1 /*
2 * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/barrierSet.hpp"
27 #include "gc/shared/c2/barrierSetC2.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "opto/block.hpp"
31 #include "opto/callnode.hpp"
32 #include "opto/castnode.hpp"
33 #include "opto/cfgnode.hpp"
34 #include "opto/idealGraphPrinter.hpp"
35 #include "opto/loopnode.hpp"
36 #include "opto/machnode.hpp"
37 #include "opto/opcodes.hpp"
38 #include "opto/phaseX.hpp"
39 #include "opto/regalloc.hpp"
40 #include "opto/rootnode.hpp"
41 #include "utilities/macros.hpp"
42 #include "utilities/powerOfTwo.hpp"
43
44 //=============================================================================
45 #define NODE_HASH_MINIMUM_SIZE 255
46
47 //------------------------------NodeHash---------------------------------------
48 NodeHash::NodeHash(Arena *arena, uint est_max_size) :
49 _a(arena),
50 _max( round_up(est_max_size < NODE_HASH_MINIMUM_SIZE ? NODE_HASH_MINIMUM_SIZE : est_max_size) ),
51 _inserts(0), _insert_limit( insert_limit() ),
52 _table( NEW_ARENA_ARRAY( _a , Node* , _max ) )
53 #ifndef PRODUCT
54 , _grows(0),_look_probes(0), _lookup_hits(0), _lookup_misses(0),
55 _insert_probes(0), _delete_probes(0), _delete_hits(0), _delete_misses(0),
56 _total_inserts(0), _total_insert_probes(0)
57 #endif
58 {
59 // _sentinel must be in the current node space
60 _sentinel = new ProjNode(nullptr, TypeFunc::Control);
61 memset(_table,0,sizeof(Node*)*_max);
62 }
63
64 //------------------------------hash_find--------------------------------------
65 // Find in hash table
66 Node *NodeHash::hash_find( const Node *n ) {
67 // ((Node*)n)->set_hash( n->hash() );
68 uint hash = n->hash();
69 if (hash == Node::NO_HASH) {
70 NOT_PRODUCT( _lookup_misses++ );
71 return nullptr;
72 }
73 uint key = hash & (_max-1);
74 uint stride = key | 0x01;
75 NOT_PRODUCT( _look_probes++ );
76 Node *k = _table[key]; // Get hashed value
77 if( !k ) { // ?Miss?
78 NOT_PRODUCT( _lookup_misses++ );
79 return nullptr; // Miss!
80 }
81
82 int op = n->Opcode();
83 uint req = n->req();
84 while( 1 ) { // While probing hash table
85 if( k->req() == req && // Same count of inputs
86 k->Opcode() == op ) { // Same Opcode
87 for( uint i=0; i<req; i++ )
88 if( n->in(i)!=k->in(i)) // Different inputs?
89 goto collision; // "goto" is a speed hack...
90 if( n->cmp(*k) ) { // Check for any special bits
91 NOT_PRODUCT( _lookup_hits++ );
92 return k; // Hit!
93 }
94 }
95 collision:
96 NOT_PRODUCT( _look_probes++ );
97 key = (key + stride/*7*/) & (_max-1); // Stride through table with relative prime
98 k = _table[key]; // Get hashed value
99 if( !k ) { // ?Miss?
100 NOT_PRODUCT( _lookup_misses++ );
101 return nullptr; // Miss!
102 }
103 }
104 ShouldNotReachHere();
105 return nullptr;
106 }
107
108 //------------------------------hash_find_insert-------------------------------
109 // Find in hash table, insert if not already present
110 // Used to preserve unique entries in hash table
111 Node *NodeHash::hash_find_insert( Node *n ) {
112 // n->set_hash( );
113 uint hash = n->hash();
114 if (hash == Node::NO_HASH) {
115 NOT_PRODUCT( _lookup_misses++ );
116 return nullptr;
117 }
118 uint key = hash & (_max-1);
119 uint stride = key | 0x01; // stride must be relatively prime to table siz
120 uint first_sentinel = 0; // replace a sentinel if seen.
121 NOT_PRODUCT( _look_probes++ );
122 Node *k = _table[key]; // Get hashed value
123 if( !k ) { // ?Miss?
124 NOT_PRODUCT( _lookup_misses++ );
125 _table[key] = n; // Insert into table!
126 debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
127 check_grow(); // Grow table if insert hit limit
128 return nullptr; // Miss!
129 }
130 else if( k == _sentinel ) {
131 first_sentinel = key; // Can insert here
132 }
133
134 int op = n->Opcode();
135 uint req = n->req();
136 while( 1 ) { // While probing hash table
137 if( k->req() == req && // Same count of inputs
138 k->Opcode() == op ) { // Same Opcode
139 for( uint i=0; i<req; i++ )
140 if( n->in(i)!=k->in(i)) // Different inputs?
141 goto collision; // "goto" is a speed hack...
142 if( n->cmp(*k) ) { // Check for any special bits
143 NOT_PRODUCT( _lookup_hits++ );
144 return k; // Hit!
145 }
146 }
147 collision:
148 NOT_PRODUCT( _look_probes++ );
149 key = (key + stride) & (_max-1); // Stride through table w/ relative prime
150 k = _table[key]; // Get hashed value
151 if( !k ) { // ?Miss?
152 NOT_PRODUCT( _lookup_misses++ );
153 key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
154 _table[key] = n; // Insert into table!
155 debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
156 check_grow(); // Grow table if insert hit limit
157 return nullptr; // Miss!
158 }
159 else if( first_sentinel == 0 && k == _sentinel ) {
160 first_sentinel = key; // Can insert here
161 }
162
163 }
164 ShouldNotReachHere();
165 return nullptr;
166 }
167
168 //------------------------------hash_insert------------------------------------
169 // Insert into hash table
170 void NodeHash::hash_insert( Node *n ) {
171 // // "conflict" comments -- print nodes that conflict
172 // bool conflict = false;
173 // n->set_hash();
174 uint hash = n->hash();
175 if (hash == Node::NO_HASH) {
176 return;
177 }
178 check_grow();
179 uint key = hash & (_max-1);
180 uint stride = key | 0x01;
181
182 while( 1 ) { // While probing hash table
183 NOT_PRODUCT( _insert_probes++ );
184 Node *k = _table[key]; // Get hashed value
185 if( !k || (k == _sentinel) ) break; // Found a slot
186 assert( k != n, "already inserted" );
187 // if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print(" conflict: "); k->dump(); conflict = true; }
188 key = (key + stride) & (_max-1); // Stride through table w/ relative prime
189 }
190 _table[key] = n; // Insert into table!
191 debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
192 // if( conflict ) { n->dump(); }
193 }
194
195 //------------------------------hash_delete------------------------------------
196 // Replace in hash table with sentinel
197 bool NodeHash::hash_delete( const Node *n ) {
198 Node *k;
199 uint hash = n->hash();
200 if (hash == Node::NO_HASH) {
201 NOT_PRODUCT( _delete_misses++ );
202 return false;
203 }
204 uint key = hash & (_max-1);
205 uint stride = key | 0x01;
206 debug_only( uint counter = 0; );
207 for( ; /* (k != nullptr) && (k != _sentinel) */; ) {
208 debug_only( counter++ );
209 NOT_PRODUCT( _delete_probes++ );
210 k = _table[key]; // Get hashed value
211 if( !k ) { // Miss?
212 NOT_PRODUCT( _delete_misses++ );
213 return false; // Miss! Not in chain
214 }
215 else if( n == k ) {
216 NOT_PRODUCT( _delete_hits++ );
217 _table[key] = _sentinel; // Hit! Label as deleted entry
218 debug_only(((Node*)n)->exit_hash_lock()); // Unlock the node upon removal from table.
219 return true;
220 }
221 else {
222 // collision: move through table with prime offset
223 key = (key + stride/*7*/) & (_max-1);
224 assert( counter <= _insert_limit, "Cycle in hash-table");
225 }
226 }
227 ShouldNotReachHere();
228 return false;
229 }
230
231 //------------------------------round_up---------------------------------------
232 // Round up to nearest power of 2
233 uint NodeHash::round_up(uint x) {
234 x += (x >> 2); // Add 25% slop
235 return MAX2(16U, round_up_power_of_2(x));
236 }
237
238 //------------------------------grow-------------------------------------------
239 // Grow _table to next power of 2 and insert old entries
240 void NodeHash::grow() {
241 // Record old state
242 uint old_max = _max;
243 Node **old_table = _table;
244 // Construct new table with twice the space
245 #ifndef PRODUCT
246 _grows++;
247 _total_inserts += _inserts;
248 _total_insert_probes += _insert_probes;
249 _insert_probes = 0;
250 #endif
251 _inserts = 0;
252 _max = _max << 1;
253 _table = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
254 memset(_table,0,sizeof(Node*)*_max);
255 _insert_limit = insert_limit();
256 // Insert old entries into the new table
257 for( uint i = 0; i < old_max; i++ ) {
258 Node *m = *old_table++;
259 if( !m || m == _sentinel ) continue;
260 debug_only(m->exit_hash_lock()); // Unlock the node upon removal from old table.
261 hash_insert(m);
262 }
263 }
264
265 //------------------------------clear------------------------------------------
266 // Clear all entries in _table to null but keep storage
267 void NodeHash::clear() {
268 #ifdef ASSERT
269 // Unlock all nodes upon removal from table.
270 for (uint i = 0; i < _max; i++) {
271 Node* n = _table[i];
272 if (!n || n == _sentinel) continue;
273 n->exit_hash_lock();
274 }
275 #endif
276
277 memset( _table, 0, _max * sizeof(Node*) );
278 }
279
280 //-----------------------remove_useless_nodes----------------------------------
281 // Remove useless nodes from value table,
282 // implementation does not depend on hash function
283 void NodeHash::remove_useless_nodes(VectorSet &useful) {
284
285 // Dead nodes in the hash table inherited from GVN should not replace
286 // existing nodes, remove dead nodes.
287 uint max = size();
288 Node *sentinel_node = sentinel();
289 for( uint i = 0; i < max; ++i ) {
290 Node *n = at(i);
291 if(n != nullptr && n != sentinel_node && !useful.test(n->_idx)) {
292 debug_only(n->exit_hash_lock()); // Unlock the node when removed
293 _table[i] = sentinel_node; // Replace with placeholder
294 }
295 }
296 }
297
298
299 void NodeHash::check_no_speculative_types() {
300 #ifdef ASSERT
301 uint max = size();
302 Unique_Node_List live_nodes;
303 Compile::current()->identify_useful_nodes(live_nodes);
304 Node *sentinel_node = sentinel();
305 for (uint i = 0; i < max; ++i) {
306 Node *n = at(i);
307 if (n != nullptr &&
308 n != sentinel_node &&
309 n->is_Type() &&
310 live_nodes.member(n)) {
311 TypeNode* tn = n->as_Type();
312 const Type* t = tn->type();
313 const Type* t_no_spec = t->remove_speculative();
314 assert(t == t_no_spec, "dead node in hash table or missed node during speculative cleanup");
315 }
316 }
317 #endif
318 }
319
320 #ifndef PRODUCT
321 //------------------------------dump-------------------------------------------
322 // Dump statistics for the hash table
323 void NodeHash::dump() {
324 _total_inserts += _inserts;
325 _total_insert_probes += _insert_probes;
326 if (PrintCompilation && PrintOptoStatistics && Verbose && (_inserts > 0)) {
327 if (WizardMode) {
328 for (uint i=0; i<_max; i++) {
329 if (_table[i])
330 tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
331 }
332 }
333 tty->print("\nGVN Hash stats: %d grows to %d max_size\n", _grows, _max);
334 tty->print(" %d/%d (%8.1f%% full)\n", _inserts, _max, (double)_inserts/_max*100.0);
335 tty->print(" %dp/(%dh+%dm) (%8.2f probes/lookup)\n", _look_probes, _lookup_hits, _lookup_misses, (double)_look_probes/(_lookup_hits+_lookup_misses));
336 tty->print(" %dp/%di (%8.2f probes/insert)\n", _total_insert_probes, _total_inserts, (double)_total_insert_probes/_total_inserts);
337 // sentinels increase lookup cost, but not insert cost
338 assert((_lookup_misses+_lookup_hits)*4+100 >= _look_probes, "bad hash function");
339 assert( _inserts+(_inserts>>3) < _max, "table too full" );
340 assert( _inserts*3+100 >= _insert_probes, "bad hash function" );
341 }
342 }
343
344 Node *NodeHash::find_index(uint idx) { // For debugging
345 // Find an entry by its index value
346 for( uint i = 0; i < _max; i++ ) {
347 Node *m = _table[i];
348 if( !m || m == _sentinel ) continue;
349 if( m->_idx == (uint)idx ) return m;
350 }
351 return nullptr;
352 }
353 #endif
354
355 #ifdef ASSERT
356 NodeHash::~NodeHash() {
357 // Unlock all nodes upon destruction of table.
