1410 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1411 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1412 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1413 ctrl = ctrl->in(0);
1414 set_req(MemNode::Control,ctrl);
1415 progress = true;
1416 }
1417
1418 intptr_t ignore = 0;
1419 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1420 if (base != NULL
1421 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1422 // Check for useless control edge in some common special cases
1423 if (in(MemNode::Control) != NULL
1424 && can_remove_control()
1425 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1426 && all_controls_dominate(base, phase->C->start())) {
1427 // A method-invariant, non-null address (constant or 'this' argument).
1428 set_req(MemNode::Control, NULL);
1429 progress = true;
1430 }
1431 }
1432
1433 Node* mem = in(MemNode::Memory);
1434 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1435
1436 if (can_reshape && (addr_t != NULL)) {
1437 // try to optimize our memory input
1438 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
1439 if (opt_mem != mem) {
1440 set_req(MemNode::Memory, opt_mem);
1441 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1442 return this;
1443 }
1444 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1445 if ((t_oop != NULL) &&
1446 (t_oop->is_known_instance_field() ||
1447 t_oop->is_ptr_to_boxed_value())) {
1448 PhaseIterGVN *igvn = phase->is_IterGVN();
1449 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1450 // Delay this transformation until memory Phi is processed.
1451 phase->is_IterGVN()->_worklist.push(this);
1452 return NULL;
1453 }
1454 // Split instance field load through Phi.
1455 Node* result = split_through_phi(phase);
1456 if (result != NULL) return result;
1457
1458 if (t_oop->is_ptr_to_boxed_value()) {
1459 Node* result = eliminate_autobox(phase);
1460 if (result != NULL) return result;
1461 }
1462 }
1463 }
1464
1465 // Is there a dominating load that loads the same value? Leave
1466 // anything that is not a load of a field/array element (like
1467 // barriers etc.) alone
1468 if (in(0) != NULL && adr_type() != TypeRawPtr::BOTTOM && can_reshape) {
1469 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
1470 Node *use = mem->fast_out(i);
1471 if (use != this &&
1472 use->Opcode() == Opcode() &&
1473 use->in(0) != NULL &&
1474 use->in(0) != in(0) &&
1475 use->in(Address) == in(Address)) {
1476 Node* ctl = in(0);
1477 for (int i = 0; i < 10 && ctl != NULL; i++) {
1478 ctl = IfNode::up_one_dom(ctl);
1479 if (ctl == use->in(0)) {
1480 set_req(0, use->in(0));
1481 return this;
1482 }
1483 }
1484 }
1485 }
1486 }
1487
1488 // Check for prior store with a different base or offset; make Load
1489 // independent. Skip through any number of them. Bail out if the stores
1490 // are in an endless dead cycle and report no progress. This is a key
1491 // transform for Reflection. However, if after skipping through the Stores
1492 // we can't then fold up against a prior store do NOT do the transform as
1493 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1494 // array memory alive twice: once for the hoisted Load and again after the
1495 // bypassed Store. This situation only works if EVERYBODY who does
1496 // anti-dependence work knows how to bypass. I.e. we need all
1497 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1498 // the alias index stuff. So instead, peek through Stores and IFF we can
1499 // fold up, do so.
1500 Node* prev_mem = find_previous_store(phase);
1501 if (prev_mem != NULL) {
1502 Node* value = can_see_arraycopy_value(prev_mem, phase);
1503 if (value != NULL) {
1504 return value;
1505 }
1506 }
1507 // Steps (a), (b): Walk past independent stores to find an exact match.
1508 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1509 // (c) See if we can fold up on the spot, but don't fold up here.
1510 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1511 // just return a prior value, which is done by Identity calls.
1512 if (can_see_stored_value(prev_mem, phase)) {
1513 // Make ready for step (d):
1514 set_req(MemNode::Memory, prev_mem);
1515 return this;
1516 }
1517 }
1518
1519 return progress ? this : NULL;
1520 }
1521
1522 // Helper to recognize certain Klass fields which are invariant across
1523 // some group of array types (e.g., int[] or all T[] where T < Object).
1524 const Type*
1525 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1526 ciKlass* klass) const {
1527 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1528 // The field is Klass::_modifier_flags. Return its (constant) value.
1529 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1530 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1531 return TypeInt::make(klass->modifier_flags());
1532 }
1533 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1534 // The field is Klass::_access_flags. Return its (constant) value.
1535 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1536 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1537 return TypeInt::make(klass->access_flags());
1538 }
1539 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1540 // The field is Klass::_layout_helper. Return its constant value if known.
1541 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1542 return TypeInt::make(klass->layout_helper());
1543 }
1544
1545 // No match.
1546 return NULL;
1547 }
1548
1549 // Try to constant-fold a stable array element.
1550 static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
1551 assert(ary->const_oop(), "array should be constant");
1552 assert(ary->is_stable(), "array should be stable");
1553
1554 // Decode the results of GraphKit::array_element_address.
1555 ciArray* aobj = ary->const_oop()->as_array();
1556 ciConstant con = aobj->element_value_by_offset(off);
1557
1558 if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
1559 const Type* con_type = Type::make_from_constant(con);
1560 if (con_type != NULL) {
1561 if (con_type->isa_aryptr()) {
1562 // Join with the array element type, in case it is also stable.
1563 int dim = ary->stable_dimension();
1564 con_type = con_type->is_aryptr()->cast_to_stable(true, dim-1);
1565 }
1566 if (loadbt == T_NARROWOOP && con_type->isa_oopptr()) {
1567 con_type = con_type->make_narrowoop();
1568 }
1569 #ifndef PRODUCT
1570 if (TraceIterativeGVN) {
1571 tty->print("FoldStableValues: array element [off=%d]: con_type=", off);
1572 con_type->dump(); tty->cr();
1573 }
1574 #endif //PRODUCT
1575 return con_type;
1576 }
1577 }
1578 return NULL;
1579 }
1580
1581 //------------------------------Value-----------------------------------------
1582 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1583 // Either input is TOP ==> the result is TOP
1584 Node* mem = in(MemNode::Memory);
1585 const Type *t1 = phase->type(mem);
1586 if (t1 == Type::TOP) return Type::TOP;
1587 Node* adr = in(MemNode::Address);
1588 const TypePtr* tp = phase->type(adr)->isa_ptr();
1589 if (tp == NULL || tp->empty()) return Type::TOP;
1590 int off = tp->offset();
1591 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1592 Compile* C = phase->C;
1593
1594 // Try to guess loaded type from pointer type
1595 if (tp->isa_aryptr()) {
1596 const TypeAryPtr* ary = tp->is_aryptr();
1597 const Type* t = ary->elem();
1598
1599 // Determine whether the reference is beyond the header or not, by comparing
1600 // the offset against the offset of the start of the array's data.
1601 // Different array types begin at slightly different offsets (12 vs. 16).
1602 // We choose T_BYTE as an example base type that is least restrictive
1603 // as to alignment, which will therefore produce the smallest
1604 // possible base offset.
1605 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1606 const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
1607
1608 // Try to constant-fold a stable array element.
1609 if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
1610 // Make sure the reference is not into the header and the offset is constant
1611 if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
1612 const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());
1613 if (con_type != NULL) {
1614 return con_type;
1615 }
1616 }
1617 }
1618
1619 // Don't do this for integer types. There is only potential profit if
1620 // the element type t is lower than _type; that is, for int types, if _type is
1621 // more restrictive than t. This only happens here if one is short and the other
1622 // char (both 16 bits), and in those cases we've made an intentional decision
1623 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1624 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1625 //
1626 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1627 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1628 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1629 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1630 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1631 // In fact, that could have been the original type of p1, and p1 could have
1632 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1633 // expression (LShiftL quux 3) independently optimized to the constant 8.
1634 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1635 && (_type->isa_vect() == NULL)
1636 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1637 // t might actually be lower than _type, if _type is a unique
1638 // concrete subclass of abstract class t.
1639 if (off_beyond_header) { // is the offset beyond the header?
1640 const Type* jt = t->join_speculative(_type);
1641 // In any case, do not allow the join, per se, to empty out the type.
1642 if (jt->empty() && !t->empty()) {
1643 // This can happen if a interface-typed array narrows to a class type.
1644 jt = _type;
1645 }
1646 #ifdef ASSERT
1647 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
1648 // The pointers in the autobox arrays are always non-null
1649 Node* base = adr->in(AddPNode::Base);
1650 if ((base != NULL) && base->is_DecodeN()) {
1651 // Get LoadN node which loads IntegerCache.cache field
1652 base = base->in(1);
1653 }
1654 if ((base != NULL) && base->is_Con()) {
1655 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
1656 if ((base_type != NULL) && base_type->is_autobox_cache()) {
1657 // It could be narrow oop
1658 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
1659 }
1660 }
1661 }
1662 #endif
1663 return jt;
1664 }
1665 }
1666 } else if (tp->base() == Type::InstPtr) {
1667 ciEnv* env = C->env();
1668 const TypeInstPtr* tinst = tp->is_instptr();
1669 ciKlass* klass = tinst->klass();
1670 assert( off != Type::OffsetBot ||
1671 // arrays can be cast to Objects
1672 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1673 // unsafe field access may not have a constant offset
1674 C->has_unsafe_access(),
1675 "Field accesses must be precise" );
1676 // For oop loads, we expect the _type to be precise
1677 if (klass == env->String_klass() &&
1678 adr->is_AddP() && off != Type::OffsetBot) {
1679 // For constant Strings treat the final fields as compile time constants.
1680 Node* base = adr->in(AddPNode::Base);
1681 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1682 if (t != NULL && t->singleton()) {
1683 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1684 if (field != NULL && field->is_final()) {
1685 ciObject* string = t->const_oop();
1686 ciConstant constant = string->as_instance()->field_value(field);
1687 if (constant.basic_type() == T_INT) {
1688 return TypeInt::make(constant.as_int());
1689 } else if (constant.basic_type() == T_ARRAY) {
1690 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1691 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1692 } else {
1693 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1694 }
1695 }
1696 }
1697 }
1698 }
1699 // Optimizations for constant objects
1700 ciObject* const_oop = tinst->const_oop();
1701 if (const_oop != NULL) {
1702 // For constant Boxed value treat the target field as a compile time constant.
1703 if (tinst->is_ptr_to_boxed_value()) {
1704 return tinst->get_const_boxed_value();
1705 } else
1706 // For constant CallSites treat the target field as a compile time constant.
1707 if (const_oop->is_call_site()) {
1708 ciCallSite* call_site = const_oop->as_call_site();
1709 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1710 if (field != NULL && field->is_call_site_target()) {
1711 ciMethodHandle* target = call_site->get_target();
1712 if (target != NULL) { // just in case
1713 ciConstant constant(T_OBJECT, target);
1714 const Type* t;
1715 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1716 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1717 } else {
1718 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1719 }
1720 // Add a dependence for invalidation of the optimization.
1721 if (!call_site->is_constant_call_site()) {
1722 C->dependencies()->assert_call_site_target_value(call_site, target);
1723 }
1724 return t;
1725 }
1726 }
1727 }
1728 }
1729 } else if (tp->base() == Type::KlassPtr) {
1730 assert( off != Type::OffsetBot ||
1731 // arrays can be cast to Objects
1732 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1733 // also allow array-loading from the primary supertype
1734 // array during subtype checks
1735 Opcode() == Op_LoadKlass,
1736 "Field accesses must be precise" );
1737 // For klass/static loads, we expect the _type to be precise
1738 }
1739
1740 const TypeKlassPtr *tkls = tp->isa_klassptr();
1741 if (tkls != NULL && !StressReflectiveCode) {
1742 ciKlass* klass = tkls->klass();
1743 if (klass->is_loaded() && tkls->klass_is_exact()) {
1744 // We are loading a field from a Klass metaobject whose identity
1745 // is known at compile time (the type is "exact" or "precise").
1746 // Check for fields we know are maintained as constants by the VM.
1747 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1748 // The field is Klass::_super_check_offset. Return its (constant) value.
1749 // (Folds up type checking code.)
1750 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1751 return TypeInt::make(klass->super_check_offset());
1752 }
1753 // Compute index into primary_supers array
1754 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1755 // Check for overflowing; use unsigned compare to handle the negative case.
1756 if( depth < ciKlass::primary_super_limit() ) {
1757 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1758 // (Folds up type checking code.)
1759 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1760 ciKlass *ss = klass->super_of_depth(depth);
1761 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1762 }
1763 const Type* aift = load_array_final_field(tkls, klass);
1764 if (aift != NULL) return aift;
1765 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1766 // The field is Klass::_java_mirror. Return its (constant) value.
1767 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1768 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1769 return TypeInstPtr::make(klass->java_mirror());
1770 }
1771 }
1772
1773 // We can still check if we are loading from the primary_supers array at a
1774 // shallow enough depth. Even though the klass is not exact, entries less
1775 // than or equal to its super depth are correct.
1776 if (klass->is_loaded() ) {
1777 ciType *inner = klass;
1778 while( inner->is_obj_array_klass() )
1779 inner = inner->as_obj_array_klass()->base_element_type();
1780 if( inner->is_instance_klass() &&
1781 !inner->as_instance_klass()->flags().is_interface() ) {
1782 // Compute index into primary_supers array
1783 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1784 // Check for overflowing; use unsigned compare to handle the negative case.
1785 if( depth < ciKlass::primary_super_limit() &&
1786 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1787 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1788 // (Folds up type checking code.)
1789 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1790 ciKlass *ss = klass->super_of_depth(depth);
1791 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1792 }
1793 }
1794 }
1795
1796 // If the type is enough to determine that the thing is not an array,
1797 // we can give the layout_helper a positive interval type.
1798 // This will help short-circuit some reflective code.
