1 /*
2 * Copyright (c) 1997, 2022, 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 "classfile/vmSymbols.hpp"
27 #include "interpreter/bytecodeStream.hpp"
28 #include "logging/log.hpp"
29 #include "logging/logStream.hpp"
30 #include "memory/allocation.inline.hpp"
31 #include "memory/resourceArea.hpp"
32 #include "oops/constantPool.hpp"
33 #include "oops/generateOopMap.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "oops/symbol.hpp"
36 #include "runtime/handles.inline.hpp"
37 #include "runtime/java.hpp"
38 #include "runtime/os.hpp"
39 #include "runtime/relocator.hpp"
40 #include "runtime/timerTrace.hpp"
41 #include "utilities/bitMap.inline.hpp"
42 #include "utilities/ostream.hpp"
43
44 //
45 //
46 // Compute stack layouts for each instruction in method.
47 //
48 // Problems:
49 // - What to do about jsr with different types of local vars?
50 // Need maps that are conditional on jsr path?
51 // - Jsr and exceptions should be done more efficiently (the retAddr stuff)
52 //
53 // Alternative:
54 // - Could extend verifier to provide this information.
55 // For: one fewer abstract interpreter to maintain. Against: the verifier
56 // solves a bigger problem so slower (undesirable to force verification of
57 // everything?).
58 //
59 // Algorithm:
60 // Partition bytecodes into basic blocks
61 // For each basic block: store entry state (vars, stack). For instructions
62 // inside basic blocks we do not store any state (instead we recompute it
63 // from state produced by previous instruction).
64 //
65 // Perform abstract interpretation of bytecodes over this lattice:
66 //
67 // _--'#'--_
68 // / / \ \
69 // / / \ \
70 // / | | \
71 // 'r' 'v' 'p' ' '
72 // \ | | /
73 // \ \ / /
74 // \ \ / /
75 // -- '@' --
76 //
77 // '#' top, result of conflict merge
78 // 'r' reference type
79 // 'v' value type
80 // 'p' pc type for jsr/ret
81 // ' ' uninitialized; never occurs on operand stack in Java
82 // '@' bottom/unexecuted; initial state each bytecode.
83 //
84 // Basic block headers are the only merge points. We use this iteration to
85 // compute the information:
86 //
87 // find basic blocks;
88 // initialize them with uninitialized state;
89 // initialize first BB according to method signature;
90 // mark first BB changed
91 // while (some BB is changed) do {
92 // perform abstract interpration of all bytecodes in BB;
93 // merge exit state of BB into entry state of all successor BBs,
94 // noting if any of these change;
95 // }
96 //
97 // One additional complication is necessary. The jsr instruction pushes
98 // a return PC on the stack (a 'p' type in the abstract interpretation).
99 // To be able to process "ret" bytecodes, we keep track of these return
100 // PC's in a 'retAddrs' structure in abstract interpreter context (when
101 // processing a "ret" bytecodes, it is not sufficient to know that it gets
102 // an argument of the right type 'p'; we need to know which address it
103 // returns to).
104 //
105 // (Note this comment is borrowed form the original author of the algorithm)
106
107 // ComputeCallStack
108 //
109 // Specialization of SignatureIterator - compute the effects of a call
110 //
111 class ComputeCallStack : public SignatureIterator {
112 CellTypeState *_effect;
113 int _idx;
114
115 void setup();
116 void set(CellTypeState state) { _effect[_idx++] = state; }
117 int length() { return _idx; };
118
119 friend class SignatureIterator; // so do_parameters_on can call do_type
120 void do_type(BasicType type, bool for_return = false) {
121 if (for_return && type == T_VOID) {
122 set(CellTypeState::bottom);
123 } else if (is_reference_type(type)) {
124 set(CellTypeState::ref);
125 } else {
126 assert(is_java_primitive(type), "");
127 set(CellTypeState::value);
128 if (is_double_word_type(type)) {
129 set(CellTypeState::value);
130 }
131 }
132 }
133
134 public:
135 ComputeCallStack(Symbol* signature) : SignatureIterator(signature) {};
136
137 // Compute methods
138 int compute_for_parameters(bool is_static, CellTypeState *effect) {
139 _idx = 0;
140 _effect = effect;
141
142 if (!is_static) {
143 effect[_idx++] = CellTypeState::ref;
144 }
145
146 do_parameters_on(this);
147
148 return length();
149 };
150
151 int compute_for_returntype(CellTypeState *effect) {
152 _idx = 0;
153 _effect = effect;
154 do_type(return_type(), true);
155 set(CellTypeState::bottom); // Always terminate with a bottom state, so ppush works
156
157 return length();
158 }
159 };
160
161 //=========================================================================================
162 // ComputeEntryStack
163 //
164 // Specialization of SignatureIterator - in order to set up first stack frame
165 //
166 class ComputeEntryStack : public SignatureIterator {
167 CellTypeState *_effect;
168 int _idx;
169
170 void setup();
171 void set(CellTypeState state) { _effect[_idx++] = state; }
172 int length() { return _idx; };
173
174 friend class SignatureIterator; // so do_parameters_on can call do_type
175 void do_type(BasicType type, bool for_return = false) {
176 if (for_return && type == T_VOID) {
177 set(CellTypeState::bottom);
178 } else if (is_reference_type(type)) {
179 set(CellTypeState::make_slot_ref(_idx));
180 } else {
181 assert(is_java_primitive(type), "");
182 set(CellTypeState::value);
183 if (is_double_word_type(type)) {
184 set(CellTypeState::value);
185 }
186 }
187 }
188
189 public:
190 ComputeEntryStack(Symbol* signature) : SignatureIterator(signature) {};
191
192 // Compute methods
193 int compute_for_parameters(bool is_static, CellTypeState *effect) {
194 _idx = 0;
195 _effect = effect;
196
197 if (!is_static)
198 effect[_idx++] = CellTypeState::make_slot_ref(0);
199
200 do_parameters_on(this);
201
202 return length();
203 };
204
205 int compute_for_returntype(CellTypeState *effect) {
206 _idx = 0;
207 _effect = effect;
208 do_type(return_type(), true);
209 set(CellTypeState::bottom); // Always terminate with a bottom state, so ppush works
210
211 return length();
212 }
213 };
214
215 //=====================================================================================
216 //
217 // Implementation of RetTable/RetTableEntry
218 //
219 // Contains function to itereate through all bytecodes
220 // and find all return entry points
221 //
222 int RetTable::_init_nof_entries = 10;
223 int RetTableEntry::_init_nof_jsrs = 5;
224
225 RetTableEntry::RetTableEntry(int target, RetTableEntry *next) {
226 _target_bci = target;
227 _jsrs = new GrowableArray<intptr_t>(_init_nof_jsrs);
228 _next = next;
229 }
230
231 void RetTableEntry::add_delta(int bci, int delta) {
232 if (_target_bci > bci) _target_bci += delta;
233
234 for (int k = 0; k < _jsrs->length(); k++) {
235 int jsr = _jsrs->at(k);
236 if (jsr > bci) _jsrs->at_put(k, jsr+delta);
237 }
238 }
239
240 void RetTable::compute_ret_table(const methodHandle& method) {
241 BytecodeStream i(method);
242 Bytecodes::Code bytecode;
243
244 while( (bytecode = i.next()) >= 0) {
245 switch (bytecode) {
246 case Bytecodes::_jsr:
247 add_jsr(i.next_bci(), i.dest());
248 break;
249 case Bytecodes::_jsr_w:
250 add_jsr(i.next_bci(), i.dest_w());
251 break;
252 default:
253 break;
254 }
255 }
256 }
257
258 void RetTable::add_jsr(int return_bci, int target_bci) {
259 RetTableEntry* entry = _first;
260
261 // Scan table for entry
262 for (;entry && entry->target_bci() != target_bci; entry = entry->next());
263
264 if (!entry) {
265 // Allocate new entry and put in list
266 entry = new RetTableEntry(target_bci, _first);
267 _first = entry;
268 }
269
270 // Now "entry" is set. Make sure that the entry is initialized
271 // and has room for the new jsr.
