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.
5
* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
9
* This code is distributed in the hope that it will be useful, but WITHOUT
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* 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).
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.
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
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"
44
//=============================================================================
45
#define NODE_HASH_MINIMUM_SIZE 255
47
//------------------------------NodeHash---------------------------------------
48
NodeHash::NodeHash(Arena *arena, uint est_max_size) :
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 ) )
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)
59
// _sentinel must be in the current node space
60
_sentinel = new ProjNode(nullptr, TypeFunc::Control);
61
memset(_table,0,sizeof(Node*)*_max);
64
//------------------------------hash_find--------------------------------------
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++ );
73
uint key = hash & (_max-1);
74
uint stride = key | 0x01;
75
NOT_PRODUCT( _look_probes++ );
76
Node *k = _table[key]; // Get hashed value
78
NOT_PRODUCT( _lookup_misses++ );
79
return nullptr; // Miss!
84
while( 1 ) { // While probing hash table
85
if( k->req() == req && // Same count of inputs
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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++ );
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
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NOT_PRODUCT( _lookup_misses++ );
101
return nullptr; // Miss!
104
ShouldNotReachHere();
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 ) {
113
uint hash = n->hash();
114
if (hash == Node::NO_HASH) {
115
NOT_PRODUCT( _lookup_misses++ );
118
uint key = hash & (_max-1);
119
uint stride = key | 0x01; // stride must be relatively prime to table siz
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uint first_sentinel = 0; // replace a sentinel if seen.
121
NOT_PRODUCT( _look_probes++ );
122
Node *k = _table[key]; // Get hashed value
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NOT_PRODUCT( _lookup_misses++ );
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_table[key] = n; // Insert into table!
126
debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
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check_grow(); // Grow table if insert hit limit
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return nullptr; // Miss!
130
else if( k == _sentinel ) {
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first_sentinel = key; // Can insert here
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int op = n->Opcode();
136
while( 1 ) { // While probing hash table
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if( k->req() == req && // Same count of inputs
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k->Opcode() == op ) { // Same Opcode
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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...
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if( n->cmp(*k) ) { // Check for any special bits
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NOT_PRODUCT( _lookup_hits++ );
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NOT_PRODUCT( _look_probes++ );
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key = (key + stride) & (_max-1); // Stride through table w/ relative prime
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k = _table[key]; // Get hashed value
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NOT_PRODUCT( _lookup_misses++ );
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key = (first_sentinel == 0) ? key : first_sentinel; // ?saw sentinel?
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_table[key] = n; // Insert into table!
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debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
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check_grow(); // Grow table if insert hit limit
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return nullptr; // Miss!
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else if( first_sentinel == 0 && k == _sentinel ) {
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first_sentinel = key; // Can insert here
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ShouldNotReachHere();
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//------------------------------hash_insert------------------------------------
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// Insert into hash table
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void NodeHash::hash_insert( Node *n ) {
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// // "conflict" comments -- print nodes that conflict
172
// bool conflict = false;
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uint hash = n->hash();
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if (hash == Node::NO_HASH) {
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uint key = hash & (_max-1);
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uint stride = key | 0x01;
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while( 1 ) { // While probing hash table
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NOT_PRODUCT( _insert_probes++ );
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Node *k = _table[key]; // Get hashed value
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if( !k || (k == _sentinel) ) break; // Found a slot
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assert( k != n, "already inserted" );
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// if( PrintCompilation && PrintOptoStatistics && Verbose ) { tty->print(" conflict: "); k->dump(); conflict = true; }
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key = (key + stride) & (_max-1); // Stride through table w/ relative prime
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_table[key] = n; // Insert into table!
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debug_only(n->enter_hash_lock()); // Lock down the node while in the table.
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// if( conflict ) { n->dump(); }
195
//------------------------------hash_delete------------------------------------
196
// Replace in hash table with sentinel
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bool NodeHash::hash_delete( const Node *n ) {
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uint hash = n->hash();
200
if (hash == Node::NO_HASH) {
201
NOT_PRODUCT( _delete_misses++ );
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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
212
NOT_PRODUCT( _delete_misses++ );
213
return false; // Miss! Not in chain
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.
222
// collision: move through table with prime offset
223
key = (key + stride/*7*/) & (_max-1);
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assert( counter <= _insert_limit, "Cycle in hash-table");
227
ShouldNotReachHere();
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));
238
//------------------------------grow-------------------------------------------
239
// Grow _table to next power of 2 and insert old entries
240
void NodeHash::grow() {
243
Node **old_table = _table;
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// Construct new table with twice the space
247
_total_inserts += _inserts;
248
_total_insert_probes += _insert_probes;
253
_table = NEW_ARENA_ARRAY( _a , Node* , _max ); // (Node**)_a->Amalloc( _max * sizeof(Node*) );
254
memset(_table,0,sizeof(Node*)*_max);
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_insert_limit = insert_limit();
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// 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.
265
//------------------------------clear------------------------------------------
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// Clear all entries in _table to null but keep storage
267
void NodeHash::clear() {
269
// Unlock all nodes upon removal from table.
270
for (uint i = 0; i < _max; i++) {
272
if (!n || n == _sentinel) continue;
277
memset( _table, 0, _max * sizeof(Node*) );
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) {
285
// Dead nodes in the hash table inherited from GVN should not replace
286
// existing nodes, remove dead nodes.