358 if (_table != (Node**)badAddress) clear();
359 }
360 #endif
361
362
363 //=============================================================================
364 //------------------------------PhaseRemoveUseless-----------------------------
365 // 1) Use a breadthfirst walk to collect useful nodes reachable from root.
366 PhaseRemoveUseless::PhaseRemoveUseless(PhaseGVN* gvn, Unique_Node_List& worklist, PhaseNumber phase_num) : Phase(phase_num) {
367 C->print_method(PHASE_BEFORE_REMOVEUSELESS, 3);
368 // Implementation requires an edge from root to each SafePointNode
369 // at a backward branch. Inserted in add_safepoint().
370
371 // Identify nodes that are reachable from below, useful.
372 C->identify_useful_nodes(_useful);
373 // Update dead node list
374 C->update_dead_node_list(_useful);
375
376 // Remove all useless nodes from PhaseValues' recorded types
377 // Must be done before disconnecting nodes to preserve hash-table-invariant
378 gvn->remove_useless_nodes(_useful.member_set());
379
380 // Remove all useless nodes from future worklist
381 worklist.remove_useless_nodes(_useful.member_set());
382
383 // Disconnect 'useless' nodes that are adjacent to useful nodes
384 C->disconnect_useless_nodes(_useful, worklist);
385 }
386
387 //=============================================================================
388 //------------------------------PhaseRenumberLive------------------------------
389 // First, remove useless nodes (equivalent to identifying live nodes).
390 // Then, renumber live nodes.
391 //
392 // The set of live nodes is returned by PhaseRemoveUseless in the _useful structure.
393 // If the number of live nodes is 'x' (where 'x' == _useful.size()), then the
394 // PhaseRenumberLive updates the node ID of each node (the _idx field) with a unique
395 // value in the range [0, x).
396 //
397 // At the end of the PhaseRenumberLive phase, the compiler's count of unique nodes is
398 // updated to 'x' and the list of dead nodes is reset (as there are no dead nodes).
399 //
400 // The PhaseRenumberLive phase updates two data structures with the new node IDs.
401 // (1) The "worklist" is "C->igvn_worklist()", which is to collect which nodes need to
402 // be processed by IGVN after removal of the useless nodes.
403 // (2) Type information "gvn->types()" (same as "C->types()") maps every node ID to
404 // the node's type. The mapping is updated to use the new node IDs as well. We
405 // create a new map, and swap it with the old one.
406 //
407 // Other data structures used by the compiler are not updated. The hash table for value
408 // numbering ("C->node_hash()", referenced by PhaseValue::_table) is not updated because
409 // computing the hash values is not based on node IDs.
410 PhaseRenumberLive::PhaseRenumberLive(PhaseGVN* gvn,
411 Unique_Node_List& worklist,
412 PhaseNumber phase_num) :
413 PhaseRemoveUseless(gvn, worklist, Remove_Useless_And_Renumber_Live),
414 _new_type_array(C->comp_arena()),
415 _old2new_map(C->unique(), C->unique(), -1),
416 _is_pass_finished(false),
417 _live_node_count(C->live_nodes())
418 {
419 assert(RenumberLiveNodes, "RenumberLiveNodes must be set to true for node renumbering to take place");
420 assert(C->live_nodes() == _useful.size(), "the number of live nodes must match the number of useful nodes");
421 assert(_delayed.size() == 0, "should be empty");
422 assert(&worklist == C->igvn_worklist(), "reference still same as the one from Compile");
423 assert(&gvn->types() == C->types(), "reference still same as that from Compile");
424
425 GrowableArray<Node_Notes*>* old_node_note_array = C->node_note_array();
426 if (old_node_note_array != nullptr) {
427 int new_size = (_useful.size() >> 8) + 1; // The node note array uses blocks, see C->_log2_node_notes_block_size
428 new_size = MAX2(8, new_size);
429 C->set_node_note_array(new (C->comp_arena()) GrowableArray<Node_Notes*> (C->comp_arena(), new_size, 0, nullptr));
430 C->grow_node_notes(C->node_note_array(), new_size);
431 }
432
433 assert(worklist.is_subset_of(_useful), "only useful nodes should still be in the worklist");
434
435 // Iterate over the set of live nodes.
436 for (uint current_idx = 0; current_idx < _useful.size(); current_idx++) {
437 Node* n = _useful.at(current_idx);
438
439 const Type* type = gvn->type_or_null(n);
440 _new_type_array.map(current_idx, type);
441
442 assert(_old2new_map.at(n->_idx) == -1, "already seen");
443 _old2new_map.at_put(n->_idx, current_idx);
444
445 if (old_node_note_array != nullptr) {
446 Node_Notes* nn = C->locate_node_notes(old_node_note_array, n->_idx);
447 C->set_node_notes_at(current_idx, nn);
448 }
449
450 n->set_idx(current_idx); // Update node ID.
451
452 if (update_embedded_ids(n) < 0) {
453 _delayed.push(n); // has embedded IDs; handle later
454 }
455 }
456
457 // VectorSet in Unique_Node_Set must be recomputed, since IDs have changed.
458 worklist.recompute_idx_set();
459
460 assert(_live_node_count == _useful.size(), "all live nodes must be processed");
461
462 _is_pass_finished = true; // pass finished; safe to process delayed updates
463
464 while (_delayed.size() > 0) {
465 Node* n = _delayed.pop();
466 int no_of_updates = update_embedded_ids(n);
467 assert(no_of_updates > 0, "should be updated");
468 }
469
470 // Replace the compiler's type information with the updated type information.
471 gvn->types().swap(_new_type_array);
472
473 // Update the unique node count of the compilation to the number of currently live nodes.
474 C->set_unique(_live_node_count);
475
476 // Set the dead node count to 0 and reset dead node list.
477 C->reset_dead_node_list();
478 }
479
480 int PhaseRenumberLive::new_index(int old_idx) {
481 assert(_is_pass_finished, "not finished");
482 if (_old2new_map.at(old_idx) == -1) { // absent
483 // Allocate a placeholder to preserve uniqueness
484 _old2new_map.at_put(old_idx, _live_node_count);
485 _live_node_count++;
486 }
487 return _old2new_map.at(old_idx);
488 }
489
490 int PhaseRenumberLive::update_embedded_ids(Node* n) {
491 int no_of_updates = 0;
492 if (n->is_Phi()) {
493 PhiNode* phi = n->as_Phi();
494 if (phi->_inst_id != -1) {
495 if (!_is_pass_finished) {
496 return -1; // delay
497 }
498 int new_idx = new_index(phi->_inst_id);
499 assert(new_idx != -1, "");
500 phi->_inst_id = new_idx;
501 no_of_updates++;
502 }
503 if (phi->_inst_mem_id != -1) {
504 if (!_is_pass_finished) {
505 return -1; // delay
506 }
507 int new_idx = new_index(phi->_inst_mem_id);
508 assert(new_idx != -1, "");
509 phi->_inst_mem_id = new_idx;
510 no_of_updates++;
511 }
512 }
513
514 const Type* type = _new_type_array.fast_lookup(n->_idx);
515 if (type != nullptr && type->isa_oopptr() && type->is_oopptr()->is_known_instance()) {
516 if (!_is_pass_finished) {
517 return -1; // delay
518 }
519 int old_idx = type->is_oopptr()->instance_id();
520 int new_idx = new_index(old_idx);
521 const Type* new_type = type->is_oopptr()->with_instance_id(new_idx);
522 _new_type_array.map(n->_idx, new_type);
523 no_of_updates++;
524 }
525
526 return no_of_updates;
527 }
528
529 void PhaseValues::init_con_caches() {
530 memset(_icons,0,sizeof(_icons));
531 memset(_lcons,0,sizeof(_lcons));
532 memset(_zcons,0,sizeof(_zcons));
533 }
534
535 //--------------------------------find_int_type--------------------------------
536 const TypeInt* PhaseValues::find_int_type(Node* n) {
537 if (n == nullptr) return nullptr;
538 // Call type_or_null(n) to determine node's type since we might be in
539 // parse phase and call n->Value() may return wrong type.
540 // (For example, a phi node at the beginning of loop parsing is not ready.)
541 const Type* t = type_or_null(n);
542 if (t == nullptr) return nullptr;
543 return t->isa_int();
544 }
545
546
547 //-------------------------------find_long_type--------------------------------
548 const TypeLong* PhaseValues::find_long_type(Node* n) {
549 if (n == nullptr) return nullptr;
550 // (See comment above on type_or_null.)
551 const Type* t = type_or_null(n);
552 if (t == nullptr) return nullptr;
553 return t->isa_long();
554 }
555
556 //------------------------------~PhaseValues-----------------------------------
557 #ifndef PRODUCT
558 PhaseValues::~PhaseValues() {
559 // Statistics for NodeHash
560 _table.dump();
561 // Statistics for value progress and efficiency
562 if( PrintCompilation && Verbose && WizardMode ) {
563 tty->print("\n%sValues: %d nodes ---> %d/%d (%d)",
564 is_IterGVN() ? "Iter" : " ", C->unique(), made_progress(), made_transforms(), made_new_values());
565 if( made_transforms() != 0 ) {
566 tty->print_cr(" ratio %f", made_progress()/(float)made_transforms() );
567 } else {
568 tty->cr();
569 }
570 }
571 }
572 #endif
573
574 //------------------------------makecon----------------------------------------
575 ConNode* PhaseValues::makecon(const Type* t) {
576 assert(t->singleton(), "must be a constant");
577 assert(!t->empty() || t == Type::TOP, "must not be vacuous range");
578 switch (t->base()) { // fast paths
579 case Type::Half:
580 case Type::Top: return (ConNode*) C->top();
581 case Type::Int: return intcon( t->is_int()->get_con() );
582 case Type::Long: return longcon( t->is_long()->get_con() );
583 default: break;
584 }
585 if (t->is_zero_type())
586 return zerocon(t->basic_type());
587 return uncached_makecon(t);
588 }
589
590 //--------------------------uncached_makecon-----------------------------------
591 // Make an idealized constant - one of ConINode, ConPNode, etc.
592 ConNode* PhaseValues::uncached_makecon(const Type *t) {
593 assert(t->singleton(), "must be a constant");
594 ConNode* x = ConNode::make(t);
595 ConNode* k = (ConNode*)hash_find_insert(x); // Value numbering
596 if (k == nullptr) {
597 set_type(x, t); // Missed, provide type mapping
598 GrowableArray<Node_Notes*>* nna = C->node_note_array();
599 if (nna != nullptr) {
600 Node_Notes* loc = C->locate_node_notes(nna, x->_idx, true);
601 loc->clear(); // do not put debug info on constants
602 }
603 } else {
604 x->destruct(this); // Hit, destroy duplicate constant
605 x = k; // use existing constant
606 }
607 return x;
608 }
609
610 //------------------------------intcon-----------------------------------------
611 // Fast integer constant. Same as "transform(new ConINode(TypeInt::make(i)))"
612 ConINode* PhaseValues::intcon(jint i) {
613 // Small integer? Check cache! Check that cached node is not dead
614 if (i >= _icon_min && i <= _icon_max) {
615 ConINode* icon = _icons[i-_icon_min];
616 if (icon != nullptr && icon->in(TypeFunc::Control) != nullptr)
617 return icon;
618 }
619 ConINode* icon = (ConINode*) uncached_makecon(TypeInt::make(i));
620 assert(icon->is_Con(), "");
621 if (i >= _icon_min && i <= _icon_max)
622 _icons[i-_icon_min] = icon; // Cache small integers
623 return icon;
624 }
625
626 //------------------------------longcon----------------------------------------
627 // Fast long constant.
