Mon, 25 May 2020 14:24:27 +0800
8244407: JVM crashes after transformation in C2 IdealLoopTree::split_fall_in
Reviewed-by: thartmann, kvn, andrew
Contributed-by: zhouyong44@huawei.com
1 /*
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25 #ifndef SHARE_VM_OPTO_PHASEX_HPP
26 #define SHARE_VM_OPTO_PHASEX_HPP
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"
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;
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
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); }
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 }
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
98 Node *sentinel() { return _sentinel; }
100 #ifndef PRODUCT
101 Node *find_index(uint idx); // For debugging
102 void dump(); // For debugging, dump statistics
103 #endif
104 uint _grows; // For debugging, count of table grow()s
105 uint _look_probes; // For debugging, count of hash probes
106 uint _lookup_hits; // For debugging, count of hash_finds
107 uint _lookup_misses; // For debugging, count of hash_finds
108 uint _insert_probes; // For debugging, count of hash probes
109 uint _delete_probes; // For debugging, count of hash probes for deletes
110 uint _delete_hits; // For debugging, count of hash probes for deletes
111 uint _delete_misses; // For debugging, count of hash probes for deletes
112 uint _total_inserts; // For debugging, total inserts into hash table
113 uint _total_insert_probes; // For debugging, total probes while inserting
114 };
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 };
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);
153 Unique_Node_List *get_useful() { return &_useful; }
154 };
156 //------------------------------PhaseRenumber----------------------------------
157 // Phase that first performs a PhaseRemoveUseless, then it renumbers compiler
158 // structures accordingly.
159 class PhaseRenumberLive : public PhaseRemoveUseless {
160 public:
161 PhaseRenumberLive(PhaseGVN* gvn,
162 Unique_Node_List* worklist, Unique_Node_List* new_worklist,
163 PhaseNumber phase_num = Remove_Useless_And_Renumber_Live);
164 };
167 //------------------------------PhaseTransform---------------------------------
168 // Phases that analyze, then transform. Constructing the Phase object does any
169 // global or slow analysis. The results are cached later for a fast
170 // transformation pass. When the Phase object is deleted the cached analysis
171 // results are deleted.
172 class PhaseTransform : public Phase {
173 protected:
174 Arena* _arena;
175 Node_List _nodes; // Map old node indices to new nodes.
176 Type_Array _types; // Map old node indices to Types.
178 // ConNode caches:
179 enum { _icon_min = -1 * HeapWordSize,
180 _icon_max = 16 * HeapWordSize,
181 _lcon_min = _icon_min,
182 _lcon_max = _icon_max,
183 _zcon_max = (uint)T_CONFLICT
184 };
185 ConINode* _icons[_icon_max - _icon_min + 1]; // cached jint constant nodes
186 ConLNode* _lcons[_lcon_max - _lcon_min + 1]; // cached jlong constant nodes
187 ConNode* _zcons[_zcon_max + 1]; // cached is_zero_type nodes
188 void init_con_caches();
190 // Support both int and long caches because either might be an intptr_t,
191 // so they show up frequently in address computations.
193 public:
194 PhaseTransform( PhaseNumber pnum );
195 PhaseTransform( Arena *arena, PhaseNumber pnum );
196 PhaseTransform( PhaseTransform *phase, PhaseNumber pnum );
198 Arena* arena() { return _arena; }
199 Type_Array& types() { return _types; }
200 void replace_types(Type_Array new_types) {
201 _types = new_types;
202 }
203 // _nodes is used in varying ways by subclasses, which define local accessors
204 uint nodes_size() {
205 return _nodes.size();
206 }
208 public:
209 // Get a previously recorded type for the node n.
210 // This type must already have been recorded.
211 // If you want the type of a very new (untransformed) node,
212 // you must use type_or_null, and test the result for NULL.
213 const Type* type(const Node* n) const {
214 assert(n != NULL, "must not be null");
215 const Type* t = _types.fast_lookup(n->_idx);
216 assert(t != NULL, "must set before get");
217 return t;
218 }
219 // Get a previously recorded type for the node n,
220 // or else return NULL if there is none.
