Sat, 01 Sep 2012 13:25:18 -0400
6964458: Reimplement class meta-data storage to use native memory
Summary: Remove PermGen, allocate meta-data in metaspace linked to class loaders, rewrite GC walking, rewrite and rename metadata to be C++ classes
Reviewed-by: jmasa, stefank, never, coleenp, kvn, brutisso, mgerdin, dholmes, jrose, twisti, roland
Contributed-by: jmasa <jon.masamitsu@oracle.com>, stefank <stefan.karlsson@oracle.com>, mgerdin <mikael.gerdin@oracle.com>, never <tom.rodriguez@oracle.com>
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 */
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"
42 // Portions of code courtesy of Clifford Click
44 // Optimization - Graph Style
46 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
48 //=============================================================================
49 uint MemNode::size_of() const { return sizeof(*this); }
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 }
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);
69 Compile* C = Compile::current();
70 if( C->alias_type(_adr_type)->is_volatile() )
71 st->print(" Volatile!");
72 }
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 }
102 extern void print_alias_types();
104 #endif
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 }
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 }
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 }
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;
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" );
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 }
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
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 }
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 }
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
303 // Avoid independent memory operations
304 Node* old_mem = mem;
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().
314 if (mem->is_MergeMem()) {
315 MergeMemNode* mmem = mem->as_MergeMem();
316 const TypePtr *tp = t_adr->is_ptr();
318 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
319 }
321 if (mem != old_mem) {
322 set_req(MemNode::Memory, mem);
323 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
324 return this;
325 }
327 // let the subclass continue analyzing...
328 return NULL;
329 }
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
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
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 }
353 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
354 return true;
356 // 'dom' dominates 'sub' if its control edge and control edges
357 // of all its inputs dominate or equal to sub's control edge.
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");
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
371 assert(sub->is_CFG(), "expecting control");
373 if (sub == dom)
374 return true;
376 if (sub->is_Start() || sub->is_Root())
377 return false;
379 {
380 // Check all control edges of 'dom'.
382 ResourceMark rm;
383 Arena* arena = Thread::current()->resource_area();
384 Node_List nlist(arena);
385 Unique_Node_List dom_list(arena);
387 dom_list.push(dom);
388 bool only_dominating_controls = false;
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 }
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 }
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);
476 if (offset == Type::OffsetBot)
477 return NULL; // cannot unalias unless there are precise offsets
479 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
481 intptr_t size_in_bytes = memory_size();
483 Node* mem = in(MemNode::Memory); // start searching here...
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?
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 }
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 }
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;
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 }
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 }
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 }
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 }
591 return NULL; // bail out
592 }
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 }
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;
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));
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 }
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 }
680 // Quit when the worklist is empty, and we've found no offending nodes.
681 return true;
682 }
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 }
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() ) {
712 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
713 adr = adr->in(AddPNode::Base);
714 continue;
716 case Op_DecodeN: // No change to NULL-ness, so peek thru
717 adr = adr->in(1);
718 continue;
720 case Op_EncodeP:
721 // EncodeP node's control edge could be set by this method
722 // when EncodeP node depends on CastPP node.
723 //
724 // Use its control edge for memory op because EncodeP may go away
725 // later when it is folded with following or preceding DecodeN node.
726 if (adr->in(0) == NULL) {
727 // Keep looking for cast nodes.
728 adr = adr->in(1);
729 continue;
730 }
731 ccp->hash_delete(n);
732 n->set_req(MemNode::Control, adr->in(0));
733 ccp->hash_insert(n);
734 return n;
736 case Op_CastPP:
737 // If the CastPP is useless, just peek on through it.
738 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
739 // Remember the cast that we've peeked though. If we peek
740 // through more than one, then we end up remembering the highest
741 // one, that is, if in a loop, the one closest to the top.
742 skipped_cast = adr;
743 adr = adr->in(1);
744 continue;
745 }
746 // CastPP is going away in this pass! We need this memory op to be
747 // control-dependent on the test that is guarding the CastPP.
748 ccp->hash_delete(n);
749 n->set_req(MemNode::Control, adr->in(0));
750 ccp->hash_insert(n);
751 return n;
753 case Op_Phi:
754 // Attempt to float above a Phi to some dominating point.
755 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
756 // If we've already peeked through a Cast (which could have set the
757 // control), we can't float above a Phi, because the skipped Cast
758 // may not be loop invariant.
759 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
760 adr = adr->in(1);
761 continue;
762 }
763 }
765 // Intentional fallthrough!
767 // No obvious dominating point. The mem op is pinned below the Phi
768 // by the Phi itself. If the Phi goes away (no true value is merged)
769 // then the mem op can float, but not indefinitely. It must be pinned
770 // behind the controls leading to the Phi.
771 case Op_CheckCastPP:
772 // These usually stick around to change address type, however a
773 // useless one can be elided and we still need to pick up a control edge
774 if (adr->in(0) == NULL) {
775 // This CheckCastPP node has NO control and is likely useless. But we
776 // need check further up the ancestor chain for a control input to keep
777 // the node in place. 4959717.
778 skipped_cast = adr;
779 adr = adr->in(1);
780 continue;
781 }
782 ccp->hash_delete(n);
783 n->set_req(MemNode::Control, adr->in(0));
784 ccp->hash_insert(n);
785 return n;
787 // List of "safe" opcodes; those that implicitly block the memory
788 // op below any null check.
789 case Op_CastX2P: // no null checks on native pointers
790 case Op_Parm: // 'this' pointer is not null
791 case Op_LoadP: // Loading from within a klass
792 case Op_LoadN: // Loading from within a klass
793 case Op_LoadKlass: // Loading from within a klass
794 case Op_LoadNKlass: // Loading from within a klass
795 case Op_ConP: // Loading from a klass
796 case Op_ConN: // Loading from a klass
797 case Op_CreateEx: // Sucking up the guts of an exception oop
798 case Op_Con: // Reading from TLS
799 case Op_CMoveP: // CMoveP is pinned
800 case Op_CMoveN: // CMoveN is pinned
801 break; // No progress
803 case Op_Proj: // Direct call to an allocation routine
804 case Op_SCMemProj: // Memory state from store conditional ops
805 #ifdef ASSERT
806 {
807 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
808 const Node* call = adr->in(0);
809 if (call->is_CallJava()) {
810 const CallJavaNode* call_java = call->as_CallJava();
811 const TypeTuple *r = call_java->tf()->range();
812 assert(r->cnt() > TypeFunc::Parms, "must return value");
813 const Type* ret_type = r->field_at(TypeFunc::Parms);
814 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
815 // We further presume that this is one of
816 // new_instance_Java, new_array_Java, or
817 // the like, but do not assert for this.
818 } else if (call->is_Allocate()) {
819 // similar case to new_instance_Java, etc.
820 } else if (!call->is_CallLeaf()) {
821 // Projections from fetch_oop (OSR) are allowed as well.
822 ShouldNotReachHere();
823 }
824 }
825 #endif
826 break;
827 default:
828 ShouldNotReachHere();
829 }
830 break;
831 }
832 }
834 return NULL; // No progress
835 }
838 //=============================================================================
839 uint LoadNode::size_of() const { return sizeof(*this); }
840 uint LoadNode::cmp( const Node &n ) const
841 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
842 const Type *LoadNode::bottom_type() const { return _type; }
843 uint LoadNode::ideal_reg() const {
844 return _type->ideal_reg();
845 }
847 #ifndef PRODUCT
848 void LoadNode::dump_spec(outputStream *st) const {
849 MemNode::dump_spec(st);
850 if( !Verbose && !WizardMode ) {
851 // standard dump does this in Verbose and WizardMode
852 st->print(" #"); _type->dump_on(st);
853 }
854 }
855 #endif
857 #ifdef ASSERT
858 //----------------------------is_immutable_value-------------------------------
859 // Helper function to allow a raw load without control edge for some cases
860 bool LoadNode::is_immutable_value(Node* adr) {
861 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
862 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
863 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
864 in_bytes(JavaThread::osthread_offset())));
865 }
866 #endif
868 //----------------------------LoadNode::make-----------------------------------
869 // Polymorphic factory method:
870 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
871 Compile* C = gvn.C;
873 // sanity check the alias category against the created node type
874 assert(!(adr_type->isa_oopptr() &&
875 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
876 "use LoadKlassNode instead");
877 assert(!(adr_type->isa_aryptr() &&
878 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
879 "use LoadRangeNode instead");
880 // Check control edge of raw loads
881 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
882 // oop will be recorded in oop map if load crosses safepoint
883 rt->isa_oopptr() || is_immutable_value(adr),
884 "raw memory operations should have control edge");
885 switch (bt) {
886 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
887 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
888 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
889 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
890 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
891 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
892 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
893 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
894 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
895 case T_OBJECT:
896 #ifdef _LP64
897 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
898 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
899 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
900 } else
901 #endif
902 {
903 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
904 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
905 }
906 }
907 ShouldNotReachHere();
908 return (LoadNode*)NULL;
909 }
911 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
912 bool require_atomic = true;
913 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
914 }
919 //------------------------------hash-------------------------------------------
920 uint LoadNode::hash() const {
921 // unroll addition of interesting fields
922 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
923 }
925 //---------------------------can_see_stored_value------------------------------
926 // This routine exists to make sure this set of tests is done the same
927 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
928 // will change the graph shape in a way which makes memory alive twice at the
929 // same time (uses the Oracle model of aliasing), then some
930 // LoadXNode::Identity will fold things back to the equivalence-class model
931 // of aliasing.
932 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
933 Node* ld_adr = in(MemNode::Address);
935 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
936 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
937 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
938 atp->field() != NULL && !atp->field()->is_volatile()) {
939 uint alias_idx = atp->index();
940 bool final = atp->field()->is_final();
941 Node* result = NULL;
942 Node* current = st;
943 // Skip through chains of MemBarNodes checking the MergeMems for
944 // new states for the slice of this load. Stop once any other
945 // kind of node is encountered. Loads from final memory can skip
946 // through any kind of MemBar but normal loads shouldn't skip
947 // through MemBarAcquire since the could allow them to move out of
948 // a synchronized region.
949 while (current->is_Proj()) {
950 int opc = current->in(0)->Opcode();
951 if ((final && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock)) ||
952 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder ||
953 opc == Op_MemBarReleaseLock) {
954 Node* mem = current->in(0)->in(TypeFunc::Memory);
955 if (mem->is_MergeMem()) {
956 MergeMemNode* merge = mem->as_MergeMem();
957 Node* new_st = merge->memory_at(alias_idx);
958 if (new_st == merge->base_memory()) {
959 // Keep searching
960 current = merge->base_memory();
961 continue;
962 }
963 // Save the new memory state for the slice and fall through
964 // to exit.
965 result = new_st;
966 }
967 }
968 break;
969 }
970 if (result != NULL) {
971 st = result;
972 }
973 }
976 // Loop around twice in the case Load -> Initialize -> Store.
977 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
978 for (int trip = 0; trip <= 1; trip++) {
980 if (st->is_Store()) {
981 Node* st_adr = st->in(MemNode::Address);
982 if (!phase->eqv(st_adr, ld_adr)) {
983 // Try harder before giving up... Match raw and non-raw pointers.
984 intptr_t st_off = 0;
985 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
986 if (alloc == NULL) return NULL;
987 intptr_t ld_off = 0;
988 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
989 if (alloc != allo2) return NULL;
990 if (ld_off != st_off) return NULL;
991 // At this point we have proven something like this setup:
992 // A = Allocate(...)
993 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
994 // S = StoreQ(, AddP(, A.Parm , #Off), V)
995 // (Actually, we haven't yet proven the Q's are the same.)
996 // In other words, we are loading from a casted version of
997 // the same pointer-and-offset that we stored to.
998 // Thus, we are able to replace L by V.
999 }
1000 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1001 if (store_Opcode() != st->Opcode())
1002 return NULL;
1003 return st->in(MemNode::ValueIn);
1004 }
1006 intptr_t offset = 0; // scratch
1008 // A load from a freshly-created object always returns zero.
1009 // (This can happen after LoadNode::Ideal resets the load's memory input
1010 // to find_captured_store, which returned InitializeNode::zero_memory.)
1011 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1012 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
1013 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
1014 // return a zero value for the load's basic type
1015 // (This is one of the few places where a generic PhaseTransform
1016 // can create new nodes. Think of it as lazily manifesting
1017 // virtually pre-existing constants.)
1018 return phase->zerocon(memory_type());
1019 }
1021 // A load from an initialization barrier can match a captured store.
1022 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1023 InitializeNode* init = st->in(0)->as_Initialize();
1024 AllocateNode* alloc = init->allocation();
1025 if (alloc != NULL &&
1026 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1027 // examine a captured store value
1028 st = init->find_captured_store(offset, memory_size(), phase);
1029 if (st != NULL)
1030 continue; // take one more trip around
1031 }
1032 }
1034 break;
1035 }
1037 return NULL;
1038 }
1040 //----------------------is_instance_field_load_with_local_phi------------------
1041 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1042 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1043 in(MemNode::Address)->is_AddP() ) {
1044 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1045 // Only instances.
1046 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1047 t_oop->offset() != Type::OffsetBot &&
1048 t_oop->offset() != Type::OffsetTop) {
1049 return true;
1050 }
1051 }
1052 return false;
1053 }
1055 //------------------------------Identity---------------------------------------
1056 // Loads are identity if previous store is to same address
1057 Node *LoadNode::Identity( PhaseTransform *phase ) {
1058 // If the previous store-maker is the right kind of Store, and the store is
1059 // to the same address, then we are equal to the value stored.
1060 Node* mem = in(MemNode::Memory);
1061 Node* value = can_see_stored_value(mem, phase);
1062 if( value ) {
1063 // byte, short & char stores truncate naturally.
1064 // A load has to load the truncated value which requires
1065 // some sort of masking operation and that requires an
1066 // Ideal call instead of an Identity call.
1067 if (memory_size() < BytesPerInt) {
1068 // If the input to the store does not fit with the load's result type,
1069 // it must be truncated via an Ideal call.
1070 if (!phase->type(value)->higher_equal(phase->type(this)))
1071 return this;
1072 }
1073 // (This works even when value is a Con, but LoadNode::Value
1074 // usually runs first, producing the singleton type of the Con.)
1075 return value;
1076 }
1078 // Search for an existing data phi which was generated before for the same
1079 // instance's field to avoid infinite generation of phis in a loop.
1080 Node *region = mem->in(0);
1081 if (is_instance_field_load_with_local_phi(region)) {
1082 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1083 int this_index = phase->C->get_alias_index(addr_t);
1084 int this_offset = addr_t->offset();
1085 int this_id = addr_t->is_oopptr()->instance_id();
1086 const Type* this_type = bottom_type();
1087 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1088 Node* phi = region->fast_out(i);
1089 if (phi->is_Phi() && phi != mem &&
1090 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1091 return phi;
1092 }
1093 }
1094 }
1096 return this;
1097 }
1100 // Returns true if the AliasType refers to the field that holds the
1101 // cached box array. Currently only handles the IntegerCache case.
