1 /*
2 * Copyright (c) 1997, 2012, 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/cfgnode.hpp"
32 #include "opto/compile.hpp"
33 #include "opto/connode.hpp"
34 #include "opto/loopnode.hpp"
35 #include "opto/machnode.hpp"
36 #include "opto/matcher.hpp"
37 #include "opto/memnode.hpp"
38 #include "opto/mulnode.hpp"
39 #include "opto/phaseX.hpp"
40 #include "opto/regmask.hpp"
41
42 // Portions of code courtesy of Clifford Click
43
44 // Optimization - Graph Style
45
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
47
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
50
51 const TypePtr *MemNode::adr_type() const {
52 Node* adr = in(Address);
53 const TypePtr* cross_check = NULL;
54 DEBUG_ONLY(cross_check = _adr_type);
55 return calculate_adr_type(adr->bottom_type(), cross_check);
56 }
57
58 #ifndef PRODUCT
59 void MemNode::dump_spec(outputStream *st) const {
60 if (in(Address) == NULL) return; // node is dead
61 #ifndef ASSERT
62 // fake the missing field
63 const TypePtr* _adr_type = NULL;
64 if (in(Address) != NULL)
65 _adr_type = in(Address)->bottom_type()->isa_ptr();
66 #endif
67 dump_adr_type(this, _adr_type, st);
68
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
73
74 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
75 st->print(" @");
76 if (adr_type == NULL) {
77 st->print("NULL");
78 } else {
79 adr_type->dump_on(st);
80 Compile* C = Compile::current();
81 Compile::AliasType* atp = NULL;
82 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
83 if (atp == NULL)
84 st->print(", idx=?\?;");
85 else if (atp->index() == Compile::AliasIdxBot)
86 st->print(", idx=Bot;");
87 else if (atp->index() == Compile::AliasIdxTop)
88 st->print(", idx=Top;");
89 else if (atp->index() == Compile::AliasIdxRaw)
90 st->print(", idx=Raw;");
91 else {
92 ciField* field = atp->field();
93 if (field) {
94 st->print(", name=");
95 field->print_name_on(st);
96 }
97 st->print(", idx=%d;", atp->index());
98 }
99 }
100 }
101
102 extern void print_alias_types();
103
104 #endif
105
106 Node *MemNode::optimize_simple_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
107 const TypeOopPtr *tinst = t_adr->isa_oopptr();
108 if (tinst == NULL || !tinst->is_known_instance_field())
109 return mchain; // don't try to optimize non-instance types
110 uint instance_id = tinst->instance_id();
111 Node *start_mem = phase->C->start()->proj_out(TypeFunc::Memory);
112 Node *prev = NULL;
113 Node *result = mchain;
114 while (prev != result) {
115 prev = result;
116 if (result == start_mem)
117 break; // hit one of our sentinels
118 // skip over a call which does not affect this memory slice
119 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
120 Node *proj_in = result->in(0);
121 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
122 break; // hit one of our sentinels
123 } else if (proj_in->is_Call()) {
124 CallNode *call = proj_in->as_Call();
125 if (!call->may_modify(t_adr, phase)) {
126 result = call->in(TypeFunc::Memory);
127 }
128 } else if (proj_in->is_Initialize()) {
129 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
130 // Stop if this is the initialization for the object instance which
131 // which contains this memory slice, otherwise skip over it.
132 if (alloc != NULL && alloc->_idx != instance_id) {
133 result = proj_in->in(TypeFunc::Memory);
134 }
135 } else if (proj_in->is_MemBar()) {
136 result = proj_in->in(TypeFunc::Memory);
137 } else {
138 assert(false, "unexpected projection");
139 }
140 } else if (result->is_ClearArray()) {
141 if (!ClearArrayNode::step_through(&result, instance_id, phase)) {
142 // Can not bypass initialization of the instance
143 // we are looking for.
144 break;
145 }
146 // Otherwise skip it (the call updated 'result' value).
147 } else if (result->is_MergeMem()) {
148 result = step_through_mergemem(phase, result->as_MergeMem(), t_adr, NULL, tty);
149 }
150 }
151 return result;
152 }
153
154 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, PhaseGVN *phase) {
155 const TypeOopPtr *t_oop = t_adr->isa_oopptr();
156 bool is_instance = (t_oop != NULL) && t_oop->is_known_instance_field();
157 PhaseIterGVN *igvn = phase->is_IterGVN();
158 Node *result = mchain;
159 result = optimize_simple_memory_chain(result, t_adr, phase);
160 if (is_instance && igvn != NULL && result->is_Phi()) {
161 PhiNode *mphi = result->as_Phi();
162 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
163 const TypePtr *t = mphi->adr_type();
164 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
165 t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
166 t->is_oopptr()->cast_to_exactness(true)
167 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
168 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop) {
169 // clone the Phi with our address type
170 result = mphi->split_out_instance(t_adr, igvn);
171 } else {
172 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
173 }
174 }
175 return result;
176 }
177
178 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
179 uint alias_idx = phase->C->get_alias_index(tp);
180 Node *mem = mmem;
181 #ifdef ASSERT
182 {
183 // Check that current type is consistent with the alias index used during graph construction
184 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
185 bool consistent = adr_check == NULL || adr_check->empty() ||
186 phase->C->must_alias(adr_check, alias_idx );
187 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
188 if( !consistent && adr_check != NULL && !adr_check->empty() &&
189 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
190 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
191 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
192 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
193 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
194 // don't assert if it is dead code.
195 consistent = true;
196 }
197 if( !consistent ) {
198 st->print("alias_idx==%d, adr_check==", alias_idx);
199 if( adr_check == NULL ) {
200 st->print("NULL");
201 } else {
202 adr_check->dump();
203 }
204 st->cr();
205 print_alias_types();
206 assert(consistent, "adr_check must match alias idx");
207 }
208 }
209 #endif
210 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
211 // means an array I have not precisely typed yet. Do not do any
212 // alias stuff with it any time soon.
213 const TypeOopPtr *toop = tp->isa_oopptr();
214 if( tp->base() != Type::AnyPtr &&
215 !(toop &&
216 toop->klass() != NULL &&
217 toop->klass()->is_java_lang_Object() &&
218 toop->offset() == Type::OffsetBot) ) {
219 // compress paths and change unreachable cycles to TOP
220 // If not, we can update the input infinitely along a MergeMem cycle
221 // Equivalent code in PhiNode::Ideal
222 Node* m = phase->transform(mmem);
223 // If transformed to a MergeMem, get the desired slice
224 // Otherwise the returned node represents memory for every slice
225 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
226 // Update input if it is progress over what we have now
227 }
228 return mem;
229 }
230
231 //--------------------------Ideal_common---------------------------------------
232 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
233 // Unhook non-raw memories from complete (macro-expanded) initializations.
234 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
235 // If our control input is a dead region, kill all below the region
236 Node *ctl = in(MemNode::Control);
237 if (ctl && remove_dead_region(phase, can_reshape))
238 return this;
239 ctl = in(MemNode::Control);
240 // Don't bother trying to transform a dead node
241 if( ctl && ctl->is_top() ) return NodeSentinel;
242
243 PhaseIterGVN *igvn = phase->is_IterGVN();
244 // Wait if control on the worklist.
245 if (ctl && can_reshape && igvn != NULL) {
246 Node* bol = NULL;
247 Node* cmp = NULL;
248 if (ctl->in(0)->is_If()) {
249 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
250 bol = ctl->in(0)->in(1);
251 if (bol->is_Bool())
252 cmp = ctl->in(0)->in(1)->in(1);
253 }
254 if (igvn->_worklist.member(ctl) ||
255 (bol != NULL && igvn->_worklist.member(bol)) ||
256 (cmp != NULL && igvn->_worklist.member(cmp)) ) {
257 // This control path may be dead.
258 // Delay this memory node transformation until the control is processed.
259 phase->is_IterGVN()->_worklist.push(this);
260 return NodeSentinel; // caller will return NULL
261 }
262 }
263 // Ignore if memory is dead, or self-loop
264 Node *mem = in(MemNode::Memory);
265 if( phase->type( mem ) == Type::TOP ) return NodeSentinel; // caller will return NULL
266 assert( mem != this, "dead loop in MemNode::Ideal" );
267
268 if (can_reshape && igvn != NULL && igvn->_worklist.member(mem)) {
269 // This memory slice may be dead.
270 // Delay this mem node transformation until the memory is processed.
271 phase->is_IterGVN()->_worklist.push(this);
272 return NodeSentinel; // caller will return NULL
273 }
274
275 Node *address = in(MemNode::Address);
276 const Type *t_adr = phase->type( address );
277 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
278
279 if( can_reshape && igvn != NULL &&
280 (igvn->_worklist.member(address) ||
281 igvn->_worklist.size() > 0 && (phase->type(address) != adr_type())) ) {
282 // The address's base and type may change when the address is processed.
283 // Delay this mem node transformation until the address is processed.
284 phase->is_IterGVN()->_worklist.push(this);
285 return NodeSentinel; // caller will return NULL
286 }
287
288 // Do NOT remove or optimize the next lines: ensure a new alias index
289 // is allocated for an oop pointer type before Escape Analysis.
290 // Note: C++ will not remove it since the call has side effect.
291 if ( t_adr->isa_oopptr() ) {
292 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
293 }
294
295 #ifdef ASSERT
296 Node* base = NULL;
297 if (address->is_AddP())
298 base = address->in(AddPNode::Base);
299 assert(base == NULL || t_adr->isa_rawptr() ||
300 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
301 #endif
302
303 // Avoid independent memory operations
304 Node* old_mem = mem;
305
306 // The code which unhooks non-raw memories from complete (macro-expanded)
307 // initializations was removed. After macro-expansion all stores catched
308 // by Initialize node became raw stores and there is no information
309 // which memory slices they modify. So it is unsafe to move any memory
310 // operation above these stores. Also in most cases hooked non-raw memories
311 // were already unhooked by using information from detect_ptr_independence()
312 // and find_previous_store().
313
314 if (mem->is_MergeMem()) {
315 MergeMemNode* mmem = mem->as_MergeMem();
316 const TypePtr *tp = t_adr->is_ptr();
317
318 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
319 }
320
321 if (mem != old_mem) {
322 set_req(MemNode::Memory, mem);
323 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
324 return this;
325 }
326
327 // let the subclass continue analyzing...
328 return NULL;
329 }
330
331 // Helper function for proving some simple control dominations.
332 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
333 // Already assumes that 'dom' is available at 'sub', and that 'sub'
334 // is not a constant (dominated by the method's StartNode).
335 // Used by MemNode::find_previous_store to prove that the
336 // control input of a memory operation predates (dominates)
337 // an allocation it wants to look past.
338 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
339 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
340 return false; // Conservative answer for dead code
341
342 // Check 'dom'. Skip Proj and CatchProj nodes.
343 dom = dom->find_exact_control(dom);
344 if (dom == NULL || dom->is_top())
345 return false; // Conservative answer for dead code
346
347 if (dom == sub) {
348 // For the case when, for example, 'sub' is Initialize and the original
349 // 'dom' is Proj node of the 'sub'.
350 return false;
351 }
352
353 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
354 return true;
355
356 // 'dom' dominates 'sub' if its control edge and control edges
357 // of all its inputs dominate or equal to sub's control edge.
358
359 // Currently 'sub' is either Allocate, Initialize or Start nodes.
360 // Or Region for the check in LoadNode::Ideal();
361 // 'sub' should have sub->in(0) != NULL.
362 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
363 sub->is_Region(), "expecting only these nodes");
364
365 // Get control edge of 'sub'.
366 Node* orig_sub = sub;
367 sub = sub->find_exact_control(sub->in(0));
368 if (sub == NULL || sub->is_top())
369 return false; // Conservative answer for dead code
370
371 assert(sub->is_CFG(), "expecting control");
372
373 if (sub == dom)
374 return true;
375
376 if (sub->is_Start() || sub->is_Root())
377 return false;
378
379 {
380 // Check all control edges of 'dom'.
381
382 ResourceMark rm;
383 Arena* arena = Thread::current()->resource_area();
384 Node_List nlist(arena);
385 Unique_Node_List dom_list(arena);
386
387 dom_list.push(dom);
388 bool only_dominating_controls = false;
389
390 for (uint next = 0; next < dom_list.size(); next++) {
391 Node* n = dom_list.at(next);
392 if (n == orig_sub)
393 return false; // One of dom's inputs dominated by sub.
394 if (!n->is_CFG() && n->pinned()) {
395 // Check only own control edge for pinned non-control nodes.
396 n = n->find_exact_control(n->in(0));
397 if (n == NULL || n->is_top())
398 return false; // Conservative answer for dead code
399 assert(n->is_CFG(), "expecting control");
400 dom_list.push(n);
401 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
402 only_dominating_controls = true;
403 } else if (n->is_CFG()) {
404 if (n->dominates(sub, nlist))
405 only_dominating_controls = true;
406 else
407 return false;
408 } else {
409 // First, own control edge.
410 Node* m = n->find_exact_control(n->in(0));
411 if (m != NULL) {
412 if (m->is_top())
413 return false; // Conservative answer for dead code
414 dom_list.push(m);
415 }
416 // Now, the rest of edges.
417 uint cnt = n->req();
418 for (uint i = 1; i < cnt; i++) {
419 m = n->find_exact_control(n->in(i));
420 if (m == NULL || m->is_top())
421 continue;
422 dom_list.push(m);
423 }
424 }
425 }
426 return only_dominating_controls;
427 }
428 }
429
430 //---------------------detect_ptr_independence---------------------------------
431 // Used by MemNode::find_previous_store to prove that two base
432 // pointers are never equal.
433 // The pointers are accompanied by their associated allocations,
434 // if any, which have been previously discovered by the caller.
435 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
436 Node* p2, AllocateNode* a2,
437 PhaseTransform* phase) {
438 // Attempt to prove that these two pointers cannot be aliased.
439 // They may both manifestly be allocations, and they should differ.
440 // Or, if they are not both allocations, they can be distinct constants.
441 // Otherwise, one is an allocation and the other a pre-existing value.
442 if (a1 == NULL && a2 == NULL) { // neither an allocation
443 return (p1 != p2) && p1->is_Con() && p2->is_Con();
444 } else if (a1 != NULL && a2 != NULL) { // both allocations
445 return (a1 != a2);
446 } else if (a1 != NULL) { // one allocation a1
447 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
448 return all_controls_dominate(p2, a1);
449 } else { //(a2 != NULL) // one allocation a2
450 return all_controls_dominate(p1, a2);
451 }
452 return false;
453 }
454
455
456 // The logic for reordering loads and stores uses four steps:
457 // (a) Walk carefully past stores and initializations which we
458 // can prove are independent of this load.
459 // (b) Observe that the next memory state makes an exact match
460 // with self (load or store), and locate the relevant store.
461 // (c) Ensure that, if we were to wire self directly to the store,
462 // the optimizer would fold it up somehow.
463 // (d) Do the rewiring, and return, depending on some other part of
464 // the optimizer to fold up the load.
465 // This routine handles steps (a) and (b). Steps (c) and (d) are
466 // specific to loads and stores, so they are handled by the callers.
467 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
468 //
469 Node* MemNode::find_previous_store(PhaseTransform* phase) {
470 Node* ctrl = in(MemNode::Control);
471 Node* adr = in(MemNode::Address);
472 intptr_t offset = 0;
473 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
474 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
475
476 if (offset == Type::OffsetBot)
477 return NULL; // cannot unalias unless there are precise offsets
478
479 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
480
481 intptr_t size_in_bytes = memory_size();
482
483 Node* mem = in(MemNode::Memory); // start searching here...
484
485 int cnt = 50; // Cycle limiter
486 for (;;) { // While we can dance past unrelated stores...
487 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
488
489 if (mem->is_Store()) {
490 Node* st_adr = mem->in(MemNode::Address);
491 intptr_t st_offset = 0;
492 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
493 if (st_base == NULL)
494 break; // inscrutable pointer
495 if (st_offset != offset && st_offset != Type::OffsetBot) {
496 const int MAX_STORE = BytesPerLong;
497 if (st_offset >= offset + size_in_bytes ||
498 st_offset <= offset - MAX_STORE ||
499 st_offset <= offset - mem->as_Store()->memory_size()) {
500 // Success: The offsets are provably independent.
501 // (You may ask, why not just test st_offset != offset and be done?
502 // The answer is that stores of different sizes can co-exist
503 // in the same sequence of RawMem effects. We sometimes initialize
504 // a whole 'tile' of array elements with a single jint or jlong.)
505 mem = mem->in(MemNode::Memory);
506 continue; // (a) advance through independent store memory
507 }
508 }
509 if (st_base != base &&
510 detect_ptr_independence(base, alloc,
511 st_base,
512 AllocateNode::Ideal_allocation(st_base, phase),
513 phase)) {
514 // Success: The bases are provably independent.
515 mem = mem->in(MemNode::Memory);
516 continue; // (a) advance through independent store memory
517 }
518
519 // (b) At this point, if the bases or offsets do not agree, we lose,
520 // since we have not managed to prove 'this' and 'mem' independent.
521 if (st_base == base && st_offset == offset) {
522 return mem; // let caller handle steps (c), (d)
523 }
524
525 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
526 InitializeNode* st_init = mem->in(0)->as_Initialize();
527 AllocateNode* st_alloc = st_init->allocation();
528 if (st_alloc == NULL)
529 break; // something degenerated
530 bool known_identical = false;
531 bool known_independent = false;
532 if (alloc == st_alloc)
533 known_identical = true;
534 else if (alloc != NULL)
535 known_independent = true;
536 else if (all_controls_dominate(this, st_alloc))
537 known_independent = true;
538
539 if (known_independent) {
540 // The bases are provably independent: Either they are
541 // manifestly distinct allocations, or else the control
542 // of this load dominates the store's allocation.
543 int alias_idx = phase->C->get_alias_index(adr_type());
544 if (alias_idx == Compile::AliasIdxRaw) {
545 mem = st_alloc->in(TypeFunc::Memory);
546 } else {
547 mem = st_init->memory(alias_idx);
548 }
549 continue; // (a) advance through independent store memory
550 }
551
552 // (b) at this point, if we are not looking at a store initializing
553 // the same allocation we are loading from, we lose.
554 if (known_identical) {
555 // From caller, can_see_stored_value will consult find_captured_store.
