1 /*
2 * Copyright 2000-2008 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25
26 class ciTypeFlow : public ResourceObj {
27 private:
28 ciEnv* _env;
29 ciMethod* _method;
30 ciMethodBlocks* _methodBlocks;
31 int _osr_bci;
32
33 // information cached from the method:
34 int _max_locals;
35 int _max_stack;
36 int _code_size;
37 bool _has_irreducible_entry;
38
39 const char* _failure_reason;
40
41 public:
42 class StateVector;
43 class Loop;
44 class Block;
45
46 // Build a type flow analyzer
47 // Do an OSR analysis if osr_bci >= 0.
48 ciTypeFlow(ciEnv* env, ciMethod* method, int osr_bci = InvocationEntryBci);
49
50 // Accessors
51 ciMethod* method() const { return _method; }
52 ciEnv* env() { return _env; }
53 Arena* arena() { return _env->arena(); }
54 bool is_osr_flow() const{ return _osr_bci != InvocationEntryBci; }
55 int start_bci() const { return is_osr_flow()? _osr_bci: 0; }
56 int max_locals() const { return _max_locals; }
57 int max_stack() const { return _max_stack; }
58 int max_cells() const { return _max_locals + _max_stack; }
59 int code_size() const { return _code_size; }
60 bool has_irreducible_entry() const { return _has_irreducible_entry; }
61
62 // Represents information about an "active" jsr call. This
63 // class represents a call to the routine at some entry address
64 // with some distinct return address.
65 class JsrRecord : public ResourceObj {
66 private:
67 int _entry_address;
68 int _return_address;
69 public:
70 JsrRecord(int entry_address, int return_address) {
71 _entry_address = entry_address;
72 _return_address = return_address;
73 }
74
75 int entry_address() const { return _entry_address; }
76 int return_address() const { return _return_address; }
77
78 void print_on(outputStream* st) const {
79 #ifndef PRODUCT
80 st->print("%d->%d", entry_address(), return_address());
81 #endif
82 }
83 };
84
85 // A JsrSet represents some set of JsrRecords. This class
86 // is used to record a set of all jsr routines which we permit
87 // execution to return (ret) from.
88 //
89 // During abstract interpretation, JsrSets are used to determine
90 // whether two paths which reach a given block are unique, and
91 // should be cloned apart, or are compatible, and should merge
92 // together.
93 //
94 // Note that different amounts of effort can be expended determining
95 // if paths are compatible. <DISCUSSION>
96 class JsrSet : public ResourceObj {
97 private:
98 GrowableArray<JsrRecord*>* _set;
99
100 JsrRecord* record_at(int i) {
101 return _set->at(i);
102 }
103
104 // Insert the given JsrRecord into the JsrSet, maintaining the order
105 // of the set and replacing any element with the same entry address.
106 void insert_jsr_record(JsrRecord* record);
107
108 // Remove the JsrRecord with the given return address from the JsrSet.
109 void remove_jsr_record(int return_address);
110
111 public:
112 JsrSet(Arena* arena, int default_len = 4);
113
114 // Copy this JsrSet.
115 void copy_into(JsrSet* jsrs);
116
117 // Is this JsrSet compatible with some other JsrSet?
118 bool is_compatible_with(JsrSet* other);
119
120 // Apply the effect of a single bytecode to the JsrSet.
121 void apply_control(ciTypeFlow* analyzer,
122 ciBytecodeStream* str,
123 StateVector* state);
124
125 // What is the cardinality of this set?
