1 /*
2 * Copyright (c) 1997, 2010, 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
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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).
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15 * You should have received a copy of the GNU General Public License version
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23 */
24
25 #ifndef SHARE_VM_OPTO_PHASEX_HPP
26 #define SHARE_VM_OPTO_PHASEX_HPP
27
28 #include "libadt/dict.hpp"
29 #include "libadt/vectset.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "opto/memnode.hpp"
32 #include "opto/node.hpp"
33 #include "opto/phase.hpp"
34 #include "opto/type.hpp"
35
36 class Compile;
37 class ConINode;
38 class ConLNode;
39 class Node;
40 class Type;
41 class PhaseTransform;
42 class PhaseGVN;
43 class PhaseIterGVN;
44 class PhaseCCP;
45 class PhasePeephole;
46 class PhaseRegAlloc;
47
48
49 //-----------------------------------------------------------------------------
50 // Expandable closed hash-table of nodes, initialized to NULL.
51 // Note that the constructor just zeros things
52 // Storage is reclaimed when the Arena's lifetime is over.
53 class NodeHash : public StackObj {
54 protected:
55 Arena *_a; // Arena to allocate in
56 uint _max; // Size of table (power of 2)
57 uint _inserts; // For grow and debug, count of hash_inserts
58 uint _insert_limit; // 'grow' when _inserts reaches _insert_limit
59 Node **_table; // Hash table of Node pointers
60 Node *_sentinel; // Replaces deleted entries in hash table
61
62 public:
63 NodeHash(uint est_max_size);
64 NodeHash(Arena *arena, uint est_max_size);
65 NodeHash(NodeHash *use_this_state);
66 #ifdef ASSERT
67 ~NodeHash(); // Unlock all nodes upon destruction of table.
68 void operator=(const NodeHash&); // Unlock all nodes upon replacement of table.
69 #endif
70 Node *hash_find(const Node*);// Find an equivalent version in hash table
71 Node *hash_find_insert(Node*);// If not in table insert else return found node
72 void hash_insert(Node*); // Insert into hash table
73 bool hash_delete(const Node*);// Replace with _sentinel in hash table
74 void check_grow() {
75 _inserts++;
76 if( _inserts == _insert_limit ) { grow(); }
77 assert( _inserts <= _insert_limit, "hash table overflow");
78 assert( _inserts < _max, "hash table overflow" );
79 }
80 static uint round_up(uint); // Round up to nearest power of 2
81 void grow(); // Grow _table to next power of 2 and rehash
82 // Return 75% of _max, rounded up.
83 uint insert_limit() const { return _max - (_max>>2); }
84
85 void clear(); // Set all entries to NULL, keep storage.
86 // Size of hash table
87 uint size() const { return _max; }
88 // Return Node* at index in table
89 Node *at(uint table_index) {
90 assert(table_index < _max, "Must be within table");
91 return _table[table_index];
92 }
93
94 void remove_useless_nodes(VectorSet &useful); // replace with sentinel
95
96 Node *sentinel() { return _sentinel; }
97
98 #ifndef PRODUCT
99 Node *find_index(uint idx); // For debugging
100 void dump(); // For debugging, dump statistics
101 #endif
102 uint _grows; // For debugging, count of table grow()s
103 uint _look_probes; // For debugging, count of hash probes
104 uint _lookup_hits; // For debugging, count of hash_finds
105 uint _lookup_misses; // For debugging, count of hash_finds
106 uint _insert_probes; // For debugging, count of hash probes
107 uint _delete_probes; // For debugging, count of hash probes for deletes
108 uint _delete_hits; // For debugging, count of hash probes for deletes
109 uint _delete_misses; // For debugging, count of hash probes for deletes
110 uint _total_inserts; // For debugging, total inserts into hash table
111 uint _total_insert_probes; // For debugging, total probes while inserting
112 };
113
114
115 //-----------------------------------------------------------------------------
116 // Map dense integer indices to Types. Uses classic doubling-array trick.
117 // Abstractly provides an infinite array of Type*'s, initialized to NULL.
118 // Note that the constructor just zeros things, and since I use Arena
119 // allocation I do not need a destructor to reclaim storage.
120 // Despite the general name, this class is customized for use by PhaseTransform.
