Wed, 14 Sep 2011 09:22:51 +0200
7077312: Provide a CALL effect for instruct declaration in the ad file
Summary: abstracted way to declare that the MachNode has the effect of a call (kills caller save registers, preserves callee save registers)
Reviewed-by: twisti, never
1 /*
2 * Copyright (c) 1997, 2011, 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.
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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.
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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 Node *address = in(MemNode::Address);
269 const Type *t_adr = phase->type( address );
270 if( t_adr == Type::TOP ) return NodeSentinel; // caller will return NULL
272 if( can_reshape && igvn != NULL &&
273 (igvn->_worklist.member(address) ||
274 igvn->_worklist.size() > 0 && (phase->type(address) != adr_type())) ) {
275 // The address's base and type may change when the address is processed.
276 // Delay this mem node transformation until the address is processed.
277 phase->is_IterGVN()->_worklist.push(this);
278 return NodeSentinel; // caller will return NULL
279 }
281 // Do NOT remove or optimize the next lines: ensure a new alias index
282 // is allocated for an oop pointer type before Escape Analysis.
283 // Note: C++ will not remove it since the call has side effect.
284 if ( t_adr->isa_oopptr() ) {
285 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
286 }
288 #ifdef ASSERT
289 Node* base = NULL;
290 if (address->is_AddP())
291 base = address->in(AddPNode::Base);
292 assert(base == NULL || t_adr->isa_rawptr() ||
293 !phase->type(base)->higher_equal(TypePtr::NULL_PTR), "NULL+offs not RAW address?");
294 #endif
296 // Avoid independent memory operations
297 Node* old_mem = mem;
299 // The code which unhooks non-raw memories from complete (macro-expanded)
300 // initializations was removed. After macro-expansion all stores catched
301 // by Initialize node became raw stores and there is no information
302 // which memory slices they modify. So it is unsafe to move any memory
303 // operation above these stores. Also in most cases hooked non-raw memories
304 // were already unhooked by using information from detect_ptr_independence()
305 // and find_previous_store().
307 if (mem->is_MergeMem()) {
308 MergeMemNode* mmem = mem->as_MergeMem();
309 const TypePtr *tp = t_adr->is_ptr();
311 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
312 }
314 if (mem != old_mem) {
315 set_req(MemNode::Memory, mem);
316 if (phase->type( mem ) == Type::TOP) return NodeSentinel;
317 return this;
318 }
320 // let the subclass continue analyzing...
321 return NULL;
322 }
324 // Helper function for proving some simple control dominations.
325 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
326 // Already assumes that 'dom' is available at 'sub', and that 'sub'
327 // is not a constant (dominated by the method's StartNode).
328 // Used by MemNode::find_previous_store to prove that the
329 // control input of a memory operation predates (dominates)
330 // an allocation it wants to look past.
331 bool MemNode::all_controls_dominate(Node* dom, Node* sub) {
332 if (dom == NULL || dom->is_top() || sub == NULL || sub->is_top())
333 return false; // Conservative answer for dead code
335 // Check 'dom'. Skip Proj and CatchProj nodes.
336 dom = dom->find_exact_control(dom);
337 if (dom == NULL || dom->is_top())
338 return false; // Conservative answer for dead code
340 if (dom == sub) {
341 // For the case when, for example, 'sub' is Initialize and the original
342 // 'dom' is Proj node of the 'sub'.
343 return false;
344 }
346 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub)
347 return true;
349 // 'dom' dominates 'sub' if its control edge and control edges
350 // of all its inputs dominate or equal to sub's control edge.
352 // Currently 'sub' is either Allocate, Initialize or Start nodes.
353 // Or Region for the check in LoadNode::Ideal();
354 // 'sub' should have sub->in(0) != NULL.
355 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
356 sub->is_Region(), "expecting only these nodes");
358 // Get control edge of 'sub'.
359 Node* orig_sub = sub;
360 sub = sub->find_exact_control(sub->in(0));
361 if (sub == NULL || sub->is_top())
362 return false; // Conservative answer for dead code
364 assert(sub->is_CFG(), "expecting control");
366 if (sub == dom)
367 return true;
369 if (sub->is_Start() || sub->is_Root())
370 return false;
372 {
373 // Check all control edges of 'dom'.
375 ResourceMark rm;
376 Arena* arena = Thread::current()->resource_area();
377 Node_List nlist(arena);
378 Unique_Node_List dom_list(arena);
380 dom_list.push(dom);
381 bool only_dominating_controls = false;
383 for (uint next = 0; next < dom_list.size(); next++) {
384 Node* n = dom_list.at(next);
385 if (n == orig_sub)
386 return false; // One of dom's inputs dominated by sub.
387 if (!n->is_CFG() && n->pinned()) {
388 // Check only own control edge for pinned non-control nodes.
389 n = n->find_exact_control(n->in(0));
390 if (n == NULL || n->is_top())
391 return false; // Conservative answer for dead code
392 assert(n->is_CFG(), "expecting control");
393 dom_list.push(n);
394 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
395 only_dominating_controls = true;
396 } else if (n->is_CFG()) {
397 if (n->dominates(sub, nlist))
398 only_dominating_controls = true;
399 else
400 return false;
401 } else {
402 // First, own control edge.
403 Node* m = n->find_exact_control(n->in(0));
404 if (m != NULL) {
405 if (m->is_top())
406 return false; // Conservative answer for dead code
407 dom_list.push(m);
408 }
409 // Now, the rest of edges.
410 uint cnt = n->req();
411 for (uint i = 1; i < cnt; i++) {
412 m = n->find_exact_control(n->in(i));
413 if (m == NULL || m->is_top())
414 continue;
415 dom_list.push(m);
416 }
417 }
418 }
419 return only_dominating_controls;
420 }
421 }
423 //---------------------detect_ptr_independence---------------------------------
424 // Used by MemNode::find_previous_store to prove that two base
425 // pointers are never equal.
426 // The pointers are accompanied by their associated allocations,
427 // if any, which have been previously discovered by the caller.
428 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
429 Node* p2, AllocateNode* a2,
430 PhaseTransform* phase) {
431 // Attempt to prove that these two pointers cannot be aliased.
432 // They may both manifestly be allocations, and they should differ.
433 // Or, if they are not both allocations, they can be distinct constants.
434 // Otherwise, one is an allocation and the other a pre-existing value.
435 if (a1 == NULL && a2 == NULL) { // neither an allocation
436 return (p1 != p2) && p1->is_Con() && p2->is_Con();
437 } else if (a1 != NULL && a2 != NULL) { // both allocations
438 return (a1 != a2);
439 } else if (a1 != NULL) { // one allocation a1
440 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
441 return all_controls_dominate(p2, a1);
442 } else { //(a2 != NULL) // one allocation a2
443 return all_controls_dominate(p1, a2);
444 }
445 return false;
446 }
449 // The logic for reordering loads and stores uses four steps:
450 // (a) Walk carefully past stores and initializations which we
451 // can prove are independent of this load.
452 // (b) Observe that the next memory state makes an exact match
453 // with self (load or store), and locate the relevant store.
454 // (c) Ensure that, if we were to wire self directly to the store,
455 // the optimizer would fold it up somehow.
456 // (d) Do the rewiring, and return, depending on some other part of
457 // the optimizer to fold up the load.
458 // This routine handles steps (a) and (b). Steps (c) and (d) are
459 // specific to loads and stores, so they are handled by the callers.
460 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
461 //
462 Node* MemNode::find_previous_store(PhaseTransform* phase) {
463 Node* ctrl = in(MemNode::Control);
464 Node* adr = in(MemNode::Address);
465 intptr_t offset = 0;
466 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
467 AllocateNode* alloc = AllocateNode::Ideal_allocation(base, phase);
469 if (offset == Type::OffsetBot)
470 return NULL; // cannot unalias unless there are precise offsets
472 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
474 intptr_t size_in_bytes = memory_size();
476 Node* mem = in(MemNode::Memory); // start searching here...
478 int cnt = 50; // Cycle limiter
479 for (;;) { // While we can dance past unrelated stores...
480 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
482 if (mem->is_Store()) {
483 Node* st_adr = mem->in(MemNode::Address);
484 intptr_t st_offset = 0;
485 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
486 if (st_base == NULL)
487 break; // inscrutable pointer
488 if (st_offset != offset && st_offset != Type::OffsetBot) {
489 const int MAX_STORE = BytesPerLong;
490 if (st_offset >= offset + size_in_bytes ||
491 st_offset <= offset - MAX_STORE ||
492 st_offset <= offset - mem->as_Store()->memory_size()) {
493 // Success: The offsets are provably independent.
494 // (You may ask, why not just test st_offset != offset and be done?
495 // The answer is that stores of different sizes can co-exist
496 // in the same sequence of RawMem effects. We sometimes initialize
497 // a whole 'tile' of array elements with a single jint or jlong.)
498 mem = mem->in(MemNode::Memory);
499 continue; // (a) advance through independent store memory
500 }
501 }
502 if (st_base != base &&
503 detect_ptr_independence(base, alloc,
504 st_base,
505 AllocateNode::Ideal_allocation(st_base, phase),
506 phase)) {
507 // Success: The bases are provably independent.
508 mem = mem->in(MemNode::Memory);
509 continue; // (a) advance through independent store memory
510 }
512 // (b) At this point, if the bases or offsets do not agree, we lose,
513 // since we have not managed to prove 'this' and 'mem' independent.
514 if (st_base == base && st_offset == offset) {
515 return mem; // let caller handle steps (c), (d)
516 }
518 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
519 InitializeNode* st_init = mem->in(0)->as_Initialize();
520 AllocateNode* st_alloc = st_init->allocation();
521 if (st_alloc == NULL)
522 break; // something degenerated
523 bool known_identical = false;
524 bool known_independent = false;
525 if (alloc == st_alloc)
526 known_identical = true;
527 else if (alloc != NULL)
528 known_independent = true;
529 else if (all_controls_dominate(this, st_alloc))
530 known_independent = true;
532 if (known_independent) {
533 // The bases are provably independent: Either they are
534 // manifestly distinct allocations, or else the control
535 // of this load dominates the store's allocation.
536 int alias_idx = phase->C->get_alias_index(adr_type());
537 if (alias_idx == Compile::AliasIdxRaw) {
538 mem = st_alloc->in(TypeFunc::Memory);
539 } else {
540 mem = st_init->memory(alias_idx);
541 }
542 continue; // (a) advance through independent store memory
543 }
545 // (b) at this point, if we are not looking at a store initializing
546 // the same allocation we are loading from, we lose.
547 if (known_identical) {
548 // From caller, can_see_stored_value will consult find_captured_store.
549 return mem; // let caller handle steps (c), (d)
550 }
552 } else if (addr_t != NULL && addr_t->is_known_instance_field()) {
553 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
554 if (mem->is_Proj() && mem->in(0)->is_Call()) {
555 CallNode *call = mem->in(0)->as_Call();
556 if (!call->may_modify(addr_t, phase)) {
557 mem = call->in(TypeFunc::Memory);
558 continue; // (a) advance through independent call memory
559 }
560 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
561 mem = mem->in(0)->in(TypeFunc::Memory);
562 continue; // (a) advance through independent MemBar memory
563 } else if (mem->is_ClearArray()) {
564 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
565 // (the call updated 'mem' value)
566 continue; // (a) advance through independent allocation memory
567 } else {
568 // Can not bypass initialization of the instance
569 // we are looking for.
570 return mem;
571 }
572 } else if (mem->is_MergeMem()) {
573 int alias_idx = phase->C->get_alias_index(adr_type());
574 mem = mem->as_MergeMem()->memory_at(alias_idx);
575 continue; // (a) advance through independent MergeMem memory
576 }
577 }
579 // Unless there is an explicit 'continue', we must bail out here,
580 // because 'mem' is an inscrutable memory state (e.g., a call).
581 break;
582 }
584 return NULL; // bail out
585 }
587 //----------------------calculate_adr_type-------------------------------------
588 // Helper function. Notices when the given type of address hits top or bottom.
589 // Also, asserts a cross-check of the type against the expected address type.
590 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
591 if (t == Type::TOP) return NULL; // does not touch memory any more?
592 #ifdef PRODUCT
593 cross_check = NULL;
594 #else
595 if (!VerifyAliases || is_error_reported() || Node::in_dump()) cross_check = NULL;
596 #endif
597 const TypePtr* tp = t->isa_ptr();
598 if (tp == NULL) {
599 assert(cross_check == NULL || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
600 return TypePtr::BOTTOM; // touches lots of memory
601 } else {
602 #ifdef ASSERT
603 // %%%% [phh] We don't check the alias index if cross_check is
604 // TypeRawPtr::BOTTOM. Needs to be investigated.
605 if (cross_check != NULL &&
606 cross_check != TypePtr::BOTTOM &&
607 cross_check != TypeRawPtr::BOTTOM) {
608 // Recheck the alias index, to see if it has changed (due to a bug).
609 Compile* C = Compile::current();
610 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
611 "must stay in the original alias category");
612 // The type of the address must be contained in the adr_type,
613 // disregarding "null"-ness.
614 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
615 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
616 assert(cross_check->meet(tp_notnull) == cross_check,
617 "real address must not escape from expected memory type");
618 }
619 #endif
620 return tp;
621 }
622 }
624 //------------------------adr_phi_is_loop_invariant----------------------------
625 // A helper function for Ideal_DU_postCCP to check if a Phi in a counted
626 // loop is loop invariant. Make a quick traversal of Phi and associated
627 // CastPP nodes, looking to see if they are a closed group within the loop.
628 bool MemNode::adr_phi_is_loop_invariant(Node* adr_phi, Node* cast) {
629 // The idea is that the phi-nest must boil down to only CastPP nodes
630 // with the same data. This implies that any path into the loop already
631 // includes such a CastPP, and so the original cast, whatever its input,
632 // must be covered by an equivalent cast, with an earlier control input.
633 ResourceMark rm;
635 // The loop entry input of the phi should be the unique dominating
636 // node for every Phi/CastPP in the loop.
637 Unique_Node_List closure;
638 closure.push(adr_phi->in(LoopNode::EntryControl));
640 // Add the phi node and the cast to the worklist.
641 Unique_Node_List worklist;
642 worklist.push(adr_phi);
643 if( cast != NULL ){
644 if( !cast->is_ConstraintCast() ) return false;
645 worklist.push(cast);
646 }
648 // Begin recursive walk of phi nodes.
649 while( worklist.size() ){
650 // Take a node off the worklist
651 Node *n = worklist.pop();
652 if( !closure.member(n) ){
653 // Add it to the closure.
654 closure.push(n);
655 // Make a sanity check to ensure we don't waste too much time here.
656 if( closure.size() > 20) return false;
657 // This node is OK if:
658 // - it is a cast of an identical value
659 // - or it is a phi node (then we add its inputs to the worklist)
660 // Otherwise, the node is not OK, and we presume the cast is not invariant
661 if( n->is_ConstraintCast() ){
662 worklist.push(n->in(1));
663 } else if( n->is_Phi() ) {
664 for( uint i = 1; i < n->req(); i++ ) {
665 worklist.push(n->in(i));
666 }
667 } else {
668 return false;
669 }
670 }
671 }
673 // Quit when the worklist is empty, and we've found no offending nodes.
674 return true;
675 }
677 //------------------------------Ideal_DU_postCCP-------------------------------
678 // Find any cast-away of null-ness and keep its control. Null cast-aways are
679 // going away in this pass and we need to make this memory op depend on the
680 // gating null check.
681 Node *MemNode::Ideal_DU_postCCP( PhaseCCP *ccp ) {
682 return Ideal_common_DU_postCCP(ccp, this, in(MemNode::Address));
683 }
685 // I tried to leave the CastPP's in. This makes the graph more accurate in
686 // some sense; we get to keep around the knowledge that an oop is not-null
687 // after some test. Alas, the CastPP's interfere with GVN (some values are
688 // the regular oop, some are the CastPP of the oop, all merge at Phi's which
689 // cannot collapse, etc). This cost us 10% on SpecJVM, even when I removed
690 // some of the more trivial cases in the optimizer. Removing more useless
691 // Phi's started allowing Loads to illegally float above null checks. I gave
692 // up on this approach. CNC 10/20/2000
693 // This static method may be called not from MemNode (EncodePNode calls it).
694 // Only the control edge of the node 'n' might be updated.
695 Node *MemNode::Ideal_common_DU_postCCP( PhaseCCP *ccp, Node* n, Node* adr ) {
696 Node *skipped_cast = NULL;
697 // Need a null check? Regular static accesses do not because they are
698 // from constant addresses. Array ops are gated by the range check (which
699 // always includes a NULL check). Just check field ops.
700 if( n->in(MemNode::Control) == NULL ) {
701 // Scan upwards for the highest location we can place this memory op.
702 while( true ) {
703 switch( adr->Opcode() ) {
705 case Op_AddP: // No change to NULL-ness, so peek thru AddP's
706 adr = adr->in(AddPNode::Base);
707 continue;
709 case Op_DecodeN: // No change to NULL-ness, so peek thru
710 adr = adr->in(1);
711 continue;
713 case Op_CastPP:
714 // If the CastPP is useless, just peek on through it.
715 if( ccp->type(adr) == ccp->type(adr->in(1)) ) {
716 // Remember the cast that we've peeked though. If we peek
717 // through more than one, then we end up remembering the highest
718 // one, that is, if in a loop, the one closest to the top.
719 skipped_cast = adr;
720 adr = adr->in(1);
721 continue;
722 }
723 // CastPP is going away in this pass! We need this memory op to be
724 // control-dependent on the test that is guarding the CastPP.
725 ccp->hash_delete(n);
726 n->set_req(MemNode::Control, adr->in(0));
727 ccp->hash_insert(n);
728 return n;
730 case Op_Phi:
731 // Attempt to float above a Phi to some dominating point.
732 if (adr->in(0) != NULL && adr->in(0)->is_CountedLoop()) {
733 // If we've already peeked through a Cast (which could have set the
734 // control), we can't float above a Phi, because the skipped Cast
735 // may not be loop invariant.
736 if (adr_phi_is_loop_invariant(adr, skipped_cast)) {
737 adr = adr->in(1);
738 continue;
739 }
740 }
742 // Intentional fallthrough!
744 // No obvious dominating point. The mem op is pinned below the Phi
745 // by the Phi itself. If the Phi goes away (no true value is merged)
746 // then the mem op can float, but not indefinitely. It must be pinned
747 // behind the controls leading to the Phi.
748 case Op_CheckCastPP:
749 // These usually stick around to change address type, however a
750 // useless one can be elided and we still need to pick up a control edge
751 if (adr->in(0) == NULL) {
752 // This CheckCastPP node has NO control and is likely useless. But we
753 // need check further up the ancestor chain for a control input to keep
754 // the node in place. 4959717.
755 skipped_cast = adr;
756 adr = adr->in(1);
757 continue;
758 }
759 ccp->hash_delete(n);
760 n->set_req(MemNode::Control, adr->in(0));
761 ccp->hash_insert(n);
762 return n;
764 // List of "safe" opcodes; those that implicitly block the memory
765 // op below any null check.