126 int size() const { return _set->length(); }
127
128 void print_on(outputStream* st) const PRODUCT_RETURN;
129 };
130
131 class LocalSet VALUE_OBJ_CLASS_SPEC {
132 private:
133 enum Constants { max = 63 };
134 uint64_t _bits;
135 public:
136 LocalSet() : _bits(0) {}
137 void add(uint32_t i) { if (i < (uint32_t)max) _bits |= (1LL << i); }
138 void add(LocalSet* ls) { _bits |= ls->_bits; }
139 bool test(uint32_t i) const { return i < (uint32_t)max ? (_bits>>i)&1U : true; }
140 void clear() { _bits = 0; }
141 void print_on(outputStream* st, int limit) const PRODUCT_RETURN;
142 };
143
144 // Used as a combined index for locals and temps
145 enum Cell {
146 Cell_0, Cell_max = INT_MAX
147 };
148
149 // A StateVector summarizes the type information at some
150 // point in the program
151 class StateVector : public ResourceObj {
152 private:
153 ciType** _types;
154 int _stack_size;
155 int _monitor_count;
156 ciTypeFlow* _outer;
157
158 int _trap_bci;
159 int _trap_index;
160
161 LocalSet _def_locals; // For entire block
162
163 static ciType* type_meet_internal(ciType* t1, ciType* t2, ciTypeFlow* analyzer);
164
165 public:
166 // Special elements in our type lattice.
167 enum {
168 T_TOP = T_VOID, // why not?
169 T_BOTTOM = T_CONFLICT,
170 T_LONG2 = T_SHORT, // 2nd word of T_LONG
171 T_DOUBLE2 = T_CHAR, // 2nd word of T_DOUBLE
172 T_NULL = T_BYTE // for now.
173 };
174 static ciType* top_type() { return ciType::make((BasicType)T_TOP); }
175 static ciType* bottom_type() { return ciType::make((BasicType)T_BOTTOM); }
176 static ciType* long2_type() { return ciType::make((BasicType)T_LONG2); }
177 static ciType* double2_type(){ return ciType::make((BasicType)T_DOUBLE2); }
178 static ciType* null_type() { return ciType::make((BasicType)T_NULL); }
179
180 static ciType* half_type(ciType* t) {
181 switch (t->basic_type()) {
182 case T_LONG: return long2_type();
183 case T_DOUBLE: return double2_type();
184 default: ShouldNotReachHere(); return NULL;
185 }
186 }
187
188 // The meet operation for our type lattice.
189 ciType* type_meet(ciType* t1, ciType* t2) {
190 return type_meet_internal(t1, t2, outer());
191 }
192
193 // Accessors
194 ciTypeFlow* outer() const { return _outer; }
195
196 int stack_size() const { return _stack_size; }
197 void set_stack_size(int ss) { _stack_size = ss; }
198
199 int monitor_count() const { return _monitor_count; }
200 void set_monitor_count(int mc) { _monitor_count = mc; }
201
202 LocalSet* def_locals() { return &_def_locals; }
203 const LocalSet* def_locals() const { return &_def_locals; }
204
205 static Cell start_cell() { return (Cell)0; }
206 static Cell next_cell(Cell c) { return (Cell)(((int)c) + 1); }
207 Cell limit_cell() const {
208 return (Cell)(outer()->max_locals() + stack_size());
209 }
210
211 // Cell creation
212 Cell local(int lnum) const {
213 assert(lnum < outer()->max_locals(), "index check");
214 return (Cell)(lnum);
215 }
216
217 Cell stack(int snum) const {
218 assert(snum < stack_size(), "index check");
219 return (Cell)(outer()->max_locals() + snum);
220 }
221
222 Cell tos() const { return stack(stack_size()-1); }
223
224 // For external use only:
225 ciType* local_type_at(int i) const { return type_at(local(i)); }
226 ciType* stack_type_at(int i) const { return type_at(stack(i)); }
227
228 // Accessors for the type of some Cell c
229 ciType* type_at(Cell c) const {
230 assert(start_cell() <= c && c < limit_cell(), "out of bounds");
231 return _types[c];
232 }
233
234 void set_type_at(Cell c, ciType* type) {
235 assert(start_cell() <= c && c < limit_cell(), "out of bounds");
236 _types[c] = type;
237 }
238
239 // Top-of-stack operations.
240 void set_type_at_tos(ciType* type) { set_type_at(tos(), type); }
241 ciType* type_at_tos() const { return type_at(tos()); }
242
243 void push(ciType* type) {
244 _stack_size++;
245 set_type_at_tos(type);
246 }
247 void pop() {
248 debug_only(set_type_at_tos(bottom_type()));
249 _stack_size--;
250 }
251 ciType* pop_value() {
252 ciType* t = type_at_tos();
253 pop();
254 return t;
255 }
256
257 // Convenience operations.
