1 /*
2 * Copyright (c) 1997, 2016, 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
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "interpreter/bytecodeStream.hpp"
27 #include "logging/log.hpp"
28 #include "oops/generateOopMap.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "oops/symbol.hpp"
31 #include "runtime/handles.inline.hpp"
32 #include "runtime/java.hpp"
33 #include "runtime/relocator.hpp"
34 #include "runtime/timerTrace.hpp"
35 #include "utilities/bitMap.inline.hpp"
36 #include "utilities/ostream.hpp"
37 #include "prims/methodHandles.hpp"
38
39 //
40 //
41 // Compute stack layouts for each instruction in method.
42 //
43 // Problems:
44 // - What to do about jsr with different types of local vars?
45 // Need maps that are conditional on jsr path?
46 // - Jsr and exceptions should be done more efficiently (the retAddr stuff)
47 //
48 // Alternative:
49 // - Could extend verifier to provide this information.
50 // For: one fewer abstract interpreter to maintain. Against: the verifier
51 // solves a bigger problem so slower (undesirable to force verification of
52 // everything?).
53 //
54 // Algorithm:
55 // Partition bytecodes into basic blocks
56 // For each basic block: store entry state (vars, stack). For instructions
57 // inside basic blocks we do not store any state (instead we recompute it
58 // from state produced by previous instruction).
59 //
60 // Perform abstract interpretation of bytecodes over this lattice:
61 //
62 // _--'#'--_
63 // / / \ \
64 // / / \ \
65 // / | | \
66 // 'r' 'v' 'p' ' '
67 // \ | | /
68 // \ \ / /
69 // \ \ / /
70 // -- '@' --
71 //
72 // '#' top, result of conflict merge
73 // 'r' reference type
74 // 'v' value type
75 // 'p' pc type for jsr/ret
76 // ' ' uninitialized; never occurs on operand stack in Java
77 // '@' bottom/unexecuted; initial state each bytecode.
78 //
79 // Basic block headers are the only merge points. We use this iteration to
80 // compute the information:
81 //
82 // find basic blocks;
83 // initialize them with uninitialized state;
84 // initialize first BB according to method signature;
85 // mark first BB changed
86 // while (some BB is changed) do {
87 // perform abstract interpration of all bytecodes in BB;
88 // merge exit state of BB into entry state of all successor BBs,
89 // noting if any of these change;
90 // }
91 //
92 // One additional complication is necessary. The jsr instruction pushes
93 // a return PC on the stack (a 'p' type in the abstract interpretation).
94 // To be able to process "ret" bytecodes, we keep track of these return
95 // PC's in a 'retAddrs' structure in abstract interpreter context (when
96 // processing a "ret" bytecodes, it is not sufficient to know that it gets
97 // an argument of the right type 'p'; we need to know which address it
98 // returns to).
99 //
100 // (Note this comment is borrowed form the original author of the algorithm)
101
102 // ComputeCallStack
103 //
104 // Specialization of SignatureIterator - compute the effects of a call
105 //
106 class ComputeCallStack : public SignatureIterator {
107 CellTypeState *_effect;
108 int _idx;
109
110 void setup();
111 void set(CellTypeState state) { _effect[_idx++] = state; }
112 int length() { return _idx; };
113
114 virtual void do_bool () { set(CellTypeState::value); };
115 virtual void do_char () { set(CellTypeState::value); };
116 virtual void do_float () { set(CellTypeState::value); };
117 virtual void do_byte () { set(CellTypeState::value); };
118 virtual void do_short () { set(CellTypeState::value); };
119 virtual void do_int () { set(CellTypeState::value); };
120 virtual void do_void () { set(CellTypeState::bottom);};
121 virtual void do_object(int begin, int end) { set(CellTypeState::ref); };
122 virtual void do_array (int begin, int end) { set(CellTypeState::ref); };
123
124 void do_double() { set(CellTypeState::value);
125 set(CellTypeState::value); }
126 void do_long () { set(CellTypeState::value);
127 set(CellTypeState::value); }
128
129 public:
130 ComputeCallStack(Symbol* signature) : SignatureIterator(signature) {};
131
132 // Compute methods
133 int compute_for_parameters(bool is_static, CellTypeState *effect) {
134 _idx = 0;
135 _effect = effect;
136
137 if (!is_static)
138 effect[_idx++] = CellTypeState::ref;
139
140 iterate_parameters();
141
142 return length();
143 };
144
145 int compute_for_returntype(CellTypeState *effect) {
146 _idx = 0;
147 _effect = effect;
148 iterate_returntype();
149 set(CellTypeState::bottom); // Always terminate with a bottom state, so ppush works
150
151 return length();
152 }
153 };
154
155 //=========================================================================================
156 // ComputeEntryStack
157 //
158 // Specialization of SignatureIterator - in order to set up first stack frame
159 //
160 class ComputeEntryStack : public SignatureIterator {
161 CellTypeState *_effect;
162 int _idx;
163
164 void setup();
165 void set(CellTypeState state) { _effect[_idx++] = state; }
166 int length() { return _idx; };
167
168 virtual void do_bool () { set(CellTypeState::value); };
169 virtual void do_char () { set(CellTypeState::value); };
170 virtual void do_float () { set(CellTypeState::value); };
171 virtual void do_byte () { set(CellTypeState::value); };
172 virtual void do_short () { set(CellTypeState::value); };
173 virtual void do_int () { set(CellTypeState::value); };
174 virtual void do_void () { set(CellTypeState::bottom);};
175 virtual void do_object(int begin, int end) { set(CellTypeState::make_slot_ref(_idx)); }
176 virtual void do_array (int begin, int end) { set(CellTypeState::make_slot_ref(_idx)); }
177
178 void do_double() { set(CellTypeState::value);
179 set(CellTypeState::value); }
180 void do_long () { set(CellTypeState::value);
181 set(CellTypeState::value); }
182
183 public:
184 ComputeEntryStack(Symbol* signature) : SignatureIterator(signature) {};
185
186 // Compute methods
187 int compute_for_parameters(bool is_static, CellTypeState *effect) {
188 _idx = 0;
189 _effect = effect;
190
191 if (!is_static)
192 effect[_idx++] = CellTypeState::make_slot_ref(0);
193
194 iterate_parameters();
195
196 return length();
197 };
198
199 int compute_for_returntype(CellTypeState *effect) {
200 _idx = 0;
201 _effect = effect;
202 iterate_returntype();
203 set(CellTypeState::bottom); // Always terminate with a bottom state, so ppush works
204
205 return length();
206 }
207 };
208
209 //=====================================================================================
210 //
211 // Implementation of RetTable/RetTableEntry
212 //
213 // Contains function to itereate through all bytecodes
214 // and find all return entry points
215 //
216 int RetTable::_init_nof_entries = 10;
217 int RetTableEntry::_init_nof_jsrs = 5;
218
219 void RetTableEntry::add_delta(int bci, int delta) {
220 if (_target_bci > bci) _target_bci += delta;
221
222 for (int k = 0; k < _jsrs->length(); k++) {
223 int jsr = _jsrs->at(k);
224 if (jsr > bci) _jsrs->at_put(k, jsr+delta);
225 }
226 }
227
228 void RetTable::compute_ret_table(const methodHandle& method) {
229 BytecodeStream i(method);
230 Bytecodes::Code bytecode;
231
232 while( (bytecode = i.next()) >= 0) {
233 switch (bytecode) {
234 case Bytecodes::_jsr:
235 add_jsr(i.next_bci(), i.dest());
236 break;
237 case Bytecodes::_jsr_w:
238 add_jsr(i.next_bci(), i.dest_w());
239 break;
240 }
241 }
242 }
243
244 void RetTable::add_jsr(int return_bci, int target_bci) {
245 RetTableEntry* entry = _first;
246
247 // Scan table for entry
248 for (;entry && entry->target_bci() != target_bci; entry = entry->next());
249
250 if (!entry) {
251 // Allocate new entry and put in list
252 entry = new RetTableEntry(target_bci, _first);
253 _first = entry;
254 }
255
256 // Now "entry" is set. Make sure that the entry is initialized
257 // and has room for the new jsr.
258 entry->add_jsr(return_bci);
259 }
260
261 RetTableEntry* RetTable::find_jsrs_for_target(int targBci) {
262 RetTableEntry *cur = _first;
263
264 while(cur) {
265 assert(cur->target_bci() != -1, "sanity check");
266 if (cur->target_bci() == targBci) return cur;
267 cur = cur->next();
268 }
269 ShouldNotReachHere();
270 return NULL;
271 }
272
273 // The instruction at bci is changing size by "delta". Update the return map.
274 void RetTable::update_ret_table(int bci, int delta) {
275 RetTableEntry *cur = _first;
276 while(cur) {
277 cur->add_delta(bci, delta);
278 cur = cur->next();
279 }
280 }
281
282 //
283 // Celltype state
284 //
285
286 CellTypeState CellTypeState::bottom = CellTypeState::make_bottom();
287 CellTypeState CellTypeState::uninit = CellTypeState::make_any(uninit_value);
288 CellTypeState CellTypeState::ref = CellTypeState::make_any(ref_conflict);
289 CellTypeState CellTypeState::value = CellTypeState::make_any(val_value);
290 CellTypeState CellTypeState::refUninit = CellTypeState::make_any(ref_conflict | uninit_value);
291 CellTypeState CellTypeState::top = CellTypeState::make_top();
292 CellTypeState CellTypeState::addr = CellTypeState::make_any(addr_conflict);
293
294 // Commonly used constants
295 static CellTypeState epsilonCTS[1] = { CellTypeState::bottom };
296 static CellTypeState refCTS = CellTypeState::ref;
297 static CellTypeState valCTS = CellTypeState::value;
298 static CellTypeState vCTS[2] = { CellTypeState::value, CellTypeState::bottom };
299 static CellTypeState rCTS[2] = { CellTypeState::ref, CellTypeState::bottom };
300 static CellTypeState rrCTS[3] = { CellTypeState::ref, CellTypeState::ref, CellTypeState::bottom };
301 static CellTypeState vrCTS[3] = { CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
302 static CellTypeState vvCTS[3] = { CellTypeState::value, CellTypeState::value, CellTypeState::bottom };
303 static CellTypeState rvrCTS[4] = { CellTypeState::ref, CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
304 static CellTypeState vvrCTS[4] = { CellTypeState::value, CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
305 static CellTypeState vvvCTS[4] = { CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::bottom };
306 static CellTypeState vvvrCTS[5] = { CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
307 static CellTypeState vvvvCTS[5] = { CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::bottom };
308
309 char CellTypeState::to_char() const {
310 if (can_be_reference()) {
311 if (can_be_value() || can_be_address())
312 return '#'; // Conflict that needs to be rewritten
313 else
314 return 'r';
315 } else if (can_be_value())
316 return 'v';
317 else if (can_be_address())
318 return 'p';
319 else if (can_be_uninit())
320 return ' ';
321 else
322 return '@';
323 }
324
325
326 // Print a detailed CellTypeState. Indicate all bits that are set. If
327 // the CellTypeState represents an address or a reference, print the
328 // value of the additional information.
329 void CellTypeState::print(outputStream *os) {
330 if (can_be_address()) {
331 os->print("(p");
332 } else {
333 os->print("( ");
334 }
335 if (can_be_reference()) {
336 os->print("r");
337 } else {
338 os->print(" ");
339 }
340 if (can_be_value()) {
341 os->print("v");
342 } else {
343 os->print(" ");
344 }
345 if (can_be_uninit()) {
346 os->print("u|");
347 } else {
348 os->print(" |");
349 }
350 if (is_info_top()) {
351 os->print("Top)");
352 } else if (is_info_bottom()) {
353 os->print("Bot)");
354 } else {
355 if (is_reference()) {
356 int info = get_info();
357 int data = info & ~(ref_not_lock_bit | ref_slot_bit);
358 if (info & ref_not_lock_bit) {
359 // Not a monitor lock reference.