1799 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1800 && !klass->is_array_klass() // not directly typed as an array
1801 && !klass->is_interface() // specifically not Serializable & Cloneable
1802 && !klass->is_java_lang_Object() // not the supertype of all T[]
1803 ) {
1804 // Note: When interfaces are reliable, we can narrow the interface
1805 // test to (klass != Serializable && klass != Cloneable).
1806 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1807 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1808 // The key property of this type is that it folds up tests
1809 // for array-ness, since it proves that the layout_helper is positive.
1810 // Thus, a generic value like the basic object layout helper works fine.
1811 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1812 }
1813 }
1814
1815 // If we are loading from a freshly-allocated object, produce a zero,
1816 // if the load is provably beyond the header of the object.
1817 // (Also allow a variable load from a fresh array to produce zero.)
1818 const TypeOopPtr *tinst = tp->isa_oopptr();
1819 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1820 bool is_boxed_value = (tinst != NULL) && tinst->is_ptr_to_boxed_value();
1821 if (ReduceFieldZeroing || is_instance || is_boxed_value) {
1822 Node* value = can_see_stored_value(mem,phase);
1823 if (value != NULL && value->is_Con()) {
1824 assert(value->bottom_type()->higher_equal(_type),"sanity");
1825 return value->bottom_type();
1826 }
1827 }
1828
1829 if (is_instance) {
1830 // If we have an instance type and our memory input is the
1831 // programs's initial memory state, there is no matching store,
1832 // so just return a zero of the appropriate type
1833 Node *mem = in(MemNode::Memory);
1834 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1835 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1836 return Type::get_zero_type(_type->basic_type());
1837 }
1838 }
1839 return _type;
1840 }
1841
1842 //------------------------------match_edge-------------------------------------
1843 // Do we Match on this edge index or not? Match only the address.
1844 uint LoadNode::match_edge(uint idx) const {
1845 return idx == MemNode::Address;
1846 }
1847
1848 //--------------------------LoadBNode::Ideal--------------------------------------
1849 //
1850 // If the previous store is to the same address as this load,
1851 // and the value stored was larger than a byte, replace this load
1852 // with the value stored truncated to a byte. If no truncation is
1853 // needed, the replacement is done in LoadNode::Identity().
1854 //
1855 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1856 Node* mem = in(MemNode::Memory);
1857 Node* value = can_see_stored_value(mem,phase);
1858 if( value && !phase->type(value)->higher_equal( _type ) ) {
1859 Node *result = phase->transform( new LShiftINode(value, phase->intcon(24)) );
1860 return new RShiftINode(result, phase->intcon(24));
1861 }
1862 // Identity call will handle the case where truncation is not needed.
1863 return LoadNode::Ideal(phase, can_reshape);
1864 }
1865
1866 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1867 Node* mem = in(MemNode::Memory);
1868 Node* value = can_see_stored_value(mem,phase);
1869 if (value != NULL && value->is_Con() &&
1870 !value->bottom_type()->higher_equal(_type)) {
1871 // If the input to the store does not fit with the load's result type,
1872 // it must be truncated. We can't delay until Ideal call since
1873 // a singleton Value is needed for split_thru_phi optimization.
1874 int con = value->get_int();
1875 return TypeInt::make((con << 24) >> 24);
1876 }
1877 return LoadNode::Value(phase);
1878 }
1879
1880 //--------------------------LoadUBNode::Ideal-------------------------------------
1881 //
1882 // If the previous store is to the same address as this load,
1883 // and the value stored was larger than a byte, replace this load
1884 // with the value stored truncated to a byte. If no truncation is
1885 // needed, the replacement is done in LoadNode::Identity().
1886 //
1887 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1888 Node* mem = in(MemNode::Memory);
1889 Node* value = can_see_stored_value(mem, phase);
1890 if (value && !phase->type(value)->higher_equal(_type))
1891 return new AndINode(value, phase->intcon(0xFF));
1892 // Identity call will handle the case where truncation is not needed.
1893 return LoadNode::Ideal(phase, can_reshape);
1894 }
1895
1896 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1897 Node* mem = in(MemNode::Memory);
1898 Node* value = can_see_stored_value(mem,phase);
1899 if (value != NULL && value->is_Con() &&
1900 !value->bottom_type()->higher_equal(_type)) {
1901 // If the input to the store does not fit with the load's result type,
1902 // it must be truncated. We can't delay until Ideal call since
1903 // a singleton Value is needed for split_thru_phi optimization.
1904 int con = value->get_int();
1905 return TypeInt::make(con & 0xFF);
1906 }
1907 return LoadNode::Value(phase);
1908 }
1909
1910 //--------------------------LoadUSNode::Ideal-------------------------------------
1911 //
1912 // If the previous store is to the same address as this load,
1913 // and the value stored was larger than a char, replace this load
1914 // with the value stored truncated to a char. If no truncation is
1915 // needed, the replacement is done in LoadNode::Identity().
1916 //
1917 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1918 Node* mem = in(MemNode::Memory);
1919 Node* value = can_see_stored_value(mem,phase);
1920 if( value && !phase->type(value)->higher_equal( _type ) )
1921 return new AndINode(value,phase->intcon(0xFFFF));
1922 // Identity call will handle the case where truncation is not needed.
1923 return LoadNode::Ideal(phase, can_reshape);
1924 }
1925
1926 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1927 Node* mem = in(MemNode::Memory);
1928 Node* value = can_see_stored_value(mem,phase);
1929 if (value != NULL && value->is_Con() &&
1930 !value->bottom_type()->higher_equal(_type)) {
1931 // If the input to the store does not fit with the load's result type,
1932 // it must be truncated. We can't delay until Ideal call since
1933 // a singleton Value is needed for split_thru_phi optimization.
1934 int con = value->get_int();
1935 return TypeInt::make(con & 0xFFFF);
1936 }
1937 return LoadNode::Value(phase);
1938 }
1939
1940 //--------------------------LoadSNode::Ideal--------------------------------------
1941 //
1942 // If the previous store is to the same address as this load,
1943 // and the value stored was larger than a short, replace this load
1944 // with the value stored truncated to a short. If no truncation is
1945 // needed, the replacement is done in LoadNode::Identity().
1946 //
1947 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1948 Node* mem = in(MemNode::Memory);
1949 Node* value = can_see_stored_value(mem,phase);
1950 if( value && !phase->type(value)->higher_equal( _type ) ) {
1951 Node *result = phase->transform( new LShiftINode(value, phase->intcon(16)) );
1952 return new RShiftINode(result, phase->intcon(16));
1953 }
1954 // Identity call will handle the case where truncation is not needed.
1955 return LoadNode::Ideal(phase, can_reshape);
1956 }
1957
1958 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1959 Node* mem = in(MemNode::Memory);
1960 Node* value = can_see_stored_value(mem,phase);
1961 if (value != NULL && value->is_Con() &&
1962 !value->bottom_type()->higher_equal(_type)) {
1963 // If the input to the store does not fit with the load's result type,
1964 // it must be truncated. We can't delay until Ideal call since
1965 // a singleton Value is needed for split_thru_phi optimization.
1966 int con = value->get_int();
1967 return TypeInt::make((con << 16) >> 16);
1968 }
1969 return LoadNode::Value(phase);
1970 }
1971
1972 //=============================================================================
1973 //----------------------------LoadKlassNode::make------------------------------
1974 // Polymorphic factory method:
1975 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
1976 // sanity check the alias category against the created node type
1977 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
1978 assert(adr_type != NULL, "expecting TypeKlassPtr");
1979 #ifdef _LP64
1980 if (adr_type->is_ptr_to_narrowklass()) {
1981 assert(UseCompressedClassPointers, "no compressed klasses");
1982 Node* load_klass = gvn.transform(new LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
1983 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
1984 }
1985 #endif
1986 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1987 return new LoadKlassNode(ctl, mem, adr, at, tk, MemNode::unordered);
1988 }
1989
1990 //------------------------------Value------------------------------------------
1991 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1992 return klass_value_common(phase);
1993 }
1994
1995 // In most cases, LoadKlassNode does not have the control input set. If the control
1996 // input is set, it must not be removed (by LoadNode::Ideal()).
1997 bool LoadKlassNode::can_remove_control() const {
1998 return false;
1999 }
2000
2001 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
2002 // Either input is TOP ==> the result is TOP
2003 const Type *t1 = phase->type( in(MemNode::Memory) );
2004 if (t1 == Type::TOP) return Type::TOP;
2005 Node *adr = in(MemNode::Address);
2006 const Type *t2 = phase->type( adr );
2007 if (t2 == Type::TOP) return Type::TOP;
2008 const TypePtr *tp = t2->is_ptr();
2009 if (TypePtr::above_centerline(tp->ptr()) ||
2010 tp->ptr() == TypePtr::Null) return Type::TOP;
2011
2012 // Return a more precise klass, if possible
2013 const TypeInstPtr *tinst = tp->isa_instptr();
2014 if (tinst != NULL) {
2015 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
2016 int offset = tinst->offset();
2017 if (ik == phase->C->env()->Class_klass()
2018 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2019 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2020 // We are loading a special hidden field from a Class mirror object,
2021 // the field which points to the VM's Klass metaobject.
2022 ciType* t = tinst->java_mirror_type();
2023 // java_mirror_type returns non-null for compile-time Class constants.
2024 if (t != NULL) {
2025 // constant oop => constant klass
2026 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2027 if (t->is_void()) {
2028 // We cannot create a void array. Since void is a primitive type return null
2029 // klass. Users of this result need to do a null check on the returned klass.
2030 return TypePtr::NULL_PTR;
2031 }
2032 return TypeKlassPtr::make(ciArrayKlass::make(t));
2033 }
2034 if (!t->is_klass()) {
2035 // a primitive Class (e.g., int.class) has NULL for a klass field
2036 return TypePtr::NULL_PTR;
2037 }
2038 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
2039 return TypeKlassPtr::make(t->as_klass());
2040 }
2041 // non-constant mirror, so we can't tell what's going on
2042 }
2043 if( !ik->is_loaded() )
2044 return _type; // Bail out if not loaded
2045 if (offset == oopDesc::klass_offset_in_bytes()) {
2046 if (tinst->klass_is_exact()) {
2047 return TypeKlassPtr::make(ik);
2048 }
2049 // See if we can become precise: no subklasses and no interface
2050 // (Note: We need to support verified interfaces.)
2051 if (!ik->is_interface() && !ik->has_subklass()) {
2052 //assert(!UseExactTypes, "this code should be useless with exact types");
2053 // Add a dependence; if any subclass added we need to recompile
2054 if (!ik->is_final()) {
2055 // %%% should use stronger assert_unique_concrete_subtype instead
2056 phase->C->dependencies()->assert_leaf_type(ik);
2057 }
2058 // Return precise klass
2059 return TypeKlassPtr::make(ik);
2060 }
2061
2062 // Return root of possible klass
2063 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
2064 }
2065 }
2066
2067 // Check for loading klass from an array
2068 const TypeAryPtr *tary = tp->isa_aryptr();
2069 if( tary != NULL ) {
2070 ciKlass *tary_klass = tary->klass();
2071 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
2072 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
2073 if (tary->klass_is_exact()) {
2074 return TypeKlassPtr::make(tary_klass);
2075 }
2076 ciArrayKlass *ak = tary->klass()->as_array_klass();
2077 // If the klass is an object array, we defer the question to the
2078 // array component klass.
2079 if( ak->is_obj_array_klass() ) {
2080 assert( ak->is_loaded(), "" );
2081 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
2082 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
2083 ciInstanceKlass* ik = base_k->as_instance_klass();
2084 // See if we can become precise: no subklasses and no interface
2085 if (!ik->is_interface() && !ik->has_subklass()) {
2086 //assert(!UseExactTypes, "this code should be useless with exact types");
2087 // Add a dependence; if any subclass added we need to recompile
2088 if (!ik->is_final()) {
2089 phase->C->dependencies()->assert_leaf_type(ik);
2090 }
2091 // Return precise array klass
2092 return TypeKlassPtr::make(ak);
2093 }
2094 }
2095 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2096 } else { // Found a type-array?
2097 //assert(!UseExactTypes, "this code should be useless with exact types");
2098 assert( ak->is_type_array_klass(), "" );
2099 return TypeKlassPtr::make(ak); // These are always precise
2100 }
2101 }
2102 }
2103
2104 // Check for loading klass from an array klass
2105 const TypeKlassPtr *tkls = tp->isa_klassptr();
2106 if (tkls != NULL && !StressReflectiveCode) {
2107 ciKlass* klass = tkls->klass();
2108 if( !klass->is_loaded() )
2109 return _type; // Bail out if not loaded
2110 if( klass->is_obj_array_klass() &&
2111 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2112 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2113 // // Always returning precise element type is incorrect,
2114 // // e.g., element type could be object and array may contain strings
2115 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2116
2117 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2118 // according to the element type's subclassing.
2119 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2120 }
2121 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2122 tkls->offset() == in_bytes(Klass::super_offset())) {
2123 ciKlass* sup = klass->as_instance_klass()->super();
2124 // The field is Klass::_super. Return its (constant) value.
2125 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2126 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2127 }
2128 }
2129
2130 // Bailout case
2131 return LoadNode::Value(phase);
2132 }
2133
2134 //------------------------------Identity---------------------------------------
2135 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2136 // Also feed through the klass in Allocate(...klass...)._klass.
2137 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2138 return klass_identity_common(phase);
2139 }
2140
2141 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2142 Node* x = LoadNode::Identity(phase);
2143 if (x != this) return x;
2144
2145 // Take apart the address into an oop and and offset.
2146 // Return 'this' if we cannot.