258 bool is_reference(ciType* type) const {
259 return type == null_type() || !type->is_primitive_type();
260 }
261 bool is_int(ciType* type) const {
262 return type->basic_type() == T_INT;
263 }
264 bool is_long(ciType* type) const {
265 return type->basic_type() == T_LONG;
266 }
267 bool is_float(ciType* type) const {
268 return type->basic_type() == T_FLOAT;
269 }
270 bool is_double(ciType* type) const {
271 return type->basic_type() == T_DOUBLE;
272 }
273
274 void store_to_local(int lnum) {
275 _def_locals.add((uint) lnum);
276 }
277
278 void push_translate(ciType* type);
279
280 void push_int() {
281 push(ciType::make(T_INT));
282 }
283 void pop_int() {
284 assert(is_int(type_at_tos()), "must be integer");
285 pop();
286 }
287 void check_int(Cell c) {
288 assert(is_int(type_at(c)), "must be integer");
289 }
290 void push_double() {
291 push(ciType::make(T_DOUBLE));
292 push(double2_type());
293 }
294 void pop_double() {
295 assert(type_at_tos() == double2_type(), "must be 2nd half");
296 pop();
297 assert(is_double(type_at_tos()), "must be double");
298 pop();
299 }
300 void push_float() {
301 push(ciType::make(T_FLOAT));
302 }
303 void pop_float() {
304 assert(is_float(type_at_tos()), "must be float");
305 pop();
306 }
307 void push_long() {
308 push(ciType::make(T_LONG));
309 push(long2_type());
310 }
311 void pop_long() {
312 assert(type_at_tos() == long2_type(), "must be 2nd half");
313 pop();
314 assert(is_long(type_at_tos()), "must be long");
315 pop();
316 }
317 void push_object(ciKlass* klass) {
318 push(klass);
319 }
320 void pop_object() {
321 assert(is_reference(type_at_tos()), "must be reference type");
322 pop();
323 }
324 void pop_array() {
325 assert(type_at_tos() == null_type() ||
326 type_at_tos()->is_array_klass(), "must be array type");
327 pop();
328 }
329 // pop_objArray and pop_typeArray narrow the tos to ciObjArrayKlass
330 // or ciTypeArrayKlass (resp.). In the rare case that an explicit
331 // null is popped from the stack, we return NULL. Caller beware.
332 ciObjArrayKlass* pop_objArray() {
333 ciType* array = pop_value();
334 if (array == null_type()) return NULL;
335 assert(array->is_obj_array_klass(), "must be object array type");
336 return array->as_obj_array_klass();
337 }
338 ciTypeArrayKlass* pop_typeArray() {
339 ciType* array = pop_value();
340 if (array == null_type()) return NULL;
341 assert(array->is_type_array_klass(), "must be prim array type");
342 return array->as_type_array_klass();
343 }
344 void push_null() {
345 push(null_type());
346 }
347 void do_null_assert(ciKlass* unloaded_klass);
348
349 // Helper convenience routines.
350 void do_aaload(ciBytecodeStream* str);
351 void do_checkcast(ciBytecodeStream* str);
352 void do_getfield(ciBytecodeStream* str);
353 void do_getstatic(ciBytecodeStream* str);
354 void do_invoke(ciBytecodeStream* str, bool has_receiver);
355 void do_jsr(ciBytecodeStream* str);
356 void do_ldc(ciBytecodeStream* str);
357 void do_multianewarray(ciBytecodeStream* str);
358 void do_new(ciBytecodeStream* str);
359 void do_newarray(ciBytecodeStream* str);
360 void do_putfield(ciBytecodeStream* str);
361 void do_putstatic(ciBytecodeStream* str);
362 void do_ret(ciBytecodeStream* str);
363
364 void overwrite_local_double_long(int index) {
365 // Invalidate the previous local if it contains first half of
366 // a double or long value since it's seconf half is being overwritten.