1102 static bool is_autobox_cache(Compile::AliasType* atp) {
1103 if (atp != NULL && atp->field() != NULL) {
1104 ciField* field = atp->field();
1105 ciSymbol* klass = field->holder()->name();
1106 if (field->name() == ciSymbol::cache_field_name() &&
1107 field->holder()->uses_default_loader() &&
1108 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1109 return true;
1110 }
1111 }
1112 return false;
1113 }
1115 // Fetch the base value in the autobox array
1116 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1117 if (atp != NULL && atp->field() != NULL) {
1118 ciField* field = atp->field();
1119 ciSymbol* klass = field->holder()->name();
1120 if (field->name() == ciSymbol::cache_field_name() &&
1121 field->holder()->uses_default_loader() &&
1122 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1123 assert(field->is_constant(), "what?");
1124 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1125 // Fetch the box object at the base of the array and get its value
1126 ciInstance* box = array->obj_at(0)->as_instance();
1127 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1128 if (ik->nof_nonstatic_fields() == 1) {
1129 // This should be true nonstatic_field_at requires calling
1130 // nof_nonstatic_fields so check it anyway
1131 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1132 cache_offset = c.as_int();
1133 }
1134 return true;
1135 }
1136 }
1137 return false;
1138 }
1140 // Returns true if the AliasType refers to the value field of an
1141 // autobox object. Currently only handles Integer.
1142 static bool is_autobox_object(Compile::AliasType* atp) {
1143 if (atp != NULL && atp->field() != NULL) {
1144 ciField* field = atp->field();
1145 ciSymbol* klass = field->holder()->name();
1146 if (field->name() == ciSymbol::value_name() &&
1147 field->holder()->uses_default_loader() &&
1148 klass == ciSymbol::java_lang_Integer()) {
1149 return true;
1150 }
1151 }
1152 return false;
1153 }
1156 // We're loading from an object which has autobox behaviour.
1157 // If this object is result of a valueOf call we'll have a phi
1158 // merging a newly allocated object and a load from the cache.
1159 // We want to replace this load with the original incoming
1160 // argument to the valueOf call.
1161 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1162 Node* base = in(Address)->in(AddPNode::Base);
1163 if (base->is_Phi() && base->req() == 3) {
1164 AllocateNode* allocation = NULL;
1165 int allocation_index = -1;
1166 int load_index = -1;
1167 for (uint i = 1; i < base->req(); i++) {
1168 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1169 if (allocation != NULL) {
1170 allocation_index = i;
1171 load_index = 3 - allocation_index;
1172 break;
1173 }
1174 }
1175 bool has_load = ( allocation != NULL &&
1176 (base->in(load_index)->is_Load() ||
1177 base->in(load_index)->is_DecodeN() &&
1178 base->in(load_index)->in(1)->is_Load()) );
1179 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1180 // Push the loads from the phi that comes from valueOf up
1181 // through it to allow elimination of the loads and the recovery
1182 // of the original value.
1183 Node* mem_phi = in(Memory);
1184 Node* offset = in(Address)->in(AddPNode::Offset);
1185 Node* region = base->in(0);
1187 Node* in1 = clone();
1188 Node* in1_addr = in1->in(Address)->clone();
1189 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1190 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1191 in1_addr->set_req(AddPNode::Offset, offset);
1192 in1->set_req(0, region->in(allocation_index));
1193 in1->set_req(Address, in1_addr);
1194 in1->set_req(Memory, mem_phi->in(allocation_index));
1196 Node* in2 = clone();
1197 Node* in2_addr = in2->in(Address)->clone();
1198 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1199 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1200 in2_addr->set_req(AddPNode::Offset, offset);
1201 in2->set_req(0, region->in(load_index));
1202 in2->set_req(Address, in2_addr);
1203 in2->set_req(Memory, mem_phi->in(load_index));
1205 in1_addr = phase->transform(in1_addr);
1206 in1 = phase->transform(in1);
1207 in2_addr = phase->transform(in2_addr);
1208 in2 = phase->transform(in2);
1210 PhiNode* result = PhiNode::make_blank(region, this);
1211 result->set_req(allocation_index, in1);
1212 result->set_req(load_index, in2);
1213 return result;
1214 }
1215 } else if (base->is_Load() ||
1216 base->is_DecodeN() && base->in(1)->is_Load()) {
1217 if (base->is_DecodeN()) {
1218 // Get LoadN node which loads cached Integer object
1219 base = base->in(1);
1220 }
1221 // Eliminate the load of Integer.value for integers from the cache
1222 // array by deriving the value from the index into the array.
1223 // Capture the offset of the load and then reverse the computation.
1224 Node* load_base = base->in(Address)->in(AddPNode::Base);
1225 if (load_base->is_DecodeN()) {
1226 // Get LoadN node which loads IntegerCache.cache field
1227 load_base = load_base->in(1);
1228 }
1229 if (load_base != NULL) {
1230 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1231 intptr_t cache_offset;
1232 int shift = -1;
1233 Node* cache = NULL;
1234 if (is_autobox_cache(atp)) {
1235 shift = exact_log2(type2aelembytes(T_OBJECT));
1236 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1237 }
1238 if (cache != NULL && base->in(Address)->is_AddP()) {
1239 Node* elements[4];
1240 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1241 int cache_low;
1242 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1243 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1244 // Add up all the offsets making of the address of the load
1245 Node* result = elements[0];
1246 for (int i = 1; i < count; i++) {
1247 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1248 }
1249 // Remove the constant offset from the address and then
1250 // remove the scaling of the offset to recover the original index.
1251 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1252 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1253 // Peel the shift off directly but wrap it in a dummy node
1254 // since Ideal can't return existing nodes
1255 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1256 } else {
1257 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1258 }
1259 #ifdef _LP64
1260 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1261 #endif
1262 return result;
1263 }
1264 }
1265 }
1266 }
1267 return NULL;
1268 }
1270 //------------------------------split_through_phi------------------------------
1271 // Split instance field load through Phi.
1272 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1273 Node* mem = in(MemNode::Memory);
1274 Node* address = in(MemNode::Address);
1275 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1276 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1278 assert(mem->is_Phi() && (t_oop != NULL) &&
1279 t_oop->is_known_instance_field(), "invalide conditions");
1281 Node *region = mem->in(0);
1282 if (region == NULL) {
1283 return NULL; // Wait stable graph
1284 }
1285 uint cnt = mem->req();
1286 for (uint i = 1; i < cnt; i++) {
1287 Node* rc = region->in(i);
1288 if (rc == NULL || phase->type(rc) == Type::TOP)
1289 return NULL; // Wait stable graph
1290 Node *in = mem->in(i);
1291 if (in == NULL) {
1292 return NULL; // Wait stable graph
1293 }
1294 }
1295 // Check for loop invariant.
1296 if (cnt == 3) {
1297 for (uint i = 1; i < cnt; i++) {
1298 Node *in = mem->in(i);
1299 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1300 if (m == mem) {
1301 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1302 return this;
1303 }
1304 }
1305 }
1306 // Split through Phi (see original code in loopopts.cpp).
1307 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1309 // Do nothing here if Identity will find a value
1310 // (to avoid infinite chain of value phis generation).
1311 if (!phase->eqv(this, this->Identity(phase)))
1312 return NULL;
1314 // Skip the split if the region dominates some control edge of the address.
1315 if (!MemNode::all_controls_dominate(address, region))
1316 return NULL;
1318 const Type* this_type = this->bottom_type();
1319 int this_index = phase->C->get_alias_index(addr_t);
1320 int this_offset = addr_t->offset();
1321 int this_iid = addr_t->is_oopptr()->instance_id();
1322 PhaseIterGVN *igvn = phase->is_IterGVN();
1323 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1324 for (uint i = 1; i < region->req(); i++) {
1325 Node *x;
1326 Node* the_clone = NULL;
1327 if (region->in(i) == phase->C->top()) {
1328 x = phase->C->top(); // Dead path? Use a dead data op
1329 } else {
1330 x = this->clone(); // Else clone up the data op
1331 the_clone = x; // Remember for possible deletion.
1332 // Alter data node to use pre-phi inputs
1333 if (this->in(0) == region) {
1334 x->set_req(0, region->in(i));
1335 } else {
1336 x->set_req(0, NULL);
1337 }
1338 for (uint j = 1; j < this->req(); j++) {
1339 Node *in = this->in(j);
1340 if (in->is_Phi() && in->in(0) == region)
1341 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
1342 }
1343 }
1344 // Check for a 'win' on some paths
1345 const Type *t = x->Value(igvn);
1347 bool singleton = t->singleton();
1349 // See comments in PhaseIdealLoop::split_thru_phi().
1350 if (singleton && t == Type::TOP) {
1351 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1352 }
1354 if (singleton) {
1355 x = igvn->makecon(t);
1356 } else {
1357 // We now call Identity to try to simplify the cloned node.
1358 // Note that some Identity methods call phase->type(this).
1359 // Make sure that the type array is big enough for
1360 // our new node, even though we may throw the node away.
1361 // (This tweaking with igvn only works because x is a new node.)
1362 igvn->set_type(x, t);
1363 // If x is a TypeNode, capture any more-precise type permanently into Node
1364 // otherwise it will be not updated during igvn->transform since
1365 // igvn->type(x) is set to x->Value() already.
1366 x->raise_bottom_type(t);
1367 Node *y = x->Identity(igvn);
1368 if (y != x) {
1369 x = y;
1370 } else {
1371 y = igvn->hash_find(x);
1372 if (y) {
1373 x = y;
1374 } else {
1375 // Else x is a new node we are keeping
1376 // We do not need register_new_node_with_optimizer
1377 // because set_type has already been called.
1378 igvn->_worklist.push(x);
1379 }
1380 }
1381 }
1382 if (x != the_clone && the_clone != NULL)
1383 igvn->remove_dead_node(the_clone);
1384 phi->set_req(i, x);
1385 }
1386 // Record Phi
1387 igvn->register_new_node_with_optimizer(phi);
1388 return phi;
1389 }
1391 //------------------------------Ideal------------------------------------------
1392 // If the load is from Field memory and the pointer is non-null, we can
1393 // zero out the control input.
1394 // If the offset is constant and the base is an object allocation,
1395 // try to hook me up to the exact initializing store.
1396 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1397 Node* p = MemNode::Ideal_common(phase, can_reshape);
1398 if (p) return (p == NodeSentinel) ? NULL : p;
1400 Node* ctrl = in(MemNode::Control);
1401 Node* address = in(MemNode::Address);
1403 // Skip up past a SafePoint control. Cannot do this for Stores because
1404 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1405 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1406 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1407 ctrl = ctrl->in(0);
1408 set_req(MemNode::Control,ctrl);
1409 }
1411 intptr_t ignore = 0;
1412 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1413 if (base != NULL
1414 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1415 // Check for useless control edge in some common special cases
1416 if (in(MemNode::Control) != NULL
1417 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1418 && all_controls_dominate(base, phase->C->start())) {
1419 // A method-invariant, non-null address (constant or 'this' argument).
1420 set_req(MemNode::Control, NULL);
1421 }
1423 if (EliminateAutoBox && can_reshape) {
1424 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1425 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1426 if (is_autobox_object(atp)) {
1427 Node* result = eliminate_autobox(phase);
1428 if (result != NULL) return result;
1429 }
1430 }
1431 }
1433 Node* mem = in(MemNode::Memory);
1434 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1436 if (addr_t != NULL) {
1437 // try to optimize our memory input
1438 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1439 if (opt_mem != mem) {
1440 set_req(MemNode::Memory, opt_mem);
1441 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1442 return this;
1443 }
1444 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1445 if (can_reshape && opt_mem->is_Phi() &&
1446 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1447 PhaseIterGVN *igvn = phase->is_IterGVN();
1448 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1449 // Delay this transformation until memory Phi is processed.
1450 phase->is_IterGVN()->_worklist.push(this);
1451 return NULL;
1452 }
1453 // Split instance field load through Phi.
1454 Node* result = split_through_phi(phase);
1455 if (result != NULL) return result;
1456 }
1457 }
1459 // Check for prior store with a different base or offset; make Load
1460 // independent. Skip through any number of them. Bail out if the stores
1461 // are in an endless dead cycle and report no progress. This is a key
1462 // transform for Reflection. However, if after skipping through the Stores
1463 // we can't then fold up against a prior store do NOT do the transform as
1464 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1465 // array memory alive twice: once for the hoisted Load and again after the
1466 // bypassed Store. This situation only works if EVERYBODY who does
1467 // anti-dependence work knows how to bypass. I.e. we need all
1468 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1469 // the alias index stuff. So instead, peek through Stores and IFF we can
1470 // fold up, do so.
1471 Node* prev_mem = find_previous_store(phase);
1472 // Steps (a), (b): Walk past independent stores to find an exact match.
1473 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1474 // (c) See if we can fold up on the spot, but don't fold up here.
1475 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1476 // just return a prior value, which is done by Identity calls.
1477 if (can_see_stored_value(prev_mem, phase)) {
1478 // Make ready for step (d):
1479 set_req(MemNode::Memory, prev_mem);
1480 return this;
1481 }
1482 }
1484 return NULL; // No further progress
1485 }
1487 // Helper to recognize certain Klass fields which are invariant across
1488 // some group of array types (e.g., int[] or all T[] where T < Object).
1489 const Type*
1490 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1491 ciKlass* klass) const {
1492 if (tkls->offset() == in_bytes(Klass::modifier_flags_offset())) {
1493 // The field is Klass::_modifier_flags. Return its (constant) value.
1494 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1495 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1496 return TypeInt::make(klass->modifier_flags());
1497 }
1498 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
1499 // The field is Klass::_access_flags. Return its (constant) value.
1500 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1501 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1502 return TypeInt::make(klass->access_flags());
1503 }
1504 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
1505 // The field is Klass::_layout_helper. Return its constant value if known.
1506 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1507 return TypeInt::make(klass->layout_helper());
1508 }
1510 // No match.
1511 return NULL;
1512 }
1514 //------------------------------Value-----------------------------------------
1515 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1516 // Either input is TOP ==> the result is TOP
1517 Node* mem = in(MemNode::Memory);
1518 const Type *t1 = phase->type(mem);
1519 if (t1 == Type::TOP) return Type::TOP;
1520 Node* adr = in(MemNode::Address);
1521 const TypePtr* tp = phase->type(adr)->isa_ptr();
1522 if (tp == NULL || tp->empty()) return Type::TOP;
1523 int off = tp->offset();
1524 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1525 Compile* C = phase->C;
1527 // Try to guess loaded type from pointer type
1528 if (tp->base() == Type::AryPtr) {
1529 const Type *t = tp->is_aryptr()->elem();
1530 // Don't do this for integer types. There is only potential profit if
1531 // the element type t is lower than _type; that is, for int types, if _type is
1532 // more restrictive than t. This only happens here if one is short and the other
1533 // char (both 16 bits), and in those cases we've made an intentional decision
1534 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1535 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1536 //
1537 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1538 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1539 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1540 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1541 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1542 // In fact, that could have been the original type of p1, and p1 could have
1543 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1544 // expression (LShiftL quux 3) independently optimized to the constant 8.
1545 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1546 && (_type->isa_vect() == NULL)
1547 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1548 // t might actually be lower than _type, if _type is a unique
1549 // concrete subclass of abstract class t.
1550 // Make sure the reference is not into the header, by comparing
1551 // the offset against the offset of the start of the array's data.
1552 // Different array types begin at slightly different offsets (12 vs. 16).
1553 // We choose T_BYTE as an example base type that is least restrictive
1554 // as to alignment, which will therefore produce the smallest
1555 // possible base offset.
1556 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1557 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1558 const Type* jt = t->join(_type);
1559 // In any case, do not allow the join, per se, to empty out the type.
1560 if (jt->empty() && !t->empty()) {
1561 // This can happen if a interface-typed array narrows to a class type.