221 const Type* type_or_null(const Node* n) const {
222 return _types.fast_lookup(n->_idx);
223 }
224 // Record a type for a node.
225 void set_type(const Node* n, const Type *t) {
226 assert(t != NULL, "type must not be null");
227 _types.map(n->_idx, t);
228 }
229 // Record an initial type for a node, the node's bottom type.
230 void set_type_bottom(const Node* n) {
231 // Use this for initialization when bottom_type() (or better) is not handy.
232 // Usually the initialization shoudl be to n->Value(this) instead,
233 // or a hand-optimized value like Type::MEMORY or Type::CONTROL.
234 assert(_types[n->_idx] == NULL, "must set the initial type just once");
235 _types.map(n->_idx, n->bottom_type());
236 }
237 // Make sure the types array is big enough to record a size for the node n.
238 // (In product builds, we never want to do range checks on the types array!)
239 void ensure_type_or_null(const Node* n) {
240 if (n->_idx >= _types.Size())
241 _types.map(n->_idx, NULL); // Grow the types array as needed.
242 }
244 // Utility functions:
245 const TypeInt* find_int_type( Node* n);
246 const TypeLong* find_long_type(Node* n);
247 jint find_int_con( Node* n, jint value_if_unknown) {
248 const TypeInt* t = find_int_type(n);
249 return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
250 }
251 jlong find_long_con(Node* n, jlong value_if_unknown) {
252 const TypeLong* t = find_long_type(n);
253 return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
254 }
256 // Make an idealized constant, i.e., one of ConINode, ConPNode, ConFNode, etc.
257 // Same as transform(ConNode::make(t)).
258 ConNode* makecon(const Type* t);
259 virtual ConNode* uncached_makecon(const Type* t) // override in PhaseValues
260 { ShouldNotCallThis(); return NULL; }
262 // Fast int or long constant. Same as TypeInt::make(i) or TypeLong::make(l).
263 ConINode* intcon(jint i);
264 ConLNode* longcon(jlong l);
266 // Fast zero or null constant. Same as makecon(Type::get_zero_type(bt)).
267 ConNode* zerocon(BasicType bt);
269 // Return a node which computes the same function as this node, but
270 // in a faster or cheaper fashion.
271 virtual Node *transform( Node *n ) = 0;
273 // Return whether two Nodes are equivalent.
274 // Must not be recursive, since the recursive version is built from this.
275 // For pessimistic optimizations this is simply pointer equivalence.
276 bool eqv(const Node* n1, const Node* n2) const { return n1 == n2; }
278 // For pessimistic passes, the return type must monotonically narrow.
279 // For optimistic passes, the return type must monotonically widen.
280 // It is possible to get into a "death march" in either type of pass,
281 // where the types are continually moving but it will take 2**31 or
282 // more steps to converge. This doesn't happen on most normal loops.
283 //
284 // Here is an example of a deadly loop for an optimistic pass, along
285 // with a partial trace of inferred types:
286 // x = phi(0,x'); L: x' = x+1; if (x' >= 0) goto L;
287 // 0 1 join([0..max], 1)
288 // [0..1] [1..2] join([0..max], [1..2])
289 // [0..2] [1..3] join([0..max], [1..3])
290 // ... ... ...
291 // [0..max] [min]u[1..max] join([0..max], [min..max])
292 // [0..max] ==> fixpoint
293 // We would have proven, the hard way, that the iteration space is all
294 // non-negative ints, with the loop terminating due to 32-bit overflow.
295 //
296 // Here is the corresponding example for a pessimistic pass:
297 // x = phi(0,x'); L: x' = x-1; if (x' >= 0) goto L;
298 // int int join([0..max], int)
299 // [0..max] [-1..max-1] join([0..max], [-1..max-1])
300 // [0..max-1] [-1..max-2] join([0..max], [-1..max-2])
301 // ... ... ...
302 // [0..1] [-1..0] join([0..max], [-1..0])
303 // 0 -1 join([0..max], -1)
304 // 0 == fixpoint
305 // We would have proven, the hard way, that the iteration space is {0}.