121 class Type_Array : public StackObj {
122 Arena *_a; // Arena to allocate in
123 uint _max;
124 const Type **_types;
125 void grow( uint i ); // Grow array node to fit
126 const Type *operator[] ( uint i ) const // Lookup, or NULL for not mapped
127 { return (i<_max) ? _types[i] : (Type*)NULL; }
128 friend class PhaseTransform;
129 public:
130 Type_Array(Arena *a) : _a(a), _max(0), _types(0) {}
131 Type_Array(Type_Array *ta) : _a(ta->_a), _max(ta->_max), _types(ta->_types) { }
132 const Type *fast_lookup(uint i) const{assert(i<_max,"oob");return _types[i];}
133 // Extend the mapping: index i maps to Type *n.
134 void map( uint i, const Type *n ) { if( i>=_max ) grow(i); _types[i] = n; }
135 uint Size() const { return _max; }
136 #ifndef PRODUCT
137 void dump() const;
138 #endif
139 };
140
141
142 //------------------------------PhaseRemoveUseless-----------------------------
143 // Remove useless nodes from GVN hash-table, worklist, and graph
144 class PhaseRemoveUseless : public Phase {
145 protected:
146 Unique_Node_List _useful; // Nodes reachable from root
147 // list is allocated from current resource area
148 public:
149 PhaseRemoveUseless( PhaseGVN *gvn, Unique_Node_List *worklist );
150
151 Unique_Node_List *get_useful() { return &_useful; }
152 };
153
154
155 //------------------------------PhaseTransform---------------------------------
156 // Phases that analyze, then transform. Constructing the Phase object does any
157 // global or slow analysis. The results are cached later for a fast
158 // transformation pass. When the Phase object is deleted the cached analysis
159 // results are deleted.
160 class PhaseTransform : public Phase {
161 protected:
162 Arena* _arena;
163 Node_Array _nodes; // Map old node indices to new nodes.
164 Type_Array _types; // Map old node indices to Types.
165
166 // ConNode caches:
167 enum { _icon_min = -1 * HeapWordSize,
168 _icon_max = 16 * HeapWordSize,
169 _lcon_min = _icon_min,
170 _lcon_max = _icon_max,
171 _zcon_max = (uint)T_CONFLICT
172 };
173 ConINode* _icons[_icon_max - _icon_min + 1]; // cached jint constant nodes
174 ConLNode* _lcons[_lcon_max - _lcon_min + 1]; // cached jlong constant nodes
175 ConNode* _zcons[_zcon_max + 1]; // cached is_zero_type nodes
176 void init_con_caches();
177
178 // Support both int and long caches because either might be an intptr_t,
179 // so they show up frequently in address computations.
180
181 public:
182 PhaseTransform( PhaseNumber pnum );
183 PhaseTransform( Arena *arena, PhaseNumber pnum );
184 PhaseTransform( PhaseTransform *phase, PhaseNumber pnum );
185
186 Arena* arena() { return _arena; }
187 Type_Array& types() { return _types; }
188 // _nodes is used in varying ways by subclasses, which define local accessors
189
190 public:
191 // Get a previously recorded type for the node n.
192 // This type must already have been recorded.
193 // If you want the type of a very new (untransformed) node,
194 // you must use type_or_null, and test the result for NULL.
195 const Type* type(const Node* n) const {
196 const Type* t = _types.fast_lookup(n->_idx);
197 assert(t != NULL, "must set before get");
198 return t;
199 }
200 // Get a previously recorded type for the node n,
201 // or else return NULL if there is none.
202 const Type* type_or_null(const Node* n) const {
203 return _types.fast_lookup(n->_idx);
204 }
205 // Record a type for a node.
206 void set_type(const Node* n, const Type *t) {
207 assert(t != NULL, "type must not be null");
208 _types.map(n->_idx, t);
209 }
210 // Record an initial type for a node, the node's bottom type.
211 void set_type_bottom(const Node* n) {
212 // Use this for initialization when bottom_type() (or better) is not handy.
213 // Usually the initialization shoudl be to n->Value(this) instead,
214 // or a hand-optimized value like Type::MEMORY or Type::CONTROL.
215 assert(_types[n->_idx] == NULL, "must set the initial type just once");
216 _types.map(n->_idx, n->bottom_type());
217 }
218 // Make sure the types array is big enough to record a size for the node n.
219 // (In product builds, we never want to do range checks on the types array!)
220 void ensure_type_or_null(const Node* n) {
221 if (n->_idx >= _types.Size())
222 _types.map(n->_idx, NULL); // Grow the types array as needed.
223 }
224
225 // Utility functions:
226 const TypeInt* find_int_type( Node* n);
227 const TypeLong* find_long_type(Node* n);
228 jint find_int_con( Node* n, jint value_if_unknown) {
229 const TypeInt* t = find_int_type(n);
230 return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
231 }
232 jlong find_long_con(Node* n, jlong value_if_unknown) {
233 const TypeLong* t = find_long_type(n);
234 return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
235 }
236
237 // Make an idealized constant, i.e., one of ConINode, ConPNode, ConFNode, etc.