556 return mem; // let caller handle steps (c), (d)
557 }
558
559 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
560 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
561 if (mem->is_Proj() && mem->in(0)->is_Call()) {
562 CallNode *call = mem->in(0)->as_Call();
563 if (!call->may_modify(addr_t, phase)) {
564 mem = call->in(TypeFunc::Memory);
565 continue; // (a) advance through independent call memory
566 }
567 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
568 mem = mem->in(0)->in(TypeFunc::Memory);
569 continue; // (a) advance through independent MemBar memory
570 } else if (mem->is_ClearArray()) {
571 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
572 // (the call updated 'mem' value)
573 continue; // (a) advance through independent allocation memory
574 } else {
575 // Can not bypass initialization of the instance
576 // we are looking for.
577 return mem;
578 }
579 } else if (mem->is_MergeMem()) {
580 int alias_idx = phase->C->get_alias_index(adr_type());
581 mem = mem->as_MergeMem()->memory_at(alias_idx);
582 continue; // (a) advance through independent MergeMem memory
583 }
584 }
585
586 // Unless there is an explicit 'continue', we must bail out here,
587 // because 'mem' is an inscrutable memory state (e.g., a call).
588 break;
589 }
590
591 return NULL; // bail out
592 }
593
594 //----------------------calculate_adr_type-------------------------------------
595 // Helper function. Notices when the given type of address hits top or bottom.
596 // Also, asserts a cross-check of the type against the expected address type.
597 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
598 if (t == Type::TOP) return NULL; // does not touch memory any more?
599 #ifdef PRODUCT
600 cross_check = NULL;
601 #else
602 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
603 #endif
604 const TypePtr* tp = t->isa_ptr();
605 if (tp == NULL) {
606 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
607 return TypePtr::BOTTOM; // touches lots of memory
608 } else {
609 #ifdef ASSERT
610 // %%%% [phh] We don't check the alias index if cross_check is
611 // TypeRawPtr::BOTTOM. Needs to be investigated.
612 if (cross_check != NULL &&
613 cross_check != TypePtr::BOTTOM &&
614 cross_check != TypeRawPtr::BOTTOM) {
615 // Recheck the alias index, to see if it has changed (due to a bug).
616 Compile* C = Compile::current();
617 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
618 "must stay in the original alias category");
619 // The type of the address must be contained in the adr_type,
620 // disregarding "null"-ness.
621 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
622 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
623 assert(cross_check->meet(tp_notnull) == cross_check,
624 "real address must not escape from expected memory type");
625 }
626 #endif
627 return tp;
628 }
629 }
630
631 //------------------------adr_phi_is_loop_invariant----------------------------
632 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
633 // loop is loop invariant. Make a quick traversal of Phi and associated
634 // CastPP nodes, looking to see if they are a closed group within the loop.
635 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
636 // The idea is that the phi-nest must boil down to only CastPP nodes
637 // with the same data. This implies that any path into the loop already
638 // includes such a CastPP, and so the original cast, whatever its input,
639 // must be covered by an equivalent cast, with an earlier control input.
640 ResourceMark rm;
641
642 // The loop entry input of the phi should be the unique dominating
643 // node for every Phi/CastPP in the loop.
644 Unique_Node_List closure;
645 closure.push(adr_phi->in(LoopNode::EntryControl));
646
647 // Add the phi node and the cast to the worklist.
648 Unique_Node_List worklist;
649 worklist.push(adr_phi);
650 if( cast != NULL ){
651 if( !cast->is_ConstraintCast() ) return false;
652 worklist.push(cast);
653 }
654
655 // Begin recursive walk of phi nodes.
656 while( worklist.size() ){
657 // Take a node off the worklist
658 Node *n = worklist.pop();
659 if( !closure.member(n) ){
660 // Add it to the closure.
661 closure.push(n);
662 // Make a sanity check to ensure we don't waste too much time here.
663 if( closure.size() > 20) return false;
664 // This node is OK if:
665 // - it is a cast of an identical value
666 // - or it is a phi node (then we add its inputs to the worklist)
667 // Otherwise, the node is not OK, and we presume the cast is not invariant
668 if( n->is_ConstraintCast() ){
669 worklist.push(n->in(1));
670 } else if( n->is_Phi() ) {
671 for( uint i = 1; i < n->req(); i++ ) {
672 worklist.push(n->in(i));
673 }
674 } else {
675 return false;
676 }
677 }
678 }
679
680 // Quit when the worklist is empty, and we've found no offending nodes.
681 return true;
682 }
683
684 //------------------------------Ideal_DU_postCCP-------------------------------
685 // Find any cast-away of null-ness and keep its control. Null cast-aways are
686 // going away in this pass and we need to make this memory op depend on the
687 // gating null check.
688 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
689 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
690 }
691
692 // I tried to leave the CastPP's in. This makes the graph more accurate in
693 // some sense; we get to keep around the knowledge that an oop is not-null
694 // after some test. Alas, the CastPP's interfere with GVN (some values are
695 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
696 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
697 // some of the more trivial cases in the optimizer. Removing more useless
698 // Phi's started allowing Loads to illegally float above null checks. I gave
699 // up on this approach. CNC 10/20/2000
700 // This static method may be called not from MemNode (EncodePNode calls it).
701 // Only the control edge of the node 'n' might be updated.
702 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
703 Node *skipped_cast = NULL;
704 // Need a null check? Regular static accesses do not because they are
705 // from constant addresses. Array ops are gated by the range check (which
706 // always includes a NULL check). Just check field ops.
707 if( n->in(MemNode::Control) == NULL ) {
708 // Scan upwards for the highest location we can place this memory op.
709 while( true ) {
710 switch( adr->Opcode() ) {
711
712 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
713 adr = adr->in(AddPNode::Base);
714 continue;
715
716 case Op_DecodeN: // No change to NULL-ness, so peek thru
717 adr = adr->in(1);
718 continue;
719
720 case Op_CastPP:
721 // If the CastPP is useless, just peek on through it.
722 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
723 // Remember the cast that we've peeked though. If we peek
724 // through more than one, then we end up remembering the highest
725 // one, that is, if in a loop, the one closest to the top.
726 skipped_cast = adr;
727 adr = adr->in(1);
728 continue;
729 }
730 // CastPP is going away in this pass! We need this memory op to be
731 // control-dependent on the test that is guarding the CastPP.
732 ccp->hash_delete(n);
733 n->set_req(MemNode::Control, adr->in(0));
734 ccp->hash_insert(n);
735 return n;
736
737 case Op_Phi:
738 // Attempt to float above a Phi to some dominating point.
739 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
740 // If we've already peeked through a Cast (which could have set the
741 // control), we can't float above a Phi, because the skipped Cast
742 // may not be loop invariant.
743 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
744 adr = adr->in(1);
745 continue;
746 }
747 }
748
749 // Intentional fallthrough!
750
751 // No obvious dominating point. The mem op is pinned below the Phi
752 // by the Phi itself. If the Phi goes away (no true value is merged)
753 // then the mem op can float, but not indefinitely. It must be pinned
754 // behind the controls leading to the Phi.
755 case Op_CheckCastPP:
756 // These usually stick around to change address type, however a
757 // useless one can be elided and we still need to pick up a control edge
758 if (adr->in(0) == NULL) {
759 // This CheckCastPP node has NO control and is likely useless. But we
760 // need check further up the ancestor chain for a control input to keep
761 // the node in place. 4959717.
762 skipped_cast = adr;
763 adr = adr->in(1);
764 continue;
765 }
766 ccp->hash_delete(n);
767 n->set_req(MemNode::Control, adr->in(0));
768 ccp->hash_insert(n);
769 return n;
770
771 // List of "safe" opcodes; those that implicitly block the memory
772 // op below any null check.
773 case Op_CastX2P: // no null checks on native pointers
774 case Op_Parm: // 'this' pointer is not null
775 case Op_LoadP: // Loading from within a klass
776 case Op_LoadN: // Loading from within a klass
777 case Op_LoadKlass: // Loading from within a klass
778 case Op_LoadNKlass: // Loading from within a klass
779 case Op_ConP: // Loading from a klass
780 case Op_ConN: // Loading from a klass
781 case Op_CreateEx: // Sucking up the guts of an exception oop
782 case Op_Con: // Reading from TLS
783 case Op_CMoveP: // CMoveP is pinned
784 case Op_CMoveN: // CMoveN is pinned
785 break; // No progress
786
787 case Op_Proj: // Direct call to an allocation routine
788 case Op_SCMemProj: // Memory state from store conditional ops
789 #ifdef ASSERT
790 {
791 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
792 const Node* call = adr->in(0);
793 if (call->is_CallJava()) {
794 const CallJavaNode* call_java = call->as_CallJava();
795 const TypeTuple *r = call_java->tf()->range();
796 assert(r->cnt() > TypeFunc::Parms, "must return value");
797 const Type* ret_type = r->field_at(TypeFunc::Parms);
798 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
799 // We further presume that this is one of
800 // new_instance_Java, new_array_Java, or
801 // the like, but do not assert for this.
802 } else if (call->is_Allocate()) {
803 // similar case to new_instance_Java, etc.
804 } else if (!call->is_CallLeaf()) {
805 // Projections from fetch_oop (OSR) are allowed as well.
806 ShouldNotReachHere();
807 }
808 }
809 #endif
810 break;
811 default:
812 ShouldNotReachHere();
813 }
814 break;
815 }
816 }
817
818 return NULL; // No progress
819 }
820
821
822 //=============================================================================
823 uint LoadNode::size_of() const { return sizeof(*this); }
824 uint LoadNode::cmp( const Node &n ) const
825 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
826 const Type *LoadNode::bottom_type() const { return _type; }
827 uint LoadNode::ideal_reg() const {
828 return Matcher::base2reg[_type->base()];
829 }
830
831 #ifndef PRODUCT
832 void LoadNode::dump_spec(outputStream *st) const {
833 MemNode::dump_spec(st);
834 if( !Verbose && !WizardMode ) {
835 // standard dump does this in Verbose and WizardMode
836 st->print(" #"); _type->dump_on(st);
837 }
838 }
839 #endif
840
841 #ifdef ASSERT
842 //----------------------------is_immutable_value-------------------------------
843 // Helper function to allow a raw load without control edge for some cases
844 bool LoadNode::is_immutable_value(Node* adr) {
845 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
846 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
847 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
848 in_bytes(JavaThread::osthread_offset())));
849 }
850 #endif
851
852 //----------------------------LoadNode::make-----------------------------------
853 // Polymorphic factory method:
854 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
855 Compile* C = gvn.C;
856
857 // sanity check the alias category against the created node type
858 assert(!(adr_type->isa_oopptr() &&
859 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
860 "use LoadKlassNode instead");
861 assert(!(adr_type->isa_aryptr() &&
862 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
863 "use LoadRangeNode instead");
864 // Check control edge of raw loads
865 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
866 // oop will be recorded in oop map if load crosses safepoint
867 rt->isa_oopptr() || is_immutable_value(adr),
868 "raw memory operations should have control edge");
869 switch (bt) {
870 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
871 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
872 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
873 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
874 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
875 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
876 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
877 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
878 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
879 case T_OBJECT:
880 #ifdef _LP64
881 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
882 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
883 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
884 } else
885 #endif
886 {
887 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
888 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
889 }
890 }
891 ShouldNotReachHere();
892 return (LoadNode*)NULL;
893 }
894
895 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
896 bool require_atomic = true;
897 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
898 }
899
900
901
902
903 //------------------------------hash-------------------------------------------
904 uint LoadNode::hash() const {
905 // unroll addition of interesting fields
906 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
907 }
908
909 //---------------------------can_see_stored_value------------------------------
910 // This routine exists to make sure this set of tests is done the same
911 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
912 // will change the graph shape in a way which makes memory alive twice at the
913 // same time (uses the Oracle model of aliasing), then some
914 // LoadXNode::Identity will fold things back to the equivalence-class model
915 // of aliasing.
916 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
917 Node* ld_adr = in(MemNode::Address);
918
919 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
920 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
921 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
922 atp->field() != NULL && !atp->field()->is_volatile()) {
923 uint alias_idx = atp->index();
924 bool final = atp->field()->is_final();
925 Node* result = NULL;
926 Node* current = st;
927 // Skip through chains of MemBarNodes checking the MergeMems for
928 // new states for the slice of this load. Stop once any other
929 // kind of node is encountered. Loads from final memory can skip
930 // through any kind of MemBar but normal loads shouldn't skip
931 // through MemBarAcquire since the could allow them to move out of
932 // a synchronized region.
933 while (current->is_Proj()) {
934 int opc = current->in(0)->Opcode();
935 if ((final && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock)) ||
936 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder ||
937 opc == Op_MemBarReleaseLock) {
938 Node* mem = current->in(0)->in(TypeFunc::Memory);
939 if (mem->is_MergeMem()) {
940 MergeMemNode* merge = mem->as_MergeMem();
941 Node* new_st = merge->memory_at(alias_idx);
942 if (new_st == merge->base_memory()) {
943 // Keep searching
944 current = merge->base_memory();
945 continue;
946 }
947 // Save the new memory state for the slice and fall through
948 // to exit.
949 result = new_st;
950 }
951 }
952 break;
953 }
954 if (result != NULL) {
955 st = result;
956 }
957 }
958
959
960 // Loop around twice in the case Load -> Initialize -> Store.
961 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
962 for (int trip = 0; trip <= 1; trip++) {
963
964 if (st->is_Store()) {
965 Node* st_adr = st->in(MemNode::Address);
966 if (!phase->eqv(st_adr, ld_adr)) {
967 // Try harder before giving up... Match raw and non-raw pointers.
968 intptr_t st_off = 0;
969 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
970 if (alloc == NULL) return NULL;
971 intptr_t ld_off = 0;
972 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
973 if (alloc != allo2) return NULL;
974 if (ld_off != st_off) return NULL;
975 // At this point we have proven something like this setup:
976 // A = Allocate(...)
977 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
978 // S = StoreQ(, AddP(, A.Parm , #Off), V)
979 // (Actually, we haven't yet proven the Q's are the same.)
980 // In other words, we are loading from a casted version of
981 // the same pointer-and-offset that we stored to.
982 // Thus, we are able to replace L by V.
983 }
984 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
985 if (store_Opcode() != st->Opcode())
986 return NULL;
987 return st->in(MemNode::ValueIn);
988 }
989
990 intptr_t offset = 0; // scratch
991
992 // A load from a freshly-created object always returns zero.
993 // (This can happen after LoadNode::Ideal resets the load's memory input
994 // to find_captured_store, which returned InitializeNode::zero_memory.)
995 if (st->is_Proj() && st->in(0)->is_Allocate() &&
996 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
997 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
998 // return a zero value for the load's basic type
999 // (This is one of the few places where a generic PhaseTransform
1000 // can create new nodes. Think of it as lazily manifesting
1001 // virtually pre-existing constants.)
1002 return phase->zerocon(memory_type());
1003 }
1004
1005 // A load from an initialization barrier can match a captured store.
1006 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1007 InitializeNode* init = st->in(0)->as_Initialize();
1008 AllocateNode* alloc = init->allocation();
1009 if (alloc != NULL &&
1010 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1011 // examine a captured store value
1012 st = init->find_captured_store(offset, memory_size(), phase);
1013 if (st != NULL)
1014 continue; // take one more trip around
1015 }
1016 }
1017
1018 break;
1019 }
1020
1021 return NULL;
1022 }
1023
1024 //----------------------is_instance_field_load_with_local_phi------------------
1025 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1026 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1027 in(MemNode::Address)->is_AddP() ) {
1028 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1029 // Only instances.
1030 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1031 t_oop->offset() != Type::OffsetBot &&
1032 t_oop->offset() != Type::OffsetTop) {
1033 return true;
1034 }
1035 }
1036 return false;
1037 }
1038
1039 //------------------------------Identity---------------------------------------
1040 // Loads are identity if previous store is to same address
1041 Node *LoadNode::Identity( PhaseTransform *phase ) {
1042 // If the previous store-maker is the right kind of Store, and the store is
1043 // to the same address, then we are equal to the value stored.
1044 Node* mem = in(MemNode::Memory);
1045 Node* value = can_see_stored_value(mem, phase);
1046 if( value ) {
1047 // byte, short & char stores truncate naturally.
1048 // A load has to load the truncated value which requires
1049 // some sort of masking operation and that requires an
1050 // Ideal call instead of an Identity call.
1051 if (memory_size() < BytesPerInt) {
1052 // If the input to the store does not fit with the load's result type,
1053 // it must be truncated via an Ideal call.
1054 if (!phase->type(value)->higher_equal(phase->type(this)))
1055 return this;
1056 }
1057 // (This works even when value is a Con, but LoadNode::Value
1058 // usually runs first, producing the singleton type of the Con.)
1059 return value;
1060 }
1061
1062 // Search for an existing data phi which was generated before for the same
1063 // instance's field to avoid infinite generation of phis in a loop.
1064 Node *region = mem->in(0);
1065 if (is_instance_field_load_with_local_phi(region)) {
1066 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1067 int this_index = phase->C->get_alias_index(addr_t);
1068 int this_offset = addr_t->offset();
1069 int this_id = addr_t->is_oopptr()->instance_id();
1070 const Type* this_type = bottom_type();
1071 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1072 Node* phi = region->fast_out(i);
1073 if (phi->is_Phi() && phi != mem &&
1074 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1075 return phi;
1076 }
1077 }
1078 }
1079
1080 return this;
1081 }
1082
1083
1084 // Returns true if the AliasType refers to the field that holds the
1085 // cached box array. Currently only handles the IntegerCache case.
1086 static bool is_autobox_cache(Compile::AliasType* atp) {
1087 if (atp != NULL && atp->field() != NULL) {
1088 ciField* field = atp->field();
1089 ciSymbol* klass = field->holder()->name();
1090 if (field->name() == ciSymbol::cache_field_name() &&
1091 field->holder()->uses_default_loader() &&
1092 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1093 return true;
1094 }
1095 }
1096 return false;
1097 }
1098
1099 // Fetch the base value in the autobox array
1100 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1101 if (atp != NULL && atp->field() != NULL) {
1102 ciField* field = atp->field();
1103 ciSymbol* klass = field->holder()->name();
1104 if (field->name() == ciSymbol::cache_field_name() &&
1105 field->holder()->uses_default_loader() &&
1106 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1107 assert(field->is_constant(), "what?");
1108 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1109 // Fetch the box object at the base of the array and get its value
1110 ciInstance* box = array->obj_at(0)->as_instance();
1111 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1112 if (ik->nof_nonstatic_fields() == 1) {
1113 // This should be true nonstatic_field_at requires calling
1114 // nof_nonstatic_fields so check it anyway
1115 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1116 cache_offset = c.as_int();
1117 }
1118 return true;
1119 }
1120 }
1121 return false;
1122 }
1123
1124 // Returns true if the AliasType refers to the value field of an
1125 // autobox object. Currently only handles Integer.
