1 /*
2 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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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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 assert(n != NULL, "must not be null");
197 const Type* t = _types.fast_lookup(n->_idx);
198 assert(t != NULL, "must set before get");
199 return t;
200 }
201 // Get a previously recorded type for the node n,
202 // or else return NULL if there is none.
203 const Type* type_or_null(const Node* n) const {
204 return _types.fast_lookup(n->_idx);
205 }
206 // Record a type for a node.
207 void set_type(const Node* n, const Type *t) {
208 assert(t != NULL, "type must not be null");
209 _types.map(n->_idx, t);
210 }
211 // Record an initial type for a node, the node's bottom type.
212 void set_type_bottom(const Node* n) {
213 // Use this for initialization when bottom_type() (or better) is not handy.
214 // Usually the initialization shoudl be to n->Value(this) instead,
215 // or a hand-optimized value like Type::MEMORY or Type::CONTROL.
216 assert(_types[n->_idx] == NULL, "must set the initial type just once");
217 _types.map(n->_idx, n->bottom_type());
218 }
219 // Make sure the types array is big enough to record a size for the node n.
220 // (In product builds, we never want to do range checks on the types array!)
221 void ensure_type_or_null(const Node* n) {
222 if (n->_idx >= _types.Size())
223 _types.map(n->_idx, NULL); // Grow the types array as needed.
224 }
225
226 // Utility functions:
227 const TypeInt* find_int_type( Node* n);
228 const TypeLong* find_long_type(Node* n);
229 jint find_int_con( Node* n, jint value_if_unknown) {
230 const TypeInt* t = find_int_type(n);
231 return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
232 }
233 jlong find_long_con(Node* n, jlong value_if_unknown) {
234 const TypeLong* t = find_long_type(n);
235 return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
236 }
237
238 // Make an idealized constant, i.e., one of ConINode, ConPNode, ConFNode, etc.
239 // Same as transform(ConNode::make(t)).
240 ConNode* makecon(const Type* t);
241 virtual ConNode* uncached_makecon(const Type* t) // override in PhaseValues
242 { ShouldNotCallThis(); return NULL; }
243
244 // Fast int or long constant. Same as TypeInt::make(i) or TypeLong::make(l).
245 ConINode* intcon(jint i);
246 ConLNode* longcon(jlong l);
247
248 // Fast zero or null constant. Same as makecon(Type::get_zero_type(bt)).
249 ConNode* zerocon(BasicType bt);
250
251 // Return a node which computes the same function as this node, but
252 // in a faster or cheaper fashion.
253 virtual Node *transform( Node *n ) = 0;
254
255 // Return whether two Nodes are equivalent.
256 // Must not be recursive, since the recursive version is built from this.
257 // For pessimistic optimizations this is simply pointer equivalence.
258 bool eqv(const Node* n1, const Node* n2) const { return n1 == n2; }
259
260 // For pessimistic passes, the return type must monotonically narrow.
261 // For optimistic passes, the return type must monotonically widen.
262 // It is possible to get into a "death march" in either type of pass,
263 // where the types are continually moving but it will take 2**31 or
264 // more steps to converge. This doesn't happen on most normal loops.
265 //
266 // Here is an example of a deadly loop for an optimistic pass, along
267 // with a partial trace of inferred types:
268 // x = phi(0,x'); L: x' = x+1; if (x' >= 0) goto L;
269 // 0 1 join([0..max], 1)
270 // [0..1] [1..2] join([0..max], [1..2])
271 // [0..2] [1..3] join([0..max], [1..3])
272 // ... ... ...
273 // [0..max] [min]u[1..max] join([0..max], [min..max])
274 // [0..max] ==> fixpoint
275 // We would have proven, the hard way, that the iteration space is all
276 // non-negative ints, with the loop terminating due to 32-bit overflow.