367 int prev_index = index - 1;
368 if (prev_index >= 0 &&
369 (is_double(type_at(local(prev_index))) ||
370 is_long(type_at(local(prev_index))))) {
371 set_type_at(local(prev_index), bottom_type());
372 }
373 }
374
375 void load_local_object(int index) {
376 ciType* type = type_at(local(index));
377 assert(is_reference(type), "must be reference type");
378 push(type);
379 }
380 void store_local_object(int index) {
381 ciType* type = pop_value();
382 assert(is_reference(type) || type->is_return_address(),
383 "must be reference type or return address");
384 overwrite_local_double_long(index);
385 set_type_at(local(index), type);
386 store_to_local(index);
387 }
388
389 void load_local_double(int index) {
390 ciType* type = type_at(local(index));
391 ciType* type2 = type_at(local(index+1));
392 assert(is_double(type), "must be double type");
393 assert(type2 == double2_type(), "must be 2nd half");
394 push(type);
395 push(double2_type());
396 }
397 void store_local_double(int index) {
398 ciType* type2 = pop_value();
399 ciType* type = pop_value();
400 assert(is_double(type), "must be double");
401 assert(type2 == double2_type(), "must be 2nd half");
402 overwrite_local_double_long(index);
403 set_type_at(local(index), type);
404 set_type_at(local(index+1), type2);
405 store_to_local(index);
406 store_to_local(index+1);
407 }
408
409 void load_local_float(int index) {
410 ciType* type = type_at(local(index));
411 assert(is_float(type), "must be float type");
412 push(type);
413 }
414 void store_local_float(int index) {
415 ciType* type = pop_value();
416 assert(is_float(type), "must be float type");
417 overwrite_local_double_long(index);
418 set_type_at(local(index), type);
419 store_to_local(index);
420 }
421
422 void load_local_int(int index) {
423 ciType* type = type_at(local(index));
424 assert(is_int(type), "must be int type");
425 push(type);
426 }
427 void store_local_int(int index) {
428 ciType* type = pop_value();
429 assert(is_int(type), "must be int type");
430 overwrite_local_double_long(index);
431 set_type_at(local(index), type);
432 store_to_local(index);
433 }
434
435 void load_local_long(int index) {
436 ciType* type = type_at(local(index));
437 ciType* type2 = type_at(local(index+1));
438 assert(is_long(type), "must be long type");
439 assert(type2 == long2_type(), "must be 2nd half");
440 push(type);
441 push(long2_type());
442 }
443 void store_local_long(int index) {
444 ciType* type2 = pop_value();
445 ciType* type = pop_value();
446 assert(is_long(type), "must be long");
447 assert(type2 == long2_type(), "must be 2nd half");
448 overwrite_local_double_long(index);
449 set_type_at(local(index), type);
450 set_type_at(local(index+1), type2);
451 store_to_local(index);
452 store_to_local(index+1);
453 }
454
455 // Stop interpretation of this path with a trap.
456 void trap(ciBytecodeStream* str, ciKlass* klass, int index);
457
458 public:
459 StateVector(ciTypeFlow* outer);
460
461 // Copy our value into some other StateVector
462 void copy_into(StateVector* copy) const;
463
464 // Meets this StateVector with another, destructively modifying this
465 // one. Returns true if any modification takes place.
466 bool meet(const StateVector* incoming);
467
468 // Ditto, except that the incoming state is coming from an exception.
469 bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming);
470
471 // Apply the effect of one bytecode to this StateVector
472 bool apply_one_bytecode(ciBytecodeStream* stream);
473
474 // What is the bci of the trap?
475 int trap_bci() { return _trap_bci; }
476
477 // What is the index associated with the trap?
478 int trap_index() { return _trap_index; }
479
480 void print_cell_on(outputStream* st, Cell c) const PRODUCT_RETURN;
481 void print_on(outputStream* st) const PRODUCT_RETURN;
482 };
483
484 // Parameter for "find_block" calls:
485 // Describes the difference between a public and backedge copy.
486 enum CreateOption {
487 create_public_copy,
488 create_backedge_copy,
489 no_create
490 };
491
492 // Successor iterator
493 class SuccIter : public StackObj {
494 private:
495 Block* _pred;
496 int _index;
497 Block* _succ;
498 public:
499 SuccIter() : _pred(NULL), _index(-1), _succ(NULL) {}
500 SuccIter(Block* pred) : _pred(pred), _index(-1), _succ(NULL) { next(); }
501 int index() { return _index; }
502 Block* pred() { return _pred; } // Return predecessor
503 bool done() { return _index < 0; } // Finished?