1126 static bool is_autobox_object(Compile::AliasType* atp) {
1127 if (atp != NULL && atp->field() != NULL) {
1128 ciField* field = atp->field();
1129 ciSymbol* klass = field->holder()->name();
1130 if (field->name() == ciSymbol::value_name() &&
1131 field->holder()->uses_default_loader() &&
1132 klass == ciSymbol::java_lang_Integer()) {
1133 return true;
1134 }
1135 }
1136 return false;
1137 }
1138
1139
1140 // We're loading from an object which has autobox behaviour.
1141 // If this object is result of a valueOf call we'll have a phi
1142 // merging a newly allocated object and a load from the cache.
1143 // We want to replace this load with the original incoming
1144 // argument to the valueOf call.
1145 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1146 Node* base = in(Address)->in(AddPNode::Base);
1147 if (base->is_Phi() && base->req() == 3) {
1148 AllocateNode* allocation = NULL;
1149 int allocation_index = -1;
1150 int load_index = -1;
1151 for (uint i = 1; i < base->req(); i++) {
1152 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1153 if (allocation != NULL) {
1154 allocation_index = i;
1155 load_index = 3 - allocation_index;
1156 break;
1157 }
1158 }
1159 bool has_load = ( allocation != NULL &&
1160 (base->in(load_index)->is_Load() ||
1161 base->in(load_index)->is_DecodeN() &&
1162 base->in(load_index)->in(1)->is_Load()) );
1163 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1164 // Push the loads from the phi that comes from valueOf up
1165 // through it to allow elimination of the loads and the recovery
1166 // of the original value.
1167 Node* mem_phi = in(Memory);
1168 Node* offset = in(Address)->in(AddPNode::Offset);
1169 Node* region = base->in(0);
1170
1171 Node* in1 = clone();
1172 Node* in1_addr = in1->in(Address)->clone();
1173 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1174 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1175 in1_addr->set_req(AddPNode::Offset, offset);
1176 in1->set_req(0, region->in(allocation_index));
1177 in1->set_req(Address, in1_addr);
1178 in1->set_req(Memory, mem_phi->in(allocation_index));
1179
1180 Node* in2 = clone();
1181 Node* in2_addr = in2->in(Address)->clone();
1182 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1183 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1184 in2_addr->set_req(AddPNode::Offset, offset);
1185 in2->set_req(0, region->in(load_index));
1186 in2->set_req(Address, in2_addr);
1187 in2->set_req(Memory, mem_phi->in(load_index));
1188
1189 in1_addr = phase->transform(in1_addr);
1190 in1 = phase->transform(in1);
1191 in2_addr = phase->transform(in2_addr);
1192 in2 = phase->transform(in2);
1193
1194 PhiNode* result = PhiNode::make_blank(region, this);
1195 result->set_req(allocation_index, in1);
1196 result->set_req(load_index, in2);
1197 return result;
1198 }
1199 } else if (base->is_Load() ||
1200 base->is_DecodeN() && base->in(1)->is_Load()) {
1201 if (base->is_DecodeN()) {
1202 // Get LoadN node which loads cached Integer object
1203 base = base->in(1);
1204 }
1205 // Eliminate the load of Integer.value for integers from the cache
1206 // array by deriving the value from the index into the array.
1207 // Capture the offset of the load and then reverse the computation.
1208 Node* load_base = base->in(Address)->in(AddPNode::Base);
1209 if (load_base->is_DecodeN()) {
1210 // Get LoadN node which loads IntegerCache.cache field
1211 load_base = load_base->in(1);
1212 }
1213 if (load_base != NULL) {
1214 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1215 intptr_t cache_offset;
1216 int shift = -1;
1217 Node* cache = NULL;
1218 if (is_autobox_cache(atp)) {
1219 shift = exact_log2(type2aelembytes(T_OBJECT));
1220 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1221 }
1222 if (cache != NULL && base->in(Address)->is_AddP()) {
1223 Node* elements[4];
1224 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1225 int cache_low;
1226 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1227 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1228 // Add up all the offsets making of the address of the load
1229 Node* result = elements[0];
1230 for (int i = 1; i < count; i++) {
1231 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1232 }
1233 // Remove the constant offset from the address and then
1234 // remove the scaling of the offset to recover the original index.
1235 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1236 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1237 // Peel the shift off directly but wrap it in a dummy node
1238 // since Ideal can't return existing nodes
1239 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1240 } else {
1241 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1242 }
1243 #ifdef _LP64
1244 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1245 #endif
1246 return result;
1247 }
1248 }
1249 }
1250 }
1251 return NULL;
1252 }
1253
1254 //------------------------------split_through_phi------------------------------
1255 // Split instance field load through Phi.
1256 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1257 Node* mem = in(MemNode::Memory);
1258 Node* address = in(MemNode::Address);
1259 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1260 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1261
1262 assert(mem->is_Phi() && (t_oop != NULL) &&
1263 t_oop->is_known_instance_field(), "invalide conditions");
1264
1265 Node *region = mem->in(0);
1266 if (region == NULL) {
1267 return NULL; // Wait stable graph
1268 }
1269 uint cnt = mem->req();
1270 for (uint i = 1; i < cnt; i++) {
1271 Node* rc = region->in(i);
1272 if (rc == NULL || phase->type(rc) == Type::TOP)
1273 return NULL; // Wait stable graph
1274 Node *in = mem->in(i);
1275 if (in == NULL) {
1276 return NULL; // Wait stable graph
1277 }
1278 }
1279 // Check for loop invariant.
1280 if (cnt == 3) {
1281 for (uint i = 1; i < cnt; i++) {
1282 Node *in = mem->in(i);
1283 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1284 if (m == mem) {
1285 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1286 return this;
1287 }
1288 }
1289 }
1290 // Split through Phi (see original code in loopopts.cpp).
1291 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1292
1293 // Do nothing here if Identity will find a value
1294 // (to avoid infinite chain of value phis generation).
1295 if (!phase->eqv(this, this->Identity(phase)))
1296 return NULL;
1297
1298 // Skip the split if the region dominates some control edge of the address.
1299 if (!MemNode::all_controls_dominate(address, region))
1300 return NULL;
1301
1302 const Type* this_type = this->bottom_type();
1303 int this_index = phase->C->get_alias_index(addr_t);
1304 int this_offset = addr_t->offset();
1305 int this_iid = addr_t->is_oopptr()->instance_id();
1306 PhaseIterGVN *igvn = phase->is_IterGVN();
1307 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1308 for (uint i = 1; i < region->req(); i++) {
1309 Node *x;
1310 Node* the_clone = NULL;
1311 if (region->in(i) == phase->C->top()) {
1312 x = phase->C->top(); // Dead path? Use a dead data op
1313 } else {
1314 x = this->clone(); // Else clone up the data op
1315 the_clone = x; // Remember for possible deletion.
1316 // Alter data node to use pre-phi inputs
1317 if (this->in(0) == region) {
1318 x->set_req(0, region->in(i));
1319 } else {
1320 x->set_req(0, NULL);
1321 }
1322 for (uint j = 1; j < this->req(); j++) {
1323 Node *in = this->in(j);
1324 if (in->is_Phi() && in->in(0) == region)
1325 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
1326 }
1327 }
1328 // Check for a 'win' on some paths
1329 const Type *t = x->Value(igvn);
1330
1331 bool singleton = t->singleton();
1332
1333 // See comments in PhaseIdealLoop::split_thru_phi().
1334 if (singleton && t == Type::TOP) {
1335 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1336 }
1337
1338 if (singleton) {
1339 x = igvn->makecon(t);
1340 } else {
1341 // We now call Identity to try to simplify the cloned node.
1342 // Note that some Identity methods call phase->type(this).
1343 // Make sure that the type array is big enough for
1344 // our new node, even though we may throw the node away.
1345 // (This tweaking with igvn only works because x is a new node.)
1346 igvn->set_type(x, t);
1347 // If x is a TypeNode, capture any more-precise type permanently into Node
1348 // otherwise it will be not updated during igvn->transform since
1349 // igvn->type(x) is set to x->Value() already.
1350 x->raise_bottom_type(t);
1351 Node *y = x->Identity(igvn);
1352 if (y != x) {
1353 x = y;
1354 } else {
1355 y = igvn->hash_find(x);
1356 if (y) {
1357 x = y;
1358 } else {
1359 // Else x is a new node we are keeping
1360 // We do not need register_new_node_with_optimizer
1361 // because set_type has already been called.
1362 igvn->_worklist.push(x);
1363 }
1364 }
1365 }
1366 if (x != the_clone && the_clone != NULL)
1367 igvn->remove_dead_node(the_clone);
1368 phi->set_req(i, x);
1369 }
1370 // Record Phi
1371 igvn->register_new_node_with_optimizer(phi);
1372 return phi;
1373 }
1374
1375 //------------------------------Ideal------------------------------------------
1376 // If the load is from Field memory and the pointer is non-null, we can
1377 // zero out the control input.
1378 // If the offset is constant and the base is an object allocation,
1379 // try to hook me up to the exact initializing store.
1380 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1381 Node* p = MemNode::Ideal_common(phase, can_reshape);
1382 if (p) return (p == NodeSentinel) ? NULL : p;
1383
1384 Node* ctrl = in(MemNode::Control);
1385 Node* address = in(MemNode::Address);
1386
1387 // Skip up past a SafePoint control. Cannot do this for Stores because
1388 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1389 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1390 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1391 ctrl = ctrl->in(0);
1392 set_req(MemNode::Control,ctrl);
1393 }
1394
1395 intptr_t ignore = 0;
1396 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1397 if (base != NULL
1398 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1399 // Check for useless control edge in some common special cases
1400 if (in(MemNode::Control) != NULL
1401 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1402 && all_controls_dominate(base, phase->C->start())) {
1403 // A method-invariant, non-null address (constant or 'this' argument).
1404 set_req(MemNode::Control, NULL);
1405 }
1406
1407 if (EliminateAutoBox && can_reshape) {
1408 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1409 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1410 if (is_autobox_object(atp)) {
1411 Node* result = eliminate_autobox(phase);
1412 if (result != NULL) return result;
1413 }
1414 }
1415 }
1416
1417 Node* mem = in(MemNode::Memory);
1418 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1419
1420 if (addr_t != NULL) {
1421 // try to optimize our memory input
1422 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1423 if (opt_mem != mem) {
1424 set_req(MemNode::Memory, opt_mem);
1425 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1426 return this;
1427 }
1428 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1429 if (can_reshape && opt_mem->is_Phi() &&
1430 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1431 PhaseIterGVN *igvn = phase->is_IterGVN();
1432 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1433 // Delay this transformation until memory Phi is processed.
1434 phase->is_IterGVN()->_worklist.push(this);
1435 return NULL;
1436 }
1437 // Split instance field load through Phi.
1438 Node* result = split_through_phi(phase);
1439 if (result != NULL) return result;
1440 }
1441 }
1442
1443 // Check for prior store with a different base or offset; make Load
1444 // independent. Skip through any number of them. Bail out if the stores
1445 // are in an endless dead cycle and report no progress. This is a key
1446 // transform for Reflection. However, if after skipping through the Stores
1447 // we can't then fold up against a prior store do NOT do the transform as
1448 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1449 // array memory alive twice: once for the hoisted Load and again after the
1450 // bypassed Store. This situation only works if EVERYBODY who does
1451 // anti-dependence work knows how to bypass. I.e. we need all
1452 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1453 // the alias index stuff. So instead, peek through Stores and IFF we can
1454 // fold up, do so.
1455 Node* prev_mem = find_previous_store(phase);
1456 // Steps (a), (b): Walk past independent stores to find an exact match.
1457 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1458 // (c) See if we can fold up on the spot, but don't fold up here.
1459 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1460 // just return a prior value, which is done by Identity calls.
1461 if (can_see_stored_value(prev_mem, phase)) {
1462 // Make ready for step (d):
1463 set_req(MemNode::Memory, prev_mem);
1464 return this;
1465 }
1466 }
1467
1468 return NULL; // No further progress
1469 }
1470
1471 // Helper to recognize certain Klass fields which are invariant across
1472 // some group of array types (e.g., int[] or all T[] where T < Object).
1473 const Type*
1474 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1475 ciKlass* klass) const {
1476 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1477 // The field is Klass::_modifier_flags. Return its (constant) value.
1478 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1479 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1480 return TypeInt::make(klass->modifier_flags());
1481 }
1482 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1483 // The field is Klass::_access_flags. Return its (constant) value.
1484 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1485 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1486 return TypeInt::make(klass->access_flags());
1487 }
1488 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1489 // The field is Klass::_layout_helper. Return its constant value if known.
1490 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1491 return TypeInt::make(klass->layout_helper());
1492 }
1493
1494 // No match.
1495 return NULL;
1496 }
1497
1498 //------------------------------Value-----------------------------------------
1499 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1500 // Either input is TOP ==> the result is TOP
1501 Node* mem = in(MemNode::Memory);
1502 const Type *t1 = phase->type(mem);
1503 if (t1 == Type::TOP) return Type::TOP;
1504 Node* adr = in(MemNode::Address);
1505 const TypePtr* tp = phase->type(adr)->isa_ptr();
1506 if (tp == NULL || tp->empty()) return Type::TOP;
1507 int off = tp->offset();
1508 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1509 Compile* C = phase->C;
1510
1511 // Try to guess loaded type from pointer type
1512 if (tp->base() == Type::AryPtr) {
1513 const Type *t = tp->is_aryptr()->elem();
1514 // Don't do this for integer types. There is only potential profit if
1515 // the element type t is lower than _type; that is, for int types, if _type is
1516 // more restrictive than t. This only happens here if one is short and the other
1517 // char (both 16 bits), and in those cases we've made an intentional decision
1518 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1519 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1520 //
1521 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1522 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1523 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1524 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1525 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1526 // In fact, that could have been the original type of p1, and p1 could have
1527 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1528 // expression (LShiftL quux 3) independently optimized to the constant 8.
1529 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1530 && (_type->isa_vect() == NULL)
1531 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1532 // t might actually be lower than _type, if _type is a unique
1533 // concrete subclass of abstract class t.
1534 // Make sure the reference is not into the header, by comparing
1535 // the offset against the offset of the start of the array's data.
1536 // Different array types begin at slightly different offsets (12 vs. 16).
1537 // We choose T_BYTE as an example base type that is least restrictive
1538 // as to alignment, which will therefore produce the smallest
1539 // possible base offset.
1540 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1541 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1542 const Type* jt = t->join(_type);
1543 // In any case, do not allow the join, per se, to empty out the type.
1544 if (jt->empty() && !t->empty()) {
1545 // This can happen if a interface-typed array narrows to a class type.
1546 jt = _type;
1547 }
1548
1549 if (EliminateAutoBox && adr->is_AddP()) {
1550 // The pointers in the autobox arrays are always non-null
1551 Node* base = adr->in(AddPNode::Base);
1552 if (base != NULL &&
1553 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1554 Compile::AliasType* atp = C->alias_type(base->adr_type());
1555 if (is_autobox_cache(atp)) {
1556 return jt->join(TypePtr::NOTNULL)->is_ptr();
1557 }
1558 }
1559 }
1560 return jt;
1561 }
1562 }
1563 } else if (tp->base() == Type::InstPtr) {
1564 ciEnv* env = C->env();
1565 const TypeInstPtr* tinst = tp->is_instptr();
1566 ciKlass* klass = tinst->klass();
1567 assert( off != Type::OffsetBot ||
1568 // arrays can be cast to Objects
1569 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1570 // unsafe field access may not have a constant offset
1571 C->has_unsafe_access(),
1572 "Field accesses must be precise" );
1573 // For oop loads, we expect the _type to be precise
1574 if (klass == env->String_klass() &&
1575 adr->is_AddP() && off != Type::OffsetBot) {
1576 // For constant Strings treat the final fields as compile time constants.
1577 Node* base = adr->in(AddPNode::Base);
1578 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1579 if (t != NULL && t->singleton()) {
1580 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1581 if (field != NULL && field->is_final()) {
1582 ciObject* string = t->const_oop();
1583 ciConstant constant = string->as_instance()->field_value(field);
1584 if (constant.basic_type() == T_INT) {
1585 return TypeInt::make(constant.as_int());
1586 } else if (constant.basic_type() == T_ARRAY) {
1587 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1588 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1589 } else {
1590 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1591 }
1592 }
1593 }
1594 }
1595 }
1596 // Optimizations for constant objects
1597 ciObject* const_oop = tinst->const_oop();
1598 if (const_oop != NULL) {
1599 // For constant CallSites treat the target field as a compile time constant.
1600 if (const_oop->is_call_site()) {
1601 ciCallSite* call_site = const_oop->as_call_site();
1602 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1603 if (field != NULL && field->is_call_site_target()) {
1604 ciMethodHandle* target = call_site->get_target();
1605 if (target != NULL) { // just in case
1606 ciConstant constant(T_OBJECT, target);
1607 const Type* t;
1608 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1609 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1610 } else {
1611 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1612 }
1613 // Add a dependence for invalidation of the optimization.
1614 if (!call_site->is_constant_call_site()) {
1615 C->dependencies()->assert_call_site_target_value(call_site, target);
1616 }
1617 return t;
1618 }
1619 }
1620 }
1621 }
1622 } else if (tp->base() == Type::KlassPtr) {
1623 assert( off != Type::OffsetBot ||
1624 // arrays can be cast to Objects
1625 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1626 // also allow array-loading from the primary supertype
1627 // array during subtype checks
1628 Opcode() == Op_LoadKlass,
1629 "Field accesses must be precise" );
1630 // For klass/static loads, we expect the _type to be precise
1631 }
1632
1633 const TypeKlassPtr *tkls = tp->isa_klassptr();
1634 if (tkls != NULL && !StressReflectiveCode) {
1635 ciKlass* klass = tkls->klass();
1636 if (klass->is_loaded() && tkls->klass_is_exact()) {
1637 // We are loading a field from a Klass metaobject whose identity
1638 // is known at compile time (the type is "exact" or "precise").