360 if (info & ref_slot_bit) {
361 // slot
362 os->print("slot%d)", data);
363 } else {
364 // line
365 os->print("line%d)", data);
366 }
367 } else {
368 // lock
369 os->print("lock%d)", data);
370 }
371 } else {
372 os->print("%d)", get_info());
373 }
374 }
375 }
376
377 //
378 // Basicblock handling methods
379 //
380
381 void GenerateOopMap::initialize_bb() {
382 _gc_points = 0;
383 _bb_count = 0;
384 _bb_hdr_bits.reinitialize(method()->code_size());
385 }
386
387 void GenerateOopMap::bb_mark_fct(GenerateOopMap *c, int bci, int *data) {
388 assert(bci>= 0 && bci < c->method()->code_size(), "index out of bounds");
389 if (c->is_bb_header(bci))
390 return;
391
392 if (TraceNewOopMapGeneration) {
393 tty->print_cr("Basicblock#%d begins at: %d", c->_bb_count, bci);
394 }
395 c->set_bbmark_bit(bci);
396 c->_bb_count++;
397 }
398
399
400 void GenerateOopMap::mark_bbheaders_and_count_gc_points() {
401 initialize_bb();
402
403 bool fellThrough = false; // False to get first BB marked.
404
405 // First mark all exception handlers as start of a basic-block
406 ExceptionTable excps(method());
407 for(int i = 0; i < excps.length(); i ++) {
408 bb_mark_fct(this, excps.handler_pc(i), NULL);
409 }
410
411 // Then iterate through the code
412 BytecodeStream bcs(_method);
413 Bytecodes::Code bytecode;
414
415 while( (bytecode = bcs.next()) >= 0) {
416 int bci = bcs.bci();
417
418 if (!fellThrough)
419 bb_mark_fct(this, bci, NULL);
420
421 fellThrough = jump_targets_do(&bcs, &GenerateOopMap::bb_mark_fct, NULL);
422
423 /* We will also mark successors of jsr's as basic block headers. */
424 switch (bytecode) {
425 case Bytecodes::_jsr:
426 assert(!fellThrough, "should not happen");
427 bb_mark_fct(this, bci + Bytecodes::length_for(bytecode), NULL);
428 break;
429 case Bytecodes::_jsr_w:
430 assert(!fellThrough, "should not happen");
431 bb_mark_fct(this, bci + Bytecodes::length_for(bytecode), NULL);
432 break;
433 }
434
435 if (possible_gc_point(&bcs))
436 _gc_points++;
437 }
438 }
439
440 void GenerateOopMap::reachable_basicblock(GenerateOopMap *c, int bci, int *data) {
441 assert(bci>= 0 && bci < c->method()->code_size(), "index out of bounds");
442 BasicBlock* bb = c->get_basic_block_at(bci);
443 if (bb->is_dead()) {
444 bb->mark_as_alive();
445 *data = 1; // Mark basicblock as changed
446 }
447 }
448
449
450 void GenerateOopMap::mark_reachable_code() {
451 int change = 1; // int to get function pointers to work
452
453 // Mark entry basic block as alive and all exception handlers
454 _basic_blocks[0].mark_as_alive();
455 ExceptionTable excps(method());
456 for(int i = 0; i < excps.length(); i++) {
457 BasicBlock *bb = get_basic_block_at(excps.handler_pc(i));
458 // If block is not already alive (due to multiple exception handlers to same bb), then
459 // make it alive
460 if (bb->is_dead()) bb->mark_as_alive();
461 }
462
463 BytecodeStream bcs(_method);
464
465 // Iterate through all basic blocks until we reach a fixpoint
466 while (change) {
467 change = 0;
468
469 for (int i = 0; i < _bb_count; i++) {
470 BasicBlock *bb = &_basic_blocks[i];
471 if (bb->is_alive()) {
472 // Position bytecodestream at last bytecode in basicblock
473 bcs.set_start(bb->_end_bci);
474 bcs.next();
475 Bytecodes::Code bytecode = bcs.code();
476 int bci = bcs.bci();
477 assert(bci == bb->_end_bci, "wrong bci");
478
479 bool fell_through = jump_targets_do(&bcs, &GenerateOopMap::reachable_basicblock, &change);
480
481 // We will also mark successors of jsr's as alive.
482 switch (bytecode) {
483 case Bytecodes::_jsr:
484 case Bytecodes::_jsr_w:
485 assert(!fell_through, "should not happen");
486 reachable_basicblock(this, bci + Bytecodes::length_for(bytecode), &change);
487 break;
488 }
489 if (fell_through) {
490 // Mark successor as alive
491 if (bb[1].is_dead()) {
492 bb[1].mark_as_alive();
493 change = 1;
494 }
495 }
496 }
497 }
498 }
499 }
500
501 /* If the current instruction in "c" has no effect on control flow,
502 returns "true". Otherwise, calls "jmpFct" one or more times, with
503 "c", an appropriate "pcDelta", and "data" as arguments, then
504 returns "false". There is one exception: if the current
505 instruction is a "ret", returns "false" without calling "jmpFct".
506 Arrangements for tracking the control flow of a "ret" must be made
507 externally. */
508 bool GenerateOopMap::jump_targets_do(BytecodeStream *bcs, jmpFct_t jmpFct, int *data) {
509 int bci = bcs->bci();
510
511 switch (bcs->code()) {
512 case Bytecodes::_ifeq:
513 case Bytecodes::_ifne:
514 case Bytecodes::_iflt:
515 case Bytecodes::_ifge:
516 case Bytecodes::_ifgt:
517 case Bytecodes::_ifle:
518 case Bytecodes::_if_icmpeq:
519 case Bytecodes::_if_icmpne:
520 case Bytecodes::_if_icmplt:
521 case Bytecodes::_if_icmpge:
522 case Bytecodes::_if_icmpgt:
523 case Bytecodes::_if_icmple:
524 case Bytecodes::_if_acmpeq:
525 case Bytecodes::_if_acmpne:
526 case Bytecodes::_ifnull:
527 case Bytecodes::_ifnonnull:
528 (*jmpFct)(this, bcs->dest(), data);
529 (*jmpFct)(this, bci + 3, data);
530 break;
531
532 case Bytecodes::_goto:
533 (*jmpFct)(this, bcs->dest(), data);
534 break;
535 case Bytecodes::_goto_w:
536 (*jmpFct)(this, bcs->dest_w(), data);
537 break;
538 case Bytecodes::_tableswitch:
539 { Bytecode_tableswitch tableswitch(method(), bcs->bcp());
540 int len = tableswitch.length();
541
542 (*jmpFct)(this, bci + tableswitch.default_offset(), data); /* Default. jump address */
543 while (--len >= 0) {
544 (*jmpFct)(this, bci + tableswitch.dest_offset_at(len), data);
545 }
546 break;
547 }
548
549 case Bytecodes::_lookupswitch:
550 { Bytecode_lookupswitch lookupswitch(method(), bcs->bcp());
551 int npairs = lookupswitch.number_of_pairs();
552 (*jmpFct)(this, bci + lookupswitch.default_offset(), data); /* Default. */
553 while(--npairs >= 0) {
554 LookupswitchPair pair = lookupswitch.pair_at(npairs);
555 (*jmpFct)(this, bci + pair.offset(), data);
556 }
557 break;
558 }
559 case Bytecodes::_jsr:
560 assert(bcs->is_wide()==false, "sanity check");
561 (*jmpFct)(this, bcs->dest(), data);
562
563
564
565 break;
566 case Bytecodes::_jsr_w:
567 (*jmpFct)(this, bcs->dest_w(), data);
568 break;
569 case Bytecodes::_wide:
570 ShouldNotReachHere();
571 return true;
572 break;
573 case Bytecodes::_athrow:
574 case Bytecodes::_ireturn:
575 case Bytecodes::_lreturn:
576 case Bytecodes::_freturn:
577 case Bytecodes::_dreturn:
578 case Bytecodes::_areturn:
579 case Bytecodes::_return:
580 case Bytecodes::_ret:
581 break;
582 default:
583 return true;
584 }
585 return false;
586 }
587
588 /* Requires "pc" to be the head of a basic block; returns that basic
589 block. */
590 BasicBlock *GenerateOopMap::get_basic_block_at(int bci) const {
591 BasicBlock* bb = get_basic_block_containing(bci);
592 assert(bb->_bci == bci, "should have found BB");
593 return bb;
594 }
595
596 // Requires "pc" to be the start of an instruction; returns the basic
597 // block containing that instruction. */
598 BasicBlock *GenerateOopMap::get_basic_block_containing(int bci) const {
599 BasicBlock *bbs = _basic_blocks;
600 int lo = 0, hi = _bb_count - 1;
601
602 while (lo <= hi) {
603 int m = (lo + hi) / 2;
604 int mbci = bbs[m]._bci;
605 int nbci;
606
607 if ( m == _bb_count-1) {
608 assert( bci >= mbci && bci < method()->code_size(), "sanity check failed");
609 return bbs+m;
610 } else {
611 nbci = bbs[m+1]._bci;
612 }
613
614 if ( mbci <= bci && bci < nbci) {
615 return bbs+m;
616 } else if (mbci < bci) {
617 lo = m + 1;
618 } else {
619 assert(mbci > bci, "sanity check");
620 hi = m - 1;
621 }
622 }
623
624 fatal("should have found BB");
625 return NULL;
626 }
627
628 void GenerateOopMap::restore_state(BasicBlock *bb)
629 {
630 memcpy(_state, bb->_state, _state_len*sizeof(CellTypeState));
631 _stack_top = bb->_stack_top;
632 _monitor_top = bb->_monitor_top;
633 }
634
635 int GenerateOopMap::next_bb_start_pc(BasicBlock *bb) {
636 int bbNum = bb - _basic_blocks + 1;
637 if (bbNum == _bb_count)
638 return method()->code_size();
639
640 return _basic_blocks[bbNum]._bci;
641 }
642
643 //
644 // CellType handling methods
645 //
646
647 // Allocate memory and throw LinkageError if failure.
648 #define ALLOC_RESOURCE_ARRAY(var, type, count) \
649 var = NEW_RESOURCE_ARRAY_RETURN_NULL(type, count); \
650 if (var == NULL) { \
651 report_error("Cannot reserve enough memory to analyze this method"); \
652 return; \
653 }
654
655
656 void GenerateOopMap::init_state() {
657 _state_len = _max_locals + _max_stack + _max_monitors;
658 ALLOC_RESOURCE_ARRAY(_state, CellTypeState, _state_len);
659 memset(_state, 0, _state_len * sizeof(CellTypeState));
660 int count = MAX3(_max_locals, _max_stack, _max_monitors) + 1/*for null terminator char */;
661 ALLOC_RESOURCE_ARRAY(_state_vec_buf, char, count);
662 }
663
664 void GenerateOopMap::make_context_uninitialized() {
665 CellTypeState* vs = vars();
666
667 for (int i = 0; i < _max_locals; i++)
668 vs[i] = CellTypeState::uninit;
669
670 _stack_top = 0;
671 _monitor_top = 0;
672 }
673
674 int GenerateOopMap::methodsig_to_effect(Symbol* signature, bool is_static, CellTypeState* effect) {
675 ComputeEntryStack ces(signature);
676 return ces.compute_for_parameters(is_static, effect);
677 }
678
679 // Return result of merging cts1 and cts2.
680 CellTypeState CellTypeState::merge(CellTypeState cts, int slot) const {
681 CellTypeState result;
682
683 assert(!is_bottom() && !cts.is_bottom(),
684 "merge of bottom values is handled elsewhere");
685
686 result._state = _state | cts._state;
687
688 // If the top bit is set, we don't need to do any more work.
689 if (!result.is_info_top()) {
690 assert((result.can_be_address() || result.can_be_reference()),
691 "only addresses and references have non-top info");
692
693 if (!equal(cts)) {
694 // The two values being merged are different. Raise to top.
695 if (result.is_reference()) {
696 result = CellTypeState::make_slot_ref(slot);
697 } else {
698 result._state |= info_conflict;
699 }
700 }
701 }
702 assert(result.is_valid_state(), "checking that CTS merge maintains legal state");
703
704 return result;
705 }
706
707 // Merge the variable state for locals and stack from cts into bbts.
708 bool GenerateOopMap::merge_local_state_vectors(CellTypeState* cts,
709 CellTypeState* bbts) {
710 int i;
711 int len = _max_locals + _stack_top;
712 bool change = false;
713
714 for (i = len - 1; i >= 0; i--) {
715 CellTypeState v = cts[i].merge(bbts[i], i);
716 change = change || !v.equal(bbts[i]);
717 bbts[i] = v;
718 }
719
720 return change;
721 }
722
723 // Merge the monitor stack state from cts into bbts.
724 bool GenerateOopMap::merge_monitor_state_vectors(CellTypeState* cts,
725 CellTypeState* bbts) {
726 bool change = false;
727 if (_max_monitors > 0 && _monitor_top != bad_monitors) {
728 // If there are no monitors in the program, or there has been
729 // a monitor matching error before this point in the program,
730 // then we do not merge in the monitor state.