1562 jt = _type;
1563 }
1565 if (EliminateAutoBox && adr->is_AddP()) {
1566 // The pointers in the autobox arrays are always non-null
1567 Node* base = adr->in(AddPNode::Base);
1568 if (base != NULL &&
1569 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1570 Compile::AliasType* atp = C->alias_type(base->adr_type());
1571 if (is_autobox_cache(atp)) {
1572 return jt->join(TypePtr::NOTNULL)->is_ptr();
1573 }
1574 }
1575 }
1576 return jt;
1577 }
1578 }
1579 } else if (tp->base() == Type::InstPtr) {
1580 ciEnv* env = C->env();
1581 const TypeInstPtr* tinst = tp->is_instptr();
1582 ciKlass* klass = tinst->klass();
1583 assert( off != Type::OffsetBot ||
1584 // arrays can be cast to Objects
1585 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1586 // unsafe field access may not have a constant offset
1587 C->has_unsafe_access(),
1588 "Field accesses must be precise" );
1589 // For oop loads, we expect the _type to be precise
1590 if (klass == env->String_klass() &&
1591 adr->is_AddP() && off != Type::OffsetBot) {
1592 // For constant Strings treat the final fields as compile time constants.
1593 Node* base = adr->in(AddPNode::Base);
1594 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1595 if (t != NULL && t->singleton()) {
1596 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1597 if (field != NULL && field->is_final()) {
1598 ciObject* string = t->const_oop();
1599 ciConstant constant = string->as_instance()->field_value(field);
1600 if (constant.basic_type() == T_INT) {
1601 return TypeInt::make(constant.as_int());
1602 } else if (constant.basic_type() == T_ARRAY) {
1603 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1604 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1605 } else {
1606 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1607 }
1608 }
1609 }
1610 }
1611 }
1612 // Optimizations for constant objects
1613 ciObject* const_oop = tinst->const_oop();
1614 if (const_oop != NULL) {
1615 // For constant CallSites treat the target field as a compile time constant.
1616 if (const_oop->is_call_site()) {
1617 ciCallSite* call_site = const_oop->as_call_site();
1618 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1619 if (field != NULL && field->is_call_site_target()) {
1620 ciMethodHandle* target = call_site->get_target();
1621 if (target != NULL) { // just in case
1622 ciConstant constant(T_OBJECT, target);
1623 const Type* t;
1624 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1625 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1626 } else {
1627 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1628 }
1629 // Add a dependence for invalidation of the optimization.
1630 if (!call_site->is_constant_call_site()) {
1631 C->dependencies()->assert_call_site_target_value(call_site, target);
1632 }
1633 return t;
1634 }
1635 }
1636 }
1637 }
1638 } else if (tp->base() == Type::KlassPtr) {
1639 assert( off != Type::OffsetBot ||
1640 // arrays can be cast to Objects
1641 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1642 // also allow array-loading from the primary supertype
1643 // array during subtype checks
1644 Opcode() == Op_LoadKlass,
1645 "Field accesses must be precise" );
1646 // For klass/static loads, we expect the _type to be precise
1647 }
1649 const TypeKlassPtr *tkls = tp->isa_klassptr();
1650 if (tkls != NULL && !StressReflectiveCode) {
1651 ciKlass* klass = tkls->klass();
1652 if (klass->is_loaded() && tkls->klass_is_exact()) {
1653 // We are loading a field from a Klass metaobject whose identity
1654 // is known at compile time (the type is "exact" or "precise").
1655 // Check for fields we know are maintained as constants by the VM.
1656 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
1657 // The field is Klass::_super_check_offset. Return its (constant) value.
1658 // (Folds up type checking code.)
1659 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1660 return TypeInt::make(klass->super_check_offset());
1661 }
1662 // Compute index into primary_supers array
1663 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1664 // Check for overflowing; use unsigned compare to handle the negative case.
1665 if( depth < ciKlass::primary_super_limit() ) {
1666 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1667 // (Folds up type checking code.)
1668 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1669 ciKlass *ss = klass->super_of_depth(depth);
1670 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1671 }
1672 const Type* aift = load_array_final_field(tkls, klass);
1673 if (aift != NULL) return aift;
1674 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset())
1675 && klass->is_array_klass()) {
1676 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1677 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1678 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1679 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1680 }
1681 if (tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
1682 // The field is Klass::_java_mirror. Return its (constant) value.
1683 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1684 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1685 return TypeInstPtr::make(klass->java_mirror());
1686 }
1687 }
1689 // We can still check if we are loading from the primary_supers array at a
1690 // shallow enough depth. Even though the klass is not exact, entries less
1691 // than or equal to its super depth are correct.
1692 if (klass->is_loaded() ) {
1693 ciType *inner = klass;
1694 while( inner->is_obj_array_klass() )
1695 inner = inner->as_obj_array_klass()->base_element_type();
1696 if( inner->is_instance_klass() &&
1697 !inner->as_instance_klass()->flags().is_interface() ) {
1698 // Compute index into primary_supers array
1699 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
1700 // Check for overflowing; use unsigned compare to handle the negative case.
1701 if( depth < ciKlass::primary_super_limit() &&
1702 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1703 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1704 // (Folds up type checking code.)
1705 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1706 ciKlass *ss = klass->super_of_depth(depth);
1707 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1708 }
1709 }
1710 }
1712 // If the type is enough to determine that the thing is not an array,
1713 // we can give the layout_helper a positive interval type.
1714 // This will help short-circuit some reflective code.
1715 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())
1716 && !klass->is_array_klass() // not directly typed as an array
1717 && !klass->is_interface() // specifically not Serializable & Cloneable
1718 && !klass->is_java_lang_Object() // not the supertype of all T[]
1719 ) {
1720 // Note: When interfaces are reliable, we can narrow the interface
1721 // test to (klass != Serializable && klass != Cloneable).
1722 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1723 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1724 // The key property of this type is that it folds up tests
1725 // for array-ness, since it proves that the layout_helper is positive.
1726 // Thus, a generic value like the basic object layout helper works fine.
1727 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1728 }
1729 }
1731 // If we are loading from a freshly-allocated object, produce a zero,
1732 // if the load is provably beyond the header of the object.
1733 // (Also allow a variable load from a fresh array to produce zero.)
1734 const TypeOopPtr *tinst = tp->isa_oopptr();
1735 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1736 if (ReduceFieldZeroing || is_instance) {
1737 Node* value = can_see_stored_value(mem,phase);
1738 if (value != NULL && value->is_Con()) {
1739 assert(value->bottom_type()->higher_equal(_type),"sanity");
1740 return value->bottom_type();
1741 }
1742 }
1744 if (is_instance) {
1745 // If we have an instance type and our memory input is the
1746 // programs's initial memory state, there is no matching store,
1747 // so just return a zero of the appropriate type
1748 Node *mem = in(MemNode::Memory);
1749 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1750 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1751 return Type::get_zero_type(_type->basic_type());
1752 }
1753 }
1754 return _type;
1755 }
1757 //------------------------------match_edge-------------------------------------
1758 // Do we Match on this edge index or not? Match only the address.
1759 uint LoadNode::match_edge(uint idx) const {
1760 return idx == MemNode::Address;
1761 }
1763 //--------------------------LoadBNode::Ideal--------------------------------------
1764 //
1765 // If the previous store is to the same address as this load,
1766 // and the value stored was larger than a byte, replace this load
1767 // with the value stored truncated to a byte. If no truncation is
1768 // needed, the replacement is done in LoadNode::Identity().
1769 //
1770 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1771 Node* mem = in(MemNode::Memory);
1772 Node* value = can_see_stored_value(mem,phase);
1773 if( value && !phase->type(value)->higher_equal( _type ) ) {
1774 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1775 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1776 }
1777 // Identity call will handle the case where truncation is not needed.
1778 return LoadNode::Ideal(phase, can_reshape);
1779 }
1781 const Type* LoadBNode::Value(PhaseTransform *phase) const {
1782 Node* mem = in(MemNode::Memory);
1783 Node* value = can_see_stored_value(mem,phase);
1784 if (value != NULL && value->is_Con() &&
1785 !value->bottom_type()->higher_equal(_type)) {
1786 // If the input to the store does not fit with the load's result type,
1787 // it must be truncated. We can't delay until Ideal call since
1788 // a singleton Value is needed for split_thru_phi optimization.
1789 int con = value->get_int();
1790 return TypeInt::make((con << 24) >> 24);
1791 }
1792 return LoadNode::Value(phase);
1793 }
1795 //--------------------------LoadUBNode::Ideal-------------------------------------
1796 //
1797 // If the previous store is to the same address as this load,
1798 // and the value stored was larger than a byte, replace this load
1799 // with the value stored truncated to a byte. If no truncation is
1800 // needed, the replacement is done in LoadNode::Identity().
1801 //
1802 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1803 Node* mem = in(MemNode::Memory);
1804 Node* value = can_see_stored_value(mem, phase);
1805 if (value && !phase->type(value)->higher_equal(_type))
1806 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1807 // Identity call will handle the case where truncation is not needed.
1808 return LoadNode::Ideal(phase, can_reshape);
1809 }
1811 const Type* LoadUBNode::Value(PhaseTransform *phase) const {
1812 Node* mem = in(MemNode::Memory);
1813 Node* value = can_see_stored_value(mem,phase);
1814 if (value != NULL && value->is_Con() &&
1815 !value->bottom_type()->higher_equal(_type)) {
1816 // If the input to the store does not fit with the load's result type,
1817 // it must be truncated. We can't delay until Ideal call since
1818 // a singleton Value is needed for split_thru_phi optimization.
1819 int con = value->get_int();
1820 return TypeInt::make(con & 0xFF);
1821 }
1822 return LoadNode::Value(phase);
1823 }
1825 //--------------------------LoadUSNode::Ideal-------------------------------------
1826 //
1827 // If the previous store is to the same address as this load,
1828 // and the value stored was larger than a char, replace this load
1829 // with the value stored truncated to a char. If no truncation is
1830 // needed, the replacement is done in LoadNode::Identity().
1831 //
1832 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1833 Node* mem = in(MemNode::Memory);
1834 Node* value = can_see_stored_value(mem,phase);
1835 if( value && !phase->type(value)->higher_equal( _type ) )
1836 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1837 // Identity call will handle the case where truncation is not needed.
1838 return LoadNode::Ideal(phase, can_reshape);
1839 }
1841 const Type* LoadUSNode::Value(PhaseTransform *phase) const {
1842 Node* mem = in(MemNode::Memory);
1843 Node* value = can_see_stored_value(mem,phase);
1844 if (value != NULL && value->is_Con() &&
1845 !value->bottom_type()->higher_equal(_type)) {
1846 // If the input to the store does not fit with the load's result type,
1847 // it must be truncated. We can't delay until Ideal call since
1848 // a singleton Value is needed for split_thru_phi optimization.
1849 int con = value->get_int();
1850 return TypeInt::make(con & 0xFFFF);
1851 }
1852 return LoadNode::Value(phase);
1853 }
1855 //--------------------------LoadSNode::Ideal--------------------------------------
1856 //
1857 // If the previous store is to the same address as this load,
1858 // and the value stored was larger than a short, replace this load
1859 // with the value stored truncated to a short. If no truncation is
1860 // needed, the replacement is done in LoadNode::Identity().
1861 //
1862 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1863 Node* mem = in(MemNode::Memory);
1864 Node* value = can_see_stored_value(mem,phase);
1865 if( value && !phase->type(value)->higher_equal( _type ) ) {
1866 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1867 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1868 }
1869 // Identity call will handle the case where truncation is not needed.
1870 return LoadNode::Ideal(phase, can_reshape);
1871 }
1873 const Type* LoadSNode::Value(PhaseTransform *phase) const {
1874 Node* mem = in(MemNode::Memory);
1875 Node* value = can_see_stored_value(mem,phase);
1876 if (value != NULL && value->is_Con() &&
1877 !value->bottom_type()->higher_equal(_type)) {
1878 // If the input to the store does not fit with the load's result type,
1879 // it must be truncated. We can't delay until Ideal call since
1880 // a singleton Value is needed for split_thru_phi optimization.
1881 int con = value->get_int();
1882 return TypeInt::make((con << 16) >> 16);
1883 }
1884 return LoadNode::Value(phase);
1885 }
1887 //=============================================================================
1888 //----------------------------LoadKlassNode::make------------------------------
1889 // Polymorphic factory method:
1890 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1891 Compile* C = gvn.C;
1892 Node *ctl = NULL;
1893 // sanity check the alias category against the created node type
1894 const TypePtr *adr_type = adr->bottom_type()->isa_ptr();
1895 assert(adr_type != NULL, "expecting TypeKlassPtr");
1896 #ifdef _LP64
1897 if (adr_type->is_ptr_to_narrowoop()) {
1898 assert(UseCompressedKlassPointers, "no compressed klasses");
1899 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1900 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1901 }
1902 #endif
1903 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1904 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1905 }
1907 //------------------------------Value------------------------------------------
1908 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1909 return klass_value_common(phase);
1910 }
1912 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1913 // Either input is TOP ==> the result is TOP
1914 const Type *t1 = phase->type( in(MemNode::Memory) );
1915 if (t1 == Type::TOP) return Type::TOP;
1916 Node *adr = in(MemNode::Address);
1917 const Type *t2 = phase->type( adr );
1918 if (t2 == Type::TOP) return Type::TOP;
1919 const TypePtr *tp = t2->is_ptr();
1920 if (TypePtr::above_centerline(tp->ptr()) ||
1921 tp->ptr() == TypePtr::Null) return Type::TOP;
1923 // Return a more precise klass, if possible
1924 const TypeInstPtr *tinst = tp->isa_instptr();
1925 if (tinst != NULL) {
1926 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1927 int offset = tinst->offset();
1928 if (ik == phase->C->env()->Class_klass()
1929 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1930 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1931 // We are loading a special hidden field from a Class mirror object,
1932 // the field which points to the VM's Klass metaobject.
1933 ciType* t = tinst->java_mirror_type();
1934 // java_mirror_type returns non-null for compile-time Class constants.
1935 if (t != NULL) {
1936 // constant oop => constant klass
1937 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1938 return TypeKlassPtr::make(ciArrayKlass::make(t));
1939 }
1940 if (!t->is_klass()) {
1941 // a primitive Class (e.g., int.class) has NULL for a klass field
1942 return TypePtr::NULL_PTR;
1943 }
1944 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1945 return TypeKlassPtr::make(t->as_klass());
1946 }
1947 // non-constant mirror, so we can't tell what's going on
1948 }
1949 if( !ik->is_loaded() )
1950 return _type; // Bail out if not loaded
1951 if (offset == oopDesc::klass_offset_in_bytes()) {
1952 if (tinst->klass_is_exact()) {
1953 return TypeKlassPtr::make(ik);
1954 }
1955 // See if we can become precise: no subklasses and no interface
1956 // (Note: We need to support verified interfaces.)
1957 if (!ik->is_interface() && !ik->has_subklass()) {
1958 //assert(!UseExactTypes, "this code should be useless with exact types");
1959 // Add a dependence; if any subclass added we need to recompile
1960 if (!ik->is_final()) {
1961 // %%% should use stronger assert_unique_concrete_subtype instead
1962 phase->C->dependencies()->assert_leaf_type(ik);
1963 }
1964 // Return precise klass
1965 return TypeKlassPtr::make(ik);
1966 }
1968 // Return root of possible klass
1969 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1970 }
1971 }
1973 // Check for loading klass from an array
1974 const TypeAryPtr *tary = tp->isa_aryptr();
1975 if( tary != NULL ) {
1976 ciKlass *tary_klass = tary->klass();
1977 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1978 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1979 if (tary->klass_is_exact()) {
1980 return TypeKlassPtr::make(tary_klass);
1981 }
1982 ciArrayKlass *ak = tary->klass()->as_array_klass();
1983 // If the klass is an object array, we defer the question to the
1984 // array component klass.