1639 // Check for fields we know are maintained as constants by the VM.
1640 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1641 // The field is Klass::_super_check_offset. Return its (constant) value.
1642 // (Folds up type checking code.)
1643 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1644 return TypeInt::make(klass->super_check_offset());
1645 }
1646 // Compute index into primary_supers array
1647 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(klassOop);
1648 // Check for overflowing; use unsigned compare to handle the negative case.
1649 if( depth < ciKlass::primary_super_limit() ) {
1650 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1651 // (Folds up type checking code.)
1652 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1653 ciKlass *ss = klass->super_of_depth(depth);
1654 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1655 }
1656 const Type* aift = load_array_final_field(tkls, klass);
1657 if (aift != NULL) return aift;
1658 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset())
1659 && klass->is_array_klass()) {
1660 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1661 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1662 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1663 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1664 }
1665 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1666 // The field is Klass::_java_mirror. Return its (constant) value.
1667 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1668 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1669 return TypeInstPtr::make(klass->java_mirror());
1670 }
1671 }
1672
1673 // We can still check if we are loading from the primary_supers array at a
1674 // shallow enough depth. Even though the klass is not exact, entries less
1675 // than or equal to its super depth are correct.
1676 if (klass->is_loaded() ) {
1677 ciType *inner = klass->klass();
1678 while( inner->is_obj_array_klass() )
1679 inner = inner->as_obj_array_klass()->base_element_type();
1680 if( inner->is_instance_klass() &&
1681 !inner->as_instance_klass()->flags().is_interface() ) {
1682 // Compute index into primary_supers array
1683 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(klassOop);
1684 // Check for overflowing; use unsigned compare to handle the negative case.
1685 if( depth < ciKlass::primary_super_limit() &&
1686 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1687 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1688 // (Folds up type checking code.)
1689 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1690 ciKlass *ss = klass->super_of_depth(depth);
1691 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1692 }
1693 }
1694 }
1695
1696 // If the type is enough to determine that the thing is not an array,
1697 // we can give the layout_helper a positive interval type.
1698 // This will help short-circuit some reflective code.
1699 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1700 && !klass->is_array_klass() // not directly typed as an array
1701 && !klass->is_interface() // specifically not Serializable & Cloneable
1702 && !klass->is_java_lang_Object() // not the supertype of all T[]
1703 ) {
1704 // Note: When interfaces are reliable, we can narrow the interface
1705 // test to (klass != Serializable && klass != Cloneable).
1706 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1707 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1708 // The key property of this type is that it folds up tests
1709 // for array-ness, since it proves that the layout_helper is positive.
1710 // Thus, a generic value like the basic object layout helper works fine.
1711 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1712 }
1713 }
1714
1715 // If we are loading from a freshly-allocated object, produce a zero,
1716 // if the load is provably beyond the header of the object.
1717 // (Also allow a variable load from a fresh array to produce zero.)
1718 const TypeOopPtr *tinst = tp->isa_oopptr();
1719 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1720 if (ReduceFieldZeroing || is_instance) {
1721 Node* value = can_see_stored_value(mem,phase);
1722 if (value != NULL && value->is_Con()) {
1723 assert(value->bottom_type()->higher_equal(_type),"sanity");
1724 return value->bottom_type();
1725 }
1726 }
1727
1728 if (is_instance) {
1729 // If we have an instance type and our memory input is the
1730 // programs's initial memory state, there is no matching store,
1731 // so just return a zero of the appropriate type
1732 Node *mem = in(MemNode::Memory);
1733 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1734 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1735 return Type::get_zero_type(_type->basic_type());
1736 }
1737 }
1738 return _type;
1739 }
1740
1741 //------------------------------match_edge-------------------------------------
1742 // Do we Match on this edge index or not? Match only the address.
1743 uint LoadNode::match_edge(uint idx) const {
1744 return idx == MemNode::Address;
1745 }
1746
1747 //--------------------------LoadBNode::Ideal--------------------------------------
1748 //
1749 // If the previous store is to the same address as this load,
1750 // and the value stored was larger than a byte, replace this load
1751 // with the value stored truncated to a byte. If no truncation is
1752 // needed, the replacement is done in LoadNode::Identity().
1753 //
1754 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1755 Node* mem = in(MemNode::Memory);
1756 Node* value = can_see_stored_value(mem,phase);
1757 if( value && !phase->type(value)->higher_equal( _type ) ) {
1758 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1759 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1760 }
1761 // Identity call will handle the case where truncation is not needed.
1762 return LoadNode::Ideal(phase, can_reshape);
1763 }
1764
1765 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1766 Node* mem = in(MemNode::Memory);
1767 Node* value = can_see_stored_value(mem,phase);
1768 if (value != NULL && value->is_Con() &&
1769 !value->bottom_type()->higher_equal(_type)) {
1770 // If the input to the store does not fit with the load's result type,
1771 // it must be truncated. We can't delay until Ideal call since
1772 // a singleton Value is needed for split_thru_phi optimization.
1773 int con = value->get_int();
1774 return TypeInt::make((con << 24) >> 24);
1775 }
1776 return LoadNode::Value(phase);
1777 }
1778
1779 //--------------------------LoadUBNode::Ideal-------------------------------------
1780 //
1781 // If the previous store is to the same address as this load,
1782 // and the value stored was larger than a byte, replace this load
1783 // with the value stored truncated to a byte. If no truncation is
1784 // needed, the replacement is done in LoadNode::Identity().
1785 //
1786 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1787 Node* mem = in(MemNode::Memory);
1788 Node* value = can_see_stored_value(mem, phase);
1789 if (value && !phase->type(value)->higher_equal(_type))
1790 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1791 // Identity call will handle the case where truncation is not needed.
1792 return LoadNode::Ideal(phase, can_reshape);
1793 }
1794
1795 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1796 Node* mem = in(MemNode::Memory);
1797 Node* value = can_see_stored_value(mem,phase);
1798 if (value != NULL && value->is_Con() &&
1799 !value->bottom_type()->higher_equal(_type)) {
1800 // If the input to the store does not fit with the load's result type,
1801 // it must be truncated. We can't delay until Ideal call since
1802 // a singleton Value is needed for split_thru_phi optimization.
1803 int con = value->get_int();
1804 return TypeInt::make(con & 0xFF);
1805 }
1806 return LoadNode::Value(phase);
1807 }
1808
1809 //--------------------------LoadUSNode::Ideal-------------------------------------
1810 //
1811 // If the previous store is to the same address as this load,
1812 // and the value stored was larger than a char, replace this load
1813 // with the value stored truncated to a char. If no truncation is
1814 // needed, the replacement is done in LoadNode::Identity().
1815 //
1816 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1817 Node* mem = in(MemNode::Memory);
1818 Node* value = can_see_stored_value(mem,phase);
1819 if( value && !phase->type(value)->higher_equal( _type ) )
1820 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1821 // Identity call will handle the case where truncation is not needed.
1822 return LoadNode::Ideal(phase, can_reshape);
1823 }
1824
1825 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1826 Node* mem = in(MemNode::Memory);
1827 Node* value = can_see_stored_value(mem,phase);
1828 if (value != NULL && value->is_Con() &&
1829 !value->bottom_type()->higher_equal(_type)) {
1830 // If the input to the store does not fit with the load's result type,
1831 // it must be truncated. We can't delay until Ideal call since
1832 // a singleton Value is needed for split_thru_phi optimization.
1833 int con = value->get_int();
1834 return TypeInt::make(con & 0xFFFF);
1835 }
1836 return LoadNode::Value(phase);
1837 }
1838
1839 //--------------------------LoadSNode::Ideal--------------------------------------
1840 //
1841 // If the previous store is to the same address as this load,
1842 // and the value stored was larger than a short, replace this load
1843 // with the value stored truncated to a short. If no truncation is
1844 // needed, the replacement is done in LoadNode::Identity().
1845 //
1846 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1847 Node* mem = in(MemNode::Memory);
1848 Node* value = can_see_stored_value(mem,phase);
1849 if( value && !phase->type(value)->higher_equal( _type ) ) {
1850 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1851 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1852 }
1853 // Identity call will handle the case where truncation is not needed.
1854 return LoadNode::Ideal(phase, can_reshape);
1855 }
1856
1857 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1858 Node* mem = in(MemNode::Memory);
1859 Node* value = can_see_stored_value(mem,phase);
1860 if (value != NULL && value->is_Con() &&
1861 !value->bottom_type()->higher_equal(_type)) {
1862 // If the input to the store does not fit with the load's result type,
1863 // it must be truncated. We can't delay until Ideal call since
1864 // a singleton Value is needed for split_thru_phi optimization.
1865 int con = value->get_int();
1866 return TypeInt::make((con << 16) >> 16);
1867 }
1868 return LoadNode::Value(phase);
1869 }
1870
1871 //=============================================================================
1872 //----------------------------LoadKlassNode::make------------------------------
1873 // Polymorphic factory method:
1874 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1875 Compile* C = gvn.C;
1876 Node *ctl = NULL;
1877 // sanity check the alias category against the created node type
1878 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1879 assert(adr_type != NULL, "expecting TypeOopPtr");
1880 #ifdef _LP64
1881 if (adr_type->is_ptr_to_narrowoop()) {
1882 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1883 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1884 }
1885 #endif
1886 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1887 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1888 }
1889
1890 //------------------------------Value------------------------------------------
1891 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1892 return klass_value_common(phase);
1893 }
1894
1895 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1896 // Either input is TOP ==> the result is TOP
1897 const Type *t1 = phase->type( in(MemNode::Memory) );
1898 if (t1 == Type::TOP) return Type::TOP;
1899 Node *adr = in(MemNode::Address);
1900 const Type *t2 = phase->type( adr );
1901 if (t2 == Type::TOP) return Type::TOP;
1902 const TypePtr *tp = t2->is_ptr();
1903 if (TypePtr::above_centerline(tp->ptr()) ||
1904 tp->ptr() == TypePtr::Null) return Type::TOP;
1905
1906 // Return a more precise klass, if possible
1907 const TypeInstPtr *tinst = tp->isa_instptr();
1908 if (tinst != NULL) {
1909 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1910 int offset = tinst->offset();
1911 if (ik == phase->C->env()->Class_klass()
1912 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1913 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1914 // We are loading a special hidden field from a Class mirror object,
1915 // the field which points to the VM's Klass metaobject.
1916 ciType* t = tinst->java_mirror_type();
1917 // java_mirror_type returns non-null for compile-time Class constants.
1918 if (t != NULL) {
1919 // constant oop => constant klass
1920 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1921 return TypeKlassPtr::make(ciArrayKlass::make(t));
1922 }
1923 if (!t->is_klass()) {
1924 // a primitive Class (e.g., int.class) has NULL for a klass field
1925 return TypePtr::NULL_PTR;
1926 }
1927 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1928 return TypeKlassPtr::make(t->as_klass());
1929 }
1930 // non-constant mirror, so we can't tell what's going on
1931 }
1932 if( !ik->is_loaded() )
1933 return _type; // Bail out if not loaded
1934 if (offset == oopDesc::klass_offset_in_bytes()) {
1935 if (tinst->klass_is_exact()) {
1936 return TypeKlassPtr::make(ik);
1937 }
1938 // See if we can become precise: no subklasses and no interface
1939 // (Note: We need to support verified interfaces.)
1940 if (!ik->is_interface() && !ik->has_subklass()) {
1941 //assert(!UseExactTypes, "this code should be useless with exact types");
1942 // Add a dependence; if any subclass added we need to recompile
1943 if (!ik->is_final()) {
1944 // %%% should use stronger assert_unique_concrete_subtype instead
1945 phase->C->dependencies()->assert_leaf_type(ik);
1946 }
1947 // Return precise klass
1948 return TypeKlassPtr::make(ik);
1949 }
1950
1951 // Return root of possible klass
1952 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1953 }
1954 }
1955
1956 // Check for loading klass from an array
1957 const TypeAryPtr *tary = tp->isa_aryptr();
1958 if( tary != NULL ) {
1959 ciKlass *tary_klass = tary->klass();
1960 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1961 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1962 if (tary->klass_is_exact()) {
1963 return TypeKlassPtr::make(tary_klass);
1964 }
1965 ciArrayKlass *ak = tary->klass()->as_array_klass();
1966 // If the klass is an object array, we defer the question to the
1967 // array component klass.
1968 if( ak->is_obj_array_klass() ) {
1969 assert( ak->is_loaded(), "" );
1970 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1971 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1972 ciInstanceKlass* ik = base_k->as_instance_klass();
1973 // See if we can become precise: no subklasses and no interface
1974 if (!ik->is_interface() && !ik->has_subklass()) {
1975 //assert(!UseExactTypes, "this code should be useless with exact types");
1976 // Add a dependence; if any subclass added we need to recompile
1977 if (!ik->is_final()) {
1978 phase->C->dependencies()->assert_leaf_type(ik);
1979 }
1980 // Return precise array klass
1981 return TypeKlassPtr::make(ak);
1982 }
1983 }
1984 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1985 } else { // Found a type-array?
1986 //assert(!UseExactTypes, "this code should be useless with exact types");
1987 assert( ak->is_type_array_klass(), "" );
1988 return TypeKlassPtr::make(ak); // These are always precise
1989 }
1990 }
1991 }
1992
1993 // Check for loading klass from an array klass
1994 const TypeKlassPtr *tkls = tp->isa_klassptr();
1995 if (tkls != NULL && !StressReflectiveCode) {
1996 ciKlass* klass = tkls->klass();
1997 if( !klass->is_loaded() )
1998 return _type; // Bail out if not loaded
1999 if( klass->is_obj_array_klass() &&
2000 tkls->offset() == in_bytes(objArrayKlass::element_klass_offset())) {
2001 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2002 // // Always returning precise element type is incorrect,
2003 // // e.g., element type could be object and array may contain strings
2004 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2005
2006 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2007 // according to the element type's subclassing.
2008 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2009 }
2010 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2011 tkls->offset() == in_bytes(Klass::super_offset())) {
2012 ciKlass* sup = klass->as_instance_klass()->super();
2013 // The field is Klass::_super. Return its (constant) value.
2014 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2015 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2016 }
2017 }
2018
2019 // Bailout case
2020 return LoadNode::Value(phase);
2021 }
2022
2023 //------------------------------Identity---------------------------------------
2024 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2025 // Also feed through the klass in Allocate(...klass...)._klass.
2026 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2027 return klass_identity_common(phase);
2028 }
2029
2030 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2031 Node* x = LoadNode::Identity(phase);
2032 if (x != this) return x;
2033
2034 // Take apart the address into an oop and and offset.
2035 // Return 'this' if we cannot.
2036 Node* adr = in(MemNode::Address);
2037 intptr_t offset = 0;
2038 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2039 if (base == NULL) return this;
2040 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2041 if (toop == NULL) return this;
2042
2043 // We can fetch the klass directly through an AllocateNode.
2044 // This works even if the klass is not constant (clone or newArray).
2045 if (offset == oopDesc::klass_offset_in_bytes()) {
2046 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2047 if (allocated_klass != NULL) {
2048 return allocated_klass;
2049 }
2050 }
2051
2052 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
2053 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
2054 // See inline_native_Class_query for occurrences of these patterns.
2055 // Java Example: x.getClass().isAssignableFrom(y)
2056 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2057 //
2058 // This improves reflective code, often making the Class
2059 // mirror go completely dead. (Current exception: Class
2060 // mirrors may appear in debug info, but we could clean them out by
2061 // introducing a new debug info operator for klassOop.java_mirror).
2062 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2063 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2064 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2065 // We are loading a special hidden field from a Class mirror,
2066 // the field which points to its Klass or arrayKlass metaobject.
2067 if (base->is_Load()) {
2068 Node* adr2 = base->in(MemNode::Address);
2069 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2070 if (tkls != NULL && !tkls->empty()
2071 && (tkls->klass()->is_instance_klass() ||
2072 tkls->klass()->is_array_klass())
2073 && adr2->is_AddP()
2074 ) {
2075 int mirror_field = in_bytes(Klass::java_mirror_offset());
2076 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2077 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
2078 }
2079 if (tkls->offset() == mirror_field) {
2080 return adr2->in(AddPNode::Base);
2081 }
2082 }
2083 }
2084 }
2085
2086 return this;
2087 }
2088
2089
2090 //------------------------------Value------------------------------------------
2091 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2092 const Type *t = klass_value_common(phase);
2093 if (t == Type::TOP)
2094 return t;
2095
2096 return t->make_narrowoop();
2097 }
2098
2099 //------------------------------Identity---------------------------------------
2100 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2101 // Also feed through the klass in Allocate(...klass...)._klass.
2102 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2103 Node *x = klass_identity_common(phase);
2104
2105 const Type *t = phase->type( x );
2106 if( t == Type::TOP ) return x;
2107 if( t->isa_narrowoop()) return x;
2108
2109 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
2110 }
2111
2112 //------------------------------Value-----------------------------------------
2113 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2114 // Either input is TOP ==> the result is TOP
2115 const Type *t1 = phase->type( in(MemNode::Memory) );
2116 if( t1 == Type::TOP ) return Type::TOP;
2117 Node *adr = in(MemNode::Address);
2118 const Type *t2 = phase->type( adr );
2119 if( t2 == Type::TOP ) return Type::TOP;
2120 const TypePtr *tp = t2->is_ptr();
2121 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2122 const TypeAryPtr *tap = tp->isa_aryptr();
2123 if( !tap ) return _type;
2124 return tap->size();
2125 }
2126
2127 //-------------------------------Ideal---------------------------------------
2128 // Feed through the length in AllocateArray(...length...)._length.
2129 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2130 Node* p = MemNode::Ideal_common(phase, can_reshape);
2131 if (p) return (p == NodeSentinel) ? NULL : p;
2132
2133 // Take apart the address into an oop and and offset.
2134 // Return 'this' if we cannot.
2135 Node* adr = in(MemNode::Address);
2136 intptr_t offset = 0;
2137 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2138 if (base == NULL) return NULL;
2139 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2140 if (tary == NULL) return NULL;
2141
2142 // We can fetch the length directly through an AllocateArrayNode.