272 entry->add_jsr(return_bci);
273 }
274
275 RetTableEntry* RetTable::find_jsrs_for_target(int targBci) {
276 RetTableEntry *cur = _first;
277
278 while(cur) {
279 assert(cur->target_bci() != -1, "sanity check");
280 if (cur->target_bci() == targBci) return cur;
281 cur = cur->next();
282 }
283 ShouldNotReachHere();
284 return NULL;
285 }
286
287 // The instruction at bci is changing size by "delta". Update the return map.
288 void RetTable::update_ret_table(int bci, int delta) {
289 RetTableEntry *cur = _first;
290 while(cur) {
291 cur->add_delta(bci, delta);
292 cur = cur->next();
293 }
294 }
295
296 //
297 // Celltype state
298 //
299
300 CellTypeState CellTypeState::bottom = CellTypeState::make_bottom();
301 CellTypeState CellTypeState::uninit = CellTypeState::make_any(uninit_value);
302 CellTypeState CellTypeState::ref = CellTypeState::make_any(ref_conflict);
303 CellTypeState CellTypeState::value = CellTypeState::make_any(val_value);
304 CellTypeState CellTypeState::refUninit = CellTypeState::make_any(ref_conflict | uninit_value);
305 CellTypeState CellTypeState::top = CellTypeState::make_top();
306 CellTypeState CellTypeState::addr = CellTypeState::make_any(addr_conflict);
307
308 // Commonly used constants
309 static CellTypeState epsilonCTS[1] = { CellTypeState::bottom };
310 static CellTypeState refCTS = CellTypeState::ref;
311 static CellTypeState valCTS = CellTypeState::value;
312 static CellTypeState vCTS[2] = { CellTypeState::value, CellTypeState::bottom };
313 static CellTypeState rCTS[2] = { CellTypeState::ref, CellTypeState::bottom };
314 static CellTypeState rrCTS[3] = { CellTypeState::ref, CellTypeState::ref, CellTypeState::bottom };
315 static CellTypeState vrCTS[3] = { CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
316 static CellTypeState vvCTS[3] = { CellTypeState::value, CellTypeState::value, CellTypeState::bottom };
317 static CellTypeState rvrCTS[4] = { CellTypeState::ref, CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
318 static CellTypeState vvrCTS[4] = { CellTypeState::value, CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
319 static CellTypeState vvvCTS[4] = { CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::bottom };
320 static CellTypeState vvvrCTS[5] = { CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::ref, CellTypeState::bottom };
321 static CellTypeState vvvvCTS[5] = { CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::value, CellTypeState::bottom };
322
323 char CellTypeState::to_char() const {
324 if (can_be_reference()) {
325 if (can_be_value() || can_be_address())
326 return '#'; // Conflict that needs to be rewritten
327 else
328 return 'r';
329 } else if (can_be_value())
330 return 'v';
331 else if (can_be_address())
332 return 'p';
333 else if (can_be_uninit())
334 return ' ';
335 else
336 return '@';
337 }
338
339
340 // Print a detailed CellTypeState. Indicate all bits that are set. If
341 // the CellTypeState represents an address or a reference, print the
342 // value of the additional information.
343 void CellTypeState::print(outputStream *os) {
344 if (can_be_address()) {
345 os->print("(p");
346 } else {
347 os->print("( ");
348 }
349 if (can_be_reference()) {
350 os->print("r");
351 } else {
352 os->print(" ");
353 }
354 if (can_be_value()) {
355 os->print("v");
356 } else {
357 os->print(" ");
358 }
359 if (can_be_uninit()) {
360 os->print("u|");
361 } else {
362 os->print(" |");
363 }
364 if (is_info_top()) {
365 os->print("Top)");
366 } else if (is_info_bottom()) {
367 os->print("Bot)");
368 } else {
369 if (is_reference()) {
370 int info = get_info();
371 int data = info & ~(ref_not_lock_bit | ref_slot_bit);
372 if (info & ref_not_lock_bit) {
373 // Not a monitor lock reference.
374 if (info & ref_slot_bit) {
375 // slot
376 os->print("slot%d)", data);
377 } else {
378 // line
379 os->print("line%d)", data);
380 }
381 } else {
382 // lock
383 os->print("lock%d)", data);
384 }
385 } else {
386 os->print("%d)", get_info());
387 }
388 }
389 }
390
391 //
392 // Basicblock handling methods
393 //
394
395 void GenerateOopMap::initialize_bb() {
396 _gc_points = 0;
397 _bb_count = 0;
398 _bb_hdr_bits.reinitialize(method()->code_size());
399 }
400
401 void GenerateOopMap::bb_mark_fct(GenerateOopMap *c, int bci, int *data) {
402 assert(bci>= 0 && bci < c->method()->code_size(), "index out of bounds");
403 if (c->is_bb_header(bci))
404 return;
405
406 if (TraceNewOopMapGeneration) {
407 tty->print_cr("Basicblock#%d begins at: %d", c->_bb_count, bci);
408 }
409 c->set_bbmark_bit(bci);
410 c->_bb_count++;
411 }
412
413
414 void GenerateOopMap::mark_bbheaders_and_count_gc_points() {
415 initialize_bb();
416
417 bool fellThrough = false; // False to get first BB marked.