306 // (Usually, other optimizations will make the "if (x >= 0)" fold up
307 // before we get into trouble. But not always.)
308 //
309 // It's a pleasant thing to observe that the pessimistic pass
310 // will make short work of the optimistic pass's deadly loop,
311 // and vice versa. That is a good example of the complementary
312 // purposes of the CCP (optimistic) vs. GVN (pessimistic) phases.
313 //
314 // In any case, only widen or narrow a few times before going to the
315 // correct flavor of top or bottom.
316 //
317 // This call only needs to be made once as the data flows around any
318 // given cycle. We do it at Phis, and nowhere else.
319 // The types presented are the new type of a phi (computed by PhiNode::Value)
320 // and the previously computed type, last time the phi was visited.
321 //
322 // The third argument is upper limit for the saturated value,
323 // if the phase wishes to widen the new_type.
324 // If the phase is narrowing, the old type provides a lower limit.
325 // Caller guarantees that old_type and new_type are no higher than limit_type.
326 virtual const Type* saturate(const Type* new_type, const Type* old_type,
327 const Type* limit_type) const
328 { ShouldNotCallThis(); return NULL; }
330 #ifndef PRODUCT
331 void dump_old2new_map() const;
332 void dump_new( uint new_lidx ) const;
333 void dump_types() const;
334 void dump_nodes_and_types(const Node *root, uint depth, bool only_ctrl = true);
335 void dump_nodes_and_types_recur( const Node *n, uint depth, bool only_ctrl, VectorSet &visited);
337 uint _count_progress; // For profiling, count transforms that make progress
338 void set_progress() { ++_count_progress; assert( allow_progress(),"No progress allowed during verification"); }
339 void clear_progress() { _count_progress = 0; }
340 uint made_progress() const { return _count_progress; }
342 uint _count_transforms; // For profiling, count transforms performed
343 void set_transforms() { ++_count_transforms; }
344 void clear_transforms() { _count_transforms = 0; }
345 uint made_transforms() const{ return _count_transforms; }
347 bool _allow_progress; // progress not allowed during verification pass
348 void set_allow_progress(bool allow) { _allow_progress = allow; }
349 bool allow_progress() { return _allow_progress; }
350 #endif
351 };
353 //------------------------------PhaseValues------------------------------------
354 // Phase infrastructure to support values
355 class PhaseValues : public PhaseTransform {
356 protected:
357 NodeHash _table; // Hash table for value-numbering
359 public:
360 PhaseValues( Arena *arena, uint est_max_size );
361 PhaseValues( PhaseValues *pt );
362 PhaseValues( PhaseValues *ptv, const char *dummy );
363 NOT_PRODUCT( ~PhaseValues(); )
364 virtual PhaseIterGVN *is_IterGVN() { return 0; }
366 // Some Ideal and other transforms delete --> modify --> insert values
367 bool hash_delete(Node *n) { return _table.hash_delete(n); }
368 void hash_insert(Node *n) { _table.hash_insert(n); }
369 Node *hash_find_insert(Node *n){ return _table.hash_find_insert(n); }
370 Node *hash_find(const Node *n) { return _table.hash_find(n); }
372 // Used after parsing to eliminate values that are no longer in program
373 void remove_useless_nodes(VectorSet &useful) {
374 _table.remove_useless_nodes(useful);
375 // this may invalidate cached cons so reset the cache
376 init_con_caches();
377 }
379 virtual ConNode* uncached_makecon(const Type* t); // override from PhaseTransform
381 virtual const Type* saturate(const Type* new_type, const Type* old_type,
382 const Type* limit_type) const
383 { return new_type; }
385 #ifndef PRODUCT
386 uint _count_new_values; // For profiling, count new values produced
387 void inc_new_values() { ++_count_new_values; }
388 void clear_new_values() { _count_new_values = 0; }
389 uint made_new_values() const { return _count_new_values; }
390 #endif
391 };
394 //------------------------------PhaseGVN---------------------------------------
395 // Phase for performing local, pessimistic GVN-style optimizations.