2143 // This works even if the length is not constant (clone or newArray).
2144 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2145 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2146 if (alloc != NULL) {
2147 Node* allocated_length = alloc->Ideal_length();
2148 Node* len = alloc->make_ideal_length(tary, phase);
2149 if (allocated_length != len) {
2150 // New CastII improves on this.
2151 return len;
2152 }
2153 }
2154 }
2155
2156 return NULL;
2157 }
2158
2159 //------------------------------Identity---------------------------------------
2160 // Feed through the length in AllocateArray(...length...)._length.
2161 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2162 Node* x = LoadINode::Identity(phase);
2163 if (x != this) return x;
2164
2165 // Take apart the address into an oop and and offset.
2166 // Return 'this' if we cannot.
2167 Node* adr = in(MemNode::Address);
2168 intptr_t offset = 0;
2169 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2170 if (base == NULL) return this;
2171 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2172 if (tary == NULL) return this;
2173
2174 // We can fetch the length directly through an AllocateArrayNode.
2175 // This works even if the length is not constant (clone or newArray).
2176 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2177 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2178 if (alloc != NULL) {
2179 Node* allocated_length = alloc->Ideal_length();
2180 // Do not allow make_ideal_length to allocate a CastII node.
2181 Node* len = alloc->make_ideal_length(tary, phase, false);
2182 if (allocated_length == len) {
2183 // Return allocated_length only if it would not be improved by a CastII.
2184 return allocated_length;
2185 }
2186 }
2187 }
2188
2189 return this;
2190
2191 }
2192
2193 //=============================================================================
2194 //---------------------------StoreNode::make-----------------------------------
2195 // Polymorphic factory method:
2196 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2197 Compile* C = gvn.C;
2198 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2199 ctl != NULL, "raw memory operations should have control edge");
2200
2201 switch (bt) {
2202 case T_BOOLEAN:
2203 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2204 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2205 case T_CHAR:
2206 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2207 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2208 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2209 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2210 case T_ADDRESS:
2211 case T_OBJECT:
2212 #ifdef _LP64
2213 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2214 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2215 adr->bottom_type()->isa_rawptr())) {
2216 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2217 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2218 } else
2219 #endif
2220 {
2221 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2222 }
2223 }
2224 ShouldNotReachHere();
2225 return (StoreNode*)NULL;
2226 }
2227
2228 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2229 bool require_atomic = true;
2230 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2231 }
2232
2233
2234 //--------------------------bottom_type----------------------------------------
2235 const Type *StoreNode::bottom_type() const {
2236 return Type::MEMORY;
2237 }
2238
2239 //------------------------------hash-------------------------------------------
2240 uint StoreNode::hash() const {
2241 // unroll addition of interesting fields
2242 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2243
2244 // Since they are not commoned, do not hash them:
2245 return NO_HASH;
2246 }
2247
2248 //------------------------------Ideal------------------------------------------
2249 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2250 // When a store immediately follows a relevant allocation/initialization,
2251 // try to capture it into the initialization, or hoist it above.
2252 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2253 Node* p = MemNode::Ideal_common(phase, can_reshape);
2254 if (p) return (p == NodeSentinel) ? NULL : p;
2255
2256 Node* mem = in(MemNode::Memory);
2257 Node* address = in(MemNode::Address);
2258
2259 // Back-to-back stores to same address? Fold em up. Generally
2260 // unsafe if I have intervening uses... Also disallowed for StoreCM
2261 // since they must follow each StoreP operation. Redundant StoreCMs
2262 // are eliminated just before matching in final_graph_reshape.
2263 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2264 mem->Opcode() != Op_StoreCM) {
2265 // Looking at a dead closed cycle of memory?
2266 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2267
2268 assert(Opcode() == mem->Opcode() ||
2269 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2270 "no mismatched stores, except on raw memory");
2271
2272 if (mem->outcnt() == 1 && // check for intervening uses
2273 mem->as_Store()->memory_size() <= this->memory_size()) {
2274 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2275 // For example, 'mem' might be the final state at a conditional return.
2276 // Or, 'mem' might be used by some node which is live at the same time
2277 // 'this' is live, which might be unschedulable. So, require exactly
2278 // ONE user, the 'this' store, until such time as we clone 'mem' for
2279 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2280 if (can_reshape) { // (%%% is this an anachronism?)
2281 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2282 phase->is_IterGVN());
2283 } else {
2284 // It's OK to do this in the parser, since DU info is always accurate,
2285 // and the parser always refers to nodes via SafePointNode maps.
2286 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2287 }
2288 return this;
2289 }
2290 }
2291
2292 // Capture an unaliased, unconditional, simple store into an initializer.
2293 // Or, if it is independent of the allocation, hoist it above the allocation.
2294 if (ReduceFieldZeroing && /*can_reshape &&*/
2295 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2296 InitializeNode* init = mem->in(0)->as_Initialize();
2297 intptr_t offset = init->can_capture_store(this, phase);
2298 if (offset > 0) {
2299 Node* moved = init->capture_store(this, offset, phase);
2300 // If the InitializeNode captured me, it made a raw copy of me,
2301 // and I need to disappear.
2302 if (moved != NULL) {
2303 // %%% hack to ensure that Ideal returns a new node:
2304 mem = MergeMemNode::make(phase->C, mem);
2305 return mem; // fold me away
2306 }
2307 }
2308 }
2309
2310 return NULL; // No further progress
2311 }
2312
2313 //------------------------------Value-----------------------------------------
2314 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2315 // Either input is TOP ==> the result is TOP
2316 const Type *t1 = phase->type( in(MemNode::Memory) );
2317 if( t1 == Type::TOP ) return Type::TOP;
2318 const Type *t2 = phase->type( in(MemNode::Address) );
2319 if( t2 == Type::TOP ) return Type::TOP;
2320 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2321 if( t3 == Type::TOP ) return Type::TOP;
2322 return Type::MEMORY;
2323 }
2324
2325 //------------------------------Identity---------------------------------------
2326 // Remove redundant stores:
2327 // Store(m, p, Load(m, p)) changes to m.
2328 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2329 Node *StoreNode::Identity( PhaseTransform *phase ) {
2330 Node* mem = in(MemNode::Memory);
2331 Node* adr = in(MemNode::Address);
2332 Node* val = in(MemNode::ValueIn);
2333
2334 // Load then Store? Then the Store is useless
2335 if (val->is_Load() &&
2336 val->in(MemNode::Address)->eqv_uncast(adr) &&
2337 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2338 val->as_Load()->store_Opcode() == Opcode()) {
2339 return mem;
2340 }
2341
2342 // Two stores in a row of the same value?
2343 if (mem->is_Store() &&
2344 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2345 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2346 mem->Opcode() == Opcode()) {
2347 return mem;
2348 }
2349
2350 // Store of zero anywhere into a freshly-allocated object?
2351 // Then the store is useless.
2352 // (It must already have been captured by the InitializeNode.)
2353 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2354 // a newly allocated object is already all-zeroes everywhere
2355 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2356 return mem;
2357 }
2358
2359 // the store may also apply to zero-bits in an earlier object
2360 Node* prev_mem = find_previous_store(phase);
2361 // Steps (a), (b): Walk past independent stores to find an exact match.
2362 if (prev_mem != NULL) {
2363 Node* prev_val = can_see_stored_value(prev_mem, phase);
2364 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2365 // prev_val and val might differ by a cast; it would be good
2366 // to keep the more informative of the two.
2367 return mem;
2368 }
2369 }
2370 }
2371
2372 return this;
2373 }
2374
2375 //------------------------------match_edge-------------------------------------
2376 // Do we Match on this edge index or not? Match only memory & value
2377 uint StoreNode::match_edge(uint idx) const {
2378 return idx == MemNode::Address || idx == MemNode::ValueIn;
2379 }
2380
2381 //------------------------------cmp--------------------------------------------
2382 // Do not common stores up together. They generally have to be split
2383 // back up anyways, so do not bother.
2384 uint StoreNode::cmp( const Node &n ) const {
2385 return (&n == this); // Always fail except on self
2386 }
2387
2388 //------------------------------Ideal_masked_input-----------------------------
2389 // Check for a useless mask before a partial-word store
2390 // (StoreB ... (AndI valIn conIa) )
2391 // If (conIa & mask == mask) this simplifies to
2392 // (StoreB ... (valIn) )
2393 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2394 Node *val = in(MemNode::ValueIn);
2395 if( val->Opcode() == Op_AndI ) {
2396 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2397 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2398 set_req(MemNode::ValueIn, val->in(1));
2399 return this;
2400 }
2401 }
2402 return NULL;
2403 }
2404
2405
2406 //------------------------------Ideal_sign_extended_input----------------------
2407 // Check for useless sign-extension before a partial-word store
2408 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2409 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2410 // (StoreB ... (valIn) )
2411 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2412 Node *val = in(MemNode::ValueIn);
2413 if( val->Opcode() == Op_RShiftI ) {
2414 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2415 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2416 Node *shl = val->in(1);
2417 if( shl->Opcode() == Op_LShiftI ) {
2418 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2419 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2420 set_req(MemNode::ValueIn, shl->in(1));
2421 return this;
2422 }
2423 }
2424 }
2425 }
2426 return NULL;
2427 }
2428
2429 //------------------------------value_never_loaded-----------------------------------
2430 // Determine whether there are any possible loads of the value stored.
2431 // For simplicity, we actually check if there are any loads from the
2432 // address stored to, not just for loads of the value stored by this node.
2433 //
2434 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2435 Node *adr = in(Address);
2436 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2437 if (adr_oop == NULL)
2438 return false;
2439 if (!adr_oop->is_known_instance_field())
2440 return false; // if not a distinct instance, there may be aliases of the address
2441 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2442 Node *use = adr->fast_out(i);
2443 int opc = use->Opcode();
2444 if (use->is_Load() || use->is_LoadStore()) {
2445 return false;
2446 }
2447 }
2448 return true;
2449 }
2450
2451 //=============================================================================
2452 //------------------------------Ideal------------------------------------------
2453 // If the store is from an AND mask that leaves the low bits untouched, then
2454 // we can skip the AND operation. If the store is from a sign-extension
2455 // (a left shift, then right shift) we can skip both.
2456 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2457 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2458 if( progress != NULL ) return progress;
2459
2460 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2461 if( progress != NULL ) return progress;
2462
2463 // Finally check the default case
2464 return StoreNode::Ideal(phase, can_reshape);
2465 }
2466
2467 //=============================================================================
2468 //------------------------------Ideal------------------------------------------
2469 // If the store is from an AND mask that leaves the low bits untouched, then
2470 // we can skip the AND operation
2471 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2472 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2473 if( progress != NULL ) return progress;
2474
2475 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2476 if( progress != NULL ) return progress;
2477
2478 // Finally check the default case
2479 return StoreNode::Ideal(phase, can_reshape);
2480 }
2481
2482 //=============================================================================
2483 //------------------------------Identity---------------------------------------
2484 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2485 // No need to card mark when storing a null ptr
2486 Node* my_store = in(MemNode::OopStore);
2487 if (my_store->is_Store()) {
2488 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2489 if( t1 == TypePtr::NULL_PTR ) {
2490 return in(MemNode::Memory);
2491 }
2492 }
2493 return this;
2494 }
2495
2496 //=============================================================================
2497 //------------------------------Ideal---------------------------------------
2498 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2499 Node* progress = StoreNode::Ideal(phase, can_reshape);
2500 if (progress != NULL) return progress;
2501
2502 Node* my_store = in(MemNode::OopStore);
2503 if (my_store->is_MergeMem()) {
2504 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2505 set_req(MemNode::OopStore, mem);
2506 return this;
2507 }
2508
2509 return NULL;
2510 }
2511
2512 //------------------------------Value-----------------------------------------
2513 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2514 // Either input is TOP ==> the result is TOP
2515 const Type *t = phase->type( in(MemNode::Memory) );
2516 if( t == Type::TOP ) return Type::TOP;
2517 t = phase->type( in(MemNode::Address) );
2518 if( t == Type::TOP ) return Type::TOP;
2519 t = phase->type( in(MemNode::ValueIn) );
2520 if( t == Type::TOP ) return Type::TOP;
2521 // If extra input is TOP ==> the result is TOP
2522 t = phase->type( in(MemNode::OopStore) );
2523 if( t == Type::TOP ) return Type::TOP;
2524
2525 return StoreNode::Value( phase );
2526 }
2527
2528
2529 //=============================================================================
2530 //----------------------------------SCMemProjNode------------------------------
2531 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2532 {
2533 return bottom_type();
2534 }
2535
2536 //=============================================================================
2537 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2538 init_req(MemNode::Control, c );
2539 init_req(MemNode::Memory , mem);
2540 init_req(MemNode::Address, adr);
2541 init_req(MemNode::ValueIn, val);
2542 init_req( ExpectedIn, ex );
2543 init_class_id(Class_LoadStore);
2544
2545 }
2546
2547 //=============================================================================
2548 //-------------------------------adr_type--------------------------------------
2549 // Do we Match on this edge index or not? Do not match memory
2550 const TypePtr* ClearArrayNode::adr_type() const {
2551 Node *adr = in(3);
2552 return MemNode::calculate_adr_type(adr->bottom_type());
2553 }
2554
2555 //------------------------------match_edge-------------------------------------
2556 // Do we Match on this edge index or not? Do not match memory
2557 uint ClearArrayNode::match_edge(uint idx) const {
2558 return idx > 1;
2559 }
2560
2561 //------------------------------Identity---------------------------------------
2562 // Clearing a zero length array does nothing
2563 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2564 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2565 }
2566
2567 //------------------------------Idealize---------------------------------------
2568 // Clearing a short array is faster with stores
2569 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2570 const int unit = BytesPerLong;
2571 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2572 if (!t) return NULL;
2573 if (!t->is_con()) return NULL;
2574 intptr_t raw_count = t->get_con();
2575 intptr_t size = raw_count;
2576 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2577 // Clearing nothing uses the Identity call.
2578 // Negative clears are possible on dead ClearArrays
2579 // (see jck test stmt114.stmt11402.val).
2580 if (size <= 0 || size % unit != 0) return NULL;
2581 intptr_t count = size / unit;
2582 // Length too long; use fast hardware clear
2583 if (size > Matcher::init_array_short_size) return NULL;
2584 Node *mem = in(1);
2585 if( phase->type(mem)==Type::TOP ) return NULL;
2586 Node *adr = in(3);
2587 const Type* at = phase->type(adr);
2588 if( at==Type::TOP ) return NULL;
2589 const TypePtr* atp = at->isa_ptr();
2590 // adjust atp to be the correct array element address type
2591 if (atp == NULL) atp = TypePtr::BOTTOM;
2592 else atp = atp->add_offset(Type::OffsetBot);
2593 // Get base for derived pointer purposes
2594 if( adr->Opcode() != Op_AddP ) Unimplemented();
2595 Node *base = adr->in(1);
2596
2597 Node *zero = phase->makecon(TypeLong::ZERO);
2598 Node *off = phase->MakeConX(BytesPerLong);
2599 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2600 count--;
2601 while( count-- ) {
2602 mem = phase->transform(mem);
2603 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2604 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2605 }
2606 return mem;
2607 }
2608
2609 //----------------------------step_through----------------------------------
2610 // Return allocation input memory edge if it is different instance
2611 // or itself if it is the one we are looking for.
2612 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2613 Node* n = *np;
2614 assert(n->is_ClearArray(), "sanity");
2615 intptr_t offset;
2616 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2617 // This method is called only before Allocate nodes are expanded during
2618 // macro nodes expansion. Before that ClearArray nodes are only generated
2619 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2620 assert(alloc != NULL, "should have allocation");
2621 if (alloc->_idx == instance_id) {
2622 // Can not bypass initialization of the instance we are looking for.
2623 return false;
2624 }
2625 // Otherwise skip it.
2626 InitializeNode* init = alloc->initialization();
2627 if (init != NULL)
2628 *np = init->in(TypeFunc::Memory);
2629 else
2630 *np = alloc->in(TypeFunc::Memory);
2631 return true;
2632 }
2633
2634 //----------------------------clear_memory-------------------------------------
2635 // Generate code to initialize object storage to zero.
2636 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2637 intptr_t start_offset,
2638 Node* end_offset,
2639 PhaseGVN* phase) {
2640 Compile* C = phase->C;
2641 intptr_t offset = start_offset;
2642
2643 int unit = BytesPerLong;
2644 if ((offset % unit) != 0) {
2645 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2646 adr = phase->transform(adr);
2647 const TypePtr* atp = TypeRawPtr::BOTTOM;
2648 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2649 mem = phase->transform(mem);
2650 offset += BytesPerInt;
2651 }
2652 assert((offset % unit) == 0, "");
2653
2654 // Initialize the remaining stuff, if any, with a ClearArray.
2655 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2656 }
2657
2658 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2659 Node* start_offset,
2660 Node* end_offset,
2661 PhaseGVN* phase) {
2662 if (start_offset == end_offset) {
2663 // nothing to do
2664 return mem;
2665 }
2666
2667 Compile* C = phase->C;
2668 int unit = BytesPerLong;
2669 Node* zbase = start_offset;
2670 Node* zend = end_offset;
2671
2672 // Scale to the unit required by the CPU:
2673 if (!Matcher::init_array_count_is_in_bytes) {
2674 Node* shift = phase->intcon(exact_log2(unit));
2675 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2676 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2677 }
2678
2679 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2680 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2681
2682 // Bulk clear double-words
2683 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2684 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2685 return phase->transform(mem);
2686 }
2687
2688 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2689 intptr_t start_offset,
2690 intptr_t end_offset,
2691 PhaseGVN* phase) {
2692 if (start_offset == end_offset) {
2693 // nothing to do
2694 return mem;
2695 }
2696
2697 Compile* C = phase->C;
2698 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2699 intptr_t done_offset = end_offset;
2700 if ((done_offset % BytesPerLong) != 0) {
2701 done_offset -= BytesPerInt;
2702 }
2703 if (done_offset > start_offset) {
2704 mem = clear_memory(ctl, mem, dest,
2705 start_offset, phase->MakeConX(done_offset), phase);
2706 }
2707 if (done_offset < end_offset) { // emit the final 32-bit store
2708 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2709 adr = phase->transform(adr);
2710 const TypePtr* atp = TypeRawPtr::BOTTOM;
2711 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2712 mem = phase->transform(mem);
2713 done_offset += BytesPerInt;
2714 }
2715 assert(done_offset == end_offset, "");
2716 return mem;
2717 }
2718
2719 //=============================================================================
2720 // Do not match memory edge.