288
Node *sentinel_node = sentinel();
289
for( uint i = 0; i < max; ++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
299
void NodeHash::check_no_speculative_types() {
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) {
308
n != sentinel_node &&
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");
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)) {
328
for (uint i=0; i<_max; i++) {
330
tty->print("%d/%d/%d ",i,_table[i]->hash()&(_max-1),_table[i]->_idx);
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tty->print("\nGVN Hash stats: %d grows to %d max_size\n", _grows, _max);
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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" );
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++ ) {
348
if( !m || m == _sentinel ) continue;
349
if( m->_idx == (uint)idx ) return m;
356
NodeHash::~NodeHash() {
357
// Unlock all nodes upon destruction of table.
358
if (_table != (Node**)badAddress) clear();
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().
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);
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());
380
// Remove all useless nodes from future worklist
381
worklist.remove_useless_nodes(_useful.member_set());
383
// Disconnect 'useless' nodes that are adjacent to useful nodes
384
C->disconnect_useless_nodes(_useful, worklist);
387
//=============================================================================
388
//------------------------------PhaseRenumberLive------------------------------
389
// First, remove useless nodes (equivalent to identifying live nodes).
390
// Then, renumber live nodes.
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).
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).
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.
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())
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");
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);
433
assert(worklist.is_subset_of(_useful), "only useful nodes should still be in the worklist");
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);
439
const Type* type = gvn->type_or_null(n);
440
_new_type_array.map(current_idx, type);
442
assert(_old2new_map.at(n->_idx) == -1, "already seen");
443
_old2new_map.at_put(n->_idx, current_idx);
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);
450
n->set_idx(current_idx); // Update node ID.
452
if (update_embedded_ids(n) < 0) {
453
_delayed.push(n); // has embedded IDs; handle later
457
// VectorSet in Unique_Node_Set must be recomputed, since IDs have changed.
458
worklist.recompute_idx_set();
460
assert(_live_node_count == _useful.size(), "all live nodes must be processed");
462
_is_pass_finished = true; // pass finished; safe to process delayed updates
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");
470
// Replace the compiler's type information with the updated type information.
471
gvn->types().swap(_new_type_array);
473
// Update the unique node count of the compilation to the number of currently live nodes.
474
C->set_unique(_live_node_count);
476
// Set the dead node count to 0 and reset dead node list.
477
C->reset_dead_node_list();
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);
487
return _old2new_map.at(old_idx);
490
int PhaseRenumberLive::update_embedded_ids(Node* n) {
491
int no_of_updates = 0;
493
PhiNode* phi = n->as_Phi();
494
if (phi->_inst_id != -1) {
495
if (!_is_pass_finished) {
498
int new_idx = new_index(phi->_inst_id);
499
assert(new_idx != -1, "");
500
phi->_inst_id = new_idx;
503
if (phi->_inst_mem_id != -1) {
504
if (!_is_pass_finished) {
507
int new_idx = new_index(phi->_inst_mem_id);
508
assert(new_idx != -1, "");
509
phi->_inst_mem_id = new_idx;
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) {
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);
526
return no_of_updates;
529
void PhaseValues::init_con_caches() {
530
memset(_icons,0,sizeof(_icons));
531
memset(_lcons,0,sizeof(_lcons));
532
memset(_zcons,0,sizeof(_zcons));
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;
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();
556
//------------------------------~PhaseValues-----------------------------------
558
PhaseValues::~PhaseValues() {
559
// Statistics for NodeHash
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() );
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
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() );
585
if (t->is_zero_type())
586
return zerocon(t->basic_type());
587
return uncached_makecon(t);
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
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
604
x->destruct(this); // Hit, destroy duplicate constant
605
x = k; // use existing constant
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)
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
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)
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
641
ConNode* PhaseValues::integercon(jlong l, BasicType bt) {
643
return intcon(checked_cast<jint>(l));
645
assert(bt == T_LONG, "not an integer");
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)
657
zcon = (ConNode*) uncached_makecon(Type::get_zero_type(bt));
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);
668
i = k->Ideal(this, can_reshape);
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(); )
679
// Apply the Ideal call in a loop until it no longer applies
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" );
687
if (loop_count >= K + C->live_nodes()) {
688
dump_infinite_loop_info(i, "PhaseGVN::transform");
691
i = apply_ideal(k, /*can_reshape=*/false);
692
NOT_PRODUCT(loop_count++;)
694
NOT_PRODUCT(if (loop_count != 0) { set_progress(); })
696
// If brand new node, make space in type array.
697
ensure_type_or_null(k);
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) {
707
// Do not count initial visit to node as a transformation
708
if (type_or_null(k) == nullptr) {
714
// If k is a TypeNode, capture any more-precise type permanently into Node
715
k->raise_bottom_type(t);
718
if (t->singleton() && !k->is_Con()) {
719
NOT_PRODUCT(set_progress();)
720
return makecon(t); // Turn into a constant
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();)
730
// Global Value Numbering
731
i = hash_find_insert(k); // Insert if new
733
// Return the pre-existing node
734
NOT_PRODUCT(set_progress();)
738
// Return Idealized original
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())) {
746
if (n->is_top() || (n->is_Proj() && n->in(0)->is_top())) {
749
assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
752
n = IfNode::up_one_dom(n, linear_only);
754
if (n == nullptr || i >= 100) {
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;
771
for (uint i = 1; i < cnt && no_dead_loop; i++) {
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;
783
if (!no_dead_loop) n->dump_bfs(100,nullptr,"#");
784
assert(no_dead_loop, "dead loop detected");
790
* Dumps information that can help to debug the problem. A debug
791
* build fails with an assert.