731
732 int base = _max_locals + _max_stack;
733 int len = base + _monitor_top;
734 for (int i = len - 1; i >= base; i--) {
735 CellTypeState v = cts[i].merge(bbts[i], i);
736
737 // Can we prove that, when there has been a change, it will already
738 // have been detected at this point? That would make this equal
739 // check here unnecessary.
740 change = change || !v.equal(bbts[i]);
741 bbts[i] = v;
742 }
743 }
744
745 return change;
746 }
747
748 void GenerateOopMap::copy_state(CellTypeState *dst, CellTypeState *src) {
749 int len = _max_locals + _stack_top;
750 for (int i = 0; i < len; i++) {
751 if (src[i].is_nonlock_reference()) {
752 dst[i] = CellTypeState::make_slot_ref(i);
753 } else {
754 dst[i] = src[i];
755 }
756 }
757 if (_max_monitors > 0 && _monitor_top != bad_monitors) {
758 int base = _max_locals + _max_stack;
759 len = base + _monitor_top;
760 for (int i = base; i < len; i++) {
761 dst[i] = src[i];
762 }
763 }
764 }
765
766
767 // Merge the states for the current block and the next. As long as a
768 // block is reachable the locals and stack must be merged. If the
769 // stack heights don't match then this is a verification error and
770 // it's impossible to interpret the code. Simultaneously monitor
771 // states are being check to see if they nest statically. If monitor
772 // depths match up then their states are merged. Otherwise the
773 // mismatch is simply recorded and interpretation continues since
774 // monitor matching is purely informational and doesn't say anything
775 // about the correctness of the code.
776 void GenerateOopMap::merge_state_into_bb(BasicBlock *bb) {
777 guarantee(bb != NULL, "null basicblock");
778 assert(bb->is_alive(), "merging state into a dead basicblock");
779
780 if (_stack_top == bb->_stack_top) {
781 // always merge local state even if monitors don't match.
782 if (merge_local_state_vectors(_state, bb->_state)) {
783 bb->set_changed(true);
784 }
785 if (_monitor_top == bb->_monitor_top) {
786 // monitors still match so continue merging monitor states.
787 if (merge_monitor_state_vectors(_state, bb->_state)) {
788 bb->set_changed(true);
789 }
790 } else {
791 if (log_is_enabled(Info, monitormismatch)) {
792 report_monitor_mismatch("monitor stack height merge conflict");
793 }
794 // When the monitor stacks are not matched, we set _monitor_top to
795 // bad_monitors. This signals that, from here on, the monitor stack cannot
796 // be trusted. In particular, monitorexit bytecodes may throw
797 // exceptions. We mark this block as changed so that the change
798 // propagates properly.
799 bb->_monitor_top = bad_monitors;
800 bb->set_changed(true);
801 _monitor_safe = false;
802 }
803 } else if (!bb->is_reachable()) {
804 // First time we look at this BB
805 copy_state(bb->_state, _state);
806 bb->_stack_top = _stack_top;
807 bb->_monitor_top = _monitor_top;
808 bb->set_changed(true);
809 } else {
810 verify_error("stack height conflict: %d vs. %d", _stack_top, bb->_stack_top);
811 }
812 }
813
814 void GenerateOopMap::merge_state(GenerateOopMap *gom, int bci, int* data) {
815 gom->merge_state_into_bb(gom->get_basic_block_at(bci));
816 }
817
818 void GenerateOopMap::set_var(int localNo, CellTypeState cts) {
819 assert(cts.is_reference() || cts.is_value() || cts.is_address(),
820 "wrong celltypestate");
821 if (localNo < 0 || localNo > _max_locals) {
822 verify_error("variable write error: r%d", localNo);
823 return;
824 }
825 vars()[localNo] = cts;
826 }
827
828 CellTypeState GenerateOopMap::get_var(int localNo) {
829 assert(localNo < _max_locals + _nof_refval_conflicts, "variable read error");
830 if (localNo < 0 || localNo > _max_locals) {
831 verify_error("variable read error: r%d", localNo);
832 return valCTS; // just to pick something;
833 }
834 return vars()[localNo];
835 }
836
837 CellTypeState GenerateOopMap::pop() {
838 if ( _stack_top <= 0) {
839 verify_error("stack underflow");
840 return valCTS; // just to pick something
841 }
842 return stack()[--_stack_top];
843 }
844
845 void GenerateOopMap::push(CellTypeState cts) {
846 if ( _stack_top >= _max_stack) {
847 verify_error("stack overflow");
848 return;
849 }
850 stack()[_stack_top++] = cts;
851 }
852
853 CellTypeState GenerateOopMap::monitor_pop() {
854 assert(_monitor_top != bad_monitors, "monitor_pop called on error monitor stack");
855 if (_monitor_top == 0) {
856 // We have detected a pop of an empty monitor stack.
857 _monitor_safe = false;
858 _monitor_top = bad_monitors;
859
860 if (log_is_enabled(Info, monitormismatch)) {
861 report_monitor_mismatch("monitor stack underflow");
862 }
863 return CellTypeState::ref; // just to keep the analysis going.
864 }
865 return monitors()[--_monitor_top];
866 }
867
868 void GenerateOopMap::monitor_push(CellTypeState cts) {
869 assert(_monitor_top != bad_monitors, "monitor_push called on error monitor stack");
870 if (_monitor_top >= _max_monitors) {
871 // Some monitorenter is being executed more than once.
872 // This means that the monitor stack cannot be simulated.
873 _monitor_safe = false;
874 _monitor_top = bad_monitors;
875
876 if (log_is_enabled(Info, monitormismatch)) {
877 report_monitor_mismatch("monitor stack overflow");
878 }
879 return;
880 }
881 monitors()[_monitor_top++] = cts;
882 }
883
884 //
885 // Interpretation handling methods
886 //
887
888 void GenerateOopMap::do_interpretation()
889 {
890 // "i" is just for debugging, so we can detect cases where this loop is
891 // iterated more than once.
892 int i = 0;
893 do {
894 #ifndef PRODUCT
895 if (TraceNewOopMapGeneration) {
896 tty->print("\n\nIteration #%d of do_interpretation loop, method:\n", i);
897 method()->print_name(tty);
898 tty->print("\n\n");
899 }
900 #endif
901 _conflict = false;
902 _monitor_safe = true;
903 // init_state is now called from init_basic_blocks. The length of a
904 // state vector cannot be determined until we have made a pass through
905 // the bytecodes counting the possible monitor entries.
906 if (!_got_error) init_basic_blocks();
907 if (!_got_error) setup_method_entry_state();
908 if (!_got_error) interp_all();
909 if (!_got_error) rewrite_refval_conflicts();
910 i++;
911 } while (_conflict && !_got_error);
912 }
913
914 void GenerateOopMap::init_basic_blocks() {
915 // Note: Could consider reserving only the needed space for each BB's state
916 // (entry stack may not be of maximal height for every basic block).
917 // But cumbersome since we don't know the stack heights yet. (Nor the
918 // monitor stack heights...)
919
920 ALLOC_RESOURCE_ARRAY(_basic_blocks, BasicBlock, _bb_count);
921
922 // Make a pass through the bytecodes. Count the number of monitorenters.
923 // This can be used an upper bound on the monitor stack depth in programs
924 // which obey stack discipline with their monitor usage. Initialize the
925 // known information about basic blocks.
926 BytecodeStream j(_method);
927 Bytecodes::Code bytecode;
928
929 int bbNo = 0;
930 int monitor_count = 0;
931 int prev_bci = -1;
932 while( (bytecode = j.next()) >= 0) {
933 if (j.code() == Bytecodes::_monitorenter) {
934 monitor_count++;
935 }
936
937 int bci = j.bci();
938 if (is_bb_header(bci)) {
939 // Initialize the basicblock structure
940 BasicBlock *bb = _basic_blocks + bbNo;
941 bb->_bci = bci;
942 bb->_max_locals = _max_locals;
943 bb->_max_stack = _max_stack;
944 bb->set_changed(false);
945 bb->_stack_top = BasicBlock::_dead_basic_block; // Initialize all basicblocks are dead.
946 bb->_monitor_top = bad_monitors;
947
948 if (bbNo > 0) {
949 _basic_blocks[bbNo - 1]._end_bci = prev_bci;
950 }
951
952 bbNo++;
953 }
954 // Remember prevous bci.
955 prev_bci = bci;
956 }
957 // Set
958 _basic_blocks[bbNo-1]._end_bci = prev_bci;
959
960
961 // Check that the correct number of basicblocks was found
962 if (bbNo !=_bb_count) {
963 if (bbNo < _bb_count) {
964 verify_error("jump into the middle of instruction?");
965 return;
966 } else {
967 verify_error("extra basic blocks - should not happen?");
968 return;
969 }
970 }
971
972 _max_monitors = monitor_count;
973
974 // Now that we have a bound on the depth of the monitor stack, we can
975 // initialize the CellTypeState-related information.
976 init_state();
977
978 // We allocate space for all state-vectors for all basicblocks in one huge
979 // chunk. Then in the next part of the code, we set a pointer in each
980 // _basic_block that points to each piece.
981
982 // The product of bbNo and _state_len can get large if there are lots of
983 // basic blocks and stack/locals/monitors. Need to check to make sure
984 // we don't overflow the capacity of a pointer.
985 if ((unsigned)bbNo > UINTPTR_MAX / sizeof(CellTypeState) / _state_len) {
986 report_error("The amount of memory required to analyze this method "
987 "exceeds addressable range");
988 return;
989 }
990
991 CellTypeState *basicBlockState;
992 ALLOC_RESOURCE_ARRAY(basicBlockState, CellTypeState, bbNo * _state_len);
993 memset(basicBlockState, 0, bbNo * _state_len * sizeof(CellTypeState));
994
995 // Make a pass over the basicblocks and assign their state vectors.
996 for (int blockNum=0; blockNum < bbNo; blockNum++) {
997 BasicBlock *bb = _basic_blocks + blockNum;
998 bb->_state = basicBlockState + blockNum * _state_len;
999
1000 #ifdef ASSERT
1001 if (blockNum + 1 < bbNo) {
1002 address bcp = _method->bcp_from(bb->_end_bci);
1003 int bc_len = Bytecodes::java_length_at(_method(), bcp);
1004 assert(bb->_end_bci + bc_len == bb[1]._bci, "unmatched bci info in basicblock");
1005 }
1006 #endif
1007 }
1008 #ifdef ASSERT
1009 { BasicBlock *bb = &_basic_blocks[bbNo-1];
1010 address bcp = _method->bcp_from(bb->_end_bci);
1011 int bc_len = Bytecodes::java_length_at(_method(), bcp);
1012 assert(bb->_end_bci + bc_len == _method->code_size(), "wrong end bci");
1013 }
1014 #endif
1015
1016 // Mark all alive blocks
1017 mark_reachable_code();
1018 }
1019
1020 void GenerateOopMap::setup_method_entry_state() {
1021
1022 // Initialize all locals to 'uninit' and set stack-height to 0
1023 make_context_uninitialized();
1024
1025 // Initialize CellState type of arguments
1026 methodsig_to_effect(method()->signature(), method()->is_static(), vars());
1027
1028 // If some references must be pre-assigned to null, then set that up
1029 initialize_vars();
1030
1031 // This is the start state
1032 merge_state_into_bb(&_basic_blocks[0]);
1033
1034 assert(_basic_blocks[0].changed(), "we are not getting off the ground");
1035 }
1036
1037 // The instruction at bci is changing size by "delta". Update the basic blocks.
1038 void GenerateOopMap::update_basic_blocks(int bci, int delta,
1039 int new_method_size) {
1040 assert(new_method_size >= method()->code_size() + delta,
1041 "new method size is too small");
1042
1043 _bb_hdr_bits.reinitialize(new_method_size);
1044
1045 for(int k = 0; k < _bb_count; k++) {
1046 if (_basic_blocks[k]._bci > bci) {
1047 _basic_blocks[k]._bci += delta;
1048 _basic_blocks[k]._end_bci += delta;
1049 }
1050 _bb_hdr_bits.at_put(_basic_blocks[k]._bci, true);
1051 }
1052 }
1053
1054 //
1055 // Initvars handling
1056 //
1057
1058 void GenerateOopMap::initialize_vars() {
1059 for (int k = 0; k < _init_vars->length(); k++)
1060 _state[_init_vars->at(k)] = CellTypeState::make_slot_ref(k);
1061 }
1062
1063 void GenerateOopMap::add_to_ref_init_set(int localNo) {
1064
1065 if (TraceNewOopMapGeneration)
1066 tty->print_cr("Added init vars: %d", localNo);
1067
1068 // Is it already in the set?