2721 uint StrIntrinsicNode::match_edge(uint idx) const {
2722 return idx == 2 || idx == 3;
2723 }
2724
2725 //------------------------------Ideal------------------------------------------
2726 // Return a node which is more "ideal" than the current node. Strip out
2727 // control copies
2728 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2729 if (remove_dead_region(phase, can_reshape)) return this;
2730 // Don't bother trying to transform a dead node
2731 if (in(0) && in(0)->is_top()) return NULL;
2732
2733 if (can_reshape) {
2734 Node* mem = phase->transform(in(MemNode::Memory));
2735 // If transformed to a MergeMem, get the desired slice
2736 uint alias_idx = phase->C->get_alias_index(adr_type());
2737 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2738 if (mem != in(MemNode::Memory)) {
2739 set_req(MemNode::Memory, mem);
2740 return this;
2741 }
2742 }
2743 return NULL;
2744 }
2745
2746 //------------------------------Value------------------------------------------
2747 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2748 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2749 return bottom_type();
2750 }
2751
2752 //=============================================================================
2753 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2754 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2755 _adr_type(C->get_adr_type(alias_idx))
2756 {
2757 init_class_id(Class_MemBar);
2758 Node* top = C->top();
2759 init_req(TypeFunc::I_O,top);
2760 init_req(TypeFunc::FramePtr,top);
2761 init_req(TypeFunc::ReturnAdr,top);
2762 if (precedent != NULL)
2763 init_req(TypeFunc::Parms, precedent);
2764 }
2765
2766 //------------------------------cmp--------------------------------------------
2767 uint MemBarNode::hash() const { return NO_HASH; }
2768 uint MemBarNode::cmp( const Node &n ) const {
2769 return (&n == this); // Always fail except on self
2770 }
2771
2772 //------------------------------make-------------------------------------------
2773 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2774 int len = Precedent + (pn == NULL? 0: 1);
2775 switch (opcode) {
2776 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2777 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2778 case Op_MemBarAcquireLock: return new(C, len) MemBarAcquireLockNode(C, atp, pn);
2779 case Op_MemBarReleaseLock: return new(C, len) MemBarReleaseLockNode(C, atp, pn);
2780 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2781 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2782 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2783 case Op_MemBarStoreStore: return new(C, len) MemBarStoreStoreNode(C, atp, pn);
2784 default: ShouldNotReachHere(); return NULL;
2785 }
2786 }
2787
2788 //------------------------------Ideal------------------------------------------
2789 // Return a node which is more "ideal" than the current node. Strip out
2790 // control copies
2791 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2792 if (remove_dead_region(phase, can_reshape)) return this;
2793 // Don't bother trying to transform a dead node
2794 if (in(0) && in(0)->is_top()) return NULL;
2795
2796 // Eliminate volatile MemBars for scalar replaced objects.
2797 if (can_reshape && req() == (Precedent+1) &&
2798 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2799 // Volatile field loads and stores.
2800 Node* my_mem = in(MemBarNode::Precedent);
2801 if (my_mem != NULL && my_mem->is_Mem()) {
2802 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2803 // Check for scalar replaced object reference.
2804 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2805 t_oop->offset() != Type::OffsetBot &&
2806 t_oop->offset() != Type::OffsetTop) {
2807 // Replace MemBar projections by its inputs.
2808 PhaseIterGVN* igvn = phase->is_IterGVN();
2809 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2810 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2811 // Must return either the original node (now dead) or a new node
2812 // (Do not return a top here, since that would break the uniqueness of top.)
2813 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2814 }
2815 }
2816 }
2817 return NULL;
2818 }
2819
2820 //------------------------------Value------------------------------------------
2821 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2822 if( !in(0) ) return Type::TOP;
2823 if( phase->type(in(0)) == Type::TOP )
2824 return Type::TOP;
2825 return TypeTuple::MEMBAR;
2826 }
2827
2828 //------------------------------match------------------------------------------
2829 // Construct projections for memory.
2830 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2831 switch (proj->_con) {
2832 case TypeFunc::Control:
2833 case TypeFunc::Memory:
2834 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2835 }
2836 ShouldNotReachHere();
2837 return NULL;
2838 }
2839
2840 //===========================InitializeNode====================================
2841 // SUMMARY:
2842 // This node acts as a memory barrier on raw memory, after some raw stores.
2843 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2844 // The Initialize can 'capture' suitably constrained stores as raw inits.
2845 // It can coalesce related raw stores into larger units (called 'tiles').
2846 // It can avoid zeroing new storage for memory units which have raw inits.
2847 // At macro-expansion, it is marked 'complete', and does not optimize further.
2848 //
2849 // EXAMPLE:
2850 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2851 // ctl = incoming control; mem* = incoming memory
2852 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2853 // First allocate uninitialized memory and fill in the header:
2854 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2855 // ctl := alloc.Control; mem* := alloc.Memory*
2856 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2857 // Then initialize to zero the non-header parts of the raw memory block:
2858 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2859 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2860 // After the initialize node executes, the object is ready for service:
2861 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2862 // Suppose its body is immediately initialized as {1,2}:
2863 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2864 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2865 // mem.SLICE(#short[*]) := store2
2866 //
2867 // DETAILS:
2868 // An InitializeNode collects and isolates object initialization after
2869 // an AllocateNode and before the next possible safepoint. As a
2870 // memory barrier (MemBarNode), it keeps critical stores from drifting
2871 // down past any safepoint or any publication of the allocation.
2872 // Before this barrier, a newly-allocated object may have uninitialized bits.
2873 // After this barrier, it may be treated as a real oop, and GC is allowed.
2874 //
2875 // The semantics of the InitializeNode include an implicit zeroing of
2876 // the new object from object header to the end of the object.
2877 // (The object header and end are determined by the AllocateNode.)
2878 //
2879 // Certain stores may be added as direct inputs to the InitializeNode.
2880 // These stores must update raw memory, and they must be to addresses
2881 // derived from the raw address produced by AllocateNode, and with
2882 // a constant offset. They must be ordered by increasing offset.
2883 // The first one is at in(RawStores), the last at in(req()-1).
2884 // Unlike most memory operations, they are not linked in a chain,
2885 // but are displayed in parallel as users of the rawmem output of
2886 // the allocation.
2887 //
2888 // (See comments in InitializeNode::capture_store, which continue
2889 // the example given above.)
2890 //
2891 // When the associated Allocate is macro-expanded, the InitializeNode
2892 // may be rewritten to optimize collected stores. A ClearArrayNode
2893 // may also be created at that point to represent any required zeroing.
2894 // The InitializeNode is then marked 'complete', prohibiting further
2895 // capturing of nearby memory operations.
2896 //
2897 // During macro-expansion, all captured initializations which store
2898 // constant values of 32 bits or smaller are coalesced (if advantageous)
2899 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2900 // initialized in fewer memory operations. Memory words which are
2901 // covered by neither tiles nor non-constant stores are pre-zeroed
2902 // by explicit stores of zero. (The code shape happens to do all
2903 // zeroing first, then all other stores, with both sequences occurring
2904 // in order of ascending offsets.)
2905 //
2906 // Alternatively, code may be inserted between an AllocateNode and its
2907 // InitializeNode, to perform arbitrary initialization of the new object.
2908 // E.g., the object copying intrinsics insert complex data transfers here.
2909 // The initialization must then be marked as 'complete' disable the
2910 // built-in zeroing semantics and the collection of initializing stores.
2911 //
2912 // While an InitializeNode is incomplete, reads from the memory state
2913 // produced by it are optimizable if they match the control edge and
2914 // new oop address associated with the allocation/initialization.
2915 // They return a stored value (if the offset matches) or else zero.
2916 // A write to the memory state, if it matches control and address,
2917 // and if it is to a constant offset, may be 'captured' by the
2918 // InitializeNode. It is cloned as a raw memory operation and rewired
2919 // inside the initialization, to the raw oop produced by the allocation.
2920 // Operations on addresses which are provably distinct (e.g., to
2921 // other AllocateNodes) are allowed to bypass the initialization.
2922 //
2923 // The effect of all this is to consolidate object initialization
2924 // (both arrays and non-arrays, both piecewise and bulk) into a
2925 // single location, where it can be optimized as a unit.
2926 //
2927 // Only stores with an offset less than TrackedInitializationLimit words
2928 // will be considered for capture by an InitializeNode. This puts a
2929 // reasonable limit on the complexity of optimized initializations.
2930
2931 //---------------------------InitializeNode------------------------------------
2932 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2933 : _is_complete(Incomplete), _does_not_escape(false),
2934 MemBarNode(C, adr_type, rawoop)
2935 {
2936 init_class_id(Class_Initialize);
2937
2938 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2939 assert(in(RawAddress) == rawoop, "proper init");
2940 // Note: allocation() can be NULL, for secondary initialization barriers
2941 }
2942
2943 // Since this node is not matched, it will be processed by the
2944 // register allocator. Declare that there are no constraints
2945 // on the allocation of the RawAddress edge.
2946 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2947 // This edge should be set to top, by the set_complete. But be conservative.
2948 if (idx == InitializeNode::RawAddress)
2949 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2950 return RegMask::Empty;
2951 }
2952
2953 Node* InitializeNode::memory(uint alias_idx) {
2954 Node* mem = in(Memory);
2955 if (mem->is_MergeMem()) {
2956 return mem->as_MergeMem()->memory_at(alias_idx);
2957 } else {
2958 // incoming raw memory is not split
2959 return mem;
2960 }
2961 }
2962
2963 bool InitializeNode::is_non_zero() {
2964 if (is_complete()) return false;
2965 remove_extra_zeroes();
2966 return (req() > RawStores);
2967 }
2968
2969 void InitializeNode::set_complete(PhaseGVN* phase) {
2970 assert(!is_complete(), "caller responsibility");
2971 _is_complete = Complete;
2972
2973 // After this node is complete, it contains a bunch of
2974 // raw-memory initializations. There is no need for
2975 // it to have anything to do with non-raw memory effects.
2976 // Therefore, tell all non-raw users to re-optimize themselves,
2977 // after skipping the memory effects of this initialization.
2978 PhaseIterGVN* igvn = phase->is_IterGVN();
2979 if (igvn) igvn->add_users_to_worklist(this);
2980 }
2981
2982 // convenience function
2983 // return false if the init contains any stores already
2984 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2985 InitializeNode* init = initialization();
2986 if (init == NULL || init->is_complete()) return false;
2987 init->remove_extra_zeroes();
2988 // for now, if this allocation has already collected any inits, bail:
2989 if (init->is_non_zero()) return false;
2990 init->set_complete(phase);
2991 return true;
2992 }
2993
2994 void InitializeNode::remove_extra_zeroes() {
2995 if (req() == RawStores) return;
2996 Node* zmem = zero_memory();
2997 uint fill = RawStores;
2998 for (uint i = fill; i < req(); i++) {
2999 Node* n = in(i);
3000 if (n->is_top() || n == zmem) continue; // skip
3001 if (fill < i) set_req(fill, n); // compact
3002 ++fill;
3003 }
3004 // delete any empty spaces created:
3005 while (fill < req()) {
3006 del_req(fill);
3007 }
3008 }
3009
3010 // Helper for remembering which stores go with which offsets.
3011 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3012 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3013 intptr_t offset = -1;
3014 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3015 phase, offset);
3016 if (base == NULL) return -1; // something is dead,
3017 if (offset < 0) return -1; // dead, dead
3018 return offset;
3019 }
3020
3021 // Helper for proving that an initialization expression is
3022 // "simple enough" to be folded into an object initialization.
3023 // Attempts to prove that a store's initial value 'n' can be captured
3024 // within the initialization without creating a vicious cycle, such as:
3025 // { Foo p = new Foo(); p.next = p; }
3026 // True for constants and parameters and small combinations thereof.
3027 bool InitializeNode::detect_init_independence(Node* n,
3028 bool st_is_pinned,
3029 int& count) {
3030 if (n == NULL) return true; // (can this really happen?)
3031 if (n->is_Proj()) n = n->in(0);
3032 if (n == this) return false; // found a cycle
3033 if (n->is_Con()) return true;
3034 if (n->is_Start()) return true; // params, etc., are OK
3035 if (n->is_Root()) return true; // even better
3036
3037 Node* ctl = n->in(0);
3038 if (ctl != NULL && !ctl->is_top()) {
3039 if (ctl->is_Proj()) ctl = ctl->in(0);
3040 if (ctl == this) return false;
3041
3042 // If we already know that the enclosing memory op is pinned right after
3043 // the init, then any control flow that the store has picked up
3044 // must have preceded the init, or else be equal to the init.
3045 // Even after loop optimizations (which might change control edges)
3046 // a store is never pinned *before* the availability of its inputs.
3047 if (!MemNode::all_controls_dominate(n, this))
3048 return false; // failed to prove a good control
3049
3050 }
3051
3052 // Check data edges for possible dependencies on 'this'.
3053 if ((count += 1) > 20) return false; // complexity limit
3054 for (uint i = 1; i < n->req(); i++) {
3055 Node* m = n->in(i);
3056 if (m == NULL || m == n || m->is_top()) continue;
3057 uint first_i = n->find_edge(m);
3058 if (i != first_i) continue; // process duplicate edge just once
3059 if (!detect_init_independence(m, st_is_pinned, count)) {
3060 return false;
3061 }
3062 }
3063
3064 return true;
3065 }
3066
3067 // Here are all the checks a Store must pass before it can be moved into
3068 // an initialization. Returns zero if a check fails.
3069 // On success, returns the (constant) offset to which the store applies,
3070 // within the initialized memory.
3071 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
3072 const int FAIL = 0;
3073 if (st->req() != MemNode::ValueIn + 1)
3074 return FAIL; // an inscrutable StoreNode (card mark?)
3075 Node* ctl = st->in(MemNode::Control);
3076 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3077 return FAIL; // must be unconditional after the initialization
3078 Node* mem = st->in(MemNode::Memory);
3079 if (!(mem->is_Proj() && mem->in(0) == this))
3080 return FAIL; // must not be preceded by other stores
3081 Node* adr = st->in(MemNode::Address);
3082 intptr_t offset;
3083 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3084 if (alloc == NULL)
3085 return FAIL; // inscrutable address
3086 if (alloc != allocation())
3087 return FAIL; // wrong allocation! (store needs to float up)
3088 Node* val = st->in(MemNode::ValueIn);
3089 int complexity_count = 0;
3090 if (!detect_init_independence(val, true, complexity_count))
3091 return FAIL; // stored value must be 'simple enough'
3092
3093 return offset; // success
3094 }
3095
3096 // Find the captured store in(i) which corresponds to the range
3097 // [start..start+size) in the initialized object.
3098 // If there is one, return its index i. If there isn't, return the
3099 // negative of the index where it should be inserted.
3100 // Return 0 if the queried range overlaps an initialization boundary
3101 // or if dead code is encountered.
3102 // If size_in_bytes is zero, do not bother with overlap checks.
3103 int InitializeNode::captured_store_insertion_point(intptr_t start,
3104 int size_in_bytes,
3105 PhaseTransform* phase) {
3106 const int FAIL = 0, MAX_STORE = BytesPerLong;
3107
3108 if (is_complete())
3109 return FAIL; // arraycopy got here first; punt
3110
3111 assert(allocation() != NULL, "must be present");
3112
3113 // no negatives, no header fields:
3114 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3115
3116 // after a certain size, we bail out on tracking all the stores:
3117 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3118 if (start >= ti_limit) return FAIL;
3119
3120 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3121 if (i >= limit) return -(int)i; // not found; here is where to put it
3122
3123 Node* st = in(i);
3124 intptr_t st_off = get_store_offset(st, phase);
3125 if (st_off < 0) {
3126 if (st != zero_memory()) {
3127 return FAIL; // bail out if there is dead garbage
3128 }
3129 } else if (st_off > start) {
3130 // ...we are done, since stores are ordered
3131 if (st_off < start + size_in_bytes) {
3132 return FAIL; // the next store overlaps
3133 }
3134 return -(int)i; // not found; here is where to put it
3135 } else if (st_off < start) {
3136 if (size_in_bytes != 0 &&
3137 start < st_off + MAX_STORE &&
3138 start < st_off + st->as_Store()->memory_size()) {
3139 return FAIL; // the previous store overlaps
3140 }
3141 } else {
3142 if (size_in_bytes != 0 &&
3143 st->as_Store()->memory_size() != size_in_bytes) {
3144 return FAIL; // mismatched store size
3145 }
3146 return i;
3147 }
3148
3149 ++i;
3150 }
3151 }
3152
3153 // Look for a captured store which initializes at the offset 'start'
3154 // with the given size. If there is no such store, and no other
3155 // initialization interferes, then return zero_memory (the memory
3156 // projection of the AllocateNode).
3157 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3158 PhaseTransform* phase) {
3159 assert(stores_are_sane(phase), "");
3160 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3161 if (i == 0) {
3162 return NULL; // something is dead
3163 } else if (i < 0) {
3164 return zero_memory(); // just primordial zero bits here
3165 } else {
3166 Node* st = in(i); // here is the store at this position
3167 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3168 return st;
3169 }
3170 }
3171
3172 // Create, as a raw pointer, an address within my new object at 'offset'.
3173 Node* InitializeNode::make_raw_address(intptr_t offset,
3174 PhaseTransform* phase) {
3175 Node* addr = in(RawAddress);
3176 if (offset != 0) {
3177 Compile* C = phase->C;
3178 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3179 phase->MakeConX(offset)) );
3180 }
3181 return addr;
3182 }
3183
3184 // Clone the given store, converting it into a raw store
3185 // initializing a field or element of my new object.
3186 // Caller is responsible for retiring the original store,
3187 // with subsume_node or the like.
3188 //
3189 // From the example above InitializeNode::InitializeNode,
3190 // here are the old stores to be captured:
3191 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3192 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3193 //
3194 // Here is the changed code; note the extra edges on init:
3195 // alloc = (Allocate ...)