1985 if( ak->is_obj_array_klass() ) {
1986 assert( ak->is_loaded(), "" );
1987 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1988 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1989 ciInstanceKlass* ik = base_k->as_instance_klass();
1990 // See if we can become precise: no subklasses and no interface
1991 if (!ik->is_interface() && !ik->has_subklass()) {
1992 //assert(!UseExactTypes, "this code should be useless with exact types");
1993 // Add a dependence; if any subclass added we need to recompile
1994 if (!ik->is_final()) {
1995 phase->C->dependencies()->assert_leaf_type(ik);
1996 }
1997 // Return precise array klass
1998 return TypeKlassPtr::make(ak);
1999 }
2000 }
2001 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
2002 } else { // Found a type-array?
2003 //assert(!UseExactTypes, "this code should be useless with exact types");
2004 assert( ak->is_type_array_klass(), "" );
2005 return TypeKlassPtr::make(ak); // These are always precise
2006 }
2007 }
2008 }
2010 // Check for loading klass from an array klass
2011 const TypeKlassPtr *tkls = tp->isa_klassptr();
2012 if (tkls != NULL && !StressReflectiveCode) {
2013 ciKlass* klass = tkls->klass();
2014 if( !klass->is_loaded() )
2015 return _type; // Bail out if not loaded
2016 if( klass->is_obj_array_klass() &&
2017 tkls->offset() == in_bytes(objArrayKlass::element_klass_offset())) {
2018 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
2019 // // Always returning precise element type is incorrect,
2020 // // e.g., element type could be object and array may contain strings
2021 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2023 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2024 // according to the element type's subclassing.
2025 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
2026 }
2027 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
2028 tkls->offset() == in_bytes(Klass::super_offset())) {
2029 ciKlass* sup = klass->as_instance_klass()->super();
2030 // The field is Klass::_super. Return its (constant) value.
2031 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2032 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
2033 }
2034 }
2036 // Bailout case
2037 return LoadNode::Value(phase);
2038 }
2040 //------------------------------Identity---------------------------------------
2041 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2042 // Also feed through the klass in Allocate(...klass...)._klass.
2043 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
2044 return klass_identity_common(phase);
2045 }
2047 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
2048 Node* x = LoadNode::Identity(phase);
2049 if (x != this) return x;
2051 // Take apart the address into an oop and and offset.
2052 // Return 'this' if we cannot.
2053 Node* adr = in(MemNode::Address);
2054 intptr_t offset = 0;
2055 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2056 if (base == NULL) return this;
2057 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2058 if (toop == NULL) return this;
2060 // We can fetch the klass directly through an AllocateNode.
2061 // This works even if the klass is not constant (clone or newArray).
2062 if (offset == oopDesc::klass_offset_in_bytes()) {
2063 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2064 if (allocated_klass != NULL) {
2065 return allocated_klass;
2066 }
2067 }
2069 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2070 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
2071 // See inline_native_Class_query for occurrences of these patterns.
2072 // Java Example: x.getClass().isAssignableFrom(y)
2073 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
2074 //
2075 // This improves reflective code, often making the Class
2076 // mirror go completely dead. (Current exception: Class
2077 // mirrors may appear in debug info, but we could clean them out by
2078 // introducing a new debug info operator for Klass*.java_mirror).
2079 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
2080 && (offset == java_lang_Class::klass_offset_in_bytes() ||
2081 offset == java_lang_Class::array_klass_offset_in_bytes())) {
2082 // We are loading a special hidden field from a Class mirror,
2083 // the field which points to its Klass or arrayKlass metaobject.
2084 if (base->is_Load()) {
2085 Node* adr2 = base->in(MemNode::Address);
2086 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2087 if (tkls != NULL && !tkls->empty()
2088 && (tkls->klass()->is_instance_klass() ||
2089 tkls->klass()->is_array_klass())
2090 && adr2->is_AddP()
2091 ) {
2092 int mirror_field = in_bytes(Klass::java_mirror_offset());
2093 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2094 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
2095 }
2096 if (tkls->offset() == mirror_field) {
2097 return adr2->in(AddPNode::Base);
2098 }
2099 }
2100 }
2101 }
2103 return this;
2104 }
2107 //------------------------------Value------------------------------------------
2108 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2109 const Type *t = klass_value_common(phase);
2110 if (t == Type::TOP)
2111 return t;
2113 return t->make_narrowoop();
2114 }
2116 //------------------------------Identity---------------------------------------
2117 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2118 // Also feed through the klass in Allocate(...klass...)._klass.
2119 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2120 Node *x = klass_identity_common(phase);
2122 const Type *t = phase->type( x );
2123 if( t == Type::TOP ) return x;
2124 if( t->isa_narrowoop()) return x;
2126 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
2127 }
2129 //------------------------------Value-----------------------------------------
2130 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2131 // Either input is TOP ==> the result is TOP
2132 const Type *t1 = phase->type( in(MemNode::Memory) );
2133 if( t1 == Type::TOP ) return Type::TOP;
2134 Node *adr = in(MemNode::Address);
2135 const Type *t2 = phase->type( adr );
2136 if( t2 == Type::TOP ) return Type::TOP;
2137 const TypePtr *tp = t2->is_ptr();
2138 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2139 const TypeAryPtr *tap = tp->isa_aryptr();
2140 if( !tap ) return _type;
2141 return tap->size();
2142 }
2144 //-------------------------------Ideal---------------------------------------
2145 // Feed through the length in AllocateArray(...length...)._length.
2146 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2147 Node* p = MemNode::Ideal_common(phase, can_reshape);
2148 if (p) return (p == NodeSentinel) ? NULL : p;
2150 // Take apart the address into an oop and and offset.
2151 // Return 'this' if we cannot.
2152 Node* adr = in(MemNode::Address);
2153 intptr_t offset = 0;
2154 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2155 if (base == NULL) return NULL;
2156 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2157 if (tary == NULL) return NULL;
2159 // We can fetch the length directly through an AllocateArrayNode.
2160 // This works even if the length is not constant (clone or newArray).
2161 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2162 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2163 if (alloc != NULL) {
2164 Node* allocated_length = alloc->Ideal_length();
2165 Node* len = alloc->make_ideal_length(tary, phase);
2166 if (allocated_length != len) {
2167 // New CastII improves on this.
2168 return len;
2169 }
2170 }
2171 }
2173 return NULL;
2174 }
2176 //------------------------------Identity---------------------------------------
2177 // Feed through the length in AllocateArray(...length...)._length.
2178 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2179 Node* x = LoadINode::Identity(phase);
2180 if (x != this) return x;
2182 // Take apart the address into an oop and and offset.
2183 // Return 'this' if we cannot.
2184 Node* adr = in(MemNode::Address);
2185 intptr_t offset = 0;
2186 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2187 if (base == NULL) return this;
2188 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2189 if (tary == NULL) return this;
2191 // We can fetch the length directly through an AllocateArrayNode.
2192 // This works even if the length is not constant (clone or newArray).
2193 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2194 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2195 if (alloc != NULL) {
2196 Node* allocated_length = alloc->Ideal_length();
2197 // Do not allow make_ideal_length to allocate a CastII node.
2198 Node* len = alloc->make_ideal_length(tary, phase, false);
2199 if (allocated_length == len) {
2200 // Return allocated_length only if it would not be improved by a CastII.
2201 return allocated_length;
2202 }
2203 }
2204 }
2206 return this;
2208 }
2210 //=============================================================================
2211 //---------------------------StoreNode::make-----------------------------------
2212 // Polymorphic factory method:
2213 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2214 Compile* C = gvn.C;
2215 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2216 ctl != NULL, "raw memory operations should have control edge");
2218 switch (bt) {
2219 case T_BOOLEAN:
2220 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2221 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2222 case T_CHAR:
2223 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2224 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2225 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2226 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2227 case T_METADATA:
2228 case T_ADDRESS:
2229 case T_OBJECT:
2230 #ifdef _LP64
2231 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2232 (UseCompressedKlassPointers && val->bottom_type()->isa_klassptr() &&
2233 adr->bottom_type()->isa_rawptr())) {
2234 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2235 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2236 } else
2237 #endif
2238 {
2239 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2240 }
2241 }
2242 ShouldNotReachHere();
2243 return (StoreNode*)NULL;
2244 }
2246 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2247 bool require_atomic = true;
2248 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2249 }
2252 //--------------------------bottom_type----------------------------------------
2253 const Type *StoreNode::bottom_type() const {
2254 return Type::MEMORY;
2255 }
2257 //------------------------------hash-------------------------------------------
2258 uint StoreNode::hash() const {
2259 // unroll addition of interesting fields
2260 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2262 // Since they are not commoned, do not hash them:
2263 return NO_HASH;
2264 }
2266 //------------------------------Ideal------------------------------------------
2267 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2268 // When a store immediately follows a relevant allocation/initialization,
2269 // try to capture it into the initialization, or hoist it above.
2270 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2271 Node* p = MemNode::Ideal_common(phase, can_reshape);
2272 if (p) return (p == NodeSentinel) ? NULL : p;
2274 Node* mem = in(MemNode::Memory);
2275 Node* address = in(MemNode::Address);
2277 // Back-to-back stores to same address? Fold em up. Generally
2278 // unsafe if I have intervening uses... Also disallowed for StoreCM
2279 // since they must follow each StoreP operation. Redundant StoreCMs
2280 // are eliminated just before matching in final_graph_reshape.
2281 if (mem->is_Store() && mem->in(MemNode::Address)->eqv_uncast(address) &&
2282 mem->Opcode() != Op_StoreCM) {
2283 // Looking at a dead closed cycle of memory?
2284 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2286 assert(Opcode() == mem->Opcode() ||
2287 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2288 "no mismatched stores, except on raw memory");
2290 if (mem->outcnt() == 1 && // check for intervening uses
2291 mem->as_Store()->memory_size() <= this->memory_size()) {
2292 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2293 // For example, 'mem' might be the final state at a conditional return.
2294 // Or, 'mem' might be used by some node which is live at the same time
2295 // 'this' is live, which might be unschedulable. So, require exactly
2296 // ONE user, the 'this' store, until such time as we clone 'mem' for
2297 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2298 if (can_reshape) { // (%%% is this an anachronism?)
2299 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2300 phase->is_IterGVN());
2301 } else {
2302 // It's OK to do this in the parser, since DU info is always accurate,
2303 // and the parser always refers to nodes via SafePointNode maps.
2304 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2305 }
2306 return this;
2307 }
2308 }
2310 // Capture an unaliased, unconditional, simple store into an initializer.
2311 // Or, if it is independent of the allocation, hoist it above the allocation.
2312 if (ReduceFieldZeroing && /*can_reshape &&*/
2313 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2314 InitializeNode* init = mem->in(0)->as_Initialize();
2315 intptr_t offset = init->can_capture_store(this, phase);
2316 if (offset > 0) {
2317 Node* moved = init->capture_store(this, offset, phase);
2318 // If the InitializeNode captured me, it made a raw copy of me,
2319 // and I need to disappear.
2320 if (moved != NULL) {
2321 // %%% hack to ensure that Ideal returns a new node:
2322 mem = MergeMemNode::make(phase->C, mem);
2323 return mem; // fold me away
2324 }
2325 }
2326 }
2328 return NULL; // No further progress
2329 }
2331 //------------------------------Value-----------------------------------------
2332 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2333 // Either input is TOP ==> the result is TOP
2334 const Type *t1 = phase->type( in(MemNode::Memory) );
2335 if( t1 == Type::TOP ) return Type::TOP;
2336 const Type *t2 = phase->type( in(MemNode::Address) );
2337 if( t2 == Type::TOP ) return Type::TOP;
2338 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2339 if( t3 == Type::TOP ) return Type::TOP;
2340 return Type::MEMORY;
2341 }
2343 //------------------------------Identity---------------------------------------
2344 // Remove redundant stores:
2345 // Store(m, p, Load(m, p)) changes to m.
2346 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2347 Node *StoreNode::Identity( PhaseTransform *phase ) {
2348 Node* mem = in(MemNode::Memory);
2349 Node* adr = in(MemNode::Address);
2350 Node* val = in(MemNode::ValueIn);
2352 // Load then Store? Then the Store is useless
2353 if (val->is_Load() &&
2354 val->in(MemNode::Address)->eqv_uncast(adr) &&
2355 val->in(MemNode::Memory )->eqv_uncast(mem) &&
2356 val->as_Load()->store_Opcode() == Opcode()) {
2357 return mem;
2358 }
2360 // Two stores in a row of the same value?
2361 if (mem->is_Store() &&
2362 mem->in(MemNode::Address)->eqv_uncast(adr) &&
2363 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
2364 mem->Opcode() == Opcode()) {
2365 return mem;
2366 }
2368 // Store of zero anywhere into a freshly-allocated object?
2369 // Then the store is useless.
2370 // (It must already have been captured by the InitializeNode.)
2371 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2372 // a newly allocated object is already all-zeroes everywhere
2373 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2374 return mem;
2375 }
2377 // the store may also apply to zero-bits in an earlier object
2378 Node* prev_mem = find_previous_store(phase);
2379 // Steps (a), (b): Walk past independent stores to find an exact match.
2380 if (prev_mem != NULL) {
2381 Node* prev_val = can_see_stored_value(prev_mem, phase);
2382 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2383 // prev_val and val might differ by a cast; it would be good
2384 // to keep the more informative of the two.
2385 return mem;
2386 }
2387 }
2388 }
2390 return this;
2391 }
2393 //------------------------------match_edge-------------------------------------
2394 // Do we Match on this edge index or not? Match only memory & value
2395 uint StoreNode::match_edge(uint idx) const {
2396 return idx == MemNode::Address || idx == MemNode::ValueIn;
2397 }
2399 //------------------------------cmp--------------------------------------------
2400 // Do not common stores up together. They generally have to be split
2401 // back up anyways, so do not bother.
2402 uint StoreNode::cmp( const Node &n ) const {
2403 return (&n == this); // Always fail except on self
2404 }
2406 //------------------------------Ideal_masked_input-----------------------------
2407 // Check for a useless mask before a partial-word store
2408 // (StoreB ... (AndI valIn conIa) )
2409 // If (conIa & mask == mask) this simplifies to
2410 // (StoreB ... (valIn) )
2411 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2412 Node *val = in(MemNode::ValueIn);
2413 if( val->Opcode() == Op_AndI ) {
2414 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2415 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2416 set_req(MemNode::ValueIn, val->in(1));
2417 return this;
2418 }
2419 }
2420 return NULL;
2421 }
2424 //------------------------------Ideal_sign_extended_input----------------------
2425 // Check for useless sign-extension before a partial-word store
2426 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2427 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2428 // (StoreB ... (valIn) )
2429 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2430 Node *val = in(MemNode::ValueIn);
2431 if( val->Opcode() == Op_RShiftI ) {
2432 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2433 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2434 Node *shl = val->in(1);
2435 if( shl->Opcode() == Op_LShiftI ) {
2436 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2437 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2438 set_req(MemNode::ValueIn, shl->in(1));
2439 return this;
2440 }
2441 }
2442 }
2443 }
2444 return NULL;
2445 }
2447 //------------------------------value_never_loaded-----------------------------------
2448 // Determine whether there are any possible loads of the value stored.
2449 // For simplicity, we actually check if there are any loads from the
2450 // address stored to, not just for loads of the value stored by this node.
2451 //
2452 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2453 Node *adr = in(Address);
2454 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2455 if (adr_oop == NULL)
2456 return false;
2457 if (!adr_oop->is_known_instance_field())
2458 return false; // if not a distinct instance, there may be aliases of the address
2459 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2460 Node *use = adr->fast_out(i);
2461 int opc = use->Opcode();
2462 if (use->is_Load() || use->is_LoadStore()) {
2463 return false;
2464 }
2465 }
2466 return true;
2467 }
2469 //=============================================================================
2470 //------------------------------Ideal------------------------------------------
2471 // If the store is from an AND mask that leaves the low bits untouched, then
2472 // we can skip the AND operation. If the store is from a sign-extension
2473 // (a left shift, then right shift) we can skip both.