628 ConLNode* PhaseValues::longcon(jlong l) {
629 // Small integer? Check cache! Check that cached node is not dead
630 if (l >= _lcon_min && l <= _lcon_max) {
631 ConLNode* lcon = _lcons[l-_lcon_min];
632 if (lcon != nullptr && lcon->in(TypeFunc::Control) != nullptr)
633 return lcon;
634 }
635 ConLNode* lcon = (ConLNode*) uncached_makecon(TypeLong::make(l));
636 assert(lcon->is_Con(), "");
637 if (l >= _lcon_min && l <= _lcon_max)
638 _lcons[l-_lcon_min] = lcon; // Cache small integers
639 return lcon;
640 }
641 ConNode* PhaseValues::integercon(jlong l, BasicType bt) {
642 if (bt == T_INT) {
643 return intcon(checked_cast<jint>(l));
644 }
645 assert(bt == T_LONG, "not an integer");
646 return longcon(l);
647 }
648
649
650 //------------------------------zerocon-----------------------------------------
651 // Fast zero or null constant. Same as "transform(ConNode::make(Type::get_zero_type(bt)))"
652 ConNode* PhaseValues::zerocon(BasicType bt) {
653 assert((uint)bt <= _zcon_max, "domain check");
654 ConNode* zcon = _zcons[bt];
655 if (zcon != nullptr && zcon->in(TypeFunc::Control) != nullptr)
656 return zcon;
657 zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
658 _zcons[bt] = zcon;
659 return zcon;
660 }
661
662
663
664 //=============================================================================
665 Node* PhaseGVN::apply_ideal(Node* k, bool can_reshape) {
666 Node* i = BarrierSet::barrier_set()->barrier_set_c2()->ideal_node(this, k, can_reshape);
667 if (i == nullptr) {
668 i = k->Ideal(this, can_reshape);
669 }
670 return i;
671 }
672
673 //------------------------------transform--------------------------------------
674 // Return a node which computes the same function as this node, but
675 // in a faster or cheaper fashion.
676 Node* PhaseGVN::transform(Node* n) {
677 NOT_PRODUCT( set_transforms(); )
678
679 // Apply the Ideal call in a loop until it no longer applies
680 Node* k = n;
681 Node* i = apply_ideal(k, /*can_reshape=*/false);
682 NOT_PRODUCT(uint loop_count = 1;)
683 while (i != nullptr) {
684 assert(i->_idx >= k->_idx, "Idealize should return new nodes, use Identity to return old nodes" );
685 k = i;
686 #ifdef ASSERT
687 if (loop_count >= K + C->live_nodes()) {
688 dump_infinite_loop_info(i, "PhaseGVN::transform");
689 }
690 #endif
691 i = apply_ideal(k, /*can_reshape=*/false);
692 NOT_PRODUCT(loop_count++;)
693 }
694 NOT_PRODUCT(if (loop_count != 0) { set_progress(); })
695
696 // If brand new node, make space in type array.
697 ensure_type_or_null(k);
698
699 // Since I just called 'Value' to compute the set of run-time values
700 // for this Node, and 'Value' is non-local (and therefore expensive) I'll
701 // cache Value. Later requests for the local phase->type of this Node can
702 // use the cached Value instead of suffering with 'bottom_type'.
703 const Type* t = k->Value(this); // Get runtime Value set
704 assert(t != nullptr, "value sanity");
705 if (type_or_null(k) != t) {
706 #ifndef PRODUCT
707 // Do not count initial visit to node as a transformation
708 if (type_or_null(k) == nullptr) {
709 inc_new_values();
710 set_progress();
711 }
712 #endif
713 set_type(k, t);
714 // If k is a TypeNode, capture any more-precise type permanently into Node
715 k->raise_bottom_type(t);
716 }
717
718 if (t->singleton() && !k->is_Con()) {
719 NOT_PRODUCT(set_progress();)
720 return makecon(t); // Turn into a constant
721 }
722
723 // Now check for Identities
724 i = k->Identity(this); // Look for a nearby replacement
725 if (i != k) { // Found? Return replacement!
726 NOT_PRODUCT(set_progress();)
727 return i;
728 }
729
730 // Global Value Numbering
731 i = hash_find_insert(k); // Insert if new
732 if (i && (i != k)) {
733 // Return the pre-existing node
734 NOT_PRODUCT(set_progress();)
735 return i;
736 }
737
738 // Return Idealized original
739 return k;
740 }
741
742 bool PhaseGVN::is_dominator_helper(Node *d, Node *n, bool linear_only) {
743 if (d->is_top() || (d->is_Proj() && d->in(0)->is_top())) {
744 return false;
745 }
746 if (n->is_top() || (n->is_Proj() && n->in(0)->is_top())) {
747 return false;
748 }
749 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
750 int i = 0;
751 while (d != n) {
752 n = IfNode::up_one_dom(n, linear_only);
753 i++;
754 if (n == nullptr || i >= 100) {
755 return false;
756 }
757 }
758 return true;
759 }
760
761 #ifdef ASSERT
762 //------------------------------dead_loop_check--------------------------------
763 // Check for a simple dead loop when a data node references itself directly
764 // or through an other data node excluding cons and phis.
765 void PhaseGVN::dead_loop_check( Node *n ) {
766 // Phi may reference itself in a loop
767 if (n != nullptr && !n->is_dead_loop_safe() && !n->is_CFG()) {
768 // Do 2 levels check and only data inputs.
769 bool no_dead_loop = true;
770 uint cnt = n->req();
771 for (uint i = 1; i < cnt && no_dead_loop; i++) {
772 Node *in = n->in(i);
773 if (in == n) {
774 no_dead_loop = false;
775 } else if (in != nullptr && !in->is_dead_loop_safe()) {
776 uint icnt = in->req();
777 for (uint j = 1; j < icnt && no_dead_loop; j++) {
778 if (in->in(j) == n || in->in(j) == in)
779 no_dead_loop = false;
780 }
781 }
782 }
783 if (!no_dead_loop) n->dump_bfs(100,nullptr,"#");
784 assert(no_dead_loop, "dead loop detected");
785 }
786 }
787
788
789 /**
790 * Dumps information that can help to debug the problem. A debug
791 * build fails with an assert.
792 */
793 void PhaseGVN::dump_infinite_loop_info(Node* n, const char* where) {
794 n->dump(4);
795 assert(false, "infinite loop in %s", where);
796 }
797 #endif
798
799 //=============================================================================
800 //------------------------------PhaseIterGVN-----------------------------------
801 // Initialize with previous PhaseIterGVN info; used by PhaseCCP
802 PhaseIterGVN::PhaseIterGVN(PhaseIterGVN* igvn) : _delay_transform(igvn->_delay_transform),
803 _worklist(*C->igvn_worklist())
804 {
805 _iterGVN = true;
806 assert(&_worklist == &igvn->_worklist, "sanity");
807 }
808
809 //------------------------------PhaseIterGVN-----------------------------------
810 // Initialize with previous PhaseGVN info from Parser
811 PhaseIterGVN::PhaseIterGVN(PhaseGVN* gvn) : _delay_transform(false),
812 _worklist(*C->igvn_worklist())
813 {
814 _iterGVN = true;
815 uint max;
816
817 // Dead nodes in the hash table inherited from GVN were not treated as
818 // roots during def-use info creation; hence they represent an invisible
819 // use. Clear them out.
820 max = _table.size();
821 for( uint i = 0; i < max; ++i ) {
822 Node *n = _table.at(i);
823 if(n != nullptr && n != _table.sentinel() && n->outcnt() == 0) {
824 if( n->is_top() ) continue;
825 // If remove_useless_nodes() has run, we expect no such nodes left.
826 assert(false, "remove_useless_nodes missed this node");
827 hash_delete(n);
828 }
829 }
830
831 // Any Phis or Regions on the worklist probably had uses that could not
832 // make more progress because the uses were made while the Phis and Regions
833 // were in half-built states. Put all uses of Phis and Regions on worklist.
834 max = _worklist.size();
835 for( uint j = 0; j < max; j++ ) {
836 Node *n = _worklist.at(j);
837 uint uop = n->Opcode();
838 if( uop == Op_Phi || uop == Op_Region ||
839 n->is_Type() ||
840 n->is_Mem() )
841 add_users_to_worklist(n);
842 }
843 }
844
845 void PhaseIterGVN::shuffle_worklist() {
846 if (_worklist.size() < 2) return;
847 for (uint i = _worklist.size() - 1; i >= 1; i--) {
848 uint j = C->random() % (i + 1);
849 swap(_worklist.adr()[i], _worklist.adr()[j]);
850 }
851 }
852
853 #ifndef PRODUCT
854 void PhaseIterGVN::verify_step(Node* n) {
855 if (is_verify_def_use()) {
856 ResourceMark rm;
857 VectorSet visited;
858 Node_List worklist;
859
860 _verify_window[_verify_counter % _verify_window_size] = n;
861 ++_verify_counter;
862 if (C->unique() < 1000 || 0 == _verify_counter % (C->unique() < 10000 ? 10 : 100)) {
863 ++_verify_full_passes;
864 worklist.push(C->root());
865 Node::verify(-1, visited, worklist);
866 return;
867 }
868 for (int i = 0; i < _verify_window_size; i++) {
869 Node* n = _verify_window[i];
870 if (n == nullptr) {
871 continue;
872 }
873 if (n->in(0) == NodeSentinel) { // xform_idom
874 _verify_window[i] = n->in(1);
875 --i;
876 continue;
877 }
878 // Typical fanout is 1-2, so this call visits about 6 nodes.
879 if (!visited.test_set(n->_idx)) {
880 worklist.push(n);
881 }
882 }
883 Node::verify(4, visited, worklist);
884 }
885 }
886
887 void PhaseIterGVN::trace_PhaseIterGVN(Node* n, Node* nn, const Type* oldtype) {
888 const Type* newtype = type_or_null(n);
889 if (nn != n || oldtype != newtype) {
890 C->print_method(PHASE_AFTER_ITER_GVN_STEP, 5, n);
891 }
892 if (TraceIterativeGVN) {
893 uint wlsize = _worklist.size();
894 if (nn != n) {
895 // print old node
896 tty->print("< ");
897 if (oldtype != newtype && oldtype != nullptr) {
898 oldtype->dump();
899 }
900 do { tty->print("\t"); } while (tty->position() < 16);
901 tty->print("<");
902 n->dump();
903 }
904 if (oldtype != newtype || nn != n) {
905 // print new node and/or new type
906 if (oldtype == nullptr) {
907 tty->print("* ");
908 } else if (nn != n) {
909 tty->print("> ");
910 } else {
911 tty->print("= ");
912 }
913 if (newtype == nullptr) {
914 tty->print("null");
915 } else {
916 newtype->dump();
917 }
918 do { tty->print("\t"); } while (tty->position() < 16);
919 nn->dump();
920 }
921 if (Verbose && wlsize < _worklist.size()) {
922 tty->print(" Push {");
923 while (wlsize != _worklist.size()) {
924 Node* pushed = _worklist.at(wlsize++);
925 tty->print(" %d", pushed->_idx);
926 }
927 tty->print_cr(" }");
928 }
929 if (nn != n) {
930 // ignore n, it might be subsumed
931 verify_step((Node*) nullptr);
932 }
933 }
934 }
935
936 void PhaseIterGVN::init_verifyPhaseIterGVN() {
937 _verify_counter = 0;
938 _verify_full_passes = 0;
939 for (int i = 0; i < _verify_window_size; i++) {
940 _verify_window[i] = nullptr;
941 }
942 #ifdef ASSERT
943 // Verify that all modified nodes are on _worklist
944 Unique_Node_List* modified_list = C->modified_nodes();
945 while (modified_list != nullptr && modified_list->size()) {
946 Node* n = modified_list->pop();
947 if (!n->is_Con() && !_worklist.member(n)) {
948 n->dump();
949 fatal("modified node is not on IGVN._worklist");
950 }
951 }
952 #endif
953 }
954
955 void PhaseIterGVN::verify_PhaseIterGVN() {
956 #ifdef ASSERT
957 // Verify nodes with changed inputs.