3196 // rawoop = alloc.RawAddress
3197 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3198 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3199 // init = (Initialize alloc.Control alloc.Memory rawoop
3200 // rawstore1 rawstore2)
3201 //
3202 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3203 PhaseTransform* phase) {
3204 assert(stores_are_sane(phase), "");
3205
3206 if (start < 0) return NULL;
3207 assert(can_capture_store(st, phase) == start, "sanity");
3208
3209 Compile* C = phase->C;
3210 int size_in_bytes = st->memory_size();
3211 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3212 if (i == 0) return NULL; // bail out
3213 Node* prev_mem = NULL; // raw memory for the captured store
3214 if (i > 0) {
3215 prev_mem = in(i); // there is a pre-existing store under this one
3216 set_req(i, C->top()); // temporarily disconnect it
3217 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3218 } else {
3219 i = -i; // no pre-existing store
3220 prev_mem = zero_memory(); // a slice of the newly allocated object
3221 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3222 set_req(--i, C->top()); // reuse this edge; it has been folded away
3223 else
3224 ins_req(i, C->top()); // build a new edge
3225 }
3226 Node* new_st = st->clone();
3227 new_st->set_req(MemNode::Control, in(Control));
3228 new_st->set_req(MemNode::Memory, prev_mem);
3229 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3230 new_st = phase->transform(new_st);
3231
3232 // At this point, new_st might have swallowed a pre-existing store
3233 // at the same offset, or perhaps new_st might have disappeared,
3234 // if it redundantly stored the same value (or zero to fresh memory).
3235
3236 // In any case, wire it in:
3237 set_req(i, new_st);
3238
3239 // The caller may now kill the old guy.
3240 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3241 assert(check_st == new_st || check_st == NULL, "must be findable");
3242 assert(!is_complete(), "");
3243 return new_st;
3244 }
3245
3246 static bool store_constant(jlong* tiles, int num_tiles,
3247 intptr_t st_off, int st_size,
3248 jlong con) {
3249 if ((st_off & (st_size-1)) != 0)
3250 return false; // strange store offset (assume size==2**N)
3251 address addr = (address)tiles + st_off;
3252 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3253 switch (st_size) {
3254 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3255 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3256 case sizeof(jint): *(jint*) addr = (jint) con; break;
3257 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3258 default: return false; // strange store size (detect size!=2**N here)
3259 }
3260 return true; // return success to caller
3261 }
3262
3263 // Coalesce subword constants into int constants and possibly
3264 // into long constants. The goal, if the CPU permits,
3265 // is to initialize the object with a small number of 64-bit tiles.
3266 // Also, convert floating-point constants to bit patterns.
3267 // Non-constants are not relevant to this pass.
3268 //
3269 // In terms of the running example on InitializeNode::InitializeNode
3270 // and InitializeNode::capture_store, here is the transformation
3271 // of rawstore1 and rawstore2 into rawstore12:
3272 // alloc = (Allocate ...)
3273 // rawoop = alloc.RawAddress
3274 // tile12 = 0x00010002
3275 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3276 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3277 //
3278 void
3279 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3280 Node* size_in_bytes,
3281 PhaseGVN* phase) {
3282 Compile* C = phase->C;
3283
3284 assert(stores_are_sane(phase), "");
3285 // Note: After this pass, they are not completely sane,
3286 // since there may be some overlaps.
3287
3288 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3289
3290 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3291 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3292 size_limit = MIN2(size_limit, ti_limit);
3293 size_limit = align_size_up(size_limit, BytesPerLong);
3294 int num_tiles = size_limit / BytesPerLong;
3295
3296 // allocate space for the tile map:
3297 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3298 jlong tiles_buf[small_len];
3299 Node* nodes_buf[small_len];
3300 jlong inits_buf[small_len];
3301 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3302 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3303 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3304 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3305 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3306 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3307 // tiles: exact bitwise model of all primitive constants
3308 // nodes: last constant-storing node subsumed into the tiles model
3309 // inits: which bytes (in each tile) are touched by any initializations
3310
3311 //// Pass A: Fill in the tile model with any relevant stores.
3312
3313 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3314 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3315 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3316 Node* zmem = zero_memory(); // initially zero memory state
3317 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3318 Node* st = in(i);
3319 intptr_t st_off = get_store_offset(st, phase);
3320
3321 // Figure out the store's offset and constant value:
3322 if (st_off < header_size) continue; //skip (ignore header)
3323 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3324 int st_size = st->as_Store()->memory_size();
3325 if (st_off + st_size > size_limit) break;
3326
3327 // Record which bytes are touched, whether by constant or not.
3328 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3329 continue; // skip (strange store size)
3330
3331 const Type* val = phase->type(st->in(MemNode::ValueIn));
3332 if (!val->singleton()) continue; //skip (non-con store)
3333 BasicType type = val->basic_type();
3334
3335 jlong con = 0;
3336 switch (type) {
3337 case T_INT: con = val->is_int()->get_con(); break;
3338 case T_LONG: con = val->is_long()->get_con(); break;
3339 case T_FLOAT: con = jint_cast(val->getf()); break;
3340 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3341 default: continue; //skip (odd store type)
3342 }
3343
3344 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3345 st->Opcode() == Op_StoreL) {
3346 continue; // This StoreL is already optimal.
3347 }
3348
3349 // Store down the constant.
3350 store_constant(tiles, num_tiles, st_off, st_size, con);
3351
3352 intptr_t j = st_off >> LogBytesPerLong;
3353
3354 if (type == T_INT && st_size == BytesPerInt
3355 && (st_off & BytesPerInt) == BytesPerInt) {
3356 jlong lcon = tiles[j];
3357 if (!Matcher::isSimpleConstant64(lcon) &&
3358 st->Opcode() == Op_StoreI) {
3359 // This StoreI is already optimal by itself.
3360 jint* intcon = (jint*) &tiles[j];
3361 intcon[1] = 0; // undo the store_constant()
3362
3363 // If the previous store is also optimal by itself, back up and
3364 // undo the action of the previous loop iteration... if we can.
3365 // But if we can't, just let the previous half take care of itself.
3366 st = nodes[j];
3367 st_off -= BytesPerInt;
3368 con = intcon[0];
3369 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3370 assert(st_off >= header_size, "still ignoring header");
3371 assert(get_store_offset(st, phase) == st_off, "must be");
3372 assert(in(i-1) == zmem, "must be");
3373 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3374 assert(con == tcon->is_int()->get_con(), "must be");
3375 // Undo the effects of the previous loop trip, which swallowed st:
3376 intcon[0] = 0; // undo store_constant()
3377 set_req(i-1, st); // undo set_req(i, zmem)
3378 nodes[j] = NULL; // undo nodes[j] = st
3379 --old_subword; // undo ++old_subword
3380 }
3381 continue; // This StoreI is already optimal.
3382 }
3383 }
3384
3385 // This store is not needed.
3386 set_req(i, zmem);
3387 nodes[j] = st; // record for the moment
3388 if (st_size < BytesPerLong) // something has changed
3389 ++old_subword; // includes int/float, but who's counting...
3390 else ++old_long;
3391 }
3392
3393 if ((old_subword + old_long) == 0)
3394 return; // nothing more to do
3395
3396 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3397 // Be sure to insert them before overlapping non-constant stores.
3398 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3399 for (int j = 0; j < num_tiles; j++) {
3400 jlong con = tiles[j];
3401 jlong init = inits[j];
3402 if (con == 0) continue;
3403 jint con0, con1; // split the constant, address-wise
3404 jint init0, init1; // split the init map, address-wise
3405 { union { jlong con; jint intcon[2]; } u;
3406 u.con = con;
3407 con0 = u.intcon[0];
3408 con1 = u.intcon[1];
3409 u.con = init;
3410 init0 = u.intcon[0];
3411 init1 = u.intcon[1];
3412 }
3413
3414 Node* old = nodes[j];
3415 assert(old != NULL, "need the prior store");
3416 intptr_t offset = (j * BytesPerLong);
3417
3418 bool split = !Matcher::isSimpleConstant64(con);
3419
3420 if (offset < header_size) {
3421 assert(offset + BytesPerInt >= header_size, "second int counts");
3422 assert(*(jint*)&tiles[j] == 0, "junk in header");
3423 split = true; // only the second word counts
3424 // Example: int a[] = { 42 ... }
3425 } else if (con0 == 0 && init0 == -1) {
3426 split = true; // first word is covered by full inits
3427 // Example: int a[] = { ... foo(), 42 ... }
3428 } else if (con1 == 0 && init1 == -1) {
3429 split = true; // second word is covered by full inits
3430 // Example: int a[] = { ... 42, foo() ... }
3431 }
3432
3433 // Here's a case where init0 is neither 0 nor -1:
3434 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3435 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3436 // In this case the tile is not split; it is (jlong)42.
3437 // The big tile is stored down, and then the foo() value is inserted.
3438 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3439
3440 Node* ctl = old->in(MemNode::Control);
3441 Node* adr = make_raw_address(offset, phase);
3442 const TypePtr* atp = TypeRawPtr::BOTTOM;
3443
3444 // One or two coalesced stores to plop down.
3445 Node* st[2];
3446 intptr_t off[2];
3447 int nst = 0;
3448 if (!split) {
3449 ++new_long;
3450 off[nst] = offset;
3451 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3452 phase->longcon(con), T_LONG);
3453 } else {
3454 // Omit either if it is a zero.
3455 if (con0 != 0) {
3456 ++new_int;
3457 off[nst] = offset;
3458 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3459 phase->intcon(con0), T_INT);
3460 }
3461 if (con1 != 0) {
3462 ++new_int;
3463 offset += BytesPerInt;
3464 adr = make_raw_address(offset, phase);
3465 off[nst] = offset;
3466 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3467 phase->intcon(con1), T_INT);
3468 }
3469 }
3470
3471 // Insert second store first, then the first before the second.
3472 // Insert each one just before any overlapping non-constant stores.
3473 while (nst > 0) {
3474 Node* st1 = st[--nst];
3475 C->copy_node_notes_to(st1, old);
3476 st1 = phase->transform(st1);
3477 offset = off[nst];
3478 assert(offset >= header_size, "do not smash header");
3479 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3480 guarantee(ins_idx != 0, "must re-insert constant store");
3481 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3482 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3483 set_req(--ins_idx, st1);
3484 else
3485 ins_req(ins_idx, st1);
3486 }
3487 }
3488
3489 if (PrintCompilation && WizardMode)
3490 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3491 old_subword, old_long, new_int, new_long);
3492 if (C->log() != NULL)
3493 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3494 old_subword, old_long, new_int, new_long);
3495
3496 // Clean up any remaining occurrences of zmem:
3497 remove_extra_zeroes();
3498 }
3499
3500 // Explore forward from in(start) to find the first fully initialized
3501 // word, and return its offset. Skip groups of subword stores which
3502 // together initialize full words. If in(start) is itself part of a
3503 // fully initialized word, return the offset of in(start). If there
3504 // are no following full-word stores, or if something is fishy, return
3505 // a negative value.
3506 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3507 int int_map = 0;
3508 intptr_t int_map_off = 0;
3509 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3510
3511 for (uint i = start, limit = req(); i < limit; i++) {
3512 Node* st = in(i);
3513
3514 intptr_t st_off = get_store_offset(st, phase);
3515 if (st_off < 0) break; // return conservative answer
3516
3517 int st_size = st->as_Store()->memory_size();
3518 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3519 return st_off; // we found a complete word init
3520 }
3521
3522 // update the map:
3523
3524 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3525 if (this_int_off != int_map_off) {
3526 // reset the map:
3527 int_map = 0;
3528 int_map_off = this_int_off;
3529 }
3530
3531 int subword_off = st_off - this_int_off;
3532 int_map |= right_n_bits(st_size) << subword_off;
3533 if ((int_map & FULL_MAP) == FULL_MAP) {
3534 return this_int_off; // we found a complete word init
3535 }
3536
3537 // Did this store hit or cross the word boundary?
3538 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3539 if (next_int_off == this_int_off + BytesPerInt) {
3540 // We passed the current int, without fully initializing it.
3541 int_map_off = next_int_off;
3542 int_map >>= BytesPerInt;
3543 } else if (next_int_off > this_int_off + BytesPerInt) {
3544 // We passed the current and next int.
3545 return this_int_off + BytesPerInt;
3546 }
3547 }
3548
3549 return -1;
3550 }
3551
3552
3553 // Called when the associated AllocateNode is expanded into CFG.
3554 // At this point, we may perform additional optimizations.
3555 // Linearize the stores by ascending offset, to make memory
3556 // activity as coherent as possible.
3557 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3558 intptr_t header_size,
3559 Node* size_in_bytes,
3560 PhaseGVN* phase) {
3561 assert(!is_complete(), "not already complete");
3562 assert(stores_are_sane(phase), "");
3563 assert(allocation() != NULL, "must be present");
3564
3565 remove_extra_zeroes();
3566
3567 if (ReduceFieldZeroing || ReduceBulkZeroing)
3568 // reduce instruction count for common initialization patterns
3569 coalesce_subword_stores(header_size, size_in_bytes, phase);
3570
3571 Node* zmem = zero_memory(); // initially zero memory state
3572 Node* inits = zmem; // accumulating a linearized chain of inits
3573 #ifdef ASSERT
3574 intptr_t first_offset = allocation()->minimum_header_size();
3575 intptr_t last_init_off = first_offset; // previous init offset
3576 intptr_t last_init_end = first_offset; // previous init offset+size
3577 intptr_t last_tile_end = first_offset; // previous tile offset+size
3578 #endif
3579 intptr_t zeroes_done = header_size;
3580
3581 bool do_zeroing = true; // we might give up if inits are very sparse
3582 int big_init_gaps = 0; // how many large gaps have we seen?
3583
3584 if (ZeroTLAB) do_zeroing = false;
3585 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3586
3587 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3588 Node* st = in(i);
3589 intptr_t st_off = get_store_offset(st, phase);
3590 if (st_off < 0)
3591 break; // unknown junk in the inits
3592 if (st->in(MemNode::Memory) != zmem)
3593 break; // complicated store chains somehow in list
3594
3595 int st_size = st->as_Store()->memory_size();
3596 intptr_t next_init_off = st_off + st_size;
3597
3598 if (do_zeroing && zeroes_done < next_init_off) {
3599 // See if this store needs a zero before it or under it.
3600 intptr_t zeroes_needed = st_off;
3601
3602 if (st_size < BytesPerInt) {
3603 // Look for subword stores which only partially initialize words.
3604 // If we find some, we must lay down some word-level zeroes first,
3605 // underneath the subword stores.
3606 //
3607 // Examples:
3608 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3609 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3610 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3611 //
3612 // Note: coalesce_subword_stores may have already done this,
3613 // if it was prompted by constant non-zero subword initializers.
3614 // But this case can still arise with non-constant stores.
3615
3616 intptr_t next_full_store = find_next_fullword_store(i, phase);
3617
3618 // In the examples above:
3619 // in(i) p q r s x y z
3620 // st_off 12 13 14 15 12 13 14
3621 // st_size 1 1 1 1 1 1 1
3622 // next_full_s. 12 16 16 16 16 16 16
3623 // z's_done 12 16 16 16 12 16 12
3624 // z's_needed 12 16 16 16 16 16 16
3625 // zsize 0 0 0 0 4 0 4
3626 if (next_full_store < 0) {
3627 // Conservative tack: Zero to end of current word.
3628 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3629 } else {
3630 // Zero to beginning of next fully initialized word.
3631 // Or, don't zero at all, if we are already in that word.
3632 assert(next_full_store >= zeroes_needed, "must go forward");
3633 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3634 zeroes_needed = next_full_store;
3635 }
3636 }
3637
3638 if (zeroes_needed > zeroes_done) {
3639 intptr_t zsize = zeroes_needed - zeroes_done;
3640 // Do some incremental zeroing on rawmem, in parallel with inits.
3641 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3642 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3643 zeroes_done, zeroes_needed,
3644 phase);
3645 zeroes_done = zeroes_needed;
3646 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3647 do_zeroing = false; // leave the hole, next time
3648 }
3649 }
3650
3651 // Collect the store and move on:
3652 st->set_req(MemNode::Memory, inits);
3653 inits = st; // put it on the linearized chain
3654 set_req(i, zmem); // unhook from previous position
3655
3656 if (zeroes_done == st_off)
3657 zeroes_done = next_init_off;
3658
3659 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3660
3661 #ifdef ASSERT
3662 // Various order invariants. Weaker than stores_are_sane because
3663 // a large constant tile can be filled in by smaller non-constant stores.
3664 assert(st_off >= last_init_off, "inits do not reverse");
3665 last_init_off = st_off;
3666 const Type* val = NULL;
3667 if (st_size >= BytesPerInt &&
3668 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3669 (int)val->basic_type() < (int)T_OBJECT) {
3670 assert(st_off >= last_tile_end, "tiles do not overlap");
3671 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3672 last_tile_end = MAX2(last_tile_end, next_init_off);
3673 } else {
3674 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3675 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3676 assert(st_off >= last_init_end, "inits do not overlap");
3677 last_init_end = next_init_off; // it's a non-tile
3678 }
3679 #endif //ASSERT
3680 }
3681
3682 remove_extra_zeroes(); // clear out all the zmems left over
3683 add_req(inits);
3684
3685 if (!ZeroTLAB) {
3686 // If anything remains to be zeroed, zero it all now.
3687 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3688 // if it is the last unused 4 bytes of an instance, forget about it
3689 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3690 if (zeroes_done + BytesPerLong >= size_limit) {
3691 assert(allocation() != NULL, "");
3692 if (allocation()->Opcode() == Op_Allocate) {
3693 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3694 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3695 if (zeroes_done == k->layout_helper())
3696 zeroes_done = size_limit;
3697 }
3698 }
3699 if (zeroes_done < size_limit) {
3700 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3701 zeroes_done, size_in_bytes, phase);
3702 }
3703 }
3704
3705 set_complete(phase);
3706 return rawmem;
3707 }
3708
3709
3710 #ifdef ASSERT
3711 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3712 if (is_complete())
3713 return true; // stores could be anything at this point
3714 assert(allocation() != NULL, "must be present");
3715 intptr_t last_off = allocation()->minimum_header_size();
3716 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3717 Node* st = in(i);
3718 intptr_t st_off = get_store_offset(st, phase);
3719 if (st_off < 0) continue; // ignore dead garbage
3720 if (last_off > st_off) {
3721 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3722 this->dump(2);
3723 assert(false, "ascending store offsets");
3724 return false;
3725 }
3726 last_off = st_off + st->as_Store()->memory_size();
3727 }
3728 return true;
3729 }
3730 #endif //ASSERT
3731
3732
3733
3734
3735 //============================MergeMemNode=====================================
3736 //
3737 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3738 // contributing store or call operations. Each contributor provides the memory
3739 // state for a particular "alias type" (see Compile::alias_type). For example,
3740 // if a MergeMem has an input X for alias category #6, then any memory reference
3741 // to alias category #6 may use X as its memory state input, as an exact equivalent
3742 // to using the MergeMem as a whole.