418
419 // First mark all exception handlers as start of a basic-block
420 ExceptionTable excps(method());
421 for(int i = 0; i < excps.length(); i ++) {
422 bb_mark_fct(this, excps.handler_pc(i), NULL);
423 }
424
425 // Then iterate through the code
426 BytecodeStream bcs(_method);
427 Bytecodes::Code bytecode;
428
429 while( (bytecode = bcs.next()) >= 0) {
430 int bci = bcs.bci();
431
432 if (!fellThrough)
433 bb_mark_fct(this, bci, NULL);
434
435 fellThrough = jump_targets_do(&bcs, &GenerateOopMap::bb_mark_fct, NULL);
436
437 /* We will also mark successors of jsr's as basic block headers. */
438 switch (bytecode) {
439 case Bytecodes::_jsr:
440 assert(!fellThrough, "should not happen");
441 bb_mark_fct(this, bci + Bytecodes::length_for(bytecode), NULL);
442 break;
443 case Bytecodes::_jsr_w:
444 assert(!fellThrough, "should not happen");
445 bb_mark_fct(this, bci + Bytecodes::length_for(bytecode), NULL);
446 break;
447 default:
448 break;
449 }
450
451 if (possible_gc_point(&bcs))
452 _gc_points++;
453 }
454 }
455
456 void GenerateOopMap::set_bbmark_bit(int bci) {
457 _bb_hdr_bits.at_put(bci, true);
458 }
459
460 void GenerateOopMap::reachable_basicblock(GenerateOopMap *c, int bci, int *data) {
461 assert(bci>= 0 && bci < c->method()->code_size(), "index out of bounds");
462 BasicBlock* bb = c->get_basic_block_at(bci);
463 if (bb->is_dead()) {
464 bb->mark_as_alive();
465 *data = 1; // Mark basicblock as changed
466 }
467 }
468
469
470 void GenerateOopMap::mark_reachable_code() {
471 int change = 1; // int to get function pointers to work
472
473 // Mark entry basic block as alive and all exception handlers
474 _basic_blocks[0].mark_as_alive();
475 ExceptionTable excps(method());
476 for(int i = 0; i < excps.length(); i++) {
477 BasicBlock *bb = get_basic_block_at(excps.handler_pc(i));
478 // If block is not already alive (due to multiple exception handlers to same bb), then
479 // make it alive
480 if (bb->is_dead()) bb->mark_as_alive();
481 }
482
483 BytecodeStream bcs(_method);
484
485 // Iterate through all basic blocks until we reach a fixpoint
486 while (change) {
487 change = 0;
488
489 for (int i = 0; i < _bb_count; i++) {
490 BasicBlock *bb = &_basic_blocks[i];
491 if (bb->is_alive()) {
492 // Position bytecodestream at last bytecode in basicblock
493 bcs.set_start(bb->_end_bci);
494 bcs.next();
495 Bytecodes::Code bytecode = bcs.code();
496 int bci = bcs.bci();
497 assert(bci == bb->_end_bci, "wrong bci");
498
499 bool fell_through = jump_targets_do(&bcs, &GenerateOopMap::reachable_basicblock, &change);
500
501 // We will also mark successors of jsr's as alive.
502 switch (bytecode) {
503 case Bytecodes::_jsr:
504 case Bytecodes::_jsr_w:
505 assert(!fell_through, "should not happen");
506 reachable_basicblock(this, bci + Bytecodes::length_for(bytecode), &change);
507 break;
508 default:
509 break;
510 }
511 if (fell_through) {
512 // Mark successor as alive
513 if (bb[1].is_dead()) {
514 bb[1].mark_as_alive();
515 change = 1;
516 }
517 }
518 }
519 }
520 }
521 }
522
523 /* If the current instruction in "c" has no effect on control flow,
524 returns "true". Otherwise, calls "jmpFct" one or more times, with
525 "c", an appropriate "pcDelta", and "data" as arguments, then
526 returns "false". There is one exception: if the current
527 instruction is a "ret", returns "false" without calling "jmpFct".
528 Arrangements for tracking the control flow of a "ret" must be made
529 externally. */
530 bool GenerateOopMap::jump_targets_do(BytecodeStream *bcs, jmpFct_t jmpFct, int *data) {
531 int bci = bcs->bci();
532
533 switch (bcs->code()) {
534 case Bytecodes::_ifeq:
535 case Bytecodes::_ifne:
536 case Bytecodes::_iflt:
537 case Bytecodes::_ifge:
538 case Bytecodes::_ifgt:
539 case Bytecodes::_ifle:
540 case Bytecodes::_if_icmpeq:
541 case Bytecodes::_if_icmpne:
542 case Bytecodes::_if_icmplt:
543 case Bytecodes::_if_icmpge:
544 case Bytecodes::_if_icmpgt:
545 case Bytecodes::_if_icmple:
546 case Bytecodes::_if_acmpeq:
547 case Bytecodes::_if_acmpne:
548 case Bytecodes::_ifnull:
549 case Bytecodes::_ifnonnull:
550 (*jmpFct)(this, bcs->dest(), data);
551 // Class files verified by the old verifier can have a conditional branch
552 // as their last bytecode, provided the conditional branch is unreachable
553 // during execution. Check if this instruction is the method's last bytecode
554 // and, if so, don't call the jmpFct.
555 if (bci + 3 < method()->code_size()) {
556 (*jmpFct)(this, bci + 3, data);
557 }
558 break;
559
560 case Bytecodes::_goto:
561 (*jmpFct)(this, bcs->dest(), data);
562 break;
563 case Bytecodes::_goto_w:
564 (*jmpFct)(this, bcs->dest_w(), data);
565 break;
566 case Bytecodes::_tableswitch:
567 { Bytecode_tableswitch tableswitch(method(), bcs->bcp());
568 int len = tableswitch.length();
569
570 (*jmpFct)(this, bci + tableswitch.default_offset(), data); /* Default. jump address */
571 while (--len >= 0) {
572 (*jmpFct)(this, bci + tableswitch.dest_offset_at(len), data);
573 }
574 break;
575 }
576
577 case Bytecodes::_lookupswitch:
578 { Bytecode_lookupswitch lookupswitch(method(), bcs->bcp());
579 int npairs = lookupswitch.number_of_pairs();
580 (*jmpFct)(this, bci + lookupswitch.default_offset(), data); /* Default. */
581 while(--npairs >= 0) {
582 LookupswitchPair pair = lookupswitch.pair_at(npairs);
583 (*jmpFct)(this, bci + pair.offset(), data);
584 }
585 break;
586 }
587 case Bytecodes::_jsr:
588 assert(bcs->is_wide()==false, "sanity check");
589 (*jmpFct)(this, bcs->dest(), data);
590
591
592
593 break;
594 case Bytecodes::_jsr_w:
595 (*jmpFct)(this, bcs->dest_w(), data);
596 break;
597 case Bytecodes::_wide:
598 ShouldNotReachHere();
599 return true;
600 break;
601 case Bytecodes::_athrow:
602 case Bytecodes::_ireturn:
603 case Bytecodes::_lreturn:
604 case Bytecodes::_freturn:
605 case Bytecodes::_dreturn:
606 case Bytecodes::_areturn:
607 case Bytecodes::_return:
608 case Bytecodes::_ret:
609 break;
610 default:
611 return true;
612 }
613 return false;
614 }
615
616 /* Requires "pc" to be the head of a basic block; returns that basic
617 block. */
618 BasicBlock *GenerateOopMap::get_basic_block_at(int bci) const {
619 BasicBlock* bb = get_basic_block_containing(bci);
620 assert(bb->_bci == bci, "should have found BB");
621 return bb;
622 }
623
624 // Requires "pc" to be the start of an instruction; returns the basic
625 // block containing that instruction. */
626 BasicBlock *GenerateOopMap::get_basic_block_containing(int bci) const {
627 BasicBlock *bbs = _basic_blocks;
628 int lo = 0, hi = _bb_count - 1;
629
630 while (lo <= hi) {
631 int m = (lo + hi) / 2;
632 int mbci = bbs[m]._bci;
633 int nbci;
634
635 if ( m == _bb_count-1) {
636 assert( bci >= mbci && bci < method()->code_size(), "sanity check failed");
637 return bbs+m;
638 } else {
639 nbci = bbs[m+1]._bci;
640 }
641
642 if ( mbci <= bci && bci < nbci) {
643 return bbs+m;
644 } else if (mbci < bci) {
645 lo = m + 1;
646 } else {
647 assert(mbci > bci, "sanity check");
648 hi = m - 1;
649 }
650 }
651
652 fatal("should have found BB");
653 return NULL;
654 }
655
656 void GenerateOopMap::restore_state(BasicBlock *bb)
657 {
658 memcpy(_state, bb->_state, _state_len*sizeof(CellTypeState));
659 _stack_top = bb->_stack_top;
660 _monitor_top = bb->_monitor_top;
661 }
662
663 int GenerateOopMap::next_bb_start_pc(BasicBlock *bb) {
664 int bbNum = bb - _basic_blocks + 1;
665 if (bbNum == _bb_count)
666 return method()->code_size();
667
668 return _basic_blocks[bbNum]._bci;
669 }
670
671 //
672 // CellType handling methods
673 //
674
675 // Allocate memory and throw LinkageError if failure.