958 Unique_Node_List* modified_list = C->modified_nodes();
959 while (modified_list != nullptr && modified_list->size()) {
960 Node* n = modified_list->pop();
961 if (!n->is_Con()) { // skip Con nodes
962 n->dump();
963 fatal("modified node was not processed by IGVN.transform_old()");
964 }
965 }
966 #endif
967
968 C->verify_graph_edges();
969 if (is_verify_def_use() && PrintOpto) {
970 if (_verify_counter == _verify_full_passes) {
971 tty->print_cr("VerifyIterativeGVN: %d transforms and verify passes",
972 (int) _verify_full_passes);
973 } else {
974 tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
975 (int) _verify_counter, (int) _verify_full_passes);
976 }
977 }
978
979 #ifdef ASSERT
980 if (modified_list != nullptr) {
981 while (modified_list->size() > 0) {
982 Node* n = modified_list->pop();
983 n->dump();
984 assert(false, "VerifyIterativeGVN: new modified node was added");
985 }
986 }
987
988 verify_optimize();
989 #endif
990 }
991 #endif /* PRODUCT */
992
993 #ifdef ASSERT
994 /**
995 * Dumps information that can help to debug the problem. A debug
996 * build fails with an assert.
997 */
998 void PhaseIterGVN::dump_infinite_loop_info(Node* n, const char* where) {
999 n->dump(4);
1000 _worklist.dump();
1001 assert(false, "infinite loop in %s", where);
1002 }
1003
1004 /**
1005 * Prints out information about IGVN if the 'verbose' option is used.
1006 */
1007 void PhaseIterGVN::trace_PhaseIterGVN_verbose(Node* n, int num_processed) {
1008 if (TraceIterativeGVN && Verbose) {
1009 tty->print(" Pop ");
1010 n->dump();
1011 if ((num_processed % 100) == 0) {
1012 _worklist.print_set();
1013 }
1014 }
1015 }
1016 #endif /* ASSERT */
1017
1018 void PhaseIterGVN::optimize() {
1019 DEBUG_ONLY(uint num_processed = 0;)
1020 NOT_PRODUCT(init_verifyPhaseIterGVN();)
1021 NOT_PRODUCT(C->reset_igv_phase_iter(PHASE_AFTER_ITER_GVN_STEP);)
1022 C->print_method(PHASE_BEFORE_ITER_GVN, 3);
1023 if (StressIGVN) {
1024 shuffle_worklist();
1025 }
1026
1027 uint loop_count = 0;
1028 // Pull from worklist and transform the node. If the node has changed,
1029 // update edge info and put uses on worklist.
1030 while(_worklist.size()) {
1031 if (C->check_node_count(NodeLimitFudgeFactor * 2, "Out of nodes")) {
1032 C->print_method(PHASE_AFTER_ITER_GVN, 3);
1033 return;
1034 }
1035 Node* n = _worklist.pop();
1036 if (loop_count >= K * C->live_nodes()) {
1037 DEBUG_ONLY(dump_infinite_loop_info(n, "PhaseIterGVN::optimize");)
1038 C->record_method_not_compilable("infinite loop in PhaseIterGVN::optimize");
1039 C->print_method(PHASE_AFTER_ITER_GVN, 3);
1040 return;
1041 }
1042 DEBUG_ONLY(trace_PhaseIterGVN_verbose(n, num_processed++);)
1043 if (n->outcnt() != 0) {
1044 NOT_PRODUCT(const Type* oldtype = type_or_null(n));
1045 // Do the transformation
1046 Node* nn = transform_old(n);
1047 NOT_PRODUCT(trace_PhaseIterGVN(n, nn, oldtype);)
1048 } else if (!n->is_top()) {
1049 remove_dead_node(n);
1050 }
1051 loop_count++;
1052 }
1053 NOT_PRODUCT(verify_PhaseIterGVN();)
1054 C->print_method(PHASE_AFTER_ITER_GVN, 3);
1055 }
1056
1057 #ifdef ASSERT
1058 void PhaseIterGVN::verify_optimize() {
1059 if (is_verify_Value()) {
1060 ResourceMark rm;
1061 Unique_Node_List worklist;
1062 bool failure = false;
1063 // BFS all nodes, starting at root
1064 worklist.push(C->root());
1065 for (uint j = 0; j < worklist.size(); ++j) {
1066 Node* n = worklist.at(j);
1067 failure |= verify_node_value(n);
1068 // traverse all inputs and outputs
1069 for (uint i = 0; i < n->req(); i++) {
1070 if (n->in(i) != nullptr) {
1071 worklist.push(n->in(i));
1072 }
1073 }
1074 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1075 worklist.push(n->fast_out(i));
1076 }
1077 }
1078 // If we get this assert, check why the reported nodes were not processed again in IGVN.
1079 // We should either make sure that these nodes are properly added back to the IGVN worklist
1080 // in PhaseIterGVN::add_users_to_worklist to update them again or add an exception
1081 // in the verification code above if that is not possible for some reason (like Load nodes).
1082 assert(!failure, "Missed optimization opportunity in PhaseIterGVN");
1083 }
1084 }
1085
1086 // Check that type(n) == n->Value(), return true if we have a failure.
1087 // We have a list of exceptions, see detailed comments in code.
1088 // (1) Integer "widen" changes, but the range is the same.
1089 // (2) LoadNode performs deep traversals. Load is not notified for changes far away.
1090 // (3) CmpPNode performs deep traversals if it compares oopptr. CmpP is not notified for changes far away.
1091 bool PhaseIterGVN::verify_node_value(Node* n) {
1092 // If we assert inside type(n), because the type is still a null, then maybe
1093 // the node never went through gvn.transform, which would be a bug.
1094 const Type* told = type(n);
1095 const Type* tnew = n->Value(this);
1096 if (told == tnew) {
1097 return false;
1098 }
1099 // Exception (1)
1100 // Integer "widen" changes, but range is the same.
1101 if (told->isa_integer(tnew->basic_type()) != nullptr) { // both either int or long
1102 const TypeInteger* t0 = told->is_integer(tnew->basic_type());
1103 const TypeInteger* t1 = tnew->is_integer(tnew->basic_type());
1104 if (t0->lo_as_long() == t1->lo_as_long() &&
1105 t0->hi_as_long() == t1->hi_as_long()) {
1106 return false; // ignore integer widen
1107 }
1108 }
1109 // Exception (2)
1110 // LoadNode performs deep traversals. Load is not notified for changes far away.
1111 if (n->is_Load() && !told->singleton()) {
1112 // MemNode::can_see_stored_value looks up through many memory nodes,
1113 // which means we would need to notify modifications from far up in
1114 // the inputs all the way down to the LoadNode. We don't do that.
1115 return false;
1116 }
1117 // Exception (3)
1118 // CmpPNode performs deep traversals if it compares oopptr. CmpP is not notified for changes far away.
1119 if (n->Opcode() == Op_CmpP && type(n->in(1))->isa_oopptr() && type(n->in(2))->isa_oopptr()) {
1120 // SubNode::Value
1121 // CmpPNode::sub
1122 // MemNode::detect_ptr_independence
1123 // MemNode::all_controls_dominate
1124 // We find all controls of a pointer load, and see if they dominate the control of
1125 // an allocation. If they all dominate, we know the allocation is after (independent)
1126 // of the pointer load, and we can say the pointers are different. For this we call
1127 // n->dominates(sub, nlist) to check if controls n of the pointer load dominate the
1128 // control sub of the allocation. The problems is that sometimes dominates answers
1129 // false conservatively, and later it can determine that it is indeed true. Loops with
1130 // Region heads can lead to giving up, whereas LoopNodes can be skipped easier, and
1131 // so the traversal becomes more powerful. This is difficult to remidy, we would have
1132 // to notify the CmpP of CFG updates. Luckily, we recompute CmpP::Value during CCP
1133 // after loop-opts, so that should take care of many of these cases.
1134 return false;
1135 }
1136 tty->cr();
1137 tty->print_cr("Missed Value optimization:");
1138 n->dump_bfs(1, nullptr, "");
1139 tty->print_cr("Current type:");
1140 told->dump_on(tty);
1141 tty->cr();
1142 tty->print_cr("Optimized type:");
1143 tnew->dump_on(tty);
1144 tty->cr();
1145 return true;
1146 }
1147 #endif
1148
1149 /**
1150 * Register a new node with the optimizer. Update the types array, the def-use
1151 * info. Put on worklist.
1152 */
1153 Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
1154 set_type_bottom(n);
1155 _worklist.push(n);
1156 if (orig != nullptr) C->copy_node_notes_to(n, orig);
1157 return n;
1158 }
1159
1160 //------------------------------transform--------------------------------------
1161 // Non-recursive: idealize Node 'n' with respect to its inputs and its value
1162 Node *PhaseIterGVN::transform( Node *n ) {
1163 if (_delay_transform) {
1164 // Register the node but don't optimize for now
1165 register_new_node_with_optimizer(n);
1166 return n;
1167 }
1168
1169 // If brand new node, make space in type array, and give it a type.
1170 ensure_type_or_null(n);
1171 if (type_or_null(n) == nullptr) {
1172 set_type_bottom(n);
1173 }
1174
1175 return transform_old(n);
1176 }
1177
1178 Node *PhaseIterGVN::transform_old(Node* n) {
1179 NOT_PRODUCT(set_transforms());
1180 // Remove 'n' from hash table in case it gets modified
1181 _table.hash_delete(n);
1182 #ifdef ASSERT
1183 if (is_verify_def_use()) {
1184 assert(!_table.find_index(n->_idx), "found duplicate entry in table");
1185 }
1186 #endif
1187
1188 // Allow Bool -> Cmp idealisation in late inlining intrinsics that return a bool
1189 if (n->is_Cmp()) {
1190 add_users_to_worklist(n);
1191 }
1192
1193 // Apply the Ideal call in a loop until it no longer applies
1194 Node* k = n;
1195 DEBUG_ONLY(dead_loop_check(k);)
1196 DEBUG_ONLY(bool is_new = (k->outcnt() == 0);)
1197 C->remove_modified_node(k);
1198 Node* i = apply_ideal(k, /*can_reshape=*/true);
1199 assert(i != k || is_new || i->outcnt() > 0, "don't return dead nodes");
1200 #ifndef PRODUCT
1201 verify_step(k);
1202 #endif
1203
1204 DEBUG_ONLY(uint loop_count = 1;)
1205 while (i != nullptr) {
1206 #ifdef ASSERT
1207 if (loop_count >= K + C->live_nodes()) {
1208 dump_infinite_loop_info(i, "PhaseIterGVN::transform_old");
1209 }
1210 #endif
1211 assert((i->_idx >= k->_idx) || i->is_top(), "Idealize should return new nodes, use Identity to return old nodes");
1212 // Made a change; put users of original Node on worklist
1213 add_users_to_worklist(k);
1214 // Replacing root of transform tree?
1215 if (k != i) {
1216 // Make users of old Node now use new.
1217 subsume_node(k, i);
1218 k = i;
1219 }
1220 DEBUG_ONLY(dead_loop_check(k);)
1221 // Try idealizing again
1222 DEBUG_ONLY(is_new = (k->outcnt() == 0);)
1223 C->remove_modified_node(k);
1224 i = apply_ideal(k, /*can_reshape=*/true);
1225 assert(i != k || is_new || (i->outcnt() > 0), "don't return dead nodes");
1226 #ifndef PRODUCT
1227 verify_step(k);
1228 #endif
1229 DEBUG_ONLY(loop_count++;)
1230 }
1231
1232 // If brand new node, make space in type array.
1233 ensure_type_or_null(k);
1234
1235 // See what kind of values 'k' takes on at runtime
1236 const Type* t = k->Value(this);
1237 assert(t != nullptr, "value sanity");
1238
1239 // Since I just called 'Value' to compute the set of run-time values
1240 // for this Node, and 'Value' is non-local (and therefore expensive) I'll
1241 // cache Value. Later requests for the local phase->type of this Node can
1242 // use the cached Value instead of suffering with 'bottom_type'.