3743 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3744 //
3745 // (Here, the <N> notation gives the index of the relevant adr_type.)
3746 //
3747 // In one special case (and more cases in the future), alias categories overlap.
3748 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3749 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3750 // it is exactly equivalent to that state W:
3751 // MergeMem(<Bot>: W) <==> W
3752 //
3753 // Usually, the merge has more than one input. In that case, where inputs
3754 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3755 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3756 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3757 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3758 //
3759 // A merge can take a "wide" memory state as one of its narrow inputs.
3760 // This simply means that the merge observes out only the relevant parts of
3761 // the wide input. That is, wide memory states arriving at narrow merge inputs
3762 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3763 //
3764 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3765 // and that memory slices "leak through":
3766 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3767 //
3768 // But, in such a cascade, repeated memory slices can "block the leak":
3769 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3770 //
3771 // In the last example, Y is not part of the combined memory state of the
3772 // outermost MergeMem. The system must, of course, prevent unschedulable
3773 // memory states from arising, so you can be sure that the state Y is somehow
3774 // a precursor to state Y'.
3775 //
3776 //
3777 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3778 // of each MergeMemNode array are exactly the numerical alias indexes, including
3779 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3780 // Compile::alias_type (and kin) produce and manage these indexes.
3781 //
3782 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3783 // (Note that this provides quick access to the top node inside MergeMem methods,
3784 // without the need to reach out via TLS to Compile::current.)
3785 //
3786 // As a consequence of what was just described, a MergeMem that represents a full
3787 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3788 // containing all alias categories.
3789 //
3790 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3791 //
3792 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3793 // a memory state for the alias type <N>, or else the top node, meaning that
3794 // there is no particular input for that alias type. Note that the length of
3795 // a MergeMem is variable, and may be extended at any time to accommodate new
3796 // memory states at larger alias indexes. When merges grow, they are of course
3797 // filled with "top" in the unused in() positions.
3798 //
3799 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3800 // (Top was chosen because it works smoothly with passes like GCM.)
3801 //
3802 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3803 // the type of random VM bits like TLS references.) Since it is always the
3804 // first non-Bot memory slice, some low-level loops use it to initialize an
3805 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3806 //
3807 //
3808 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3809 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3810 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3811 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3812 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3813 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3814 //
3815 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3816 // really that different from the other memory inputs. An abbreviation called
3817 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3818 //
3819 //
3820 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3821 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3822 // that "emerges though" the base memory will be marked as excluding the alias types
3823 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3824 //
3825 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3826 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3827 //
3828 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3829 // (It is currently unimplemented.) As you can see, the resulting merge is
3830 // actually a disjoint union of memory states, rather than an overlay.
3831 //
3832
3833 //------------------------------MergeMemNode-----------------------------------
3834 Node* MergeMemNode::make_empty_memory() {
3835 Node* empty_memory = (Node*) Compile::current()->top();
3836 assert(empty_memory->is_top(), "correct sentinel identity");
3837 return empty_memory;
3838 }
3839
3840 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3841 init_class_id(Class_MergeMem);
3842 // all inputs are nullified in Node::Node(int)
3843 // set_input(0, NULL); // no control input
3844
3845 // Initialize the edges uniformly to top, for starters.
3846 Node* empty_mem = make_empty_memory();
3847 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3848 init_req(i,empty_mem);
3849 }
3850 assert(empty_memory() == empty_mem, "");
3851
3852 if( new_base != NULL && new_base->is_MergeMem() ) {
3853 MergeMemNode* mdef = new_base->as_MergeMem();
3854 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3855 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3856 mms.set_memory(mms.memory2());
3857 }
3858 assert(base_memory() == mdef->base_memory(), "");
3859 } else {
3860 set_base_memory(new_base);
3861 }
3862 }
3863
3864 // Make a new, untransformed MergeMem with the same base as 'mem'.
3865 // If mem is itself a MergeMem, populate the result with the same edges.
3866 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3867 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3868 }
3869
3870 //------------------------------cmp--------------------------------------------
3871 uint MergeMemNode::hash() const { return NO_HASH; }
3872 uint MergeMemNode::cmp( const Node &n ) const {
3873 return (&n == this); // Always fail except on self
3874 }
3875
3876 //------------------------------Identity---------------------------------------
3877 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3878 // Identity if this merge point does not record any interesting memory
3879 // disambiguations.
3880 Node* base_mem = base_memory();
3881 Node* empty_mem = empty_memory();
3882 if (base_mem != empty_mem) { // Memory path is not dead?
3883 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3884 Node* mem = in(i);
3885 if (mem != empty_mem && mem != base_mem) {
3886 return this; // Many memory splits; no change
3887 }
3888 }
3889 }
3890 return base_mem; // No memory splits; ID on the one true input
3891 }
3892
3893 //------------------------------Ideal------------------------------------------
3894 // This method is invoked recursively on chains of MergeMem nodes
3895 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3896 // Remove chain'd MergeMems
3897 //
3898 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3899 // relative to the "in(Bot)". Since we are patching both at the same time,
3900 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3901 // but rewrite each "in(i)" relative to the new "in(Bot)".
3902 Node *progress = NULL;
3903
3904
3905 Node* old_base = base_memory();
3906 Node* empty_mem = empty_memory();
3907 if (old_base == empty_mem)
3908 return NULL; // Dead memory path.
3909
3910 MergeMemNode* old_mbase;
3911 if (old_base != NULL && old_base->is_MergeMem())
3912 old_mbase = old_base->as_MergeMem();
3913 else
3914 old_mbase = NULL;
3915 Node* new_base = old_base;
3916
3917 // simplify stacked MergeMems in base memory
3918 if (old_mbase) new_base = old_mbase->base_memory();
3919
3920 // the base memory might contribute new slices beyond my req()
3921 if (old_mbase) grow_to_match(old_mbase);
3922
3923 // Look carefully at the base node if it is a phi.
3924 PhiNode* phi_base;
3925 if (new_base != NULL && new_base->is_Phi())
3926 phi_base = new_base->as_Phi();
3927 else
3928 phi_base = NULL;
3929
3930 Node* phi_reg = NULL;
3931 uint phi_len = (uint)-1;
3932 if (phi_base != NULL && !phi_base->is_copy()) {
3933 // do not examine phi if degraded to a copy
3934 phi_reg = phi_base->region();
3935 phi_len = phi_base->req();
3936 // see if the phi is unfinished
3937 for (uint i = 1; i < phi_len; i++) {
3938 if (phi_base->in(i) == NULL) {
3939 // incomplete phi; do not look at it yet!
3940 phi_reg = NULL;
3941 phi_len = (uint)-1;
3942 break;
3943 }
3944 }
3945 }
3946
3947 // Note: We do not call verify_sparse on entry, because inputs
3948 // can normalize to the base_memory via subsume_node or similar
3949 // mechanisms. This method repairs that damage.
3950
3951 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3952
3953 // Look at each slice.
3954 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3955 Node* old_in = in(i);
3956 // calculate the old memory value
3957 Node* old_mem = old_in;
3958 if (old_mem == empty_mem) old_mem = old_base;
3959 assert(old_mem == memory_at(i), "");
3960
3961 // maybe update (reslice) the old memory value
3962
3963 // simplify stacked MergeMems
3964 Node* new_mem = old_mem;
3965 MergeMemNode* old_mmem;
3966 if (old_mem != NULL && old_mem->is_MergeMem())
3967 old_mmem = old_mem->as_MergeMem();
3968 else
3969 old_mmem = NULL;
3970 if (old_mmem == this) {
3971 // This can happen if loops break up and safepoints disappear.
3972 // A merge of BotPtr (default) with a RawPtr memory derived from a
3973 // safepoint can be rewritten to a merge of the same BotPtr with
3974 // the BotPtr phi coming into the loop. If that phi disappears
3975 // also, we can end up with a self-loop of the mergemem.
3976 // In general, if loops degenerate and memory effects disappear,
3977 // a mergemem can be left looking at itself. This simply means
3978 // that the mergemem's default should be used, since there is
3979 // no longer any apparent effect on this slice.
3980 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3981 // from start. Update the input to TOP.
3982 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3983 }
3984 else if (old_mmem != NULL) {
3985 new_mem = old_mmem->memory_at(i);
3986 }
3987 // else preceding memory was not a MergeMem
3988
3989 // replace equivalent phis (unfortunately, they do not GVN together)
3990 if (new_mem != NULL && new_mem != new_base &&
3991 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3992 if (new_mem->is_Phi()) {
3993 PhiNode* phi_mem = new_mem->as_Phi();
3994 for (uint i = 1; i < phi_len; i++) {
3995 if (phi_base->in(i) != phi_mem->in(i)) {
3996 phi_mem = NULL;
3997 break;
3998 }
3999 }
4000 if (phi_mem != NULL) {
4001 // equivalent phi nodes; revert to the def
4002 new_mem = new_base;
4003 }
4004 }
4005 }
4006
4007 // maybe store down a new value
4008 Node* new_in = new_mem;
4009 if (new_in == new_base) new_in = empty_mem;
4010
4011 if (new_in != old_in) {
4012 // Warning: Do not combine this "if" with the previous "if"
4013 // A memory slice might have be be rewritten even if it is semantically
4014 // unchanged, if the base_memory value has changed.
4015 set_req(i, new_in);
4016 progress = this; // Report progress
4017 }
4018 }
4019
4020 if (new_base != old_base) {
4021 set_req(Compile::AliasIdxBot, new_base);
4022 // Don't use set_base_memory(new_base), because we need to update du.
4023 assert(base_memory() == new_base, "");
4024 progress = this;
4025 }
4026
4027 if( base_memory() == this ) {
4028 // a self cycle indicates this memory path is dead
4029 set_req(Compile::AliasIdxBot, empty_mem);
4030 }
4031
4032 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4033 // Recursion must occur after the self cycle check above
4034 if( base_memory()->is_MergeMem() ) {
4035 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4036 Node *m = phase->transform(new_mbase); // Rollup any cycles
4037 if( m != NULL && (m->is_top() ||
4038 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4039 // propagate rollup of dead cycle to self
4040 set_req(Compile::AliasIdxBot, empty_mem);
4041 }
4042 }
4043
4044 if( base_memory() == empty_mem ) {
4045 progress = this;
4046 // Cut inputs during Parse phase only.
4047 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4048 if( !can_reshape ) {
4049 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4050 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4051 }
4052 }
4053 }
4054
4055 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4056 // Check if PhiNode::Ideal's "Split phis through memory merges"
4057 // transform should be attempted. Look for this->phi->this cycle.
4058 uint merge_width = req();
4059 if (merge_width > Compile::AliasIdxRaw) {
4060 PhiNode* phi = base_memory()->as_Phi();
4061 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4062 if (phi->in(i) == this) {
4063 phase->is_IterGVN()->_worklist.push(phi);
4064 break;
4065 }
4066 }
4067 }
4068 }
4069
4070 assert(progress || verify_sparse(), "please, no dups of base");
4071 return progress;
4072 }
4073
4074 //-------------------------set_base_memory-------------------------------------
4075 void MergeMemNode::set_base_memory(Node *new_base) {
4076 Node* empty_mem = empty_memory();
4077 set_req(Compile::AliasIdxBot, new_base);
4078 assert(memory_at(req()) == new_base, "must set default memory");
4079 // Clear out other occurrences of new_base:
4080 if (new_base != empty_mem) {
4081 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4082 if (in(i) == new_base) set_req(i, empty_mem);
4083 }
4084 }
4085 }
4086
4087 //------------------------------out_RegMask------------------------------------
4088 const RegMask &MergeMemNode::out_RegMask() const {
4089 return RegMask::Empty;
4090 }
4091
4092 //------------------------------dump_spec--------------------------------------
4093 #ifndef PRODUCT
4094 void MergeMemNode::dump_spec(outputStream *st) const {
4095 st->print(" {");
4096 Node* base_mem = base_memory();
4097 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4098 Node* mem = memory_at(i);
4099 if (mem == base_mem) { st->print(" -"); continue; }
4100 st->print( " N%d:", mem->_idx );
4101 Compile::current()->get_adr_type(i)->dump_on(st);
4102 }
4103 st->print(" }");
4104 }
4105 #endif // !PRODUCT
4106
4107
4108 #ifdef ASSERT
4109 static bool might_be_same(Node* a, Node* b) {
4110 if (a == b) return true;
4111 if (!(a->is_Phi() || b->is_Phi())) return false;
4112 // phis shift around during optimization
4113 return true; // pretty stupid...
4114 }
4115
4116 // verify a narrow slice (either incoming or outgoing)
4117 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4118 if (!VerifyAliases) return; // don't bother to verify unless requested
4119 if (is_error_reported()) return; // muzzle asserts when debugging an error
4120 if (Node::in_dump()) return; // muzzle asserts when printing
4121 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4122 assert(n != NULL, "");
4123 // Elide intervening MergeMem's
4124 while (n->is_MergeMem()) {
4125 n = n->as_MergeMem()->memory_at(alias_idx);
4126 }
4127 Compile* C = Compile::current();
4128 const TypePtr* n_adr_type = n->adr_type();
4129 if (n == m->empty_memory()) {
4130 // Implicit copy of base_memory()
4131 } else if (n_adr_type != TypePtr::BOTTOM) {
4132 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4133 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4134 } else {
4135 // A few places like make_runtime_call "know" that VM calls are narrow,
4136 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4137 bool expected_wide_mem = false;
4138 if (n == m->base_memory()) {
4139 expected_wide_mem = true;
4140 } else if (alias_idx == Compile::AliasIdxRaw ||
4141 n == m->memory_at(Compile::AliasIdxRaw)) {
4142 expected_wide_mem = true;
4143 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4144 // memory can "leak through" calls on channels that
4145 // are write-once. Allow this also.
4146 expected_wide_mem = true;
4147 }
4148 assert(expected_wide_mem, "expected narrow slice replacement");
4149 }
4150 }
4151 #else // !ASSERT
4152 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4153 #endif
4154
4155
4156 //-----------------------------memory_at---------------------------------------
4157 Node* MergeMemNode::memory_at(uint alias_idx) const {
4158 assert(alias_idx >= Compile::AliasIdxRaw ||
4159 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4160 "must avoid base_memory and AliasIdxTop");
4161
4162 // Otherwise, it is a narrow slice.
4163 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4164 Compile *C = Compile::current();
4165 if (is_empty_memory(n)) {
4166 // the array is sparse; empty slots are the "top" node
4167 n = base_memory();
4168 assert(Node::in_dump()
4169 || n == NULL || n->bottom_type() == Type::TOP
4170 || n->adr_type() == NULL // address is TOP
4171 || n->adr_type() == TypePtr::BOTTOM
4172 || n->adr_type() == TypeRawPtr::BOTTOM
4173 || Compile::current()->AliasLevel() == 0,
4174 "must be a wide memory");
4175 // AliasLevel == 0 if we are organizing the memory states manually.
4176 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4177 } else {
4178 // make sure the stored slice is sane
4179 #ifdef ASSERT
4180 if (is_error_reported() || Node::in_dump()) {
4181 } else if (might_be_same(n, base_memory())) {
4182 // Give it a pass: It is a mostly harmless repetition of the base.
4183 // This can arise normally from node subsumption during optimization.
4184 } else {
4185 verify_memory_slice(this, alias_idx, n);
4186 }
4187 #endif
4188 }
4189 return n;
4190 }
4191
4192 //---------------------------set_memory_at-------------------------------------
4193 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4194 verify_memory_slice(this, alias_idx, n);
4195 Node* empty_mem = empty_memory();
4196 if (n == base_memory()) n = empty_mem; // collapse default
4197 uint need_req = alias_idx+1;
4198 if (req() < need_req) {
4199 if (n == empty_mem) return; // already the default, so do not grow me
4200 // grow the sparse array
4201 do {
4202 add_req(empty_mem);
4203 } while (req() < need_req);
4204 }
4205 set_req( alias_idx, n );
4206 }
4207
4208
4209
4210 //--------------------------iteration_setup------------------------------------
4211 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4212 if (other != NULL) {
4213 grow_to_match(other);
4214 // invariant: the finite support of mm2 is within mm->req()
4215 #ifdef ASSERT
4216 for (uint i = req(); i < other->req(); i++) {
4217 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4218 }
4219 #endif
4220 }
4221 // Replace spurious copies of base_memory by top.
4222 Node* base_mem = base_memory();
4223 if (base_mem != NULL && !base_mem->is_top()) {
4224 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4225 if (in(i) == base_mem)
4226 set_req(i, empty_memory());
4227 }
4228 }
4229 }
4230
4231 //---------------------------grow_to_match-------------------------------------
4232 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4233 Node* empty_mem = empty_memory();
4234 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4235 // look for the finite support of the other memory
4236 for (uint i = other->req(); --i >= req(); ) {
4237 if (other->in(i) != empty_mem) {
4238 uint new_len = i+1;
4239 while (req() < new_len) add_req(empty_mem);
4240 break;
4241 }
4242 }
4243 }
4244
4245 //---------------------------verify_sparse-------------------------------------
4246 #ifndef PRODUCT
4247 bool MergeMemNode::verify_sparse() const {
4248 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4249 Node* base_mem = base_memory();
4250 // The following can happen in degenerate cases, since empty==top.
4251 if (is_empty_memory(base_mem)) return true;
4252 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4253 assert(in(i) != NULL, "sane slice");
4254 if (in(i) == base_mem) return false; // should have been the sentinel value!
4255 }
4256 return true;
4257 }
4258
4259 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4260 Node* n;
4261 n = mm->in(idx);
4262 if (mem == n) return true; // might be empty_memory()
4263 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4264 if (mem == n) return true;
4265 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4266 if (mem == n) return true;
4267 if (n == NULL) break;
4268 }
4269 return false;
4270 }
4271 #endif // !PRODUCT