238 // Same as transform(ConNode::make(t)).
239 ConNode* makecon(const Type* t);
240 virtual ConNode* uncached_makecon(const Type* t) // override in PhaseValues
241 { ShouldNotCallThis(); return NULL; }
242
243 // Fast int or long constant. Same as TypeInt::make(i) or TypeLong::make(l).
244 ConINode* intcon(jint i);
245 ConLNode* longcon(jlong l);
246
247 // Fast zero or null constant. Same as makecon(Type::get_zero_type(bt)).
248 ConNode* zerocon(BasicType bt);
249
250 // Return a node which computes the same function as this node, but
251 // in a faster or cheaper fashion.
252 virtual Node *transform( Node *n ) = 0;
253
254 // Return whether two Nodes are equivalent.
255 // Must not be recursive, since the recursive version is built from this.
256 // For pessimistic optimizations this is simply pointer equivalence.
257 bool eqv(const Node* n1, const Node* n2) const { return n1 == n2; }
258
259 // Return whether two Nodes are equivalent, after stripping casting.
260 bool eqv_uncast(const Node* n1, const Node* n2) const {
261 return eqv(n1->uncast(), n2->uncast());
262 }
263
264 // For pessimistic passes, the return type must monotonically narrow.
265 // For optimistic passes, the return type must monotonically widen.
266 // It is possible to get into a "death march" in either type of pass,
267 // where the types are continually moving but it will take 2**31 or
268 // more steps to converge. This doesn't happen on most normal loops.
269 //
270 // Here is an example of a deadly loop for an optimistic pass, along
271 // with a partial trace of inferred types:
272 // x = phi(0,x'); L: x' = x+1; if (x' >= 0) goto L;
273 // 0 1 join([0..max], 1)
274 // [0..1] [1..2] join([0..max], [1..2])
275 // [0..2] [1..3] join([0..max], [1..3])
276 // ... ... ...
277 // [0..max] [min]u[1..max] join([0..max], [min..max])
278 // [0..max] ==> fixpoint
279 // We would have proven, the hard way, that the iteration space is all
280 // non-negative ints, with the loop terminating due to 32-bit overflow.
281 //
282 // Here is the corresponding example for a pessimistic pass:
283 // x = phi(0,x'); L: x' = x-1; if (x' >= 0) goto L;
284 // int int join([0..max], int)
285 // [0..max] [-1..max-1] join([0..max], [-1..max-1])
286 // [0..max-1] [-1..max-2] join([0..max], [-1..max-2])
287 // ... ... ...
288 // [0..1] [-1..0] join([0..max], [-1..0])
289 // 0 -1 join([0..max], -1)
290 // 0 == fixpoint
291 // We would have proven, the hard way, that the iteration space is {0}.
292 // (Usually, other optimizations will make the "if (x >= 0)" fold up
293 // before we get into trouble. But not always.)
294 //
295 // It's a pleasant thing to observe that the pessimistic pass
296 // will make short work of the optimistic pass's deadly loop,
297 // and vice versa. That is a good example of the complementary
298 // purposes of the CCP (optimistic) vs. GVN (pessimistic) phases.
299 //
300 // In any case, only widen or narrow a few times before going to the
301 // correct flavor of top or bottom.
302 //
303 // This call only needs to be made once as the data flows around any
304 // given cycle. We do it at Phis, and nowhere else.
305 // The types presented are the new type of a phi (computed by PhiNode::Value)
306 // and the previously computed type, last time the phi was visited.
307 //
308 // The third argument is upper limit for the saturated value,
309 // if the phase wishes to widen the new_type.
310 // If the phase is narrowing, the old type provides a lower limit.
311 // Caller guarantees that old_type and new_type are no higher than limit_type.