1069 if (_init_vars->contains(localNo) )
1070 return;
1071
1072 _init_vars->append(localNo);
1073 }
1074
1075 //
1076 // Interpreration code
1077 //
1078
1079 void GenerateOopMap::interp_all() {
1080 bool change = true;
1081
1082 while (change && !_got_error) {
1083 change = false;
1084 for (int i = 0; i < _bb_count && !_got_error; i++) {
1085 BasicBlock *bb = &_basic_blocks[i];
1086 if (bb->changed()) {
1087 if (_got_error) return;
1088 change = true;
1089 bb->set_changed(false);
1090 interp_bb(bb);
1091 }
1092 }
1093 }
1094 }
1095
1096 void GenerateOopMap::interp_bb(BasicBlock *bb) {
1097
1098 // We do not want to do anything in case the basic-block has not been initialized. This
1099 // will happen in the case where there is dead-code hang around in a method.
1100 assert(bb->is_reachable(), "should be reachable or deadcode exist");
1101 restore_state(bb);
1102
1103 BytecodeStream itr(_method);
1104
1105 // Set iterator interval to be the current basicblock
1106 int lim_bci = next_bb_start_pc(bb);
1107 itr.set_interval(bb->_bci, lim_bci);
1108 assert(lim_bci != bb->_bci, "must be at least one instruction in a basicblock");
1109 itr.next(); // read first instruction
1110
1111 // Iterates through all bytecodes except the last in a basic block.
1112 // We handle the last one special, since there is controlflow change.
1113 while(itr.next_bci() < lim_bci && !_got_error) {
1114 if (_has_exceptions || _monitor_top != 0) {
1115 // We do not need to interpret the results of exceptional
1116 // continuation from this instruction when the method has no
1117 // exception handlers and the monitor stack is currently
1118 // empty.
1119 do_exception_edge(&itr);
1120 }
1121 interp1(&itr);
1122 itr.next();
1123 }
1124
1125 // Handle last instruction.
1126 if (!_got_error) {
1127 assert(itr.next_bci() == lim_bci, "must point to end");
1128 if (_has_exceptions || _monitor_top != 0) {
1129 do_exception_edge(&itr);
1130 }
1131 interp1(&itr);
1132
1133 bool fall_through = jump_targets_do(&itr, GenerateOopMap::merge_state, NULL);
1134 if (_got_error) return;
1135
1136 if (itr.code() == Bytecodes::_ret) {
1137 assert(!fall_through, "cannot be set if ret instruction");
1138 // Automatically handles 'wide' ret indicies
1139 ret_jump_targets_do(&itr, GenerateOopMap::merge_state, itr.get_index(), NULL);
1140 } else if (fall_through) {
1141 // Hit end of BB, but the instr. was a fall-through instruction,
1142 // so perform transition as if the BB ended in a "jump".
1143 if (lim_bci != bb[1]._bci) {
1144 verify_error("bytecodes fell through last instruction");
1145 return;
1146 }
1147 merge_state_into_bb(bb + 1);
1148 }
1149 }
1150 }
1151
1152 void GenerateOopMap::do_exception_edge(BytecodeStream* itr) {
1153 // Only check exception edge, if bytecode can trap
1154 if (!Bytecodes::can_trap(itr->code())) return;
1155 switch (itr->code()) {
1156 case Bytecodes::_aload_0:
1157 // These bytecodes can trap for rewriting. We need to assume that
1158 // they do not throw exceptions to make the monitor analysis work.
1159 return;
1160
1161 case Bytecodes::_ireturn:
1162 case Bytecodes::_lreturn:
1163 case Bytecodes::_freturn:
1164 case Bytecodes::_dreturn:
1165 case Bytecodes::_areturn:
1166 case Bytecodes::_return:
1167 // If the monitor stack height is not zero when we leave the method,
1168 // then we are either exiting with a non-empty stack or we have
1169 // found monitor trouble earlier in our analysis. In either case,
1170 // assume an exception could be taken here.
1171 if (_monitor_top == 0) {
1172 return;
1173 }
1174 break;
1175
1176 case Bytecodes::_monitorexit:
1177 // If the monitor stack height is bad_monitors, then we have detected a
1178 // monitor matching problem earlier in the analysis. If the
1179 // monitor stack height is 0, we are about to pop a monitor
1180 // off of an empty stack. In either case, the bytecode
1181 // could throw an exception.
1182 if (_monitor_top != bad_monitors && _monitor_top != 0) {
1183 return;
1184 }
1185 break;
1186 }
1187
1188 if (_has_exceptions) {
1189 int bci = itr->bci();
1190 ExceptionTable exct(method());
1191 for(int i = 0; i< exct.length(); i++) {
1192 int start_pc = exct.start_pc(i);
1193 int end_pc = exct.end_pc(i);
1194 int handler_pc = exct.handler_pc(i);
1195 int catch_type = exct.catch_type_index(i);
1196
1197 if (start_pc <= bci && bci < end_pc) {
1198 BasicBlock *excBB = get_basic_block_at(handler_pc);
1199 guarantee(excBB != NULL, "no basic block for exception");
1200 CellTypeState *excStk = excBB->stack();
1201 CellTypeState *cOpStck = stack();
1202 CellTypeState cOpStck_0 = cOpStck[0];
1203 int cOpStackTop = _stack_top;
1204
1205 // Exception stacks are always the same.
1206 assert(method()->max_stack() > 0, "sanity check");
1207
1208 // We remembered the size and first element of "cOpStck"
1209 // above; now we temporarily set them to the appropriate
1210 // values for an exception handler. */
1211 cOpStck[0] = CellTypeState::make_slot_ref(_max_locals);
1212 _stack_top = 1;
1213
1214 merge_state_into_bb(excBB);
1215
1216 // Now undo the temporary change.
1217 cOpStck[0] = cOpStck_0;
1218 _stack_top = cOpStackTop;
1219
1220 // If this is a "catch all" handler, then we do not need to
1221 // consider any additional handlers.
1222 if (catch_type == 0) {
1223 return;
1224 }
1225 }
1226 }
1227 }
1228
1229 // It is possible that none of the exception handlers would have caught
1230 // the exception. In this case, we will exit the method. We must
1231 // ensure that the monitor stack is empty in this case.
1232 if (_monitor_top == 0) {
1233 return;
1234 }
1235
1236 // We pessimistically assume that this exception can escape the
1237 // method. (It is possible that it will always be caught, but
1238 // we don't care to analyse the types of the catch clauses.)
1239
1240 // We don't set _monitor_top to bad_monitors because there are no successors
1241 // to this exceptional exit.
1242
1243 if (log_is_enabled(Info, monitormismatch) && _monitor_safe) {
1244 // We check _monitor_safe so that we only report the first mismatched
1245 // exceptional exit.
1246 report_monitor_mismatch("non-empty monitor stack at exceptional exit");
1247 }
1248 _monitor_safe = false;
1249
1250 }
1251
1252 void GenerateOopMap::report_monitor_mismatch(const char *msg) {
1253 ResourceMark rm;
1254 outputStream* out = Log(monitormismatch)::info_stream();
1255 out->print("Monitor mismatch in method ");
1256 method()->print_short_name(out);
1257 out->print_cr(": %s", msg);
1258 }
1259
1260 void GenerateOopMap::print_states(outputStream *os,
1261 CellTypeState* vec, int num) {
1262 for (int i = 0; i < num; i++) {
1263 vec[i].print(tty);
1264 }
1265 }
1266
1267 // Print the state values at the current bytecode.
1268 void GenerateOopMap::print_current_state(outputStream *os,
1269 BytecodeStream *currentBC,
1270 bool detailed) {
1271
1272 if (detailed) {
1273 os->print(" %4d vars = ", currentBC->bci());
1274 print_states(os, vars(), _max_locals);
1275 os->print(" %s", Bytecodes::name(currentBC->code()));
1276 switch(currentBC->code()) {
1277 case Bytecodes::_invokevirtual:
1278 case Bytecodes::_invokespecial:
1279 case Bytecodes::_invokestatic:
1280 case Bytecodes::_invokedynamic:
1281 case Bytecodes::_invokeinterface:
1282 int idx = currentBC->has_index_u4() ? currentBC->get_index_u4() : currentBC->get_index_u2_cpcache();
1283 ConstantPool* cp = method()->constants();
1284 int nameAndTypeIdx = cp->name_and_type_ref_index_at(idx);
1285 int signatureIdx = cp->signature_ref_index_at(nameAndTypeIdx);
1286 Symbol* signature = cp->symbol_at(signatureIdx);
1287 os->print("%s", signature->as_C_string());
1288 }
1289 os->cr();
1290 os->print(" stack = ");
1291 print_states(os, stack(), _stack_top);
1292 os->cr();
1293 if (_monitor_top != bad_monitors) {
1294 os->print(" monitors = ");
1295 print_states(os, monitors(), _monitor_top);
1296 } else {
1297 os->print(" [bad monitor stack]");
1298 }
1299 os->cr();
1300 } else {
1301 os->print(" %4d vars = '%s' ", currentBC->bci(), state_vec_to_string(vars(), _max_locals));
1302 os->print(" stack = '%s' ", state_vec_to_string(stack(), _stack_top));
1303 if (_monitor_top != bad_monitors) {
1304 os->print(" monitors = '%s' \t%s", state_vec_to_string(monitors(), _monitor_top), Bytecodes::name(currentBC->code()));
1305 } else {
1306 os->print(" [bad monitor stack]");
1307 }
1308 switch(currentBC->code()) {
1309 case Bytecodes::_invokevirtual:
1310 case Bytecodes::_invokespecial:
1311 case Bytecodes::_invokestatic:
1312 case Bytecodes::_invokedynamic:
1313 case Bytecodes::_invokeinterface:
1314 int idx = currentBC->has_index_u4() ? currentBC->get_index_u4() : currentBC->get_index_u2_cpcache();
1315 ConstantPool* cp = method()->constants();
1316 int nameAndTypeIdx = cp->name_and_type_ref_index_at(idx);
1317 int signatureIdx = cp->signature_ref_index_at(nameAndTypeIdx);
1318 Symbol* signature = cp->symbol_at(signatureIdx);
1319 os->print("%s", signature->as_C_string());
1320 }
1321 os->cr();
1322 }
1323 }
1324
1325 // Sets the current state to be the state after executing the
1326 // current instruction, starting in the current state.
1327 void GenerateOopMap::interp1(BytecodeStream *itr) {
1328 if (TraceNewOopMapGeneration) {
1329 print_current_state(tty, itr, TraceNewOopMapGenerationDetailed);
1330 }
1331
1332 // Should we report the results? Result is reported *before* the instruction at the current bci is executed.
1333 // However, not for calls. For calls we do not want to include the arguments, so we postpone the reporting until
1334 // they have been popped (in method ppl).