793
void PhaseGVN::dump_infinite_loop_info(Node* n, const char* where) {
795
assert(false, "infinite loop in %s", where);
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())
806
assert(&_worklist == &igvn->_worklist, "sanity");
809
//------------------------------PhaseIterGVN-----------------------------------
810
// Initialize with previous PhaseGVN info from Parser
811
PhaseIterGVN::PhaseIterGVN(PhaseGVN* gvn) : _delay_transform(false),
812
_worklist(*C->igvn_worklist())
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.
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");
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 ||
841
add_users_to_worklist(n);
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]);
854
void PhaseIterGVN::verify_step(Node* n) {
855
if (is_verify_def_use()) {
860
_verify_window[_verify_counter % _verify_window_size] = n;
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);
868
for (int i = 0; i < _verify_window_size; i++) {
869
Node* n = _verify_window[i];
873
if (n->in(0) == NodeSentinel) { // xform_idom
874
_verify_window[i] = n->in(1);
878
// Typical fanout is 1-2, so this call visits about 6 nodes.
879
if (!visited.test_set(n->_idx)) {
883
Node::verify(4, visited, worklist);
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);
892
if (TraceIterativeGVN) {
893
uint wlsize = _worklist.size();
897
if (oldtype != newtype && oldtype != nullptr) {
900
do { tty->print("\t"); } while (tty->position() < 16);
904
if (oldtype != newtype || nn != n) {
905
// print new node and/or new type
906
if (oldtype == nullptr) {
908
} else if (nn != n) {
913
if (newtype == nullptr) {
918
do { tty->print("\t"); } while (tty->position() < 16);
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);
930
// ignore n, it might be subsumed
931
verify_step((Node*) nullptr);
936
void PhaseIterGVN::init_verifyPhaseIterGVN() {
938
_verify_full_passes = 0;
939
for (int i = 0; i < _verify_window_size; i++) {
940
_verify_window[i] = nullptr;
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)) {
949
fatal("modified node is not on IGVN._worklist");
955
void PhaseIterGVN::verify_PhaseIterGVN() {
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
963
fatal("modified node was not processed by IGVN.transform_old()");
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);
974
tty->print_cr("VerifyIterativeGVN: %d transforms, %d full verify passes",
975
(int) _verify_counter, (int) _verify_full_passes);
980
if (modified_list != nullptr) {
981
while (modified_list->size() > 0) {
982
Node* n = modified_list->pop();
984
assert(false, "VerifyIterativeGVN: new modified node was added");
995
* Dumps information that can help to debug the problem. A debug
996
* build fails with an assert.
998
void PhaseIterGVN::dump_infinite_loop_info(Node* n, const char* where) {
1001
assert(false, "infinite loop in %s", where);
1005
* Prints out information about IGVN if the 'verbose' option is used.
1007
void PhaseIterGVN::trace_PhaseIterGVN_verbose(Node* n, int num_processed) {
1008
if (TraceIterativeGVN && Verbose) {
1009
tty->print(" Pop ");
1011
if ((num_processed % 100) == 0) {
1012
_worklist.print_set();
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);
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);
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);
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);
1053
NOT_PRODUCT(verify_PhaseIterGVN();)
1054
C->print_method(PHASE_AFTER_ITER_GVN, 3);
1058
void PhaseIterGVN::verify_optimize() {
1059
if (is_verify_Value()) {
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));
1074
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1075
worklist.push(n->fast_out(i));
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");
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);
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
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.
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()) {
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.
1137
tty->print_cr("Missed Value optimization:");
1138
n->dump_bfs(1, nullptr, "");
1139
tty->print_cr("Current type:");
1142
tty->print_cr("Optimized type:");
1150
* Register a new node with the optimizer. Update the types array, the def-use
1151
* info. Put on worklist.
1153
Node* PhaseIterGVN::register_new_node_with_optimizer(Node* n, Node* orig) {
1156
if (orig != nullptr) C->copy_node_notes_to(n, orig);
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);
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) {
1175
return transform_old(n);
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);
1183
if (is_verify_def_use()) {
1184
assert(!_table.find_index(n->_idx), "found duplicate entry in table");
1188
// Allow Bool -> Cmp idealisation in late inlining intrinsics that return a bool
1190
add_users_to_worklist(n);
1193
// Apply the Ideal call in a loop until it no longer applies
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");
1204
DEBUG_ONLY(uint loop_count = 1;)
1205
while (i != nullptr) {
1207
if (loop_count >= K + C->live_nodes()) {
1208
dump_infinite_loop_info(i, "PhaseIterGVN::transform_old");
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?
1216
// Make users of old Node now use new.
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");
1229
DEBUG_ONLY(loop_count++;)
1232
// If brand new node, make space in type array.
1233
ensure_type_or_null(k);
1235
// See what kind of values 'k' takes on at runtime
1236
const Type* t = k->Value(this);
1237
assert(t != nullptr, "value sanity");
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) {
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);
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
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
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
1282
// Return Idealized original
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);
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 {
1301
Node_Stack stack(32);
1302
stack.push(dead, PROCESS_INPUTS);
1304
while (stack.is_nonempty()) {
1305
dead = stack.node();
1306
if (dead->Opcode() == Op_SafePoint) {
1307
dead->as_SafePoint()->disconnect_from_root(this);
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
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) {
1335
} else if (in->is_Store()) {
1336
DUIterator_Fast imax, i = in->fast_outs(imax);
1337
_worklist.push(in->fast_out(i));
1339
if (in->outcnt() == 2) {
1340
_worklist.push(in->fast_out(i));
1343
assert(!(i < imax), "sanity");
1346
BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(this, in);
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()) {
1360
} // if (in != nullptr && in != C->top())
1361
} // for (uint i = 0; i < dead->req(); i++)
1365
} // if (!dead->is_Con())
1366
} // if (progress_state == PROCESS_INPUTS)
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);
1376
// Finished disconnecting all input and output edges.