2474 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2475 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2476 if( progress != NULL ) return progress;
2478 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2479 if( progress != NULL ) return progress;
2481 // Finally check the default case
2482 return StoreNode::Ideal(phase, can_reshape);
2483 }
2485 //=============================================================================
2486 //------------------------------Ideal------------------------------------------
2487 // If the store is from an AND mask that leaves the low bits untouched, then
2488 // we can skip the AND operation
2489 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2490 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2491 if( progress != NULL ) return progress;
2493 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2494 if( progress != NULL ) return progress;
2496 // Finally check the default case
2497 return StoreNode::Ideal(phase, can_reshape);
2498 }
2500 //=============================================================================
2501 //------------------------------Identity---------------------------------------
2502 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2503 // No need to card mark when storing a null ptr
2504 Node* my_store = in(MemNode::OopStore);
2505 if (my_store->is_Store()) {
2506 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2507 if( t1 == TypePtr::NULL_PTR ) {
2508 return in(MemNode::Memory);
2509 }
2510 }
2511 return this;
2512 }
2514 //=============================================================================
2515 //------------------------------Ideal---------------------------------------
2516 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2517 Node* progress = StoreNode::Ideal(phase, can_reshape);
2518 if (progress != NULL) return progress;
2520 Node* my_store = in(MemNode::OopStore);
2521 if (my_store->is_MergeMem()) {
2522 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2523 set_req(MemNode::OopStore, mem);
2524 return this;
2525 }
2527 return NULL;
2528 }
2530 //------------------------------Value-----------------------------------------
2531 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2532 // Either input is TOP ==> the result is TOP
2533 const Type *t = phase->type( in(MemNode::Memory) );
2534 if( t == Type::TOP ) return Type::TOP;
2535 t = phase->type( in(MemNode::Address) );
2536 if( t == Type::TOP ) return Type::TOP;
2537 t = phase->type( in(MemNode::ValueIn) );
2538 if( t == Type::TOP ) return Type::TOP;
2539 // If extra input is TOP ==> the result is TOP
2540 t = phase->type( in(MemNode::OopStore) );
2541 if( t == Type::TOP ) return Type::TOP;
2543 return StoreNode::Value( phase );
2544 }
2547 //=============================================================================
2548 //----------------------------------SCMemProjNode------------------------------
2549 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2550 {
2551 return bottom_type();
2552 }
2554 //=============================================================================
2555 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2556 init_req(MemNode::Control, c );
2557 init_req(MemNode::Memory , mem);
2558 init_req(MemNode::Address, adr);
2559 init_req(MemNode::ValueIn, val);
2560 init_req( ExpectedIn, ex );
2561 init_class_id(Class_LoadStore);
2563 }
2565 //=============================================================================
2566 //-------------------------------adr_type--------------------------------------
2567 // Do we Match on this edge index or not? Do not match memory
2568 const TypePtr* ClearArrayNode::adr_type() const {
2569 Node *adr = in(3);
2570 return MemNode::calculate_adr_type(adr->bottom_type());
2571 }
2573 //------------------------------match_edge-------------------------------------
2574 // Do we Match on this edge index or not? Do not match memory
2575 uint ClearArrayNode::match_edge(uint idx) const {
2576 return idx > 1;
2577 }
2579 //------------------------------Identity---------------------------------------
2580 // Clearing a zero length array does nothing
2581 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2582 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2583 }
2585 //------------------------------Idealize---------------------------------------
2586 // Clearing a short array is faster with stores
2587 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2588 const int unit = BytesPerLong;
2589 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2590 if (!t) return NULL;
2591 if (!t->is_con()) return NULL;
2592 intptr_t raw_count = t->get_con();
2593 intptr_t size = raw_count;
2594 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2595 // Clearing nothing uses the Identity call.
2596 // Negative clears are possible on dead ClearArrays
2597 // (see jck test stmt114.stmt11402.val).
2598 if (size <= 0 || size % unit != 0) return NULL;
2599 intptr_t count = size / unit;
2600 // Length too long; use fast hardware clear
2601 if (size > Matcher::init_array_short_size) return NULL;
2602 Node *mem = in(1);
2603 if( phase->type(mem)==Type::TOP ) return NULL;
2604 Node *adr = in(3);
2605 const Type* at = phase->type(adr);
2606 if( at==Type::TOP ) return NULL;
2607 const TypePtr* atp = at->isa_ptr();
2608 // adjust atp to be the correct array element address type
2609 if (atp == NULL) atp = TypePtr::BOTTOM;
2610 else atp = atp->add_offset(Type::OffsetBot);
2611 // Get base for derived pointer purposes
2612 if( adr->Opcode() != Op_AddP ) Unimplemented();
2613 Node *base = adr->in(1);
2615 Node *zero = phase->makecon(TypeLong::ZERO);
2616 Node *off = phase->MakeConX(BytesPerLong);
2617 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2618 count--;
2619 while( count-- ) {
2620 mem = phase->transform(mem);
2621 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2622 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2623 }
2624 return mem;
2625 }
2627 //----------------------------step_through----------------------------------
2628 // Return allocation input memory edge if it is different instance
2629 // or itself if it is the one we are looking for.
2630 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2631 Node* n = *np;
2632 assert(n->is_ClearArray(), "sanity");
2633 intptr_t offset;
2634 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2635 // This method is called only before Allocate nodes are expanded during
2636 // macro nodes expansion. Before that ClearArray nodes are only generated
2637 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2638 assert(alloc != NULL, "should have allocation");
2639 if (alloc->_idx == instance_id) {
2640 // Can not bypass initialization of the instance we are looking for.
2641 return false;
2642 }
2643 // Otherwise skip it.
2644 InitializeNode* init = alloc->initialization();
2645 if (init != NULL)
2646 *np = init->in(TypeFunc::Memory);
2647 else
2648 *np = alloc->in(TypeFunc::Memory);
2649 return true;
2650 }
2652 //----------------------------clear_memory-------------------------------------
2653 // Generate code to initialize object storage to zero.
2654 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2655 intptr_t start_offset,
2656 Node* end_offset,
2657 PhaseGVN* phase) {
2658 Compile* C = phase->C;
2659 intptr_t offset = start_offset;
2661 int unit = BytesPerLong;
2662 if ((offset % unit) != 0) {
2663 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2664 adr = phase->transform(adr);
2665 const TypePtr* atp = TypeRawPtr::BOTTOM;
2666 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2667 mem = phase->transform(mem);
2668 offset += BytesPerInt;
2669 }
2670 assert((offset % unit) == 0, "");
2672 // Initialize the remaining stuff, if any, with a ClearArray.
2673 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2674 }
2676 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2677 Node* start_offset,
2678 Node* end_offset,
2679 PhaseGVN* phase) {
2680 if (start_offset == end_offset) {
2681 // nothing to do
2682 return mem;
2683 }
2685 Compile* C = phase->C;
2686 int unit = BytesPerLong;
2687 Node* zbase = start_offset;
2688 Node* zend = end_offset;
2690 // Scale to the unit required by the CPU:
2691 if (!Matcher::init_array_count_is_in_bytes) {
2692 Node* shift = phase->intcon(exact_log2(unit));
2693 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2694 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2695 }
2697 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2698 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2700 // Bulk clear double-words
2701 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2702 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2703 return phase->transform(mem);
2704 }
2706 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2707 intptr_t start_offset,
2708 intptr_t end_offset,
2709 PhaseGVN* phase) {
2710 if (start_offset == end_offset) {
2711 // nothing to do
2712 return mem;
2713 }
2715 Compile* C = phase->C;
2716 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2717 intptr_t done_offset = end_offset;
2718 if ((done_offset % BytesPerLong) != 0) {
2719 done_offset -= BytesPerInt;
2720 }
2721 if (done_offset > start_offset) {
2722 mem = clear_memory(ctl, mem, dest,
2723 start_offset, phase->MakeConX(done_offset), phase);
2724 }
2725 if (done_offset < end_offset) { // emit the final 32-bit store
2726 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2727 adr = phase->transform(adr);
2728 const TypePtr* atp = TypeRawPtr::BOTTOM;
2729 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2730 mem = phase->transform(mem);
2731 done_offset += BytesPerInt;
2732 }
2733 assert(done_offset == end_offset, "");
2734 return mem;
2735 }
2737 //=============================================================================
2738 // Do not match memory edge.
2739 uint StrIntrinsicNode::match_edge(uint idx) const {
2740 return idx == 2 || idx == 3;
2741 }
2743 //------------------------------Ideal------------------------------------------
2744 // Return a node which is more "ideal" than the current node. Strip out
2745 // control copies
2746 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2747 if (remove_dead_region(phase, can_reshape)) return this;
2748 // Don't bother trying to transform a dead node
2749 if (in(0) && in(0)->is_top()) return NULL;
2751 if (can_reshape) {
2752 Node* mem = phase->transform(in(MemNode::Memory));
2753 // If transformed to a MergeMem, get the desired slice
2754 uint alias_idx = phase->C->get_alias_index(adr_type());
2755 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2756 if (mem != in(MemNode::Memory)) {
2757 set_req(MemNode::Memory, mem);
2758 return this;
2759 }
2760 }
2761 return NULL;
2762 }
2764 //------------------------------Value------------------------------------------
2765 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2766 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2767 return bottom_type();
2768 }
2770 //=============================================================================
2771 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2772 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2773 _adr_type(C->get_adr_type(alias_idx))
2774 {
2775 init_class_id(Class_MemBar);
2776 Node* top = C->top();
2777 init_req(TypeFunc::I_O,top);
2778 init_req(TypeFunc::FramePtr,top);
2779 init_req(TypeFunc::ReturnAdr,top);
2780 if (precedent != NULL)
2781 init_req(TypeFunc::Parms, precedent);
2782 }
2784 //------------------------------cmp--------------------------------------------
2785 uint MemBarNode::hash() const { return NO_HASH; }
2786 uint MemBarNode::cmp( const Node &n ) const {
2787 return (&n == this); // Always fail except on self
2788 }
2790 //------------------------------make-------------------------------------------
2791 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2792 int len = Precedent + (pn == NULL? 0: 1);
2793 switch (opcode) {
2794 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2795 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2796 case Op_MemBarAcquireLock: return new(C, len) MemBarAcquireLockNode(C, atp, pn);
2797 case Op_MemBarReleaseLock: return new(C, len) MemBarReleaseLockNode(C, atp, pn);
2798 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2799 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2800 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2801 case Op_MemBarStoreStore: return new(C, len) MemBarStoreStoreNode(C, atp, pn);
2802 default: ShouldNotReachHere(); return NULL;
2803 }
2804 }
2806 //------------------------------Ideal------------------------------------------
2807 // Return a node which is more "ideal" than the current node. Strip out
2808 // control copies
2809 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2810 if (remove_dead_region(phase, can_reshape)) return this;
2811 // Don't bother trying to transform a dead node
2812 if (in(0) && in(0)->is_top()) return NULL;
2814 // Eliminate volatile MemBars for scalar replaced objects.
2815 if (can_reshape && req() == (Precedent+1) &&
2816 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2817 // Volatile field loads and stores.
2818 Node* my_mem = in(MemBarNode::Precedent);
2819 if (my_mem != NULL && my_mem->is_Mem()) {
2820 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2821 // Check for scalar replaced object reference.
2822 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2823 t_oop->offset() != Type::OffsetBot &&
2824 t_oop->offset() != Type::OffsetTop) {
2825 // Replace MemBar projections by its inputs.
2826 PhaseIterGVN* igvn = phase->is_IterGVN();
2827 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2828 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2829 // Must return either the original node (now dead) or a new node
2830 // (Do not return a top here, since that would break the uniqueness of top.)
2831 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2832 }
2833 }
2834 }
2835 return NULL;
2836 }
2838 //------------------------------Value------------------------------------------
2839 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2840 if( !in(0) ) return Type::TOP;
2841 if( phase->type(in(0)) == Type::TOP )
2842 return Type::TOP;
2843 return TypeTuple::MEMBAR;
2844 }
2846 //------------------------------match------------------------------------------
2847 // Construct projections for memory.
2848 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2849 switch (proj->_con) {
2850 case TypeFunc::Control:
2851 case TypeFunc::Memory:
2852 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2853 }
2854 ShouldNotReachHere();
2855 return NULL;
2856 }
2858 //===========================InitializeNode====================================
2859 // SUMMARY:
2860 // This node acts as a memory barrier on raw memory, after some raw stores.
2861 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2862 // The Initialize can 'capture' suitably constrained stores as raw inits.
2863 // It can coalesce related raw stores into larger units (called 'tiles').
2864 // It can avoid zeroing new storage for memory units which have raw inits.
2865 // At macro-expansion, it is marked 'complete', and does not optimize further.
2866 //
2867 // EXAMPLE:
2868 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2869 // ctl = incoming control; mem* = incoming memory
2870 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2871 // First allocate uninitialized memory and fill in the header:
2872 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2873 // ctl := alloc.Control; mem* := alloc.Memory*
2874 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2875 // Then initialize to zero the non-header parts of the raw memory block:
2876 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2877 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2878 // After the initialize node executes, the object is ready for service:
2879 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2880 // Suppose its body is immediately initialized as {1,2}:
2881 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2882 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2883 // mem.SLICE(#short[*]) := store2
2884 //
2885 // DETAILS:
2886 // An InitializeNode collects and isolates object initialization after
2887 // an AllocateNode and before the next possible safepoint. As a
2888 // memory barrier (MemBarNode), it keeps critical stores from drifting
2889 // down past any safepoint or any publication of the allocation.
2890 // Before this barrier, a newly-allocated object may have uninitialized bits.
2891 // After this barrier, it may be treated as a real oop, and GC is allowed.
2892 //
2893 // The semantics of the InitializeNode include an implicit zeroing of
2894 // the new object from object header to the end of the object.
2895 // (The object header and end are determined by the AllocateNode.)
2896 //
2897 // Certain stores may be added as direct inputs to the InitializeNode.
2898 // These stores must update raw memory, and they must be to addresses
2899 // derived from the raw address produced by AllocateNode, and with
2900 // a constant offset. They must be ordered by increasing offset.
2901 // The first one is at in(RawStores), the last at in(req()-1).
2902 // Unlike most memory operations, they are not linked in a chain,
2903 // but are displayed in parallel as users of the rawmem output of
2904 // the allocation.
2905 //
2906 // (See comments in InitializeNode::capture_store, which continue
2907 // the example given above.)
2908 //
2909 // When the associated Allocate is macro-expanded, the InitializeNode
2910 // may be rewritten to optimize collected stores. A ClearArrayNode
2911 // may also be created at that point to represent any required zeroing.
2912 // The InitializeNode is then marked 'complete', prohibiting further
2913 // capturing of nearby memory operations.
2914 //
2915 // During macro-expansion, all captured initializations which store
2916 // constant values of 32 bits or smaller are coalesced (if advantageous)
2917 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2918 // initialized in fewer memory operations. Memory words which are
2919 // covered by neither tiles nor non-constant stores are pre-zeroed
2920 // by explicit stores of zero. (The code shape happens to do all
2921 // zeroing first, then all other stores, with both sequences occurring
2922 // in order of ascending offsets.)
2923 //
2924 // Alternatively, code may be inserted between an AllocateNode and its
2925 // InitializeNode, to perform arbitrary initialization of the new object.