676 #define ALLOC_RESOURCE_ARRAY(var, type, count) \
677 var = NEW_RESOURCE_ARRAY_RETURN_NULL(type, count); \
678 if (var == NULL) { \
679 report_error("Cannot reserve enough memory to analyze this method"); \
680 return; \
681 }
682
683
684 void GenerateOopMap::init_state() {
685 _state_len = _max_locals + _max_stack + _max_monitors;
686 ALLOC_RESOURCE_ARRAY(_state, CellTypeState, _state_len);
687 memset(_state, 0, _state_len * sizeof(CellTypeState));
688 int count = MAX3(_max_locals, _max_stack, _max_monitors) + 1/*for null terminator char */;
689 ALLOC_RESOURCE_ARRAY(_state_vec_buf, char, count);
690 }
691
692 void GenerateOopMap::make_context_uninitialized() {
693 CellTypeState* vs = vars();
694
695 for (int i = 0; i < _max_locals; i++)
696 vs[i] = CellTypeState::uninit;
697
698 _stack_top = 0;
699 _monitor_top = 0;
700 }
701
702 int GenerateOopMap::methodsig_to_effect(Symbol* signature, bool is_static, CellTypeState* effect) {
703 ComputeEntryStack ces(signature);
704 return ces.compute_for_parameters(is_static, effect);
705 }
706
707 // Return result of merging cts1 and cts2.
708 CellTypeState CellTypeState::merge(CellTypeState cts, int slot) const {
709 CellTypeState result;
710
711 assert(!is_bottom() && !cts.is_bottom(),
712 "merge of bottom values is handled elsewhere");
713
714 result._state = _state | cts._state;
715
716 // If the top bit is set, we don't need to do any more work.
717 if (!result.is_info_top()) {
718 assert((result.can_be_address() || result.can_be_reference()),
719 "only addresses and references have non-top info");
720
721 if (!equal(cts)) {
722 // The two values being merged are different. Raise to top.
723 if (result.is_reference()) {
724 result = CellTypeState::make_slot_ref(slot);
725 } else {
726 result._state |= info_conflict;
727 }
728 }
729 }
730 assert(result.is_valid_state(), "checking that CTS merge maintains legal state");
731
732 return result;
733 }
734
735 // Merge the variable state for locals and stack from cts into bbts.
736 bool GenerateOopMap::merge_local_state_vectors(CellTypeState* cts,
737 CellTypeState* bbts) {
738 int i;
739 int len = _max_locals + _stack_top;
740 bool change = false;
741
742 for (i = len - 1; i >= 0; i--) {
743 CellTypeState v = cts[i].merge(bbts[i], i);
744 change = change || !v.equal(bbts[i]);
745 bbts[i] = v;
746 }
747
748 return change;
749 }
750
751 // Merge the monitor stack state from cts into bbts.
752 bool GenerateOopMap::merge_monitor_state_vectors(CellTypeState* cts,
753 CellTypeState* bbts) {
754 bool change = false;
755 if (_max_monitors > 0 && _monitor_top != bad_monitors) {
756 // If there are no monitors in the program, or there has been
757 // a monitor matching error before this point in the program,
758 // then we do not merge in the monitor state.
759
760 int base = _max_locals + _max_stack;
761 int len = base + _monitor_top;
762 for (int i = len - 1; i >= base; i--) {
763 CellTypeState v = cts[i].merge(bbts[i], i);
764
765 // Can we prove that, when there has been a change, it will already
766 // have been detected at this point? That would make this equal
767 // check here unnecessary.
768 change = change || !v.equal(bbts[i]);
769 bbts[i] = v;
770 }
771 }
772
773 return change;
774 }
775
776 void GenerateOopMap::copy_state(CellTypeState *dst, CellTypeState *src) {
777 int len = _max_locals + _stack_top;
778 for (int i = 0; i < len; i++) {
779 if (src[i].is_nonlock_reference()) {
780 dst[i] = CellTypeState::make_slot_ref(i);
781 } else {
782 dst[i] = src[i];
783 }
784 }
785 if (_max_monitors > 0 && _monitor_top != bad_monitors) {
786 int base = _max_locals + _max_stack;
787 len = base + _monitor_top;
788 for (int i = base; i < len; i++) {
789 dst[i] = src[i];
790 }
791 }
792 }
793
794
795 // Merge the states for the current block and the next. As long as a
796 // block is reachable the locals and stack must be merged. If the
797 // stack heights don't match then this is a verification error and
798 // it's impossible to interpret the code. Simultaneously monitor
799 // states are being check to see if they nest statically. If monitor
800 // depths match up then their states are merged. Otherwise the
801 // mismatch is simply recorded and interpretation continues since
802 // monitor matching is purely informational and doesn't say anything
803 // about the correctness of the code.
804 void GenerateOopMap::merge_state_into_bb(BasicBlock *bb) {
805 guarantee(bb != NULL, "null basicblock");
806 assert(bb->is_alive(), "merging state into a dead basicblock");
807
808 if (_stack_top == bb->_stack_top) {
809 // always merge local state even if monitors don't match.
810 if (merge_local_state_vectors(_state, bb->_state)) {
811 bb->set_changed(true);
812 }
813 if (_monitor_top == bb->_monitor_top) {
814 // monitors still match so continue merging monitor states.