504 Block* succ() { return _succ; } // Return current successor
505 void next(); // Advance
506 void set_succ(Block* succ); // Update current successor
507 bool is_normal_ctrl() { return index() < _pred->successors()->length(); }
508 };
509
510 // A basic block
511 class Block : public ResourceObj {
512 private:
513 ciBlock* _ciblock;
514 GrowableArray<Block*>* _exceptions;
515 GrowableArray<ciInstanceKlass*>* _exc_klasses;
516 GrowableArray<Block*>* _successors;
517 StateVector* _state;
518 JsrSet* _jsrs;
519
520 int _trap_bci;
521 int _trap_index;
522
523 // pre_order, assigned at first visit. Used as block ID and "visited" tag
524 int _pre_order;
525
526 // A post-order, used to compute the reverse post order (RPO) provided to the client
527 int _post_order; // used to compute rpo
528
529 // Has this block been cloned for a loop backedge?
530 bool _backedge_copy;
531
532 // A pointer used for our internal work list
533 Block* _next;
534 bool _on_work_list; // on the work list
535 Block* _rpo_next; // Reverse post order list
536
537 // Loop info
538 Loop* _loop; // nearest loop
539 bool _irreducible_entry; // entry to irreducible loop
540 bool _exception_entry; // entry to exception handler
541
542 ciBlock* ciblock() const { return _ciblock; }
543 StateVector* state() const { return _state; }
544
545 // Compute the exceptional successors and types for this Block.
546 void compute_exceptions();
547
548 public:
549 // constructors
550 Block(ciTypeFlow* outer, ciBlock* ciblk, JsrSet* jsrs);
551
552 void set_trap(int trap_bci, int trap_index) {
553 _trap_bci = trap_bci;
554 _trap_index = trap_index;
555 assert(has_trap(), "");
556 }
557 bool has_trap() const { return _trap_bci != -1; }
558 int trap_bci() const { assert(has_trap(), ""); return _trap_bci; }
559 int trap_index() const { assert(has_trap(), ""); return _trap_index; }
560
561 // accessors
562 ciTypeFlow* outer() const { return state()->outer(); }
563 int start() const { return _ciblock->start_bci(); }
564 int limit() const { return _ciblock->limit_bci(); }
565 int control() const { return _ciblock->control_bci(); }
566 JsrSet* jsrs() const { return _jsrs; }
567
568 bool is_backedge_copy() const { return _backedge_copy; }
569 void set_backedge_copy(bool z);
570 int backedge_copy_count() const { return outer()->backedge_copy_count(ciblock()->index(), _jsrs); }
571
572 // access to entry state
573 int stack_size() const { return _state->stack_size(); }
574 int monitor_count() const { return _state->monitor_count(); }
575 ciType* local_type_at(int i) const { return _state->local_type_at(i); }
576 ciType* stack_type_at(int i) const { return _state->stack_type_at(i); }
577
578 // Data flow on locals
579 bool is_invariant_local(uint v) const {
580 assert(is_loop_head(), "only loop heads");
581 // Find outermost loop with same loop head
582 Loop* lp = loop();
583 while (lp->parent() != NULL) {
584 if (lp->parent()->head() != lp->head()) break;
585 lp = lp->parent();
586 }
587 return !lp->def_locals()->test(v);
588 }
589 LocalSet* def_locals() { return _state->def_locals(); }
590 const LocalSet* def_locals() const { return _state->def_locals(); }
591
592 // Get the successors for this Block.
593 GrowableArray<Block*>* successors(ciBytecodeStream* str,
594 StateVector* state,
595 JsrSet* jsrs);
596 GrowableArray<Block*>* successors() {
597 assert(_successors != NULL, "must be filled in");
598 return _successors;
599 }
600
601 // Get the exceptional successors for this Block.
602 GrowableArray<Block*>* exceptions() {
603 if (_exceptions == NULL) {
604 compute_exceptions();
605 }
606 return _exceptions;
607 }
608
609 // Get the exception klasses corresponding to the
610 // exceptional successors for this Block.