2926 // E.g., the object copying intrinsics insert complex data transfers here.
2927 // The initialization must then be marked as 'complete' disable the
2928 // built-in zeroing semantics and the collection of initializing stores.
2929 //
2930 // While an InitializeNode is incomplete, reads from the memory state
2931 // produced by it are optimizable if they match the control edge and
2932 // new oop address associated with the allocation/initialization.
2933 // They return a stored value (if the offset matches) or else zero.
2934 // A write to the memory state, if it matches control and address,
2935 // and if it is to a constant offset, may be 'captured' by the
2936 // InitializeNode. It is cloned as a raw memory operation and rewired
2937 // inside the initialization, to the raw oop produced by the allocation.
2938 // Operations on addresses which are provably distinct (e.g., to
2939 // other AllocateNodes) are allowed to bypass the initialization.
2940 //
2941 // The effect of all this is to consolidate object initialization
2942 // (both arrays and non-arrays, both piecewise and bulk) into a
2943 // single location, where it can be optimized as a unit.
2944 //
2945 // Only stores with an offset less than TrackedInitializationLimit words
2946 // will be considered for capture by an InitializeNode. This puts a
2947 // reasonable limit on the complexity of optimized initializations.
2949 //---------------------------InitializeNode------------------------------------
2950 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2951 : _is_complete(Incomplete), _does_not_escape(false),
2952 MemBarNode(C, adr_type, rawoop)
2953 {
2954 init_class_id(Class_Initialize);
2956 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2957 assert(in(RawAddress) == rawoop, "proper init");
2958 // Note: allocation() can be NULL, for secondary initialization barriers
2959 }
2961 // Since this node is not matched, it will be processed by the
2962 // register allocator. Declare that there are no constraints
2963 // on the allocation of the RawAddress edge.
2964 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2965 // This edge should be set to top, by the set_complete. But be conservative.
2966 if (idx == InitializeNode::RawAddress)
2967 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2968 return RegMask::Empty;
2969 }
2971 Node* InitializeNode::memory(uint alias_idx) {
2972 Node* mem = in(Memory);
2973 if (mem->is_MergeMem()) {
2974 return mem->as_MergeMem()->memory_at(alias_idx);
2975 } else {
2976 // incoming raw memory is not split
2977 return mem;
2978 }
2979 }
2981 bool InitializeNode::is_non_zero() {
2982 if (is_complete()) return false;
2983 remove_extra_zeroes();
2984 return (req() > RawStores);
2985 }
2987 void InitializeNode::set_complete(PhaseGVN* phase) {
2988 assert(!is_complete(), "caller responsibility");
2989 _is_complete = Complete;
2991 // After this node is complete, it contains a bunch of
2992 // raw-memory initializations. There is no need for
2993 // it to have anything to do with non-raw memory effects.
2994 // Therefore, tell all non-raw users to re-optimize themselves,
2995 // after skipping the memory effects of this initialization.
2996 PhaseIterGVN* igvn = phase->is_IterGVN();
2997 if (igvn) igvn->add_users_to_worklist(this);
2998 }
3000 // convenience function
3001 // return false if the init contains any stores already
3002 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
3003 InitializeNode* init = initialization();
3004 if (init == NULL || init->is_complete()) return false;
3005 init->remove_extra_zeroes();
3006 // for now, if this allocation has already collected any inits, bail:
3007 if (init->is_non_zero()) return false;
3008 init->set_complete(phase);
3009 return true;
3010 }
3012 void InitializeNode::remove_extra_zeroes() {
3013 if (req() == RawStores) return;
3014 Node* zmem = zero_memory();
3015 uint fill = RawStores;
3016 for (uint i = fill; i < req(); i++) {
3017 Node* n = in(i);
3018 if (n->is_top() || n == zmem) continue; // skip
3019 if (fill < i) set_req(fill, n); // compact
3020 ++fill;
3021 }
3022 // delete any empty spaces created:
3023 while (fill < req()) {
3024 del_req(fill);
3025 }
3026 }
3028 // Helper for remembering which stores go with which offsets.
3029 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
3030 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
3031 intptr_t offset = -1;
3032 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
3033 phase, offset);
3034 if (base == NULL) return -1; // something is dead,
3035 if (offset < 0) return -1; // dead, dead
3036 return offset;
3037 }
3039 // Helper for proving that an initialization expression is
3040 // "simple enough" to be folded into an object initialization.
3041 // Attempts to prove that a store's initial value 'n' can be captured
3042 // within the initialization without creating a vicious cycle, such as:
3043 // { Foo p = new Foo(); p.next = p; }
3044 // True for constants and parameters and small combinations thereof.
3045 bool InitializeNode::detect_init_independence(Node* n,
3046 bool st_is_pinned,
3047 int& count) {
3048 if (n == NULL) return true; // (can this really happen?)
3049 if (n->is_Proj()) n = n->in(0);
3050 if (n == this) return false; // found a cycle
3051 if (n->is_Con()) return true;
3052 if (n->is_Start()) return true; // params, etc., are OK
3053 if (n->is_Root()) return true; // even better
3055 Node* ctl = n->in(0);
3056 if (ctl != NULL && !ctl->is_top()) {
3057 if (ctl->is_Proj()) ctl = ctl->in(0);
3058 if (ctl == this) return false;
3060 // If we already know that the enclosing memory op is pinned right after
3061 // the init, then any control flow that the store has picked up
3062 // must have preceded the init, or else be equal to the init.
3063 // Even after loop optimizations (which might change control edges)
3064 // a store is never pinned *before* the availability of its inputs.
3065 if (!MemNode::all_controls_dominate(n, this))
3066 return false; // failed to prove a good control
3068 }
3070 // Check data edges for possible dependencies on 'this'.
3071 if ((count += 1) > 20) return false; // complexity limit
3072 for (uint i = 1; i < n->req(); i++) {
3073 Node* m = n->in(i);
3074 if (m == NULL || m == n || m->is_top()) continue;
3075 uint first_i = n->find_edge(m);
3076 if (i != first_i) continue; // process duplicate edge just once
3077 if (!detect_init_independence(m, st_is_pinned, count)) {
3078 return false;
3079 }
3080 }
3082 return true;
3083 }
3085 // Here are all the checks a Store must pass before it can be moved into
3086 // an initialization. Returns zero if a check fails.
3087 // On success, returns the (constant) offset to which the store applies,
3088 // within the initialized memory.
3089 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
3090 const int FAIL = 0;
3091 if (st->req() != MemNode::ValueIn + 1)
3092 return FAIL; // an inscrutable StoreNode (card mark?)
3093 Node* ctl = st->in(MemNode::Control);
3094 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3095 return FAIL; // must be unconditional after the initialization
3096 Node* mem = st->in(MemNode::Memory);
3097 if (!(mem->is_Proj() && mem->in(0) == this))
3098 return FAIL; // must not be preceded by other stores
3099 Node* adr = st->in(MemNode::Address);
3100 intptr_t offset;
3101 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3102 if (alloc == NULL)
3103 return FAIL; // inscrutable address
3104 if (alloc != allocation())
3105 return FAIL; // wrong allocation! (store needs to float up)
3106 Node* val = st->in(MemNode::ValueIn);
3107 int complexity_count = 0;
3108 if (!detect_init_independence(val, true, complexity_count))
3109 return FAIL; // stored value must be 'simple enough'
3111 return offset; // success
3112 }
3114 // Find the captured store in(i) which corresponds to the range
3115 // [start..start+size) in the initialized object.
3116 // If there is one, return its index i. If there isn't, return the
3117 // negative of the index where it should be inserted.
3118 // Return 0 if the queried range overlaps an initialization boundary
3119 // or if dead code is encountered.
3120 // If size_in_bytes is zero, do not bother with overlap checks.
3121 int InitializeNode::captured_store_insertion_point(intptr_t start,
3122 int size_in_bytes,
3123 PhaseTransform* phase) {
3124 const int FAIL = 0, MAX_STORE = BytesPerLong;
3126 if (is_complete())
3127 return FAIL; // arraycopy got here first; punt
3129 assert(allocation() != NULL, "must be present");
3131 // no negatives, no header fields:
3132 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3134 // after a certain size, we bail out on tracking all the stores:
3135 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3136 if (start >= ti_limit) return FAIL;
3138 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3139 if (i >= limit) return -(int)i; // not found; here is where to put it
3141 Node* st = in(i);
3142 intptr_t st_off = get_store_offset(st, phase);
3143 if (st_off < 0) {
3144 if (st != zero_memory()) {
3145 return FAIL; // bail out if there is dead garbage
3146 }
3147 } else if (st_off > start) {
3148 // ...we are done, since stores are ordered
3149 if (st_off < start + size_in_bytes) {
3150 return FAIL; // the next store overlaps
3151 }
3152 return -(int)i; // not found; here is where to put it
3153 } else if (st_off < start) {
3154 if (size_in_bytes != 0 &&
3155 start < st_off + MAX_STORE &&
3156 start < st_off + st->as_Store()->memory_size()) {
3157 return FAIL; // the previous store overlaps
3158 }
3159 } else {
3160 if (size_in_bytes != 0 &&
3161 st->as_Store()->memory_size() != size_in_bytes) {
3162 return FAIL; // mismatched store size
3163 }
3164 return i;
3165 }
3167 ++i;
3168 }
3169 }
3171 // Look for a captured store which initializes at the offset 'start'
3172 // with the given size. If there is no such store, and no other
3173 // initialization interferes, then return zero_memory (the memory
3174 // projection of the AllocateNode).
3175 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3176 PhaseTransform* phase) {
3177 assert(stores_are_sane(phase), "");
3178 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3179 if (i == 0) {
3180 return NULL; // something is dead
3181 } else if (i < 0) {
3182 return zero_memory(); // just primordial zero bits here
3183 } else {
3184 Node* st = in(i); // here is the store at this position
3185 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3186 return st;
3187 }
3188 }
3190 // Create, as a raw pointer, an address within my new object at 'offset'.
3191 Node* InitializeNode::make_raw_address(intptr_t offset,
3192 PhaseTransform* phase) {
3193 Node* addr = in(RawAddress);
3194 if (offset != 0) {
3195 Compile* C = phase->C;
3196 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3197 phase->MakeConX(offset)) );
3198 }
3199 return addr;
3200 }
3202 // Clone the given store, converting it into a raw store
3203 // initializing a field or element of my new object.
3204 // Caller is responsible for retiring the original store,
3205 // with subsume_node or the like.
3206 //
3207 // From the example above InitializeNode::InitializeNode,
3208 // here are the old stores to be captured:
3209 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3210 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3211 //
3212 // Here is the changed code; note the extra edges on init:
3213 // alloc = (Allocate ...)
3214 // rawoop = alloc.RawAddress
3215 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3216 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3217 // init = (Initialize alloc.Control alloc.Memory rawoop
3218 // rawstore1 rawstore2)
3219 //
3220 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3221 PhaseTransform* phase) {
3222 assert(stores_are_sane(phase), "");
3224 if (start < 0) return NULL;
3225 assert(can_capture_store(st, phase) == start, "sanity");
3227 Compile* C = phase->C;
3228 int size_in_bytes = st->memory_size();
3229 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3230 if (i == 0) return NULL; // bail out
3231 Node* prev_mem = NULL; // raw memory for the captured store
3232 if (i > 0) {
3233 prev_mem = in(i); // there is a pre-existing store under this one
3234 set_req(i, C->top()); // temporarily disconnect it
3235 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3236 } else {
3237 i = -i; // no pre-existing store
3238 prev_mem = zero_memory(); // a slice of the newly allocated object
3239 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3240 set_req(--i, C->top()); // reuse this edge; it has been folded away
3241 else
3242 ins_req(i, C->top()); // build a new edge
3243 }
3244 Node* new_st = st->clone();
3245 new_st->set_req(MemNode::Control, in(Control));
3246 new_st->set_req(MemNode::Memory, prev_mem);
3247 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3248 new_st = phase->transform(new_st);
3250 // At this point, new_st might have swallowed a pre-existing store
3251 // at the same offset, or perhaps new_st might have disappeared,
3252 // if it redundantly stored the same value (or zero to fresh memory).
3254 // In any case, wire it in:
3255 set_req(i, new_st);
3257 // The caller may now kill the old guy.
3258 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3259 assert(check_st == new_st || check_st == NULL, "must be findable");
3260 assert(!is_complete(), "");
3261 return new_st;
3262 }
3264 static bool store_constant(jlong* tiles, int num_tiles,
3265 intptr_t st_off, int st_size,
3266 jlong con) {
3267 if ((st_off & (st_size-1)) != 0)
3268 return false; // strange store offset (assume size==2**N)
3269 address addr = (address)tiles + st_off;
3270 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3271 switch (st_size) {
3272 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3273 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3274 case sizeof(jint): *(jint*) addr = (jint) con; break;
3275 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3276 default: return false; // strange store size (detect size!=2**N here)
3277 }
3278 return true; // return success to caller
3279 }
3281 // Coalesce subword constants into int constants and possibly
3282 // into long constants. The goal, if the CPU permits,
3283 // is to initialize the object with a small number of 64-bit tiles.
3284 // Also, convert floating-point constants to bit patterns.
3285 // Non-constants are not relevant to this pass.
3286 //
3287 // In terms of the running example on InitializeNode::InitializeNode
3288 // and InitializeNode::capture_store, here is the transformation
3289 // of rawstore1 and rawstore2 into rawstore12:
3290 // alloc = (Allocate ...)
3291 // rawoop = alloc.RawAddress
3292 // tile12 = 0x00010002
3293 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3294 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3295 //
3296 void
3297 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3298 Node* size_in_bytes,
3299 PhaseGVN* phase) {
3300 Compile* C = phase->C;
3302 assert(stores_are_sane(phase), "");
3303 // Note: After this pass, they are not completely sane,
3304 // since there may be some overlaps.
3306 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3308 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3309 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3310 size_limit = MIN2(size_limit, ti_limit);
3311 size_limit = align_size_up(size_limit, BytesPerLong);
3312 int num_tiles = size_limit / BytesPerLong;
3314 // allocate space for the tile map:
3315 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3316 jlong tiles_buf[small_len];
3317 Node* nodes_buf[small_len];
3318 jlong inits_buf[small_len];
3319 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3320 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3321 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3322 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3323 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3324 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3325 // tiles: exact bitwise model of all primitive constants
3326 // nodes: last constant-storing node subsumed into the tiles model
3327 // inits: which bytes (in each tile) are touched by any initializations
3329 //// Pass A: Fill in the tile model with any relevant stores.
3331 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3332 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3333 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3334 Node* zmem = zero_memory(); // initially zero memory state
3335 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3336 Node* st = in(i);
3337 intptr_t st_off = get_store_offset(st, phase);
3339 // Figure out the store's offset and constant value:
3340 if (st_off < header_size) continue; //skip (ignore header)
3341 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3342 int st_size = st->as_Store()->memory_size();
3343 if (st_off + st_size > size_limit) break;
3345 // Record which bytes are touched, whether by constant or not.
3346 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3347 continue; // skip (strange store size)
3349 const Type* val = phase->type(st->in(MemNode::ValueIn));
3350 if (!val->singleton()) continue; //skip (non-con store)
3351 BasicType type = val->basic_type();
3353 jlong con = 0;
3354 switch (type) {
3355 case T_INT: con = val->is_int()->get_con(); break;
3356 case T_LONG: con = val->is_long()->get_con(); break;
3357 case T_FLOAT: con = jint_cast(val->getf()); break;
3358 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3359 default: continue; //skip (odd store type)
3360 }
3362 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3363 st->Opcode() == Op_StoreL) {
3364 continue; // This StoreL is already optimal.