766 case Op_CastX2P: // no null checks on native pointers
767 case Op_Parm: // 'this' pointer is not null
768 case Op_LoadP: // Loading from within a klass
769 case Op_LoadN: // Loading from within a klass
770 case Op_LoadKlass: // Loading from within a klass
771 case Op_LoadNKlass: // Loading from within a klass
772 case Op_ConP: // Loading from a klass
773 case Op_ConN: // Loading from a klass
774 case Op_CreateEx: // Sucking up the guts of an exception oop
775 case Op_Con: // Reading from TLS
776 case Op_CMoveP: // CMoveP is pinned
777 case Op_CMoveN: // CMoveN is pinned
778 break; // No progress
780 case Op_Proj: // Direct call to an allocation routine
781 case Op_SCMemProj: // Memory state from store conditional ops
782 #ifdef ASSERT
783 {
784 assert(adr->as_Proj()->_con == TypeFunc::Parms, "must be return value");
785 const Node* call = adr->in(0);
786 if (call->is_CallJava()) {
787 const CallJavaNode* call_java = call->as_CallJava();
788 const TypeTuple *r = call_java->tf()->range();
789 assert(r->cnt() > TypeFunc::Parms, "must return value");
790 const Type* ret_type = r->field_at(TypeFunc::Parms);
791 assert(ret_type && ret_type->isa_ptr(), "must return pointer");
792 // We further presume that this is one of
793 // new_instance_Java, new_array_Java, or
794 // the like, but do not assert for this.
795 } else if (call->is_Allocate()) {
796 // similar case to new_instance_Java, etc.
797 } else if (!call->is_CallLeaf()) {
798 // Projections from fetch_oop (OSR) are allowed as well.
799 ShouldNotReachHere();
800 }
801 }
802 #endif
803 break;
804 default:
805 ShouldNotReachHere();
806 }
807 break;
808 }
809 }
811 return NULL; // No progress
812 }
815 //=============================================================================
816 uint LoadNode::size_of() const { return sizeof(*this); }
817 uint LoadNode::cmp( const Node &n ) const
818 { return !Type::cmp( _type, ((LoadNode&)n)._type ); }
819 const Type *LoadNode::bottom_type() const { return _type; }
820 uint LoadNode::ideal_reg() const {
821 return Matcher::base2reg[_type->base()];
822 }
824 #ifndef PRODUCT
825 void LoadNode::dump_spec(outputStream *st) const {
826 MemNode::dump_spec(st);
827 if( !Verbose && !WizardMode ) {
828 // standard dump does this in Verbose and WizardMode
829 st->print(" #"); _type->dump_on(st);
830 }
831 }
832 #endif
834 #ifdef ASSERT
835 //----------------------------is_immutable_value-------------------------------
836 // Helper function to allow a raw load without control edge for some cases
837 bool LoadNode::is_immutable_value(Node* adr) {
838 return (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
839 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
840 (adr->in(AddPNode::Offset)->find_intptr_t_con(-1) ==
841 in_bytes(JavaThread::osthread_offset())));
842 }
843 #endif
845 //----------------------------LoadNode::make-----------------------------------
846 // Polymorphic factory method:
847 Node *LoadNode::make( PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt ) {
848 Compile* C = gvn.C;
850 // sanity check the alias category against the created node type
851 assert(!(adr_type->isa_oopptr() &&
852 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
853 "use LoadKlassNode instead");
854 assert(!(adr_type->isa_aryptr() &&
855 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
856 "use LoadRangeNode instead");
857 // Check control edge of raw loads
858 assert( ctl != NULL || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
859 // oop will be recorded in oop map if load crosses safepoint
860 rt->isa_oopptr() || is_immutable_value(adr),
861 "raw memory operations should have control edge");
862 switch (bt) {
863 case T_BOOLEAN: return new (C, 3) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int() );
864 case T_BYTE: return new (C, 3) LoadBNode (ctl, mem, adr, adr_type, rt->is_int() );
865 case T_INT: return new (C, 3) LoadINode (ctl, mem, adr, adr_type, rt->is_int() );
866 case T_CHAR: return new (C, 3) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int() );
867 case T_SHORT: return new (C, 3) LoadSNode (ctl, mem, adr, adr_type, rt->is_int() );
868 case T_LONG: return new (C, 3) LoadLNode (ctl, mem, adr, adr_type, rt->is_long() );
869 case T_FLOAT: return new (C, 3) LoadFNode (ctl, mem, adr, adr_type, rt );
870 case T_DOUBLE: return new (C, 3) LoadDNode (ctl, mem, adr, adr_type, rt );
871 case T_ADDRESS: return new (C, 3) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr() );
872 case T_OBJECT:
873 #ifdef _LP64
874 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
875 Node* load = gvn.transform(new (C, 3) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop()));
876 return new (C, 2) DecodeNNode(load, load->bottom_type()->make_ptr());
877 } else
878 #endif
879 {
880 assert(!adr->bottom_type()->is_ptr_to_narrowoop(), "should have got back a narrow oop");
881 return new (C, 3) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr());
882 }
883 }
884 ShouldNotReachHere();
885 return (LoadNode*)NULL;
886 }
888 LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt) {
889 bool require_atomic = true;
890 return new (C, 3) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), require_atomic);
891 }
896 //------------------------------hash-------------------------------------------
897 uint LoadNode::hash() const {
898 // unroll addition of interesting fields
899 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
900 }
902 //---------------------------can_see_stored_value------------------------------
903 // This routine exists to make sure this set of tests is done the same
904 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
905 // will change the graph shape in a way which makes memory alive twice at the
906 // same time (uses the Oracle model of aliasing), then some
907 // LoadXNode::Identity will fold things back to the equivalence-class model
908 // of aliasing.
909 Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
910 Node* ld_adr = in(MemNode::Address);
912 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
913 Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
914 if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
915 atp->field() != NULL && !atp->field()->is_volatile()) {
916 uint alias_idx = atp->index();
917 bool final = atp->field()->is_final();
918 Node* result = NULL;
919 Node* current = st;
920 // Skip through chains of MemBarNodes checking the MergeMems for
921 // new states for the slice of this load. Stop once any other
922 // kind of node is encountered. Loads from final memory can skip
923 // through any kind of MemBar but normal loads shouldn't skip
924 // through MemBarAcquire since the could allow them to move out of
925 // a synchronized region.
926 while (current->is_Proj()) {
927 int opc = current->in(0)->Opcode();
928 if ((final && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock)) ||
929 opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder ||
930 opc == Op_MemBarReleaseLock) {
931 Node* mem = current->in(0)->in(TypeFunc::Memory);
932 if (mem->is_MergeMem()) {
933 MergeMemNode* merge = mem->as_MergeMem();
934 Node* new_st = merge->memory_at(alias_idx);
935 if (new_st == merge->base_memory()) {
936 // Keep searching
937 current = merge->base_memory();
938 continue;
939 }
940 // Save the new memory state for the slice and fall through
941 // to exit.
942 result = new_st;
943 }
944 }
945 break;
946 }
947 if (result != NULL) {
948 st = result;
949 }
950 }
953 // Loop around twice in the case Load -> Initialize -> Store.
954 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
955 for (int trip = 0; trip <= 1; trip++) {
957 if (st->is_Store()) {
958 Node* st_adr = st->in(MemNode::Address);
959 if (!phase->eqv(st_adr, ld_adr)) {
960 // Try harder before giving up... Match raw and non-raw pointers.
961 intptr_t st_off = 0;
962 AllocateNode* alloc = AllocateNode::Ideal_allocation(st_adr, phase, st_off);
963 if (alloc == NULL) return NULL;
964 intptr_t ld_off = 0;
965 AllocateNode* allo2 = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
966 if (alloc != allo2) return NULL;
967 if (ld_off != st_off) return NULL;
968 // At this point we have proven something like this setup:
969 // A = Allocate(...)
970 // L = LoadQ(, AddP(CastPP(, A.Parm),, #Off))
971 // S = StoreQ(, AddP(, A.Parm , #Off), V)
972 // (Actually, we haven't yet proven the Q's are the same.)
973 // In other words, we are loading from a casted version of
974 // the same pointer-and-offset that we stored to.
975 // Thus, we are able to replace L by V.
976 }
977 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
978 if (store_Opcode() != st->Opcode())
979 return NULL;
980 return st->in(MemNode::ValueIn);
981 }
983 intptr_t offset = 0; // scratch
985 // A load from a freshly-created object always returns zero.
986 // (This can happen after LoadNode::Ideal resets the load's memory input
987 // to find_captured_store, which returned InitializeNode::zero_memory.)
988 if (st->is_Proj() && st->in(0)->is_Allocate() &&
989 st->in(0) == AllocateNode::Ideal_allocation(ld_adr, phase, offset) &&
990 offset >= st->in(0)->as_Allocate()->minimum_header_size()) {
991 // return a zero value for the load's basic type
992 // (This is one of the few places where a generic PhaseTransform
993 // can create new nodes. Think of it as lazily manifesting
994 // virtually pre-existing constants.)
995 return phase->zerocon(memory_type());
996 }
998 // A load from an initialization barrier can match a captured store.
999 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1000 InitializeNode* init = st->in(0)->as_Initialize();
1001 AllocateNode* alloc = init->allocation();
1002 if (alloc != NULL &&
1003 alloc == AllocateNode::Ideal_allocation(ld_adr, phase, offset)) {
1004 // examine a captured store value
1005 st = init->find_captured_store(offset, memory_size(), phase);
1006 if (st != NULL)
1007 continue; // take one more trip around
1008 }
1009 }
1011 break;
1012 }
1014 return NULL;
1015 }
1017 //----------------------is_instance_field_load_with_local_phi------------------
1018 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1019 if( in(MemNode::Memory)->is_Phi() && in(MemNode::Memory)->in(0) == ctrl &&
1020 in(MemNode::Address)->is_AddP() ) {
1021 const TypeOopPtr* t_oop = in(MemNode::Address)->bottom_type()->isa_oopptr();
1022 // Only instances.
1023 if( t_oop != NULL && t_oop->is_known_instance_field() &&
1024 t_oop->offset() != Type::OffsetBot &&
1025 t_oop->offset() != Type::OffsetTop) {
1026 return true;
1027 }
1028 }
1029 return false;
1030 }
1032 //------------------------------Identity---------------------------------------
1033 // Loads are identity if previous store is to same address
1034 Node *LoadNode::Identity( PhaseTransform *phase ) {
1035 // If the previous store-maker is the right kind of Store, and the store is
1036 // to the same address, then we are equal to the value stored.
1037 Node* mem = in(MemNode::Memory);
1038 Node* value = can_see_stored_value(mem, phase);
1039 if( value ) {
1040 // byte, short & char stores truncate naturally.
1041 // A load has to load the truncated value which requires
1042 // some sort of masking operation and that requires an
1043 // Ideal call instead of an Identity call.
1044 if (memory_size() < BytesPerInt) {
1045 // If the input to the store does not fit with the load's result type,
1046 // it must be truncated via an Ideal call.
1047 if (!phase->type(value)->higher_equal(phase->type(this)))
1048 return this;
1049 }
1050 // (This works even when value is a Con, but LoadNode::Value
1051 // usually runs first, producing the singleton type of the Con.)
1052 return value;
1053 }
1055 // Search for an existing data phi which was generated before for the same
1056 // instance's field to avoid infinite generation of phis in a loop.
1057 Node *region = mem->in(0);
1058 if (is_instance_field_load_with_local_phi(region)) {
1059 const TypePtr *addr_t = in(MemNode::Address)->bottom_type()->isa_ptr();
1060 int this_index = phase->C->get_alias_index(addr_t);
1061 int this_offset = addr_t->offset();
1062 int this_id = addr_t->is_oopptr()->instance_id();
1063 const Type* this_type = bottom_type();
1064 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1065 Node* phi = region->fast_out(i);
1066 if (phi->is_Phi() && phi != mem &&
1067 phi->as_Phi()->is_same_inst_field(this_type, this_id, this_index, this_offset)) {
1068 return phi;
1069 }
1070 }
1071 }
1073 return this;
1074 }
1077 // Returns true if the AliasType refers to the field that holds the
1078 // cached box array. Currently only handles the IntegerCache case.
1079 static bool is_autobox_cache(Compile::AliasType* atp) {
1080 if (atp != NULL && atp->field() != NULL) {
1081 ciField* field = atp->field();
1082 ciSymbol* klass = field->holder()->name();
1083 if (field->name() == ciSymbol::cache_field_name() &&
1084 field->holder()->uses_default_loader() &&
1085 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1086 return true;
1087 }
1088 }
1089 return false;
1090 }
1092 // Fetch the base value in the autobox array
1093 static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
1094 if (atp != NULL && atp->field() != NULL) {
1095 ciField* field = atp->field();
1096 ciSymbol* klass = field->holder()->name();
1097 if (field->name() == ciSymbol::cache_field_name() &&
1098 field->holder()->uses_default_loader() &&
1099 klass == ciSymbol::java_lang_Integer_IntegerCache()) {
1100 assert(field->is_constant(), "what?");
1101 ciObjArray* array = field->constant_value().as_object()->as_obj_array();
1102 // Fetch the box object at the base of the array and get its value
1103 ciInstance* box = array->obj_at(0)->as_instance();
1104 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1105 if (ik->nof_nonstatic_fields() == 1) {
1106 // This should be true nonstatic_field_at requires calling
1107 // nof_nonstatic_fields so check it anyway
1108 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1109 cache_offset = c.as_int();
1110 }
1111 return true;
1112 }
1113 }
1114 return false;
1115 }
1117 // Returns true if the AliasType refers to the value field of an
1118 // autobox object. Currently only handles Integer.
1119 static bool is_autobox_object(Compile::AliasType* atp) {
1120 if (atp != NULL && atp->field() != NULL) {
1121 ciField* field = atp->field();
1122 ciSymbol* klass = field->holder()->name();
1123 if (field->name() == ciSymbol::value_name() &&
1124 field->holder()->uses_default_loader() &&
1125 klass == ciSymbol::java_lang_Integer()) {
1126 return true;
1127 }
1128 }
1129 return false;
1130 }
1133 // We're loading from an object which has autobox behaviour.
1134 // If this object is result of a valueOf call we'll have a phi
1135 // merging a newly allocated object and a load from the cache.
1136 // We want to replace this load with the original incoming
1137 // argument to the valueOf call.
1138 Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
1139 Node* base = in(Address)->in(AddPNode::Base);
1140 if (base->is_Phi() && base->req() == 3) {
1141 AllocateNode* allocation = NULL;
1142 int allocation_index = -1;
1143 int load_index = -1;
1144 for (uint i = 1; i < base->req(); i++) {
1145 allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
1146 if (allocation != NULL) {
1147 allocation_index = i;
1148 load_index = 3 - allocation_index;
1149 break;
1150 }
1151 }
1152 bool has_load = ( allocation != NULL &&
1153 (base->in(load_index)->is_Load() ||
1154 base->in(load_index)->is_DecodeN() &&
1155 base->in(load_index)->in(1)->is_Load()) );
1156 if (has_load && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
1157 // Push the loads from the phi that comes from valueOf up
1158 // through it to allow elimination of the loads and the recovery
1159 // of the original value.
1160 Node* mem_phi = in(Memory);
1161 Node* offset = in(Address)->in(AddPNode::Offset);
1162 Node* region = base->in(0);
1164 Node* in1 = clone();
1165 Node* in1_addr = in1->in(Address)->clone();
1166 in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
1167 in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
1168 in1_addr->set_req(AddPNode::Offset, offset);
1169 in1->set_req(0, region->in(allocation_index));
1170 in1->set_req(Address, in1_addr);
1171 in1->set_req(Memory, mem_phi->in(allocation_index));
1173 Node* in2 = clone();
1174 Node* in2_addr = in2->in(Address)->clone();
1175 in2_addr->set_req(AddPNode::Base, base->in(load_index));
1176 in2_addr->set_req(AddPNode::Address, base->in(load_index));
1177 in2_addr->set_req(AddPNode::Offset, offset);
1178 in2->set_req(0, region->in(load_index));
1179 in2->set_req(Address, in2_addr);
1180 in2->set_req(Memory, mem_phi->in(load_index));
1182 in1_addr = phase->transform(in1_addr);
1183 in1 = phase->transform(in1);
1184 in2_addr = phase->transform(in2_addr);
1185 in2 = phase->transform(in2);
1187 PhiNode* result = PhiNode::make_blank(region, this);
1188 result->set_req(allocation_index, in1);
1189 result->set_req(load_index, in2);
1190 return result;
1191 }
1192 } else if (base->is_Load() ||
1193 base->is_DecodeN() && base->in(1)->is_Load()) {
1194 if (base->is_DecodeN()) {
1195 // Get LoadN node which loads cached Integer object
1196 base = base->in(1);
1197 }
1198 // Eliminate the load of Integer.value for integers from the cache
1199 // array by deriving the value from the index into the array.
1200 // Capture the offset of the load and then reverse the computation.
1201 Node* load_base = base->in(Address)->in(AddPNode::Base);
1202 if (load_base->is_DecodeN()) {
1203 // Get LoadN node which loads IntegerCache.cache field
1204 load_base = load_base->in(1);
1205 }
1206 if (load_base != NULL) {
1207 Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
1208 intptr_t cache_offset;
1209 int shift = -1;
1210 Node* cache = NULL;
1211 if (is_autobox_cache(atp)) {
1212 shift = exact_log2(type2aelembytes(T_OBJECT));
1213 cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
1214 }
1215 if (cache != NULL && base->in(Address)->is_AddP()) {
1216 Node* elements[4];
1217 int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
1218 int cache_low;
1219 if (count > 0 && fetch_autobox_base(atp, cache_low)) {
1220 int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
1221 // Add up all the offsets making of the address of the load
1222 Node* result = elements[0];
1223 for (int i = 1; i < count; i++) {
1224 result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
1225 }
1226 // Remove the constant offset from the address and then
1227 // remove the scaling of the offset to recover the original index.
1228 result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
1229 if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
1230 // Peel the shift off directly but wrap it in a dummy node
1231 // since Ideal can't return existing nodes
1232 result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
1233 } else {
1234 result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
1235 }
1236 #ifdef _LP64
1237 result = new (phase->C, 2) ConvL2INode(phase->transform(result));
1238 #endif
1239 return result;
1240 }
1241 }
1242 }
1243 }
1244 return NULL;
1245 }
1247 //------------------------------split_through_phi------------------------------
1248 // Split instance field load through Phi.
1249 Node *LoadNode::split_through_phi(PhaseGVN *phase) {
1250 Node* mem = in(MemNode::Memory);
1251 Node* address = in(MemNode::Address);
1252 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1253 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1255 assert(mem->is_Phi() && (t_oop != NULL) &&
1256 t_oop->is_known_instance_field(), "invalide conditions");
1258 Node *region = mem->in(0);
1259 if (region == NULL) {
1260 return NULL; // Wait stable graph
1261 }
1262 uint cnt = mem->req();
1263 for (uint i = 1; i < cnt; i++) {
1264 Node* rc = region->in(i);
1265 if (rc == NULL || phase->type(rc) == Type::TOP)
1266 return NULL; // Wait stable graph
1267 Node *in = mem->in(i);
1268 if (in == NULL) {
1269 return NULL; // Wait stable graph
1270 }
1271 }
1272 // Check for loop invariant.