277 //
278 // Here is the corresponding example for a pessimistic pass:
279 // x = phi(0,x'); L: x' = x-1; if (x' >= 0) goto L;
280 // int int join([0..max], int)
281 // [0..max] [-1..max-1] join([0..max], [-1..max-1])
282 // [0..max-1] [-1..max-2] join([0..max], [-1..max-2])
283 // ... ... ...
284 // [0..1] [-1..0] join([0..max], [-1..0])
285 // 0 -1 join([0..max], -1)
286 // 0 == fixpoint
287 // We would have proven, the hard way, that the iteration space is {0}.
288 // (Usually, other optimizations will make the "if (x >= 0)" fold up
289 // before we get into trouble. But not always.)
290 //
291 // It's a pleasant thing to observe that the pessimistic pass
292 // will make short work of the optimistic pass's deadly loop,
293 // and vice versa. That is a good example of the complementary
294 // purposes of the CCP (optimistic) vs. GVN (pessimistic) phases.
295 //
296 // In any case, only widen or narrow a few times before going to the
297 // correct flavor of top or bottom.
298 //
299 // This call only needs to be made once as the data flows around any
300 // given cycle. We do it at Phis, and nowhere else.
301 // The types presented are the new type of a phi (computed by PhiNode::Value)
302 // and the previously computed type, last time the phi was visited.
303 //
304 // The third argument is upper limit for the saturated value,
305 // if the phase wishes to widen the new_type.
306 // If the phase is narrowing, the old type provides a lower limit.
307 // Caller guarantees that old_type and new_type are no higher than limit_type.
308 virtual const Type* saturate(const Type* new_type, const Type* old_type,
309 const Type* limit_type) const
310 { ShouldNotCallThis(); return NULL; }
311
312 #ifndef PRODUCT
313 void dump_old2new_map() const;
314 void dump_new( uint new_lidx ) const;
315 void dump_types() const;
316 void dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl = true);
317 void dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited);
318
319 uint _count_progress; // For profiling, count transforms that make progress
320 void set_progress() { ++_count_progress; assert( allow_progress(),"No progress allowed during verification"); }
321 void clear_progress() { _count_progress = 0; }
322 uint made_progress() const { return _count_progress; }
323
324 uint _count_transforms; // For profiling, count transforms performed
325 void set_transforms() { ++_count_transforms; }
326 void clear_transforms() { _count_transforms = 0; }
327 uint made_transforms() const{ return _count_transforms; }
328
329 bool _allow_progress; // progress not allowed during verification pass
330 void set_allow_progress(bool allow) { _allow_progress = allow; }
331 bool allow_progress() { return _allow_progress; }
332 #endif
333 };
334
335 //------------------------------PhaseValues------------------------------------
336 // Phase infrastructure to support values
337 class PhaseValues : public PhaseTransform {
338 protected:
339 NodeHash _table; // Hash table for value-numbering
340
341 public:
342 PhaseValues( Arena *arena, uint est_max_size );
343 PhaseValues( PhaseValues *pt );
344 PhaseValues( PhaseValues *ptv, const char *dummy );
345 NOT_PRODUCT( ~PhaseValues(); )
346 virtual PhaseIterGVN *is_IterGVN() { return 0; }
347
348 // Some Ideal and other transforms delete --> modify --> insert values
349 bool hash_delete(Node *n) { return _table.hash_delete(n); }
350 void hash_insert(Node *n) { _table.hash_insert(n); }
351 Node *hash_find_insert(Node *n){ return _table.hash_find_insert(n); }
352 Node *hash_find(const Node *n) { return _table.hash_find(n); }
353
354 // Used after parsing to eliminate values that are no longer in program
355 void remove_useless_nodes(VectorSet &useful) {
356 _table.remove_useless_nodes(useful);
357 // this may invalidate cached cons so reset the cache
358 init_con_caches();
359 }
360
361 virtual ConNode* uncached_makecon(const Type* t); // override from PhaseTransform
362
363 virtual const Type* saturate(const Type* new_type, const Type* old_type,
364 const Type* limit_type) const
365 { return new_type; }
366
367 #ifndef PRODUCT
368 uint _count_new_values; // For profiling, count new values produced
369 void inc_new_values() { ++_count_new_values; }
370 void clear_new_values() { _count_new_values = 0; }
371 uint made_new_values() const { return _count_new_values; }
372 #endif
373 };
374
375
376 //------------------------------PhaseGVN---------------------------------------
377 // Phase for performing local, pessimistic GVN-style optimizations.