1335 if (_report_result == true) {
1336 switch(itr->code()) {
1337 case Bytecodes::_invokevirtual:
1338 case Bytecodes::_invokespecial:
1339 case Bytecodes::_invokestatic:
1340 case Bytecodes::_invokedynamic:
1341 case Bytecodes::_invokeinterface:
1342 _itr_send = itr;
1343 _report_result_for_send = true;
1344 break;
1345 default:
1346 fill_stackmap_for_opcodes(itr, vars(), stack(), _stack_top);
1347 break;
1348 }
1349 }
1350
1351 // abstract interpretation of current opcode
1352 switch(itr->code()) {
1353 case Bytecodes::_nop: break;
1354 case Bytecodes::_goto: break;
1355 case Bytecodes::_goto_w: break;
1356 case Bytecodes::_iinc: break;
1357 case Bytecodes::_return: do_return_monitor_check();
1358 break;
1359
1360 case Bytecodes::_aconst_null:
1361 case Bytecodes::_new: ppush1(CellTypeState::make_line_ref(itr->bci()));
1362 break;
1363
1364 case Bytecodes::_iconst_m1:
1365 case Bytecodes::_iconst_0:
1366 case Bytecodes::_iconst_1:
1367 case Bytecodes::_iconst_2:
1368 case Bytecodes::_iconst_3:
1369 case Bytecodes::_iconst_4:
1370 case Bytecodes::_iconst_5:
1371 case Bytecodes::_fconst_0:
1372 case Bytecodes::_fconst_1:
1373 case Bytecodes::_fconst_2:
1374 case Bytecodes::_bipush:
1375 case Bytecodes::_sipush: ppush1(valCTS); break;
1376
1377 case Bytecodes::_lconst_0:
1378 case Bytecodes::_lconst_1:
1379 case Bytecodes::_dconst_0:
1380 case Bytecodes::_dconst_1: ppush(vvCTS); break;
1381
1382 case Bytecodes::_ldc2_w: ppush(vvCTS); break;
1383
1384 case Bytecodes::_ldc: // fall through:
1385 case Bytecodes::_ldc_w: do_ldc(itr->bci()); break;
1386
1387 case Bytecodes::_iload:
1388 case Bytecodes::_fload: ppload(vCTS, itr->get_index()); break;
1389
1390 case Bytecodes::_lload:
1391 case Bytecodes::_dload: ppload(vvCTS,itr->get_index()); break;
1392
1393 case Bytecodes::_aload: ppload(rCTS, itr->get_index()); break;
1394
1395 case Bytecodes::_iload_0:
1396 case Bytecodes::_fload_0: ppload(vCTS, 0); break;
1397 case Bytecodes::_iload_1:
1398 case Bytecodes::_fload_1: ppload(vCTS, 1); break;
1399 case Bytecodes::_iload_2:
1400 case Bytecodes::_fload_2: ppload(vCTS, 2); break;
1401 case Bytecodes::_iload_3:
1402 case Bytecodes::_fload_3: ppload(vCTS, 3); break;
1403
1404 case Bytecodes::_lload_0:
1405 case Bytecodes::_dload_0: ppload(vvCTS, 0); break;
1406 case Bytecodes::_lload_1:
1407 case Bytecodes::_dload_1: ppload(vvCTS, 1); break;
1408 case Bytecodes::_lload_2:
1409 case Bytecodes::_dload_2: ppload(vvCTS, 2); break;
1410 case Bytecodes::_lload_3:
1411 case Bytecodes::_dload_3: ppload(vvCTS, 3); break;
1412
1413 case Bytecodes::_aload_0: ppload(rCTS, 0); break;
1414 case Bytecodes::_aload_1: ppload(rCTS, 1); break;
1415 case Bytecodes::_aload_2: ppload(rCTS, 2); break;
1416 case Bytecodes::_aload_3: ppload(rCTS, 3); break;
1417
1418 case Bytecodes::_iaload:
1419 case Bytecodes::_faload:
1420 case Bytecodes::_baload:
1421 case Bytecodes::_caload:
1422 case Bytecodes::_saload: pp(vrCTS, vCTS); break;
1423
1424 case Bytecodes::_laload: pp(vrCTS, vvCTS); break;
1425 case Bytecodes::_daload: pp(vrCTS, vvCTS); break;
1426
1427 case Bytecodes::_aaload: pp_new_ref(vrCTS, itr->bci()); break;
1428
1429 case Bytecodes::_istore:
1430 case Bytecodes::_fstore: ppstore(vCTS, itr->get_index()); break;
1431
1432 case Bytecodes::_lstore:
1433 case Bytecodes::_dstore: ppstore(vvCTS, itr->get_index()); break;
1434
1435 case Bytecodes::_astore: do_astore(itr->get_index()); break;
1436
1437 case Bytecodes::_istore_0:
1438 case Bytecodes::_fstore_0: ppstore(vCTS, 0); break;
1439 case Bytecodes::_istore_1:
1440 case Bytecodes::_fstore_1: ppstore(vCTS, 1); break;
1441 case Bytecodes::_istore_2:
1442 case Bytecodes::_fstore_2: ppstore(vCTS, 2); break;
1443 case Bytecodes::_istore_3:
1444 case Bytecodes::_fstore_3: ppstore(vCTS, 3); break;
1445
1446 case Bytecodes::_lstore_0:
1447 case Bytecodes::_dstore_0: ppstore(vvCTS, 0); break;
1448 case Bytecodes::_lstore_1:
1449 case Bytecodes::_dstore_1: ppstore(vvCTS, 1); break;
1450 case Bytecodes::_lstore_2:
1451 case Bytecodes::_dstore_2: ppstore(vvCTS, 2); break;
1452 case Bytecodes::_lstore_3:
1453 case Bytecodes::_dstore_3: ppstore(vvCTS, 3); break;
1454
1455 case Bytecodes::_astore_0: do_astore(0); break;
1456 case Bytecodes::_astore_1: do_astore(1); break;
1457 case Bytecodes::_astore_2: do_astore(2); break;
1458 case Bytecodes::_astore_3: do_astore(3); break;
1459
1460 case Bytecodes::_iastore:
1461 case Bytecodes::_fastore:
1462 case Bytecodes::_bastore:
1463 case Bytecodes::_castore:
1464 case Bytecodes::_sastore: ppop(vvrCTS); break;
1465 case Bytecodes::_lastore:
1466 case Bytecodes::_dastore: ppop(vvvrCTS); break;
1467 case Bytecodes::_aastore: ppop(rvrCTS); break;
1468
1469 case Bytecodes::_pop: ppop_any(1); break;
1470 case Bytecodes::_pop2: ppop_any(2); break;
1471
1472 case Bytecodes::_dup: ppdupswap(1, "11"); break;
1473 case Bytecodes::_dup_x1: ppdupswap(2, "121"); break;
1474 case Bytecodes::_dup_x2: ppdupswap(3, "1321"); break;
1475 case Bytecodes::_dup2: ppdupswap(2, "2121"); break;
1476 case Bytecodes::_dup2_x1: ppdupswap(3, "21321"); break;
1477 case Bytecodes::_dup2_x2: ppdupswap(4, "214321"); break;
1478 case Bytecodes::_swap: ppdupswap(2, "12"); break;
1479
1480 case Bytecodes::_iadd:
1481 case Bytecodes::_fadd:
1482 case Bytecodes::_isub:
1483 case Bytecodes::_fsub:
1484 case Bytecodes::_imul:
1485 case Bytecodes::_fmul:
1486 case Bytecodes::_idiv:
1487 case Bytecodes::_fdiv:
1488 case Bytecodes::_irem:
1489 case Bytecodes::_frem:
1490 case Bytecodes::_ishl:
1491 case Bytecodes::_ishr:
1492 case Bytecodes::_iushr:
1493 case Bytecodes::_iand:
1494 case Bytecodes::_ior:
1495 case Bytecodes::_ixor:
1496 case Bytecodes::_l2f:
1497 case Bytecodes::_l2i:
1498 case Bytecodes::_d2f:
1499 case Bytecodes::_d2i:
1500 case Bytecodes::_fcmpl:
1501 case Bytecodes::_fcmpg: pp(vvCTS, vCTS); break;
1502
1503 case Bytecodes::_ladd:
1504 case Bytecodes::_dadd:
1505 case Bytecodes::_lsub:
1506 case Bytecodes::_dsub:
1507 case Bytecodes::_lmul:
1508 case Bytecodes::_dmul:
1509 case Bytecodes::_ldiv:
1510 case Bytecodes::_ddiv:
1511 case Bytecodes::_lrem:
1512 case Bytecodes::_drem:
1513 case Bytecodes::_land:
1514 case Bytecodes::_lor:
1515 case Bytecodes::_lxor: pp(vvvvCTS, vvCTS); break;
1516
1517 case Bytecodes::_ineg:
1518 case Bytecodes::_fneg:
1519 case Bytecodes::_i2f:
1520 case Bytecodes::_f2i:
1521 case Bytecodes::_i2c:
1522 case Bytecodes::_i2s:
1523 case Bytecodes::_i2b: pp(vCTS, vCTS); break;
1524
1525 case Bytecodes::_lneg:
1526 case Bytecodes::_dneg:
1527 case Bytecodes::_l2d:
1528 case Bytecodes::_d2l: pp(vvCTS, vvCTS); break;
1529
1530 case Bytecodes::_lshl:
1531 case Bytecodes::_lshr:
1532 case Bytecodes::_lushr: pp(vvvCTS, vvCTS); break;
1533
1534 case Bytecodes::_i2l:
1535 case Bytecodes::_i2d:
1536 case Bytecodes::_f2l:
1537 case Bytecodes::_f2d: pp(vCTS, vvCTS); break;
1538
1539 case Bytecodes::_lcmp: pp(vvvvCTS, vCTS); break;
1540 case Bytecodes::_dcmpl:
1541 case Bytecodes::_dcmpg: pp(vvvvCTS, vCTS); break;
1542
1543 case Bytecodes::_ifeq:
1544 case Bytecodes::_ifne:
1545 case Bytecodes::_iflt:
1546 case Bytecodes::_ifge:
1547 case Bytecodes::_ifgt:
1548 case Bytecodes::_ifle:
1549 case Bytecodes::_tableswitch: ppop1(valCTS);
1550 break;
1551 case Bytecodes::_ireturn:
1552 case Bytecodes::_freturn: do_return_monitor_check();
1553 ppop1(valCTS);
1554 break;
1555 case Bytecodes::_if_icmpeq:
1556 case Bytecodes::_if_icmpne:
1557 case Bytecodes::_if_icmplt:
1558 case Bytecodes::_if_icmpge:
1559 case Bytecodes::_if_icmpgt:
1560 case Bytecodes::_if_icmple: ppop(vvCTS);
1561 break;
1562
1563 case Bytecodes::_lreturn: do_return_monitor_check();
1564 ppop(vvCTS);
1565 break;
1566
1567 case Bytecodes::_dreturn: do_return_monitor_check();
1568 ppop(vvCTS);
1569 break;
1570
1571 case Bytecodes::_if_acmpeq:
1572 case Bytecodes::_if_acmpne: ppop(rrCTS); break;
1573
1574 case Bytecodes::_jsr: do_jsr(itr->dest()); break;
1575 case Bytecodes::_jsr_w: do_jsr(itr->dest_w()); break;
1576
1577 case Bytecodes::_getstatic: do_field(true, true, itr->get_index_u2_cpcache(), itr->bci()); break;
1578 case Bytecodes::_putstatic: do_field(false, true, itr->get_index_u2_cpcache(), itr->bci()); break;
1579 case Bytecodes::_getfield: do_field(true, false, itr->get_index_u2_cpcache(), itr->bci()); break;
1580 case Bytecodes::_putfield: do_field(false, false, itr->get_index_u2_cpcache(), itr->bci()); break;
1581
1582 case Bytecodes::_invokevirtual:
1583 case Bytecodes::_invokespecial: do_method(false, false, itr->get_index_u2_cpcache(), itr->bci()); break;
1584 case Bytecodes::_invokestatic: do_method(true, false, itr->get_index_u2_cpcache(), itr->bci()); break;
1585 case Bytecodes::_invokedynamic: do_method(true, false, itr->get_index_u4(), itr->bci()); break;
1586 case Bytecodes::_invokeinterface: do_method(false, true, itr->get_index_u2_cpcache(), itr->bci()); break;
1587 case Bytecodes::_newarray:
1588 case Bytecodes::_anewarray: pp_new_ref(vCTS, itr->bci()); break;
1589 case Bytecodes::_checkcast: do_checkcast(); break;
1590 case Bytecodes::_arraylength:
1591 case Bytecodes::_instanceof: pp(rCTS, vCTS); break;
1592 case Bytecodes::_monitorenter: do_monitorenter(itr->bci()); break;
1593 case Bytecodes::_monitorexit: do_monitorexit(itr->bci()); break;
1594
1595 case Bytecodes::_athrow: // handled by do_exception_edge() BUT ...