1273 if (cnt == 3) {
1274 for (uint i = 1; i < cnt; i++) {
1275 Node *in = mem->in(i);
1276 Node* m = MemNode::optimize_memory_chain(in, addr_t, phase);
1277 if (m == mem) {
1278 set_req(MemNode::Memory, mem->in(cnt - i)); // Skip this phi.
1279 return this;
1280 }
1281 }
1282 }
1283 // Split through Phi (see original code in loopopts.cpp).
1284 assert(phase->C->have_alias_type(addr_t), "instance should have alias type");
1286 // Do nothing here if Identity will find a value
1287 // (to avoid infinite chain of value phis generation).
1288 if (!phase->eqv(this, this->Identity(phase)))
1289 return NULL;
1291 // Skip the split if the region dominates some control edge of the address.
1292 if (!MemNode::all_controls_dominate(address, region))
1293 return NULL;
1295 const Type* this_type = this->bottom_type();
1296 int this_index = phase->C->get_alias_index(addr_t);
1297 int this_offset = addr_t->offset();
1298 int this_iid = addr_t->is_oopptr()->instance_id();
1299 PhaseIterGVN *igvn = phase->is_IterGVN();
1300 Node *phi = new (igvn->C, region->req()) PhiNode(region, this_type, NULL, this_iid, this_index, this_offset);
1301 for (uint i = 1; i < region->req(); i++) {
1302 Node *x;
1303 Node* the_clone = NULL;
1304 if (region->in(i) == phase->C->top()) {
1305 x = phase->C->top(); // Dead path? Use a dead data op
1306 } else {
1307 x = this->clone(); // Else clone up the data op
1308 the_clone = x; // Remember for possible deletion.
1309 // Alter data node to use pre-phi inputs
1310 if (this->in(0) == region) {
1311 x->set_req(0, region->in(i));
1312 } else {
1313 x->set_req(0, NULL);
1314 }
1315 for (uint j = 1; j < this->req(); j++) {
1316 Node *in = this->in(j);
1317 if (in->is_Phi() && in->in(0) == region)
1318 x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
1319 }
1320 }
1321 // Check for a 'win' on some paths
1322 const Type *t = x->Value(igvn);
1324 bool singleton = t->singleton();
1326 // See comments in PhaseIdealLoop::split_thru_phi().
1327 if (singleton && t == Type::TOP) {
1328 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1329 }
1331 if (singleton) {
1332 x = igvn->makecon(t);
1333 } else {
1334 // We now call Identity to try to simplify the cloned node.
1335 // Note that some Identity methods call phase->type(this).
1336 // Make sure that the type array is big enough for
1337 // our new node, even though we may throw the node away.
1338 // (This tweaking with igvn only works because x is a new node.)
1339 igvn->set_type(x, t);
1340 // If x is a TypeNode, capture any more-precise type permanently into Node
1341 // otherwise it will be not updated during igvn->transform since
1342 // igvn->type(x) is set to x->Value() already.
1343 x->raise_bottom_type(t);
1344 Node *y = x->Identity(igvn);
1345 if (y != x) {
1346 x = y;
1347 } else {
1348 y = igvn->hash_find(x);
1349 if (y) {
1350 x = y;
1351 } else {
1352 // Else x is a new node we are keeping
1353 // We do not need register_new_node_with_optimizer
1354 // because set_type has already been called.
1355 igvn->_worklist.push(x);
1356 }
1357 }
1358 }
1359 if (x != the_clone && the_clone != NULL)
1360 igvn->remove_dead_node(the_clone);
1361 phi->set_req(i, x);
1362 }
1363 // Record Phi
1364 igvn->register_new_node_with_optimizer(phi);
1365 return phi;
1366 }
1368 //------------------------------Ideal------------------------------------------
1369 // If the load is from Field memory and the pointer is non-null, we can
1370 // zero out the control input.
1371 // If the offset is constant and the base is an object allocation,
1372 // try to hook me up to the exact initializing store.
1373 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1374 Node* p = MemNode::Ideal_common(phase, can_reshape);
1375 if (p) return (p == NodeSentinel) ? NULL : p;
1377 Node* ctrl = in(MemNode::Control);
1378 Node* address = in(MemNode::Address);
1380 // Skip up past a SafePoint control. Cannot do this for Stores because
1381 // pointer stores & cardmarks must stay on the same side of a SafePoint.
1382 if( ctrl != NULL && ctrl->Opcode() == Op_SafePoint &&
1383 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw ) {
1384 ctrl = ctrl->in(0);
1385 set_req(MemNode::Control,ctrl);
1386 }
1388 intptr_t ignore = 0;
1389 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1390 if (base != NULL
1391 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
1392 // Check for useless control edge in some common special cases
1393 if (in(MemNode::Control) != NULL
1394 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
1395 && all_controls_dominate(base, phase->C->start())) {
1396 // A method-invariant, non-null address (constant or 'this' argument).
1397 set_req(MemNode::Control, NULL);
1398 }
1400 if (EliminateAutoBox && can_reshape) {
1401 assert(!phase->type(base)->higher_equal(TypePtr::NULL_PTR), "the autobox pointer should be non-null");
1402 Compile::AliasType* atp = phase->C->alias_type(adr_type());
1403 if (is_autobox_object(atp)) {
1404 Node* result = eliminate_autobox(phase);
1405 if (result != NULL) return result;
1406 }
1407 }
1408 }
1410 Node* mem = in(MemNode::Memory);
1411 const TypePtr *addr_t = phase->type(address)->isa_ptr();
1413 if (addr_t != NULL) {
1414 // try to optimize our memory input
1415 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, phase);
1416 if (opt_mem != mem) {
1417 set_req(MemNode::Memory, opt_mem);
1418 if (phase->type( opt_mem ) == Type::TOP) return NULL;
1419 return this;
1420 }
1421 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
1422 if (can_reshape && opt_mem->is_Phi() &&
1423 (t_oop != NULL) && t_oop->is_known_instance_field()) {
1424 PhaseIterGVN *igvn = phase->is_IterGVN();
1425 if (igvn != NULL && igvn->_worklist.member(opt_mem)) {
1426 // Delay this transformation until memory Phi is processed.
1427 phase->is_IterGVN()->_worklist.push(this);
1428 return NULL;
1429 }
1430 // Split instance field load through Phi.
1431 Node* result = split_through_phi(phase);
1432 if (result != NULL) return result;
1433 }
1434 }
1436 // Check for prior store with a different base or offset; make Load
1437 // independent. Skip through any number of them. Bail out if the stores
1438 // are in an endless dead cycle and report no progress. This is a key
1439 // transform for Reflection. However, if after skipping through the Stores
1440 // we can't then fold up against a prior store do NOT do the transform as
1441 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
1442 // array memory alive twice: once for the hoisted Load and again after the
1443 // bypassed Store. This situation only works if EVERYBODY who does
1444 // anti-dependence work knows how to bypass. I.e. we need all
1445 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
1446 // the alias index stuff. So instead, peek through Stores and IFF we can
1447 // fold up, do so.
1448 Node* prev_mem = find_previous_store(phase);
1449 // Steps (a), (b): Walk past independent stores to find an exact match.
1450 if (prev_mem != NULL && prev_mem != in(MemNode::Memory)) {
1451 // (c) See if we can fold up on the spot, but don't fold up here.
1452 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
1453 // just return a prior value, which is done by Identity calls.
1454 if (can_see_stored_value(prev_mem, phase)) {
1455 // Make ready for step (d):
1456 set_req(MemNode::Memory, prev_mem);
1457 return this;
1458 }
1459 }
1461 return NULL; // No further progress
1462 }
1464 // Helper to recognize certain Klass fields which are invariant across
1465 // some group of array types (e.g., int[] or all T[] where T < Object).
1466 const Type*
1467 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
1468 ciKlass* klass) const {
1469 if (tkls->offset() == Klass::modifier_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1470 // The field is Klass::_modifier_flags. Return its (constant) value.
1471 // (Folds up the 2nd indirection in aClassConstant.getModifiers().)
1472 assert(this->Opcode() == Op_LoadI, "must load an int from _modifier_flags");
1473 return TypeInt::make(klass->modifier_flags());
1474 }
1475 if (tkls->offset() == Klass::access_flags_offset_in_bytes() + (int)sizeof(oopDesc)) {
1476 // The field is Klass::_access_flags. Return its (constant) value.
1477 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
1478 assert(this->Opcode() == Op_LoadI, "must load an int from _access_flags");
1479 return TypeInt::make(klass->access_flags());
1480 }
1481 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)) {
1482 // The field is Klass::_layout_helper. Return its constant value if known.
1483 assert(this->Opcode() == Op_LoadI, "must load an int from _layout_helper");
1484 return TypeInt::make(klass->layout_helper());
1485 }
1487 // No match.
1488 return NULL;
1489 }
1491 //------------------------------Value-----------------------------------------
1492 const Type *LoadNode::Value( PhaseTransform *phase ) const {
1493 // Either input is TOP ==> the result is TOP
1494 Node* mem = in(MemNode::Memory);
1495 const Type *t1 = phase->type(mem);
1496 if (t1 == Type::TOP) return Type::TOP;
1497 Node* adr = in(MemNode::Address);
1498 const TypePtr* tp = phase->type(adr)->isa_ptr();
1499 if (tp == NULL || tp->empty()) return Type::TOP;
1500 int off = tp->offset();
1501 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
1502 Compile* C = phase->C;
1504 // Try to guess loaded type from pointer type
1505 if (tp->base() == Type::AryPtr) {
1506 const Type *t = tp->is_aryptr()->elem();
1507 // Don't do this for integer types. There is only potential profit if
1508 // the element type t is lower than _type; that is, for int types, if _type is
1509 // more restrictive than t. This only happens here if one is short and the other
1510 // char (both 16 bits), and in those cases we've made an intentional decision
1511 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
1512 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
1513 //
1514 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
1515 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
1516 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
1517 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
1518 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
1519 // In fact, that could have been the original type of p1, and p1 could have
1520 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
1521 // expression (LShiftL quux 3) independently optimized to the constant 8.
1522 if ((t->isa_int() == NULL) && (t->isa_long() == NULL)
1523 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
1524 // t might actually be lower than _type, if _type is a unique
1525 // concrete subclass of abstract class t.
1526 // Make sure the reference is not into the header, by comparing
1527 // the offset against the offset of the start of the array's data.
1528 // Different array types begin at slightly different offsets (12 vs. 16).
1529 // We choose T_BYTE as an example base type that is least restrictive
1530 // as to alignment, which will therefore produce the smallest
1531 // possible base offset.
1532 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
1533 if ((uint)off >= (uint)min_base_off) { // is the offset beyond the header?
1534 const Type* jt = t->join(_type);
1535 // In any case, do not allow the join, per se, to empty out the type.
1536 if (jt->empty() && !t->empty()) {
1537 // This can happen if a interface-typed array narrows to a class type.
1538 jt = _type;
1539 }
1541 if (EliminateAutoBox && adr->is_AddP()) {
1542 // The pointers in the autobox arrays are always non-null
1543 Node* base = adr->in(AddPNode::Base);
1544 if (base != NULL &&
1545 !phase->type(base)->higher_equal(TypePtr::NULL_PTR)) {
1546 Compile::AliasType* atp = C->alias_type(base->adr_type());
1547 if (is_autobox_cache(atp)) {
1548 return jt->join(TypePtr::NOTNULL)->is_ptr();
1549 }
1550 }
1551 }
1552 return jt;
1553 }
1554 }
1555 } else if (tp->base() == Type::InstPtr) {
1556 ciEnv* env = C->env();
1557 const TypeInstPtr* tinst = tp->is_instptr();
1558 ciKlass* klass = tinst->klass();
1559 assert( off != Type::OffsetBot ||
1560 // arrays can be cast to Objects
1561 tp->is_oopptr()->klass()->is_java_lang_Object() ||
1562 // unsafe field access may not have a constant offset
1563 C->has_unsafe_access(),
1564 "Field accesses must be precise" );
1565 // For oop loads, we expect the _type to be precise
1566 if (klass == env->String_klass() &&
1567 adr->is_AddP() && off != Type::OffsetBot) {
1568 // For constant Strings treat the final fields as compile time constants.
1569 Node* base = adr->in(AddPNode::Base);
1570 const TypeOopPtr* t = phase->type(base)->isa_oopptr();
1571 if (t != NULL && t->singleton()) {
1572 ciField* field = env->String_klass()->get_field_by_offset(off, false);
1573 if (field != NULL && field->is_final()) {
1574 ciObject* string = t->const_oop();
1575 ciConstant constant = string->as_instance()->field_value(field);
1576 if (constant.basic_type() == T_INT) {
1577 return TypeInt::make(constant.as_int());
1578 } else if (constant.basic_type() == T_ARRAY) {
1579 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1580 return TypeNarrowOop::make_from_constant(constant.as_object(), true);
1581 } else {
1582 return TypeOopPtr::make_from_constant(constant.as_object(), true);
1583 }
1584 }
1585 }
1586 }
1587 }
1588 // Optimizations for constant objects
1589 ciObject* const_oop = tinst->const_oop();
1590 if (const_oop != NULL) {
1591 // For constant CallSites treat the target field as a compile time constant.
1592 if (const_oop->is_call_site()) {
1593 ciCallSite* call_site = const_oop->as_call_site();
1594 ciField* field = call_site->klass()->as_instance_klass()->get_field_by_offset(off, /*is_static=*/ false);
1595 if (field != NULL && field->is_call_site_target()) {
1596 ciMethodHandle* target = call_site->get_target();
1597 if (target != NULL) { // just in case
1598 ciConstant constant(T_OBJECT, target);
1599 const Type* t;
1600 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1601 t = TypeNarrowOop::make_from_constant(constant.as_object(), true);
1602 } else {
1603 t = TypeOopPtr::make_from_constant(constant.as_object(), true);
1604 }
1605 // Add a dependence for invalidation of the optimization.
1606 if (!call_site->is_constant_call_site()) {
1607 C->dependencies()->assert_call_site_target_value(call_site, target);
1608 }
1609 return t;
1610 }
1611 }
1612 }
1613 }
1614 } else if (tp->base() == Type::KlassPtr) {
1615 assert( off != Type::OffsetBot ||
1616 // arrays can be cast to Objects
1617 tp->is_klassptr()->klass()->is_java_lang_Object() ||
1618 // also allow array-loading from the primary supertype
1619 // array during subtype checks
1620 Opcode() == Op_LoadKlass,
1621 "Field accesses must be precise" );
1622 // For klass/static loads, we expect the _type to be precise
1623 }
1625 const TypeKlassPtr *tkls = tp->isa_klassptr();
1626 if (tkls != NULL && !StressReflectiveCode) {
1627 ciKlass* klass = tkls->klass();
1628 if (klass->is_loaded() && tkls->klass_is_exact()) {
1629 // We are loading a field from a Klass metaobject whose identity
1630 // is known at compile time (the type is "exact" or "precise").
1631 // Check for fields we know are maintained as constants by the VM.
1632 if (tkls->offset() == Klass::super_check_offset_offset_in_bytes() + (int)sizeof(oopDesc)) {
1633 // The field is Klass::_super_check_offset. Return its (constant) value.
1634 // (Folds up type checking code.)
1635 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
1636 return TypeInt::make(klass->super_check_offset());
1637 }
1638 // Compute index into primary_supers array
1639 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1640 // Check for overflowing; use unsigned compare to handle the negative case.
1641 if( depth < ciKlass::primary_super_limit() ) {
1642 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1643 // (Folds up type checking code.)
1644 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1645 ciKlass *ss = klass->super_of_depth(depth);
1646 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1647 }
1648 const Type* aift = load_array_final_field(tkls, klass);
1649 if (aift != NULL) return aift;
1650 if (tkls->offset() == in_bytes(arrayKlass::component_mirror_offset()) + (int)sizeof(oopDesc)
1651 && klass->is_array_klass()) {
1652 // The field is arrayKlass::_component_mirror. Return its (constant) value.
1653 // (Folds up aClassConstant.getComponentType, common in Arrays.copyOf.)
1654 assert(Opcode() == Op_LoadP, "must load an oop from _component_mirror");
1655 return TypeInstPtr::make(klass->as_array_klass()->component_mirror());
1656 }
1657 if (tkls->offset() == Klass::java_mirror_offset_in_bytes() + (int)sizeof(oopDesc)) {
1658 // The field is Klass::_java_mirror. Return its (constant) value.
1659 // (Folds up the 2nd indirection in anObjConstant.getClass().)
1660 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
1661 return TypeInstPtr::make(klass->java_mirror());
1662 }
1663 }
1665 // We can still check if we are loading from the primary_supers array at a
1666 // shallow enough depth. Even though the klass is not exact, entries less
1667 // than or equal to its super depth are correct.
1668 if (klass->is_loaded() ) {
1669 ciType *inner = klass->klass();
1670 while( inner->is_obj_array_klass() )
1671 inner = inner->as_obj_array_klass()->base_element_type();
1672 if( inner->is_instance_klass() &&
1673 !inner->as_instance_klass()->flags().is_interface() ) {
1674 // Compute index into primary_supers array
1675 juint depth = (tkls->offset() - (Klass::primary_supers_offset_in_bytes() + (int)sizeof(oopDesc))) / sizeof(klassOop);
1676 // Check for overflowing; use unsigned compare to handle the negative case.
1677 if( depth < ciKlass::primary_super_limit() &&
1678 depth <= klass->super_depth() ) { // allow self-depth checks to handle self-check case
1679 // The field is an element of Klass::_primary_supers. Return its (constant) value.
1680 // (Folds up type checking code.)
1681 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
1682 ciKlass *ss = klass->super_of_depth(depth);
1683 return ss ? TypeKlassPtr::make(ss) : TypePtr::NULL_PTR;
1684 }
1685 }
1686 }
1688 // If the type is enough to determine that the thing is not an array,
1689 // we can give the layout_helper a positive interval type.
1690 // This will help short-circuit some reflective code.
1691 if (tkls->offset() == Klass::layout_helper_offset_in_bytes() + (int)sizeof(oopDesc)
1692 && !klass->is_array_klass() // not directly typed as an array
1693 && !klass->is_interface() // specifically not Serializable & Cloneable
1694 && !klass->is_java_lang_Object() // not the supertype of all T[]
1695 ) {
1696 // Note: When interfaces are reliable, we can narrow the interface
1697 // test to (klass != Serializable && klass != Cloneable).
1698 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
1699 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
1700 // The key property of this type is that it folds up tests
1701 // for array-ness, since it proves that the layout_helper is positive.
1702 // Thus, a generic value like the basic object layout helper works fine.
1703 return TypeInt::make(min_size, max_jint, Type::WidenMin);
1704 }
1705 }
1707 // If we are loading from a freshly-allocated object, produce a zero,
1708 // if the load is provably beyond the header of the object.
1709 // (Also allow a variable load from a fresh array to produce zero.)