378 class PhaseGVN : public PhaseValues {
379 public:
380 PhaseGVN( Arena *arena, uint est_max_size ) : PhaseValues( arena, est_max_size ) {}
381 PhaseGVN( PhaseGVN *gvn ) : PhaseValues( gvn ) {}
382 PhaseGVN( PhaseGVN *gvn, const char *dummy ) : PhaseValues( gvn, dummy ) {}
383
384 // Return a node which computes the same function as this node, but
385 // in a faster or cheaper fashion.
386 Node *transform( Node *n );
387 Node *transform_no_reclaim( Node *n );
388
389 // Check for a simple dead loop when a data node references itself.
390 DEBUG_ONLY(void dead_loop_check(Node *n);)
391 };
392
393 //------------------------------PhaseIterGVN-----------------------------------
394 // Phase for iteratively performing local, pessimistic GVN-style optimizations.
395 // and ideal transformations on the graph.
396 class PhaseIterGVN : public PhaseGVN {
397 private:
398 bool _delay_transform; // When true simply register the node when calling transform
399 // instead of actually optimizing it
400
401 // Idealize old Node 'n' with respect to its inputs and its value
402 virtual Node *transform_old( Node *a_node );
403
404 // Subsume users of node 'old' into node 'nn'
405 void subsume_node( Node *old, Node *nn );
406
407 Node_Stack _stack; // Stack used to avoid recursion
408
409 protected:
410
411 // Idealize new Node 'n' with respect to its inputs and its value
412 virtual Node *transform( Node *a_node );
413
414 // Warm up hash table, type table and initial worklist
415 void init_worklist( Node *a_root );
416
417 virtual const Type* saturate(const Type* new_type, const Type* old_type,
418 const Type* limit_type) const;
419 // Usually returns new_type. Returns old_type if new_type is only a slight
420 // improvement, such that it would take many (>>10) steps to reach 2**32.
421
422 public:
423 PhaseIterGVN( PhaseIterGVN *igvn ); // Used by CCP constructor
424 PhaseIterGVN( PhaseGVN *gvn ); // Used after Parser
425 PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ); // Used after +VerifyOpto
426
427 virtual PhaseIterGVN *is_IterGVN() { return this; }
428
429 Unique_Node_List _worklist; // Iterative worklist
430
431 // Given def-use info and an initial worklist, apply Node::Ideal,
432 // Node::Value, Node::Identity, hash-based value numbering, Node::Ideal_DU
433 // and dominator info to a fixed point.
434 void optimize();
435
436 // Register a new node with the iter GVN pass without transforming it.
437 // Used when we need to restructure a Region/Phi area and all the Regions
438 // and Phis need to complete this one big transform before any other
439 // transforms can be triggered on the region.
440 // Optional 'orig' is an earlier version of this node.
441 // It is significant only for debugging and profiling.
442 Node* register_new_node_with_optimizer(Node* n, Node* orig = NULL);
443
444 // Kill a globally dead Node. All uses are also globally dead and are
445 // aggressively trimmed.
446 void remove_globally_dead_node( Node *dead );
447
448 // Kill all inputs to a dead node, recursively making more dead nodes.
449 // The Node must be dead locally, i.e., have no uses.
450 void remove_dead_node( Node *dead ) {
451 assert(dead->outcnt() == 0 && !dead->is_top(), "node must be dead");
452 remove_globally_dead_node(dead);
453 }
454
455 // Add users of 'n' to worklist
456 void add_users_to_worklist0( Node *n );
457 void add_users_to_worklist ( Node *n );
458
459 // Replace old node with new one.