1243 if (type_or_null(k) != t) {
1244 #ifndef PRODUCT
1245 inc_new_values();
1246 set_progress();
1247 #endif
1248 set_type(k, t);
1249 // If k is a TypeNode, capture any more-precise type permanently into Node
1250 k->raise_bottom_type(t);
1251 // Move users of node to worklist
1252 add_users_to_worklist(k);
1253 }
1254 // If 'k' computes a constant, replace it with a constant
1255 if (t->singleton() && !k->is_Con()) {
1256 NOT_PRODUCT(set_progress();)
1257 Node* con = makecon(t); // Make a constant
1258 add_users_to_worklist(k);
1259 subsume_node(k, con); // Everybody using k now uses con
1260 return con;
1261 }
1262
1263 // Now check for Identities
1264 i = k->Identity(this); // Look for a nearby replacement
1265 if (i != k) { // Found? Return replacement!
1266 NOT_PRODUCT(set_progress();)
1267 add_users_to_worklist(k);
1268 subsume_node(k, i); // Everybody using k now uses i
1269 return i;
1270 }
1271
1272 // Global Value Numbering
1273 i = hash_find_insert(k); // Check for pre-existing node
1274 if (i && (i != k)) {
1275 // Return the pre-existing node if it isn't dead
1276 NOT_PRODUCT(set_progress();)
1277 add_users_to_worklist(k);
1278 subsume_node(k, i); // Everybody using k now uses i
1279 return i;
1280 }
1281
1282 // Return Idealized original
1283 return k;
1284 }
1285
1286 //---------------------------------saturate------------------------------------
1287 const Type* PhaseIterGVN::saturate(const Type* new_type, const Type* old_type,
1288 const Type* limit_type) const {
1289 return new_type->narrow(old_type);
1290 }
1291
1292 //------------------------------remove_globally_dead_node----------------------
1293 // Kill a globally dead Node. All uses are also globally dead and are
1294 // aggressively trimmed.
1295 void PhaseIterGVN::remove_globally_dead_node( Node *dead ) {
1296 enum DeleteProgress {
1297 PROCESS_INPUTS,
1298 PROCESS_OUTPUTS
1299 };
1300 ResourceMark rm;
1301 Node_Stack stack(32);
1302 stack.push(dead, PROCESS_INPUTS);
1303
1304 while (stack.is_nonempty()) {
1305 dead = stack.node();
1306 if (dead->Opcode() == Op_SafePoint) {
1307 dead->as_SafePoint()->disconnect_from_root(this);
1308 }
1309 uint progress_state = stack.index();
1310 assert(dead != C->root(), "killing root, eh?");
1311 assert(!dead->is_top(), "add check for top when pushing");
1312 NOT_PRODUCT( set_progress(); )
1313 if (progress_state == PROCESS_INPUTS) {
1314 // After following inputs, continue to outputs
1315 stack.set_index(PROCESS_OUTPUTS);
1316 if (!dead->is_Con()) { // Don't kill cons but uses
1317 bool recurse = false;
1318 // Remove from hash table
1319 _table.hash_delete( dead );
1320 // Smash all inputs to 'dead', isolating him completely
1321 for (uint i = 0; i < dead->req(); i++) {
1322 Node *in = dead->in(i);
1323 if (in != nullptr && in != C->top()) { // Points to something?
1324 int nrep = dead->replace_edge(in, nullptr, this); // Kill edges
1325 assert((nrep > 0), "sanity");
1326 if (in->outcnt() == 0) { // Made input go dead?
1327 stack.push(in, PROCESS_INPUTS); // Recursively remove
1328 recurse = true;
1329 } else if (in->outcnt() == 1 &&
1330 in->has_special_unique_user()) {
1331 _worklist.push(in->unique_out());
1332 } else if (in->outcnt() <= 2 && dead->is_Phi()) {
1333 if (in->Opcode() == Op_Region) {
1334 _worklist.push(in);
1335 } else if (in->is_Store()) {
1336 DUIterator_Fast imax, i = in->fast_outs(imax);
1337 _worklist.push(in->fast_out(i));
1338 i++;
1339 if (in->outcnt() == 2) {
1340 _worklist.push(in->fast_out(i));
1341 i++;
1342 }
1343 assert(!(i < imax), "sanity");
1344 }
1345 } else {
1346 BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(this, in);
1347 }
1348 if (ReduceFieldZeroing && dead->is_Load() && i == MemNode::Memory &&
1349 in->is_Proj() && in->in(0) != nullptr && in->in(0)->is_Initialize()) {
1350 // A Load that directly follows an InitializeNode is
1351 // going away. The Stores that follow are candidates
1352 // again to be captured by the InitializeNode.
1353 for (DUIterator_Fast jmax, j = in->fast_outs(jmax); j < jmax; j++) {
1354 Node *n = in->fast_out(j);
1355 if (n->is_Store()) {
1356 _worklist.push(n);
1357 }
1358 }
1359 }
1360 } // if (in != nullptr && in != C->top())
1361 } // for (uint i = 0; i < dead->req(); i++)
1362 if (recurse) {
1363 continue;
1364 }
1365 } // if (!dead->is_Con())
1366 } // if (progress_state == PROCESS_INPUTS)
1367
1368 // Aggressively kill globally dead uses
1369 // (Rather than pushing all the outs at once, we push one at a time,
1370 // plus the parent to resume later, because of the indefinite number
1371 // of edge deletions per loop trip.)
1372 if (dead->outcnt() > 0) {
1373 // Recursively remove output edges
1374 stack.push(dead->raw_out(0), PROCESS_INPUTS);
1375 } else {
1376 // Finished disconnecting all input and output edges.
1377 stack.pop();
1378 // Remove dead node from iterative worklist
1379 _worklist.remove(dead);
1380 C->remove_useless_node(dead);
1381 }
1382 } // while (stack.is_nonempty())
1383 }
1384
1385 //------------------------------subsume_node-----------------------------------
1386 // Remove users from node 'old' and add them to node 'nn'.
1387 void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
1388 if (old->Opcode() == Op_SafePoint) {
1389 old->as_SafePoint()->disconnect_from_root(this);
1390 }
1391 assert( old != hash_find(old), "should already been removed" );
1392 assert( old != C->top(), "cannot subsume top node");
1393 // Copy debug or profile information to the new version:
1394 C->copy_node_notes_to(nn, old);
1395 // Move users of node 'old' to node 'nn'
1396 for (DUIterator_Last imin, i = old->last_outs(imin); i >= imin; ) {
1397 Node* use = old->last_out(i); // for each use...
1398 // use might need re-hashing (but it won't if it's a new node)
1399 rehash_node_delayed(use);
1400 // Update use-def info as well
1401 // We remove all occurrences of old within use->in,
1402 // so as to avoid rehashing any node more than once.
1403 // The hash table probe swamps any outer loop overhead.
1404 uint num_edges = 0;
1405 for (uint jmax = use->len(), j = 0; j < jmax; j++) {
1406 if (use->in(j) == old) {
1407 use->set_req(j, nn);
1408 ++num_edges;
1409 }
1410 }
1411 i -= num_edges; // we deleted 1 or more copies of this edge
1412 }
1413
1414 // Search for instance field data PhiNodes in the same region pointing to the old
1415 // memory PhiNode and update their instance memory ids to point to the new node.
1416 if (old->is_Phi() && old->as_Phi()->type()->has_memory() && old->in(0) != nullptr) {
1417 Node* region = old->in(0);
1418 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1419 PhiNode* phi = region->fast_out(i)->isa_Phi();
1420 if (phi != nullptr && phi->inst_mem_id() == (int)old->_idx) {
1421 phi->set_inst_mem_id((int)nn->_idx);
1422 }
1423 }
1424 }
1425
1426 // Smash all inputs to 'old', isolating him completely
1427 Node *temp = new Node(1);
1428 temp->init_req(0,nn); // Add a use to nn to prevent him from dying
1429 remove_dead_node( old );
1430 temp->del_req(0); // Yank bogus edge
1431 if (nn != nullptr && nn->outcnt() == 0) {
1432 _worklist.push(nn);
1433 }
1434 #ifndef PRODUCT
1435 if (is_verify_def_use()) {
1436 for ( int i = 0; i < _verify_window_size; i++ ) {
1437 if ( _verify_window[i] == old )
1438 _verify_window[i] = nn;
1439 }
1440 }
1441 #endif
1442 temp->destruct(this); // reuse the _idx of this little guy
1443 }
1444
1445 //------------------------------add_users_to_worklist--------------------------
1446 void PhaseIterGVN::add_users_to_worklist0(Node* n, Unique_Node_List& worklist) {
1447 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1448 worklist.push(n->fast_out(i)); // Push on worklist
1449 }
1450 }
1451
1452 // Return counted loop Phi if as a counted loop exit condition, cmp
1453 // compares the induction variable with n
1454 static PhiNode* countedloop_phi_from_cmp(CmpNode* cmp, Node* n) {
1455 for (DUIterator_Fast imax, i = cmp->fast_outs(imax); i < imax; i++) {
1456 Node* bol = cmp->fast_out(i);
1457 for (DUIterator_Fast i2max, i2 = bol->fast_outs(i2max); i2 < i2max; i2++) {
1458 Node* iff = bol->fast_out(i2);
1459 if (iff->is_BaseCountedLoopEnd()) {
1460 BaseCountedLoopEndNode* cle = iff->as_BaseCountedLoopEnd();
1461 if (cle->limit() == n) {
1462 PhiNode* phi = cle->phi();
1463 if (phi != nullptr) {
1464 return phi;
1465 }
1466 }
1467 }
1468 }
1469 }
1470 return nullptr;
1471 }
1472
1473 void PhaseIterGVN::add_users_to_worklist(Node *n) {
1474 add_users_to_worklist0(n, _worklist);
1475
1476 Unique_Node_List& worklist = _worklist;
1477 // Move users of node to worklist
1478 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1479 Node* use = n->fast_out(i); // Get use
1480 add_users_of_use_to_worklist(n, use, worklist);
1481 }
1482 }
1483
1484 void PhaseIterGVN::add_users_of_use_to_worklist(Node* n, Node* use, Unique_Node_List& worklist) {
1485 if(use->is_Multi() || // Multi-definer? Push projs on worklist
1486 use->is_Store() ) // Enable store/load same address
1487 add_users_to_worklist0(use, worklist);
1488
1489 // If we changed the receiver type to a call, we need to revisit
1490 // the Catch following the call. It's looking for a non-null
1491 // receiver to know when to enable the regular fall-through path
1492 // in addition to the NullPtrException path.
1493 if (use->is_CallDynamicJava() && n == use->in(TypeFunc::Parms)) {
1494 Node* p = use->as_CallDynamicJava()->proj_out_or_null(TypeFunc::Control);
1495 if (p != nullptr) {
1496 add_users_to_worklist0(p, worklist);
1497 }
1498 }
1499
1500 uint use_op = use->Opcode();
1501 if(use->is_Cmp()) { // Enable CMP/BOOL optimization
1502 add_users_to_worklist0(use, worklist); // Put Bool on worklist
1503 if (use->outcnt() > 0) {
1504 Node* bol = use->raw_out(0);
1505 if (bol->outcnt() > 0) {
1506 Node* iff = bol->raw_out(0);
1507 if (iff->outcnt() == 2) {
1508 // Look for the 'is_x2logic' pattern: "x ? : 0 : 1" and put the
1509 // phi merging either 0 or 1 onto the worklist
1510 Node* ifproj0 = iff->raw_out(0);
1511 Node* ifproj1 = iff->raw_out(1);
1512 if (ifproj0->outcnt() > 0 && ifproj1->outcnt() > 0) {
1513 Node* region0 = ifproj0->raw_out(0);
1514 Node* region1 = ifproj1->raw_out(0);
1515 if( region0 == region1 )
1516 add_users_to_worklist0(region0, worklist);
1517 }
1518 }
1519 }
1520 }
1521 if (use_op == Op_CmpI || use_op == Op_CmpL) {
1522 Node* phi = countedloop_phi_from_cmp(use->as_Cmp(), n);
1523 if (phi != nullptr) {
1524 // Input to the cmp of a loop exit check has changed, thus
1525 // the loop limit may have changed, which can then change the
1526 // range values of the trip-count Phi.