2147 Node* adr = in(MemNode::Address);
2148 intptr_t offset = 0;
2149 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2150 if (base == NULL) return this;
2151 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2152 if (toop == NULL) return this;
2153
2154 // We can fetch the klass directly through an AllocateNode.
2155 // This works even if the klass is not constant (clone or newArray).
2156 if (offset == oopDesc::klass_offset_in_bytes()) {
2157 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2158 if (allocated_klass != NULL) {
2159 return allocated_klass;
2160 }
2161 }
2162
2163 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2164 // See inline_native_Class_query for occurrences of these patterns.
2165 // Java Example: x.getClass().isAssignableFrom(y)
2166 //
2167 // This improves reflective code, often making the Class
2168 // mirror go completely dead. (Current exception: Class
2169 // mirrors may appear in debug info, but we could clean them out by
2170 // introducing a new debug info operator for Klass*.java_mirror).
2171 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2172 && offset == java_lang_Class::klass_offset_in_bytes()) {
2173 // We are loading a special hidden field from a Class mirror,
2174 // the field which points to its Klass or ArrayKlass metaobject.
2175 if (base->is_Load()) {
2176 Node* adr2 = base->in(MemNode::Address);
2177 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2178 if (tkls != NULL && !tkls->empty()
2179 && (tkls->klass()->is_instance_klass() ||
2180 tkls->klass()->is_array_klass())
2181 && adr2->is_AddP()
2182 ) {
2183 int mirror_field = in_bytes(Klass::java_mirror_offset());
2184 if (tkls->offset() == mirror_field) {
2185 return adr2->in(AddPNode::Base);
2186 }
2187 }
2188 }
2189 }
2190
2191 return this;
2192 }
2193
2194
2195 //------------------------------Value------------------------------------------
2196 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2197 const Type *t = klass_value_common(phase);
2198 if (t == Type::TOP)
2199 return t;
2200
2201 return t->make_narrowklass();
2202 }
2203
2204 //------------------------------Identity---------------------------------------
2205 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2206 // Also feed through the klass in Allocate(...klass...)._klass.
2207 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2208 Node *x = klass_identity_common(phase);
2209
2210 const Type *t = phase->type( x );
2211 if( t == Type::TOP ) return x;
2212 if( t->isa_narrowklass()) return x;
2213 assert (!t->isa_narrowoop(), "no narrow oop here");
2214
2215 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2216 }
2217
2218 //------------------------------Value-----------------------------------------
2219 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2220 // Either input is TOP ==> the result is TOP
2221 const Type *t1 = phase->type( in(MemNode::Memory) );
2222 if( t1 == Type::TOP ) return Type::TOP;
2223 Node *adr = in(MemNode::Address);
2224 const Type *t2 = phase->type( adr );
2225 if( t2 == Type::TOP ) return Type::TOP;
2226 const TypePtr *tp = t2->is_ptr();
2227 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2228 const TypeAryPtr *tap = tp->isa_aryptr();
2229 if( !tap ) return _type;
2230 return tap->size();
2231 }
2232
2233 //-------------------------------Ideal---------------------------------------
2234 // Feed through the length in AllocateArray(...length...)._length.
2235 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2236 Node* p = MemNode::Ideal_common(phase, can_reshape);
2237 if (p) return (p == NodeSentinel) ? NULL : p;
2238
2239 // Take apart the address into an oop and and offset.
2240 // Return 'this' if we cannot.
2241 Node* adr = in(MemNode::Address);
2242 intptr_t offset = 0;
2243 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2244 if (base == NULL) return NULL;
2245 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2246 if (tary == NULL) return NULL;
2247
2248 // We can fetch the length directly through an AllocateArrayNode.
2249 // This works even if the length is not constant (clone or newArray).
2250 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2251 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2252 if (alloc != NULL) {
2253 Node* allocated_length = alloc->Ideal_length();
2254 Node* len = alloc->make_ideal_length(tary, phase);
2255 if (allocated_length != len) {
2256 // New CastII improves on this.
2257 return len;
2258 }
2259 }
2260 }
2261
2262 return NULL;
2263 }
2264
2265 //------------------------------Identity---------------------------------------
2266 // Feed through the length in AllocateArray(...length...)._length.
2267 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2268 Node* x = LoadINode::Identity(phase);
2269 if (x != this) return x;
2270
2271 // Take apart the address into an oop and and offset.
2272 // Return 'this' if we cannot.
2273 Node* adr = in(MemNode::Address);
2274 intptr_t offset = 0;
2275 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2276 if (base == NULL) return this;
2277 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2278 if (tary == NULL) return this;
2279
2280 // We can fetch the length directly through an AllocateArrayNode.
2281 // This works even if the length is not constant (clone or newArray).
2282 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2283 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2284 if (alloc != NULL) {
2285 Node* allocated_length = alloc->Ideal_length();
2286 // Do not allow make_ideal_length to allocate a CastII node.
2287 Node* len = alloc->make_ideal_length(tary, phase, false);
2288 if (allocated_length == len) {
2289 // Return allocated_length only if it would not be improved by a CastII.
2290 return allocated_length;
2291 }
2292 }
2293 }
2294
2295 return this;
2296
2297 }
2298
2299 //=============================================================================
2300 //---------------------------StoreNode::make-----------------------------------
2301 // Polymorphic factory method:
2302 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo) {
2303 assert((mo == unordered || mo == release), "unexpected");
2304 Compile* C = gvn.C;
2305 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2306 ctl != NULL, "raw memory operations should have control edge");
2307
2308 switch (bt) {
2309 case T_BOOLEAN:
2310 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2311 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2312 case T_CHAR:
2313 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2314 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo);
2315 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2316 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo);
2317 case T_METADATA:
2318 case T_ADDRESS:
2319 case T_OBJECT:
2320 #ifdef _LP64
2321 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2322 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2323 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2324 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2325 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2326 adr->bottom_type()->isa_rawptr())) {
2327 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2328 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2329 }
2330 #endif
2331 {
2332 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2333 }
2334 }
2335 ShouldNotReachHere();
2336 return (StoreNode*)NULL;
2337 }
2338
2339 StoreLNode* StoreLNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2340 bool require_atomic = true;
2341 return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2342 }
2343
2344 StoreDNode* StoreDNode::make_atomic(Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, MemOrd mo) {
2345 bool require_atomic = true;
2346 return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic);
2347 }
2348
2349
2350 //--------------------------bottom_type----------------------------------------
2351 const Type *StoreNode::bottom_type() const {
2352 return Type::MEMORY;
2353 }
2354
2355 //------------------------------hash-------------------------------------------
2356 uint StoreNode::hash() const {
2357 // unroll addition of interesting fields
2358 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2359
2360 // Since they are not commoned, do not hash them:
2361 return NO_HASH;
2362 }
2363
2364 //------------------------------Ideal------------------------------------------
2365 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2366 // When a store immediately follows a relevant allocation/initialization,
2367 // try to capture it into the initialization, or hoist it above.
2368 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2369 Node* p = MemNode::Ideal_common(phase, can_reshape);
2370 if (p) return (p == NodeSentinel) ? NULL : p;
2371
2372 Node* mem = in(MemNode::Memory);
2373 Node* address = in(MemNode::Address);
2374
2375 // Back-to-back stores to same address? Fold em up. Generally
2376 // unsafe if I have intervening uses... Also disallowed for StoreCM
2377 // since they must follow each StoreP operation. Redundant StoreCMs
2378 // are eliminated just before matching in final_graph_reshape.
2379 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2380 mem->Opcode() != Op_StoreCM) {
2381 // Looking at a dead closed cycle of memory?
2382 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2383
2384 assert(Opcode() == mem->Opcode() ||
2385 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2386 "no mismatched stores, except on raw memory");
2387
2388 if (mem->outcnt() == 1 && // check for intervening uses
2389 mem->as_Store()->memory_size() <= this->memory_size()) {
2390 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2391 // For example, 'mem' might be the final state at a conditional return.
2392 // Or, 'mem' might be used by some node which is live at the same time
2393 // 'this' is live, which might be unschedulable. So, require exactly
2394 // ONE user, the 'this' store, until such time as we clone 'mem' for
2395 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2396 if (can_reshape) { // (%%% is this an anachronism?)
2397 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2398 phase->is_IterGVN());
2399 } else {
2400 // It's OK to do this in the parser, since DU info is always accurate,
2401 // and the parser always refers to nodes via SafePointNode maps.
2402 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2403 }
2404 return this;
2405 }
2406 }
2407
2408 // Capture an unaliased, unconditional, simple store into an initializer.
2409 // Or, if it is independent of the allocation, hoist it above the allocation.
2410 if (ReduceFieldZeroing && /*can_reshape &&*/
2411 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2412 InitializeNode* init = mem->in(0)->as_Initialize();
2413 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
2414 if (offset > 0) {
2415 Node* moved = init->capture_store(this, offset, phase, can_reshape);
2416 // If the InitializeNode captured me, it made a raw copy of me,
2417 // and I need to disappear.
2418 if (moved != NULL) {
2419 // %%% hack to ensure that Ideal returns a new node:
2420 mem = MergeMemNode::make(mem);
2421 return mem; // fold me away
2422 }
2423 }
2424 }
2425
2426 return NULL; // No further progress
2427 }
2428
2429 //------------------------------Value-----------------------------------------
2430 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2431 // Either input is TOP ==> the result is TOP
2432 const Type *t1 = phase->type( in(MemNode::Memory) );
2433 if( t1 == Type::TOP ) return Type::TOP;
2434 const Type *t2 = phase->type( in(MemNode::Address) );
2435 if( t2 == Type::TOP ) return Type::TOP;
2436 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2437 if( t3 == Type::TOP ) return Type::TOP;
2438 return Type::MEMORY;
2439 }
2440
2441 //------------------------------Identity---------------------------------------
2442 // Remove redundant stores:
2443 // Store(m, p, Load(m, p)) changes to m.
2444 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2445 Node *StoreNode::Identity( PhaseTransform *phase ) {
2446 Node* mem = in(MemNode::Memory);
2447 Node* adr = in(MemNode::Address);
2448 Node* val = in(MemNode::ValueIn);
2449
2450 // Load then Store? Then the Store is useless
2451 if (val->is_Load() &&
2452 val->in(MemNode::Address)->eqv_uncast(adr) &&
2453 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2454 val->as_Load()->store_Opcode() == Opcode()) {
2455 return mem;
2456 }
2457
2458 // Two stores in a row of the same value?
2459 if (mem->is_Store() &&
2460 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2461 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2462 mem->Opcode() == Opcode()) {
2463 return mem;
2464 }
2465
2466 // Store of zero anywhere into a freshly-allocated object?
2467 // Then the store is useless.
2468 // (It must already have been captured by the InitializeNode.)
2469 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2470 // a newly allocated object is already all-zeroes everywhere
2471 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2472 return mem;
2473 }
2474
2475 // the store may also apply to zero-bits in an earlier object
2476 Node* prev_mem = find_previous_store(phase);
2477 // Steps (a), (b): Walk past independent stores to find an exact match.
2478 if (prev_mem != NULL) {
2479 Node* prev_val = can_see_stored_value(prev_mem, phase);
2480 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2481 // prev_val and val might differ by a cast; it would be good
2482 // to keep the more informative of the two.
2483 return mem;
2484 }
2485 }
2486 }
2487
2488 return this;
2489 }
2490
2491 //------------------------------match_edge-------------------------------------
2492 // Do we Match on this edge index or not? Match only memory & value
2493 uint StoreNode::match_edge(uint idx) const {
2494 return idx == MemNode::Address || idx == MemNode::ValueIn;
2495 }
2496
2497 //------------------------------cmp--------------------------------------------
2498 // Do not common stores up together. They generally have to be split
2499 // back up anyways, so do not bother.
2500 uint StoreNode::cmp( const Node &n ) const {
2501 return (&n == this); // Always fail except on self
2502 }
2503
2504 //------------------------------Ideal_masked_input-----------------------------
2505 // Check for a useless mask before a partial-word store
2506 // (StoreB ... (AndI valIn conIa) )
2507 // If (conIa & mask == mask) this simplifies to
2508 // (StoreB ... (valIn) )
2509 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2510 Node *val = in(MemNode::ValueIn);
2511 if( val->Opcode() == Op_AndI ) {
2512 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2513 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2514 set_req(MemNode::ValueIn, val->in(1));
2515 return this;
2516 }
2517 }
2518 return NULL;
2519 }
2520
2521
2522 //------------------------------Ideal_sign_extended_input----------------------
2523 // Check for useless sign-extension before a partial-word store
2524 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2525 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2526 // (StoreB ... (valIn) )
2527 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2528 Node *val = in(MemNode::ValueIn);
2529 if( val->Opcode() == Op_RShiftI ) {
2530 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2531 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2532 Node *shl = val->in(1);
2533 if( shl->Opcode() == Op_LShiftI ) {
2534 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2535 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2536 set_req(MemNode::ValueIn, shl->in(1));
2537 return this;
2538 }
2539 }
2540 }
2541 }
2542 return NULL;
2543 }
2544
2545 //------------------------------value_never_loaded-----------------------------------
2546 // Determine whether there are any possible loads of the value stored.
2547 // For simplicity, we actually check if there are any loads from the
2548 // address stored to, not just for loads of the value stored by this node.
2549 //
2550 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2551 Node *adr = in(Address);
2552 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2553 if (adr_oop == NULL)
2554 return false;
2555 if (!adr_oop->is_known_instance_field())
2556 return false; // if not a distinct instance, there may be aliases of the address
2557 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2558 Node *use = adr->fast_out(i);
2559 if (use->is_Load() || use->is_LoadStore()) {
2560 return false;
2561 }
2562 }
2563 return true;
2564 }
2565
2566 //=============================================================================
2567 //------------------------------Ideal------------------------------------------
2568 // If the store is from an AND mask that leaves the low bits untouched, then
2569 // we can skip the AND operation. If the store is from a sign-extension
2570 // (a left shift, then right shift) we can skip both.
