1 /*
  2  * Copyright (c) 1997, 2019, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
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 24 
 25 #ifndef SHARE_OPTO_PHASEX_HPP
 26 #define SHARE_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   void   replace_with(NodeHash* nh);
 96   void   check_no_speculative_types(); // Check no speculative part for type nodes in table
 97 
 98   Node  *sentinel() { return _sentinel; }
 99 
100 #ifndef PRODUCT
101   Node  *find_index(uint idx);  // For debugging
102   void   dump();                // For debugging, dump statistics
103   uint   _grows;                // For debugging, count of table grow()s
104   uint   _look_probes;          // For debugging, count of hash probes
105   uint   _lookup_hits;          // For debugging, count of hash_finds
106   uint   _lookup_misses;        // For debugging, count of hash_finds
107   uint   _insert_probes;        // For debugging, count of hash probes
108   uint   _delete_probes;        // For debugging, count of hash probes for deletes
109   uint   _delete_hits;          // For debugging, count of hash probes for deletes
110   uint   _delete_misses;        // For debugging, count of hash probes for deletes
111   uint   _total_inserts;        // For debugging, total inserts into hash table
112   uint   _total_insert_probes;  // For debugging, total probes while inserting
113 #endif
114 };
115 
116 
117 //-----------------------------------------------------------------------------
118 // Map dense integer indices to Types.  Uses classic doubling-array trick.
119 // Abstractly provides an infinite array of Type*'s, initialized to NULL.
120 // Note that the constructor just zeros things, and since I use Arena
121 // allocation I do not need a destructor to reclaim storage.
122 // Despite the general name, this class is customized for use by PhaseTransform.
123 class Type_Array : public StackObj {
124   Arena *_a;                    // Arena to allocate in
125   uint   _max;
126   const Type **_types;
127   void grow( uint i );          // Grow array node to fit
128   const Type *operator[] ( uint i ) const // Lookup, or NULL for not mapped
129   { return (i<_max) ? _types[i] : (Type*)NULL; }
130   friend class PhaseTransform;
131 public:
132   Type_Array(Arena *a) : _a(a), _max(0), _types(0) {}
133   Type_Array(Type_Array *ta) : _a(ta->_a), _max(ta->_max), _types(ta->_types) { }
134   const Type *fast_lookup(uint i) const{assert(i<_max,"oob");return _types[i];}
135   // Extend the mapping: index i maps to Type *n.
136   void map( uint i, const Type *n ) { if( i>=_max ) grow(i); _types[i] = n; }
137   uint Size() const { return _max; }
138 #ifndef PRODUCT
139   void dump() const;
140 #endif
141 };
142 
143 
144 //------------------------------PhaseRemoveUseless-----------------------------
145 // Remove useless nodes from GVN hash-table, worklist, and graph
146 class PhaseRemoveUseless : public Phase {
147 protected:
148   Unique_Node_List _useful;   // Nodes reachable from root
149                               // list is allocated from current resource area
150 public:
151   PhaseRemoveUseless(PhaseGVN *gvn, Unique_Node_List *worklist, PhaseNumber phase_num = Remove_Useless);
152 
153   Unique_Node_List *get_useful() { return &_useful; }
154 };
155 
156 //------------------------------PhaseRenumber----------------------------------
157 // Phase that first performs a PhaseRemoveUseless, then it renumbers compiler
158 // structures accordingly.
159 class PhaseRenumberLive : public PhaseRemoveUseless {
160 protected:
161   Type_Array _new_type_array; // Storage for the updated type information.
162   GrowableArray<int> _old2new_map;
163   Node_List _delayed;
164   bool _is_pass_finished;
165   uint _live_node_count;
166 
167   int update_embedded_ids(Node* n);
168   int new_index(int old_idx);
169 
170 public:
171   PhaseRenumberLive(PhaseGVN* gvn,
172                     Unique_Node_List* worklist, Unique_Node_List* new_worklist,
173                     PhaseNumber phase_num = Remove_Useless_And_Renumber_Live);
174 };
175 
176 
177 //------------------------------PhaseTransform---------------------------------
178 // Phases that analyze, then transform.  Constructing the Phase object does any
179 // global or slow analysis.  The results are cached later for a fast
180 // transformation pass.  When the Phase object is deleted the cached analysis
181 // results are deleted.