611 GrowableArray<ciInstanceKlass*>* exc_klasses() {
612 if (_exc_klasses == NULL) {
613 compute_exceptions();
614 }
615 return _exc_klasses;
616 }
617
618 // Is this Block compatible with a given JsrSet?
619 bool is_compatible_with(JsrSet* other) {
620 return _jsrs->is_compatible_with(other);
621 }
622
623 // Copy the value of our state vector into another.
624 void copy_state_into(StateVector* copy) const {
625 _state->copy_into(copy);
626 }
627
628 // Copy the value of our JsrSet into another
629 void copy_jsrs_into(JsrSet* copy) const {
630 _jsrs->copy_into(copy);
631 }
632
633 // Meets the start state of this block with another state, destructively
634 // modifying this one. Returns true if any modification takes place.
635 bool meet(const StateVector* incoming) {
636 return state()->meet(incoming);
637 }
638
639 // Ditto, except that the incoming state is coming from an
640 // exception path. This means the stack is replaced by the
641 // appropriate exception type.
642 bool meet_exception(ciInstanceKlass* exc, const StateVector* incoming) {
643 return state()->meet_exception(exc, incoming);
644 }
645
646 // Work list manipulation
647 void set_next(Block* block) { _next = block; }
648 Block* next() const { return _next; }
649
650 void set_on_work_list(bool c) { _on_work_list = c; }
651 bool is_on_work_list() const { return _on_work_list; }
652
653 bool has_pre_order() const { return _pre_order >= 0; }
654 void set_pre_order(int po) { assert(!has_pre_order(), ""); _pre_order = po; }
655 int pre_order() const { assert(has_pre_order(), ""); return _pre_order; }
656 void set_next_pre_order() { set_pre_order(outer()->inc_next_pre_order()); }
657 bool is_start() const { return _pre_order == outer()->start_block_num(); }
658
659 // Reverse post order
660 void df_init();
661 bool has_post_order() const { return _post_order >= 0; }
662 void set_post_order(int po) { assert(!has_post_order() && po >= 0, ""); _post_order = po; }
663 void reset_post_order(int o){ _post_order = o; }
664 int post_order() const { assert(has_post_order(), ""); return _post_order; }
665
666 bool has_rpo() const { return has_post_order() && outer()->have_block_count(); }
667 int rpo() const { assert(has_rpo(), ""); return outer()->block_count() - post_order() - 1; }
668 void set_rpo_next(Block* b) { _rpo_next = b; }
669 Block* rpo_next() { return _rpo_next; }
670
671 // Loops
672 Loop* loop() const { return _loop; }
673 void set_loop(Loop* lp) { _loop = lp; }
674 bool is_loop_head() const { return _loop && _loop->head() == this; }
675 void set_irreducible_entry(bool c) { _irreducible_entry = c; }
676 bool is_irreducible_entry() const { return _irreducible_entry; }
677 bool is_visited() const { return has_pre_order(); }
678 bool is_post_visited() const { return has_post_order(); }
679 bool is_clonable_exit(Loop* lp);
680 Block* looping_succ(Loop* lp); // Successor inside of loop
681 bool is_single_entry_loop_head() const {
682 if (!is_loop_head()) return false;
683 for (Loop* lp = loop(); lp != NULL && lp->head() == this; lp = lp->parent())
684 if (lp->is_irreducible()) return false;
685 return true;
686 }
687
688 void print_value_on(outputStream* st) const PRODUCT_RETURN;
689 void print_on(outputStream* st) const PRODUCT_RETURN;
690 };
691
692 // Loop
693 class Loop : public ResourceObj {
694 private:
695 Loop* _parent;
696 Loop* _sibling; // List of siblings, null terminated
697 Loop* _child; // Head of child list threaded thru sibling pointer
698 Block* _head; // Head of loop
699 Block* _tail; // Tail of loop
700 bool _irreducible;
701 LocalSet _def_locals;
702
703 public:
704 Loop(Block* head, Block* tail) :
705 _head(head), _tail(tail),
706 _parent(NULL), _sibling(NULL), _child(NULL),
707 _irreducible(false), _def_locals() {}
708
709 Loop* parent() const { return _parent; }
710 Loop* sibling() const { return _sibling; }
711 Loop* child() const { return _child; }
712 Block* head() const { return _head; }
713 Block* tail() const { return _tail; }
714 void set_parent(Loop* p) { _parent = p; }
715 void set_sibling(Loop* s) { _sibling = s; }
716 void set_child(Loop* c) { _child = c; }
717 void set_head(Block* hd) { _head = hd; }
718 void set_tail(Block* tl) { _tail = tl; }
719
720 int depth() const; // nesting depth
721
722 // Returns true if lp is a nested loop or us.