396 class PhaseGVN : public PhaseValues {
397 public:
398 PhaseGVN( Arena *arena, uint est_max_size ) : PhaseValues( arena, est_max_size ) {}
399 PhaseGVN( PhaseGVN *gvn ) : PhaseValues( gvn ) {}
400 PhaseGVN( PhaseGVN *gvn, const char *dummy ) : PhaseValues( gvn, dummy ) {}
402 // Return a node which computes the same function as this node, but
403 // in a faster or cheaper fashion.
404 Node *transform( Node *n );
405 Node *transform_no_reclaim( Node *n );
407 void replace_with(PhaseGVN* gvn) {
408 _table.replace_with(&gvn->_table);
409 _types = gvn->_types;
410 }
412 // Check for a simple dead loop when a data node references itself.
413 DEBUG_ONLY(void dead_loop_check(Node *n);)
414 };
416 //------------------------------PhaseIterGVN-----------------------------------
417 // Phase for iteratively performing local, pessimistic GVN-style optimizations.
418 // and ideal transformations on the graph.
419 class PhaseIterGVN : public PhaseGVN {
420 private:
421 bool _delay_transform; // When true simply register the node when calling transform
422 // instead of actually optimizing it
424 // Idealize old Node 'n' with respect to its inputs and its value
425 virtual Node *transform_old( Node *a_node );
427 // Subsume users of node 'old' into node 'nn'
428 void subsume_node( Node *old, Node *nn );
430 Node_Stack _stack; // Stack used to avoid recursion
432 protected:
434 // Idealize new Node 'n' with respect to its inputs and its value
435 virtual Node *transform( Node *a_node );
437 // Warm up hash table, type table and initial worklist
438 void init_worklist( Node *a_root );
440 virtual const Type* saturate(const Type* new_type, const Type* old_type,
441 const Type* limit_type) const;
442 // Usually returns new_type. Returns old_type if new_type is only a slight
443 // improvement, such that it would take many (>>10) steps to reach 2**32.
445 public:
446 PhaseIterGVN( PhaseIterGVN *igvn ); // Used by CCP constructor
447 PhaseIterGVN( PhaseGVN *gvn ); // Used after Parser
448 PhaseIterGVN( PhaseIterGVN *igvn, const char *dummy ); // Used after +VerifyOpto
450 virtual PhaseIterGVN *is_IterGVN() { return this; }
452 Unique_Node_List _worklist; // Iterative worklist
454 // Given def-use info and an initial worklist, apply Node::Ideal,
455 // Node::Value, Node::Identity, hash-based value numbering, Node::Ideal_DU
456 // and dominator info to a fixed point.
457 void optimize();
459 // Register a new node with the iter GVN pass without transforming it.
460 // Used when we need to restructure a Region/Phi area and all the Regions
461 // and Phis need to complete this one big transform before any other
462 // transforms can be triggered on the region.
463 // Optional 'orig' is an earlier version of this node.
464 // It is significant only for debugging and profiling.
465 Node* register_new_node_with_optimizer(Node* n, Node* orig = NULL);
467 // Kill a globally dead Node. All uses are also globally dead and are
468 // aggressively trimmed.
469 void remove_globally_dead_node( Node *dead );
471 // Kill all inputs to a dead node, recursively making more dead nodes.
472 // The Node must be dead locally, i.e., have no uses.
473 void remove_dead_node( Node *dead ) {
474 assert(dead->outcnt() == 0 && !dead->is_top(), "node must be dead");
475 remove_globally_dead_node(dead);
476 }
478 // Add users of 'n' to worklist
479 void add_users_to_worklist0( Node *n );
480 void add_users_to_worklist ( Node *n );
482 // Replace old node with new one.