1527 worklist.push(phi);
1528 }
1529 }
1530 if (use_op == Op_CmpI) {
1531 Node* cmp = use;
1532 Node* in1 = cmp->in(1);
1533 Node* in2 = cmp->in(2);
1534 // Notify CmpI / If pattern from CastIINode::Value (left pattern).
1535 // Must also notify if in1 is modified and possibly turns into X (right pattern).
1536 //
1537 // in1 in2 in1 in2
1538 // | | | |
1539 // +--- | --+ | |
1540 // | | | | |
1541 // CmpINode | CmpINode
1542 // | | |
1543 // BoolNode | BoolNode
1544 // | | OR |
1545 // IfNode | IfNode
1546 // | | |
1547 // IfProj | IfProj X
1548 // | | | |
1549 // CastIINode CastIINode
1550 //
1551 if (in1 != in2) { // if they are equal, the CmpI can fold them away
1552 if (in1 == n) {
1553 // in1 modified -> could turn into X -> do traversal based on right pattern.
1554 for (DUIterator_Fast i2max, i2 = cmp->fast_outs(i2max); i2 < i2max; i2++) {
1555 Node* bol = cmp->fast_out(i2); // For each Bool
1556 if (bol->is_Bool()) {
1557 for (DUIterator_Fast i3max, i3 = bol->fast_outs(i3max); i3 < i3max; i3++) {
1558 Node* iff = bol->fast_out(i3); // For each If
1559 if (iff->is_If()) {
1560 for (DUIterator_Fast i4max, i4 = iff->fast_outs(i4max); i4 < i4max; i4++) {
1561 Node* if_proj = iff->fast_out(i4); // For each IfProj
1562 assert(if_proj->is_IfProj(), "If only has IfTrue and IfFalse as outputs");
1563 for (DUIterator_Fast i5max, i5 = if_proj->fast_outs(i5max); i5 < i5max; i5++) {
1564 Node* castii = if_proj->fast_out(i5); // For each CastII
1565 if (castii->is_CastII() &&
1566 castii->as_CastII()->carry_dependency()) {
1567 worklist.push(castii);
1568 }
1569 }
1570 }
1571 }
1572 }
1573 }
1574 }
1575 } else {
1576 // Only in2 modified -> can assume X == in2 (left pattern).
1577 assert(n == in2, "only in2 modified");
1578 // Find all CastII with input in1.
1579 for (DUIterator_Fast jmax, j = in1->fast_outs(jmax); j < jmax; j++) {
1580 Node* castii = in1->fast_out(j);
1581 if (castii->is_CastII() && castii->as_CastII()->carry_dependency()) {
1582 // Find If.
1583 if (castii->in(0) != nullptr && castii->in(0)->in(0) != nullptr && castii->in(0)->in(0)->is_If()) {
1584 Node* ifnode = castii->in(0)->in(0);
1585 // Check that if connects to the cmp
1586 if (ifnode->in(1) != nullptr && ifnode->in(1)->is_Bool() && ifnode->in(1)->in(1) == cmp) {
1587 worklist.push(castii);
1588 }
1589 }
1590 }
1591 }
1592 }
1593 }
1594 }
1595 }
1596
1597 // If changed Cast input, notify down for Phi, Sub, and Xor - all do "uncast"
1598 // Patterns:
1599 // ConstraintCast+ -> Sub
1600 // ConstraintCast+ -> Phi
1601 // ConstraintCast+ -> Xor
1602 if (use->is_ConstraintCast()) {
1603 auto push_the_uses_to_worklist = [&](Node* n){
1604 if (n->is_Phi() || n->is_Sub() || n->Opcode() == Op_XorI || n->Opcode() == Op_XorL) {
1605 worklist.push(n);
1606 }
1607 };
1608 auto is_boundary = [](Node* n){ return !n->is_ConstraintCast(); };
1609 use->visit_uses(push_the_uses_to_worklist, is_boundary);
1610 }
1611 // If changed LShift inputs, check RShift users for useless sign-ext
1612 if( use_op == Op_LShiftI ) {
1613 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1614 Node* u = use->fast_out(i2);
1615 if (u->Opcode() == Op_RShiftI)
1616 worklist.push(u);
1617 }
1618 }
1619 // If changed LShift inputs, check And users for shift and mask (And) operation
1620 if (use_op == Op_LShiftI || use_op == Op_LShiftL) {
1621 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1622 Node* u = use->fast_out(i2);
1623 if (u->Opcode() == Op_AndI || u->Opcode() == Op_AndL) {
1624 worklist.push(u);
1625 }
1626 }
1627 }
1628 // If changed AddI/SubI inputs, check CmpU for range check optimization.
1629 if (use_op == Op_AddI || use_op == Op_SubI) {
1630 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1631 Node* u = use->fast_out(i2);
1632 if (u->is_Cmp() && (u->Opcode() == Op_CmpU)) {
1633 worklist.push(u);
1634 }
1635 }
1636 }
1637 // If changed AddP inputs, check Stores for loop invariant
1638 if( use_op == Op_AddP ) {
1639 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1640 Node* u = use->fast_out(i2);
1641 if (u->is_Mem())
1642 worklist.push(u);
1643 }
1644 }
1645 // If changed initialization activity, check dependent Stores
1646 if (use_op == Op_Allocate || use_op == Op_AllocateArray) {
1647 InitializeNode* init = use->as_Allocate()->initialization();
1648 if (init != nullptr) {
1649 Node* imem = init->proj_out_or_null(TypeFunc::Memory);
1650 if (imem != nullptr) add_users_to_worklist0(imem, worklist);
1651 }
1652 }
1653 // If the ValidLengthTest input changes then the fallthrough path out of the AllocateArray may have become dead.
1654 // CatchNode::Value() is responsible for killing that path. The CatchNode has to be explicitly enqueued for igvn
1655 // to guarantee the change is not missed.
1656 if (use_op == Op_AllocateArray && n == use->in(AllocateNode::ValidLengthTest)) {
1657 Node* p = use->as_AllocateArray()->proj_out_or_null(TypeFunc::Control);
1658 if (p != nullptr) {
1659 add_users_to_worklist0(p, worklist);
1660 }
1661 }
1662
1663 if (use_op == Op_Initialize) {
1664 Node* imem = use->as_Initialize()->proj_out_or_null(TypeFunc::Memory);
1665 if (imem != nullptr) add_users_to_worklist0(imem, worklist);
1666 }
1667 // Loading the java mirror from a Klass requires two loads and the type
1668 // of the mirror load depends on the type of 'n'. See LoadNode::Value().
1669 // LoadBarrier?(LoadP(LoadP(AddP(foo:Klass, #java_mirror))))
1670 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1671 bool has_load_barrier_nodes = bs->has_load_barrier_nodes();
1672
1673 if (use_op == Op_LoadP && use->bottom_type()->isa_rawptr()) {
1674 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1675 Node* u = use->fast_out(i2);
1676 const Type* ut = u->bottom_type();
1677 if (u->Opcode() == Op_LoadP && ut->isa_instptr()) {
1678 if (has_load_barrier_nodes) {
1679 // Search for load barriers behind the load
1680 for (DUIterator_Fast i3max, i3 = u->fast_outs(i3max); i3 < i3max; i3++) {
1681 Node* b = u->fast_out(i3);
1682 if (bs->is_gc_barrier_node(b)) {
1683 worklist.push(b);
1684 }
1685 }
1686 }
1687 worklist.push(u);
1688 }
1689 }
1690 }
1691 if (use->Opcode() == Op_OpaqueZeroTripGuard) {
1692 assert(use->outcnt() <= 1, "OpaqueZeroTripGuard can't be shared");
1693 if (use->outcnt() == 1) {
1694 Node* cmp = use->unique_out();
1695 worklist.push(cmp);
1696 }
1697 }
1698 if (use->Opcode() == Op_AddX) {
1699 for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
1700 Node* u = use->fast_out(i2);
1701 if (u->Opcode() == Op_CastX2P) {
1702 worklist.push(u);
1703 }
1704 }
1705 }
1706 }
1707
1708 /**
1709 * Remove the speculative part of all types that we know of
1710 */
1711 void PhaseIterGVN::remove_speculative_types() {
1712 assert(UseTypeSpeculation, "speculation is off");
1713 for (uint i = 0; i < _types.Size(); i++) {
1714 const Type* t = _types.fast_lookup(i);
1715 if (t != nullptr) {
1716 _types.map(i, t->remove_speculative());
1717 }
1718 }
1719 _table.check_no_speculative_types();
1720 }
1721
1722 // Check if the type of a divisor of a Div or Mod node includes zero.
1723 bool PhaseIterGVN::no_dependent_zero_check(Node* n) const {
1724 switch (n->Opcode()) {
1725 case Op_DivI:
1726 case Op_ModI: {
1727 // Type of divisor includes 0?
1728 if (type(n->in(2)) == Type::TOP) {
1729 // 'n' is dead. Treat as if zero check is still there to avoid any further optimizations.
1730 return false;
1731 }
1732 const TypeInt* type_divisor = type(n->in(2))->is_int();
1733 return (type_divisor->_hi < 0 || type_divisor->_lo > 0);
1734 }
1735 case Op_DivL:
1736 case Op_ModL: {
1737 // Type of divisor includes 0?
1738 if (type(n->in(2)) == Type::TOP) {
1739 // 'n' is dead. Treat as if zero check is still there to avoid any further optimizations.
1740 return false;
1741 }
1742 const TypeLong* type_divisor = type(n->in(2))->is_long();
1743 return (type_divisor->_hi < 0 || type_divisor->_lo > 0);
1744 }
1745 }
1746 return true;
1747 }
1748
1749 //=============================================================================
1750 #ifndef PRODUCT
1751 uint PhaseCCP::_total_invokes = 0;
1752 uint PhaseCCP::_total_constants = 0;
1753 #endif
1754 //------------------------------PhaseCCP---------------------------------------
1755 // Conditional Constant Propagation, ala Wegman & Zadeck
1756 PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
1757 NOT_PRODUCT( clear_constants(); )
1758 assert( _worklist.size() == 0, "" );
1759 analyze();
1760 }
1761
1762 #ifndef PRODUCT
1763 //------------------------------~PhaseCCP--------------------------------------
1764 PhaseCCP::~PhaseCCP() {
1765 inc_invokes();
1766 _total_constants += count_constants();
1767 }
1768 #endif
1769
1770
1771 #ifdef ASSERT
1772 void PhaseCCP::verify_type(Node* n, const Type* tnew, const Type* told) {
1773 if (tnew->meet(told) != tnew->remove_speculative()) {
1774 n->dump(1);
1775 tty->print("told = "); told->dump(); tty->cr();
1776 tty->print("tnew = "); tnew->dump(); tty->cr();
1777 fatal("Not monotonic");
1778 }
1779 assert(!told->isa_int() || !tnew->isa_int() || told->is_int()->_widen <= tnew->is_int()->_widen, "widen increases");
1780 assert(!told->isa_long() || !tnew->isa_long() || told->is_long()->_widen <= tnew->is_long()->_widen, "widen increases");
1781 }
1782 #endif //ASSERT
1783
1784 // In this analysis, all types are initially set to TOP. We iteratively call Value() on all nodes of the graph until
1785 // we reach a fixed-point (i.e. no types change anymore). We start with a list that only contains the root node. Each time
1786 // a new type is set, we push all uses of that node back to the worklist (in some cases, we also push grandchildren
1787 // or nodes even further down back to the worklist because their type could change as a result of the current type
1788 // change).
1789 void PhaseCCP::analyze() {
1790 // Initialize all types to TOP, optimistic analysis
1791 for (uint i = 0; i < C->unique(); i++) {
1792 _types.map(i, Type::TOP);
1793 }
1794
1795 // CCP worklist is placed on a local arena, so that we can allow ResourceMarks on "Compile::current()->resource_arena()".
1796 // We also do not want to put the worklist on "Compile::current()->comp_arena()", as that one only gets de-allocated after
1797 // Compile is over. The local arena gets de-allocated at the end of its scope.