1378
// Remove dead node from iterative worklist
1379
_worklist.remove(dead);
1380
C->remove_useless_node(dead);
1382
} // while (stack.is_nonempty())
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);
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.
1405
for (uint jmax = use->len(), j = 0; j < jmax; j++) {
1406
if (use->in(j) == old) {
1407
use->set_req(j, nn);
1411
i -= num_edges; // we deleted 1 or more copies of this edge
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);
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) {
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;
1442
temp->destruct(this); // reuse the _idx of this little guy
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
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) {
1473
void PhaseIterGVN::add_users_to_worklist(Node *n) {
1474
add_users_to_worklist0(n, _worklist);
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);
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);
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);
1496
add_users_to_worklist0(p, worklist);
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);
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.
1530
if (use_op == Op_CmpI) {
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).
1541
// CmpINode | CmpINode
1543
// BoolNode | BoolNode
1547
// IfProj | IfProj X
1549
// CastIINode CastIINode
1551
if (in1 != in2) { // if they are equal, the CmpI can fold them away
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
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);
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()) {
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);
1597
// If changed Cast input, notify down for Phi, Sub, and Xor - all do "uncast"
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) {
1608
auto is_boundary = [](Node* n){ return !n->is_ConstraintCast(); };
1609
use->visit_uses(push_the_uses_to_worklist, is_boundary);
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)
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) {
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)) {
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);
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);
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);
1659
add_users_to_worklist0(p, worklist);
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);
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();
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)) {
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();
1701
* Remove the speculative part of all types that we know of
1703
void PhaseIterGVN::remove_speculative_types() {
1704
assert(UseTypeSpeculation, "speculation is off");
1705
for (uint i = 0; i < _types.Size(); i++) {
1706
const Type* t = _types.fast_lookup(i);
1708
_types.map(i, t->remove_speculative());
1711
_table.check_no_speculative_types();
1714
// Check if the type of a divisor of a Div or Mod node includes zero.
1715
bool PhaseIterGVN::no_dependent_zero_check(Node* n) const {
1716
switch (n->Opcode()) {
1719
// Type of divisor includes 0?
1720
if (type(n->in(2)) == Type::TOP) {
1721
// 'n' is dead. Treat as if zero check is still there to avoid any further optimizations.
1724
const TypeInt* type_divisor = type(n->in(2))->is_int();
1725
return (type_divisor->_hi < 0 || type_divisor->_lo > 0);
1729
// Type of divisor includes 0?
1730
if (type(n->in(2)) == Type::TOP) {
1731
// 'n' is dead. Treat as if zero check is still there to avoid any further optimizations.
1734
const TypeLong* type_divisor = type(n->in(2))->is_long();
1735
return (type_divisor->_hi < 0 || type_divisor->_lo > 0);
1741
//=============================================================================
1743
uint PhaseCCP::_total_invokes = 0;
1744
uint PhaseCCP::_total_constants = 0;
1746
//------------------------------PhaseCCP---------------------------------------
1747
// Conditional Constant Propagation, ala Wegman & Zadeck
1748
PhaseCCP::PhaseCCP( PhaseIterGVN *igvn ) : PhaseIterGVN(igvn) {
1749
NOT_PRODUCT( clear_constants(); )
1750
assert( _worklist.size() == 0, "" );
1755
//------------------------------~PhaseCCP--------------------------------------
1756
PhaseCCP::~PhaseCCP() {
1758
_total_constants += count_constants();
1764
void PhaseCCP::verify_type(Node* n, const Type* tnew, const Type* told) {
1765
if (tnew->meet(told) != tnew->remove_speculative()) {
1767
tty->print("told = "); told->dump(); tty->cr();
1768
tty->print("tnew = "); tnew->dump(); tty->cr();
1769
fatal("Not monotonic");
1771
assert(!told->isa_int() || !tnew->isa_int() || told->is_int()->_widen <= tnew->is_int()->_widen, "widen increases");
1772
assert(!told->isa_long() || !tnew->isa_long() || told->is_long()->_widen <= tnew->is_long()->_widen, "widen increases");
1776
// In this analysis, all types are initially set to TOP. We iteratively call Value() on all nodes of the graph until
1777
// we reach a fixed-point (i.e. no types change anymore). We start with a list that only contains the root node. Each time
1778
// a new type is set, we push all uses of that node back to the worklist (in some cases, we also push grandchildren
1779
// or nodes even further down back to the worklist because their type could change as a result of the current type
1781
void PhaseCCP::analyze() {
1782
// Initialize all types to TOP, optimistic analysis
1783
for (uint i = 0; i < C->unique(); i++) {
1784
_types.map(i, Type::TOP);
1787
// CCP worklist is placed on a local arena, so that we can allow ResourceMarks on "Compile::current()->resource_arena()".
1788
// We also do not want to put the worklist on "Compile::current()->comp_arena()", as that one only gets de-allocated after
1789
// Compile is over. The local arena gets de-allocated at the end of its scope.