182 class PhaseTransform : public Phase {
183 protected:
184   Arena*     _arena;
185   Node_List  _nodes;           // Map old node indices to new nodes.
186   Type_Array _types;           // Map old node indices to Types.
187 
188   // ConNode caches:
189   enum { _icon_min = -1 * HeapWordSize,
190          _icon_max = 16 * HeapWordSize,
191          _lcon_min = _icon_min,
192          _lcon_max = _icon_max,
193          _zcon_max = (uint)T_CONFLICT
194   };
195   ConINode* _icons[_icon_max - _icon_min + 1];   // cached jint constant nodes
196   ConLNode* _lcons[_lcon_max - _lcon_min + 1];   // cached jlong constant nodes
197   ConNode*  _zcons[_zcon_max + 1];               // cached is_zero_type nodes
198   void init_con_caches();
199 
200   // Support both int and long caches because either might be an intptr_t,
201   // so they show up frequently in address computations.
202 
203 public:
204   PhaseTransform( PhaseNumber pnum );
205   PhaseTransform( Arena *arena, PhaseNumber pnum );
206   PhaseTransform( PhaseTransform *phase, PhaseNumber pnum );
207 
208   Arena*      arena()   { return _arena; }
209   Type_Array& types()   { return _types; }
210   void replace_types(Type_Array new_types) {
211     _types = new_types;
212   }
213   // _nodes is used in varying ways by subclasses, which define local accessors
214   uint nodes_size() {
215     return _nodes.size();
216   }
217 
218 public:
219   // Get a previously recorded type for the node n.
220   // This type must already have been recorded.
221   // If you want the type of a very new (untransformed) node,
222   // you must use type_or_null, and test the result for NULL.
223   const Type* type(const Node* n) const {
224     assert(_pnum != Ideal_Loop, "should not be used from PhaseIdealLoop");
225     assert(n != NULL, "must not be null");
226     const Type* t = _types.fast_lookup(n->_idx);
227     assert(t != NULL, "must set before get");
228     return t;
229   }
230   // Get a previously recorded type for the node n,
231   // or else return NULL if there is none.
232   const Type* type_or_null(const Node* n) const {
233     assert(_pnum != Ideal_Loop, "should not be used from PhaseIdealLoop");
234     return _types.fast_lookup(n->_idx);
235   }
236   // Record a type for a node.
237   void    set_type(const Node* n, const Type *t) {
238     assert(t != NULL, "type must not be null");
239     _types.map(n->_idx, t);
240   }
241   // Record an initial type for a node, the node's bottom type.
242   void    set_type_bottom(const Node* n) {
243     // Use this for initialization when bottom_type() (or better) is not handy.
244     // Usually the initialization shoudl be to n->Value(this) instead,
245     // or a hand-optimized value like Type::MEMORY or Type::CONTROL.
246     assert(_types[n->_idx] == NULL, "must set the initial type just once");
247     _types.map(n->_idx, n->bottom_type());
248   }
249   // Make sure the types array is big enough to record a size for the node n.
250   // (In product builds, we never want to do range checks on the types array!)
251   void ensure_type_or_null(const Node* n) {
252     if (n->_idx >= _types.Size())
253       _types.map(n->_idx, NULL);   // Grow the types array as needed.
254   }
255 
256   // Utility functions:
257   const TypeInt*  find_int_type( Node* n);
258   const TypeLong* find_long_type(Node* n);
259   jint  find_int_con( Node* n, jint  value_if_unknown) {
260     const TypeInt* t = find_int_type(n);
261     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
262   }
263   jlong find_long_con(Node* n, jlong value_if_unknown) {
264     const TypeLong* t = find_long_type(n);
265     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
266   }
267 
268   // Make an idealized constant, i.e., one of ConINode, ConPNode, ConFNode, etc.