1798 ResourceArea local_arena(mtCompiler);
1799 Unique_Node_List worklist(&local_arena);
1800 DEBUG_ONLY(Unique_Node_List worklist_verify(&local_arena);)
1801
1802 // Push root onto worklist
1803 worklist.push(C->root());
1804
1805 assert(_root_and_safepoints.size() == 0, "must be empty (unused)");
1806 _root_and_safepoints.push(C->root());
1807
1808 // Pull from worklist; compute new value; push changes out.
1809 // This loop is the meat of CCP.
1810 while (worklist.size() != 0) {
1811 Node* n = fetch_next_node(worklist);
1812 DEBUG_ONLY(worklist_verify.push(n);)
1813 if (n->is_SafePoint()) {
1814 // Make sure safepoints are processed by PhaseCCP::transform even if they are
1815 // not reachable from the bottom. Otherwise, infinite loops would be removed.
1816 _root_and_safepoints.push(n);
1817 }
1818 const Type* new_type = n->Value(this);
1819 if (new_type != type(n)) {
1820 DEBUG_ONLY(verify_type(n, new_type, type(n));)
1821 dump_type_and_node(n, new_type);
1822 set_type(n, new_type);
1823 push_child_nodes_to_worklist(worklist, n);
1824 }
1825 }
1826 DEBUG_ONLY(verify_analyze(worklist_verify);)
1827 }
1828
1829 #ifdef ASSERT
1830 // For every node n on verify list, check if type(n) == n->Value()
1831 // We have a list of exceptions, see comments in verify_node_value.
1832 void PhaseCCP::verify_analyze(Unique_Node_List& worklist_verify) {
1833 bool failure = false;
1834 while (worklist_verify.size()) {
1835 Node* n = worklist_verify.pop();
1836 failure |= verify_node_value(n);
1837 }
1838 // If we get this assert, check why the reported nodes were not processed again in CCP.
1839 // We should either make sure that these nodes are properly added back to the CCP worklist
1840 // in PhaseCCP::push_child_nodes_to_worklist() to update their type or add an exception
1841 // in the verification code above if that is not possible for some reason (like Load nodes).
1842 assert(!failure, "PhaseCCP not at fixpoint: analysis result may be unsound.");
1843 }
1844 #endif
1845
1846 // Fetch next node from worklist to be examined in this iteration.
1847 Node* PhaseCCP::fetch_next_node(Unique_Node_List& worklist) {
1848 if (StressCCP) {
1849 return worklist.remove(C->random() % worklist.size());
1850 } else {
1851 return worklist.pop();
1852 }
1853 }
1854
1855 #ifndef PRODUCT
1856 void PhaseCCP::dump_type_and_node(const Node* n, const Type* t) {
1857 if (TracePhaseCCP) {
1858 t->dump();
1859 do {
1860 tty->print("\t");
1861 } while (tty->position() < 16);
1862 n->dump();
1863 }
1864 }
1865 #endif
1866
1867 // We need to propagate the type change of 'n' to all its uses. Depending on the kind of node, additional nodes
1868 // (grandchildren or even further down) need to be revisited as their types could also be improved as a result
1869 // of the new type of 'n'. Push these nodes to the worklist.
1870 void PhaseCCP::push_child_nodes_to_worklist(Unique_Node_List& worklist, Node* n) const {
1871 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1872 Node* use = n->fast_out(i);
1873 push_if_not_bottom_type(worklist, use);
1874 push_more_uses(worklist, n, use);
1875 }
1876 }
1877
1878 void PhaseCCP::push_if_not_bottom_type(Unique_Node_List& worklist, Node* n) const {
1879 if (n->bottom_type() != type(n)) {
1880 worklist.push(n);
1881 }
1882 }
1883
1884 // For some nodes, we need to propagate the type change to grandchildren or even further down.
1885 // Add them back to the worklist.
1886 void PhaseCCP::push_more_uses(Unique_Node_List& worklist, Node* parent, const Node* use) const {
1887 push_phis(worklist, use);
1888 push_catch(worklist, use);
1889 push_cmpu(worklist, use);
1890 push_counted_loop_phi(worklist, parent, use);
1891 push_loadp(worklist, use);
1892 push_and(worklist, parent, use);
1893 push_cast_ii(worklist, parent, use);
1894 push_opaque_zero_trip_guard(worklist, use);
1895 }
1896
1897
1898 // We must recheck Phis too if use is a Region.
1899 void PhaseCCP::push_phis(Unique_Node_List& worklist, const Node* use) const {
1900 if (use->is_Region()) {
1901 for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1902 push_if_not_bottom_type(worklist, use->fast_out(i));
1903 }
1904 }
1905 }
1906
1907 // If we changed the receiver type to a call, we need to revisit the Catch node following the call. It's looking for a
1908 // non-null receiver to know when to enable the regular fall-through path in addition to the NullPtrException path.
1909 // Same is true if the type of a ValidLengthTest input to an AllocateArrayNode changes.
1910 void PhaseCCP::push_catch(Unique_Node_List& worklist, const Node* use) {
1911 if (use->is_Call()) {
1912 for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1913 Node* proj = use->fast_out(i);
1914 if (proj->is_Proj() && proj->as_Proj()->_con == TypeFunc::Control) {
1915 Node* catch_node = proj->find_out_with(Op_Catch);
1916 if (catch_node != nullptr) {
1917 worklist.push(catch_node);
1918 }
1919 }
1920 }
1921 }
1922 }
1923
1924 // CmpU nodes can get their type information from two nodes up in the graph (instead of from the nodes immediately
1925 // above). Make sure they are added to the worklist if nodes they depend on are updated since they could be missed
1926 // and get wrong types otherwise.
1927 void PhaseCCP::push_cmpu(Unique_Node_List& worklist, const Node* use) const {
1928 uint use_op = use->Opcode();
1929 if (use_op == Op_AddI || use_op == Op_SubI) {
1930 for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1931 Node* cmpu = use->fast_out(i);
1932 const uint cmpu_opcode = cmpu->Opcode();
1933 if (cmpu_opcode == Op_CmpU || cmpu_opcode == Op_CmpU3) {
1934 // Got a CmpU or CmpU3 which might need the new type information from node n.
1935 push_if_not_bottom_type(worklist, cmpu);
1936 }
1937 }
1938 }
1939 }
1940
1941 // If n is used in a counted loop exit condition, then the type of the counted loop's Phi depends on the type of 'n'.
1942 // Seem PhiNode::Value().
1943 void PhaseCCP::push_counted_loop_phi(Unique_Node_List& worklist, Node* parent, const Node* use) {
1944 uint use_op = use->Opcode();
1945 if (use_op == Op_CmpI || use_op == Op_CmpL) {
1946 PhiNode* phi = countedloop_phi_from_cmp(use->as_Cmp(), parent);
1947 if (phi != nullptr) {
1948 worklist.push(phi);
1949 }
1950 }
1951 }
1952
1953 // Loading the java mirror from a Klass requires two loads and the type of the mirror load depends on the type of 'n'.
1954 // See LoadNode::Value().
1955 void PhaseCCP::push_loadp(Unique_Node_List& worklist, const Node* use) const {
1956 BarrierSetC2* barrier_set = BarrierSet::barrier_set()->barrier_set_c2();
1957 bool has_load_barrier_nodes = barrier_set->has_load_barrier_nodes();
1958
1959 if (use->Opcode() == Op_LoadP && use->bottom_type()->isa_rawptr()) {
1960 for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1961 Node* loadp = use->fast_out(i);
1962 const Type* ut = loadp->bottom_type();
1963 if (loadp->Opcode() == Op_LoadP && ut->isa_instptr() && ut != type(loadp)) {
1964 if (has_load_barrier_nodes) {
1965 // Search for load barriers behind the load
1966 push_load_barrier(worklist, barrier_set, loadp);
1967 }
1968 worklist.push(loadp);
1969 }
1970 }
1971 }
1972 }
1973
1974 void PhaseCCP::push_load_barrier(Unique_Node_List& worklist, const BarrierSetC2* barrier_set, const Node* use) {
1975 for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1976 Node* barrier_node = use->fast_out(i);
1977 if (barrier_set->is_gc_barrier_node(barrier_node)) {
1978 worklist.push(barrier_node);
1979 }
1980 }
1981 }
1982
1983 // AndI/L::Value() optimizes patterns similar to (v << 2) & 3 to zero if they are bitwise disjoint.
1984 // Add the AndI/L nodes back to the worklist to re-apply Value() in case the shift value changed.
1985 // Pattern: parent -> LShift (use) -> (ConstraintCast | ConvI2L)* -> And
1986 void PhaseCCP::push_and(Unique_Node_List& worklist, const Node* parent, const Node* use) const {
1987 uint use_op = use->Opcode();
1988 if ((use_op == Op_LShiftI || use_op == Op_LShiftL)
1989 && use->in(2) == parent) { // is shift value (right-hand side of LShift)
1990 auto push_and_uses_to_worklist = [&](Node* n){
1991 uint opc = n->Opcode();
1992 if (opc == Op_AndI || opc == Op_AndL) {
1993 push_if_not_bottom_type(worklist, n);
1994 }
1995 };
1996 auto is_boundary = [](Node* n) {
1997 return !(n->is_ConstraintCast() || n->Opcode() == Op_ConvI2L);
1998 };
1999 use->visit_uses(push_and_uses_to_worklist, is_boundary);
2000 }
2001 }
2002
2003 // CastII::Value() optimizes CmpI/If patterns if the right input of the CmpI has a constant type. If the CastII input is
2004 // the same node as the left input into the CmpI node, the type of the CastII node can be improved accordingly. Add the
2005 // CastII node back to the worklist to re-apply Value() to either not miss this optimization or to undo it because it
2006 // cannot be applied anymore. We could have optimized the type of the CastII before but now the type of the right input
2007 // of the CmpI (i.e. 'parent') is no longer constant. The type of the CastII must be widened in this case.
2008 void PhaseCCP::push_cast_ii(Unique_Node_List& worklist, const Node* parent, const Node* use) const {
2009 if (use->Opcode() == Op_CmpI && use->in(2) == parent) {
2010 Node* other_cmp_input = use->in(1);
2011 for (DUIterator_Fast imax, i = other_cmp_input->fast_outs(imax); i < imax; i++) {
2012 Node* cast_ii = other_cmp_input->fast_out(i);
2013 if (cast_ii->is_CastII()) {
2014 push_if_not_bottom_type(worklist, cast_ii);
2015 }
2016 }
2017 }
2018 }
2019
2020 void PhaseCCP::push_opaque_zero_trip_guard(Unique_Node_List& worklist, const Node* use) const {
2021 if (use->Opcode() == Op_OpaqueZeroTripGuard) {
2022 push_if_not_bottom_type(worklist, use->unique_out());
2023 }
2024 }
2025
2026 //------------------------------do_transform-----------------------------------
2027 // Top level driver for the recursive transformer
2028 void PhaseCCP::do_transform() {
2029 // Correct leaves of new-space Nodes; they point to old-space.
2030 C->set_root( transform(C->root())->as_Root() );
2031 assert( C->top(), "missing TOP node" );
2032 assert( C->root(), "missing root" );
2033 }
2034
2035 //------------------------------transform--------------------------------------
2036 // Given a Node in old-space, clone him into new-space.
2037 // Convert any of his old-space children into new-space children.
2038 Node *PhaseCCP::transform( Node *n ) {
2039 assert(n->is_Root(), "traversal must start at root");
2040 assert(_root_and_safepoints.member(n), "root (n) must be in list");
2041
2042 ResourceMark rm;
2043 // Map: old node idx -> node after CCP (or nullptr if not yet transformed or useless).
2044 Node_List node_map;
2045 // Pre-allocate to avoid frequent realloc
2046 GrowableArray <Node *> transform_stack(C->live_nodes() >> 1);
2047 // track all visited nodes, so that we can remove the complement
2048 Unique_Node_List useful;
2049
2050 // Initialize the traversal.
2051 // This CCP pass may prove that no exit test for a loop ever succeeds (i.e. the loop is infinite). In that case,
2052 // the logic below doesn't follow any path from Root to the loop body: there's at least one such path but it's proven
2053 // never taken (its type is TOP). As a consequence the node on the exit path that's input to Root (let's call it n) is
2054 // replaced by the top node and the inputs of that node n are not enqueued for further processing. If CCP only works
2055 // through the graph from Root, this causes the loop body to never be processed here even when it's not dead (that
2056 // is reachable from Root following its uses). To prevent that issue, transform() starts walking the graph from Root
2057 // and all safepoints.