483 void replace_node( Node *old, Node *nn ) {
484 add_users_to_worklist(old);
485 hash_delete(old); // Yank from hash before hacking edges
486 subsume_node(old, nn);
487 }
489 // Delayed node rehash: remove a node from the hash table and rehash it during
490 // next optimizing pass
491 void rehash_node_delayed(Node* n) {
492 hash_delete(n);
493 _worklist.push(n);
494 }
496 // Replace ith edge of "n" with "in"
497 void replace_input_of(Node* n, int i, Node* in) {
498 rehash_node_delayed(n);
499 n->set_req(i, in);
500 }
502 // Delete ith edge of "n"
503 void delete_input_of(Node* n, int i) {
504 rehash_node_delayed(n);
505 n->del_req(i);
506 }
508 bool delay_transform() const { return _delay_transform; }
510 void set_delay_transform(bool delay) {
511 _delay_transform = delay;
512 }
514 // Clone loop predicates. Defined in loopTransform.cpp.
515 Node* clone_loop_predicates(Node* old_entry, Node* new_entry, bool clone_limit_check);
516 // Create a new if below new_entry for the predicate to be cloned
517 ProjNode* create_new_if_for_predicate(ProjNode* cont_proj, Node* new_entry,
518 Deoptimization::DeoptReason reason);
520 void remove_speculative_types();
521 void check_no_speculative_types() {
522 _table.check_no_speculative_types();
523 }
525 #ifndef PRODUCT
526 protected:
527 // Sub-quadratic implementation of VerifyIterativeGVN.
528 julong _verify_counter;
529 julong _verify_full_passes;
530 enum { _verify_window_size = 30 };
531 Node* _verify_window[_verify_window_size];
532 void verify_step(Node* n);
533 #endif
534 };
536 //------------------------------PhaseCCP---------------------------------------
537 // Phase for performing global Conditional Constant Propagation.
538 // Should be replaced with combined CCP & GVN someday.
539 class PhaseCCP : public PhaseIterGVN {
540 // Non-recursive. Use analysis to transform single Node.
541 virtual Node *transform_once( Node *n );
543 public:
544 PhaseCCP( PhaseIterGVN *igvn ); // Compute conditional constants
545 NOT_PRODUCT( ~PhaseCCP(); )
547 // Worklist algorithm identifies constants
548 void analyze();
549 // Recursive traversal of program. Used analysis to modify program.
550 virtual Node *transform( Node *n );
551 // Do any transformation after analysis
552 void do_transform();
554 virtual const Type* saturate(const Type* new_type, const Type* old_type,
555 const Type* limit_type) const;
556 // Returns new_type->widen(old_type), which increments the widen bits until
557 // giving up with TypeInt::INT or TypeLong::LONG.
558 // Result is clipped to limit_type if necessary.
560 #ifndef PRODUCT
561 static uint _total_invokes; // For profiling, count invocations
562 void inc_invokes() { ++PhaseCCP::_total_invokes; }
564 static uint _total_constants; // For profiling, count constants found
565 uint _count_constants;
566 void clear_constants() { _count_constants = 0; }
567 void inc_constants() { ++_count_constants; }
568 uint count_constants() const { return _count_constants; }
570 static void print_statistics();
571 #endif
572 };
575 //------------------------------PhasePeephole----------------------------------
576 // Phase for performing peephole optimizations on register allocated basic blocks.
577 class PhasePeephole : public PhaseTransform {
578 PhaseRegAlloc *_regalloc;
579 PhaseCFG &_cfg;
580 // Recursive traversal of program. Pure function is unused in this phase
581 virtual Node *transform( Node *n );
583 public:
584 PhasePeephole( PhaseRegAlloc *regalloc, PhaseCFG &cfg );
585 NOT_PRODUCT( ~PhasePeephole(); )
587 // Do any transformation after analysis
588 void do_transform();
590 #ifndef PRODUCT
591 static uint _total_peepholes; // For profiling, count peephole rules applied
592 uint _count_peepholes;
593 void clear_peepholes() { _count_peepholes = 0; }
594 void inc_peepholes() { ++_count_peepholes; }
595 uint count_peepholes() const { return _count_peepholes; }
597 static void print_statistics();
598 #endif
599 };
601 #endif // SHARE_VM_OPTO_PHASEX_HPP