269   // Same as transform(ConNode::make(t)).
270   ConNode* makecon(const Type* t);
271   virtual ConNode* uncached_makecon(const Type* t)  // override in PhaseValues
272   { ShouldNotCallThis(); return NULL; }
273 
274   // Fast int or long constant.  Same as TypeInt::make(i) or TypeLong::make(l).
275   ConINode* intcon(jint i);
276   ConLNode* longcon(jlong l);
277   ConNode* integercon(jlong l, BasicType bt);
278 
279   // Fast zero or null constant.  Same as makecon(Type::get_zero_type(bt)).
280   ConNode* zerocon(BasicType bt);
281 
282   // Return a node which computes the same function as this node, but
283   // in a faster or cheaper fashion.
284   virtual Node *transform( Node *n ) = 0;
285 
286   // For pessimistic passes, the return type must monotonically narrow.
287   // For optimistic  passes, the return type must monotonically widen.
288   // It is possible to get into a "death march" in either type of pass,
289   // where the types are continually moving but it will take 2**31 or
290   // more steps to converge.  This doesn't happen on most normal loops.
291   //
292   // Here is an example of a deadly loop for an optimistic pass, along
293   // with a partial trace of inferred types:
294   //    x = phi(0,x'); L: x' = x+1; if (x' >= 0) goto L;
295   //    0                 1                join([0..max], 1)
296   //    [0..1]            [1..2]           join([0..max], [1..2])
297   //    [0..2]            [1..3]           join([0..max], [1..3])
298   //      ... ... ...
299   //    [0..max]          [min]u[1..max]   join([0..max], [min..max])
300   //    [0..max] ==> fixpoint
301   // We would have proven, the hard way, that the iteration space is all
302   // non-negative ints, with the loop terminating due to 32-bit overflow.
303   //
304   // Here is the corresponding example for a pessimistic pass:
305   //    x = phi(0,x'); L: x' = x-1; if (x' >= 0) goto L;
306   //    int               int              join([0..max], int)
307   //    [0..max]          [-1..max-1]      join([0..max], [-1..max-1])
308   //    [0..max-1]        [-1..max-2]      join([0..max], [-1..max-2])
309   //      ... ... ...
310   //    [0..1]            [-1..0]          join([0..max], [-1..0])
311   //    0                 -1               join([0..max], -1)
312   //    0 == fixpoint
313   // We would have proven, the hard way, that the iteration space is {0}.
314   // (Usually, other optimizations will make the "if (x >= 0)" fold up
315   // before we get into trouble.  But not always.)
316   //
317   // It's a pleasant thing to observe that the pessimistic pass
318   // will make short work of the optimistic pass's deadly loop,
319   // and vice versa.  That is a good example of the complementary
320   // purposes of the CCP (optimistic) vs. GVN (pessimistic) phases.
321   //
322   // In any case, only widen or narrow a few times before going to the
323   // correct flavor of top or bottom.
324   //
325   // This call only needs to be made once as the data flows around any
326   // given cycle.  We do it at Phis, and nowhere else.
327   // The types presented are the new type of a phi (computed by PhiNode::Value)
328   // and the previously computed type, last time the phi was visited.
329   //
330   // The third argument is upper limit for the saturated value,
331   // if the phase wishes to widen the new_type.
332   // If the phase is narrowing, the old type provides a lower limit.
333   // Caller guarantees that old_type and new_type are no higher than limit_type.