1790
ResourceArea local_arena(mtCompiler);
1791
Unique_Node_List worklist(&local_arena);
1792
DEBUG_ONLY(Unique_Node_List worklist_verify(&local_arena);)
1794
// Push root onto worklist
1795
worklist.push(C->root());
1797
assert(_root_and_safepoints.size() == 0, "must be empty (unused)");
1798
_root_and_safepoints.push(C->root());
1800
// Pull from worklist; compute new value; push changes out.
1801
// This loop is the meat of CCP.
1802
while (worklist.size() != 0) {
1803
Node* n = fetch_next_node(worklist);
1804
DEBUG_ONLY(worklist_verify.push(n);)
1805
if (n->is_SafePoint()) {
1806
// Make sure safepoints are processed by PhaseCCP::transform even if they are
1807
// not reachable from the bottom. Otherwise, infinite loops would be removed.
1808
_root_and_safepoints.push(n);
1810
const Type* new_type = n->Value(this);
1811
if (new_type != type(n)) {
1812
DEBUG_ONLY(verify_type(n, new_type, type(n));)
1813
dump_type_and_node(n, new_type);
1814
set_type(n, new_type);
1815
push_child_nodes_to_worklist(worklist, n);
1818
DEBUG_ONLY(verify_analyze(worklist_verify);)
1822
// For every node n on verify list, check if type(n) == n->Value()
1823
// We have a list of exceptions, see comments in verify_node_value.
1824
void PhaseCCP::verify_analyze(Unique_Node_List& worklist_verify) {
1825
bool failure = false;
1826
while (worklist_verify.size()) {
1827
Node* n = worklist_verify.pop();
1828
failure |= verify_node_value(n);
1830
// If we get this assert, check why the reported nodes were not processed again in CCP.
1831
// We should either make sure that these nodes are properly added back to the CCP worklist
1832
// in PhaseCCP::push_child_nodes_to_worklist() to update their type or add an exception
1833
// in the verification code above if that is not possible for some reason (like Load nodes).
1834
assert(!failure, "PhaseCCP not at fixpoint: analysis result may be unsound.");
1838
// Fetch next node from worklist to be examined in this iteration.
1839
Node* PhaseCCP::fetch_next_node(Unique_Node_List& worklist) {
1841
return worklist.remove(C->random() % worklist.size());
1843
return worklist.pop();
1848
void PhaseCCP::dump_type_and_node(const Node* n, const Type* t) {
1849
if (TracePhaseCCP) {
1853
} while (tty->position() < 16);
1859
// We need to propagate the type change of 'n' to all its uses. Depending on the kind of node, additional nodes
1860
// (grandchildren or even further down) need to be revisited as their types could also be improved as a result
1861
// of the new type of 'n'. Push these nodes to the worklist.
1862
void PhaseCCP::push_child_nodes_to_worklist(Unique_Node_List& worklist, Node* n) const {
1863
for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1864
Node* use = n->fast_out(i);
1865
push_if_not_bottom_type(worklist, use);
1866
push_more_uses(worklist, n, use);
1870
void PhaseCCP::push_if_not_bottom_type(Unique_Node_List& worklist, Node* n) const {
1871
if (n->bottom_type() != type(n)) {
1876
// For some nodes, we need to propagate the type change to grandchildren or even further down.
1877
// Add them back to the worklist.
1878
void PhaseCCP::push_more_uses(Unique_Node_List& worklist, Node* parent, const Node* use) const {
1879
push_phis(worklist, use);
1880
push_catch(worklist, use);
1881
push_cmpu(worklist, use);
1882
push_counted_loop_phi(worklist, parent, use);
1883
push_loadp(worklist, use);
1884
push_and(worklist, parent, use);
1885
push_cast_ii(worklist, parent, use);
1886
push_opaque_zero_trip_guard(worklist, use);
1890
// We must recheck Phis too if use is a Region.
1891
void PhaseCCP::push_phis(Unique_Node_List& worklist, const Node* use) const {
1892
if (use->is_Region()) {
1893
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1894
push_if_not_bottom_type(worklist, use->fast_out(i));
1899
// If we changed the receiver type to a call, we need to revisit the Catch node following the call. It's looking for a
1900
// non-null receiver to know when to enable the regular fall-through path in addition to the NullPtrException path.
1901
// Same is true if the type of a ValidLengthTest input to an AllocateArrayNode changes.
1902
void PhaseCCP::push_catch(Unique_Node_List& worklist, const Node* use) {
1903
if (use->is_Call()) {
1904
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1905
Node* proj = use->fast_out(i);
1906
if (proj->is_Proj() && proj->as_Proj()->_con == TypeFunc::Control) {
1907
Node* catch_node = proj->find_out_with(Op_Catch);
1908
if (catch_node != nullptr) {
1909
worklist.push(catch_node);
1916
// CmpU nodes can get their type information from two nodes up in the graph (instead of from the nodes immediately
1917
// above). Make sure they are added to the worklist if nodes they depend on are updated since they could be missed
1918
// and get wrong types otherwise.
1919
void PhaseCCP::push_cmpu(Unique_Node_List& worklist, const Node* use) const {
1920
uint use_op = use->Opcode();
1921
if (use_op == Op_AddI || use_op == Op_SubI) {
1922
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1923
Node* cmpu = use->fast_out(i);
1924
const uint cmpu_opcode = cmpu->Opcode();
1925
if (cmpu_opcode == Op_CmpU || cmpu_opcode == Op_CmpU3) {
1926
// Got a CmpU or CmpU3 which might need the new type information from node n.