1710 const TypeOopPtr *tinst = tp->isa_oopptr();
1711 bool is_instance = (tinst != NULL) && tinst->is_known_instance_field();
1712 if (ReduceFieldZeroing || is_instance) {
1713 Node* value = can_see_stored_value(mem,phase);
1714 if (value != NULL && value->is_Con())
1715 return value->bottom_type();
1716 }
1718 if (is_instance) {
1719 // If we have an instance type and our memory input is the
1720 // programs's initial memory state, there is no matching store,
1721 // so just return a zero of the appropriate type
1722 Node *mem = in(MemNode::Memory);
1723 if (mem->is_Parm() && mem->in(0)->is_Start()) {
1724 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
1725 return Type::get_zero_type(_type->basic_type());
1726 }
1727 }
1728 return _type;
1729 }
1731 //------------------------------match_edge-------------------------------------
1732 // Do we Match on this edge index or not? Match only the address.
1733 uint LoadNode::match_edge(uint idx) const {
1734 return idx == MemNode::Address;
1735 }
1737 //--------------------------LoadBNode::Ideal--------------------------------------
1738 //
1739 // If the previous store is to the same address as this load,
1740 // and the value stored was larger than a byte, replace this load
1741 // with the value stored truncated to a byte. If no truncation is
1742 // needed, the replacement is done in LoadNode::Identity().
1743 //
1744 Node *LoadBNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1745 Node* mem = in(MemNode::Memory);
1746 Node* value = can_see_stored_value(mem,phase);
1747 if( value && !phase->type(value)->higher_equal( _type ) ) {
1748 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(24)) );
1749 return new (phase->C, 3) RShiftINode(result, phase->intcon(24));
1750 }
1751 // Identity call will handle the case where truncation is not needed.
1752 return LoadNode::Ideal(phase, can_reshape);
1753 }
1755 //--------------------------LoadUBNode::Ideal-------------------------------------
1756 //
1757 // If the previous store is to the same address as this load,
1758 // and the value stored was larger than a byte, replace this load
1759 // with the value stored truncated to a byte. If no truncation is
1760 // needed, the replacement is done in LoadNode::Identity().
1761 //
1762 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
1763 Node* mem = in(MemNode::Memory);
1764 Node* value = can_see_stored_value(mem, phase);
1765 if (value && !phase->type(value)->higher_equal(_type))
1766 return new (phase->C, 3) AndINode(value, phase->intcon(0xFF));
1767 // Identity call will handle the case where truncation is not needed.
1768 return LoadNode::Ideal(phase, can_reshape);
1769 }
1771 //--------------------------LoadUSNode::Ideal-------------------------------------
1772 //
1773 // If the previous store is to the same address as this load,
1774 // and the value stored was larger than a char, replace this load
1775 // with the value stored truncated to a char. If no truncation is
1776 // needed, the replacement is done in LoadNode::Identity().
1777 //
1778 Node *LoadUSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1779 Node* mem = in(MemNode::Memory);
1780 Node* value = can_see_stored_value(mem,phase);
1781 if( value && !phase->type(value)->higher_equal( _type ) )
1782 return new (phase->C, 3) AndINode(value,phase->intcon(0xFFFF));
1783 // Identity call will handle the case where truncation is not needed.
1784 return LoadNode::Ideal(phase, can_reshape);
1785 }
1787 //--------------------------LoadSNode::Ideal--------------------------------------
1788 //
1789 // If the previous store is to the same address as this load,
1790 // and the value stored was larger than a short, replace this load
1791 // with the value stored truncated to a short. If no truncation is
1792 // needed, the replacement is done in LoadNode::Identity().
1793 //
1794 Node *LoadSNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1795 Node* mem = in(MemNode::Memory);
1796 Node* value = can_see_stored_value(mem,phase);
1797 if( value && !phase->type(value)->higher_equal( _type ) ) {
1798 Node *result = phase->transform( new (phase->C, 3) LShiftINode(value, phase->intcon(16)) );
1799 return new (phase->C, 3) RShiftINode(result, phase->intcon(16));
1800 }
1801 // Identity call will handle the case where truncation is not needed.
1802 return LoadNode::Ideal(phase, can_reshape);
1803 }
1805 //=============================================================================
1806 //----------------------------LoadKlassNode::make------------------------------
1807 // Polymorphic factory method:
1808 Node *LoadKlassNode::make( PhaseGVN& gvn, Node *mem, Node *adr, const TypePtr* at, const TypeKlassPtr *tk ) {
1809 Compile* C = gvn.C;
1810 Node *ctl = NULL;
1811 // sanity check the alias category against the created node type
1812 const TypeOopPtr *adr_type = adr->bottom_type()->isa_oopptr();
1813 assert(adr_type != NULL, "expecting TypeOopPtr");
1814 #ifdef _LP64
1815 if (adr_type->is_ptr_to_narrowoop()) {
1816 Node* load_klass = gvn.transform(new (C, 3) LoadNKlassNode(ctl, mem, adr, at, tk->make_narrowoop()));
1817 return new (C, 2) DecodeNNode(load_klass, load_klass->bottom_type()->make_ptr());
1818 }
1819 #endif
1820 assert(!adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
1821 return new (C, 3) LoadKlassNode(ctl, mem, adr, at, tk);
1822 }
1824 //------------------------------Value------------------------------------------
1825 const Type *LoadKlassNode::Value( PhaseTransform *phase ) const {
1826 return klass_value_common(phase);
1827 }
1829 const Type *LoadNode::klass_value_common( PhaseTransform *phase ) const {
1830 // Either input is TOP ==> the result is TOP
1831 const Type *t1 = phase->type( in(MemNode::Memory) );
1832 if (t1 == Type::TOP) return Type::TOP;
1833 Node *adr = in(MemNode::Address);
1834 const Type *t2 = phase->type( adr );
1835 if (t2 == Type::TOP) return Type::TOP;
1836 const TypePtr *tp = t2->is_ptr();
1837 if (TypePtr::above_centerline(tp->ptr()) ||
1838 tp->ptr() == TypePtr::Null) return Type::TOP;
1840 // Return a more precise klass, if possible
1841 const TypeInstPtr *tinst = tp->isa_instptr();
1842 if (tinst != NULL) {
1843 ciInstanceKlass* ik = tinst->klass()->as_instance_klass();
1844 int offset = tinst->offset();
1845 if (ik == phase->C->env()->Class_klass()
1846 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1847 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1848 // We are loading a special hidden field from a Class mirror object,
1849 // the field which points to the VM's Klass metaobject.
1850 ciType* t = tinst->java_mirror_type();
1851 // java_mirror_type returns non-null for compile-time Class constants.
1852 if (t != NULL) {
1853 // constant oop => constant klass
1854 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
1855 return TypeKlassPtr::make(ciArrayKlass::make(t));
1856 }
1857 if (!t->is_klass()) {
1858 // a primitive Class (e.g., int.class) has NULL for a klass field
1859 return TypePtr::NULL_PTR;
1860 }
1861 // (Folds up the 1st indirection in aClassConstant.getModifiers().)
1862 return TypeKlassPtr::make(t->as_klass());
1863 }
1864 // non-constant mirror, so we can't tell what's going on
1865 }
1866 if( !ik->is_loaded() )
1867 return _type; // Bail out if not loaded
1868 if (offset == oopDesc::klass_offset_in_bytes()) {
1869 if (tinst->klass_is_exact()) {
1870 return TypeKlassPtr::make(ik);
1871 }
1872 // See if we can become precise: no subklasses and no interface
1873 // (Note: We need to support verified interfaces.)
1874 if (!ik->is_interface() && !ik->has_subklass()) {
1875 //assert(!UseExactTypes, "this code should be useless with exact types");
1876 // Add a dependence; if any subclass added we need to recompile
1877 if (!ik->is_final()) {
1878 // %%% should use stronger assert_unique_concrete_subtype instead
1879 phase->C->dependencies()->assert_leaf_type(ik);
1880 }
1881 // Return precise klass
1882 return TypeKlassPtr::make(ik);
1883 }
1885 // Return root of possible klass
1886 return TypeKlassPtr::make(TypePtr::NotNull, ik, 0/*offset*/);
1887 }
1888 }
1890 // Check for loading klass from an array
1891 const TypeAryPtr *tary = tp->isa_aryptr();
1892 if( tary != NULL ) {
1893 ciKlass *tary_klass = tary->klass();
1894 if (tary_klass != NULL // can be NULL when at BOTTOM or TOP
1895 && tary->offset() == oopDesc::klass_offset_in_bytes()) {
1896 if (tary->klass_is_exact()) {
1897 return TypeKlassPtr::make(tary_klass);
1898 }
1899 ciArrayKlass *ak = tary->klass()->as_array_klass();
1900 // If the klass is an object array, we defer the question to the
1901 // array component klass.
1902 if( ak->is_obj_array_klass() ) {
1903 assert( ak->is_loaded(), "" );
1904 ciKlass *base_k = ak->as_obj_array_klass()->base_element_klass();
1905 if( base_k->is_loaded() && base_k->is_instance_klass() ) {
1906 ciInstanceKlass* ik = base_k->as_instance_klass();
1907 // See if we can become precise: no subklasses and no interface
1908 if (!ik->is_interface() && !ik->has_subklass()) {
1909 //assert(!UseExactTypes, "this code should be useless with exact types");
1910 // Add a dependence; if any subclass added we need to recompile
1911 if (!ik->is_final()) {
1912 phase->C->dependencies()->assert_leaf_type(ik);
1913 }
1914 // Return precise array klass
1915 return TypeKlassPtr::make(ak);
1916 }
1917 }
1918 return TypeKlassPtr::make(TypePtr::NotNull, ak, 0/*offset*/);
1919 } else { // Found a type-array?
1920 //assert(!UseExactTypes, "this code should be useless with exact types");
1921 assert( ak->is_type_array_klass(), "" );
1922 return TypeKlassPtr::make(ak); // These are always precise
1923 }
1924 }
1925 }
1927 // Check for loading klass from an array klass
1928 const TypeKlassPtr *tkls = tp->isa_klassptr();
1929 if (tkls != NULL && !StressReflectiveCode) {
1930 ciKlass* klass = tkls->klass();
1931 if( !klass->is_loaded() )
1932 return _type; // Bail out if not loaded
1933 if( klass->is_obj_array_klass() &&
1934 (uint)tkls->offset() == objArrayKlass::element_klass_offset_in_bytes() + sizeof(oopDesc)) {
1935 ciKlass* elem = klass->as_obj_array_klass()->element_klass();
1936 // // Always returning precise element type is incorrect,
1937 // // e.g., element type could be object and array may contain strings
1938 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
1940 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
1941 // according to the element type's subclassing.
1942 return TypeKlassPtr::make(tkls->ptr(), elem, 0/*offset*/);
1943 }
1944 if( klass->is_instance_klass() && tkls->klass_is_exact() &&
1945 (uint)tkls->offset() == Klass::super_offset_in_bytes() + sizeof(oopDesc)) {
1946 ciKlass* sup = klass->as_instance_klass()->super();
1947 // The field is Klass::_super. Return its (constant) value.
1948 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
1949 return sup ? TypeKlassPtr::make(sup) : TypePtr::NULL_PTR;
1950 }
1951 }
1953 // Bailout case
1954 return LoadNode::Value(phase);
1955 }
1957 //------------------------------Identity---------------------------------------
1958 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
1959 // Also feed through the klass in Allocate(...klass...)._klass.
1960 Node* LoadKlassNode::Identity( PhaseTransform *phase ) {
1961 return klass_identity_common(phase);
1962 }
1964 Node* LoadNode::klass_identity_common(PhaseTransform *phase ) {
1965 Node* x = LoadNode::Identity(phase);
1966 if (x != this) return x;
1968 // Take apart the address into an oop and and offset.
1969 // Return 'this' if we cannot.
1970 Node* adr = in(MemNode::Address);
1971 intptr_t offset = 0;
1972 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
1973 if (base == NULL) return this;
1974 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
1975 if (toop == NULL) return this;
1977 // We can fetch the klass directly through an AllocateNode.
1978 // This works even if the klass is not constant (clone or newArray).
1979 if (offset == oopDesc::klass_offset_in_bytes()) {
1980 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
1981 if (allocated_klass != NULL) {
1982 return allocated_klass;
1983 }
1984 }
1986 // Simplify k.java_mirror.as_klass to plain k, where k is a klassOop.
1987 // Simplify ak.component_mirror.array_klass to plain ak, ak an arrayKlass.
1988 // See inline_native_Class_query for occurrences of these patterns.
1989 // Java Example: x.getClass().isAssignableFrom(y)
1990 // Java Example: Array.newInstance(x.getClass().getComponentType(), n)
1991 //
1992 // This improves reflective code, often making the Class
1993 // mirror go completely dead. (Current exception: Class
1994 // mirrors may appear in debug info, but we could clean them out by
1995 // introducing a new debug info operator for klassOop.java_mirror).
1996 if (toop->isa_instptr() && toop->klass() == phase->C->env()->Class_klass()
1997 && (offset == java_lang_Class::klass_offset_in_bytes() ||
1998 offset == java_lang_Class::array_klass_offset_in_bytes())) {
1999 // We are loading a special hidden field from a Class mirror,
2000 // the field which points to its Klass or arrayKlass metaobject.
2001 if (base->is_Load()) {
2002 Node* adr2 = base->in(MemNode::Address);
2003 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2004 if (tkls != NULL && !tkls->empty()
2005 && (tkls->klass()->is_instance_klass() ||
2006 tkls->klass()->is_array_klass())
2007 && adr2->is_AddP()
2008 ) {
2009 int mirror_field = Klass::java_mirror_offset_in_bytes();
2010 if (offset == java_lang_Class::array_klass_offset_in_bytes()) {
2011 mirror_field = in_bytes(arrayKlass::component_mirror_offset());
2012 }
2013 if (tkls->offset() == mirror_field + (int)sizeof(oopDesc)) {
2014 return adr2->in(AddPNode::Base);
2015 }
2016 }
2017 }
2018 }
2020 return this;
2021 }
2024 //------------------------------Value------------------------------------------
2025 const Type *LoadNKlassNode::Value( PhaseTransform *phase ) const {
2026 const Type *t = klass_value_common(phase);
2027 if (t == Type::TOP)
2028 return t;
2030 return t->make_narrowoop();
2031 }
2033 //------------------------------Identity---------------------------------------
2034 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2035 // Also feed through the klass in Allocate(...klass...)._klass.
2036 Node* LoadNKlassNode::Identity( PhaseTransform *phase ) {
2037 Node *x = klass_identity_common(phase);
2039 const Type *t = phase->type( x );
2040 if( t == Type::TOP ) return x;
2041 if( t->isa_narrowoop()) return x;
2043 return phase->transform(new (phase->C, 2) EncodePNode(x, t->make_narrowoop()));
2044 }
2046 //------------------------------Value-----------------------------------------
2047 const Type *LoadRangeNode::Value( PhaseTransform *phase ) const {
2048 // Either input is TOP ==> the result is TOP
2049 const Type *t1 = phase->type( in(MemNode::Memory) );
2050 if( t1 == Type::TOP ) return Type::TOP;
2051 Node *adr = in(MemNode::Address);
2052 const Type *t2 = phase->type( adr );
2053 if( t2 == Type::TOP ) return Type::TOP;
2054 const TypePtr *tp = t2->is_ptr();
2055 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2056 const TypeAryPtr *tap = tp->isa_aryptr();
2057 if( !tap ) return _type;
2058 return tap->size();
2059 }
2061 //-------------------------------Ideal---------------------------------------
2062 // Feed through the length in AllocateArray(...length...)._length.
2063 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2064 Node* p = MemNode::Ideal_common(phase, can_reshape);
2065 if (p) return (p == NodeSentinel) ? NULL : p;
2067 // Take apart the address into an oop and and offset.
2068 // Return 'this' if we cannot.
2069 Node* adr = in(MemNode::Address);
2070 intptr_t offset = 0;
2071 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2072 if (base == NULL) return NULL;
2073 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2074 if (tary == NULL) return NULL;
2076 // We can fetch the length directly through an AllocateArrayNode.
2077 // This works even if the length is not constant (clone or newArray).
2078 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2079 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2080 if (alloc != NULL) {
2081 Node* allocated_length = alloc->Ideal_length();
2082 Node* len = alloc->make_ideal_length(tary, phase);
2083 if (allocated_length != len) {
2084 // New CastII improves on this.
2085 return len;
2086 }
2087 }
2088 }
2090 return NULL;
2091 }
2093 //------------------------------Identity---------------------------------------
2094 // Feed through the length in AllocateArray(...length...)._length.
2095 Node* LoadRangeNode::Identity( PhaseTransform *phase ) {
2096 Node* x = LoadINode::Identity(phase);
2097 if (x != this) return x;
2099 // Take apart the address into an oop and and offset.
2100 // Return 'this' if we cannot.
2101 Node* adr = in(MemNode::Address);
2102 intptr_t offset = 0;
2103 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2104 if (base == NULL) return this;
2105 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2106 if (tary == NULL) return this;
2108 // We can fetch the length directly through an AllocateArrayNode.
2109 // This works even if the length is not constant (clone or newArray).
2110 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2111 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base, phase);
2112 if (alloc != NULL) {
2113 Node* allocated_length = alloc->Ideal_length();
2114 // Do not allow make_ideal_length to allocate a CastII node.
2115 Node* len = alloc->make_ideal_length(tary, phase, false);
2116 if (allocated_length == len) {
2117 // Return allocated_length only if it would not be improved by a CastII.
2118 return allocated_length;
2119 }
2120 }
2121 }
2123 return this;
2125 }
2127 //=============================================================================
2128 //---------------------------StoreNode::make-----------------------------------
2129 // Polymorphic factory method:
2130 StoreNode* StoreNode::make( PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt ) {
2131 Compile* C = gvn.C;
2132 assert( C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2133 ctl != NULL, "raw memory operations should have control edge");
2135 switch (bt) {
2136 case T_BOOLEAN:
2137 case T_BYTE: return new (C, 4) StoreBNode(ctl, mem, adr, adr_type, val);
2138 case T_INT: return new (C, 4) StoreINode(ctl, mem, adr, adr_type, val);
2139 case T_CHAR:
2140 case T_SHORT: return new (C, 4) StoreCNode(ctl, mem, adr, adr_type, val);
2141 case T_LONG: return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val);
2142 case T_FLOAT: return new (C, 4) StoreFNode(ctl, mem, adr, adr_type, val);
2143 case T_DOUBLE: return new (C, 4) StoreDNode(ctl, mem, adr, adr_type, val);
2144 case T_ADDRESS:
2145 case T_OBJECT:
2146 #ifdef _LP64
2147 if (adr->bottom_type()->is_ptr_to_narrowoop() ||
2148 (UseCompressedOops && val->bottom_type()->isa_klassptr() &&
2149 adr->bottom_type()->isa_rawptr())) {
2150 val = gvn.transform(new (C, 2) EncodePNode(val, val->bottom_type()->make_narrowoop()));
2151 return new (C, 4) StoreNNode(ctl, mem, adr, adr_type, val);
2152 } else
2153 #endif
2154 {
2155 return new (C, 4) StorePNode(ctl, mem, adr, adr_type, val);
2156 }
2157 }
2158 ShouldNotReachHere();
2159 return (StoreNode*)NULL;
2160 }
2162 StoreLNode* StoreLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val) {
2163 bool require_atomic = true;
2164 return new (C, 4) StoreLNode(ctl, mem, adr, adr_type, val, require_atomic);
2165 }
2168 //--------------------------bottom_type----------------------------------------
2169 const Type *StoreNode::bottom_type() const {
2170 return Type::MEMORY;
2171 }
2173 //------------------------------hash-------------------------------------------
2174 uint StoreNode::hash() const {
2175 // unroll addition of interesting fields
2176 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2178 // Since they are not commoned, do not hash them:
2179 return NO_HASH;
2180 }
2182 //------------------------------Ideal------------------------------------------
2183 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
2184 // When a store immediately follows a relevant allocation/initialization,
2185 // try to capture it into the initialization, or hoist it above.