334   virtual const Type* saturate(const Type* new_type, const Type* old_type,
335                                const Type* limit_type) const
336   { ShouldNotCallThis(); return NULL; }
337 
338   // true if CFG node d dominates CFG node n
339   virtual bool is_dominator(Node *d, Node *n) { fatal("unimplemented for this pass"); return false; };
340 
341 #ifndef PRODUCT
342   void dump_old2new_map() const;
343   void dump_new( uint new_lidx ) const;
344   void dump_types() const;
345   void dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl = true);
346   void dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited);
347 
348   uint   _count_progress;       // For profiling, count transforms that make progress
349   void   set_progress()        { ++_count_progress; assert( allow_progress(),"No progress allowed during verification"); }
350   void   clear_progress()      { _count_progress = 0; }
351   uint   made_progress() const { return _count_progress; }
352 
353   uint   _count_transforms;     // For profiling, count transforms performed
354   void   set_transforms()      { ++_count_transforms; }
355   void   clear_transforms()    { _count_transforms = 0; }
356   uint   made_transforms() const{ return _count_transforms; }
357 
358   bool   _allow_progress;      // progress not allowed during verification pass
359   void   set_allow_progress(bool allow) { _allow_progress = allow; }
360   bool   allow_progress()               { return _allow_progress; }
361 #endif
362 };
363 
364 //------------------------------PhaseValues------------------------------------
365 // Phase infrastructure to support values
366 class PhaseValues : public PhaseTransform {
367 protected:
368   NodeHash  _table;             // Hash table for value-numbering
369   bool      _iterGVN;
370 public:
371   PhaseValues(Arena* arena, uint est_max_size);
372   PhaseValues(PhaseValues* pt);
373   NOT_PRODUCT(~PhaseValues();)
374   PhaseIterGVN* is_IterGVN() { return (_iterGVN) ? (PhaseIterGVN*)this : NULL; }
375 
376   // Some Ideal and other transforms delete --> modify --> insert values
377   bool   hash_delete(Node* n)     { return _table.hash_delete(n); }
378   void   hash_insert(Node* n)     { _table.hash_insert(n); }
379   Node*  hash_find_insert(Node* n){ return _table.hash_find_insert(n); }
380   Node*  hash_find(const Node* n) { return _table.hash_find(n); }
381 
382   // Used after parsing to eliminate values that are no longer in program
383   void   remove_useless_nodes(VectorSet &useful) {
384     _table.remove_useless_nodes(useful);
385     // this may invalidate cached cons so reset the cache
386     init_con_caches();
387   }
388 
389   virtual ConNode* uncached_makecon(const Type* t);  // override from PhaseTransform
390 
391   const Type* saturate(const Type* new_type, const Type* old_type,
392                        const Type* limit_type) const
393   { return new_type; }
394 
395 #ifndef PRODUCT
396   uint   _count_new_values;     // For profiling, count new values produced
397   void    inc_new_values()        { ++_count_new_values; }
398   void    clear_new_values()      { _count_new_values = 0; }
399   uint    made_new_values() const { return _count_new_values; }
400 #endif
401 };
402 
403 
404 //------------------------------PhaseGVN---------------------------------------
405 // Phase for performing local, pessimistic GVN-style optimizations.
406 class PhaseGVN : public PhaseValues {
407 protected:
408   bool is_dominator_helper(Node *d, Node *n, bool linear_only);
409 
410 public:
411   PhaseGVN( Arena *arena, uint est_max_size ) : PhaseValues( arena, est_max_size ) {}
412   PhaseGVN( PhaseGVN *gvn ) : PhaseValues( gvn ) {}
413 
414   // Return a node which computes the same function as this node, but
415   // in a faster or cheaper fashion.
416   Node  *transform( Node *n );
417   Node  *transform_no_reclaim( Node *n );
418   virtual void record_for_igvn(Node *n) {
419     C->record_for_igvn(n);
420   }
421 
422   void replace_with(PhaseGVN* gvn) {
423     _table.replace_with(&gvn->_table);
424     _types = gvn->_types;
425   }
426 
427   bool is_dominator(Node *d, Node *n) { return is_dominator_helper(d, n, true); }
428 
429   // Helper to call Node::Ideal() and BarrierSetC2::ideal_node().