3365 }
3367 // Store down the constant.
3368 store_constant(tiles, num_tiles, st_off, st_size, con);
3370 intptr_t j = st_off >> LogBytesPerLong;
3372 if (type == T_INT && st_size == BytesPerInt
3373 && (st_off & BytesPerInt) == BytesPerInt) {
3374 jlong lcon = tiles[j];
3375 if (!Matcher::isSimpleConstant64(lcon) &&
3376 st->Opcode() == Op_StoreI) {
3377 // This StoreI is already optimal by itself.
3378 jint* intcon = (jint*) &tiles[j];
3379 intcon[1] = 0; // undo the store_constant()
3381 // If the previous store is also optimal by itself, back up and
3382 // undo the action of the previous loop iteration... if we can.
3383 // But if we can't, just let the previous half take care of itself.
3384 st = nodes[j];
3385 st_off -= BytesPerInt;
3386 con = intcon[0];
3387 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3388 assert(st_off >= header_size, "still ignoring header");
3389 assert(get_store_offset(st, phase) == st_off, "must be");
3390 assert(in(i-1) == zmem, "must be");
3391 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3392 assert(con == tcon->is_int()->get_con(), "must be");
3393 // Undo the effects of the previous loop trip, which swallowed st:
3394 intcon[0] = 0; // undo store_constant()
3395 set_req(i-1, st); // undo set_req(i, zmem)
3396 nodes[j] = NULL; // undo nodes[j] = st
3397 --old_subword; // undo ++old_subword
3398 }
3399 continue; // This StoreI is already optimal.
3400 }
3401 }
3403 // This store is not needed.
3404 set_req(i, zmem);
3405 nodes[j] = st; // record for the moment
3406 if (st_size < BytesPerLong) // something has changed
3407 ++old_subword; // includes int/float, but who's counting...
3408 else ++old_long;
3409 }
3411 if ((old_subword + old_long) == 0)
3412 return; // nothing more to do
3414 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3415 // Be sure to insert them before overlapping non-constant stores.
3416 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3417 for (int j = 0; j < num_tiles; j++) {
3418 jlong con = tiles[j];
3419 jlong init = inits[j];
3420 if (con == 0) continue;
3421 jint con0, con1; // split the constant, address-wise
3422 jint init0, init1; // split the init map, address-wise
3423 { union { jlong con; jint intcon[2]; } u;
3424 u.con = con;
3425 con0 = u.intcon[0];
3426 con1 = u.intcon[1];
3427 u.con = init;
3428 init0 = u.intcon[0];
3429 init1 = u.intcon[1];
3430 }
3432 Node* old = nodes[j];
3433 assert(old != NULL, "need the prior store");
3434 intptr_t offset = (j * BytesPerLong);
3436 bool split = !Matcher::isSimpleConstant64(con);
3438 if (offset < header_size) {
3439 assert(offset + BytesPerInt >= header_size, "second int counts");
3440 assert(*(jint*)&tiles[j] == 0, "junk in header");
3441 split = true; // only the second word counts
3442 // Example: int a[] = { 42 ... }
3443 } else if (con0 == 0 && init0 == -1) {
3444 split = true; // first word is covered by full inits
3445 // Example: int a[] = { ... foo(), 42 ... }
3446 } else if (con1 == 0 && init1 == -1) {
3447 split = true; // second word is covered by full inits
3448 // Example: int a[] = { ... 42, foo() ... }
3449 }
3451 // Here's a case where init0 is neither 0 nor -1:
3452 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3453 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3454 // In this case the tile is not split; it is (jlong)42.
3455 // The big tile is stored down, and then the foo() value is inserted.
3456 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3458 Node* ctl = old->in(MemNode::Control);
3459 Node* adr = make_raw_address(offset, phase);
3460 const TypePtr* atp = TypeRawPtr::BOTTOM;
3462 // One or two coalesced stores to plop down.
3463 Node* st[2];
3464 intptr_t off[2];
3465 int nst = 0;
3466 if (!split) {
3467 ++new_long;
3468 off[nst] = offset;
3469 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3470 phase->longcon(con), T_LONG);
3471 } else {
3472 // Omit either if it is a zero.
3473 if (con0 != 0) {
3474 ++new_int;
3475 off[nst] = offset;
3476 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3477 phase->intcon(con0), T_INT);
3478 }
3479 if (con1 != 0) {
3480 ++new_int;
3481 offset += BytesPerInt;
3482 adr = make_raw_address(offset, phase);
3483 off[nst] = offset;
3484 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3485 phase->intcon(con1), T_INT);
3486 }
3487 }
3489 // Insert second store first, then the first before the second.
3490 // Insert each one just before any overlapping non-constant stores.
3491 while (nst > 0) {
3492 Node* st1 = st[--nst];
3493 C->copy_node_notes_to(st1, old);
3494 st1 = phase->transform(st1);
3495 offset = off[nst];
3496 assert(offset >= header_size, "do not smash header");
3497 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3498 guarantee(ins_idx != 0, "must re-insert constant store");
3499 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3500 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3501 set_req(--ins_idx, st1);
3502 else
3503 ins_req(ins_idx, st1);
3504 }
3505 }
3507 if (PrintCompilation && WizardMode)
3508 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3509 old_subword, old_long, new_int, new_long);
3510 if (C->log() != NULL)
3511 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3512 old_subword, old_long, new_int, new_long);
3514 // Clean up any remaining occurrences of zmem:
3515 remove_extra_zeroes();
3516 }
3518 // Explore forward from in(start) to find the first fully initialized
3519 // word, and return its offset. Skip groups of subword stores which
3520 // together initialize full words. If in(start) is itself part of a
3521 // fully initialized word, return the offset of in(start). If there
3522 // are no following full-word stores, or if something is fishy, return
3523 // a negative value.
3524 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3525 int int_map = 0;
3526 intptr_t int_map_off = 0;
3527 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3529 for (uint i = start, limit = req(); i < limit; i++) {
3530 Node* st = in(i);
3532 intptr_t st_off = get_store_offset(st, phase);
3533 if (st_off < 0) break; // return conservative answer
3535 int st_size = st->as_Store()->memory_size();
3536 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3537 return st_off; // we found a complete word init
3538 }
3540 // update the map:
3542 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3543 if (this_int_off != int_map_off) {
3544 // reset the map:
3545 int_map = 0;
3546 int_map_off = this_int_off;
3547 }
3549 int subword_off = st_off - this_int_off;
3550 int_map |= right_n_bits(st_size) << subword_off;
3551 if ((int_map & FULL_MAP) == FULL_MAP) {
3552 return this_int_off; // we found a complete word init
3553 }
3555 // Did this store hit or cross the word boundary?
3556 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3557 if (next_int_off == this_int_off + BytesPerInt) {
3558 // We passed the current int, without fully initializing it.
3559 int_map_off = next_int_off;
3560 int_map >>= BytesPerInt;
3561 } else if (next_int_off > this_int_off + BytesPerInt) {
3562 // We passed the current and next int.
3563 return this_int_off + BytesPerInt;
3564 }
3565 }
3567 return -1;
3568 }
3571 // Called when the associated AllocateNode is expanded into CFG.
3572 // At this point, we may perform additional optimizations.
3573 // Linearize the stores by ascending offset, to make memory
3574 // activity as coherent as possible.
3575 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3576 intptr_t header_size,
3577 Node* size_in_bytes,
3578 PhaseGVN* phase) {
3579 assert(!is_complete(), "not already complete");
3580 assert(stores_are_sane(phase), "");
3581 assert(allocation() != NULL, "must be present");
3583 remove_extra_zeroes();
3585 if (ReduceFieldZeroing || ReduceBulkZeroing)
3586 // reduce instruction count for common initialization patterns
3587 coalesce_subword_stores(header_size, size_in_bytes, phase);
3589 Node* zmem = zero_memory(); // initially zero memory state
3590 Node* inits = zmem; // accumulating a linearized chain of inits
3591 #ifdef ASSERT
3592 intptr_t first_offset = allocation()->minimum_header_size();
3593 intptr_t last_init_off = first_offset; // previous init offset
3594 intptr_t last_init_end = first_offset; // previous init offset+size
3595 intptr_t last_tile_end = first_offset; // previous tile offset+size
3596 #endif
3597 intptr_t zeroes_done = header_size;
3599 bool do_zeroing = true; // we might give up if inits are very sparse
3600 int big_init_gaps = 0; // how many large gaps have we seen?
3602 if (ZeroTLAB) do_zeroing = false;
3603 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3605 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3606 Node* st = in(i);
3607 intptr_t st_off = get_store_offset(st, phase);
3608 if (st_off < 0)
3609 break; // unknown junk in the inits
3610 if (st->in(MemNode::Memory) != zmem)
3611 break; // complicated store chains somehow in list
3613 int st_size = st->as_Store()->memory_size();
3614 intptr_t next_init_off = st_off + st_size;
3616 if (do_zeroing && zeroes_done < next_init_off) {
3617 // See if this store needs a zero before it or under it.
3618 intptr_t zeroes_needed = st_off;
3620 if (st_size < BytesPerInt) {
3621 // Look for subword stores which only partially initialize words.
3622 // If we find some, we must lay down some word-level zeroes first,
3623 // underneath the subword stores.
3624 //
3625 // Examples:
3626 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3627 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3628 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3629 //
3630 // Note: coalesce_subword_stores may have already done this,
3631 // if it was prompted by constant non-zero subword initializers.
3632 // But this case can still arise with non-constant stores.
3634 intptr_t next_full_store = find_next_fullword_store(i, phase);
3636 // In the examples above:
3637 // in(i) p q r s x y z
3638 // st_off 12 13 14 15 12 13 14
3639 // st_size 1 1 1 1 1 1 1
3640 // next_full_s. 12 16 16 16 16 16 16
3641 // z's_done 12 16 16 16 12 16 12
3642 // z's_needed 12 16 16 16 16 16 16
3643 // zsize 0 0 0 0 4 0 4
3644 if (next_full_store < 0) {
3645 // Conservative tack: Zero to end of current word.
3646 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3647 } else {
3648 // Zero to beginning of next fully initialized word.
3649 // Or, don't zero at all, if we are already in that word.
3650 assert(next_full_store >= zeroes_needed, "must go forward");
3651 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3652 zeroes_needed = next_full_store;
3653 }
3654 }
3656 if (zeroes_needed > zeroes_done) {
3657 intptr_t zsize = zeroes_needed - zeroes_done;
3658 // Do some incremental zeroing on rawmem, in parallel with inits.
3659 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3660 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3661 zeroes_done, zeroes_needed,
3662 phase);
3663 zeroes_done = zeroes_needed;
3664 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3665 do_zeroing = false; // leave the hole, next time
3666 }
3667 }
3669 // Collect the store and move on:
3670 st->set_req(MemNode::Memory, inits);
3671 inits = st; // put it on the linearized chain
3672 set_req(i, zmem); // unhook from previous position
3674 if (zeroes_done == st_off)
3675 zeroes_done = next_init_off;
3677 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3679 #ifdef ASSERT
3680 // Various order invariants. Weaker than stores_are_sane because
3681 // a large constant tile can be filled in by smaller non-constant stores.
3682 assert(st_off >= last_init_off, "inits do not reverse");
3683 last_init_off = st_off;
3684 const Type* val = NULL;
3685 if (st_size >= BytesPerInt &&
3686 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3687 (int)val->basic_type() < (int)T_OBJECT) {
3688 assert(st_off >= last_tile_end, "tiles do not overlap");
3689 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3690 last_tile_end = MAX2(last_tile_end, next_init_off);
3691 } else {
3692 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3693 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3694 assert(st_off >= last_init_end, "inits do not overlap");
3695 last_init_end = next_init_off; // it's a non-tile
3696 }
3697 #endif //ASSERT
3698 }
3700 remove_extra_zeroes(); // clear out all the zmems left over
3701 add_req(inits);
3703 if (!ZeroTLAB) {
3704 // If anything remains to be zeroed, zero it all now.
3705 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3706 // if it is the last unused 4 bytes of an instance, forget about it
3707 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3708 if (zeroes_done + BytesPerLong >= size_limit) {
3709 assert(allocation() != NULL, "");
3710 if (allocation()->Opcode() == Op_Allocate) {
3711 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3712 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3713 if (zeroes_done == k->layout_helper())
3714 zeroes_done = size_limit;
3715 }
3716 }
3717 if (zeroes_done < size_limit) {
3718 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3719 zeroes_done, size_in_bytes, phase);
3720 }
3721 }
3723 set_complete(phase);
3724 return rawmem;
3725 }
3728 #ifdef ASSERT
3729 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3730 if (is_complete())
3731 return true; // stores could be anything at this point
3732 assert(allocation() != NULL, "must be present");
3733 intptr_t last_off = allocation()->minimum_header_size();
3734 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3735 Node* st = in(i);
3736 intptr_t st_off = get_store_offset(st, phase);
3737 if (st_off < 0) continue; // ignore dead garbage
3738 if (last_off > st_off) {
3739 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3740 this->dump(2);
3741 assert(false, "ascending store offsets");
3742 return false;
3743 }
3744 last_off = st_off + st->as_Store()->memory_size();
3745 }
3746 return true;
3747 }
3748 #endif //ASSERT
3753 //============================MergeMemNode=====================================
3754 //
3755 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3756 // contributing store or call operations. Each contributor provides the memory
3757 // state for a particular "alias type" (see Compile::alias_type). For example,
3758 // if a MergeMem has an input X for alias category #6, then any memory reference
3759 // to alias category #6 may use X as its memory state input, as an exact equivalent
3760 // to using the MergeMem as a whole.
3761 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3762 //
3763 // (Here, the <N> notation gives the index of the relevant adr_type.)
3764 //
3765 // In one special case (and more cases in the future), alias categories overlap.
3766 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3767 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3768 // it is exactly equivalent to that state W:
3769 // MergeMem(<Bot>: W) <==> W
3770 //
3771 // Usually, the merge has more than one input. In that case, where inputs
3772 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3773 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3774 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3775 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3776 //
3777 // A merge can take a "wide" memory state as one of its narrow inputs.
3778 // This simply means that the merge observes out only the relevant parts of
3779 // the wide input. That is, wide memory states arriving at narrow merge inputs
3780 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3781 //
3782 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3783 // and that memory slices "leak through":
3784 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3785 //
3786 // But, in such a cascade, repeated memory slices can "block the leak":
3787 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3788 //
3789 // In the last example, Y is not part of the combined memory state of the
3790 // outermost MergeMem. The system must, of course, prevent unschedulable
3791 // memory states from arising, so you can be sure that the state Y is somehow
3792 // a precursor to state Y'.
3793 //
3794 //
3795 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3796 // of each MergeMemNode array are exactly the numerical alias indexes, including
3797 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3798 // Compile::alias_type (and kin) produce and manage these indexes.
3799 //
3800 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3801 // (Note that this provides quick access to the top node inside MergeMem methods,
3802 // without the need to reach out via TLS to Compile::current.)
3803 //
3804 // As a consequence of what was just described, a MergeMem that represents a full
3805 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3806 // containing all alias categories.
3807 //
3808 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3809 //
3810 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3811 // a memory state for the alias type <N>, or else the top node, meaning that
3812 // there is no particular input for that alias type. Note that the length of
3813 // a MergeMem is variable, and may be extended at any time to accommodate new
3814 // memory states at larger alias indexes. When merges grow, they are of course
3815 // filled with "top" in the unused in() positions.
3816 //
3817 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3818 // (Top was chosen because it works smoothly with passes like GCM.)