2186 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2187 Node* p = MemNode::Ideal_common(phase, can_reshape);
2188 if (p) return (p == NodeSentinel) ? NULL : p;
2190 Node* mem = in(MemNode::Memory);
2191 Node* address = in(MemNode::Address);
2193 // Back-to-back stores to same address? Fold em up. Generally
2194 // unsafe if I have intervening uses... Also disallowed for StoreCM
2195 // since they must follow each StoreP operation. Redundant StoreCMs
2196 // are eliminated just before matching in final_graph_reshape.
2197 if (mem->is_Store() && phase->eqv_uncast(mem->in(MemNode::Address), address) &&
2198 mem->Opcode() != Op_StoreCM) {
2199 // Looking at a dead closed cycle of memory?
2200 assert(mem != mem->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
2202 assert(Opcode() == mem->Opcode() ||
2203 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw,
2204 "no mismatched stores, except on raw memory");
2206 if (mem->outcnt() == 1 && // check for intervening uses
2207 mem->as_Store()->memory_size() <= this->memory_size()) {
2208 // If anybody other than 'this' uses 'mem', we cannot fold 'mem' away.
2209 // For example, 'mem' might be the final state at a conditional return.
2210 // Or, 'mem' might be used by some node which is live at the same time
2211 // 'this' is live, which might be unschedulable. So, require exactly
2212 // ONE user, the 'this' store, until such time as we clone 'mem' for
2213 // each of 'mem's uses (thus making the exactly-1-user-rule hold true).
2214 if (can_reshape) { // (%%% is this an anachronism?)
2215 set_req_X(MemNode::Memory, mem->in(MemNode::Memory),
2216 phase->is_IterGVN());
2217 } else {
2218 // It's OK to do this in the parser, since DU info is always accurate,
2219 // and the parser always refers to nodes via SafePointNode maps.
2220 set_req(MemNode::Memory, mem->in(MemNode::Memory));
2221 }
2222 return this;
2223 }
2224 }
2226 // Capture an unaliased, unconditional, simple store into an initializer.
2227 // Or, if it is independent of the allocation, hoist it above the allocation.
2228 if (ReduceFieldZeroing && /*can_reshape &&*/
2229 mem->is_Proj() && mem->in(0)->is_Initialize()) {
2230 InitializeNode* init = mem->in(0)->as_Initialize();
2231 intptr_t offset = init->can_capture_store(this, phase);
2232 if (offset > 0) {
2233 Node* moved = init->capture_store(this, offset, phase);
2234 // If the InitializeNode captured me, it made a raw copy of me,
2235 // and I need to disappear.
2236 if (moved != NULL) {
2237 // %%% hack to ensure that Ideal returns a new node:
2238 mem = MergeMemNode::make(phase->C, mem);
2239 return mem; // fold me away
2240 }
2241 }
2242 }
2244 return NULL; // No further progress
2245 }
2247 //------------------------------Value-----------------------------------------
2248 const Type *StoreNode::Value( PhaseTransform *phase ) const {
2249 // Either input is TOP ==> the result is TOP
2250 const Type *t1 = phase->type( in(MemNode::Memory) );
2251 if( t1 == Type::TOP ) return Type::TOP;
2252 const Type *t2 = phase->type( in(MemNode::Address) );
2253 if( t2 == Type::TOP ) return Type::TOP;
2254 const Type *t3 = phase->type( in(MemNode::ValueIn) );
2255 if( t3 == Type::TOP ) return Type::TOP;
2256 return Type::MEMORY;
2257 }
2259 //------------------------------Identity---------------------------------------
2260 // Remove redundant stores:
2261 // Store(m, p, Load(m, p)) changes to m.
2262 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
2263 Node *StoreNode::Identity( PhaseTransform *phase ) {
2264 Node* mem = in(MemNode::Memory);
2265 Node* adr = in(MemNode::Address);
2266 Node* val = in(MemNode::ValueIn);
2268 // Load then Store? Then the Store is useless
2269 if (val->is_Load() &&
2270 phase->eqv_uncast( val->in(MemNode::Address), adr ) &&
2271 phase->eqv_uncast( val->in(MemNode::Memory ), mem ) &&
2272 val->as_Load()->store_Opcode() == Opcode()) {
2273 return mem;
2274 }
2276 // Two stores in a row of the same value?
2277 if (mem->is_Store() &&
2278 phase->eqv_uncast( mem->in(MemNode::Address), adr ) &&
2279 phase->eqv_uncast( mem->in(MemNode::ValueIn), val ) &&
2280 mem->Opcode() == Opcode()) {
2281 return mem;
2282 }
2284 // Store of zero anywhere into a freshly-allocated object?
2285 // Then the store is useless.
2286 // (It must already have been captured by the InitializeNode.)
2287 if (ReduceFieldZeroing && phase->type(val)->is_zero_type()) {
2288 // a newly allocated object is already all-zeroes everywhere
2289 if (mem->is_Proj() && mem->in(0)->is_Allocate()) {
2290 return mem;
2291 }
2293 // the store may also apply to zero-bits in an earlier object
2294 Node* prev_mem = find_previous_store(phase);
2295 // Steps (a), (b): Walk past independent stores to find an exact match.
2296 if (prev_mem != NULL) {
2297 Node* prev_val = can_see_stored_value(prev_mem, phase);
2298 if (prev_val != NULL && phase->eqv(prev_val, val)) {
2299 // prev_val and val might differ by a cast; it would be good
2300 // to keep the more informative of the two.
2301 return mem;
2302 }
2303 }
2304 }
2306 return this;
2307 }
2309 //------------------------------match_edge-------------------------------------
2310 // Do we Match on this edge index or not? Match only memory & value
2311 uint StoreNode::match_edge(uint idx) const {
2312 return idx == MemNode::Address || idx == MemNode::ValueIn;
2313 }
2315 //------------------------------cmp--------------------------------------------
2316 // Do not common stores up together. They generally have to be split
2317 // back up anyways, so do not bother.
2318 uint StoreNode::cmp( const Node &n ) const {
2319 return (&n == this); // Always fail except on self
2320 }
2322 //------------------------------Ideal_masked_input-----------------------------
2323 // Check for a useless mask before a partial-word store
2324 // (StoreB ... (AndI valIn conIa) )
2325 // If (conIa & mask == mask) this simplifies to
2326 // (StoreB ... (valIn) )
2327 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
2328 Node *val = in(MemNode::ValueIn);
2329 if( val->Opcode() == Op_AndI ) {
2330 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2331 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
2332 set_req(MemNode::ValueIn, val->in(1));
2333 return this;
2334 }
2335 }
2336 return NULL;
2337 }
2340 //------------------------------Ideal_sign_extended_input----------------------
2341 // Check for useless sign-extension before a partial-word store
2342 // (StoreB ... (RShiftI _ (LShiftI _ valIn conIL ) conIR) )
2343 // If (conIL == conIR && conIR <= num_bits) this simplifies to
2344 // (StoreB ... (valIn) )
2345 Node *StoreNode::Ideal_sign_extended_input(PhaseGVN *phase, int num_bits) {
2346 Node *val = in(MemNode::ValueIn);
2347 if( val->Opcode() == Op_RShiftI ) {
2348 const TypeInt *t = phase->type( val->in(2) )->isa_int();
2349 if( t && t->is_con() && (t->get_con() <= num_bits) ) {
2350 Node *shl = val->in(1);
2351 if( shl->Opcode() == Op_LShiftI ) {
2352 const TypeInt *t2 = phase->type( shl->in(2) )->isa_int();
2353 if( t2 && t2->is_con() && (t2->get_con() == t->get_con()) ) {
2354 set_req(MemNode::ValueIn, shl->in(1));
2355 return this;
2356 }
2357 }
2358 }
2359 }
2360 return NULL;
2361 }
2363 //------------------------------value_never_loaded-----------------------------------
2364 // Determine whether there are any possible loads of the value stored.
2365 // For simplicity, we actually check if there are any loads from the
2366 // address stored to, not just for loads of the value stored by this node.
2367 //
2368 bool StoreNode::value_never_loaded( PhaseTransform *phase) const {
2369 Node *adr = in(Address);
2370 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
2371 if (adr_oop == NULL)
2372 return false;
2373 if (!adr_oop->is_known_instance_field())
2374 return false; // if not a distinct instance, there may be aliases of the address
2375 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
2376 Node *use = adr->fast_out(i);
2377 int opc = use->Opcode();
2378 if (use->is_Load() || use->is_LoadStore()) {
2379 return false;
2380 }
2381 }
2382 return true;
2383 }
2385 //=============================================================================
2386 //------------------------------Ideal------------------------------------------
2387 // If the store is from an AND mask that leaves the low bits untouched, then
2388 // we can skip the AND operation. If the store is from a sign-extension
2389 // (a left shift, then right shift) we can skip both.
2390 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
2391 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
2392 if( progress != NULL ) return progress;
2394 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
2395 if( progress != NULL ) return progress;
2397 // Finally check the default case
2398 return StoreNode::Ideal(phase, can_reshape);
2399 }
2401 //=============================================================================
2402 //------------------------------Ideal------------------------------------------
2403 // If the store is from an AND mask that leaves the low bits untouched, then
2404 // we can skip the AND operation
2405 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
2406 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
2407 if( progress != NULL ) return progress;
2409 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
2410 if( progress != NULL ) return progress;
2412 // Finally check the default case
2413 return StoreNode::Ideal(phase, can_reshape);
2414 }
2416 //=============================================================================
2417 //------------------------------Identity---------------------------------------
2418 Node *StoreCMNode::Identity( PhaseTransform *phase ) {
2419 // No need to card mark when storing a null ptr
2420 Node* my_store = in(MemNode::OopStore);
2421 if (my_store->is_Store()) {
2422 const Type *t1 = phase->type( my_store->in(MemNode::ValueIn) );
2423 if( t1 == TypePtr::NULL_PTR ) {
2424 return in(MemNode::Memory);
2425 }
2426 }
2427 return this;
2428 }
2430 //=============================================================================
2431 //------------------------------Ideal---------------------------------------
2432 Node *StoreCMNode::Ideal(PhaseGVN *phase, bool can_reshape){
2433 Node* progress = StoreNode::Ideal(phase, can_reshape);
2434 if (progress != NULL) return progress;
2436 Node* my_store = in(MemNode::OopStore);
2437 if (my_store->is_MergeMem()) {
2438 Node* mem = my_store->as_MergeMem()->memory_at(oop_alias_idx());
2439 set_req(MemNode::OopStore, mem);
2440 return this;
2441 }
2443 return NULL;
2444 }
2446 //------------------------------Value-----------------------------------------
2447 const Type *StoreCMNode::Value( PhaseTransform *phase ) const {
2448 // Either input is TOP ==> the result is TOP
2449 const Type *t = phase->type( in(MemNode::Memory) );
2450 if( t == Type::TOP ) return Type::TOP;
2451 t = phase->type( in(MemNode::Address) );
2452 if( t == Type::TOP ) return Type::TOP;
2453 t = phase->type( in(MemNode::ValueIn) );
2454 if( t == Type::TOP ) return Type::TOP;
2455 // If extra input is TOP ==> the result is TOP
2456 t = phase->type( in(MemNode::OopStore) );
2457 if( t == Type::TOP ) return Type::TOP;
2459 return StoreNode::Value( phase );
2460 }
2463 //=============================================================================
2464 //----------------------------------SCMemProjNode------------------------------
2465 const Type * SCMemProjNode::Value( PhaseTransform *phase ) const
2466 {
2467 return bottom_type();
2468 }
2470 //=============================================================================
2471 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : Node(5) {
2472 init_req(MemNode::Control, c );
2473 init_req(MemNode::Memory , mem);
2474 init_req(MemNode::Address, adr);
2475 init_req(MemNode::ValueIn, val);
2476 init_req( ExpectedIn, ex );
2477 init_class_id(Class_LoadStore);
2479 }
2481 //=============================================================================
2482 //-------------------------------adr_type--------------------------------------
2483 // Do we Match on this edge index or not? Do not match memory
2484 const TypePtr* ClearArrayNode::adr_type() const {
2485 Node *adr = in(3);
2486 return MemNode::calculate_adr_type(adr->bottom_type());
2487 }
2489 //------------------------------match_edge-------------------------------------
2490 // Do we Match on this edge index or not? Do not match memory
2491 uint ClearArrayNode::match_edge(uint idx) const {
2492 return idx > 1;
2493 }
2495 //------------------------------Identity---------------------------------------
2496 // Clearing a zero length array does nothing
2497 Node *ClearArrayNode::Identity( PhaseTransform *phase ) {
2498 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
2499 }
2501 //------------------------------Idealize---------------------------------------
2502 // Clearing a short array is faster with stores
2503 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape){
2504 const int unit = BytesPerLong;
2505 const TypeX* t = phase->type(in(2))->isa_intptr_t();
2506 if (!t) return NULL;
2507 if (!t->is_con()) return NULL;
2508 intptr_t raw_count = t->get_con();
2509 intptr_t size = raw_count;
2510 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
2511 // Clearing nothing uses the Identity call.
2512 // Negative clears are possible on dead ClearArrays
2513 // (see jck test stmt114.stmt11402.val).
2514 if (size <= 0 || size % unit != 0) return NULL;
2515 intptr_t count = size / unit;
2516 // Length too long; use fast hardware clear
2517 if (size > Matcher::init_array_short_size) return NULL;
2518 Node *mem = in(1);
2519 if( phase->type(mem)==Type::TOP ) return NULL;
2520 Node *adr = in(3);
2521 const Type* at = phase->type(adr);
2522 if( at==Type::TOP ) return NULL;
2523 const TypePtr* atp = at->isa_ptr();
2524 // adjust atp to be the correct array element address type
2525 if (atp == NULL) atp = TypePtr::BOTTOM;
2526 else atp = atp->add_offset(Type::OffsetBot);
2527 // Get base for derived pointer purposes
2528 if( adr->Opcode() != Op_AddP ) Unimplemented();
2529 Node *base = adr->in(1);
2531 Node *zero = phase->makecon(TypeLong::ZERO);
2532 Node *off = phase->MakeConX(BytesPerLong);
2533 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2534 count--;
2535 while( count-- ) {
2536 mem = phase->transform(mem);
2537 adr = phase->transform(new (phase->C, 4) AddPNode(base,adr,off));
2538 mem = new (phase->C, 4) StoreLNode(in(0),mem,adr,atp,zero);
2539 }
2540 return mem;
2541 }
2543 //----------------------------step_through----------------------------------
2544 // Return allocation input memory edge if it is different instance
2545 // or itself if it is the one we are looking for.
2546 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseTransform* phase) {
2547 Node* n = *np;
2548 assert(n->is_ClearArray(), "sanity");
2549 intptr_t offset;
2550 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
2551 // This method is called only before Allocate nodes are expanded during
2552 // macro nodes expansion. Before that ClearArray nodes are only generated
2553 // in LibraryCallKit::generate_arraycopy() which follows allocations.
2554 assert(alloc != NULL, "should have allocation");
2555 if (alloc->_idx == instance_id) {
2556 // Can not bypass initialization of the instance we are looking for.
2557 return false;
2558 }
2559 // Otherwise skip it.
2560 InitializeNode* init = alloc->initialization();
2561 if (init != NULL)
2562 *np = init->in(TypeFunc::Memory);
2563 else
2564 *np = alloc->in(TypeFunc::Memory);
2565 return true;
2566 }
2568 //----------------------------clear_memory-------------------------------------
2569 // Generate code to initialize object storage to zero.
2570 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2571 intptr_t start_offset,
2572 Node* end_offset,
2573 PhaseGVN* phase) {
2574 Compile* C = phase->C;
2575 intptr_t offset = start_offset;
2577 int unit = BytesPerLong;
2578 if ((offset % unit) != 0) {
2579 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(offset));
2580 adr = phase->transform(adr);
2581 const TypePtr* atp = TypeRawPtr::BOTTOM;
2582 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2583 mem = phase->transform(mem);
2584 offset += BytesPerInt;
2585 }
2586 assert((offset % unit) == 0, "");
2588 // Initialize the remaining stuff, if any, with a ClearArray.
2589 return clear_memory(ctl, mem, dest, phase->MakeConX(offset), end_offset, phase);
2590 }
2592 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2593 Node* start_offset,
2594 Node* end_offset,
2595 PhaseGVN* phase) {
2596 if (start_offset == end_offset) {
2597 // nothing to do
2598 return mem;
2599 }
2601 Compile* C = phase->C;
2602 int unit = BytesPerLong;
2603 Node* zbase = start_offset;
2604 Node* zend = end_offset;
2606 // Scale to the unit required by the CPU:
2607 if (!Matcher::init_array_count_is_in_bytes) {
2608 Node* shift = phase->intcon(exact_log2(unit));
2609 zbase = phase->transform( new(C,3) URShiftXNode(zbase, shift) );
2610 zend = phase->transform( new(C,3) URShiftXNode(zend, shift) );
2611 }
2613 Node* zsize = phase->transform( new(C,3) SubXNode(zend, zbase) );
2614 Node* zinit = phase->zerocon((unit == BytesPerLong) ? T_LONG : T_INT);
2616 // Bulk clear double-words
2617 Node* adr = phase->transform( new(C,4) AddPNode(dest, dest, start_offset) );
2618 mem = new (C, 4) ClearArrayNode(ctl, mem, zsize, adr);
2619 return phase->transform(mem);
2620 }
2622 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
2623 intptr_t start_offset,
2624 intptr_t end_offset,
2625 PhaseGVN* phase) {
2626 if (start_offset == end_offset) {
2627 // nothing to do
2628 return mem;
2629 }
2631 Compile* C = phase->C;
2632 assert((end_offset % BytesPerInt) == 0, "odd end offset");
2633 intptr_t done_offset = end_offset;
2634 if ((done_offset % BytesPerLong) != 0) {
2635 done_offset -= BytesPerInt;
2636 }
2637 if (done_offset > start_offset) {
2638 mem = clear_memory(ctl, mem, dest,
2639 start_offset, phase->MakeConX(done_offset), phase);
2640 }
2641 if (done_offset < end_offset) { // emit the final 32-bit store
2642 Node* adr = new (C, 4) AddPNode(dest, dest, phase->MakeConX(done_offset));
2643 adr = phase->transform(adr);
2644 const TypePtr* atp = TypeRawPtr::BOTTOM;
2645 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT);
2646 mem = phase->transform(mem);
2647 done_offset += BytesPerInt;
2648 }
2649 assert(done_offset == end_offset, "");
2650 return mem;
2651 }
2653 //=============================================================================
2654 // Do not match memory edge.