460 void replace_node( Node *old, Node *nn ) {
461 add_users_to_worklist(old);
462 hash_delete(old); // Yank from hash before hacking edges
463 subsume_node(old, nn);
464 }
465
466 // Delayed node rehash: remove a node from the hash table and rehash it during
467 // next optimizing pass
468 void rehash_node_delayed(Node* n) {
469 hash_delete(n);
470 _worklist.push(n);
471 }
472
473 // Replace ith edge of "n" with "in"
474 void replace_input_of(Node* n, int i, Node* in) {
475 rehash_node_delayed(n);
476 n->set_req(i, in);
477 }
478
479 // Delete ith edge of "n"
480 void delete_input_of(Node* n, int i) {
481 rehash_node_delayed(n);
482 n->del_req(i);
483 }
484
485 bool delay_transform() const { return _delay_transform; }
486
487 void set_delay_transform(bool delay) {
488 _delay_transform = delay;
489 }
490
491 // Clone loop predicates. Defined in loopTransform.cpp.
492 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
493 // Create a new if below new_entry for the predicate to be cloned
494 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
495 Deoptimization::DeoptReason reason);
496
497 #ifndef PRODUCT
498 protected:
499 // Sub-quadratic implementation of VerifyIterativeGVN.
500 julong _verify_counter;
501 julong _verify_full_passes;
502 enum { _verify_window_size = 30 };
503 Node* _verify_window[_verify_window_size];
504 void verify_step(Node* n);
505 #endif
506 };
507
508 //------------------------------PhaseCCP---------------------------------------
509 // Phase for performing global Conditional Constant Propagation.
510 // Should be replaced with combined CCP & GVN someday.
511 class PhaseCCP : public PhaseIterGVN {
512 // Non-recursive. Use analysis to transform single Node.
513 virtual Node *transform_once( Node *n );
514
515 public:
516 PhaseCCP( PhaseIterGVN *igvn ); // Compute conditional constants
517 NOT_PRODUCT( ~PhaseCCP(); )
518
519 // Worklist algorithm identifies constants
520 void analyze();
521 // Recursive traversal of program. Used analysis to modify program.
522 virtual Node *transform( Node *n );
523 // Do any transformation after analysis
524 void do_transform();
525
526 virtual const Type* saturate(const Type* new_type, const Type* old_type,
527 const Type* limit_type) const;
528 // Returns new_type->widen(old_type), which increments the widen bits until
529 // giving up with TypeInt::INT or TypeLong::LONG.
530 // Result is clipped to limit_type if necessary.
531
532 #ifndef PRODUCT
533 static uint _total_invokes; // For profiling, count invocations
534 void inc_invokes() { ++PhaseCCP::_total_invokes; }
535
536 static uint _total_constants; // For profiling, count constants found
537 uint _count_constants;
538 void clear_constants() { _count_constants = 0; }
539 void inc_constants() { ++_count_constants; }
540 uint count_constants() const { return _count_constants; }
541
542 static void print_statistics();
543 #endif
544 };
545
546
547 //------------------------------PhasePeephole----------------------------------
548 // Phase for performing peephole optimizations on register allocated basic blocks.
549 class PhasePeephole : public PhaseTransform {
550 PhaseRegAlloc *_regalloc;
551 PhaseCFG &_cfg;
552 // Recursive traversal of program. Pure function is unused in this phase
553 virtual Node *transform( Node *n );
554
555 public:
556 PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg );
557 NOT_PRODUCT( ~PhasePeephole(); )
558
559 // Do any transformation after analysis
560 void do_transform();
561
562 #ifndef PRODUCT
563 static uint _total_peepholes; // For profiling, count peephole rules applied
564 uint _count_peepholes;
565 void clear_peepholes() { _count_peepholes = 0; }
566 void inc_peepholes() { ++_count_peepholes; }
567 uint count_peepholes() const { return _count_peepholes; }
568
569 static void print_statistics();
570 #endif
571 };
572
573 #endif // SHARE_VM_OPTO_PHASEX_HPP