1927
push_if_not_bottom_type(worklist, cmpu);
1933
// 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'.
1934
// Seem PhiNode::Value().
1935
void PhaseCCP::push_counted_loop_phi(Unique_Node_List& worklist, Node* parent, const Node* use) {
1936
uint use_op = use->Opcode();
1937
if (use_op == Op_CmpI || use_op == Op_CmpL) {
1938
PhiNode* phi = countedloop_phi_from_cmp(use->as_Cmp(), parent);
1939
if (phi != nullptr) {
1945
// Loading the java mirror from a Klass requires two loads and the type of the mirror load depends on the type of 'n'.
1946
// See LoadNode::Value().
1947
void PhaseCCP::push_loadp(Unique_Node_List& worklist, const Node* use) const {
1948
BarrierSetC2* barrier_set = BarrierSet::barrier_set()->barrier_set_c2();
1949
bool has_load_barrier_nodes = barrier_set->has_load_barrier_nodes();
1951
if (use->Opcode() == Op_LoadP && use->bottom_type()->isa_rawptr()) {
1952
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1953
Node* loadp = use->fast_out(i);
1954
const Type* ut = loadp->bottom_type();
1955
if (loadp->Opcode() == Op_LoadP && ut->isa_instptr() && ut != type(loadp)) {
1956
if (has_load_barrier_nodes) {
1957
// Search for load barriers behind the load
1958
push_load_barrier(worklist, barrier_set, loadp);
1960
worklist.push(loadp);
1966
void PhaseCCP::push_load_barrier(Unique_Node_List& worklist, const BarrierSetC2* barrier_set, const Node* use) {
1967
for (DUIterator_Fast imax, i = use->fast_outs(imax); i < imax; i++) {
1968
Node* barrier_node = use->fast_out(i);
1969
if (barrier_set->is_gc_barrier_node(barrier_node)) {
1970
worklist.push(barrier_node);
1975
// AndI/L::Value() optimizes patterns similar to (v << 2) & 3 to zero if they are bitwise disjoint.
1976
// Add the AndI/L nodes back to the worklist to re-apply Value() in case the shift value changed.
1977
// Pattern: parent -> LShift (use) -> (ConstraintCast | ConvI2L)* -> And
1978
void PhaseCCP::push_and(Unique_Node_List& worklist, const Node* parent, const Node* use) const {
1979
uint use_op = use->Opcode();
1980
if ((use_op == Op_LShiftI || use_op == Op_LShiftL)
1981
&& use->in(2) == parent) { // is shift value (right-hand side of LShift)
1982
auto push_and_uses_to_worklist = [&](Node* n){
1983
uint opc = n->Opcode();
1984
if (opc == Op_AndI || opc == Op_AndL) {
1985
push_if_not_bottom_type(worklist, n);
1988
auto is_boundary = [](Node* n) {
1989
return !(n->is_ConstraintCast() || n->Opcode() == Op_ConvI2L);
1991
use->visit_uses(push_and_uses_to_worklist, is_boundary);
1995
// CastII::Value() optimizes CmpI/If patterns if the right input of the CmpI has a constant type. If the CastII input is
1996
// the same node as the left input into the CmpI node, the type of the CastII node can be improved accordingly. Add the
1997
// CastII node back to the worklist to re-apply Value() to either not miss this optimization or to undo it because it
1998
// cannot be applied anymore. We could have optimized the type of the CastII before but now the type of the right input
1999
// of the CmpI (i.e. 'parent') is no longer constant. The type of the CastII must be widened in this case.
2000
void PhaseCCP::push_cast_ii(Unique_Node_List& worklist, const Node* parent, const Node* use) const {
2001
if (use->Opcode() == Op_CmpI && use->in(2) == parent) {
2002
Node* other_cmp_input = use->in(1);
2003
for (DUIterator_Fast imax, i = other_cmp_input->fast_outs(imax); i < imax; i++) {
2004
Node* cast_ii = other_cmp_input->fast_out(i);
2005
if (cast_ii->is_CastII()) {
2006
push_if_not_bottom_type(worklist, cast_ii);
2012
void PhaseCCP::push_opaque_zero_trip_guard(Unique_Node_List& worklist, const Node* use) const {
2013
if (use->Opcode() == Op_OpaqueZeroTripGuard) {
2014
push_if_not_bottom_type(worklist, use->unique_out());
2018
//------------------------------do_transform-----------------------------------
2019
// Top level driver for the recursive transformer
2020
void PhaseCCP::do_transform() {
2021
// Correct leaves of new-space Nodes; they point to old-space.
2022
C->set_root( transform(C->root())->as_Root() );
2023
assert( C->top(), "missing TOP node" );
2024
assert( C->root(), "missing root" );
2027
//------------------------------transform--------------------------------------
2028
// Given a Node in old-space, clone him into new-space.
2029
// Convert any of his old-space children into new-space children.
2030
Node *PhaseCCP::transform( Node *n ) {
2031
assert(n->is_Root(), "traversal must start at root");
2032
assert(_root_and_safepoints.member(n), "root (n) must be in list");
2035
// Map: old node idx -> node after CCP (or nullptr if not yet transformed or useless).
2037
// Pre-allocate to avoid frequent realloc
2038
GrowableArray <Node *> transform_stack(C->live_nodes() >> 1);
2039
// track all visited nodes, so that we can remove the complement
2040
Unique_Node_List useful;
2042
// Initialize the traversal.