2655 uint StrIntrinsicNode::match_edge(uint idx) const {
2656 return idx == 2 || idx == 3;
2657 }
2659 //------------------------------Ideal------------------------------------------
2660 // Return a node which is more "ideal" than the current node. Strip out
2661 // control copies
2662 Node *StrIntrinsicNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2663 if (remove_dead_region(phase, can_reshape)) return this;
2664 // Don't bother trying to transform a dead node
2665 if (in(0) && in(0)->is_top()) return NULL;
2667 if (can_reshape) {
2668 Node* mem = phase->transform(in(MemNode::Memory));
2669 // If transformed to a MergeMem, get the desired slice
2670 uint alias_idx = phase->C->get_alias_index(adr_type());
2671 mem = mem->is_MergeMem() ? mem->as_MergeMem()->memory_at(alias_idx) : mem;
2672 if (mem != in(MemNode::Memory)) {
2673 set_req(MemNode::Memory, mem);
2674 return this;
2675 }
2676 }
2677 return NULL;
2678 }
2680 //------------------------------Value------------------------------------------
2681 const Type *StrIntrinsicNode::Value( PhaseTransform *phase ) const {
2682 if (in(0) && phase->type(in(0)) == Type::TOP) return Type::TOP;
2683 return bottom_type();
2684 }
2686 //=============================================================================
2687 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
2688 : MultiNode(TypeFunc::Parms + (precedent == NULL? 0: 1)),
2689 _adr_type(C->get_adr_type(alias_idx))
2690 {
2691 init_class_id(Class_MemBar);
2692 Node* top = C->top();
2693 init_req(TypeFunc::I_O,top);
2694 init_req(TypeFunc::FramePtr,top);
2695 init_req(TypeFunc::ReturnAdr,top);
2696 if (precedent != NULL)
2697 init_req(TypeFunc::Parms, precedent);
2698 }
2700 //------------------------------cmp--------------------------------------------
2701 uint MemBarNode::hash() const { return NO_HASH; }
2702 uint MemBarNode::cmp( const Node &n ) const {
2703 return (&n == this); // Always fail except on self
2704 }
2706 //------------------------------make-------------------------------------------
2707 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
2708 int len = Precedent + (pn == NULL? 0: 1);
2709 switch (opcode) {
2710 case Op_MemBarAcquire: return new(C, len) MemBarAcquireNode(C, atp, pn);
2711 case Op_MemBarRelease: return new(C, len) MemBarReleaseNode(C, atp, pn);
2712 case Op_MemBarAcquireLock: return new(C, len) MemBarAcquireLockNode(C, atp, pn);
2713 case Op_MemBarReleaseLock: return new(C, len) MemBarReleaseLockNode(C, atp, pn);
2714 case Op_MemBarVolatile: return new(C, len) MemBarVolatileNode(C, atp, pn);
2715 case Op_MemBarCPUOrder: return new(C, len) MemBarCPUOrderNode(C, atp, pn);
2716 case Op_Initialize: return new(C, len) InitializeNode(C, atp, pn);
2717 default: ShouldNotReachHere(); return NULL;
2718 }
2719 }
2721 //------------------------------Ideal------------------------------------------
2722 // Return a node which is more "ideal" than the current node. Strip out
2723 // control copies
2724 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2725 if (remove_dead_region(phase, can_reshape)) return this;
2726 // Don't bother trying to transform a dead node
2727 if (in(0) && in(0)->is_top()) return NULL;
2729 // Eliminate volatile MemBars for scalar replaced objects.
2730 if (can_reshape && req() == (Precedent+1) &&
2731 (Opcode() == Op_MemBarAcquire || Opcode() == Op_MemBarVolatile)) {
2732 // Volatile field loads and stores.
2733 Node* my_mem = in(MemBarNode::Precedent);
2734 if (my_mem != NULL && my_mem->is_Mem()) {
2735 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
2736 // Check for scalar replaced object reference.
2737 if( t_oop != NULL && t_oop->is_known_instance_field() &&
2738 t_oop->offset() != Type::OffsetBot &&
2739 t_oop->offset() != Type::OffsetTop) {
2740 // Replace MemBar projections by its inputs.
2741 PhaseIterGVN* igvn = phase->is_IterGVN();
2742 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
2743 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
2744 // Must return either the original node (now dead) or a new node
2745 // (Do not return a top here, since that would break the uniqueness of top.)
2746 return new (phase->C, 1) ConINode(TypeInt::ZERO);
2747 }
2748 }
2749 }
2750 return NULL;
2751 }
2753 //------------------------------Value------------------------------------------
2754 const Type *MemBarNode::Value( PhaseTransform *phase ) const {
2755 if( !in(0) ) return Type::TOP;
2756 if( phase->type(in(0)) == Type::TOP )
2757 return Type::TOP;
2758 return TypeTuple::MEMBAR;
2759 }
2761 //------------------------------match------------------------------------------
2762 // Construct projections for memory.
2763 Node *MemBarNode::match( const ProjNode *proj, const Matcher *m ) {
2764 switch (proj->_con) {
2765 case TypeFunc::Control:
2766 case TypeFunc::Memory:
2767 return new (m->C, 1) MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
2768 }
2769 ShouldNotReachHere();
2770 return NULL;
2771 }
2773 //===========================InitializeNode====================================
2774 // SUMMARY:
2775 // This node acts as a memory barrier on raw memory, after some raw stores.
2776 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
2777 // The Initialize can 'capture' suitably constrained stores as raw inits.
2778 // It can coalesce related raw stores into larger units (called 'tiles').
2779 // It can avoid zeroing new storage for memory units which have raw inits.
2780 // At macro-expansion, it is marked 'complete', and does not optimize further.
2781 //
2782 // EXAMPLE:
2783 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
2784 // ctl = incoming control; mem* = incoming memory
2785 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
2786 // First allocate uninitialized memory and fill in the header:
2787 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
2788 // ctl := alloc.Control; mem* := alloc.Memory*
2789 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
2790 // Then initialize to zero the non-header parts of the raw memory block:
2791 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
2792 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
2793 // After the initialize node executes, the object is ready for service:
2794 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
2795 // Suppose its body is immediately initialized as {1,2}:
2796 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
2797 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
2798 // mem.SLICE(#short[*]) := store2
2799 //
2800 // DETAILS:
2801 // An InitializeNode collects and isolates object initialization after
2802 // an AllocateNode and before the next possible safepoint. As a
2803 // memory barrier (MemBarNode), it keeps critical stores from drifting
2804 // down past any safepoint or any publication of the allocation.
2805 // Before this barrier, a newly-allocated object may have uninitialized bits.
2806 // After this barrier, it may be treated as a real oop, and GC is allowed.
2807 //
2808 // The semantics of the InitializeNode include an implicit zeroing of
2809 // the new object from object header to the end of the object.
2810 // (The object header and end are determined by the AllocateNode.)
2811 //
2812 // Certain stores may be added as direct inputs to the InitializeNode.
2813 // These stores must update raw memory, and they must be to addresses
2814 // derived from the raw address produced by AllocateNode, and with
2815 // a constant offset. They must be ordered by increasing offset.
2816 // The first one is at in(RawStores), the last at in(req()-1).
2817 // Unlike most memory operations, they are not linked in a chain,
2818 // but are displayed in parallel as users of the rawmem output of
2819 // the allocation.
2820 //
2821 // (See comments in InitializeNode::capture_store, which continue
2822 // the example given above.)
2823 //
2824 // When the associated Allocate is macro-expanded, the InitializeNode
2825 // may be rewritten to optimize collected stores. A ClearArrayNode
2826 // may also be created at that point to represent any required zeroing.
2827 // The InitializeNode is then marked 'complete', prohibiting further
2828 // capturing of nearby memory operations.
2829 //
2830 // During macro-expansion, all captured initializations which store
2831 // constant values of 32 bits or smaller are coalesced (if advantageous)
2832 // into larger 'tiles' 32 or 64 bits. This allows an object to be
2833 // initialized in fewer memory operations. Memory words which are
2834 // covered by neither tiles nor non-constant stores are pre-zeroed
2835 // by explicit stores of zero. (The code shape happens to do all
2836 // zeroing first, then all other stores, with both sequences occurring
2837 // in order of ascending offsets.)
2838 //
2839 // Alternatively, code may be inserted between an AllocateNode and its
2840 // InitializeNode, to perform arbitrary initialization of the new object.
2841 // E.g., the object copying intrinsics insert complex data transfers here.
2842 // The initialization must then be marked as 'complete' disable the
2843 // built-in zeroing semantics and the collection of initializing stores.
2844 //
2845 // While an InitializeNode is incomplete, reads from the memory state
2846 // produced by it are optimizable if they match the control edge and
2847 // new oop address associated with the allocation/initialization.
2848 // They return a stored value (if the offset matches) or else zero.
2849 // A write to the memory state, if it matches control and address,
2850 // and if it is to a constant offset, may be 'captured' by the
2851 // InitializeNode. It is cloned as a raw memory operation and rewired
2852 // inside the initialization, to the raw oop produced by the allocation.
2853 // Operations on addresses which are provably distinct (e.g., to
2854 // other AllocateNodes) are allowed to bypass the initialization.
2855 //
2856 // The effect of all this is to consolidate object initialization
2857 // (both arrays and non-arrays, both piecewise and bulk) into a
2858 // single location, where it can be optimized as a unit.
2859 //
2860 // Only stores with an offset less than TrackedInitializationLimit words
2861 // will be considered for capture by an InitializeNode. This puts a
2862 // reasonable limit on the complexity of optimized initializations.
2864 //---------------------------InitializeNode------------------------------------
2865 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
2866 : _is_complete(Incomplete),
2867 MemBarNode(C, adr_type, rawoop)
2868 {
2869 init_class_id(Class_Initialize);
2871 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
2872 assert(in(RawAddress) == rawoop, "proper init");
2873 // Note: allocation() can be NULL, for secondary initialization barriers
2874 }
2876 // Since this node is not matched, it will be processed by the
2877 // register allocator. Declare that there are no constraints
2878 // on the allocation of the RawAddress edge.
2879 const RegMask &InitializeNode::in_RegMask(uint idx) const {
2880 // This edge should be set to top, by the set_complete. But be conservative.
2881 if (idx == InitializeNode::RawAddress)
2882 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
2883 return RegMask::Empty;
2884 }
2886 Node* InitializeNode::memory(uint alias_idx) {
2887 Node* mem = in(Memory);
2888 if (mem->is_MergeMem()) {
2889 return mem->as_MergeMem()->memory_at(alias_idx);
2890 } else {
2891 // incoming raw memory is not split
2892 return mem;
2893 }
2894 }
2896 bool InitializeNode::is_non_zero() {
2897 if (is_complete()) return false;
2898 remove_extra_zeroes();
2899 return (req() > RawStores);
2900 }
2902 void InitializeNode::set_complete(PhaseGVN* phase) {
2903 assert(!is_complete(), "caller responsibility");
2904 _is_complete = Complete;
2906 // After this node is complete, it contains a bunch of
2907 // raw-memory initializations. There is no need for
2908 // it to have anything to do with non-raw memory effects.
2909 // Therefore, tell all non-raw users to re-optimize themselves,
2910 // after skipping the memory effects of this initialization.
2911 PhaseIterGVN* igvn = phase->is_IterGVN();
2912 if (igvn) igvn->add_users_to_worklist(this);
2913 }
2915 // convenience function
2916 // return false if the init contains any stores already
2917 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
2918 InitializeNode* init = initialization();
2919 if (init == NULL || init->is_complete()) return false;
2920 init->remove_extra_zeroes();
2921 // for now, if this allocation has already collected any inits, bail:
2922 if (init->is_non_zero()) return false;
2923 init->set_complete(phase);
2924 return true;
2925 }
2927 void InitializeNode::remove_extra_zeroes() {
2928 if (req() == RawStores) return;
2929 Node* zmem = zero_memory();
2930 uint fill = RawStores;
2931 for (uint i = fill; i < req(); i++) {
2932 Node* n = in(i);
2933 if (n->is_top() || n == zmem) continue; // skip
2934 if (fill < i) set_req(fill, n); // compact
2935 ++fill;
2936 }
2937 // delete any empty spaces created:
2938 while (fill < req()) {
2939 del_req(fill);
2940 }
2941 }
2943 // Helper for remembering which stores go with which offsets.
2944 intptr_t InitializeNode::get_store_offset(Node* st, PhaseTransform* phase) {
2945 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
2946 intptr_t offset = -1;
2947 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
2948 phase, offset);
2949 if (base == NULL) return -1; // something is dead,
2950 if (offset < 0) return -1; // dead, dead
2951 return offset;
2952 }
2954 // Helper for proving that an initialization expression is
2955 // "simple enough" to be folded into an object initialization.
2956 // Attempts to prove that a store's initial value 'n' can be captured
2957 // within the initialization without creating a vicious cycle, such as:
2958 // { Foo p = new Foo(); p.next = p; }
2959 // True for constants and parameters and small combinations thereof.
2960 bool InitializeNode::detect_init_independence(Node* n,
2961 bool st_is_pinned,
2962 int& count) {
2963 if (n == NULL) return true; // (can this really happen?)
2964 if (n->is_Proj()) n = n->in(0);
2965 if (n == this) return false; // found a cycle
2966 if (n->is_Con()) return true;
2967 if (n->is_Start()) return true; // params, etc., are OK
2968 if (n->is_Root()) return true; // even better
2970 Node* ctl = n->in(0);
2971 if (ctl != NULL && !ctl->is_top()) {
2972 if (ctl->is_Proj()) ctl = ctl->in(0);
2973 if (ctl == this) return false;
2975 // If we already know that the enclosing memory op is pinned right after
2976 // the init, then any control flow that the store has picked up
2977 // must have preceded the init, or else be equal to the init.
2978 // Even after loop optimizations (which might change control edges)
2979 // a store is never pinned *before* the availability of its inputs.
2980 if (!MemNode::all_controls_dominate(n, this))
2981 return false; // failed to prove a good control
2983 }
2985 // Check data edges for possible dependencies on 'this'.
2986 if ((count += 1) > 20) return false; // complexity limit
2987 for (uint i = 1; i < n->req(); i++) {
2988 Node* m = n->in(i);
2989 if (m == NULL || m == n || m->is_top()) continue;
2990 uint first_i = n->find_edge(m);
2991 if (i != first_i) continue; // process duplicate edge just once
2992 if (!detect_init_independence(m, st_is_pinned, count)) {
2993 return false;
2994 }
2995 }
2997 return true;
2998 }
3000 // Here are all the checks a Store must pass before it can be moved into
3001 // an initialization. Returns zero if a check fails.
3002 // On success, returns the (constant) offset to which the store applies,
3003 // within the initialized memory.
3004 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseTransform* phase) {
3005 const int FAIL = 0;
3006 if (st->req() != MemNode::ValueIn + 1)
3007 return FAIL; // an inscrutable StoreNode (card mark?)
3008 Node* ctl = st->in(MemNode::Control);
3009 if (!(ctl != NULL && ctl->is_Proj() && ctl->in(0) == this))
3010 return FAIL; // must be unconditional after the initialization
3011 Node* mem = st->in(MemNode::Memory);
3012 if (!(mem->is_Proj() && mem->in(0) == this))
3013 return FAIL; // must not be preceded by other stores
3014 Node* adr = st->in(MemNode::Address);
3015 intptr_t offset;
3016 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
3017 if (alloc == NULL)
3018 return FAIL; // inscrutable address
3019 if (alloc != allocation())
3020 return FAIL; // wrong allocation! (store needs to float up)
3021 Node* val = st->in(MemNode::ValueIn);
3022 int complexity_count = 0;
3023 if (!detect_init_independence(val, true, complexity_count))
3024 return FAIL; // stored value must be 'simple enough'
3026 return offset; // success
3027 }
3029 // Find the captured store in(i) which corresponds to the range
3030 // [start..start+size) in the initialized object.
3031 // If there is one, return its index i. If there isn't, return the
3032 // negative of the index where it should be inserted.
3033 // Return 0 if the queried range overlaps an initialization boundary
3034 // or if dead code is encountered.
3035 // If size_in_bytes is zero, do not bother with overlap checks.
3036 int InitializeNode::captured_store_insertion_point(intptr_t start,
3037 int size_in_bytes,
3038 PhaseTransform* phase) {
3039 const int FAIL = 0, MAX_STORE = BytesPerLong;
3041 if (is_complete())
3042 return FAIL; // arraycopy got here first; punt
3044 assert(allocation() != NULL, "must be present");
3046 // no negatives, no header fields:
3047 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
3049 // after a certain size, we bail out on tracking all the stores:
3050 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3051 if (start >= ti_limit) return FAIL;
3053 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
3054 if (i >= limit) return -(int)i; // not found; here is where to put it
3056 Node* st = in(i);
3057 intptr_t st_off = get_store_offset(st, phase);
3058 if (st_off < 0) {
3059 if (st != zero_memory()) {
3060 return FAIL; // bail out if there is dead garbage
3061 }
3062 } else if (st_off > start) {
3063 // ...we are done, since stores are ordered
3064 if (st_off < start + size_in_bytes) {
3065 return FAIL; // the next store overlaps
3066 }
3067 return -(int)i; // not found; here is where to put it
3068 } else if (st_off < start) {
3069 if (size_in_bytes != 0 &&
3070 start < st_off + MAX_STORE &&
3071 start < st_off + st->as_Store()->memory_size()) {
3072 return FAIL; // the previous store overlaps
3073 }
3074 } else {
3075 if (size_in_bytes != 0 &&
3076 st->as_Store()->memory_size() != size_in_bytes) {
3077 return FAIL; // mismatched store size
3078 }
3079 return i;
3080 }
3082 ++i;
3083 }
3084 }
3086 // Look for a captured store which initializes at the offset 'start'
3087 // with the given size. If there is no such store, and no other
3088 // initialization interferes, then return zero_memory (the memory
3089 // projection of the AllocateNode).
3090 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
3091 PhaseTransform* phase) {
3092 assert(stores_are_sane(phase), "");
3093 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3094 if (i == 0) {
3095 return NULL; // something is dead
3096 } else if (i < 0) {
3097 return zero_memory(); // just primordial zero bits here
3098 } else {
3099 Node* st = in(i); // here is the store at this position
3100 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
3101 return st;
3102 }
3103 }
3105 // Create, as a raw pointer, an address within my new object at 'offset'.
3106 Node* InitializeNode::make_raw_address(intptr_t offset,
3107 PhaseTransform* phase) {
3108 Node* addr = in(RawAddress);
3109 if (offset != 0) {
3110 Compile* C = phase->C;
3111 addr = phase->transform( new (C, 4) AddPNode(C->top(), addr,
3112 phase->MakeConX(offset)) );
3113 }
3114 return addr;
3115 }
3117 // Clone the given store, converting it into a raw store
3118 // initializing a field or element of my new object.
3119 // Caller is responsible for retiring the original store,
3120 // with subsume_node or the like.
3121 //
3122 // From the example above InitializeNode::InitializeNode,
3123 // here are the old stores to be captured:
3124 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
3125 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
3126 //
3127 // Here is the changed code; note the extra edges on init:
3128 // alloc = (Allocate ...)