815 if (merge_monitor_state_vectors(_state, bb->_state)) {
816 bb->set_changed(true);
817 }
818 } else {
819 if (log_is_enabled(Info, monitormismatch)) {
820 report_monitor_mismatch("monitor stack height merge conflict");
821 }
822 // When the monitor stacks are not matched, we set _monitor_top to
823 // bad_monitors. This signals that, from here on, the monitor stack cannot
824 // be trusted. In particular, monitorexit bytecodes may throw
825 // exceptions. We mark this block as changed so that the change
826 // propagates properly.
827 bb->_monitor_top = bad_monitors;
828 bb->set_changed(true);
829 _monitor_safe = false;
830 }
831 } else if (!bb->is_reachable()) {
832 // First time we look at this BB
833 copy_state(bb->_state, _state);
834 bb->_stack_top = _stack_top;
835 bb->_monitor_top = _monitor_top;
836 bb->set_changed(true);
837 } else {
838 verify_error("stack height conflict: %d vs. %d", _stack_top, bb->_stack_top);
839 }
840 }
841
842 void GenerateOopMap::merge_state(GenerateOopMap *gom, int bci, int* data) {
843 gom->merge_state_into_bb(gom->get_basic_block_at(bci));
844 }
845
846 void GenerateOopMap::set_var(int localNo, CellTypeState cts) {
847 assert(cts.is_reference() || cts.is_inline_type() || cts.is_address(),
848 "wrong celltypestate");
849 if (localNo < 0 || localNo > _max_locals) {
850 verify_error("variable write error: r%d", localNo);
851 return;
852 }
853 vars()[localNo] = cts;
854 }
855
856 CellTypeState GenerateOopMap::get_var(int localNo) {
857 assert(localNo < _max_locals + _nof_refval_conflicts, "variable read error");
858 if (localNo < 0 || localNo > _max_locals) {
859 verify_error("variable read error: r%d", localNo);
860 return valCTS; // just to pick something;
861 }
862 return vars()[localNo];
863 }
864
865 CellTypeState GenerateOopMap::pop() {
866 if ( _stack_top <= 0) {
867 verify_error("stack underflow");
868 return valCTS; // just to pick something
869 }
870 return stack()[--_stack_top];
871 }
872
873 void GenerateOopMap::push(CellTypeState cts) {
874 if ( _stack_top >= _max_stack) {
875 verify_error("stack overflow");
876 return;
877 }
878 stack()[_stack_top++] = cts;
879 }
880
881 CellTypeState GenerateOopMap::monitor_pop() {
882 assert(_monitor_top != bad_monitors, "monitor_pop called on error monitor stack");
883 if (_monitor_top == 0) {
884 // We have detected a pop of an empty monitor stack.
885 _monitor_safe = false;
886 _monitor_top = bad_monitors;
887
888 if (log_is_enabled(Info, monitormismatch)) {
889 report_monitor_mismatch("monitor stack underflow");
890 }
891 return CellTypeState::ref; // just to keep the analysis going.
892 }
893 return monitors()[--_monitor_top];
894 }
895
896 void GenerateOopMap::monitor_push(CellTypeState cts) {
897 assert(_monitor_top != bad_monitors, "monitor_push called on error monitor stack");
898 if (_monitor_top >= _max_monitors) {
899 // Some monitorenter is being executed more than once.
900 // This means that the monitor stack cannot be simulated.
901 _monitor_safe = false;
902 _monitor_top = bad_monitors;
903
904 if (log_is_enabled(Info, monitormismatch)) {
905 report_monitor_mismatch("monitor stack overflow");
906 }
907 return;
908 }
909 monitors()[_monitor_top++] = cts;
910 }
911
912 //
913 // Interpretation handling methods
914 //
915
916 void GenerateOopMap::do_interpretation()
917 {
918 // "i" is just for debugging, so we can detect cases where this loop is
919 // iterated more than once.
920 int i = 0;
921 do {
922 #ifndef PRODUCT
923 if (TraceNewOopMapGeneration) {
924 tty->print("\n\nIteration #%d of do_interpretation loop, method:\n", i);
925 method()->print_name(tty);
926 tty->print("\n\n");
927 }
928 #endif
929 _conflict = false;
930 _monitor_safe = true;
931 // init_state is now called from init_basic_blocks. The length of a
932 // state vector cannot be determined until we have made a pass through
933 // the bytecodes counting the possible monitor entries.
934 if (!_got_error) init_basic_blocks();
935 if (!_got_error) setup_method_entry_state();
936 if (!_got_error) interp_all();
937 if (!_got_error) rewrite_refval_conflicts();
938 i++;
939 } while (_conflict && !_got_error);
940 }
941
942 void GenerateOopMap::init_basic_blocks() {
943 // Note: Could consider reserving only the needed space for each BB's state
944 // (entry stack may not be of maximal height for every basic block).
945 // But cumbersome since we don't know the stack heights yet. (Nor the
946 // monitor stack heights...)
947
948 ALLOC_RESOURCE_ARRAY(_basic_blocks, BasicBlock, _bb_count);
949
950 // Make a pass through the bytecodes. Count the number of monitorenters.
951 // This can be used an upper bound on the monitor stack depth in programs
952 // which obey stack discipline with their monitor usage. Initialize the
953 // known information about basic blocks.
954 BytecodeStream j(_method);
955 Bytecodes::Code bytecode;
956
957 int bbNo = 0;
958 int monitor_count = 0;
959 int prev_bci = -1;
960 while( (bytecode = j.next()) >= 0) {
961 if (j.code() == Bytecodes::_monitorenter) {
962 monitor_count++;
963 }
964
965 int bci = j.bci();
966 if (is_bb_header(bci)) {
967 // Initialize the basicblock structure
968 BasicBlock *bb = _basic_blocks + bbNo;
969 bb->_bci = bci;
970 bb->_max_locals = _max_locals;
971 bb->_max_stack = _max_stack;
972 bb->set_changed(false);
973 bb->_stack_top = BasicBlock::_dead_basic_block; // Initialize all basicblocks are dead.
974 bb->_monitor_top = bad_monitors;
975
976 if (bbNo > 0) {
977 _basic_blocks[bbNo - 1]._end_bci = prev_bci;
978 }
979
980 bbNo++;
981 }
982 // Remember previous bci.
983 prev_bci = bci;
984 }
985 // Set
986 _basic_blocks[bbNo-1]._end_bci = prev_bci;
987
988
989 // Check that the correct number of basicblocks was found
990 if (bbNo !=_bb_count) {
991 if (bbNo < _bb_count) {
992 verify_error("jump into the middle of instruction?");
993 return;
994 } else {
995 verify_error("extra basic blocks - should not happen?");
996 return;
997 }
998 }
999
1000 _max_monitors = monitor_count;
1001
1002 // Now that we have a bound on the depth of the monitor stack, we can
1003 // initialize the CellTypeState-related information.
1004 init_state();
1005
1006 // We allocate space for all state-vectors for all basicblocks in one huge
1007 // chunk. Then in the next part of the code, we set a pointer in each
1008 // _basic_block that points to each piece.