2043
// This CCP pass may prove that no exit test for a loop ever succeeds (i.e. the loop is infinite). In that case,
2044
// 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
2045
// 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
2046
// replaced by the top node and the inputs of that node n are not enqueued for further processing. If CCP only works
2047
// through the graph from Root, this causes the loop body to never be processed here even when it's not dead (that
2048
// is reachable from Root following its uses). To prevent that issue, transform() starts walking the graph from Root
2049
// and all safepoints.
2050
for (uint i = 0; i < _root_and_safepoints.size(); ++i) {
2051
Node* nn = _root_and_safepoints.at(i);
2052
Node* new_node = node_map[nn->_idx];
2053
assert(new_node == nullptr, "");
2054
new_node = transform_once(nn); // Check for constant
2055
node_map.map(nn->_idx, new_node); // Flag as having been cloned
2056
transform_stack.push(new_node); // Process children of cloned node
2057
useful.push(new_node);
2060
while (transform_stack.is_nonempty()) {
2061
Node* clone = transform_stack.pop();
2062
uint cnt = clone->req();
2063
for( uint i = 0; i < cnt; i++ ) { // For all inputs do
2064
Node *input = clone->in(i);
2065
if( input != nullptr ) { // Ignore nulls
2066
Node *new_input = node_map[input->_idx]; // Check for cloned input node
2067
if( new_input == nullptr ) {
2068
new_input = transform_once(input); // Check for constant
2069
node_map.map( input->_idx, new_input );// Flag as having been cloned
2070
transform_stack.push(new_input); // Process children of cloned node
2071
useful.push(new_input);
2073
assert( new_input == clone->in(i), "insanity check");
2078
// The above transformation might lead to subgraphs becoming unreachable from the
2079
// bottom while still being reachable from the top. As a result, nodes in that
2080
// subgraph are not transformed and their bottom types are not updated, leading to
2081
// an inconsistency between bottom_type() and type(). In rare cases, LoadNodes in
2082
// such a subgraph, might be re-enqueued for IGVN indefinitely by MemNode::Ideal_common
2083
// because their address type is inconsistent. Therefore, we aggressively remove
2084
// all useless nodes here even before PhaseIdealLoop::build_loop_late gets a chance
2085
// to remove them anyway.
2086
if (C->cached_top_node()) {
2087
useful.push(C->cached_top_node());
2089
C->update_dead_node_list(useful);
2090
remove_useless_nodes(useful.member_set());
2091
_worklist.remove_useless_nodes(useful.member_set());
2092
C->disconnect_useless_nodes(useful, _worklist);
2094
Node* new_root = node_map[n->_idx];
2095
assert(new_root->is_Root(), "transformed root node must be a root node");
2099
//------------------------------transform_once---------------------------------
2100
// For PhaseCCP, transformation is IDENTITY unless Node computed a constant.
2101
Node *PhaseCCP::transform_once( Node *n ) {
2102
const Type *t = type(n);
2103
// Constant? Use constant Node instead
2104
if( t->singleton() ) {
2105
Node *nn = n; // Default is to return the original constant
2106
if( t == Type::TOP ) {
2107
// cache my top node on the Compile instance
2108
if( C->cached_top_node() == nullptr || C->cached_top_node()->in(0) == nullptr ) {
2109
C->set_cached_top_node(ConNode::make(Type::TOP));
2110
set_type(C->top(), Type::TOP);
2114
if( !n->is_Con() ) {
2115
if( t != Type::TOP ) {
2116
nn = makecon(t); // ConNode::make(t);
2117
NOT_PRODUCT( inc_constants(); )
2118
} else if( n->is_Region() ) { // Unreachable region
2119
// Note: nn == C->top()
2120
n->set_req(0, nullptr); // Cut selfreference
2121
bool progress = true;
2122
uint max = n->outcnt();
2126
// Eagerly remove dead phis to avoid phis copies creation.
2127
for (i = n->outs(); n->has_out(i); i++) {
2128
Node* m = n->out(i);
2130
assert(type(m) == Type::TOP, "Unreachable region should not have live phis.");
2131
replace_node(m, nn);
2132
if (max != n->outcnt()) {
2134
i = n->refresh_out_pos(i);
2141
replace_node(n,nn); // Update DefUse edges for new constant
2146
// If x is a TypeNode, capture any more-precise type permanently into Node
2147
if (t != n->bottom_type()) {
2148
hash_delete(n); // changing bottom type may force a rehash
2149
n->raise_bottom_type(t);
2150
_worklist.push(n); // n re-enters the hash table via the worklist
2153
// TEMPORARY fix to ensure that 2nd GVN pass eliminates null checks
2154
switch( n->Opcode() ) {
2155
case Op_CallStaticJava: // Give post-parse call devirtualization a chance
2156
case Op_CallDynamicJava:
2157
case Op_FastLock: // Revisit FastLocks for lock coarsening
2159
case Op_CountedLoopEnd:
2162
case Op_CountedLoop:
2174
//---------------------------------saturate------------------------------------
2175
const Type* PhaseCCP::saturate(const Type* new_type, const Type* old_type,
2176
const Type* limit_type) const {
2177
const Type* wide_type = new_type->widen(old_type, limit_type);
2178
if (wide_type != new_type) { // did we widen?
2179
// If so, we may have widened beyond the limit type. Clip it back down.