3129 // rawoop = alloc.RawAddress
3130 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
3131 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
3132 // init = (Initialize alloc.Control alloc.Memory rawoop
3133 // rawstore1 rawstore2)
3134 //
3135 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
3136 PhaseTransform* phase) {
3137 assert(stores_are_sane(phase), "");
3139 if (start < 0) return NULL;
3140 assert(can_capture_store(st, phase) == start, "sanity");
3142 Compile* C = phase->C;
3143 int size_in_bytes = st->memory_size();
3144 int i = captured_store_insertion_point(start, size_in_bytes, phase);
3145 if (i == 0) return NULL; // bail out
3146 Node* prev_mem = NULL; // raw memory for the captured store
3147 if (i > 0) {
3148 prev_mem = in(i); // there is a pre-existing store under this one
3149 set_req(i, C->top()); // temporarily disconnect it
3150 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
3151 } else {
3152 i = -i; // no pre-existing store
3153 prev_mem = zero_memory(); // a slice of the newly allocated object
3154 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
3155 set_req(--i, C->top()); // reuse this edge; it has been folded away
3156 else
3157 ins_req(i, C->top()); // build a new edge
3158 }
3159 Node* new_st = st->clone();
3160 new_st->set_req(MemNode::Control, in(Control));
3161 new_st->set_req(MemNode::Memory, prev_mem);
3162 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
3163 new_st = phase->transform(new_st);
3165 // At this point, new_st might have swallowed a pre-existing store
3166 // at the same offset, or perhaps new_st might have disappeared,
3167 // if it redundantly stored the same value (or zero to fresh memory).
3169 // In any case, wire it in:
3170 set_req(i, new_st);
3172 // The caller may now kill the old guy.
3173 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
3174 assert(check_st == new_st || check_st == NULL, "must be findable");
3175 assert(!is_complete(), "");
3176 return new_st;
3177 }
3179 static bool store_constant(jlong* tiles, int num_tiles,
3180 intptr_t st_off, int st_size,
3181 jlong con) {
3182 if ((st_off & (st_size-1)) != 0)
3183 return false; // strange store offset (assume size==2**N)
3184 address addr = (address)tiles + st_off;
3185 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
3186 switch (st_size) {
3187 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
3188 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
3189 case sizeof(jint): *(jint*) addr = (jint) con; break;
3190 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
3191 default: return false; // strange store size (detect size!=2**N here)
3192 }
3193 return true; // return success to caller
3194 }
3196 // Coalesce subword constants into int constants and possibly
3197 // into long constants. The goal, if the CPU permits,
3198 // is to initialize the object with a small number of 64-bit tiles.
3199 // Also, convert floating-point constants to bit patterns.
3200 // Non-constants are not relevant to this pass.
3201 //
3202 // In terms of the running example on InitializeNode::InitializeNode
3203 // and InitializeNode::capture_store, here is the transformation
3204 // of rawstore1 and rawstore2 into rawstore12:
3205 // alloc = (Allocate ...)
3206 // rawoop = alloc.RawAddress
3207 // tile12 = 0x00010002
3208 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
3209 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
3210 //
3211 void
3212 InitializeNode::coalesce_subword_stores(intptr_t header_size,
3213 Node* size_in_bytes,
3214 PhaseGVN* phase) {
3215 Compile* C = phase->C;
3217 assert(stores_are_sane(phase), "");
3218 // Note: After this pass, they are not completely sane,
3219 // since there may be some overlaps.
3221 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
3223 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
3224 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
3225 size_limit = MIN2(size_limit, ti_limit);
3226 size_limit = align_size_up(size_limit, BytesPerLong);
3227 int num_tiles = size_limit / BytesPerLong;
3229 // allocate space for the tile map:
3230 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
3231 jlong tiles_buf[small_len];
3232 Node* nodes_buf[small_len];
3233 jlong inits_buf[small_len];
3234 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
3235 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3236 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
3237 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
3238 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
3239 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
3240 // tiles: exact bitwise model of all primitive constants
3241 // nodes: last constant-storing node subsumed into the tiles model
3242 // inits: which bytes (in each tile) are touched by any initializations
3244 //// Pass A: Fill in the tile model with any relevant stores.
3246 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
3247 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
3248 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
3249 Node* zmem = zero_memory(); // initially zero memory state
3250 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3251 Node* st = in(i);
3252 intptr_t st_off = get_store_offset(st, phase);
3254 // Figure out the store's offset and constant value:
3255 if (st_off < header_size) continue; //skip (ignore header)
3256 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
3257 int st_size = st->as_Store()->memory_size();
3258 if (st_off + st_size > size_limit) break;
3260 // Record which bytes are touched, whether by constant or not.
3261 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
3262 continue; // skip (strange store size)
3264 const Type* val = phase->type(st->in(MemNode::ValueIn));
3265 if (!val->singleton()) continue; //skip (non-con store)
3266 BasicType type = val->basic_type();
3268 jlong con = 0;
3269 switch (type) {
3270 case T_INT: con = val->is_int()->get_con(); break;
3271 case T_LONG: con = val->is_long()->get_con(); break;
3272 case T_FLOAT: con = jint_cast(val->getf()); break;
3273 case T_DOUBLE: con = jlong_cast(val->getd()); break;
3274 default: continue; //skip (odd store type)
3275 }
3277 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
3278 st->Opcode() == Op_StoreL) {
3279 continue; // This StoreL is already optimal.
3280 }
3282 // Store down the constant.
3283 store_constant(tiles, num_tiles, st_off, st_size, con);
3285 intptr_t j = st_off >> LogBytesPerLong;
3287 if (type == T_INT && st_size == BytesPerInt
3288 && (st_off & BytesPerInt) == BytesPerInt) {
3289 jlong lcon = tiles[j];
3290 if (!Matcher::isSimpleConstant64(lcon) &&
3291 st->Opcode() == Op_StoreI) {
3292 // This StoreI is already optimal by itself.
3293 jint* intcon = (jint*) &tiles[j];
3294 intcon[1] = 0; // undo the store_constant()
3296 // If the previous store is also optimal by itself, back up and
3297 // undo the action of the previous loop iteration... if we can.
3298 // But if we can't, just let the previous half take care of itself.
3299 st = nodes[j];
3300 st_off -= BytesPerInt;
3301 con = intcon[0];
3302 if (con != 0 && st != NULL && st->Opcode() == Op_StoreI) {
3303 assert(st_off >= header_size, "still ignoring header");
3304 assert(get_store_offset(st, phase) == st_off, "must be");
3305 assert(in(i-1) == zmem, "must be");
3306 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
3307 assert(con == tcon->is_int()->get_con(), "must be");
3308 // Undo the effects of the previous loop trip, which swallowed st:
3309 intcon[0] = 0; // undo store_constant()
3310 set_req(i-1, st); // undo set_req(i, zmem)
3311 nodes[j] = NULL; // undo nodes[j] = st
3312 --old_subword; // undo ++old_subword
3313 }
3314 continue; // This StoreI is already optimal.
3315 }
3316 }
3318 // This store is not needed.
3319 set_req(i, zmem);
3320 nodes[j] = st; // record for the moment
3321 if (st_size < BytesPerLong) // something has changed
3322 ++old_subword; // includes int/float, but who's counting...
3323 else ++old_long;
3324 }
3326 if ((old_subword + old_long) == 0)
3327 return; // nothing more to do
3329 //// Pass B: Convert any non-zero tiles into optimal constant stores.
3330 // Be sure to insert them before overlapping non-constant stores.
3331 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
3332 for (int j = 0; j < num_tiles; j++) {
3333 jlong con = tiles[j];
3334 jlong init = inits[j];
3335 if (con == 0) continue;
3336 jint con0, con1; // split the constant, address-wise
3337 jint init0, init1; // split the init map, address-wise
3338 { union { jlong con; jint intcon[2]; } u;
3339 u.con = con;
3340 con0 = u.intcon[0];
3341 con1 = u.intcon[1];
3342 u.con = init;
3343 init0 = u.intcon[0];
3344 init1 = u.intcon[1];
3345 }
3347 Node* old = nodes[j];
3348 assert(old != NULL, "need the prior store");
3349 intptr_t offset = (j * BytesPerLong);
3351 bool split = !Matcher::isSimpleConstant64(con);
3353 if (offset < header_size) {
3354 assert(offset + BytesPerInt >= header_size, "second int counts");
3355 assert(*(jint*)&tiles[j] == 0, "junk in header");
3356 split = true; // only the second word counts
3357 // Example: int a[] = { 42 ... }
3358 } else if (con0 == 0 && init0 == -1) {
3359 split = true; // first word is covered by full inits
3360 // Example: int a[] = { ... foo(), 42 ... }
3361 } else if (con1 == 0 && init1 == -1) {
3362 split = true; // second word is covered by full inits
3363 // Example: int a[] = { ... 42, foo() ... }
3364 }
3366 // Here's a case where init0 is neither 0 nor -1:
3367 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
3368 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
3369 // In this case the tile is not split; it is (jlong)42.
3370 // The big tile is stored down, and then the foo() value is inserted.
3371 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
3373 Node* ctl = old->in(MemNode::Control);
3374 Node* adr = make_raw_address(offset, phase);
3375 const TypePtr* atp = TypeRawPtr::BOTTOM;
3377 // One or two coalesced stores to plop down.
3378 Node* st[2];
3379 intptr_t off[2];
3380 int nst = 0;
3381 if (!split) {
3382 ++new_long;
3383 off[nst] = offset;
3384 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3385 phase->longcon(con), T_LONG);
3386 } else {
3387 // Omit either if it is a zero.
3388 if (con0 != 0) {
3389 ++new_int;
3390 off[nst] = offset;
3391 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3392 phase->intcon(con0), T_INT);
3393 }
3394 if (con1 != 0) {
3395 ++new_int;
3396 offset += BytesPerInt;
3397 adr = make_raw_address(offset, phase);
3398 off[nst] = offset;
3399 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
3400 phase->intcon(con1), T_INT);
3401 }
3402 }
3404 // Insert second store first, then the first before the second.
3405 // Insert each one just before any overlapping non-constant stores.
3406 while (nst > 0) {
3407 Node* st1 = st[--nst];
3408 C->copy_node_notes_to(st1, old);
3409 st1 = phase->transform(st1);
3410 offset = off[nst];
3411 assert(offset >= header_size, "do not smash header");
3412 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
3413 guarantee(ins_idx != 0, "must re-insert constant store");
3414 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
3415 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
3416 set_req(--ins_idx, st1);
3417 else
3418 ins_req(ins_idx, st1);
3419 }
3420 }
3422 if (PrintCompilation && WizardMode)
3423 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
3424 old_subword, old_long, new_int, new_long);
3425 if (C->log() != NULL)
3426 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
3427 old_subword, old_long, new_int, new_long);
3429 // Clean up any remaining occurrences of zmem:
3430 remove_extra_zeroes();
3431 }
3433 // Explore forward from in(start) to find the first fully initialized
3434 // word, and return its offset. Skip groups of subword stores which
3435 // together initialize full words. If in(start) is itself part of a
3436 // fully initialized word, return the offset of in(start). If there
3437 // are no following full-word stores, or if something is fishy, return
3438 // a negative value.
3439 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
3440 int int_map = 0;
3441 intptr_t int_map_off = 0;
3442 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
3444 for (uint i = start, limit = req(); i < limit; i++) {
3445 Node* st = in(i);
3447 intptr_t st_off = get_store_offset(st, phase);
3448 if (st_off < 0) break; // return conservative answer
3450 int st_size = st->as_Store()->memory_size();
3451 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
3452 return st_off; // we found a complete word init
3453 }
3455 // update the map:
3457 intptr_t this_int_off = align_size_down(st_off, BytesPerInt);
3458 if (this_int_off != int_map_off) {
3459 // reset the map:
3460 int_map = 0;
3461 int_map_off = this_int_off;
3462 }
3464 int subword_off = st_off - this_int_off;
3465 int_map |= right_n_bits(st_size) << subword_off;
3466 if ((int_map & FULL_MAP) == FULL_MAP) {
3467 return this_int_off; // we found a complete word init
3468 }
3470 // Did this store hit or cross the word boundary?
3471 intptr_t next_int_off = align_size_down(st_off + st_size, BytesPerInt);
3472 if (next_int_off == this_int_off + BytesPerInt) {
3473 // We passed the current int, without fully initializing it.
3474 int_map_off = next_int_off;
3475 int_map >>= BytesPerInt;
3476 } else if (next_int_off > this_int_off + BytesPerInt) {
3477 // We passed the current and next int.
3478 return this_int_off + BytesPerInt;
3479 }
3480 }
3482 return -1;
3483 }
3486 // Called when the associated AllocateNode is expanded into CFG.
3487 // At this point, we may perform additional optimizations.
3488 // Linearize the stores by ascending offset, to make memory
3489 // activity as coherent as possible.
3490 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
3491 intptr_t header_size,
3492 Node* size_in_bytes,
3493 PhaseGVN* phase) {
3494 assert(!is_complete(), "not already complete");
3495 assert(stores_are_sane(phase), "");
3496 assert(allocation() != NULL, "must be present");
3498 remove_extra_zeroes();
3500 if (ReduceFieldZeroing || ReduceBulkZeroing)
3501 // reduce instruction count for common initialization patterns
3502 coalesce_subword_stores(header_size, size_in_bytes, phase);
3504 Node* zmem = zero_memory(); // initially zero memory state
3505 Node* inits = zmem; // accumulating a linearized chain of inits
3506 #ifdef ASSERT
3507 intptr_t first_offset = allocation()->minimum_header_size();
3508 intptr_t last_init_off = first_offset; // previous init offset
3509 intptr_t last_init_end = first_offset; // previous init offset+size
3510 intptr_t last_tile_end = first_offset; // previous tile offset+size
3511 #endif
3512 intptr_t zeroes_done = header_size;
3514 bool do_zeroing = true; // we might give up if inits are very sparse
3515 int big_init_gaps = 0; // how many large gaps have we seen?
3517 if (ZeroTLAB) do_zeroing = false;
3518 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
3520 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
3521 Node* st = in(i);
3522 intptr_t st_off = get_store_offset(st, phase);
3523 if (st_off < 0)
3524 break; // unknown junk in the inits
3525 if (st->in(MemNode::Memory) != zmem)
3526 break; // complicated store chains somehow in list
3528 int st_size = st->as_Store()->memory_size();
3529 intptr_t next_init_off = st_off + st_size;
3531 if (do_zeroing && zeroes_done < next_init_off) {
3532 // See if this store needs a zero before it or under it.
3533 intptr_t zeroes_needed = st_off;
3535 if (st_size < BytesPerInt) {
3536 // Look for subword stores which only partially initialize words.
3537 // If we find some, we must lay down some word-level zeroes first,
3538 // underneath the subword stores.
3539 //
3540 // Examples:
3541 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
3542 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
3543 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
3544 //
3545 // Note: coalesce_subword_stores may have already done this,
3546 // if it was prompted by constant non-zero subword initializers.
3547 // But this case can still arise with non-constant stores.
3549 intptr_t next_full_store = find_next_fullword_store(i, phase);
3551 // In the examples above:
3552 // in(i) p q r s x y z
3553 // st_off 12 13 14 15 12 13 14
3554 // st_size 1 1 1 1 1 1 1
3555 // next_full_s. 12 16 16 16 16 16 16
3556 // z's_done 12 16 16 16 12 16 12
3557 // z's_needed 12 16 16 16 16 16 16
3558 // zsize 0 0 0 0 4 0 4
3559 if (next_full_store < 0) {
3560 // Conservative tack: Zero to end of current word.
3561 zeroes_needed = align_size_up(zeroes_needed, BytesPerInt);
3562 } else {
3563 // Zero to beginning of next fully initialized word.
3564 // Or, don't zero at all, if we are already in that word.
3565 assert(next_full_store >= zeroes_needed, "must go forward");
3566 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
3567 zeroes_needed = next_full_store;
3568 }
3569 }
3571 if (zeroes_needed > zeroes_done) {
3572 intptr_t zsize = zeroes_needed - zeroes_done;
3573 // Do some incremental zeroing on rawmem, in parallel with inits.
3574 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3575 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3576 zeroes_done, zeroes_needed,
3577 phase);
3578 zeroes_done = zeroes_needed;
3579 if (zsize > Matcher::init_array_short_size && ++big_init_gaps > 2)
3580 do_zeroing = false; // leave the hole, next time
3581 }
3582 }
3584 // Collect the store and move on:
3585 st->set_req(MemNode::Memory, inits);
3586 inits = st; // put it on the linearized chain
3587 set_req(i, zmem); // unhook from previous position
3589 if (zeroes_done == st_off)
3590 zeroes_done = next_init_off;
3592 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
3594 #ifdef ASSERT
3595 // Various order invariants. Weaker than stores_are_sane because
3596 // a large constant tile can be filled in by smaller non-constant stores.
3597 assert(st_off >= last_init_off, "inits do not reverse");
3598 last_init_off = st_off;
3599 const Type* val = NULL;
3600 if (st_size >= BytesPerInt &&
3601 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
3602 (int)val->basic_type() < (int)T_OBJECT) {
3603 assert(st_off >= last_tile_end, "tiles do not overlap");
3604 assert(st_off >= last_init_end, "tiles do not overwrite inits");
3605 last_tile_end = MAX2(last_tile_end, next_init_off);
3606 } else {
3607 intptr_t st_tile_end = align_size_up(next_init_off, BytesPerLong);
3608 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
3609 assert(st_off >= last_init_end, "inits do not overlap");
3610 last_init_end = next_init_off; // it's a non-tile
3611 }
3612 #endif //ASSERT
3613 }
3615 remove_extra_zeroes(); // clear out all the zmems left over
3616 add_req(inits);
3618 if (!ZeroTLAB) {
3619 // If anything remains to be zeroed, zero it all now.
3620 zeroes_done = align_size_down(zeroes_done, BytesPerInt);
3621 // if it is the last unused 4 bytes of an instance, forget about it
3622 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
3623 if (zeroes_done + BytesPerLong >= size_limit) {
3624 assert(allocation() != NULL, "");
3625 if (allocation()->Opcode() == Op_Allocate) {
3626 Node* klass_node = allocation()->in(AllocateNode::KlassNode);
3627 ciKlass* k = phase->type(klass_node)->is_klassptr()->klass();
3628 if (zeroes_done == k->layout_helper())
3629 zeroes_done = size_limit;
3630 }
3631 }
3632 if (zeroes_done < size_limit) {
3633 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
3634 zeroes_done, size_in_bytes, phase);
3635 }
3636 }
3638 set_complete(phase);
3639 return rawmem;
3640 }
3643 #ifdef ASSERT
3644 bool InitializeNode::stores_are_sane(PhaseTransform* phase) {
3645 if (is_complete())
3646 return true; // stores could be anything at this point
3647 assert(allocation() != NULL, "must be present");
3648 intptr_t last_off = allocation()->minimum_header_size();
3649 for (uint i = InitializeNode::RawStores; i < req(); i++) {
3650 Node* st = in(i);
3651 intptr_t st_off = get_store_offset(st, phase);
3652 if (st_off < 0) continue; // ignore dead garbage
3653 if (last_off > st_off) {
3654 tty->print_cr("*** bad store offset at %d: %d > %d", i, last_off, st_off);
3655 this->dump(2);
3656 assert(false, "ascending store offsets");
3657 return false;
3658 }
3659 last_off = st_off + st->as_Store()->memory_size();
3660 }
3661 return true;
3662 }
3663 #endif //ASSERT
3668 //============================MergeMemNode=====================================
3669 //
3670 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
3671 // contributing store or call operations. Each contributor provides the memory
3672 // state for a particular "alias type" (see Compile::alias_type). For example,
3673 // if a MergeMem has an input X for alias category #6, then any memory reference
3674 // to alias category #6 may use X as its memory state input, as an exact equivalent
3675 // to using the MergeMem as a whole.