430   Node* apply_ideal(Node* i, bool can_reshape);
431 
432 #ifdef ASSERT
433   void dump_infinite_loop_info(Node* n, const char* where);
434   // Check for a simple dead loop when a data node references itself.
435   void dead_loop_check(Node *n);
436 #endif
437 };
438 
439 //------------------------------PhaseIterGVN-----------------------------------
440 // Phase for iteratively performing local, pessimistic GVN-style optimizations.
441 // and ideal transformations on the graph.
442 class PhaseIterGVN : public PhaseGVN {
443 private:
444   bool _delay_transform;  // When true simply register the node when calling transform
445                           // instead of actually optimizing it
446 
447   // Idealize old Node 'n' with respect to its inputs and its value
448   virtual Node *transform_old( Node *a_node );
449 
450   // Subsume users of node 'old' into node 'nn'
451   void subsume_node( Node *old, Node *nn );
452 
453   Node_Stack _stack;      // Stack used to avoid recursion
454 protected:
455 
456   // Shuffle worklist, for stress testing
457   void shuffle_worklist();
458 
459   virtual const Type* saturate(const Type* new_type, const Type* old_type,
460                                const Type* limit_type) const;
461   // Usually returns new_type.  Returns old_type if new_type is only a slight
462   // improvement, such that it would take many (>>10) steps to reach 2**32.
463 
464 public:
465   PhaseIterGVN(PhaseIterGVN* igvn); // Used by CCP constructor
466   PhaseIterGVN(PhaseGVN* gvn); // Used after Parser
467 
468   // Idealize new Node 'n' with respect to its inputs and its value
469   virtual Node *transform( Node *a_node );
470   virtual void record_for_igvn(Node *n) { }
471 
472   Unique_Node_List _worklist;       // Iterative worklist
473 
474   // Given def-use info and an initial worklist, apply Node::Ideal,
475   // Node::Value, Node::Identity, hash-based value numbering, Node::Ideal_DU
476   // and dominator info to a fixed point.
477   void optimize();
478 
479 #ifndef PRODUCT
480   void trace_PhaseIterGVN(Node* n, Node* nn, const Type* old_type);
481   void init_verifyPhaseIterGVN();
482   void verify_PhaseIterGVN();
483 #endif
484 
485 #ifdef ASSERT
486   void dump_infinite_loop_info(Node* n, const char* where);
487   void trace_PhaseIterGVN_verbose(Node* n, int num_processed);
488 #endif
489 
490   // Register a new node with the iter GVN pass without transforming it.
491   // Used when we need to restructure a Region/Phi area and all the Regions
492   // and Phis need to complete this one big transform before any other
493   // transforms can be triggered on the region.
494   // Optional 'orig' is an earlier version of this node.
495   // It is significant only for debugging and profiling.
496   Node* register_new_node_with_optimizer(Node* n, Node* orig = NULL);
497 
498   // Kill a globally dead Node.  All uses are also globally dead and are
499   // aggressively trimmed.
500   void remove_globally_dead_node( Node *dead );
501 
502   // Kill all inputs to a dead node, recursively making more dead nodes.
503   // The Node must be dead locally, i.e., have no uses.
504   void remove_dead_node( Node *dead ) {
505     assert(dead->outcnt() == 0 && !dead->is_top(), "node must be dead");
506     remove_globally_dead_node(dead);
507   }
508 
509   // Add users of 'n' to worklist
510   void add_users_to_worklist0( Node *n );
511   void add_users_to_worklist ( Node *n );
512 
513   // Replace old node with new one.