1596 // vlh(apple): do_exception_edge() does not get
1597 // called if method has no exception handlers
1598 if ((!_has_exceptions) && (_monitor_top > 0)) {
1599 _monitor_safe = false;
1600 }
1601 break;
1602
1603 case Bytecodes::_areturn: do_return_monitor_check();
1604 ppop1(refCTS);
1605 break;
1606 case Bytecodes::_ifnull:
1607 case Bytecodes::_ifnonnull: ppop1(refCTS); break;
1608 case Bytecodes::_multianewarray: do_multianewarray(*(itr->bcp()+3), itr->bci()); break;
1609
1610 case Bytecodes::_wide: fatal("Iterator should skip this bytecode"); break;
1611 case Bytecodes::_ret: break;
1612
1613 // Java opcodes
1614 case Bytecodes::_lookupswitch: ppop1(valCTS); break;
1615
1616 default:
1617 tty->print("unexpected opcode: %d\n", itr->code());
1618 ShouldNotReachHere();
1619 break;
1620 }
1621 }
1622
1623 void GenerateOopMap::check_type(CellTypeState expected, CellTypeState actual) {
1624 if (!expected.equal_kind(actual)) {
1625 verify_error("wrong type on stack (found: %c expected: %c)", actual.to_char(), expected.to_char());
1626 }
1627 }
1628
1629 void GenerateOopMap::ppstore(CellTypeState *in, int loc_no) {
1630 while(!(*in).is_bottom()) {
1631 CellTypeState expected =*in++;
1632 CellTypeState actual = pop();
1633 check_type(expected, actual);
1634 assert(loc_no >= 0, "sanity check");
1635 set_var(loc_no++, actual);
1636 }
1637 }
1638
1639 void GenerateOopMap::ppload(CellTypeState *out, int loc_no) {
1640 while(!(*out).is_bottom()) {
1641 CellTypeState out1 = *out++;
1642 CellTypeState vcts = get_var(loc_no);
1643 assert(out1.can_be_reference() || out1.can_be_value(),
1644 "can only load refs. and values.");
1645 if (out1.is_reference()) {
1646 assert(loc_no>=0, "sanity check");
1647 if (!vcts.is_reference()) {
1648 // We were asked to push a reference, but the type of the
1649 // variable can be something else
1650 _conflict = true;
1651 if (vcts.can_be_uninit()) {
1652 // It is a ref-uninit conflict (at least). If there are other
1653 // problems, we'll get them in the next round
1654 add_to_ref_init_set(loc_no);
1655 vcts = out1;
1656 } else {
1657 // It wasn't a ref-uninit conflict. So must be a
1658 // ref-val or ref-pc conflict. Split the variable.
1659 record_refval_conflict(loc_no);
1660 vcts = out1;
1661 }
1662 push(out1); // recover...
1663 } else {
1664 push(vcts); // preserve reference.
1665 }
1666 // Otherwise it is a conflict, but one that verification would
1667 // have caught if illegal. In particular, it can't be a topCTS
1668 // resulting from mergeing two difference pcCTS's since the verifier
1669 // would have rejected any use of such a merge.
1670 } else {
1671 push(out1); // handle val/init conflict
1672 }
1673 loc_no++;
1674 }
1675 }
1676
1677 void GenerateOopMap::ppdupswap(int poplen, const char *out) {
1678 CellTypeState actual[5];
1679 assert(poplen < 5, "this must be less than length of actual vector");
1680
1681 // Pop all arguments.
1682 for (int i = 0; i < poplen; i++) {
1683 actual[i] = pop();
1684 }
1685 // Field _state is uninitialized when calling push.
1686 for (int i = poplen; i < 5; i++) {
1687 actual[i] = CellTypeState::uninit;
1688 }
1689
1690 // put them back
1691 char push_ch = *out++;
1692 while (push_ch != '\0') {
1693 int idx = push_ch - '1';
1694 assert(idx >= 0 && idx < poplen, "wrong arguments");
1695 push(actual[idx]);
1696 push_ch = *out++;
1697 }
1698 }
1699
1700 void GenerateOopMap::ppop1(CellTypeState out) {
1701 CellTypeState actual = pop();
1702 check_type(out, actual);
1703 }
1704
1705 void GenerateOopMap::ppop(CellTypeState *out) {
1706 while (!(*out).is_bottom()) {
1707 ppop1(*out++);
1708 }
1709 }
1710
1711 void GenerateOopMap::ppush1(CellTypeState in) {
1712 assert(in.is_reference() | in.is_value(), "sanity check");
1713 push(in);
1714 }
1715
1716 void GenerateOopMap::ppush(CellTypeState *in) {
1717 while (!(*in).is_bottom()) {
1718 ppush1(*in++);
1719 }
1720 }
1721
1722 void GenerateOopMap::pp(CellTypeState *in, CellTypeState *out) {
1723 ppop(in);
1724 ppush(out);
1725 }
1726
1727 void GenerateOopMap::pp_new_ref(CellTypeState *in, int bci) {
1728 ppop(in);
1729 ppush1(CellTypeState::make_line_ref(bci));
1730 }
1731
1732 void GenerateOopMap::ppop_any(int poplen) {
1733 if (_stack_top >= poplen) {
1734 _stack_top -= poplen;
1735 } else {
1736 verify_error("stack underflow");
1737 }
1738 }
1739
1740 // Replace all occurences of the state 'match' with the state 'replace'
1741 // in our current state vector.
1742 void GenerateOopMap::replace_all_CTS_matches(CellTypeState match,
1743 CellTypeState replace) {
1744 int i;
1745 int len = _max_locals + _stack_top;
1746 bool change = false;
1747
1748 for (i = len - 1; i >= 0; i--) {
1749 if (match.equal(_state[i])) {
1750 _state[i] = replace;
1751 }
1752 }
1753
1754 if (_monitor_top > 0) {
1755 int base = _max_locals + _max_stack;
1756 len = base + _monitor_top;
1757 for (i = len - 1; i >= base; i--) {
1758 if (match.equal(_state[i])) {
1759 _state[i] = replace;
1760 }
1761 }
1762 }
1763 }
1764
1765 void GenerateOopMap::do_checkcast() {
1766 CellTypeState actual = pop();
1767 check_type(refCTS, actual);
1768 push(actual);
1769 }
1770
1771 void GenerateOopMap::do_monitorenter(int bci) {
1772 CellTypeState actual = pop();
1773 if (_monitor_top == bad_monitors) {
1774 return;
1775 }
1776
1777 // Bail out when we get repeated locks on an identical monitor. This case
1778 // isn't too hard to handle and can be made to work if supporting nested
1779 // redundant synchronized statements becomes a priority.
1780 //
1781 // See also "Note" in do_monitorexit(), below.
1782 if (actual.is_lock_reference()) {
1783 _monitor_top = bad_monitors;
1784 _monitor_safe = false;
1785
1786 if (log_is_enabled(Info, monitormismatch)) {
1787 report_monitor_mismatch("nested redundant lock -- bailout...");
1788 }
1789 return;
1790 }
1791
1792 CellTypeState lock = CellTypeState::make_lock_ref(bci);
1793 check_type(refCTS, actual);
1794 if (!actual.is_info_top()) {
1795 replace_all_CTS_matches(actual, lock);
1796 monitor_push(lock);
1797 }
1798 }
1799
1800 void GenerateOopMap::do_monitorexit(int bci) {
1801 CellTypeState actual = pop();
1802 if (_monitor_top == bad_monitors) {
1803 return;
1804 }
1805 check_type(refCTS, actual);
1806 CellTypeState expected = monitor_pop();
1807 if (!actual.is_lock_reference() || !expected.equal(actual)) {
1808 // The monitor we are exiting is not verifiably the one
1809 // on the top of our monitor stack. This causes a monitor
1810 // mismatch.
1811 _monitor_top = bad_monitors;
1812 _monitor_safe = false;
1813
1814 // We need to mark this basic block as changed so that
1815 // this monitorexit will be visited again. We need to
1816 // do this to ensure that we have accounted for the
1817 // possibility that this bytecode will throw an
1818 // exception.
1819 BasicBlock* bb = get_basic_block_containing(bci);
1820 guarantee(bb != NULL, "no basic block for bci");
1821 bb->set_changed(true);
1822 bb->_monitor_top = bad_monitors;
1823
1824 if (log_is_enabled(Info, monitormismatch)) {
1825 report_monitor_mismatch("improper monitor pair");
1826 }
1827 } else {
1828 // This code is a fix for the case where we have repeated
1829 // locking of the same object in straightline code. We clear
1830 // out the lock when it is popped from the monitor stack
1831 // and replace it with an unobtrusive reference value that can
1832 // be locked again.
1833 //
1834 // Note: when generateOopMap is fixed to properly handle repeated,
1835 // nested, redundant locks on the same object, then this
1836 // fix will need to be removed at that time.
1837 replace_all_CTS_matches(actual, CellTypeState::make_line_ref(bci));
1838 }
1839 }
1840
1841 void GenerateOopMap::do_return_monitor_check() {
1842 if (_monitor_top > 0) {
1843 // The monitor stack must be empty when we leave the method
1844 // for the monitors to be properly matched.
1845 _monitor_safe = false;
1846
1847 // Since there are no successors to the *return bytecode, it
1848 // isn't necessary to set _monitor_top to bad_monitors.
1849
1850 if (log_is_enabled(Info, monitormismatch)) {
1851 report_monitor_mismatch("non-empty monitor stack at return");
1852 }
1853 }
1854 }
1855
1856 void GenerateOopMap::do_jsr(int targ_bci) {
1857 push(CellTypeState::make_addr(targ_bci));
1858 }
1859
1860
1861
1862 void GenerateOopMap::do_ldc(int bci) {
1863 Bytecode_loadconstant ldc(method(), bci);
1864 ConstantPool* cp = method()->constants();
1865 constantTag tag = cp->tag_at(ldc.pool_index()); // idx is index in resolved_references
1866 BasicType bt = ldc.result_type();
1867 CellTypeState cts;
1868 if (tag.basic_type() == T_OBJECT) {
1869 assert(!tag.is_string_index() && !tag.is_klass_index(), "Unexpected index tag");
1870 assert(bt == T_OBJECT, "Guard is incorrect");
1871 cts = CellTypeState::make_line_ref(bci);
1872 } else {
1873 assert(bt != T_OBJECT, "Guard is incorrect");
1874 cts = valCTS;
1875 }
1876 ppush1(cts);
1877 }
1878
1879 void GenerateOopMap::do_multianewarray(int dims, int bci) {
1880 assert(dims >= 1, "sanity check");
1881 for(int i = dims -1; i >=0; i--) {
1882 ppop1(valCTS);
1883 }
1884 ppush1(CellTypeState::make_line_ref(bci));
1885 }
1886
1887 void GenerateOopMap::do_astore(int idx) {
1888 CellTypeState r_or_p = pop();
1889 if (!r_or_p.is_address() && !r_or_p.is_reference()) {
1890 // We actually expected ref or pc, but we only report that we expected a ref. It does not
1891 // really matter (at least for now)
1892 verify_error("wrong type on stack (found: %c, expected: {pr})", r_or_p.to_char());
1893 return;
1894 }
1895 set_var(idx, r_or_p);
1896 }
1897
1898 // Copies bottom/zero terminated CTS string from "src" into "dst".
1899 // Does NOT terminate with a bottom. Returns the number of cells copied.
1900 int GenerateOopMap::copy_cts(CellTypeState *dst, CellTypeState *src) {
1901 int idx = 0;
1902 while (!src[idx].is_bottom()) {
1903 dst[idx] = src[idx];
1904 idx++;
1905 }
1906 return idx;
1907 }
1908
1909 void GenerateOopMap::do_field(int is_get, int is_static, int idx, int bci) {
1910 // Dig up signature for field in constant pool
1911 ConstantPool* cp = method()->constants();
1912 int nameAndTypeIdx = cp->name_and_type_ref_index_at(idx);
1913 int signatureIdx = cp->signature_ref_index_at(nameAndTypeIdx);
1914 Symbol* signature = cp->symbol_at(signatureIdx);
1915
1916 // Parse signature (espcially simple for fields)
1917 assert(signature->utf8_length() > 0, "field signatures cannot have zero length");
1918 // The signature is UFT8 encoded, but the first char is always ASCII for signatures.
1919 char sigch = (char)*(signature->base());
1920 CellTypeState temp[4];
1921 CellTypeState *eff = sigchar_to_effect(sigch, bci, temp);
1922
1923 CellTypeState in[4];
1924 CellTypeState *out;
1925 int i = 0;
1926
1927 if (is_get) {
1928 out = eff;
1929 } else {
1930 out = epsilonCTS;
1931 i = copy_cts(in, eff);
1932 }
1933 if (!is_static) in[i++] = CellTypeState::ref;
1934 in[i] = CellTypeState::bottom;
1935 assert(i<=3, "sanity check");
1936 pp(in, out);
1937 }
1938
1939 void GenerateOopMap::do_method(int is_static, int is_interface, int idx, int bci) {
1940 // Dig up signature for field in constant pool
1941 ConstantPool* cp = _method->constants();
1942 Symbol* signature = cp->signature_ref_at(idx);
1943
1944 // Parse method signature
1945 CellTypeState out[4];
1946 CellTypeState in[MAXARGSIZE+1]; // Includes result
1947 ComputeCallStack cse(signature);
1948
1949 // Compute return type
1950 int res_length= cse.compute_for_returntype(out);
1951
1952 // Temporary hack.