2571 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2572 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2573 if( progress != NULL ) return progress;
2574
2575 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2576 if( progress != NULL ) return progress;
2577
2578 // Finally check the default case
2579 return StoreNode::Ideal(phase, can_reshape);
2580 }
2581
2582 //=============================================================================
2583 //------------------------------Ideal------------------------------------------
2584 // If the store is from an AND mask that leaves the low bits untouched, then
2585 // we can skip the AND operation
2586 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2587 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2588 if( progress != NULL ) return progress;
2589
2590 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2591 if( progress != NULL ) return progress;
2592
2593 // Finally check the default case
2594 return StoreNode::Ideal(phase, can_reshape);
2595 }
2596
2597 //=============================================================================
2598 //------------------------------Identity---------------------------------------
2599 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2600 // No need to card mark when storing a null ptr
2601 Node* my_store = in(MemNode::OopStore);
2602 if (my_store->is_Store()) {
2603 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2604 if( t1 == TypePtr::NULL_PTR ) {
2605 return in(MemNode::Memory);
2606 }
2607 }
2608 return this;
2609 }
2610
2611 //=============================================================================
2612 //------------------------------Ideal---------------------------------------
2613 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2614 Node* progress = StoreNode::Ideal(phase, can_reshape);
2615 if (progress != NULL) return progress;
2616
2617 Node* my_store = in(MemNode::OopStore);
2618 if (my_store->is_MergeMem()) {
2619 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2620 set_req(MemNode::OopStore, mem);
2621 return this;
2622 }
2623
2624 return NULL;
2625 }
2626
2627 //------------------------------Value-----------------------------------------
2628 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2629 // Either input is TOP ==> the result is TOP
2630 const Type *t = phase->type( in(MemNode::Memory) );
2631 if( t == Type::TOP ) return Type::TOP;
2632 t = phase->type( in(MemNode::Address) );
2633 if( t == Type::TOP ) return Type::TOP;
2634 t = phase->type( in(MemNode::ValueIn) );
2635 if( t == Type::TOP ) return Type::TOP;
2636 // If extra input is TOP ==> the result is TOP
2637 t = phase->type( in(MemNode::OopStore) );
2638 if( t == Type::TOP ) return Type::TOP;
2639
2640 return StoreNode::Value( phase );
2641 }
2642
2643
2644 //=============================================================================
2645 //----------------------------------SCMemProjNode------------------------------
2646 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2647 {
2648 return bottom_type();
2649 }
2650
2651 //=============================================================================
2652 //----------------------------------LoadStoreNode------------------------------
2653 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
2654 : Node(required),
2655 _type(rt),
2656 _adr_type(at)
2657 {
2658 init_req(MemNode::Control, c );
2659 init_req(MemNode::Memory , mem);
2660 init_req(MemNode::Address, adr);
2661 init_req(MemNode::ValueIn, val);
2662 init_class_id(Class_LoadStore);
2663 }
2664
2665 uint LoadStoreNode::ideal_reg() const {
2666 return _type->ideal_reg();
2667 }
2668
2669 bool LoadStoreNode::result_not_used() const {
2670 for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {
2671 Node *x = fast_out(i);
2672 if (x->Opcode() == Op_SCMemProj) continue;
2673 return false;
2674 }
2675 return true;
2676 }
2677
2678 uint LoadStoreNode::size_of() const { return sizeof(*this); }
2679
2680 //=============================================================================
2681 //----------------------------------LoadStoreConditionalNode--------------------
2682 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, NULL, TypeInt::BOOL, 5) {
2683 init_req(ExpectedIn, ex );
2684 }
2685
2686 //=============================================================================
2687 //-------------------------------adr_type--------------------------------------
2688 const TypePtr* ClearArrayNode::adr_type() const {
2689 Node *adr = in(3);
2690 if (adr == NULL) return NULL; // node is dead
2691 return MemNode::calculate_adr_type(adr->bottom_type());
2692 }
2693
2694 //------------------------------match_edge-------------------------------------
2695 // Do we Match on this edge index or not? Do not match memory
2696 uint ClearArrayNode::match_edge(uint idx) const {
2697 return idx > 1;
2698 }
2699
2700 //------------------------------Identity---------------------------------------
2701 // Clearing a zero length array does nothing
2702 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2703 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2704 }
2705
2706 //------------------------------Idealize---------------------------------------
2707 // Clearing a short array is faster with stores
2708 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2709 const int unit = BytesPerLong;
2710 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2711 if (!t) return NULL;
2712 if (!t->is_con()) return NULL;
2713 intptr_t raw_count = t->get_con();
2714 intptr_t size = raw_count;
2715 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2716 // Clearing nothing uses the Identity call.
2717 // Negative clears are possible on dead ClearArrays
2718 // (see jck test stmt114.stmt11402.val).
2719 if (size <= 0 || size % unit != 0) return NULL;
2720 intptr_t count = size / unit;
2721 // Length too long; use fast hardware clear
2722 if (size > Matcher::init_array_short_size) return NULL;
2723 Node *mem = in(1);
2724 if( phase->type(mem)==Type::TOP ) return NULL;
2725 Node *adr = in(3);
2726 const Type* at = phase->type(adr);
2727 if( at==Type::TOP ) return NULL;
2728 const TypePtr* atp = at->isa_ptr();
2729 // adjust atp to be the correct array element address type
2730 if (atp == NULL) atp = TypePtr::BOTTOM;
2731 else atp = atp->add_offset(Type::OffsetBot);
2732 // Get base for derived pointer purposes
2733 if( adr->Opcode() != Op_AddP ) Unimplemented();
2734 Node *base = adr->in(1);
2735
2736 Node *zero = phase->makecon(TypeLong::ZERO);
2737 Node *off = phase->MakeConX(BytesPerLong);
2738 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2739 count--;
2740 while( count-- ) {
2741 mem = phase->transform(mem);
2742 adr = phase->transform(new AddPNode(base,adr,off));
2743 mem = new StoreLNode(in(0),mem,adr,atp,zero,MemNode::unordered,false);
2744 }
2745 return mem;
2746 }
2747
2748 //----------------------------step_through----------------------------------
2749 // Return allocation input memory edge if it is different instance
2750 // or itself if it is the one we are looking for.
2751 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2752 Node* n = *np;
2753 assert(n->is_ClearArray(), "sanity");
2754 intptr_t offset;
2755 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2756 // This method is called only before Allocate nodes are expanded
2757 // during macro nodes expansion. Before that ClearArray nodes are
2758 // only generated in PhaseMacroExpand::generate_arraycopy() (before
2759 // Allocate nodes are expanded) which follows allocations.
2760 assert(alloc != NULL, "should have allocation");
2761 if (alloc->_idx == instance_id) {
2762 // Can not bypass initialization of the instance we are looking for.
2763 return false;
2764 }
2765 // Otherwise skip it.
2766 InitializeNode* init = alloc->initialization();
2767 if (init != NULL)
2768 *np = init->in(TypeFunc::Memory);
2769 else
2770 *np = alloc->in(TypeFunc::Memory);
2771 return true;
2772 }
2773
2774 //----------------------------clear_memory-------------------------------------
2775 // Generate code to initialize object storage to zero.
2776 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2777 intptr_t start_offset,
2778 Node* end_offset,
2779 PhaseGVN* phase) {
2780 intptr_t offset = start_offset;
2781
2782 int unit = BytesPerLong;
2783 if ((offset % unit) != 0) {
2784 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
2785 adr = phase->transform(adr);
2786 const TypePtr* atp = TypeRawPtr::BOTTOM;
2787 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2788 mem = phase->transform(mem);
2789 offset += BytesPerInt;
2790 }
2791 assert((offset % unit) == 0, "");
2792
2793 // Initialize the remaining stuff, if any, with a ClearArray.
2794 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2795 }
2796
2797 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2798 Node* start_offset,
2799 Node* end_offset,
2800 PhaseGVN* phase) {
2801 if (start_offset == end_offset) {
2802 // nothing to do
2803 return mem;
2804 }
2805
2806 int unit = BytesPerLong;
2807 Node* zbase = start_offset;
2808 Node* zend = end_offset;
2809
2810 // Scale to the unit required by the CPU:
2811 if (!Matcher::init_array_count_is_in_bytes) {
2812 Node* shift = phase->intcon(exact_log2(unit));
2813 zbase = phase->transform(new URShiftXNode(zbase, shift) );
2814 zend = phase->transform(new URShiftXNode(zend, shift) );
2815 }
2816
2817 // Bulk clear double-words
2818 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
2819 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
2820 mem = new ClearArrayNode(ctl, mem, zsize, adr);
2821 return phase->transform(mem);
2822 }
2823
2824 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2825 intptr_t start_offset,
2826 intptr_t end_offset,
2827 PhaseGVN* phase) {
2828 if (start_offset == end_offset) {
2829 // nothing to do
2830 return mem;
2831 }
2832
2833 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2834 intptr_t done_offset = end_offset;
2835 if ((done_offset % BytesPerLong) != 0) {
2836 done_offset -= BytesPerInt;
2837 }
2838 if (done_offset > start_offset) {
2839 mem = clear_memory(ctl, mem, dest,
2840 start_offset, phase->MakeConX(done_offset), phase);
2841 }
2842 if (done_offset < end_offset) { // emit the final 32-bit store
2843 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
2844 adr = phase->transform(adr);
2845 const TypePtr* atp = TypeRawPtr::BOTTOM;
2846 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
2847 mem = phase->transform(mem);
2848 done_offset += BytesPerInt;
2849 }
2850 assert(done_offset == end_offset, "");
2851 return mem;
2852 }
2853
2854 //=============================================================================
2855 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2856 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2857 _adr_type(C->get_adr_type(alias_idx))
2858 {
2859 init_class_id(Class_MemBar);
2860 Node* top = C->top();
2861 init_req(TypeFunc::I_O,top);
2862 init_req(TypeFunc::FramePtr,top);
2863 init_req(TypeFunc::ReturnAdr,top);
2864 if (precedent != NULL)
2865 init_req(TypeFunc::Parms, precedent);
2866 }
2867
2868 //------------------------------cmp--------------------------------------------
2869 uint MemBarNode::hash() const { return NO_HASH; }
2870 uint MemBarNode::cmp( const Node &n ) const {
2871 return (&n == this); // Always fail except on self
2872 }
2873
2874 //------------------------------make-------------------------------------------
2875 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2876 switch (opcode) {
2877 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
2878 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
2879 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
2880 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
2881 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
2882 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
2883 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
2884 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
2885 case Op_Initialize: return new InitializeNode(C, atp, pn);
2886 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
2887 default: ShouldNotReachHere(); return NULL;
2888 }
2889 }
2890
2891 //------------------------------Ideal------------------------------------------
2892 // Return a node which is more "ideal" than the current node. Strip out
2893 // control copies
2894 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2895 if (remove_dead_region(phase, can_reshape)) return this;
2896 // Don't bother trying to transform a dead node
2897 if (in(0) && in(0)->is_top()) {
2898 return NULL;
2899 }
2900
2901 bool progress = false;
2902 // Eliminate volatile MemBars for scalar replaced objects.
2903 if (can_reshape && req() == (Precedent+1)) {
2904 bool eliminate = false;
2905 int opc = Opcode();
2906 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
2907 // Volatile field loads and stores.
2908 Node* my_mem = in(MemBarNode::Precedent);
2909 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
2910 if ((my_mem != NULL) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
2911 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
2912 // replace this Precedent (decodeN) with the Load instead.
2913 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
2914 Node* load_node = my_mem->in(1);
2915 set_req(MemBarNode::Precedent, load_node);
2916 phase->is_IterGVN()->_worklist.push(my_mem);
2917 my_mem = load_node;
2918 } else {
2919 assert(my_mem->unique_out() == this, "sanity");
2920 del_req(Precedent);
2921 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
2922 my_mem = NULL;
2923 }
2924 progress = true;
2925 }
2926 if (my_mem != NULL && my_mem->is_Mem()) {
2927 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2928 // Check for scalar replaced object reference.
2929 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2930 t_oop->offset() != Type::OffsetBot &&
2931 t_oop->offset() != Type::OffsetTop) {
2932 eliminate = true;
2933 }
2934 }
2935 } else if (opc == Op_MemBarRelease) {
2936 // Final field stores.
2937 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent), phase);
2938 if ((alloc != NULL) && alloc->is_Allocate() &&
2939 alloc->as_Allocate()->_is_non_escaping) {
2940 // The allocated object does not escape.
2941 eliminate = true;
2942 }
2943 }
2944 if (eliminate) {
2945 // Replace MemBar projections by its inputs.
2946 PhaseIterGVN* igvn = phase->is_IterGVN();
2947 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2948 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2949 // Must return either the original node (now dead) or a new node
2950 // (Do not return a top here, since that would break the uniqueness of top.)
2951 return new ConINode(TypeInt::ZERO);
2952 }
2953 }
2954 return progress ? this : NULL;
2955 }
2956
2957 //------------------------------Value------------------------------------------
2958 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2959 if( !in(0) ) return Type::TOP;
2960 if( phase->type(in(0)) == Type::TOP )
2961 return Type::TOP;
2962 return TypeTuple::MEMBAR;
2963 }
2964
2965 //------------------------------match------------------------------------------
2966 // Construct projections for memory.