723 bool contains(Loop* lp) const;
724 bool contains(Block* blk) const { return contains(blk->loop()); }
725
726 // Data flow on locals
727 LocalSet* def_locals() { return &_def_locals; }
728 const LocalSet* def_locals() const { return &_def_locals; }
729
730 // Merge the branch lp into this branch, sorting on the loop head
731 // pre_orders. Returns the new branch.
732 Loop* sorted_merge(Loop* lp);
733
734 // Mark non-single entry to loop
735 void set_irreducible(Block* entry) {
736 _irreducible = true;
737 entry->set_irreducible_entry(true);
738 }
739 bool is_irreducible() const { return _irreducible; }
740
741 bool is_root() const { return _tail->pre_order() == max_jint; }
742
743 void print(outputStream* st = tty, int indent = 0) const PRODUCT_RETURN;
744 };
745
746 // Postorder iteration over the loop tree.
747 class PostorderLoops : public StackObj {
748 private:
749 Loop* _root;
750 Loop* _current;
751 public:
752 PostorderLoops(Loop* root) : _root(root), _current(root) {
753 while (_current->child() != NULL) {
754 _current = _current->child();
755 }
756 }
757 bool done() { return _current == NULL; } // Finished iterating?
758 void next(); // Advance to next loop
759 Loop* current() { return _current; } // Return current loop.
760 };
761
762 // Preorder iteration over the loop tree.
763 class PreorderLoops : public StackObj {
764 private:
765 Loop* _root;
766 Loop* _current;
767 public:
768 PreorderLoops(Loop* root) : _root(root), _current(root) {}
769 bool done() { return _current == NULL; } // Finished iterating?
770 void next(); // Advance to next loop
771 Loop* current() { return _current; } // Return current loop.
772 };
773
774 // Standard indexes of successors, for various bytecodes.
775 enum {
776 FALL_THROUGH = 0, // normal control
777 IF_NOT_TAKEN = 0, // the not-taken branch of an if (i.e., fall-through)
778 IF_TAKEN = 1, // the taken branch of an if
779 GOTO_TARGET = 0, // unique successor for goto, jsr, or ret
780 SWITCH_DEFAULT = 0, // default branch of a switch
781 SWITCH_CASES = 1 // first index for any non-default switch branches
782 // Unlike in other blocks, the successors of a switch are listed uniquely.
783 };
784
785 private:
786 // A mapping from pre_order to Blocks. This array is created
787 // only at the end of the flow.
788 Block** _block_map;
789
790 // For each ciBlock index, a list of Blocks which share this ciBlock.
791 GrowableArray<Block*>** _idx_to_blocklist;
792 // count of ciBlocks
793 int _ciblock_count;
794
795 // Tells if a given instruction is able to generate an exception edge.
796 bool can_trap(ciBytecodeStream& str);
797
798 // Clone the loop heads. Returns true if any cloning occurred.
799 bool clone_loop_heads(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
800
801 // Clone lp's head and replace tail's successors with clone.
802 Block* clone_loop_head(Loop* lp, StateVector* temp_vector, JsrSet* temp_set);
803
804 public:
805 // Return the block beginning at bci which has a JsrSet compatible
806 // with jsrs.
807 Block* block_at(int bci, JsrSet* set, CreateOption option = create_public_copy);
808
809 // block factory
810 Block* get_block_for(int ciBlockIndex, JsrSet* jsrs, CreateOption option = create_public_copy);
811
812 // How many of the blocks have the backedge_copy bit set?