1953 if (out[0].equal(CellTypeState::ref) && out[1].equal(CellTypeState::bottom)) {
1954 out[0] = CellTypeState::make_line_ref(bci);
1955 }
1956
1957 assert(res_length<=4, "max value should be vv");
1958
1959 // Compute arguments
1960 int arg_length = cse.compute_for_parameters(is_static != 0, in);
1961 assert(arg_length<=MAXARGSIZE, "too many locals");
1962
1963 // Pop arguments
1964 for (int i = arg_length - 1; i >= 0; i--) ppop1(in[i]);// Do args in reverse order.
1965
1966 // Report results
1967 if (_report_result_for_send == true) {
1968 fill_stackmap_for_opcodes(_itr_send, vars(), stack(), _stack_top);
1969 _report_result_for_send = false;
1970 }
1971
1972 // Push return address
1973 ppush(out);
1974 }
1975
1976 // This is used to parse the signature for fields, since they are very simple...
1977 CellTypeState *GenerateOopMap::sigchar_to_effect(char sigch, int bci, CellTypeState *out) {
1978 // Object and array
1979 if (sigch=='L' || sigch=='[') {
1980 out[0] = CellTypeState::make_line_ref(bci);
1981 out[1] = CellTypeState::bottom;
1982 return out;
1983 }
1984 if (sigch == 'J' || sigch == 'D' ) return vvCTS; // Long and Double
1985 if (sigch == 'V' ) return epsilonCTS; // Void
1986 return vCTS; // Otherwise
1987 }
1988
1989 long GenerateOopMap::_total_byte_count = 0;
1990 elapsedTimer GenerateOopMap::_total_oopmap_time;
1991
1992 // This function assumes "bcs" is at a "ret" instruction and that the vars
1993 // state is valid for that instruction. Furthermore, the ret instruction
1994 // must be the last instruction in "bb" (we store information about the
1995 // "ret" in "bb").
1996 void GenerateOopMap::ret_jump_targets_do(BytecodeStream *bcs, jmpFct_t jmpFct, int varNo, int *data) {
1997 CellTypeState ra = vars()[varNo];
1998 if (!ra.is_good_address()) {
1999 verify_error("ret returns from two jsr subroutines?");
2000 return;
2001 }
2002 int target = ra.get_info();
2003
2004 RetTableEntry* rtEnt = _rt.find_jsrs_for_target(target);
2005 int bci = bcs->bci();
2006 for (int i = 0; i < rtEnt->nof_jsrs(); i++) {
2007 int target_bci = rtEnt->jsrs(i);
2008 // Make sure a jrtRet does not set the changed bit for dead basicblock.
2009 BasicBlock* jsr_bb = get_basic_block_containing(target_bci - 1);
2010 debug_only(BasicBlock* target_bb = &jsr_bb[1];)
2011 assert(target_bb == get_basic_block_at(target_bci), "wrong calc. of successor basicblock");
2012 bool alive = jsr_bb->is_alive();
2013 if (TraceNewOopMapGeneration) {
2014 tty->print("pc = %d, ret -> %d alive: %s\n", bci, target_bci, alive ? "true" : "false");
2015 }
2016 if (alive) jmpFct(this, target_bci, data);
2017 }
2018 }
2019
2020 //
2021 // Debug method
2022 //
2023 char* GenerateOopMap::state_vec_to_string(CellTypeState* vec, int len) {
2024 #ifdef ASSERT
2025 int checklen = MAX3(_max_locals, _max_stack, _max_monitors) + 1;
2026 assert(len < checklen, "state_vec_buf overflow");
2027 #endif
2028 for (int i = 0; i < len; i++) _state_vec_buf[i] = vec[i].to_char();
2029 _state_vec_buf[len] = 0;
2030 return _state_vec_buf;
2031 }
2032
2033 void GenerateOopMap::print_time() {
2034 tty->print_cr ("Accumulated oopmap times:");
2035 tty->print_cr ("---------------------------");
2036 tty->print_cr (" Total : %3.3f sec.", GenerateOopMap::_total_oopmap_time.seconds());
2037 tty->print_cr (" (%3.0f bytecodes per sec) ",
2038 GenerateOopMap::_total_byte_count / GenerateOopMap::_total_oopmap_time.seconds());
2039 }
2040
2041 //
2042 // ============ Main Entry Point ===========
2043 //
2044 GenerateOopMap::GenerateOopMap(const methodHandle& method) {
2045 // We have to initialize all variables here, that can be queried directly
2046 _method = method;
2047 _max_locals=0;
2048 _init_vars = NULL;
2049
2050 #ifndef PRODUCT
2051 // If we are doing a detailed trace, include the regular trace information.
2052 if (TraceNewOopMapGenerationDetailed) {
2053 TraceNewOopMapGeneration = true;
2054 }
2055 #endif
2056 }
2057
2058 void GenerateOopMap::compute_map(TRAPS) {
2059 #ifndef PRODUCT
2060 if (TimeOopMap2) {
2061 method()->print_short_name(tty);
2062 tty->print(" ");
2063 }
2064 if (TimeOopMap) {
2065 _total_byte_count += method()->code_size();
2066 }
2067 #endif
2068 TraceTime t_single("oopmap time", TimeOopMap2);
2069 TraceTime t_all(NULL, &_total_oopmap_time, TimeOopMap);
2070
2071 // Initialize values
2072 _got_error = false;
2073 _conflict = false;
2074 _max_locals = method()->max_locals();
2075 _max_stack = method()->max_stack();
2076 _has_exceptions = (method()->has_exception_handler());
2077 _nof_refval_conflicts = 0;
2078 _init_vars = new GrowableArray<intptr_t>(5); // There are seldom more than 5 init_vars
2079 _report_result = false;
2080 _report_result_for_send = false;
2081 _new_var_map = NULL;
2082 _ret_adr_tos = new GrowableArray<intptr_t>(5); // 5 seems like a good number;
2083 _did_rewriting = false;
2084 _did_relocation = false;
2085
2086 if (TraceNewOopMapGeneration) {
2087 tty->print("Method name: %s\n", method()->name()->as_C_string());
2088 if (Verbose) {
2089 _method->print_codes();
2090 tty->print_cr("Exception table:");
2091 ExceptionTable excps(method());
2092 for(int i = 0; i < excps.length(); i ++) {
2093 tty->print_cr("[%d - %d] -> %d",
2094 excps.start_pc(i), excps.end_pc(i), excps.handler_pc(i));
2095 }
2096 }
2097 }
2098
2099 // if no code - do nothing
2100 // compiler needs info
2101 if (method()->code_size() == 0 || _max_locals + method()->max_stack() == 0) {
2102 fill_stackmap_prolog(0);
2103 fill_stackmap_epilog();
2104 return;
2105 }
2106 // Step 1: Compute all jump targets and their return value
2107 if (!_got_error)
2108 _rt.compute_ret_table(_method);
2109
2110 // Step 2: Find all basic blocks and count GC points
2111 if (!_got_error)
2112 mark_bbheaders_and_count_gc_points();
2113
2114 // Step 3: Calculate stack maps
2115 if (!_got_error)
2116 do_interpretation();
2117
2118 // Step 4:Return results
2119 if (!_got_error && report_results())
2120 report_result();
2121
2122 if (_got_error) {
2123 THROW_HANDLE(_exception);
2124 }
2125 }
2126
2127 // Error handling methods
2128 // These methods create an exception for the current thread which is thrown
2129 // at the bottom of the call stack, when it returns to compute_map(). The
2130 // _got_error flag controls execution. NOT TODO: The VM exception propagation
2131 // mechanism using TRAPS/CHECKs could be used here instead but it would need
2132 // to be added as a parameter to every function and checked for every call.
2133 // The tons of extra code it would generate didn't seem worth the change.
2134 //
2135 void GenerateOopMap::error_work(const char *format, va_list ap) {
2136 _got_error = true;
2137 char msg_buffer[512];
2138 vsnprintf(msg_buffer, sizeof(msg_buffer), format, ap);
2139 // Append method name
2140 char msg_buffer2[512];
2141 jio_snprintf(msg_buffer2, sizeof(msg_buffer2), "%s in method %s", msg_buffer, method()->name()->as_C_string());
2142 _exception = Exceptions::new_exception(Thread::current(),
2143 vmSymbols::java_lang_LinkageError(), msg_buffer2);
2144 }
2145
2146 void GenerateOopMap::report_error(const char *format, ...) {
2147 va_list ap;
2148 va_start(ap, format);
2149 error_work(format, ap);
2150 }
2151
2152 void GenerateOopMap::verify_error(const char *format, ...) {
2153 // We do not distinguish between different types of errors for verification
2154 // errors. Let the verifier give a better message.
2155 const char *msg = "Illegal class file encountered. Try running with -Xverify:all";
2156 _got_error = true;
2157 // Append method name
2158 char msg_buffer2[512];
2159 jio_snprintf(msg_buffer2, sizeof(msg_buffer2), "%s in method %s", msg,
2160 method()->name()->as_C_string());
2161 _exception = Exceptions::new_exception(Thread::current(),
2162 vmSymbols::java_lang_LinkageError(), msg_buffer2);
2163 }
2164
2165 //
2166 // Report result opcodes
2167 //
2168 void GenerateOopMap::report_result() {
2169
2170 if (TraceNewOopMapGeneration) tty->print_cr("Report result pass");
2171
2172 // We now want to report the result of the parse
2173 _report_result = true;
2174
2175 // Prolog code
2176 fill_stackmap_prolog(_gc_points);
2177
2178 // Mark everything changed, then do one interpretation pass.
2179 for (int i = 0; i<_bb_count; i++) {
2180 if (_basic_blocks[i].is_reachable()) {
2181 _basic_blocks[i].set_changed(true);
2182 interp_bb(&_basic_blocks[i]);
2183 }
2184 }
2185
2186 // Note: Since we are skipping dead-code when we are reporting results, then
2187 // the no. of encountered gc-points might be fewer than the previously number
2188 // we have counted. (dead-code is a pain - it should be removed before we get here)
2189 fill_stackmap_epilog();
2190
2191 // Report initvars
2192 fill_init_vars(_init_vars);
2193
2194 _report_result = false;
2195 }
2196
2197 void GenerateOopMap::result_for_basicblock(int bci) {
2198 if (TraceNewOopMapGeneration) tty->print_cr("Report result pass for basicblock");
2199
2200 // We now want to report the result of the parse
2201 _report_result = true;
2202
2203 // Find basicblock and report results
2204 BasicBlock* bb = get_basic_block_containing(bci);
2205 guarantee(bb != NULL, "no basic block for bci");
2206 assert(bb->is_reachable(), "getting result from unreachable basicblock");
2207 bb->set_changed(true);
2208 interp_bb(bb);
2209 }
2210
2211 //
2212 // Conflict handling code
2213 //
2214
2215 void GenerateOopMap::record_refval_conflict(int varNo) {
2216 assert(varNo>=0 && varNo< _max_locals, "index out of range");
2217
2218 if (TraceOopMapRewrites) {
2219 tty->print("### Conflict detected (local no: %d)\n", varNo);
2220 }
2221
2222 if (!_new_var_map) {
2223 _new_var_map = NEW_RESOURCE_ARRAY(int, _max_locals);
2224 for (int k = 0; k < _max_locals; k++) _new_var_map[k] = k;
2225 }
2226
2227 if ( _new_var_map[varNo] == varNo) {
2228 // Check if max. number of locals has been reached
2229 if (_max_locals + _nof_refval_conflicts >= MAX_LOCAL_VARS) {
2230 report_error("Rewriting exceeded local variable limit");
2231 return;
2232 }
2233 _new_var_map[varNo] = _max_locals + _nof_refval_conflicts;
2234 _nof_refval_conflicts++;
2235 }
2236 }
2237
2238 void GenerateOopMap::rewrite_refval_conflicts()
2239 {
2240 // We can get here two ways: Either a rewrite conflict was detected, or
2241 // an uninitialize reference was detected. In the second case, we do not
2242 // do any rewriting, we just want to recompute the reference set with the
2243 // new information
2244
2245 int nof_conflicts = 0; // Used for debugging only
2246
2247 if ( _nof_refval_conflicts == 0 )
2248 return;
2249
2250 // Check if rewrites are allowed in this parse.
2251 if (!allow_rewrites() && !IgnoreRewrites) {
2252 fatal("Rewriting method not allowed at this stage");
2253 }
2254
2255
2256 // This following flag is to tempoary supress rewrites. The locals that might conflict will
2257 // all be set to contain values. This is UNSAFE - however, until the rewriting has been completely
2258 // tested it is nice to have.