2967 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2968 switch (proj->_con) {
2969 case TypeFunc::Control:
2970 case TypeFunc::Memory:
2971 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2972 }
2973 ShouldNotReachHere();
2974 return NULL;
2975 }
2976
2977 //===========================InitializeNode====================================
2978 // SUMMARY:
2979 // This node acts as a memory barrier on raw memory, after some raw stores.
2980 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2981 // The Initialize can 'capture' suitably constrained stores as raw inits.
2982 // It can coalesce related raw stores into larger units (called 'tiles').
2983 // It can avoid zeroing new storage for memory units which have raw inits.
2984 // At macro-expansion, it is marked 'complete', and does not optimize further.
2985 //
2986 // EXAMPLE:
2987 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2988 // ctl = incoming control; mem* = incoming memory
2989 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2990 // First allocate uninitialized memory and fill in the header:
2991 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2992 // ctl := alloc.Control; mem* := alloc.Memory*
2993 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2994 // Then initialize to zero the non-header parts of the raw memory block:
2995 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2996 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2997 // After the initialize node executes, the object is ready for service:
2998 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2999 // Suppose its body is immediately initialized as {1,2}:
3000 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3001 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3002 // mem.SLICE(#short[*]) := store2
3003 //
3004 // DETAILS:
3005 // An InitializeNode collects and isolates object initialization after
3006 // an AllocateNode and before the next possible safepoint. As a
3007 // memory barrier (MemBarNode), it keeps critical stores from drifting
3008 // down past any safepoint or any publication of the allocation.
3009 // Before this barrier, a newly-allocated object may have uninitialized bits.
3010 // After this barrier, it may be treated as a real oop, and GC is allowed.
3011 //
3012 // The semantics of the InitializeNode include an implicit zeroing of
3013 // the new object from object header to the end of the object.
3014 // (The object header and end are determined by the AllocateNode.)
3015 //
3016 // Certain stores may be added as direct inputs to the InitializeNode.
3017 // These stores must update raw memory, and they must be to addresses
3018 // derived from the raw address produced by AllocateNode, and with
3019 // a constant offset. They must be ordered by increasing offset.
3020 // The first one is at in(RawStores), the last at in(req()-1).
3021 // Unlike most memory operations, they are not linked in a chain,
3022 // but are displayed in parallel as users of the rawmem output of
3023 // the allocation.
3024 //
3025 // (See comments in InitializeNode::capture_store, which continue
3026 // the example given above.)
3027 //
3028 // When the associated Allocate is macro-expanded, the InitializeNode
3029 // may be rewritten to optimize collected stores. A ClearArrayNode
3030 // may also be created at that point to represent any required zeroing.
3031 // The InitializeNode is then marked 'complete', prohibiting further
3032 // capturing of nearby memory operations.
3033 //
3034 // During macro-expansion, all captured initializations which store
3035 // constant values of 32 bits or smaller are coalesced (if advantageous)
3036 // into larger 'tiles' 32 or 64 bits. This allows an object to be
3037 // initialized in fewer memory operations. Memory words which are
3038 // covered by neither tiles nor non-constant stores are pre-zeroed
3039 // by explicit stores of zero. (The code shape happens to do all
3040 // zeroing first, then all other stores, with both sequences occurring
3041 // in order of ascending offsets.)
3042 //
3043 // Alternatively, code may be inserted between an AllocateNode and its
3044 // InitializeNode, to perform arbitrary initialization of the new object.
3045 // E.g., the object copying intrinsics insert complex data transfers here.
3046 // The initialization must then be marked as 'complete' disable the
3047 // built-in zeroing semantics and the collection of initializing stores.
3048 //
3049 // While an InitializeNode is incomplete, reads from the memory state
3050 // produced by it are optimizable if they match the control edge and
3051 // new oop address associated with the allocation/initialization.
3052 // They return a stored value (if the offset matches) or else zero.
3053 // A write to the memory state, if it matches control and address,
3054 // and if it is to a constant offset, may be 'captured' by the
3055 // InitializeNode. It is cloned as a raw memory operation and rewired
3056 // inside the initialization, to the raw oop produced by the allocation.
3057 // Operations on addresses which are provably distinct (e.g., to
3058 // other AllocateNodes) are allowed to bypass the initialization.
3059 //
3060 // The effect of all this is to consolidate object initialization
3061 // (both arrays and non-arrays, both piecewise and bulk) into a
3062 // single location, where it can be optimized as a unit.
3063 //
3064 // Only stores with an offset less than TrackedInitializationLimit words
3065 // will be considered for capture by an InitializeNode. This puts a
3066 // reasonable limit on the complexity of optimized initializations.
3067
3068 //---------------------------InitializeNode------------------------------------
3069 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
3070 : _is_complete(Incomplete), _does_not_escape(false),
3071 MemBarNode(C, adr_type, rawoop)
3072 {
3073 init_class_id(Class_Initialize);
3074
3075 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
3076 assert(in(RawAddress) == rawoop, "proper init");
3077 // Note: allocation() can be NULL, for secondary initialization barriers
3078 }
3079
3080 // Since this node is not matched, it will be processed by the
3081 // register allocator. Declare that there are no constraints
3082 // on the allocation of the RawAddress edge.
3083 const RegMask &InitializeNode::in_RegMask(uint idx) const {
3084 // This edge should be set to top, by the set_complete. But be conservative.
3085 if (idx == InitializeNode::RawAddress)
3086 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
3087 return RegMask::Empty;
3088 }
3089
3090 Node* InitializeNode::memory(uint alias_idx) {
3091 Node* mem = in(Memory);
3092 if (mem->is_MergeMem()) {
3093 return mem->as_MergeMem()->memory_at(alias_idx);
3094 } else {
3095 // incoming raw memory is not split
3096 return mem;
3097 }
3098 }
3099
3100 bool InitializeNode::is_non_zero() {
3101 if (is_complete()) return false;
3102 remove_extra_zeroes();
3103 return (req() > RawStores);
3104 }
3105
3106 void InitializeNode::set_complete(PhaseGVN* phase) {
3107 assert(!is_complete(), "caller responsibility");
3108 _is_complete = Complete;
3109
3110 // After this node is complete, it contains a bunch of
3111 // raw-memory initializations. There is no need for
3112 // it to have anything to do with non-raw memory effects.
3113 // Therefore, tell all non-raw users to re-optimize themselves,
3114 // after skipping the memory effects of this initialization.
3115 PhaseIterGVN* igvn = phase->is_IterGVN();
3116 if (igvn) igvn->add_users_to_worklist(this);
3117 }
3118
3119 // convenience function
3120 // return false if the init contains any stores already
3121 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3122 InitializeNode* init = initialization();
3123 if (init == NULL || init->is_complete()) return false;
3124 init->remove_extra_zeroes();
3125 // for now, if this allocation has already collected any inits, bail:
3126 if (init->is_non_zero()) return false;
3127 init->set_complete(phase);
3128 return true;
3129 }
3130
3131 void InitializeNode::remove_extra_zeroes() {
3132 if (req() == RawStores) return;
3133 Node* zmem = zero_memory();
3134 uint fill = RawStores;
3135 for (uint i = fill; i < req(); i++) {
3136 Node* n = in(i);
3137 if (n->is_top() || n == zmem) continue; // skip
3138 if (fill < i) set_req(fill, n); // compact
3139 ++fill;
3140 }
3141 // delete any empty spaces created:
3142 while (fill < req()) {
3143 del_req(fill);
3144 }
3145 }
3146
3147 // Helper for remembering which stores go with which offsets.
3148 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3149 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3150 intptr_t offset = -1;
3151 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3152 phase, offset);
3153 if (base == NULL) return -1; // something is dead,
3154 if (offset < 0) return -1; // dead, dead
3155 return offset;
3156 }
3157
3158 // Helper for proving that an initialization expression is
3159 // "simple enough" to be folded into an object initialization.
3160 // Attempts to prove that a store's initial value 'n' can be captured
3161 // within the initialization without creating a vicious cycle, such as:
3162 // { Foo p = new Foo(); p.next = p; }
3163 // True for constants and parameters and small combinations thereof.
3164 bool InitializeNode::detect_init_independence(Node* n, int& count) {
3165 if (n == NULL) return true; // (can this really happen?)
3166 if (n->is_Proj()) n = n->in(0);
3167 if (n == this) return false; // found a cycle
3168 if (n->is_Con()) return true;
3169 if (n->is_Start()) return true; // params, etc., are OK
3170 if (n->is_Root()) return true; // even better
3171
3172 Node* ctl = n->in(0);
3173 if (ctl != NULL && !ctl->is_top()) {
3174 if (ctl->is_Proj()) ctl = ctl->in(0);
3175 if (ctl == this) return false;
3176
3177 // If we already know that the enclosing memory op is pinned right after
3178 // the init, then any control flow that the store has picked up
3179 // must have preceded the init, or else be equal to the init.
3180 // Even after loop optimizations (which might change control edges)
3181 // a store is never pinned *before* the availability of its inputs.
3182 if (!MemNode::all_controls_dominate(n, this))
3183 return false; // failed to prove a good control
3184 }
3185
3186 // Check data edges for possible dependencies on 'this'.
3187 if ((count += 1) > 20) return false; // complexity limit
3188 for (uint i = 1; i < n->req(); i++) {
3189 Node* m = n->in(i);
3190 if (m == NULL || m == n || m->is_top()) continue;
3191 uint first_i = n->find_edge(m);
3192 if (i != first_i) continue; // process duplicate edge just once
3193 if (!detect_init_independence(m, count)) {
3194 return false;
3195 }
3196 }
3197
3198 return true;
3199 }
3200
3201 // Here are all the checks a Store must pass before it can be moved into
3202 // an initialization. Returns zero if a check fails.
3203 // On success, returns the (constant) offset to which the store applies,
3204 // within the initialized memory.
3205 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase, bool can_reshape) {
3206 const int FAIL = 0;
3207 if (st->req() != MemNode::ValueIn + 1)
3208 return FAIL; // an inscrutable StoreNode (card mark?)
3209 Node* ctl = st->in(MemNode::Control);
3210 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3211 return FAIL; // must be unconditional after the initialization
3212 Node* mem = st->in(MemNode::Memory);
3213 if (!(mem->is_Proj() && mem->in(0) == this))
3214 return FAIL; // must not be preceded by other stores
3215 Node* adr = st->in(MemNode::Address);
3216 intptr_t offset;
3217 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3218 if (alloc == NULL)
3219 return FAIL; // inscrutable address
3220 if (alloc != allocation())
3221 return FAIL; // wrong allocation! (store needs to float up)
3222 Node* val = st->in(MemNode::ValueIn);
3223 int complexity_count = 0;
3224 if (!detect_init_independence(val, complexity_count))
3225 return FAIL; // stored value must be 'simple enough'
3226
3227 // The Store can be captured only if nothing after the allocation
3228 // and before the Store is using the memory location that the store
3229 // overwrites.
3230 bool failed = false;
3231 // If is_complete_with_arraycopy() is true the shape of the graph is
3232 // well defined and is safe so no need for extra checks.
3233 if (!is_complete_with_arraycopy()) {
3234 // We are going to look at each use of the memory state following
3235 // the allocation to make sure nothing reads the memory that the
3236 // Store writes.
3237 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
3238 int alias_idx = phase->C->get_alias_index(t_adr);
3239 ResourceMark rm;
3240 Unique_Node_List mems;
3241 mems.push(mem);
3242 Node* unique_merge = NULL;
3243 for (uint next = 0; next < mems.size(); ++next) {
3244 Node *m = mems.at(next);
3245 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3246 Node *n = m->fast_out(j);
3247 if (n->outcnt() == 0) {
3248 continue;
3249 }
3250 if (n == st) {
3251 continue;
3252 } else if (n->in(0) != NULL && n->in(0) != ctl) {
3253 // If the control of this use is different from the control
3254 // of the Store which is right after the InitializeNode then
3255 // this node cannot be between the InitializeNode and the
3256 // Store.
3257 continue;
3258 } else if (n->is_MergeMem()) {
3259 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
3260 // We can hit a MergeMemNode (that will likely go away
3261 // later) that is a direct use of the memory state
3262 // following the InitializeNode on the same slice as the
3263 // store node that we'd like to capture. We need to check
3264 // the uses of the MergeMemNode.
3265 mems.push(n);
3266 }
3267 } else if (n->is_Mem()) {
3268 Node* other_adr = n->in(MemNode::Address);
3269 if (other_adr == adr) {
3270 failed = true;
3271 break;
3272 } else {
3273 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
3274 if (other_t_adr != NULL) {
3275 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
3276 if (other_alias_idx == alias_idx) {
3277 // A load from the same memory slice as the store right
3278 // after the InitializeNode. We check the control of the
3279 // object/array that is loaded from. If it's the same as
3280 // the store control then we cannot capture the store.
3281 assert(!n->is_Store(), "2 stores to same slice on same control?");
3282 Node* base = other_adr;
3283 assert(base->is_AddP(), err_msg_res("should be addp but is %s", base->Name()));
3284 base = base->in(AddPNode::Base);
3285 if (base != NULL) {
3286 base = base->uncast();
3287 if (base->is_Proj() && base->in(0) == alloc) {
3288 failed = true;
3289 break;
3290 }
3291 }
3292 }
3293 }
3294 }
3295 } else {
3296 failed = true;
3297 break;
3298 }
3299 }
3300 }
3301 }
3302 if (failed) {
3303 if (!can_reshape) {
3304 // We decided we couldn't capture the store during parsing. We
3305 // should try again during the next IGVN once the graph is
3306 // cleaner.
3307 phase->C->record_for_igvn(st);
3308 }
3309 return FAIL;
3310 }
3311
3312 return offset; // success
3313 }
3314
3315 // Find the captured store in(i) which corresponds to the range
3316 // [start..start+size) in the initialized object.