2180
new_type = wide_type->filter(limit_type);
2185
//------------------------------print_statistics-------------------------------
2187
void PhaseCCP::print_statistics() {
2188
tty->print_cr("CCP: %d constants found: %d", _total_invokes, _total_constants);
2193
//=============================================================================
2195
uint PhasePeephole::_total_peepholes = 0;
2197
//------------------------------PhasePeephole----------------------------------
2198
// Conditional Constant Propagation, ala Wegman & Zadeck
2199
PhasePeephole::PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg )
2200
: PhaseTransform(Peephole), _regalloc(regalloc), _cfg(cfg) {
2201
NOT_PRODUCT( clear_peepholes(); )
2205
//------------------------------~PhasePeephole---------------------------------
2206
PhasePeephole::~PhasePeephole() {
2207
_total_peepholes += count_peepholes();
2211
//------------------------------transform--------------------------------------
2212
Node *PhasePeephole::transform( Node *n ) {
2213
ShouldNotCallThis();
2217
//------------------------------do_transform-----------------------------------
2218
void PhasePeephole::do_transform() {
2219
bool method_name_not_printed = true;
2221
// Examine each basic block
2222
for (uint block_number = 1; block_number < _cfg.number_of_blocks(); ++block_number) {
2223
Block* block = _cfg.get_block(block_number);
2224
bool block_not_printed = true;
2226
for (bool progress = true; progress;) {
2228
// block->end_idx() not valid after PhaseRegAlloc
2229
uint end_index = block->number_of_nodes();
2230
for( uint instruction_index = end_index - 1; instruction_index > 0; --instruction_index ) {
2231
Node *n = block->get_node(instruction_index);
2232
if( n->is_Mach() ) {
2233
MachNode *m = n->as_Mach();
2234
// check for peephole opportunities
2235
int result = m->peephole(block, instruction_index, &_cfg, _regalloc);
2236
if( result != -1 ) {
2238
if( PrintOptoPeephole ) {
2239
// Print method, first time only
2240
if( C->method() && method_name_not_printed ) {
2241
C->method()->print_short_name(); tty->cr();
2242
method_name_not_printed = false;
2245
if( Verbose && block_not_printed) {
2246
tty->print_cr("in block");
2248
block_not_printed = false;
2250
// Print the peephole number
2251
tty->print_cr("peephole number: %d", result);
2255
// Set progress, start again
2265
//------------------------------print_statistics-------------------------------
2267
void PhasePeephole::print_statistics() {
2268
tty->print_cr("Peephole: peephole rules applied: %d", _total_peepholes);
2273
//=============================================================================
2274
//------------------------------set_req_X--------------------------------------
2275
void Node::set_req_X( uint i, Node *n, PhaseIterGVN *igvn ) {
2276
assert( is_not_dead(n), "can not use dead node");
2278
if (igvn->hash_find(this) == this) {
2279
tty->print_cr("Need to remove from hash before changing edges");
2281
tty->print_cr("Set at i = %d", i);
2283
assert(false, "Need to remove from hash before changing edges");
2291
switch (old->outcnt()) {
2293
// Put into the worklist to kill later. We do not kill it now because the
2294
// recursive kill will delete the current node (this) if dead-loop exists
2296
igvn->_worklist.push( old );
2299
if( old->is_Store() || old->has_special_unique_user() )
2300
igvn->add_users_to_worklist( old );
2303
if( old->is_Store() )
2304
igvn->add_users_to_worklist( old );
2305
if( old->Opcode() == Op_Region )
2306
igvn->_worklist.push(old);
2309
if( old->Opcode() == Op_Region ) {
2310
igvn->_worklist.push(old);
2311
igvn->add_users_to_worklist( old );
2318
BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, old);
2322
void Node::set_req_X(uint i, Node *n, PhaseGVN *gvn) {
2323
PhaseIterGVN* igvn = gvn->is_IterGVN();
2324
if (igvn == nullptr) {
2328
set_req_X(i, n, igvn);
2331
//-------------------------------replace_by-----------------------------------
2332
// Using def-use info, replace one node for another. Follow the def-use info
2333
// to all users of the OLD node. Then make all uses point to the NEW node.
2334
void Node::replace_by(Node *new_node) {
2335
assert(!is_top(), "top node has no DU info");
2336
for (DUIterator_Last imin, i = last_outs(imin); i >= imin; ) {
2337
Node* use = last_out(i);
2338
uint uses_found = 0;
2339
for (uint j = 0; j < use->len(); j++) {
2340
if (use->in(j) == this) {
2342
use->set_req(j, new_node);
2343
else use->set_prec(j, new_node);
2347
i -= uses_found; // we deleted 1 or more copies of this edge
2351
//=============================================================================
2352
//-----------------------------------------------------------------------------
2353
void Type_Array::grow( uint i ) {
2354
assert(_a == Compile::current()->comp_arena(), "Should be allocated in comp_arena");
2357
_types = (const Type**)_a->Amalloc( _max * sizeof(Type*) );
2358
_types[0] = nullptr;
2361
_max = next_power_of_2(i);
2362
_types = (const Type**)_a->Arealloc( _types, old*sizeof(Type*),_max*sizeof(Type*));
2363
memset( &_types[old], 0, (_max-old)*sizeof(Type*) );
2366
//------------------------------dump-------------------------------------------
2368
void Type_Array::dump() const {
2370
for( uint i = 0; i < max; i++ ) {
2371
if( _types[i] != nullptr ) {
2372
tty->print(" %d\t== ", i); _types[i]->dump(); tty->cr();