2259 if (IgnoreRewrites) {
2260 if (Verbose) {
2261 tty->print("rewrites suppressed for local no. ");
2262 for (int l = 0; l < _max_locals; l++) {
2263 if (_new_var_map[l] != l) {
2264 tty->print("%d ", l);
2265 vars()[l] = CellTypeState::value;
2266 }
2267 }
2268 tty->cr();
2269 }
2270
2271 // That was that...
2272 _new_var_map = NULL;
2273 _nof_refval_conflicts = 0;
2274 _conflict = false;
2275
2276 return;
2277 }
2278
2279 // Tracing flag
2280 _did_rewriting = true;
2281
2282 if (TraceOopMapRewrites) {
2283 tty->print_cr("ref/value conflict for method %s - bytecodes are getting rewritten", method()->name()->as_C_string());
2284 method()->print();
2285 method()->print_codes();
2286 }
2287
2288 assert(_new_var_map!=NULL, "nothing to rewrite");
2289 assert(_conflict==true, "We should not be here");
2290
2291 compute_ret_adr_at_TOS();
2292 if (!_got_error) {
2293 for (int k = 0; k < _max_locals && !_got_error; k++) {
2294 if (_new_var_map[k] != k) {
2295 if (TraceOopMapRewrites) {
2296 tty->print_cr("Rewriting: %d -> %d", k, _new_var_map[k]);
2297 }
2298 rewrite_refval_conflict(k, _new_var_map[k]);
2299 if (_got_error) return;
2300 nof_conflicts++;
2301 }
2302 }
2303 }
2304
2305 assert(nof_conflicts == _nof_refval_conflicts, "sanity check");
2306
2307 // Adjust the number of locals
2308 method()->set_max_locals(_max_locals+_nof_refval_conflicts);
2309 _max_locals += _nof_refval_conflicts;
2310
2311 // That was that...
2312 _new_var_map = NULL;
2313 _nof_refval_conflicts = 0;
2314 }
2315
2316 void GenerateOopMap::rewrite_refval_conflict(int from, int to) {
2317 bool startOver;
2318 do {
2319 // Make sure that the BytecodeStream is constructed in the loop, since
2320 // during rewriting a new method oop is going to be used, and the next time
2321 // around we want to use that.
2322 BytecodeStream bcs(_method);
2323 startOver = false;
2324
2325 while( !startOver && !_got_error &&
2326 // test bcs in case method changed and it became invalid
2327 bcs.next() >=0) {
2328 startOver = rewrite_refval_conflict_inst(&bcs, from, to);
2329 }
2330 } while (startOver && !_got_error);
2331 }
2332
2333 /* If the current instruction is one that uses local variable "from"
2334 in a ref way, change it to use "to". There's a subtle reason why we
2335 renumber the ref uses and not the non-ref uses: non-ref uses may be
2336 2 slots wide (double, long) which would necessitate keeping track of
2337 whether we should add one or two variables to the method. If the change
2338 affected the width of some instruction, returns "TRUE"; otherwise, returns "FALSE".
2339 Another reason for moving ref's value is for solving (addr, ref) conflicts, which
2340 both uses aload/astore methods.
2341 */
2342 bool GenerateOopMap::rewrite_refval_conflict_inst(BytecodeStream *itr, int from, int to) {
2343 Bytecodes::Code bc = itr->code();
2344 int index;
2345 int bci = itr->bci();
2346
2347 if (is_aload(itr, &index) && index == from) {
2348 if (TraceOopMapRewrites) {
2349 tty->print_cr("Rewriting aload at bci: %d", bci);
2350 }
2351 return rewrite_load_or_store(itr, Bytecodes::_aload, Bytecodes::_aload_0, to);
2352 }
2353
2354 if (is_astore(itr, &index) && index == from) {
2355 if (!stack_top_holds_ret_addr(bci)) {
2356 if (TraceOopMapRewrites) {
2357 tty->print_cr("Rewriting astore at bci: %d", bci);
2358 }
2359 return rewrite_load_or_store(itr, Bytecodes::_astore, Bytecodes::_astore_0, to);
2360 } else {
2361 if (TraceOopMapRewrites) {
2362 tty->print_cr("Supress rewriting of astore at bci: %d", bci);
2363 }
2364 }
2365 }
2366
2367 return false;
2368 }
2369
2370 // The argument to this method is:
2371 // bc : Current bytecode
2372 // bcN : either _aload or _astore
2373 // bc0 : either _aload_0 or _astore_0
2374 bool GenerateOopMap::rewrite_load_or_store(BytecodeStream *bcs, Bytecodes::Code bcN, Bytecodes::Code bc0, unsigned int varNo) {
2375 assert(bcN == Bytecodes::_astore || bcN == Bytecodes::_aload, "wrong argument (bcN)");
2376 assert(bc0 == Bytecodes::_astore_0 || bc0 == Bytecodes::_aload_0, "wrong argument (bc0)");
2377 int ilen = Bytecodes::length_at(_method(), bcs->bcp());
2378 int newIlen;
2379
2380 if (ilen == 4) {
2381 // Original instruction was wide; keep it wide for simplicity
2382 newIlen = 4;
2383 } else if (varNo < 4)
2384 newIlen = 1;
2385 else if (varNo >= 256)
2386 newIlen = 4;
2387 else
2388 newIlen = 2;
2389
2390 // If we need to relocate in order to patch the byte, we
2391 // do the patching in a temp. buffer, that is passed to the reloc.
2392 // The patching of the bytecode stream is then done by the Relocator.
2393 // This is neccesary, since relocating the instruction at a certain bci, might
2394 // also relocate that instruction, e.g., if a _goto before it gets widen to a _goto_w.
2395 // Hence, we do not know which bci to patch after relocation.
2396
2397 assert(newIlen <= 4, "sanity check");
2398 u_char inst_buffer[4]; // Max. instruction size is 4.
2399 address bcp;
2400
2401 if (newIlen != ilen) {
2402 // Relocation needed do patching in temp. buffer
2403 bcp = (address)inst_buffer;
2404 } else {
2405 bcp = _method->bcp_from(bcs->bci());
2406 }
2407
2408 // Patch either directly in Method* or in temp. buffer
2409 if (newIlen == 1) {
2410 assert(varNo < 4, "varNo too large");
2411 *bcp = bc0 + varNo;
2412 } else if (newIlen == 2) {
2413 assert(varNo < 256, "2-byte index needed!");
2414 *(bcp + 0) = bcN;
2415 *(bcp + 1) = varNo;
2416 } else {
2417 assert(newIlen == 4, "Wrong instruction length");
2418 *(bcp + 0) = Bytecodes::_wide;
2419 *(bcp + 1) = bcN;
2420 Bytes::put_Java_u2(bcp+2, varNo);
2421 }
2422
2423 if (newIlen != ilen) {
2424 expand_current_instr(bcs->bci(), ilen, newIlen, inst_buffer);
2425 }
2426
2427
2428 return (newIlen != ilen);
2429 }
2430
2431 class RelocCallback : public RelocatorListener {
2432 private:
2433 GenerateOopMap* _gom;
2434 public:
2435 RelocCallback(GenerateOopMap* gom) { _gom = gom; };
2436
2437 // Callback method
2438 virtual void relocated(int bci, int delta, int new_code_length) {
2439 _gom->update_basic_blocks (bci, delta, new_code_length);
2440 _gom->update_ret_adr_at_TOS(bci, delta);
2441 _gom->_rt.update_ret_table (bci, delta);
2442 }
2443 };
2444
2445 // Returns true if expanding was succesful. Otherwise, reports an error and
2446 // returns false.
2447 void GenerateOopMap::expand_current_instr(int bci, int ilen, int newIlen, u_char inst_buffer[]) {
2448 Thread *THREAD = Thread::current(); // Could really have TRAPS argument.
2449 RelocCallback rcb(this);
2450 Relocator rc(_method, &rcb);
2451 methodHandle m= rc.insert_space_at(bci, newIlen, inst_buffer, THREAD);
2452 if (m.is_null() || HAS_PENDING_EXCEPTION) {
2453 report_error("could not rewrite method - exception occurred or bytecode buffer overflow");
2454 return;
2455 }
2456
2457 // Relocator returns a new method oop.
2458 _did_relocation = true;
2459 _method = m;
2460 }
2461
2462
2463 bool GenerateOopMap::is_astore(BytecodeStream *itr, int *index) {
2464 Bytecodes::Code bc = itr->code();
2465 switch(bc) {
2466 case Bytecodes::_astore_0:
2467 case Bytecodes::_astore_1:
2468 case Bytecodes::_astore_2:
2469 case Bytecodes::_astore_3:
2470 *index = bc - Bytecodes::_astore_0;
2471 return true;
2472 case Bytecodes::_astore:
2473 *index = itr->get_index();
2474 return true;
2475 }
2476 return false;
2477 }
2478
2479 bool GenerateOopMap::is_aload(BytecodeStream *itr, int *index) {
2480 Bytecodes::Code bc = itr->code();
2481 switch(bc) {
2482 case Bytecodes::_aload_0:
2483 case Bytecodes::_aload_1:
2484 case Bytecodes::_aload_2:
2485 case Bytecodes::_aload_3:
2486 *index = bc - Bytecodes::_aload_0;
2487 return true;
2488
2489 case Bytecodes::_aload:
2490 *index = itr->get_index();
2491 return true;
2492 }
2493 return false;
2494 }
2495
2496
2497 // Return true iff the top of the operand stack holds a return address at
2498 // the current instruction
2499 bool GenerateOopMap::stack_top_holds_ret_addr(int bci) {
2500 for(int i = 0; i < _ret_adr_tos->length(); i++) {
2501 if (_ret_adr_tos->at(i) == bci)
2502 return true;
2503 }
2504
2505 return false;
2506 }
2507
2508 void GenerateOopMap::compute_ret_adr_at_TOS() {
2509 assert(_ret_adr_tos != NULL, "must be initialized");
2510 _ret_adr_tos->clear();
2511
2512 for (int i = 0; i < bb_count(); i++) {
2513 BasicBlock* bb = &_basic_blocks[i];
2514
2515 // Make sure to only check basicblocks that are reachable
2516 if (bb->is_reachable()) {
2517
2518 // For each Basic block we check all instructions
2519 BytecodeStream bcs(_method);
2520 bcs.set_interval(bb->_bci, next_bb_start_pc(bb));
2521
2522 restore_state(bb);
2523
2524 while (bcs.next()>=0 && !_got_error) {
2525 // TDT: should this be is_good_address() ?
2526 if (_stack_top > 0 && stack()[_stack_top-1].is_address()) {
2527 _ret_adr_tos->append(bcs.bci());
2528 if (TraceNewOopMapGeneration) {
2529 tty->print_cr("Ret_adr TOS at bci: %d", bcs.bci());
2530 }
2531 }
2532 interp1(&bcs);
2533 }
2534 }
2535 }
2536 }
2537
2538 void GenerateOopMap::update_ret_adr_at_TOS(int bci, int delta) {
2539 for(int i = 0; i < _ret_adr_tos->length(); i++) {
2540 int v = _ret_adr_tos->at(i);
2541 if (v > bci) _ret_adr_tos->at_put(i, v + delta);
2542 }
2543 }
2544
2545 // ===================================================================
2546
2547 #ifndef PRODUCT
2548 int ResolveOopMapConflicts::_nof_invocations = 0;
2549 int ResolveOopMapConflicts::_nof_rewrites = 0;
2550 int ResolveOopMapConflicts::_nof_relocations = 0;
2551 #endif
2552
2553 methodHandle ResolveOopMapConflicts::do_potential_rewrite(TRAPS) {
2554 compute_map(CHECK_(methodHandle()));
2555
2556 #ifndef PRODUCT
2557 // Tracking and statistics
2558 if (PrintRewrites) {
2559 _nof_invocations++;
2560 if (did_rewriting()) {
2561 _nof_rewrites++;
2562 if (did_relocation()) _nof_relocations++;
2563 tty->print("Method was rewritten %s: ", (did_relocation()) ? "and relocated" : "");
2564 method()->print_value(); tty->cr();
2565 tty->print_cr("Cand.: %d rewrts: %d (%d%%) reloc.: %d (%d%%)",
2566 _nof_invocations,
2567 _nof_rewrites, (_nof_rewrites * 100) / _nof_invocations,
2568 _nof_relocations, (_nof_relocations * 100) / _nof_invocations);
2569 }
2570 }
2571 #endif
2572 return methodHandle(THREAD, method());
2573 }