3317 // If there is one, return its index i. If there isn't, return the
3318 // negative of the index where it should be inserted.
3319 // Return 0 if the queried range overlaps an initialization boundary
3320 // or if dead code is encountered.
3321 // If size_in_bytes is zero, do not bother with overlap checks.
3322 int InitializeNode::captured_store_insertion_point(intptr_t start,
3323 int size_in_bytes,
3324 PhaseTransform* phase) {
3325 const int FAIL = 0, MAX_STORE = BytesPerLong;
3326
3327 if (is_complete())
3328 return FAIL; // arraycopy got here first; punt
3329
3330 assert(allocation() != NULL, "must be present");
3331
3332 // no negatives, no header fields:
3333 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3334
3335 // after a certain size, we bail out on tracking all the stores:
3336 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3337 if (start >= ti_limit) return FAIL;
3338
3339 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3340 if (i >= limit) return -(int)i; // not found; here is where to put it
3341
3342 Node* st = in(i);
3343 intptr_t st_off = get_store_offset(st, phase);
3344 if (st_off < 0) {
3345 if (st != zero_memory()) {
3346 return FAIL; // bail out if there is dead garbage
3347 }
3348 } else if (st_off > start) {
3349 // ...we are done, since stores are ordered
3350 if (st_off < start + size_in_bytes) {
3351 return FAIL; // the next store overlaps
3352 }
3353 return -(int)i; // not found; here is where to put it
3354 } else if (st_off < start) {
3355 if (size_in_bytes != 0 &&
3356 start < st_off + MAX_STORE &&
3357 start < st_off + st->as_Store()->memory_size()) {
3358 return FAIL; // the previous store overlaps
3359 }
3360 } else {
3361 if (size_in_bytes != 0 &&
3362 st->as_Store()->memory_size() != size_in_bytes) {
3363 return FAIL; // mismatched store size
3364 }
3365 return i;
3366 }
3367
3368 ++i;
3369 }
3370 }
3371
3372 // Look for a captured store which initializes at the offset 'start'
3373 // with the given size. If there is no such store, and no other
3374 // initialization interferes, then return zero_memory (the memory
3375 // projection of the AllocateNode).
3376 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3377 PhaseTransform* phase) {
3378 assert(stores_are_sane(phase), "");
3379 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3380 if (i == 0) {
3381 return NULL; // something is dead
3382 } else if (i < 0) {
3383 return zero_memory(); // just primordial zero bits here
3384 } else {
3385 Node* st = in(i); // here is the store at this position
3386 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3387 return st;
3388 }
3389 }
3390
3391 // Create, as a raw pointer, an address within my new object at 'offset'.
3392 Node* InitializeNode::make_raw_address(intptr_t offset,
3393 PhaseTransform* phase) {
3394 Node* addr = in(RawAddress);
3395 if (offset != 0) {
3396 Compile* C = phase->C;
3397 addr = phase->transform( new AddPNode(C->top(), addr,
3398 phase->MakeConX(offset)) );
3399 }
3400 return addr;
3401 }
3402
3403 // Clone the given store, converting it into a raw store
3404 // initializing a field or element of my new object.
3405 // Caller is responsible for retiring the original store,
3406 // with subsume_node or the like.
3407 //
3408 // From the example above InitializeNode::InitializeNode,
3409 // here are the old stores to be captured:
3410 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3411 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3412 //
3413 // Here is the changed code; note the extra edges on init:
3414 // alloc = (Allocate ...)
3415 // rawoop = alloc.RawAddress
3416 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3417 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3418 // init = (Initialize alloc.Control alloc.Memory rawoop
3419 // rawstore1 rawstore2)
3420 //
3421 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3422 PhaseTransform* phase, bool can_reshape) {
3423 assert(stores_are_sane(phase), "");
3424
3425 if (start < 0) return NULL;
3426 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
3427
3428 Compile* C = phase->C;
3429 int size_in_bytes = st->memory_size();
3430 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3431 if (i == 0) return NULL; // bail out
3432 Node* prev_mem = NULL; // raw memory for the captured store
3433 if (i > 0) {
3434 prev_mem = in(i); // there is a pre-existing store under this one
3435 set_req(i, C->top()); // temporarily disconnect it
3436 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3437 } else {
3438 i = -i; // no pre-existing store
3439 prev_mem = zero_memory(); // a slice of the newly allocated object
3440 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3441 set_req(--i, C->top()); // reuse this edge; it has been folded away
3442 else
3443 ins_req(i, C->top()); // build a new edge
3444 }
3445 Node* new_st = st->clone();
3446 new_st->set_req(MemNode::Control, in(Control));
3447 new_st->set_req(MemNode::Memory, prev_mem);
3448 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3449 new_st = phase->transform(new_st);
3450
3451 // At this point, new_st might have swallowed a pre-existing store
3452 // at the same offset, or perhaps new_st might have disappeared,
3453 // if it redundantly stored the same value (or zero to fresh memory).
3454
3455 // In any case, wire it in:
3456 phase->igvn_rehash_node_delayed(this);
3457 set_req(i, new_st);
3458
3459 // The caller may now kill the old guy.
3460 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3461 assert(check_st == new_st || check_st == NULL, "must be findable");
3462 assert(!is_complete(), "");
3463 return new_st;
3464 }
3465
3466 static bool store_constant(jlong* tiles, int num_tiles,
3467 intptr_t st_off, int st_size,
3468 jlong con) {
3469 if ((st_off & (st_size-1)) != 0)
3470 return false; // strange store offset (assume size==2**N)
3471 address addr = (address)tiles + st_off;
3472 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3473 switch (st_size) {
3474 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3475 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3476 case sizeof(jint): *(jint*) addr = (jint) con; break;
3477 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3478 default: return false; // strange store size (detect size!=2**N here)
3479 }
3480 return true; // return success to caller
3481 }
3482
3483 // Coalesce subword constants into int constants and possibly
3484 // into long constants. The goal, if the CPU permits,
3485 // is to initialize the object with a small number of 64-bit tiles.
3486 // Also, convert floating-point constants to bit patterns.
3487 // Non-constants are not relevant to this pass.
3488 //
3489 // In terms of the running example on InitializeNode::InitializeNode
3490 // and InitializeNode::capture_store, here is the transformation
3491 // of rawstore1 and rawstore2 into rawstore12:
3492 // alloc = (Allocate ...)
3493 // rawoop = alloc.RawAddress
3494 // tile12 = 0x00010002
3495 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3496 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3497 //
3498 void
3499 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3500 Node* size_in_bytes,
3501 PhaseGVN* phase) {
3502 Compile* C = phase->C;
3503
3504 assert(stores_are_sane(phase), "");
3505 // Note: After this pass, they are not completely sane,
3506 // since there may be some overlaps.
3507
3508 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3509
3510 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3511 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3512 size_limit = MIN2(size_limit, ti_limit);
3513 size_limit = align_size_up(size_limit, BytesPerLong);
3514 int num_tiles = size_limit / BytesPerLong;
3515
3516 // allocate space for the tile map:
3517 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3518 jlong tiles_buf[small_len];
3519 Node* nodes_buf[small_len];
3520 jlong inits_buf[small_len];
3521 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3522 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3523 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3524 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3525 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3526 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3527 // tiles: exact bitwise model of all primitive constants
3528 // nodes: last constant-storing node subsumed into the tiles model
3529 // inits: which bytes (in each tile) are touched by any initializations
3530
3531 //// Pass A: Fill in the tile model with any relevant stores.
3532
3533 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3534 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3535 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3536 Node* zmem = zero_memory(); // initially zero memory state
3537 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3538 Node* st = in(i);
3539 intptr_t st_off = get_store_offset(st, phase);
3540
3541 // Figure out the store's offset and constant value:
3542 if (st_off < header_size) continue; //skip (ignore header)
3543 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3544 int st_size = st->as_Store()->memory_size();
3545 if (st_off + st_size > size_limit) break;
3546
3547 // Record which bytes are touched, whether by constant or not.
3548 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3549 continue; // skip (strange store size)
3550
3551 const Type* val = phase->type(st->in(MemNode::ValueIn));
3552 if (!val->singleton()) continue; //skip (non-con store)
3553 BasicType type = val->basic_type();
3554
3555 jlong con = 0;
3556 switch (type) {
3557 case T_INT: con = val->is_int()->get_con(); break;
3558 case T_LONG: con = val->is_long()->get_con(); break;
3559 case T_FLOAT: con = jint_cast(val->getf()); break;
3560 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3561 default: continue; //skip (odd store type)
3562 }
3563
3564 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3565 st->Opcode() == Op_StoreL) {
3566 continue; // This StoreL is already optimal.
3567 }
3568
3569 // Store down the constant.
3570 store_constant(tiles, num_tiles, st_off, st_size, con);
3571
3572 intptr_t j = st_off >> LogBytesPerLong;
3573
3574 if (type == T_INT && st_size == BytesPerInt
3575 && (st_off & BytesPerInt) == BytesPerInt) {
3576 jlong lcon = tiles[j];
3577 if (!Matcher::isSimpleConstant64(lcon) &&
3578 st->Opcode() == Op_StoreI) {
3579 // This StoreI is already optimal by itself.
3580 jint* intcon = (jint*) &tiles[j];
3581 intcon[1] = 0; // undo the store_constant()
3582
3583 // If the previous store is also optimal by itself, back up and
3584 // undo the action of the previous loop iteration... if we can.
3585 // But if we can't, just let the previous half take care of itself.
3586 st = nodes[j];
3587 st_off -= BytesPerInt;
3588 con = intcon[0];
3589 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3590 assert(st_off >= header_size, "still ignoring header");
3591 assert(get_store_offset(st, phase) == st_off, "must be");
3592 assert(in(i-1) == zmem, "must be");
3593 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3594 assert(con == tcon->is_int()->get_con(), "must be");
3595 // Undo the effects of the previous loop trip, which swallowed st:
3596 intcon[0] = 0; // undo store_constant()
3597 set_req(i-1, st); // undo set_req(i, zmem)
3598 nodes[j] = NULL; // undo nodes[j] = st
3599 --old_subword; // undo ++old_subword
3600 }
3601 continue; // This StoreI is already optimal.
3602 }
3603 }
3604
3605 // This store is not needed.
3606 set_req(i, zmem);
3607 nodes[j] = st; // record for the moment
3608 if (st_size < BytesPerLong) // something has changed
3609 ++old_subword; // includes int/float, but who's counting...
3610 else ++old_long;
3611 }
3612
3613 if ((old_subword + old_long) == 0)
3614 return; // nothing more to do
3615
3616 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3617 // Be sure to insert them before overlapping non-constant stores.
3618 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3619 for (int j = 0; j < num_tiles; j++) {
3620 jlong con = tiles[j];
3621 jlong init = inits[j];
3622 if (con == 0) continue;
3623 jint con0, con1; // split the constant, address-wise
3624 jint init0, init1; // split the init map, address-wise
3625 { union { jlong con; jint intcon[2]; } u;
3626 u.con = con;
3627 con0 = u.intcon[0];
3628 con1 = u.intcon[1];
3629 u.con = init;
3630 init0 = u.intcon[0];
3631 init1 = u.intcon[1];
3632 }
3633
3634 Node* old = nodes[j];
3635 assert(old != NULL, "need the prior store");
3636 intptr_t offset = (j * BytesPerLong);
3637
3638 bool split = !Matcher::isSimpleConstant64(con);
3639
3640 if (offset < header_size) {
3641 assert(offset + BytesPerInt >= header_size, "second int counts");
3642 assert(*(jint*)&tiles[j] == 0, "junk in header");
3643 split = true; // only the second word counts
3644 // Example: int a[] = { 42 ... }
3645 } else if (con0 == 0 && init0 == -1) {
3646 split = true; // first word is covered by full inits
3647 // Example: int a[] = { ... foo(), 42 ... }
3648 } else if (con1 == 0 && init1 == -1) {
3649 split = true; // second word is covered by full inits
3650 // Example: int a[] = { ... 42, foo() ... }
3651 }
3652
3653 // Here's a case where init0 is neither 0 nor -1:
3654 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3655 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3656 // In this case the tile is not split; it is (jlong)42.
3657 // The big tile is stored down, and then the foo() value is inserted.
3658 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3659
3660 Node* ctl = old->in(MemNode::Control);
3661 Node* adr = make_raw_address(offset, phase);
3662 const TypePtr* atp = TypeRawPtr::BOTTOM;
3663
3664 // One or two coalesced stores to plop down.
3665 Node* st[2];
3666 intptr_t off[2];
3667 int nst = 0;
3668 if (!split) {
3669 ++new_long;
3670 off[nst] = offset;
3671 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3672 phase->longcon(con), T_LONG, MemNode::unordered);
3673 } else {
3674 // Omit either if it is a zero.
3675 if (con0 != 0) {
3676 ++new_int;
3677 off[nst] = offset;
3678 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3679 phase->intcon(con0), T_INT, MemNode::unordered);
3680 }
3681 if (con1 != 0) {
3682 ++new_int;
3683 offset += BytesPerInt;
3684 adr = make_raw_address(offset, phase);
3685 off[nst] = offset;
3686 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3687 phase->intcon(con1), T_INT, MemNode::unordered);
3688 }
3689 }
3690
3691 // Insert second store first, then the first before the second.
3692 // Insert each one just before any overlapping non-constant stores.