1009
1010 // The product of bbNo and _state_len can get large if there are lots of
1011 // basic blocks and stack/locals/monitors. Need to check to make sure
1012 // we don't overflow the capacity of a pointer.
1013 if ((unsigned)bbNo > UINTPTR_MAX / sizeof(CellTypeState) / _state_len) {
1014 report_error("The amount of memory required to analyze this method "
1015 "exceeds addressable range");
1016 return;
1017 }
1018
1019 CellTypeState *basicBlockState;
1020 ALLOC_RESOURCE_ARRAY(basicBlockState, CellTypeState, bbNo * _state_len);
1021 memset(basicBlockState, 0, bbNo * _state_len * sizeof(CellTypeState));
1022
1023 // Make a pass over the basicblocks and assign their state vectors.
1024 for (int blockNum=0; blockNum < bbNo; blockNum++) {
1025 BasicBlock *bb = _basic_blocks + blockNum;
1026 bb->_state = basicBlockState + blockNum * _state_len;
1027
1028 #ifdef ASSERT
1029 if (blockNum + 1 < bbNo) {
1030 address bcp = _method->bcp_from(bb->_end_bci);
1031 int bc_len = Bytecodes::java_length_at(_method(), bcp);
1032 assert(bb->_end_bci + bc_len == bb[1]._bci, "unmatched bci info in basicblock");
1033 }
1034 #endif
1035 }
1036 #ifdef ASSERT
1037 { BasicBlock *bb = &_basic_blocks[bbNo-1];
1038 address bcp = _method->bcp_from(bb->_end_bci);
1039 int bc_len = Bytecodes::java_length_at(_method(), bcp);
1040 assert(bb->_end_bci + bc_len == _method->code_size(), "wrong end bci");
1041 }
1042 #endif
1043
1044 // Mark all alive blocks
1045 mark_reachable_code();
1046 }
1047
1048 void GenerateOopMap::setup_method_entry_state() {
1049
1050 // Initialize all locals to 'uninit' and set stack-height to 0
1051 make_context_uninitialized();
1052
1053 // Initialize CellState type of arguments
1054 methodsig_to_effect(method()->signature(), method()->is_static(), vars());
1055
1056 // If some references must be pre-assigned to null, then set that up
1057 initialize_vars();
1058
1059 // This is the start state
1060 merge_state_into_bb(&_basic_blocks[0]);
1061
1062 assert(_basic_blocks[0].changed(), "we are not getting off the ground");
1063 }
1064
1065 // The instruction at bci is changing size by "delta". Update the basic blocks.
1066 void GenerateOopMap::update_basic_blocks(int bci, int delta,
1067 int new_method_size) {
1068 assert(new_method_size >= method()->code_size() + delta,
1069 "new method size is too small");
1070
1071 _bb_hdr_bits.reinitialize(new_method_size);
1072
1073 for(int k = 0; k < _bb_count; k++) {
1074 if (_basic_blocks[k]._bci > bci) {
1075 _basic_blocks[k]._bci += delta;
1076 _basic_blocks[k]._end_bci += delta;
1077 }
1078 _bb_hdr_bits.at_put(_basic_blocks[k]._bci, true);
1079 }
1080 }
1081
1082 //
1083 // Initvars handling
1084 //
1085
1086 void GenerateOopMap::initialize_vars() {
1087 for (int k = 0; k < _init_vars->length(); k++)
1088 _state[_init_vars->at(k)] = CellTypeState::make_slot_ref(k);
1089 }
1090
1091 void GenerateOopMap::add_to_ref_init_set(int localNo) {
1092
1093 if (TraceNewOopMapGeneration)
1094 tty->print_cr("Added init vars: %d", localNo);
1095
1096 // Is it already in the set?
1097 if (_init_vars->contains(localNo) )
1098 return;
1099
1100 _init_vars->append(localNo);
1101 }
1102
1103 //
1104 // Interpreration code
1105 //
1106
1107 void GenerateOopMap::interp_all() {
1108 bool change = true;
1109
1110 while (change && !_got_error) {
1111 change = false;
1112 for (int i = 0; i < _bb_count && !_got_error; i++) {
1113 BasicBlock *bb = &_basic_blocks[i];
1114 if (bb->changed()) {
1115 if (_got_error) return;
1116 change = true;
1117 bb->set_changed(false);
1118 interp_bb(bb);
1119 }
1120 }
1121 }
1122 }
1123
1124 void GenerateOopMap::interp_bb(BasicBlock *bb) {
1125
1126 // We do not want to do anything in case the basic-block has not been initialized. This
1127 // will happen in the case where there is dead-code hang around in a method.
1128 assert(bb->is_reachable(), "should be reachable or deadcode exist");
1129 restore_state(bb);
1130
1131 BytecodeStream itr(_method);
1132
1133 // Set iterator interval to be the current basicblock
1134 int lim_bci = next_bb_start_pc(bb);
1135 itr.set_interval(bb->_bci, lim_bci);
1136 assert(lim_bci != bb->_bci, "must be at least one instruction in a basicblock");
1137 itr.next(); // read first instruction
1138
1139 // Iterates through all bytecodes except the last in a basic block.
1140 // We handle the last one special, since there is controlflow change.
1141 while(itr.next_bci() < lim_bci && !_got_error) {
1142 if (_has_exceptions || _monitor_top != 0) {
1143 // We do not need to interpret the results of exceptional
1144 // continuation from this instruction when the method has no
1145 // exception handlers and the monitor stack is currently
1146 // empty.
1147 do_exception_edge(&itr);
1148 }
1149 interp1(&itr);
1150 itr.next();
1151 }
1152
1153 // Handle last instruction.
1154 if (!_got_error) {
1155 assert(itr.next_bci() == lim_bci, "must point to end");
1156 if (_has_exceptions || _monitor_top != 0) {
1157 do_exception_edge(&itr);
1158 }
1159 interp1(&itr);
1160
1161 bool fall_through = jump_targets_do(&itr, GenerateOopMap::merge_state, NULL);
1162 if (_got_error) return;
1163
1164 if (itr.code() == Bytecodes::_ret) {
1165 assert(!fall_through, "cannot be set if ret instruction");
1166 // Automatically handles 'wide' ret indices
1167 ret_jump_targets_do(&itr, GenerateOopMap::merge_state, itr.get_index(), NULL);
1168 } else if (fall_through) {
1169 // Hit end of BB, but the instr. was a fall-through instruction,
1170 // so perform transition as if the BB ended in a "jump".
1171 if (lim_bci != bb[1]._bci) {
1172 verify_error("bytecodes fell through last instruction");
1173 return;
1174 }
1175 merge_state_into_bb(bb + 1);
1176 }
1177 }
1178 }
1179
1180 void GenerateOopMap::do_exception_edge(BytecodeStream* itr) {
1181 // Only check exception edge, if bytecode can trap
1182 if (!Bytecodes::can_trap(itr->code())) return;
1183 switch (itr->code()) {
1184 case Bytecodes::_aload_0:
1185 // These bytecodes can trap for rewriting. We need to assume that
1186 // they do not throw exceptions to make the monitor analysis work.