312 virtual const Type* saturate(const Type* new_type, const Type* old_type,
313 const Type* limit_type) const
314 { ShouldNotCallThis(); return NULL; }
315
316 #ifndef PRODUCT
317 void dump_old2new_map() const;
318 void dump_new( uint new_lidx ) const;
319 void dump_types() const;
320 void dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl = true);
321 void dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited);
322
323 uint _count_progress; // For profiling, count transforms that make progress
324 void set_progress() { ++_count_progress; assert( allow_progress(),"No progress allowed during verification"); }
325 void clear_progress() { _count_progress = 0; }
326 uint made_progress() const { return _count_progress; }
327
328 uint _count_transforms; // For profiling, count transforms performed
329 void set_transforms() { ++_count_transforms; }
330 void clear_transforms() { _count_transforms = 0; }
331 uint made_transforms() const{ return _count_transforms; }
332
333 bool _allow_progress; // progress not allowed during verification pass
334 void set_allow_progress(bool allow) { _allow_progress = allow; }
335 bool allow_progress() { return _allow_progress; }
336 #endif
337 };
338
339 //------------------------------PhaseValues------------------------------------
340 // Phase infrastructure to support values
341 class PhaseValues : public PhaseTransform {
342 protected:
343 NodeHash _table; // Hash table for value-numbering
344
345 public:
346 PhaseValues( Arena *arena, uint est_max_size );
347 PhaseValues( PhaseValues *pt );
348 PhaseValues( PhaseValues *ptv, const char *dummy );
349 NOT_PRODUCT( ~PhaseValues(); )
350 virtual PhaseIterGVN *is_IterGVN() { return 0; }
351
352 // Some Ideal and other transforms delete --> modify --> insert values
353 bool hash_delete(Node *n) { return _table.hash_delete(n); }
354 void hash_insert(Node *n) { _table.hash_insert(n); }
355 Node *hash_find_insert(Node *n){ return _table.hash_find_insert(n); }
356 Node *hash_find(const Node *n) { return _table.hash_find(n); }
357
358 // Used after parsing to eliminate values that are no longer in program
359 void remove_useless_nodes(VectorSet &useful) {
360 _table.remove_useless_nodes(useful);
361 // this may invalidate cached cons so reset the cache
362 init_con_caches();
363 }
364
365 virtual ConNode* uncached_makecon(const Type* t); // override from PhaseTransform
366
367 virtual const Type* saturate(const Type* new_type, const Type* old_type,
368 const Type* limit_type) const
369 { return new_type; }
370
371 #ifndef PRODUCT
372 uint _count_new_values; // For profiling, count new values produced
373 void inc_new_values() { ++_count_new_values; }
374 void clear_new_values() { _count_new_values = 0; }
375 uint made_new_values() const { return _count_new_values; }
376 #endif
377 };
378
379
380 //------------------------------PhaseGVN---------------------------------------
381 // Phase for performing local, pessimistic GVN-style optimizations.
382 class PhaseGVN : public PhaseValues {
383 public:
384 PhaseGVN( Arena *arena, uint est_max_size ) : PhaseValues( arena, est_max_size ) {}
385 PhaseGVN( PhaseGVN *gvn ) : PhaseValues( gvn ) {}
386 PhaseGVN( PhaseGVN *gvn, const char *dummy ) : PhaseValues( gvn, dummy ) {}
387
388 // Return a node which computes the same function as this node, but
389 // in a faster or cheaper fashion.
390 Node *transform( Node *n );
391 Node *transform_no_reclaim( Node *n );
392
393 // Check for a simple dead loop when a data node references itself.
394 DEBUG_ONLY(void dead_loop_check(Node *n);)
395 };
396
397 //------------------------------PhaseIterGVN-----------------------------------
398 // Phase for iteratively performing local, pessimistic GVN-style optimizations.
399 // and ideal transformations on the graph.
400 class PhaseIterGVN : public PhaseGVN {
401 private:
402 bool _delay_transform; // When true simply register the node when calling transform
403 // instead of actually optimizing it
404
405 // Idealize old Node 'n' with respect to its inputs and its value
406 virtual Node *transform_old( Node *a_node );
407
408 // Subsume users of node 'old' into node 'nn'
409 void subsume_node( Node *old, Node *nn );
410
411 protected:
412
413 // Idealize new Node 'n' with respect to its inputs and its value
414 virtual Node *transform( Node *a_node );
415
416 // Warm up hash table, type table and initial worklist
417 void init_worklist( Node *a_root );
418
419 virtual const Type* saturate(const Type* new_type, const Type* old_type,
420 const Type* limit_type) const;
421 // Usually returns new_type. Returns old_type if new_type is only a slight
422 // improvement, such that it would take many (>>10) steps to reach 2**32.
423
424 public:
425 PhaseIterGVN( PhaseIterGVN *igvn ); // Used by CCP constructor
426 PhaseIterGVN( PhaseGVN *gvn ); // Used after Parser
427 PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ); // Used after +VerifyOpto
428
429 virtual PhaseIterGVN *is_IterGVN() { return this; }
430
431 Unique_Node_List _worklist; // Iterative worklist
432
433 // Given def-use info and an initial worklist, apply Node::Ideal,
434 // Node::Value, Node::Identity, hash-based value numbering, Node::Ideal_DU
435 // and dominator info to a fixed point.