3693 while (nst > 0) {
3694 Node* st1 = st[--nst];
3695 C->copy_node_notes_to(st1, old);
3696 st1 = phase->transform(st1);
3697 offset = off[nst];
3698 assert(offset >= header_size, "do not smash header");
3699 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3700 guarantee(ins_idx != 0, "must re-insert constant store");
3701 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3702 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3703 set_req(--ins_idx, st1);
3704 else
3705 ins_req(ins_idx, st1);
3706 }
3707 }
3708
3709 if (PrintCompilation && WizardMode)
3710 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3711 old_subword, old_long, new_int, new_long);
3712 if (C->log() != NULL)
3713 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3714 old_subword, old_long, new_int, new_long);
3715
3716 // Clean up any remaining occurrences of zmem:
3717 remove_extra_zeroes();
3718 }
3719
3720 // Explore forward from in(start) to find the first fully initialized
3721 // word, and return its offset. Skip groups of subword stores which
3722 // together initialize full words. If in(start) is itself part of a
3723 // fully initialized word, return the offset of in(start). If there
3724 // are no following full-word stores, or if something is fishy, return
3725 // a negative value.
3726 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3727 int int_map = 0;
3728 intptr_t int_map_off = 0;
3729 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3730
3731 for (uint i = start, limit = req(); i < limit; i++) {
3732 Node* st = in(i);
3733
3734 intptr_t st_off = get_store_offset(st, phase);
3735 if (st_off < 0) break; // return conservative answer
3736
3737 int st_size = st->as_Store()->memory_size();
3738 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3739 return st_off; // we found a complete word init
3740 }
3741
3742 // update the map:
3743
3744 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3745 if (this_int_off != int_map_off) {
3746 // reset the map:
3747 int_map = 0;
3748 int_map_off = this_int_off;
3749 }
3750
3751 int subword_off = st_off - this_int_off;
3752 int_map |= right_n_bits(st_size) << subword_off;
3753 if ((int_map & FULL_MAP) == FULL_MAP) {
3754 return this_int_off; // we found a complete word init
3755 }
3756
3757 // Did this store hit or cross the word boundary?
3758 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3759 if (next_int_off == this_int_off + BytesPerInt) {
3760 // We passed the current int, without fully initializing it.
3761 int_map_off = next_int_off;
3762 int_map >>= BytesPerInt;
3763 } else if (next_int_off > this_int_off + BytesPerInt) {
3764 // We passed the current and next int.
3765 return this_int_off + BytesPerInt;
3766 }
3767 }
3768
3769 return -1;
3770 }
3771
3772
3773 // Called when the associated AllocateNode is expanded into CFG.
3774 // At this point, we may perform additional optimizations.
3775 // Linearize the stores by ascending offset, to make memory
3776 // activity as coherent as possible.
3777 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3778 intptr_t header_size,
3779 Node* size_in_bytes,
3780 PhaseGVN* phase) {
3781 assert(!is_complete(), "not already complete");
3782 assert(stores_are_sane(phase), "");
3783 assert(allocation() != NULL, "must be present");
3784
3785 remove_extra_zeroes();
3786
3787 if (ReduceFieldZeroing || ReduceBulkZeroing)
3788 // reduce instruction count for common initialization patterns
3789 coalesce_subword_stores(header_size, size_in_bytes, phase);
3790
3791 Node* zmem = zero_memory(); // initially zero memory state
3792 Node* inits = zmem; // accumulating a linearized chain of inits
3793 #ifdef ASSERT
3794 intptr_t first_offset = allocation()->minimum_header_size();
3795 intptr_t last_init_off = first_offset; // previous init offset
3796 intptr_t last_init_end = first_offset; // previous init offset+size
3797 intptr_t last_tile_end = first_offset; // previous tile offset+size
3798 #endif
3799 intptr_t zeroes_done = header_size;
3800
3801 bool do_zeroing = true; // we might give up if inits are very sparse
3802 int big_init_gaps = 0; // how many large gaps have we seen?
3803
3804 if (ZeroTLAB) do_zeroing = false;
3805 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3806
3807 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3808 Node* st = in(i);
3809 intptr_t st_off = get_store_offset(st, phase);
3810 if (st_off < 0)
3811 break; // unknown junk in the inits
3812 if (st->in(MemNode::Memory) != zmem)
3813 break; // complicated store chains somehow in list
3814
3815 int st_size = st->as_Store()->memory_size();
3816 intptr_t next_init_off = st_off + st_size;
3817
3818 if (do_zeroing && zeroes_done < next_init_off) {
3819 // See if this store needs a zero before it or under it.
3820 intptr_t zeroes_needed = st_off;
3821
3822 if (st_size < BytesPerInt) {
3823 // Look for subword stores which only partially initialize words.
3824 // If we find some, we must lay down some word-level zeroes first,
3825 // underneath the subword stores.
3826 //
3827 // Examples:
3828 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3829 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3830 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3831 //
3832 // Note: coalesce_subword_stores may have already done this,
3833 // if it was prompted by constant non-zero subword initializers.
3834 // But this case can still arise with non-constant stores.
3835
3836 intptr_t next_full_store = find_next_fullword_store(i, phase);
3837
3838 // In the examples above:
3839 // in(i) p q r s x y z
3840 // st_off 12 13 14 15 12 13 14
3841 // st_size 1 1 1 1 1 1 1
3842 // next_full_s. 12 16 16 16 16 16 16
3843 // z's_done 12 16 16 16 12 16 12
3844 // z's_needed 12 16 16 16 16 16 16
3845 // zsize 0 0 0 0 4 0 4
3846 if (next_full_store < 0) {
3847 // Conservative tack: Zero to end of current word.
3848 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3849 } else {
3850 // Zero to beginning of next fully initialized word.
3851 // Or, don't zero at all, if we are already in that word.
3852 assert(next_full_store >= zeroes_needed, "must go forward");
3853 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3854 zeroes_needed = next_full_store;
3855 }
3856 }
3857
3858 if (zeroes_needed > zeroes_done) {
3859 intptr_t zsize = zeroes_needed - zeroes_done;
3860 // Do some incremental zeroing on rawmem, in parallel with inits.
3861 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3862 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3863 zeroes_done, zeroes_needed,
3864 phase);
3865 zeroes_done = zeroes_needed;
3866 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3867 do_zeroing = false; // leave the hole, next time
3868 }
3869 }
3870
3871 // Collect the store and move on:
3872 st->set_req(MemNode::Memory, inits);
3873 inits = st; // put it on the linearized chain
3874 set_req(i, zmem); // unhook from previous position
3875
3876 if (zeroes_done == st_off)
3877 zeroes_done = next_init_off;
3878
3879 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3880
3881 #ifdef ASSERT
3882 // Various order invariants. Weaker than stores_are_sane because
3883 // a large constant tile can be filled in by smaller non-constant stores.
3884 assert(st_off >= last_init_off, "inits do not reverse");
3885 last_init_off = st_off;
3886 const Type* val = NULL;
3887 if (st_size >= BytesPerInt &&
3888 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3889 (int)val->basic_type() < (int)T_OBJECT) {
3890 assert(st_off >= last_tile_end, "tiles do not overlap");
3891 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3892 last_tile_end = MAX2(last_tile_end, next_init_off);
3893 } else {
3894 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3895 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3896 assert(st_off >= last_init_end, "inits do not overlap");
3897 last_init_end = next_init_off; // it's a non-tile
3898 }
3899 #endif //ASSERT
3900 }
3901
3902 remove_extra_zeroes(); // clear out all the zmems left over
3903 add_req(inits);
3904
3905 if (!ZeroTLAB) {
3906 // If anything remains to be zeroed, zero it all now.
3907 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3908 // if it is the last unused 4 bytes of an instance, forget about it
3909 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3910 if (zeroes_done + BytesPerLong >= size_limit) {
3911 assert(allocation() != NULL, "");
3912 if (allocation()->Opcode() == Op_Allocate) {
3913 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3914 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3915 if (zeroes_done == k->layout_helper())
3916 zeroes_done = size_limit;
3917 }
3918 }
3919 if (zeroes_done < size_limit) {
3920 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3921 zeroes_done, size_in_bytes, phase);
3922 }
3923 }
3924
3925 set_complete(phase);
3926 return rawmem;
3927 }
3928
3929
3930 #ifdef ASSERT
3931 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3932 if (is_complete())
3933 return true; // stores could be anything at this point
3934 assert(allocation() != NULL, "must be present");
3935 intptr_t last_off = allocation()->minimum_header_size();
3936 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3937 Node* st = in(i);
3938 intptr_t st_off = get_store_offset(st, phase);
3939 if (st_off < 0) continue; // ignore dead garbage
3940 if (last_off > st_off) {
3941 tty->print_cr("*** bad store offset at %d: " INTX_FORMAT " > " INTX_FORMAT, i, last_off, st_off);
3942 this->dump(2);
3943 assert(false, "ascending store offsets");
3944 return false;
3945 }
3946 last_off = st_off + st->as_Store()->memory_size();
3947 }
3948 return true;
3949 }
3950 #endif //ASSERT
3951
3952
3953
3954
3955 //============================MergeMemNode=====================================
3956 //
3957 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3958 // contributing store or call operations. Each contributor provides the memory
3959 // state for a particular "alias type" (see Compile::alias_type). For example,
3960 // if a MergeMem has an input X for alias category #6, then any memory reference
3961 // to alias category #6 may use X as its memory state input, as an exact equivalent
3962 // to using the MergeMem as a whole.
3963 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3964 //
3965 // (Here, the <N> notation gives the index of the relevant adr_type.)
3966 //
3967 // In one special case (and more cases in the future), alias categories overlap.
3968 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3969 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3970 // it is exactly equivalent to that state W:
3971 // MergeMem(<Bot>: W) <==> W
3972 //
3973 // Usually, the merge has more than one input. In that case, where inputs
3974 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3975 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3976 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3977 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3978 //
3979 // A merge can take a "wide" memory state as one of its narrow inputs.
3980 // This simply means that the merge observes out only the relevant parts of
3981 // the wide input. That is, wide memory states arriving at narrow merge inputs
3982 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3983 //
3984 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3985 // and that memory slices "leak through":
3986 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3987 //
3988 // But, in such a cascade, repeated memory slices can "block the leak":
3989 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3990 //
3991 // In the last example, Y is not part of the combined memory state of the
3992 // outermost MergeMem. The system must, of course, prevent unschedulable
3993 // memory states from arising, so you can be sure that the state Y is somehow
3994 // a precursor to state Y'.
3995 //
3996 //
3997 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3998 // of each MergeMemNode array are exactly the numerical alias indexes, including
3999 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
4000 // Compile::alias_type (and kin) produce and manage these indexes.
4001 //
4002 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
4003 // (Note that this provides quick access to the top node inside MergeMem methods,
4004 // without the need to reach out via TLS to Compile::current.)
4005 //
4006 // As a consequence of what was just described, a MergeMem that represents a full
4007 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
4008 // containing all alias categories.
4009 //
4010 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
4011 //
4012 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
4013 // a memory state for the alias type <N>, or else the top node, meaning that
4014 // there is no particular input for that alias type. Note that the length of
4015 // a MergeMem is variable, and may be extended at any time to accommodate new
4016 // memory states at larger alias indexes. When merges grow, they are of course
4017 // filled with "top" in the unused in() positions.
4018 //
4019 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
4020 // (Top was chosen because it works smoothly with passes like GCM.)
4021 //
4022 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
4023 // the type of random VM bits like TLS references.) Since it is always the
4024 // first non-Bot memory slice, some low-level loops use it to initialize an
4025 // index variable: for (i = AliasIdxRaw; i < req(); i++).
4026 //
4027 //
4028 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
4029 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
4030 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
4031 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
4032 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
4033 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
4034 //
4035 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
4036 // really that different from the other memory inputs. An abbreviation called
4037 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
4038 //
4039 //
4040 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
4041 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
4042 // that "emerges though" the base memory will be marked as excluding the alias types
4043 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
4044 //
4045 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
4046 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
4047 //
4048 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
4049 // (It is currently unimplemented.) As you can see, the resulting merge is
4050 // actually a disjoint union of memory states, rather than an overlay.
4051 //
4052
4053 //------------------------------MergeMemNode-----------------------------------
4054 Node* MergeMemNode::make_empty_memory() {
4055 Node* empty_memory = (Node*) Compile::current()->top();
4056 assert(empty_memory->is_top(), "correct sentinel identity");
4057 return empty_memory;
4058 }
4059
4060 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
4061 init_class_id(Class_MergeMem);
4062 // all inputs are nullified in Node::Node(int)
4063 // set_input(0, NULL); // no control input
4064
4065 // Initialize the edges uniformly to top, for starters.
4066 Node* empty_mem = make_empty_memory();
4067 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
4068 init_req(i,empty_mem);
4069 }
4070 assert(empty_memory() == empty_mem, "");
4071
4072 if( new_base != NULL && new_base->is_MergeMem() ) {
4073 MergeMemNode* mdef = new_base->as_MergeMem();
4074 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
4075 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
4076 mms.set_memory(mms.memory2());
4077 }
4078 assert(base_memory() == mdef->base_memory(), "");
4079 } else {
4080 set_base_memory(new_base);
4081 }
4082 }
4083
4084 // Make a new, untransformed MergeMem with the same base as 'mem'.
4085 // If mem is itself a MergeMem, populate the result with the same edges.
4086 MergeMemNode* MergeMemNode::make(Node* mem) {
4087 return new MergeMemNode(mem);
4088 }
4089
4090 //------------------------------cmp--------------------------------------------
4091 uint MergeMemNode::hash() const { return NO_HASH; }
4092 uint MergeMemNode::cmp( const Node &n ) const {
4093 return (&n == this); // Always fail except on self
4094 }
4095
4096 //------------------------------Identity---------------------------------------
4097 Node* MergeMemNode::Identity(PhaseTransform *phase) {
4098 // Identity if this merge point does not record any interesting memory
4099 // disambiguations.