3676 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
3677 //
3678 // (Here, the <N> notation gives the index of the relevant adr_type.)
3679 //
3680 // In one special case (and more cases in the future), alias categories overlap.
3681 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
3682 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
3683 // it is exactly equivalent to that state W:
3684 // MergeMem(<Bot>: W) <==> W
3685 //
3686 // Usually, the merge has more than one input. In that case, where inputs
3687 // overlap (i.e., one is Bot), the narrower alias type determines the memory
3688 // state for that type, and the wider alias type (Bot) fills in everywhere else:
3689 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
3690 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
3691 //
3692 // A merge can take a "wide" memory state as one of its narrow inputs.
3693 // This simply means that the merge observes out only the relevant parts of
3694 // the wide input. That is, wide memory states arriving at narrow merge inputs
3695 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
3696 //
3697 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
3698 // and that memory slices "leak through":
3699 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
3700 //
3701 // But, in such a cascade, repeated memory slices can "block the leak":
3702 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
3703 //
3704 // In the last example, Y is not part of the combined memory state of the
3705 // outermost MergeMem. The system must, of course, prevent unschedulable
3706 // memory states from arising, so you can be sure that the state Y is somehow
3707 // a precursor to state Y'.
3708 //
3709 //
3710 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
3711 // of each MergeMemNode array are exactly the numerical alias indexes, including
3712 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
3713 // Compile::alias_type (and kin) produce and manage these indexes.
3714 //
3715 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
3716 // (Note that this provides quick access to the top node inside MergeMem methods,
3717 // without the need to reach out via TLS to Compile::current.)
3718 //
3719 // As a consequence of what was just described, a MergeMem that represents a full
3720 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
3721 // containing all alias categories.
3722 //
3723 // MergeMem nodes never (?) have control inputs, so in(0) is NULL.
3724 //
3725 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
3726 // a memory state for the alias type <N>, or else the top node, meaning that
3727 // there is no particular input for that alias type. Note that the length of
3728 // a MergeMem is variable, and may be extended at any time to accommodate new
3729 // memory states at larger alias indexes. When merges grow, they are of course
3730 // filled with "top" in the unused in() positions.
3731 //
3732 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
3733 // (Top was chosen because it works smoothly with passes like GCM.)
3734 //
3735 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
3736 // the type of random VM bits like TLS references.) Since it is always the
3737 // first non-Bot memory slice, some low-level loops use it to initialize an
3738 // index variable: for (i = AliasIdxRaw; i < req(); i++).
3739 //
3740 //
3741 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
3742 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
3743 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
3744 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
3745 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
3746 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
3747 //
3748 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
3749 // really that different from the other memory inputs. An abbreviation called
3750 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
3751 //
3752 //
3753 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
3754 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
3755 // that "emerges though" the base memory will be marked as excluding the alias types
3756 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
3757 //
3758 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
3759 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
3760 //
3761 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
3762 // (It is currently unimplemented.) As you can see, the resulting merge is
3763 // actually a disjoint union of memory states, rather than an overlay.
3764 //
3766 //------------------------------MergeMemNode-----------------------------------
3767 Node* MergeMemNode::make_empty_memory() {
3768 Node* empty_memory = (Node*) Compile::current()->top();
3769 assert(empty_memory->is_top(), "correct sentinel identity");
3770 return empty_memory;
3771 }
3773 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
3774 init_class_id(Class_MergeMem);
3775 // all inputs are nullified in Node::Node(int)
3776 // set_input(0, NULL); // no control input
3778 // Initialize the edges uniformly to top, for starters.
3779 Node* empty_mem = make_empty_memory();
3780 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
3781 init_req(i,empty_mem);
3782 }
3783 assert(empty_memory() == empty_mem, "");
3785 if( new_base != NULL && new_base->is_MergeMem() ) {
3786 MergeMemNode* mdef = new_base->as_MergeMem();
3787 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
3788 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
3789 mms.set_memory(mms.memory2());
3790 }
3791 assert(base_memory() == mdef->base_memory(), "");
3792 } else {
3793 set_base_memory(new_base);
3794 }
3795 }
3797 // Make a new, untransformed MergeMem with the same base as 'mem'.
3798 // If mem is itself a MergeMem, populate the result with the same edges.
3799 MergeMemNode* MergeMemNode::make(Compile* C, Node* mem) {
3800 return new(C, 1+Compile::AliasIdxRaw) MergeMemNode(mem);
3801 }
3803 //------------------------------cmp--------------------------------------------
3804 uint MergeMemNode::hash() const { return NO_HASH; }
3805 uint MergeMemNode::cmp( const Node &n ) const {
3806 return (&n == this); // Always fail except on self
3807 }
3809 //------------------------------Identity---------------------------------------
3810 Node* MergeMemNode::Identity(PhaseTransform *phase) {
3811 // Identity if this merge point does not record any interesting memory
3812 // disambiguations.
3813 Node* base_mem = base_memory();
3814 Node* empty_mem = empty_memory();
3815 if (base_mem != empty_mem) { // Memory path is not dead?
3816 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3817 Node* mem = in(i);
3818 if (mem != empty_mem && mem != base_mem) {
3819 return this; // Many memory splits; no change
3820 }
3821 }
3822 }
3823 return base_mem; // No memory splits; ID on the one true input
3824 }
3826 //------------------------------Ideal------------------------------------------
3827 // This method is invoked recursively on chains of MergeMem nodes
3828 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3829 // Remove chain'd MergeMems
3830 //
3831 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
3832 // relative to the "in(Bot)". Since we are patching both at the same time,
3833 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
3834 // but rewrite each "in(i)" relative to the new "in(Bot)".
3835 Node *progress = NULL;
3838 Node* old_base = base_memory();
3839 Node* empty_mem = empty_memory();
3840 if (old_base == empty_mem)
3841 return NULL; // Dead memory path.
3843 MergeMemNode* old_mbase;
3844 if (old_base != NULL && old_base->is_MergeMem())
3845 old_mbase = old_base->as_MergeMem();
3846 else
3847 old_mbase = NULL;
3848 Node* new_base = old_base;
3850 // simplify stacked MergeMems in base memory
3851 if (old_mbase) new_base = old_mbase->base_memory();
3853 // the base memory might contribute new slices beyond my req()
3854 if (old_mbase) grow_to_match(old_mbase);
3856 // Look carefully at the base node if it is a phi.
3857 PhiNode* phi_base;
3858 if (new_base != NULL && new_base->is_Phi())
3859 phi_base = new_base->as_Phi();
3860 else
3861 phi_base = NULL;
3863 Node* phi_reg = NULL;
3864 uint phi_len = (uint)-1;
3865 if (phi_base != NULL && !phi_base->is_copy()) {
3866 // do not examine phi if degraded to a copy
3867 phi_reg = phi_base->region();
3868 phi_len = phi_base->req();
3869 // see if the phi is unfinished
3870 for (uint i = 1; i < phi_len; i++) {
3871 if (phi_base->in(i) == NULL) {
3872 // incomplete phi; do not look at it yet!
3873 phi_reg = NULL;
3874 phi_len = (uint)-1;
3875 break;
3876 }
3877 }
3878 }
3880 // Note: We do not call verify_sparse on entry, because inputs
3881 // can normalize to the base_memory via subsume_node or similar
3882 // mechanisms. This method repairs that damage.
3884 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
3886 // Look at each slice.
3887 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3888 Node* old_in = in(i);
3889 // calculate the old memory value
3890 Node* old_mem = old_in;
3891 if (old_mem == empty_mem) old_mem = old_base;
3892 assert(old_mem == memory_at(i), "");
3894 // maybe update (reslice) the old memory value
3896 // simplify stacked MergeMems
3897 Node* new_mem = old_mem;
3898 MergeMemNode* old_mmem;
3899 if (old_mem != NULL && old_mem->is_MergeMem())
3900 old_mmem = old_mem->as_MergeMem();
3901 else
3902 old_mmem = NULL;
3903 if (old_mmem == this) {
3904 // This can happen if loops break up and safepoints disappear.
3905 // A merge of BotPtr (default) with a RawPtr memory derived from a
3906 // safepoint can be rewritten to a merge of the same BotPtr with
3907 // the BotPtr phi coming into the loop. If that phi disappears
3908 // also, we can end up with a self-loop of the mergemem.
3909 // In general, if loops degenerate and memory effects disappear,
3910 // a mergemem can be left looking at itself. This simply means
3911 // that the mergemem's default should be used, since there is
3912 // no longer any apparent effect on this slice.
3913 // Note: If a memory slice is a MergeMem cycle, it is unreachable
3914 // from start. Update the input to TOP.
3915 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
3916 }
3917 else if (old_mmem != NULL) {
3918 new_mem = old_mmem->memory_at(i);
3919 }
3920 // else preceding memory was not a MergeMem
3922 // replace equivalent phis (unfortunately, they do not GVN together)
3923 if (new_mem != NULL && new_mem != new_base &&
3924 new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
3925 if (new_mem->is_Phi()) {
3926 PhiNode* phi_mem = new_mem->as_Phi();
3927 for (uint i = 1; i < phi_len; i++) {
3928 if (phi_base->in(i) != phi_mem->in(i)) {
3929 phi_mem = NULL;
3930 break;
3931 }
3932 }
3933 if (phi_mem != NULL) {
3934 // equivalent phi nodes; revert to the def
3935 new_mem = new_base;
3936 }
3937 }
3938 }
3940 // maybe store down a new value
3941 Node* new_in = new_mem;
3942 if (new_in == new_base) new_in = empty_mem;
3944 if (new_in != old_in) {
3945 // Warning: Do not combine this "if" with the previous "if"
3946 // A memory slice might have be be rewritten even if it is semantically
3947 // unchanged, if the base_memory value has changed.
3948 set_req(i, new_in);
3949 progress = this; // Report progress
3950 }
3951 }
3953 if (new_base != old_base) {
3954 set_req(Compile::AliasIdxBot, new_base);
3955 // Don't use set_base_memory(new_base), because we need to update du.
3956 assert(base_memory() == new_base, "");
3957 progress = this;
3958 }
3960 if( base_memory() == this ) {
3961 // a self cycle indicates this memory path is dead
3962 set_req(Compile::AliasIdxBot, empty_mem);
3963 }
3965 // Resolve external cycles by calling Ideal on a MergeMem base_memory
3966 // Recursion must occur after the self cycle check above
3967 if( base_memory()->is_MergeMem() ) {
3968 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
3969 Node *m = phase->transform(new_mbase); // Rollup any cycles
3970 if( m != NULL && (m->is_top() ||
3971 m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem) ) {
3972 // propagate rollup of dead cycle to self
3973 set_req(Compile::AliasIdxBot, empty_mem);
3974 }
3975 }
3977 if( base_memory() == empty_mem ) {
3978 progress = this;
3979 // Cut inputs during Parse phase only.
3980 // During Optimize phase a dead MergeMem node will be subsumed by Top.
3981 if( !can_reshape ) {
3982 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
3983 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
3984 }
3985 }
3986 }
3988 if( !progress && base_memory()->is_Phi() && can_reshape ) {
3989 // Check if PhiNode::Ideal's "Split phis through memory merges"
3990 // transform should be attempted. Look for this->phi->this cycle.
3991 uint merge_width = req();
3992 if (merge_width > Compile::AliasIdxRaw) {
3993 PhiNode* phi = base_memory()->as_Phi();
3994 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
3995 if (phi->in(i) == this) {
3996 phase->is_IterGVN()->_worklist.push(phi);
3997 break;
3998 }
3999 }
4000 }
4001 }
4003 assert(progress || verify_sparse(), "please, no dups of base");
4004 return progress;
4005 }
4007 //-------------------------set_base_memory-------------------------------------
4008 void MergeMemNode::set_base_memory(Node *new_base) {
4009 Node* empty_mem = empty_memory();
4010 set_req(Compile::AliasIdxBot, new_base);
4011 assert(memory_at(req()) == new_base, "must set default memory");
4012 // Clear out other occurrences of new_base:
4013 if (new_base != empty_mem) {
4014 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4015 if (in(i) == new_base) set_req(i, empty_mem);
4016 }
4017 }
4018 }
4020 //------------------------------out_RegMask------------------------------------
4021 const RegMask &MergeMemNode::out_RegMask() const {
4022 return RegMask::Empty;
4023 }
4025 //------------------------------dump_spec--------------------------------------
4026 #ifndef PRODUCT
4027 void MergeMemNode::dump_spec(outputStream *st) const {
4028 st->print(" {");
4029 Node* base_mem = base_memory();
4030 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
4031 Node* mem = memory_at(i);
4032 if (mem == base_mem) { st->print(" -"); continue; }
4033 st->print( " N%d:", mem->_idx );
4034 Compile::current()->get_adr_type(i)->dump_on(st);
4035 }
4036 st->print(" }");
4037 }
4038 #endif // !PRODUCT
4041 #ifdef ASSERT
4042 static bool might_be_same(Node* a, Node* b) {
4043 if (a == b) return true;
4044 if (!(a->is_Phi() || b->is_Phi())) return false;
4045 // phis shift around during optimization
4046 return true; // pretty stupid...
4047 }
4049 // verify a narrow slice (either incoming or outgoing)
4050 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
4051 if (!VerifyAliases) return; // don't bother to verify unless requested
4052 if (is_error_reported()) return; // muzzle asserts when debugging an error
4053 if (Node::in_dump()) return; // muzzle asserts when printing
4054 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
4055 assert(n != NULL, "");
4056 // Elide intervening MergeMem's
4057 while (n->is_MergeMem()) {
4058 n = n->as_MergeMem()->memory_at(alias_idx);
4059 }
4060 Compile* C = Compile::current();
4061 const TypePtr* n_adr_type = n->adr_type();
4062 if (n == m->empty_memory()) {
4063 // Implicit copy of base_memory()
4064 } else if (n_adr_type != TypePtr::BOTTOM) {
4065 assert(n_adr_type != NULL, "new memory must have a well-defined adr_type");
4066 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
4067 } else {
4068 // A few places like make_runtime_call "know" that VM calls are narrow,
4069 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
4070 bool expected_wide_mem = false;
4071 if (n == m->base_memory()) {
4072 expected_wide_mem = true;
4073 } else if (alias_idx == Compile::AliasIdxRaw ||
4074 n == m->memory_at(Compile::AliasIdxRaw)) {
4075 expected_wide_mem = true;
4076 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
4077 // memory can "leak through" calls on channels that
4078 // are write-once. Allow this also.
4079 expected_wide_mem = true;
4080 }
4081 assert(expected_wide_mem, "expected narrow slice replacement");
4082 }
4083 }
4084 #else // !ASSERT
4085 #define verify_memory_slice(m,i,n) (0) // PRODUCT version is no-op
4086 #endif
4089 //-----------------------------memory_at---------------------------------------
4090 Node* MergeMemNode::memory_at(uint alias_idx) const {
4091 assert(alias_idx >= Compile::AliasIdxRaw ||
4092 alias_idx == Compile::AliasIdxBot && Compile::current()->AliasLevel() == 0,
4093 "must avoid base_memory and AliasIdxTop");
4095 // Otherwise, it is a narrow slice.
4096 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
4097 Compile *C = Compile::current();
4098 if (is_empty_memory(n)) {
4099 // the array is sparse; empty slots are the "top" node
4100 n = base_memory();
4101 assert(Node::in_dump()
4102 || n == NULL || n->bottom_type() == Type::TOP
4103 || n->adr_type() == NULL // address is TOP
4104 || n->adr_type() == TypePtr::BOTTOM
4105 || n->adr_type() == TypeRawPtr::BOTTOM
4106 || Compile::current()->AliasLevel() == 0,
4107 "must be a wide memory");
4108 // AliasLevel == 0 if we are organizing the memory states manually.
4109 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
4110 } else {
4111 // make sure the stored slice is sane
4112 #ifdef ASSERT
4113 if (is_error_reported() || Node::in_dump()) {
4114 } else if (might_be_same(n, base_memory())) {
4115 // Give it a pass: It is a mostly harmless repetition of the base.
4116 // This can arise normally from node subsumption during optimization.
4117 } else {
4118 verify_memory_slice(this, alias_idx, n);
4119 }
4120 #endif
4121 }
4122 return n;
4123 }
4125 //---------------------------set_memory_at-------------------------------------
4126 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
4127 verify_memory_slice(this, alias_idx, n);
4128 Node* empty_mem = empty_memory();
4129 if (n == base_memory()) n = empty_mem; // collapse default
4130 uint need_req = alias_idx+1;
4131 if (req() < need_req) {
4132 if (n == empty_mem) return; // already the default, so do not grow me
4133 // grow the sparse array
4134 do {
4135 add_req(empty_mem);
4136 } while (req() < need_req);
4137 }
4138 set_req( alias_idx, n );
4139 }
4143 //--------------------------iteration_setup------------------------------------
4144 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
4145 if (other != NULL) {
4146 grow_to_match(other);
4147 // invariant: the finite support of mm2 is within mm->req()
4148 #ifdef ASSERT
4149 for (uint i = req(); i < other->req(); i++) {
4150 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
4151 }
4152 #endif
4153 }
4154 // Replace spurious copies of base_memory by top.
4155 Node* base_mem = base_memory();
4156 if (base_mem != NULL && !base_mem->is_top()) {
4157 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
4158 if (in(i) == base_mem)
4159 set_req(i, empty_memory());
4160 }
4161 }
4162 }
4164 //---------------------------grow_to_match-------------------------------------
4165 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
4166 Node* empty_mem = empty_memory();
4167 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
4168 // look for the finite support of the other memory
4169 for (uint i = other->req(); --i >= req(); ) {
4170 if (other->in(i) != empty_mem) {
4171 uint new_len = i+1;
4172 while (req() < new_len) add_req(empty_mem);
4173 break;
4174 }
4175 }
4176 }
4178 //---------------------------verify_sparse-------------------------------------
4179 #ifndef PRODUCT
4180 bool MergeMemNode::verify_sparse() const {
4181 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
4182 Node* base_mem = base_memory();
4183 // The following can happen in degenerate cases, since empty==top.
4184 if (is_empty_memory(base_mem)) return true;
4185 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
4186 assert(in(i) != NULL, "sane slice");
4187 if (in(i) == base_mem) return false; // should have been the sentinel value!
4188 }
4189 return true;
4190 }
4192 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
4193 Node* n;
4194 n = mm->in(idx);
4195 if (mem == n) return true; // might be empty_memory()
4196 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
4197 if (mem == n) return true;
4198 while (n->is_Phi() && (n = n->as_Phi()->is_copy()) != NULL) {
4199 if (mem == n) return true;
4200 if (n == NULL) break;
4201 }
4202 return false;
4203 }
4204 #endif // !PRODUCT