2058 for (uint i = 0; i < _root_and_safepoints.size(); ++i) {
2059 Node* nn = _root_and_safepoints.at(i);
2060 Node* new_node = node_map[nn->_idx];
2061 assert(new_node == nullptr, "");
2062 new_node = transform_once(nn); // Check for constant
2063 node_map.map(nn->_idx, new_node); // Flag as having been cloned
2064 transform_stack.push(new_node); // Process children of cloned node
2065 useful.push(new_node);
2066 }
2067
2068 while (transform_stack.is_nonempty()) {
2069 Node* clone = transform_stack.pop();
2070 uint cnt = clone->req();
2071 for( uint i = 0; i < cnt; i++ ) { // For all inputs do
2072 Node *input = clone->in(i);
2073 if( input != nullptr ) { // Ignore nulls
2074 Node *new_input = node_map[input->_idx]; // Check for cloned input node
2075 if( new_input == nullptr ) {
2076 new_input = transform_once(input); // Check for constant
2077 node_map.map( input->_idx, new_input );// Flag as having been cloned
2078 transform_stack.push(new_input); // Process children of cloned node
2079 useful.push(new_input);
2080 }
2081 assert( new_input == clone->in(i), "insanity check");
2082 }
2083 }
2084 }
2085
2086 // The above transformation might lead to subgraphs becoming unreachable from the
2087 // bottom while still being reachable from the top. As a result, nodes in that
2088 // subgraph are not transformed and their bottom types are not updated, leading to
2089 // an inconsistency between bottom_type() and type(). In rare cases, LoadNodes in
2090 // such a subgraph, might be re-enqueued for IGVN indefinitely by MemNode::Ideal_common
2091 // because their address type is inconsistent. Therefore, we aggressively remove
2092 // all useless nodes here even before PhaseIdealLoop::build_loop_late gets a chance
2093 // to remove them anyway.
2094 if (C->cached_top_node()) {
2095 useful.push(C->cached_top_node());
2096 }
2097 C->update_dead_node_list(useful);
2098 remove_useless_nodes(useful.member_set());
2099 _worklist.remove_useless_nodes(useful.member_set());
2100 C->disconnect_useless_nodes(useful, _worklist);
2101
2102 Node* new_root = node_map[n->_idx];
2103 assert(new_root->is_Root(), "transformed root node must be a root node");
2104 return new_root;
2105 }
2106
2107 //------------------------------transform_once---------------------------------
2108 // For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
2109 Node *PhaseCCP::transform_once( Node *n ) {
2110 const Type *t = type(n);
2111 // Constant? Use constant Node instead
2112 if( t->singleton() ) {
2113 Node *nn = n; // Default is to return the original constant
2114 if( t == Type::TOP ) {
2115 // cache my top node on the Compile instance
2116 if( C->cached_top_node() == nullptr || C->cached_top_node()->in(0) == nullptr ) {
2117 C->set_cached_top_node(ConNode::make(Type::TOP));
2118 set_type(C->top(), Type::TOP);
2119 }
2120 nn = C->top();
2121 }
2122 if( !n->is_Con() ) {
2123 if( t != Type::TOP ) {
2124 nn = makecon(t); // ConNode::make(t);
2125 NOT_PRODUCT( inc_constants(); )
2126 } else if( n->is_Region() ) { // Unreachable region
2127 // Note: nn == C->top()
2128 n->set_req(0, nullptr); // Cut selfreference
2129 bool progress = true;
2130 uint max = n->outcnt();
2131 DUIterator i;
2132 while (progress) {
2133 progress = false;
2134 // Eagerly remove dead phis to avoid phis copies creation.
2135 for (i = n->outs(); n->has_out(i); i++) {
2136 Node* m = n->out(i);
2137 if (m->is_Phi()) {
2138 assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
2139 replace_node(m, nn);
2140 if (max != n->outcnt()) {
2141 progress = true;
2142 i = n->refresh_out_pos(i);
2143 max = n->outcnt();
2144 }
2145 }
2146 }
2147 }
2148 }
2149 replace_node(n,nn); // Update DefUse edges for new constant
2150 }
2151 return nn;
2152 }
2153
2154 // If x is a TypeNode, capture any more-precise type permanently into Node
2155 if (t != n->bottom_type()) {
2156 hash_delete(n); // changing bottom type may force a rehash
2157 n->raise_bottom_type(t);
2158 _worklist.push(n); // n re-enters the hash table via the worklist
2159 }
2160
2161 // TEMPORARY fix to ensure that 2nd GVN pass eliminates null checks
2162 switch( n->Opcode() ) {
2163 case Op_CallStaticJava: // Give post-parse call devirtualization a chance
2164 case Op_CallDynamicJava:
2165 case Op_FastLock: // Revisit FastLocks for lock coarsening
2166 case Op_If:
2167 case Op_CountedLoopEnd:
2168 case Op_Region:
2169 case Op_Loop:
2170 case Op_CountedLoop:
2171 case Op_Conv2B:
2172 case Op_Opaque1:
2173 _worklist.push(n);
2174 break;
2175 default:
2176 break;
2177 }
2178
2179 return n;
2180 }
2181
2182 //---------------------------------saturate------------------------------------
2183 const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
2184 const Type* limit_type) const {
2185 const Type* wide_type = new_type->widen(old_type, limit_type);
2186 if (wide_type != new_type) { // did we widen?
2187 // If so, we may have widened beyond the limit type. Clip it back down.
2188 new_type = wide_type->filter(limit_type);
2189 }
2190 return new_type;
2191 }
2192
2193 //------------------------------print_statistics-------------------------------
2194 #ifndef PRODUCT
2195 void PhaseCCP::print_statistics() {
2196 tty->print_cr("CCP: %d constants found: %d", _total_invokes, _total_constants);
2197 }
2198 #endif
2199
2200
2201 //=============================================================================
2202 #ifndef PRODUCT
2203 uint PhasePeephole::_total_peepholes = 0;
2204 #endif
2205 //------------------------------PhasePeephole----------------------------------
2206 // Conditional Constant Propagation, ala Wegman & Zadeck
2207 PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
2208 : PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
2209 NOT_PRODUCT( clear_peepholes(); )
2210 }
2211
2212 #ifndef PRODUCT
2213 //------------------------------~PhasePeephole---------------------------------
2214 PhasePeephole::~PhasePeephole() {
2215 _total_peepholes += count_peepholes();
2216 }
2217 #endif
2218
2219 //------------------------------transform--------------------------------------
2220 Node *PhasePeephole::transform( Node *n ) {
2221 ShouldNotCallThis();
2222 return nullptr;
2223 }
2224
2225 //------------------------------do_transform-----------------------------------
2226 void PhasePeephole::do_transform() {
2227 bool method_name_not_printed = true;
2228
2229 // Examine each basic block
2230 for (uint block_number = 1; block_number < _cfg.number_of_blocks(); ++block_number) {
2231 Block* block = _cfg.get_block(block_number);
2232 bool block_not_printed = true;
2233
2234 for (bool progress = true; progress;) {
2235 progress = false;
2236 // block->end_idx() not valid after PhaseRegAlloc
2237 uint end_index = block->number_of_nodes();
2238 for( uint instruction_index = end_index - 1; instruction_index > 0; --instruction_index ) {
2239 Node *n = block->get_node(instruction_index);
2240 if( n->is_Mach() ) {
2241 MachNode *m = n->as_Mach();
2242 // check for peephole opportunities
2243 int result = m->peephole(block, instruction_index, &_cfg, _regalloc);
2244 if( result != -1 ) {
2245 #ifndef PRODUCT
2246 if( PrintOptoPeephole ) {
2247 // Print method, first time only
2248 if( C->method() && method_name_not_printed ) {
2249 C->method()->print_short_name(); tty->cr();
2250 method_name_not_printed = false;
2251 }
2252 // Print this block
2253 if( Verbose && block_not_printed) {
2254 tty->print_cr("in block");
2255 block->dump();
2256 block_not_printed = false;
2257 }
2258 // Print the peephole number
2259 tty->print_cr("peephole number: %d", result);
2260 }
2261 inc_peepholes();
2262 #endif
2263 // Set progress, start again
2264 progress = true;
2265 break;
2266 }
2267 }
2268 }
2269 }
2270 }
2271 }
2272
2273 //------------------------------print_statistics-------------------------------
2274 #ifndef PRODUCT
2275 void PhasePeephole::print_statistics() {
2276 tty->print_cr("Peephole: peephole rules applied: %d", _total_peepholes);
2277 }
2278 #endif
2279
2280
2281 //=============================================================================
2282 //------------------------------set_req_X--------------------------------------
2283 void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
2284 assert( is_not_dead(n), "can not use dead node");
2285 #ifdef ASSERT
2286 if (igvn->hash_find(this) == this) {
2287 tty->print_cr("Need to remove from hash before changing edges");
2288 this->dump(1);
2289 tty->print_cr("Set at i = %d", i);
2290 n->dump();
2291 assert(false, "Need to remove from hash before changing edges");
2292 }
2293 #endif
2294 Node *old = in(i);
2295 set_req(i, n);
2296
2297 // old goes dead?
2298 if( old ) {
2299 switch (old->outcnt()) {
2300 case 0:
2301 // Put into the worklist to kill later. We do not kill it now because the
2302 // recursive kill will delete the current node (this) if dead-loop exists
2303 if (!old->is_top())
2304 igvn->_worklist.push( old );
2305 break;
2306 case 1:
2307 if( old->is_Store() || old->has_special_unique_user() )
2308 igvn->add_users_to_worklist( old );
2309 break;
2310 case 2:
2311 if( old->is_Store() )
2312 igvn->add_users_to_worklist( old );
2313 if( old->Opcode() == Op_Region )
2314 igvn->_worklist.push(old);
2315 break;
2316 case 3:
2317 if( old->Opcode() == Op_Region ) {
2318 igvn->_worklist.push(old);
2319 igvn->add_users_to_worklist( old );
2320 }
2321 break;
2322 default:
2323 break;
2324 }
2325
2326 BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, old);
2327 }
2328 }
2329
2330 void Node::set_req_X(uint i, Node *n, PhaseGVN *gvn) {
2331 PhaseIterGVN* igvn = gvn->is_IterGVN();
2332 if (igvn == nullptr) {
2333 set_req(i, n);
2334 return;
2335 }
2336 set_req_X(i, n, igvn);
2337 }
2338
2339 //-------------------------------replace_by-----------------------------------
2340 // Using def-use info, replace one node for another. Follow the def-use info
2341 // to all users of the OLD node. Then make all uses point to the NEW node.
2342 void Node::replace_by(Node *new_node) {
2343 assert(!is_top(), "top node has no DU info");
2344 for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
2345 Node* use = last_out(i);
2346 uint uses_found = 0;
2347 for (uint j = 0; j < use->len(); j++) {
2348 if (use->in(j) == this) {
2349 if (j < use->req())
2350 use->set_req(j, new_node);
2351 else use->set_prec(j, new_node);
2352 uses_found++;
2353 }
2354 }
2355 i -= uses_found; // we deleted 1 or more copies of this edge
2356 }
2357 }
2358
2359 //=============================================================================
2360 //-----------------------------------------------------------------------------
2361 void Type_Array::grow( uint i ) {
2362 assert(_a == Compile::current()->comp_arena(), "Should be allocated in comp_arena");
2363 if( !_max ) {
2364 _max = 1;
2365 _types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
2366 _types[0] = nullptr;
2367 }
2368 uint old = _max;
2369 _max = next_power_of_2(i);
2370 _types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
2371 memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
2372 }
2373
2374 //------------------------------dump-------------------------------------------
2375 #ifndef PRODUCT
2376 void Type_Array::dump() const {
2377 uint max = Size();
2378 for( uint i = 0; i < max; i++ ) {
2379 if( _types[i] != nullptr ) {
2380 tty->print(" %d\t== ", i); _types[i]->dump(); tty->cr();
2381 }
2382 }
2383 }
2384 #endif