4100 Node* base_mem = base_memory();
4101 Node* empty_mem = empty_memory();
4102 if (base_mem != empty_mem) { // Memory path is not dead?
4103 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4104 Node* mem = in(i);
4105 if (mem != empty_mem && mem != base_mem) {
4106 return this; // Many memory splits; no change
4107 }
4108 }
4109 }
4110 return base_mem; // No memory splits; ID on the one true input
4111 }
4112
4113 //------------------------------Ideal------------------------------------------
4114 // This method is invoked recursively on chains of MergeMem nodes
4115 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4116 // Remove chain'd MergeMems
4117 //
4118 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
4119 // relative to the "in(Bot)". Since we are patching both at the same time,
4120 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
4121 // but rewrite each "in(i)" relative to the new "in(Bot)".
4122 Node *progress = NULL;
4123
4124
4125 Node* old_base = base_memory();
4126 Node* empty_mem = empty_memory();
4127 if (old_base == empty_mem)
4128 return NULL; // Dead memory path.
4129
4130 MergeMemNode* old_mbase;
4131 if (old_base != NULL && old_base->is_MergeMem())
4132 old_mbase = old_base->as_MergeMem();
4133 else
4134 old_mbase = NULL;
4135 Node* new_base = old_base;
4136
4137 // simplify stacked MergeMems in base memory
4138 if (old_mbase) new_base = old_mbase->base_memory();
4139
4140 // the base memory might contribute new slices beyond my req()
4141 if (old_mbase) grow_to_match(old_mbase);
4142
4143 // Look carefully at the base node if it is a phi.
4144 PhiNode* phi_base;
4145 if (new_base != NULL && new_base->is_Phi())
4146 phi_base = new_base->as_Phi();
4147 else
4148 phi_base = NULL;
4149
4150 Node* phi_reg = NULL;
4151 uint phi_len = (uint)-1;
4152 if (phi_base != NULL && !phi_base->is_copy()) {
4153 // do not examine phi if degraded to a copy
4154 phi_reg = phi_base->region();
4155 phi_len = phi_base->req();
4156 // see if the phi is unfinished
4157 for (uint i = 1; i < phi_len; i++) {
4158 if (phi_base->in(i) == NULL) {
4159 // incomplete phi; do not look at it yet!
4160 phi_reg = NULL;
4161 phi_len = (uint)-1;
4162 break;
4163 }
4164 }
4165 }
4166
4167 // Note: We do not call verify_sparse on entry, because inputs
4168 // can normalize to the base_memory via subsume_node or similar
4169 // mechanisms. This method repairs that damage.
4170
4171 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
4172
4173 // Look at each slice.
4174 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4175 Node* old_in = in(i);
4176 // calculate the old memory value
4177 Node* old_mem = old_in;
4178 if (old_mem == empty_mem) old_mem = old_base;
4179 assert(old_mem == memory_at(i), "");
4180
4181 // maybe update (reslice) the old memory value
4182
4183 // simplify stacked MergeMems
4184 Node* new_mem = old_mem;
4185 MergeMemNode* old_mmem;
4186 if (old_mem != NULL && old_mem->is_MergeMem())
4187 old_mmem = old_mem->as_MergeMem();
4188 else
4189 old_mmem = NULL;
4190 if (old_mmem == this) {
4191 // This can happen if loops break up and safepoints disappear.
4192 // A merge of BotPtr (default) with a RawPtr memory derived from a
4193 // safepoint can be rewritten to a merge of the same BotPtr with
4194 // the BotPtr phi coming into the loop. If that phi disappears
4195 // also, we can end up with a self-loop of the mergemem.
4196 // In general, if loops degenerate and memory effects disappear,
4197 // a mergemem can be left looking at itself. This simply means
4198 // that the mergemem's default should be used, since there is
4199 // no longer any apparent effect on this slice.
4200 // Note: If a memory slice is a MergeMem cycle, it is unreachable
4201 // from start. Update the input to TOP.
4202 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4203 }
4204 else if (old_mmem != NULL) {
4205 new_mem = old_mmem->memory_at(i);
4206 }
4207 // else preceding memory was not a MergeMem
4208
4209 // replace equivalent phis (unfortunately, they do not GVN together)
4210 if (new_mem != NULL && new_mem != new_base &&
4211 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4212 if (new_mem->is_Phi()) {
4213 PhiNode* phi_mem = new_mem->as_Phi();
4214 for (uint i = 1; i < phi_len; i++) {
4215 if (phi_base->in(i) != phi_mem->in(i)) {
4216 phi_mem = NULL;
4217 break;
4218 }
4219 }
4220 if (phi_mem != NULL) {
4221 // equivalent phi nodes; revert to the def
4222 new_mem = new_base;
4223 }
4224 }
4225 }
4226
4227 // maybe store down a new value
4228 Node* new_in = new_mem;
4229 if (new_in == new_base) new_in = empty_mem;
4230
4231 if (new_in != old_in) {
4232 // Warning: Do not combine this "if" with the previous "if"
4233 // A memory slice might have be be rewritten even if it is semantically
4234 // unchanged, if the base_memory value has changed.
4235 set_req(i, new_in);
4236 progress = this; // Report progress
4237 }
4238 }
4239
4240 if (new_base != old_base) {
4241 set_req(Compile::AliasIdxBot, new_base);
4242 // Don't use set_base_memory(new_base), because we need to update du.
4243 assert(base_memory() == new_base, "");
4244 progress = this;
4245 }
4246
4247 if( base_memory() == this ) {
4248 // a self cycle indicates this memory path is dead
4249 set_req(Compile::AliasIdxBot, empty_mem);
4250 }
4251
4252 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4253 // Recursion must occur after the self cycle check above
4254 if( base_memory()->is_MergeMem() ) {
4255 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4256 Node *m = phase->transform(new_mbase); // Rollup any cycles
4257 if( m != NULL && (m->is_top() ||
4258 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4259 // propagate rollup of dead cycle to self
4260 set_req(Compile::AliasIdxBot, empty_mem);
4261 }
4262 }
4263
4264 if( base_memory() == empty_mem ) {
4265 progress = this;
4266 // Cut inputs during Parse phase only.
4267 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4268 if( !can_reshape ) {
4269 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4270 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4271 }
4272 }
4273 }
4274
4275 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4276 // Check if PhiNode::Ideal's "Split phis through memory merges"
4277 // transform should be attempted. Look for this->phi->this cycle.
4278 uint merge_width = req();
4279 if (merge_width > Compile::AliasIdxRaw) {
4280 PhiNode* phi = base_memory()->as_Phi();
4281 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4282 if (phi->in(i) == this) {
4283 phase->is_IterGVN()->_worklist.push(phi);
4284 break;
4285 }
4286 }
4287 }
4288 }
4289
4290 assert(progress || verify_sparse(), "please, no dups of base");
4291 return progress;
4292 }
4293
4294 //-------------------------set_base_memory-------------------------------------
4295 void MergeMemNode::set_base_memory(Node *new_base) {
4296 Node* empty_mem = empty_memory();
4297 set_req(Compile::AliasIdxBot, new_base);
4298 assert(memory_at(req()) == new_base, "must set default memory");
4299 // Clear out other occurrences of new_base:
4300 if (new_base != empty_mem) {
4301 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4302 if (in(i) == new_base) set_req(i, empty_mem);
4303 }
4304 }
4305 }
4306
4307 //------------------------------out_RegMask------------------------------------
4308 const RegMask &MergeMemNode::out_RegMask() const {
4309 return RegMask::Empty;
4310 }
4311
4312 //------------------------------dump_spec--------------------------------------
4313 #ifndef PRODUCT
4314 void MergeMemNode::dump_spec(outputStream *st) const {
4315 st->print(" {");
4316 Node* base_mem = base_memory();
4317 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4318 Node* mem = (in(i) != NULL) ? memory_at(i) : base_mem;
4319 if (mem == base_mem) { st->print(" -"); continue; }
4320 st->print( " N%d:", mem->_idx );
4321 Compile::current()->get_adr_type(i)->dump_on(st);
4322 }
4323 st->print(" }");
4324 }
4325 #endif // !PRODUCT
4326
4327
4328 #ifdef ASSERT
4329 static bool might_be_same(Node* a, Node* b) {
4330 if (a == b) return true;
4331 if (!(a->is_Phi() || b->is_Phi())) return false;
4332 // phis shift around during optimization
4333 return true; // pretty stupid...
4334 }
4335
4336 // verify a narrow slice (either incoming or outgoing)
4337 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4338 if (!VerifyAliases) return; // don't bother to verify unless requested
4339 if (is_error_reported()) return; // muzzle asserts when debugging an error
4340 if (Node::in_dump()) return; // muzzle asserts when printing
4341 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4342 assert(n != NULL, "");
4343 // Elide intervening MergeMem's
4344 while (n->is_MergeMem()) {
4345 n = n->as_MergeMem()->memory_at(alias_idx);
4346 }
4347 Compile* C = Compile::current();
4348 const TypePtr* n_adr_type = n->adr_type();
4349 if (n == m->empty_memory()) {
4350 // Implicit copy of base_memory()
4351 } else if (n_adr_type != TypePtr::BOTTOM) {
4352 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4353 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4354 } else {
4355 // A few places like make_runtime_call "know" that VM calls are narrow,
4356 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4357 bool expected_wide_mem = false;
4358 if (n == m->base_memory()) {
4359 expected_wide_mem = true;
4360 } else if (alias_idx == Compile::AliasIdxRaw ||
4361 n == m->memory_at(Compile::AliasIdxRaw)) {
4362 expected_wide_mem = true;
4363 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4364 // memory can "leak through" calls on channels that
4365 // are write-once. Allow this also.
4366 expected_wide_mem = true;
4367 }
4368 assert(expected_wide_mem, "expected narrow slice replacement");
4369 }
4370 }
4371 #else // !ASSERT
4372 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
4373 #endif
4374
4375
4376 //-----------------------------memory_at---------------------------------------
4377 Node* MergeMemNode::memory_at(uint alias_idx) const {
4378 assert(alias_idx >= Compile::AliasIdxRaw ||
4379 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4380 "must avoid base_memory and AliasIdxTop");
4381
4382 // Otherwise, it is a narrow slice.
4383 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4384 Compile *C = Compile::current();
4385 if (is_empty_memory(n)) {
4386 // the array is sparse; empty slots are the "top" node
4387 n = base_memory();
4388 assert(Node::in_dump()
4389 || n == NULL || n->bottom_type() == Type::TOP
4390 || n->adr_type() == NULL // address is TOP
4391 || n->adr_type() == TypePtr::BOTTOM
4392 || n->adr_type() == TypeRawPtr::BOTTOM
4393 || Compile::current()->AliasLevel() == 0,
4394 "must be a wide memory");
4395 // AliasLevel == 0 if we are organizing the memory states manually.
4396 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4397 } else {
4398 // make sure the stored slice is sane
4399 #ifdef ASSERT
4400 if (is_error_reported() || Node::in_dump()) {
4401 } else if (might_be_same(n, base_memory())) {
4402 // Give it a pass: It is a mostly harmless repetition of the base.
4403 // This can arise normally from node subsumption during optimization.
4404 } else {
4405 verify_memory_slice(this, alias_idx, n);
4406 }
4407 #endif
4408 }
4409 return n;
4410 }
4411
4412 //---------------------------set_memory_at-------------------------------------
4413 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4414 verify_memory_slice(this, alias_idx, n);
4415 Node* empty_mem = empty_memory();
4416 if (n == base_memory()) n = empty_mem; // collapse default
4417 uint need_req = alias_idx+1;
4418 if (req() < need_req) {
4419 if (n == empty_mem) return; // already the default, so do not grow me
4420 // grow the sparse array
4421 do {
4422 add_req(empty_mem);
4423 } while (req() < need_req);
4424 }
4425 set_req( alias_idx, n );
4426 }
4427
4428
4429
4430 //--------------------------iteration_setup------------------------------------
4431 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4432 if (other != NULL) {
4433 grow_to_match(other);
4434 // invariant: the finite support of mm2 is within mm->req()
4435 #ifdef ASSERT
4436 for (uint i = req(); i < other->req(); i++) {
4437 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4438 }
4439 #endif
4440 }
4441 // Replace spurious copies of base_memory by top.
4442 Node* base_mem = base_memory();
4443 if (base_mem != NULL && !base_mem->is_top()) {
4444 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4445 if (in(i) == base_mem)
4446 set_req(i, empty_memory());
4447 }
4448 }
4449 }
4450
4451 //---------------------------grow_to_match-------------------------------------
4452 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4453 Node* empty_mem = empty_memory();
4454 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4455 // look for the finite support of the other memory
4456 for (uint i = other->req(); --i >= req(); ) {
4457 if (other->in(i) != empty_mem) {
4458 uint new_len = i+1;
4459 while (req() < new_len) add_req(empty_mem);
4460 break;
4461 }
4462 }
4463 }
4464
4465 //---------------------------verify_sparse-------------------------------------
4466 #ifndef PRODUCT
4467 bool MergeMemNode::verify_sparse() const {
4468 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4469 Node* base_mem = base_memory();
4470 // The following can happen in degenerate cases, since empty==top.
4471 if (is_empty_memory(base_mem)) return true;
4472 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4473 assert(in(i) != NULL, "sane slice");
4474 if (in(i) == base_mem) return false; // should have been the sentinel value!
4475 }
4476 return true;
4477 }
4478
4479 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4480 Node* n;
4481 n = mm->in(idx);
4482 if (mem == n) return true; // might be empty_memory()
4483 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4484 if (mem == n) return true;
4485 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4486 if (mem == n) return true;
4487 if (n == NULL) break;
4488 }
4489 return false;
4490 }
4491 #endif // !PRODUCT