813 int backedge_copy_count(int ciBlockIndex, JsrSet* jsrs) const;
814
815 // Return an existing block containing bci which has a JsrSet compatible
816 // with jsrs, or NULL if there is none.
817 Block* existing_block_at(int bci, JsrSet* set) { return block_at(bci, set, no_create); }
818
819 // Tell whether the flow analysis has encountered an error of some sort.
820 bool failing() { return env()->failing() || _failure_reason != NULL; }
821
822 // Reason this compilation is failing, such as "too many basic blocks".
823 const char* failure_reason() { return _failure_reason; }
824
825 // Note a failure.
826 void record_failure(const char* reason);
827
828 // Return the block of a given pre-order number.
829 int have_block_count() const { return _block_map != NULL; }
830 int block_count() const { assert(have_block_count(), "");
831 return _next_pre_order; }
832 Block* pre_order_at(int po) const { assert(0 <= po && po < block_count(), "out of bounds");
833 return _block_map[po]; }
834 Block* start_block() const { return pre_order_at(start_block_num()); }
835 int start_block_num() const { return 0; }
836 Block* rpo_at(int rpo) const { assert(0 <= rpo && rpo < block_count(), "out of bounds");
837 return _block_map[rpo]; }
838 int next_pre_order() { return _next_pre_order; }
839 int inc_next_pre_order() { return _next_pre_order++; }
840
841 private:
842 // A work list used during flow analysis.
843 Block* _work_list;
844
845 // List of blocks in reverse post order
846 Block* _rpo_list;
847
848 // Next Block::_pre_order. After mapping, doubles as block_count.
849 int _next_pre_order;
850
851 // Are there more blocks on the work list?
852 bool work_list_empty() { return _work_list == NULL; }
853
854 // Get the next basic block from our work list.
855 Block* work_list_next();
856
857 // Add a basic block to our work list.
858 void add_to_work_list(Block* block);
859
860 // Prepend a basic block to rpo list.
861 void prepend_to_rpo_list(Block* blk) {
862 blk->set_rpo_next(_rpo_list);
863 _rpo_list = blk;
864 }
865
866 // Root of the loop tree
867 Loop* _loop_tree_root;
868
869 // State used for make_jsr_record
870 int _jsr_count;
871 GrowableArray<JsrRecord*>* _jsr_records;
872
873 public:
874 // Make a JsrRecord for a given (entry, return) pair, if such a record
875 // does not already exist.
876 JsrRecord* make_jsr_record(int entry_address, int return_address);
877
878 void set_loop_tree_root(Loop* ltr) { _loop_tree_root = ltr; }
879 Loop* loop_tree_root() { return _loop_tree_root; }
880
881 private:
882 // Get the initial state for start_bci:
883 const StateVector* get_start_state();
884
885 // Merge the current state into all exceptional successors at the
886 // current point in the code.
887 void flow_exceptions(GrowableArray<Block*>* exceptions,
888 GrowableArray<ciInstanceKlass*>* exc_klasses,
889 StateVector* state);
890
891 // Merge the current state into all successors at the current point
892 // in the code.
893 void flow_successors(GrowableArray<Block*>* successors,
894 StateVector* state);
895
896 // Interpret the effects of the bytecodes on the incoming state
897 // vector of a basic block. Push the changed state to succeeding
898 // basic blocks.
899 void flow_block(Block* block,
900 StateVector* scratch_state,
901 JsrSet* scratch_jsrs);
902
903 // Perform the type flow analysis, creating and cloning Blocks as
904 // necessary.
905 void flow_types();
906
907 // Perform the depth first type flow analysis. Helper for flow_types.
908 void df_flow_types(Block* start,
909 bool do_flow,
910 StateVector* temp_vector,
911 JsrSet* temp_set);
912
913 // Incrementally build loop tree.
914 void build_loop_tree(Block* blk);
915
916 // Create the block map, which indexes blocks in pre_order.
917 void map_blocks();
918
919 public:
920 // Perform type inference flow analysis.
921 void do_flow();
922
923 void print_on(outputStream* st) const PRODUCT_RETURN;
924
925 void rpo_print_on(outputStream* st) const PRODUCT_RETURN;
926 };