436 void optimize();
437
438 // Register a new node with the iter GVN pass without transforming it.
439 // Used when we need to restructure a Region/Phi area and all the Regions
440 // and Phis need to complete this one big transform before any other
441 // transforms can be triggered on the region.
442 // Optional 'orig' is an earlier version of this node.
443 // It is significant only for debugging and profiling.
444 Node* register_new_node_with_optimizer(Node* n, Node* orig = NULL);
445
446 // Kill a globally dead Node. It is allowed to have uses which are
447 // assumed dead and left 'in limbo'.
448 void remove_globally_dead_node( Node *dead );
449
450 // Kill all inputs to a dead node, recursively making more dead nodes.
451 // The Node must be dead locally, i.e., have no uses.
452 void remove_dead_node( Node *dead ) {
453 assert(dead->outcnt() == 0 && !dead->is_top(), "node must be dead");
454 remove_globally_dead_node(dead);
455 }
456
457 // Add users of 'n' to worklist
458 void add_users_to_worklist0( Node *n );
459 void add_users_to_worklist ( Node *n );
460
461 // Replace old node with new one.
462 void replace_node( Node *old, Node *nn ) {
463 add_users_to_worklist(old);
464 hash_delete(old); // Yank from hash before hacking edges
465 subsume_node(old, nn);
466 }
467
468 bool delay_transform() const { return _delay_transform; }
469
470 void set_delay_transform(bool delay) {
471 _delay_transform = delay;
472 }
473
474 // Clone loop predicates. Defined in loopTransform.cpp.
475 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
476 Node* move_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
477 // Create a new if below new_entry for the predicate to be cloned
478 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
479 Deoptimization::DeoptReason reason);
480
481 #ifndef PRODUCT
482 protected:
483 // Sub-quadratic implementation of VerifyIterativeGVN.
484 unsigned long _verify_counter;
485 unsigned long _verify_full_passes;
486 enum { _verify_window_size = 30 };
487 Node* _verify_window[_verify_window_size];
488 void verify_step(Node* n);
489 #endif
490 };
491
492 //------------------------------PhaseCCP---------------------------------------
493 // Phase for performing global Conditional Constant Propagation.
494 // Should be replaced with combined CCP & GVN someday.
495 class PhaseCCP : public PhaseIterGVN {
496 // Non-recursive. Use analysis to transform single Node.
497 virtual Node *transform_once( Node *n );
498
499 public:
500 PhaseCCP( PhaseIterGVN *igvn ); // Compute conditional constants
501 NOT_PRODUCT( ~PhaseCCP(); )
502
503 // Worklist algorithm identifies constants
504 void analyze();
505 // Recursive traversal of program. Used analysis to modify program.
506 virtual Node *transform( Node *n );
507 // Do any transformation after analysis
508 void do_transform();
509
510 virtual const Type* saturate(const Type* new_type, const Type* old_type,
511 const Type* limit_type) const;
512 // Returns new_type->widen(old_type), which increments the widen bits until
513 // giving up with TypeInt::INT or TypeLong::LONG.
514 // Result is clipped to limit_type if necessary.
515
516 #ifndef PRODUCT
517 static uint _total_invokes; // For profiling, count invocations
518 void inc_invokes() { ++PhaseCCP::_total_invokes; }
519
520 static uint _total_constants; // For profiling, count constants found
521 uint _count_constants;
522 void clear_constants() { _count_constants = 0; }
523 void inc_constants() { ++_count_constants; }
524 uint count_constants() const { return _count_constants; }
525
526 static void print_statistics();
527 #endif
528 };
529
530
531 //------------------------------PhasePeephole----------------------------------
532 // Phase for performing peephole optimizations on register allocated basic blocks.
533 class PhasePeephole : public PhaseTransform {
534 PhaseRegAlloc *_regalloc;
535 PhaseCFG &_cfg;
536 // Recursive traversal of program. Pure function is unused in this phase
537 virtual Node *transform( Node *n );
538
539 public:
540 PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg );
541 NOT_PRODUCT( ~PhasePeephole(); )
542
543 // Do any transformation after analysis
544 void do_transform();
545
546 #ifndef PRODUCT
547 static uint _total_peepholes; // For profiling, count peephole rules applied
548 uint _count_peepholes;
549 void clear_peepholes() { _count_peepholes = 0; }
550 void inc_peepholes() { ++_count_peepholes; }
551 uint count_peepholes() const { return _count_peepholes; }
552
553 static void print_statistics();
554 #endif
555 };
556
557 #endif // SHARE_VM_OPTO_PHASEX_HPP