1187 return;
1188
1189 case Bytecodes::_ireturn:
1190 case Bytecodes::_lreturn:
1191 case Bytecodes::_freturn:
1192 case Bytecodes::_dreturn:
1193 case Bytecodes::_areturn:
1194 case Bytecodes::_return:
1195 // If the monitor stack height is not zero when we leave the method,
1196 // then we are either exiting with a non-empty stack or we have
1197 // found monitor trouble earlier in our analysis. In either case,
1198 // assume an exception could be taken here.
1199 if (_monitor_top == 0) {
1200 return;
1201 }
1202 break;
1203
1204 case Bytecodes::_monitorexit:
1205 // If the monitor stack height is bad_monitors, then we have detected a
1206 // monitor matching problem earlier in the analysis. If the
1207 // monitor stack height is 0, we are about to pop a monitor
1208 // off of an empty stack. In either case, the bytecode
1209 // could throw an exception.
1210 if (_monitor_top != bad_monitors && _monitor_top != 0) {
1211 return;
1212 }
1213 break;
1214
1215 default:
1216 break;
1217 }
1218
1219 if (_has_exceptions) {
1220 int bci = itr->bci();
1221 ExceptionTable exct(method());
1222 for(int i = 0; i< exct.length(); i++) {
1223 int start_pc = exct.start_pc(i);
1224 int end_pc = exct.end_pc(i);
1225 int handler_pc = exct.handler_pc(i);
1226 int catch_type = exct.catch_type_index(i);
1227
1228 if (start_pc <= bci && bci < end_pc) {
1229 BasicBlock *excBB = get_basic_block_at(handler_pc);
1230 guarantee(excBB != NULL, "no basic block for exception");
1231 CellTypeState *excStk = excBB->stack();
1232 CellTypeState *cOpStck = stack();
1233 CellTypeState cOpStck_0 = cOpStck[0];
1234 int cOpStackTop = _stack_top;
1235
1236 // Exception stacks are always the same.
1237 assert(method()->max_stack() > 0, "sanity check");
1238
1239 // We remembered the size and first element of "cOpStck"
1240 // above; now we temporarily set them to the appropriate
1241 // values for an exception handler. */
1242 cOpStck[0] = CellTypeState::make_slot_ref(_max_locals);
1243 _stack_top = 1;
1244
1245 merge_state_into_bb(excBB);
1246
1247 // Now undo the temporary change.
1248 cOpStck[0] = cOpStck_0;
1249 _stack_top = cOpStackTop;
1250
1251 // If this is a "catch all" handler, then we do not need to
1252 // consider any additional handlers.
1253 if (catch_type == 0) {
1254 return;
1255 }
1256 }
1257 }
1258 }
1259
1260 // It is possible that none of the exception handlers would have caught
1261 // the exception. In this case, we will exit the method. We must
1262 // ensure that the monitor stack is empty in this case.
1263 if (_monitor_top == 0) {
1264 return;
1265 }
1266
1267 // We pessimistically assume that this exception can escape the
1268 // method. (It is possible that it will always be caught, but
1269 // we don't care to analyse the types of the catch clauses.)
1270
1271 // We don't set _monitor_top to bad_monitors because there are no successors
1272 // to this exceptional exit.
1273
1274 if (log_is_enabled(Info, monitormismatch) && _monitor_safe) {
1275 // We check _monitor_safe so that we only report the first mismatched
1276 // exceptional exit.
1277 report_monitor_mismatch("non-empty monitor stack at exceptional exit");
1278 }
1279 _monitor_safe = false;
1280
1281 }
1282
1283 void GenerateOopMap::report_monitor_mismatch(const char *msg) {
1284 ResourceMark rm;
1285 LogStream ls(Log(monitormismatch)::info());
1286 ls.print("Monitor mismatch in method ");
1287 method()->print_short_name(&ls);
1288 ls.print_cr(": %s", msg);
1289 }
1290
1291 void GenerateOopMap::print_states(outputStream *os,
1292 CellTypeState* vec, int num) {
1293 for (int i = 0; i < num; i++) {
1294 vec[i].print(tty);
1295 }
1296 }
1297
1298 // Print the state values at the current bytecode.
1299 void GenerateOopMap::print_current_state(outputStream *os,
1300 BytecodeStream *currentBC,
1301 bool detailed) {
1302 if (detailed) {
1303 os->print(" %4d vars = ", currentBC->bci());
1304 print_states(os, vars(), _max_locals);
1305 os->print(" %s", Bytecodes::name(currentBC->code()));
1306 } else {
1307 os->print(" %4d vars = '%s' ", currentBC->bci(), state_vec_to_string(vars(), _max_locals));
1308 os->print(" stack = '%s' ", state_vec_to_string(stack(), _stack_top));
1309 if (_monitor_top != bad_monitors) {
1310 os->print(" monitors = '%s' \t%s", state_vec_to_string(monitors(), _monitor_top), Bytecodes::name(currentBC->code()));
1311 } else {
1312 os->print(" [bad monitor stack]");
1313 }
1314 }
1315
1316 switch(currentBC->code()) {
1317 case Bytecodes::_invokevirtual:
1318 case Bytecodes::_invokespecial:
1319 case Bytecodes::_invokestatic:
1320 case Bytecodes::_invokedynamic:
1321 case Bytecodes::_invokeinterface: {
1322 int idx = currentBC->has_index_u4() ? currentBC->get_index_u4() : currentBC->get_index_u2_cpcache();
1323 ConstantPool* cp = method()->constants();
1324 int nameAndTypeIdx = cp->name_and_type_ref_index_at(idx);
1325 int signatureIdx = cp->signature_ref_index_at(nameAndTypeIdx);
1326 Symbol* signature = cp->symbol_at(signatureIdx);
1327 os->print("%s", signature->as_C_string());
1328 }
1329 default:
1330 break;
1331 }
1332
1333 if (detailed) {
1334 os->cr();
1335 os->print(" stack = ");
1336 print_states(os, stack(), _stack_top);
1337 os->cr();
1338 if (_monitor_top != bad_monitors) {
1339 os->print(" monitors = ");
1340 print_states(os, monitors(), _monitor_top);
1341 } else {
1342 os->print(" [bad monitor stack]");
1343 }
1344 }
1345
1346 os->cr();
1347 }
1348
1349 // Sets the current state to be the state after executing the
1350 // current instruction, starting in the current state.
1351 void GenerateOopMap::interp1(BytecodeStream *itr) {
1352 if (TraceNewOopMapGeneration) {
1353 print_current_state(tty, itr, TraceNewOopMapGenerationDetailed);
1354 }
1355
1356 // Should we report the results? Result is reported *before* the instruction at the current bci is executed.
1357 // However, not for calls. For calls we do not want to include the arguments, so we postpone the reporting until
1358 // they have been popped (in method ppl).