3819 //
3820 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3821 // the type of random VM bits like TLS references.) Since it is always the
3822 // first non-Bot memory slice, some low-level loops use it to initialize an
3823 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3824 //
3825 //
3826 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3827 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3828 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3829 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3830 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3831 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3832 //
3833 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3834 // really that different from the other memory inputs. An abbreviation called
3835 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3836 //
3837 //
3838 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3839 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3840 // that "emerges though" the base memory will be marked as excluding the alias types
3841 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3842 //
3843 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3844 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3845 //
3846 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3847 // (It is currently unimplemented.) As you can see, the resulting merge is
3848 // actually a disjoint union of memory states, rather than an overlay.
3849 //
3851 //------------------------------MergeMemNode-----------------------------------
3852 Node* MergeMemNode::make_empty_memory() {
3853 Node* empty_memory = (Node*) Compile::current()->top();
3854 assert(empty_memory->is_top(), "correct sentinel identity");
3855 return empty_memory;
3856 }
3858 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3859 init_class_id(Class_MergeMem);
3860 // all inputs are nullified in Node::Node(int)
3861 // set_input(0, NULL); // no control input
3863 // Initialize the edges uniformly to top, for starters.
3864 Node* empty_mem = make_empty_memory();
3865 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3866 init_req(i,empty_mem);
3867 }
3868 assert(empty_memory() == empty_mem, "");
3870 if( new_base != NULL && new_base->is_MergeMem() ) {
3871 MergeMemNode* mdef = new_base->as_MergeMem();
3872 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3873 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3874 mms.set_memory(mms.memory2());
3875 }
3876 assert(base_memory() == mdef->base_memory(), "");
3877 } else {
3878 set_base_memory(new_base);
3879 }
3880 }
3882 // Make a new, untransformed MergeMem with the same base as 'mem'.
3883 // If mem is itself a MergeMem, populate the result with the same edges.
3884 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3885 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3886 }
3888 //------------------------------cmp--------------------------------------------
3889 uint MergeMemNode::hash() const { return NO_HASH; }
3890 uint MergeMemNode::cmp( const Node &n ) const {
3891 return (&n == this); // Always fail except on self
3892 }
3894 //------------------------------Identity---------------------------------------
3895 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3896 // Identity if this merge point does not record any interesting memory
3897 // disambiguations.
3898 Node* base_mem = base_memory();
3899 Node* empty_mem = empty_memory();
3900 if (base_mem != empty_mem) { // Memory path is not dead?
3901 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3902 Node* mem = in(i);
3903 if (mem != empty_mem && mem != base_mem) {
3904 return this; // Many memory splits; no change
3905 }
3906 }
3907 }
3908 return base_mem; // No memory splits; ID on the one true input
3909 }
3911 //------------------------------Ideal------------------------------------------
3912 // This method is invoked recursively on chains of MergeMem nodes
3913 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3914 // Remove chain'd MergeMems
3915 //
3916 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3917 // relative to the "in(Bot)". Since we are patching both at the same time,
3918 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3919 // but rewrite each "in(i)" relative to the new "in(Bot)".
3920 Node *progress = NULL;
3923 Node* old_base = base_memory();
3924 Node* empty_mem = empty_memory();
3925 if (old_base == empty_mem)
3926 return NULL; // Dead memory path.
3928 MergeMemNode* old_mbase;
3929 if (old_base != NULL && old_base->is_MergeMem())
3930 old_mbase = old_base->as_MergeMem();
3931 else
3932 old_mbase = NULL;
3933 Node* new_base = old_base;
3935 // simplify stacked MergeMems in base memory
3936 if (old_mbase) new_base = old_mbase->base_memory();
3938 // the base memory might contribute new slices beyond my req()
3939 if (old_mbase) grow_to_match(old_mbase);
3941 // Look carefully at the base node if it is a phi.
3942 PhiNode* phi_base;
3943 if (new_base != NULL && new_base->is_Phi())
3944 phi_base = new_base->as_Phi();
3945 else
3946 phi_base = NULL;
3948 Node* phi_reg = NULL;
3949 uint phi_len = (uint)-1;
3950 if (phi_base != NULL && !phi_base->is_copy()) {
3951 // do not examine phi if degraded to a copy
3952 phi_reg = phi_base->region();
3953 phi_len = phi_base->req();
3954 // see if the phi is unfinished
3955 for (uint i = 1; i < phi_len; i++) {
3956 if (phi_base->in(i) == NULL) {
3957 // incomplete phi; do not look at it yet!
3958 phi_reg = NULL;
3959 phi_len = (uint)-1;
3960 break;
3961 }
3962 }
3963 }
3965 // Note: We do not call verify_sparse on entry, because inputs
3966 // can normalize to the base_memory via subsume_node or similar
3967 // mechanisms. This method repairs that damage.
3969 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3971 // Look at each slice.
3972 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3973 Node* old_in = in(i);
3974 // calculate the old memory value
3975 Node* old_mem = old_in;
3976 if (old_mem == empty_mem) old_mem = old_base;
3977 assert(old_mem == memory_at(i), "");
3979 // maybe update (reslice) the old memory value
3981 // simplify stacked MergeMems
3982 Node* new_mem = old_mem;
3983 MergeMemNode* old_mmem;
3984 if (old_mem != NULL && old_mem->is_MergeMem())
3985 old_mmem = old_mem->as_MergeMem();
3986 else
3987 old_mmem = NULL;
3988 if (old_mmem == this) {
3989 // This can happen if loops break up and safepoints disappear.
3990 // A merge of BotPtr (default) with a RawPtr memory derived from a
3991 // safepoint can be rewritten to a merge of the same BotPtr with
3992 // the BotPtr phi coming into the loop. If that phi disappears
3993 // also, we can end up with a self-loop of the mergemem.
3994 // In general, if loops degenerate and memory effects disappear,
3995 // a mergemem can be left looking at itself. This simply means
3996 // that the mergemem's default should be used, since there is
3997 // no longer any apparent effect on this slice.
3998 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3999 // from start. Update the input to TOP.
4000 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
4001 }
4002 else if (old_mmem != NULL) {
4003 new_mem = old_mmem->memory_at(i);
4004 }
4005 // else preceding memory was not a MergeMem
4007 // replace equivalent phis (unfortunately, they do not GVN together)
4008 if (new_mem != NULL && new_mem != new_base &&
4009 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
4010 if (new_mem->is_Phi()) {
4011 PhiNode* phi_mem = new_mem->as_Phi();
4012 for (uint i = 1; i < phi_len; i++) {
4013 if (phi_base->in(i) != phi_mem->in(i)) {
4014 phi_mem = NULL;
4015 break;
4016 }
4017 }
4018 if (phi_mem != NULL) {
4019 // equivalent phi nodes; revert to the def
4020 new_mem = new_base;
4021 }
4022 }
4023 }
4025 // maybe store down a new value
4026 Node* new_in = new_mem;
4027 if (new_in == new_base) new_in = empty_mem;
4029 if (new_in != old_in) {
4030 // Warning: Do not combine this "if" with the previous "if"
4031 // A memory slice might have be be rewritten even if it is semantically
4032 // unchanged, if the base_memory value has changed.
4033 set_req(i, new_in);
4034 progress = this; // Report progress
4035 }
4036 }
4038 if (new_base != old_base) {
4039 set_req(Compile::AliasIdxBot, new_base);
4040 // Don't use set_base_memory(new_base), because we need to update du.
4041 assert(base_memory() == new_base, "");
4042 progress = this;
4043 }
4045 if( base_memory() == this ) {
4046 // a self cycle indicates this memory path is dead
4047 set_req(Compile::AliasIdxBot, empty_mem);
4048 }
4050 // Resolve external cycles by calling Ideal on a MergeMem base_memory
4051 // Recursion must occur after the self cycle check above
4052 if( base_memory()->is_MergeMem() ) {
4053 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
4054 Node *m = phase->transform(new_mbase); // Rollup any cycles
4055 if( m != NULL && (m->is_top() ||
4056 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
4057 // propagate rollup of dead cycle to self
4058 set_req(Compile::AliasIdxBot, empty_mem);
4059 }
4060 }
4062 if( base_memory() == empty_mem ) {
4063 progress = this;
4064 // Cut inputs during Parse phase only.
4065 // During Optimize phase a dead MergeMem node will be subsumed by Top.
4066 if( !can_reshape ) {
4067 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4068 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
4069 }
4070 }
4071 }
4073 if( !progress && base_memory()->is_Phi() && can_reshape ) {
4074 // Check if PhiNode::Ideal's "Split phis through memory merges"
4075 // transform should be attempted. Look for this->phi->this cycle.
4076 uint merge_width = req();
4077 if (merge_width > Compile::AliasIdxRaw) {
4078 PhiNode* phi = base_memory()->as_Phi();
4079 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
4080 if (phi->in(i) == this) {
4081 phase->is_IterGVN()->_worklist.push(phi);
4082 break;
4083 }
4084 }
4085 }
4086 }
4088 assert(progress || verify_sparse(), "please, no dups of base");
4089 return progress;
4090 }
4092 //-------------------------set_base_memory-------------------------------------
4093 void MergeMemNode::set_base_memory(Node *new_base) {
4094 Node* empty_mem = empty_memory();
4095 set_req(Compile::AliasIdxBot, new_base);
4096 assert(memory_at(req()) == new_base, "must set default memory");
4097 // Clear out other occurrences of new_base:
4098 if (new_base != empty_mem) {
4099 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4100 if (in(i) == new_base) set_req(i, empty_mem);
4101 }
4102 }
4103 }
4105 //------------------------------out_RegMask------------------------------------
4106 const RegMask &MergeMemNode::out_RegMask() const {
4107 return RegMask::Empty;
4108 }
4110 //------------------------------dump_spec--------------------------------------
4111 #ifndef PRODUCT
4112 void MergeMemNode::dump_spec(outputStream *st) const {
4113 st->print(" {");
4114 Node* base_mem = base_memory();
4115 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4116 Node* mem = memory_at(i);
4117 if (mem == base_mem) { st->print(" -"); continue; }
4118 st->print( " N%d:", mem->_idx );
4119 Compile::current()->get_adr_type(i)->dump_on(st);
4120 }
4121 st->print(" }");
4122 }
4123 #endif // !PRODUCT
4126 #ifdef ASSERT
4127 static bool might_be_same(Node* a, Node* b) {
4128 if (a == b) return true;
4129 if (!(a->is_Phi() || b->is_Phi())) return false;
4130 // phis shift around during optimization
4131 return true; // pretty stupid...
4132 }
4134 // verify a narrow slice (either incoming or outgoing)
4135 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4136 if (!VerifyAliases) return; // don't bother to verify unless requested
4137 if (is_error_reported()) return; // muzzle asserts when debugging an error
4138 if (Node::in_dump()) return; // muzzle asserts when printing
4139 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4140 assert(n != NULL, "");
4141 // Elide intervening MergeMem's
4142 while (n->is_MergeMem()) {
4143 n = n->as_MergeMem()->memory_at(alias_idx);
4144 }
4145 Compile* C = Compile::current();
4146 const TypePtr* n_adr_type = n->adr_type();
4147 if (n == m->empty_memory()) {
4148 // Implicit copy of base_memory()
4149 } else if (n_adr_type != TypePtr::BOTTOM) {
4150 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4151 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4152 } else {
4153 // A few places like make_runtime_call "know" that VM calls are narrow,
4154 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4155 bool expected_wide_mem = false;
4156 if (n == m->base_memory()) {
4157 expected_wide_mem = true;
4158 } else if (alias_idx == Compile::AliasIdxRaw ||
4159 n == m->memory_at(Compile::AliasIdxRaw)) {
4160 expected_wide_mem = true;
4161 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4162 // memory can "leak through" calls on channels that
4163 // are write-once. Allow this also.
4164 expected_wide_mem = true;
4165 }
4166 assert(expected_wide_mem, "expected narrow slice replacement");
4167 }
4168 }
4169 #else // !ASSERT
4170 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4171 #endif
4174 //-----------------------------memory_at---------------------------------------
4175 Node* MergeMemNode::memory_at(uint alias_idx) const {
4176 assert(alias_idx >= Compile::AliasIdxRaw ||
4177 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4178 "must avoid base_memory and AliasIdxTop");
4180 // Otherwise, it is a narrow slice.
4181 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4182 Compile *C = Compile::current();
4183 if (is_empty_memory(n)) {
4184 // the array is sparse; empty slots are the "top" node
4185 n = base_memory();
4186 assert(Node::in_dump()
4187 || n == NULL || n->bottom_type() == Type::TOP
4188 || n->adr_type() == NULL // address is TOP
4189 || n->adr_type() == TypePtr::BOTTOM
4190 || n->adr_type() == TypeRawPtr::BOTTOM
4191 || Compile::current()->AliasLevel() == 0,
4192 "must be a wide memory");
4193 // AliasLevel == 0 if we are organizing the memory states manually.
4194 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4195 } else {
4196 // make sure the stored slice is sane
4197 #ifdef ASSERT
4198 if (is_error_reported() || Node::in_dump()) {
4199 } else if (might_be_same(n, base_memory())) {
4200 // Give it a pass: It is a mostly harmless repetition of the base.
4201 // This can arise normally from node subsumption during optimization.
4202 } else {
4203 verify_memory_slice(this, alias_idx, n);
4204 }
4205 #endif
4206 }
4207 return n;
4208 }
4210 //---------------------------set_memory_at-------------------------------------
4211 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4212 verify_memory_slice(this, alias_idx, n);
4213 Node* empty_mem = empty_memory();
4214 if (n == base_memory()) n = empty_mem; // collapse default
4215 uint need_req = alias_idx+1;
4216 if (req() < need_req) {
4217 if (n == empty_mem) return; // already the default, so do not grow me
4218 // grow the sparse array
4219 do {
4220 add_req(empty_mem);
4221 } while (req() < need_req);
4222 }
4223 set_req( alias_idx, n );
4224 }
4228 //--------------------------iteration_setup------------------------------------
4229 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4230 if (other != NULL) {
4231 grow_to_match(other);
4232 // invariant: the finite support of mm2 is within mm->req()
4233 #ifdef ASSERT
4234 for (uint i = req(); i < other->req(); i++) {
4235 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4236 }
4237 #endif
4238 }
4239 // Replace spurious copies of base_memory by top.
4240 Node* base_mem = base_memory();
4241 if (base_mem != NULL && !base_mem->is_top()) {
4242 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4243 if (in(i) == base_mem)
4244 set_req(i, empty_memory());
4245 }
4246 }
4247 }
4249 //---------------------------grow_to_match-------------------------------------
4250 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4251 Node* empty_mem = empty_memory();
4252 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4253 // look for the finite support of the other memory
4254 for (uint i = other->req(); --i >= req(); ) {
4255 if (other->in(i) != empty_mem) {
4256 uint new_len = i+1;
4257 while (req() < new_len) add_req(empty_mem);
4258 break;
4259 }
4260 }
4261 }
4263 //---------------------------verify_sparse-------------------------------------
4264 #ifndef PRODUCT
4265 bool MergeMemNode::verify_sparse() const {
4266 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4267 Node* base_mem = base_memory();
4268 // The following can happen in degenerate cases, since empty==top.
4269 if (is_empty_memory(base_mem)) return true;
4270 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4271 assert(in(i) != NULL, "sane slice");
4272 if (in(i) == base_mem) return false; // should have been the sentinel value!
4273 }
4274 return true;
4275 }
4277 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4278 Node* n;
4279 n = mm->in(idx);
4280 if (mem == n) return true; // might be empty_memory()
4281 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4282 if (mem == n) return true;
4283 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4284 if (mem == n) return true;
4285 if (n == NULL) break;
4286 }
4287 return false;
4288 }
4289 #endif // !PRODUCT