514   void replace_node( Node *old, Node *nn ) {
515     add_users_to_worklist(old);
516     hash_delete(old); // Yank from hash before hacking edges
517     subsume_node(old, nn);
518   }
519 
520   // Delayed node rehash: remove a node from the hash table and rehash it during
521   // next optimizing pass
522   void rehash_node_delayed(Node* n) {
523     hash_delete(n);
524     _worklist.push(n);
525   }
526 
527   // Replace ith edge of "n" with "in"
528   void replace_input_of(Node* n, int i, Node* in) {
529     rehash_node_delayed(n);
530     n->set_req_X(i, in, this);
531   }
532 
533   // Delete ith edge of "n"
534   void delete_input_of(Node* n, int i) {
535     rehash_node_delayed(n);
536     n->del_req(i);
537   }
538 
539   bool delay_transform() const { return _delay_transform; }
540 
541   void set_delay_transform(bool delay) {
542     _delay_transform = delay;
543   }
544 
545   void remove_speculative_types();
546   void check_no_speculative_types() {
547     _table.check_no_speculative_types();
548   }
549 
550   bool is_dominator(Node *d, Node *n) { return is_dominator_helper(d, n, false); }
551   bool no_dependent_zero_check(Node* n) const;
552 
553 #ifndef PRODUCT
554 protected:
555   // Sub-quadratic implementation of VerifyIterativeGVN.
556   julong _verify_counter;
557   julong _verify_full_passes;
558   enum { _verify_window_size = 30 };
559   Node* _verify_window[_verify_window_size];
560   void verify_step(Node* n);
561 #endif
562 };
563 
564 //------------------------------PhaseCCP---------------------------------------
565 // Phase for performing global Conditional Constant Propagation.
566 // Should be replaced with combined CCP & GVN someday.
567 class PhaseCCP : public PhaseIterGVN {
568   // Non-recursive.  Use analysis to transform single Node.
569   virtual Node *transform_once( Node *n );
570 
571 public:
572   PhaseCCP( PhaseIterGVN *igvn ); // Compute conditional constants
573   NOT_PRODUCT( ~PhaseCCP(); )
574 
575   // Worklist algorithm identifies constants
576   void analyze();
577   // Recursive traversal of program.  Used analysis to modify program.
578   virtual Node *transform( Node *n );
579   // Do any transformation after analysis
580   void          do_transform();
581 
582   virtual const Type* saturate(const Type* new_type, const Type* old_type,
583                                const Type* limit_type) const;
584   // Returns new_type->widen(old_type), which increments the widen bits until
585   // giving up with TypeInt::INT or TypeLong::LONG.
586   // Result is clipped to limit_type if necessary.
587 
588 #ifndef PRODUCT
589   static uint _total_invokes;    // For profiling, count invocations
590   void    inc_invokes()          { ++PhaseCCP::_total_invokes; }
591 
592   static uint _total_constants;  // For profiling, count constants found
593   uint   _count_constants;
594   void    clear_constants()      { _count_constants = 0; }
595   void    inc_constants()        { ++_count_constants; }
596   uint    count_constants() const { return _count_constants; }
597 
598   static void print_statistics();
599 #endif
600 };
601 
602 
603 //------------------------------PhasePeephole----------------------------------
604 // Phase for performing peephole optimizations on register allocated basic blocks.
605 class PhasePeephole : public PhaseTransform {
606   PhaseRegAlloc *_regalloc;
607   PhaseCFG     &_cfg;
608   // Recursive traversal of program.  Pure function is unused in this phase
609   virtual Node *transform( Node *n );
610 
611 public:
612   PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg );
613   NOT_PRODUCT( ~PhasePeephole(); )
614 
615   // Do any transformation after analysis
616   void          do_transform();
617 
618 #ifndef PRODUCT
619   static uint _total_peepholes;  // For profiling, count peephole rules applied
620   uint   _count_peepholes;
621   void    clear_peepholes()      { _count_peepholes = 0; }
622   void    inc_peepholes()        { ++_count_peepholes; }
623   uint    count_peepholes() const { return _count_peepholes; }
624 
625   static void print_statistics();
626 #endif
627 };
628 
629 #endif // SHARE_OPTO_PHASEX_HPP