1359 if (_report_result == true) {
1360 switch(itr->code()) {
1361 case Bytecodes::_invokevirtual:
1362 case Bytecodes::_invokespecial:
1363 case Bytecodes::_invokestatic:
1364 case Bytecodes::_invokedynamic:
1365 case Bytecodes::_invokeinterface:
1366 _itr_send = itr;
1367 _report_result_for_send = true;
1368 break;
1369 default:
1370 fill_stackmap_for_opcodes(itr, vars(), stack(), _stack_top);
1371 break;
1372 }
1373 }
1374
1375 // abstract interpretation of current opcode
1376 switch(itr->code()) {
1377 case Bytecodes::_nop: break;
1378 case Bytecodes::_goto: break;
1379 case Bytecodes::_goto_w: break;
1380 case Bytecodes::_iinc: break;
1381 case Bytecodes::_return: do_return_monitor_check();
1382 break;
1383
1384 case Bytecodes::_aconst_null:
1385 case Bytecodes::_new: ppush1(CellTypeState::make_line_ref(itr->bci()));
1386 break;
1387
1388 case Bytecodes::_aconst_init: ppush1(CellTypeState::make_line_ref(itr->bci())); break;
1389 case Bytecodes::_withfield: do_withfield(itr->get_index_u2_cpcache(), itr->bci()); break;
1390
1391 case Bytecodes::_iconst_m1:
1392 case Bytecodes::_iconst_0:
1393 case Bytecodes::_iconst_1:
1394 case Bytecodes::_iconst_2:
1395 case Bytecodes::_iconst_3:
1396 case Bytecodes::_iconst_4:
1397 case Bytecodes::_iconst_5:
1398 case Bytecodes::_fconst_0:
1399 case Bytecodes::_fconst_1:
1400 case Bytecodes::_fconst_2:
1401 case Bytecodes::_bipush:
1402 case Bytecodes::_sipush: ppush1(valCTS); break;
1403
1404 case Bytecodes::_lconst_0:
1405 case Bytecodes::_lconst_1:
1406 case Bytecodes::_dconst_0:
1407 case Bytecodes::_dconst_1: ppush(vvCTS); break;
1408
1409 case Bytecodes::_ldc2_w: ppush(vvCTS); break;
1410
1411 case Bytecodes::_ldc: // fall through:
1412 case Bytecodes::_ldc_w: do_ldc(itr->bci()); break;
1413
1414 case Bytecodes::_iload:
1415 case Bytecodes::_fload: ppload(vCTS, itr->get_index()); break;
1416
1417 case Bytecodes::_lload:
1418 case Bytecodes::_dload: ppload(vvCTS,itr->get_index()); break;
1419
1420 case Bytecodes::_aload: ppload(rCTS, itr->get_index()); break;
1421
1422 case Bytecodes::_iload_0:
1423 case Bytecodes::_fload_0: ppload(vCTS, 0); break;
1424 case Bytecodes::_iload_1:
1425 case Bytecodes::_fload_1: ppload(vCTS, 1); break;
1426 case Bytecodes::_iload_2:
1427 case Bytecodes::_fload_2: ppload(vCTS, 2); break;
1428 case Bytecodes::_iload_3:
1429 case Bytecodes::_fload_3: ppload(vCTS, 3); break;
1430
1431 case Bytecodes::_lload_0:
1432 case Bytecodes::_dload_0: ppload(vvCTS, 0); break;
1433 case Bytecodes::_lload_1:
1434 case Bytecodes::_dload_1: ppload(vvCTS, 1); break;
1435 case Bytecodes::_lload_2:
1436 case Bytecodes::_dload_2: ppload(vvCTS, 2); break;
1437 case Bytecodes::_lload_3:
1438 case Bytecodes::_dload_3: ppload(vvCTS, 3); break;
1439
1440 case Bytecodes::_aload_0: ppload(rCTS, 0); break;
1441 case Bytecodes::_aload_1: ppload(rCTS, 1); break;
1442 case Bytecodes::_aload_2: ppload(rCTS, 2); break;
1443 case Bytecodes::_aload_3: ppload(rCTS, 3); break;
1444
1445 case Bytecodes::_iaload:
1446 case Bytecodes::_faload:
1447 case Bytecodes::_baload:
1448 case Bytecodes::_caload:
1449 case Bytecodes::_saload: pp(vrCTS, vCTS); break;
1450
1451 case Bytecodes::_laload: pp(vrCTS, vvCTS); break;
1452 case Bytecodes::_daload: pp(vrCTS, vvCTS); break;
1453
1454 case Bytecodes::_aaload: pp_new_ref(vrCTS, itr->bci()); break;
1455
1456 case Bytecodes::_istore:
1457 case Bytecodes::_fstore: ppstore(vCTS, itr->get_index()); break;
1458
1459 case Bytecodes::_lstore:
1460 case Bytecodes::_dstore: ppstore(vvCTS, itr->get_index()); break;
1461
1462 case Bytecodes::_astore: do_astore(itr->get_index()); break;
1463
1464 case Bytecodes::_istore_0:
1465 case Bytecodes::_fstore_0: ppstore(vCTS, 0); break;
1466 case Bytecodes::_istore_1:
1467 case Bytecodes::_fstore_1: ppstore(vCTS, 1); break;
1468 case Bytecodes::_istore_2:
1469 case Bytecodes::_fstore_2: ppstore(vCTS, 2); break;
1470 case Bytecodes::_istore_3:
1471 case Bytecodes::_fstore_3: ppstore(vCTS, 3); break;
1472
1473 case Bytecodes::_lstore_0:
1474 case Bytecodes::_dstore_0: ppstore(vvCTS, 0); break;
1475 case Bytecodes::_lstore_1:
1476 case Bytecodes::_dstore_1: ppstore(vvCTS, 1); break;
1477 case Bytecodes::_lstore_2:
1478 case Bytecodes::_dstore_2: ppstore(vvCTS, 2); break;
1479 case Bytecodes::_lstore_3:
1480 case Bytecodes::_dstore_3: ppstore(vvCTS, 3); break;
1481
1482 case Bytecodes::_astore_0: do_astore(0); break;
1483 case Bytecodes::_astore_1: do_astore(1); break;
1484 case Bytecodes::_astore_2: do_astore(2); break;
1485 case Bytecodes::_astore_3: do_astore(3); break;
1486
1487 case Bytecodes::_iastore:
1488 case Bytecodes::_fastore:
1489 case Bytecodes::_bastore:
1490 case Bytecodes::_castore:
1491 case Bytecodes::_sastore: ppop(vvrCTS); break;
1492 case Bytecodes::_lastore:
1493 case Bytecodes::_dastore: ppop(vvvrCTS); break;
1494 case Bytecodes::_aastore: ppop(rvrCTS); break;
1495
1496 case Bytecodes::_pop: ppop_any(1); break;
1497 case Bytecodes::_pop2: ppop_any(2); break;
1498
1499 case Bytecodes::_dup: ppdupswap(1, "11"); break;
1500 case Bytecodes::_dup_x1: ppdupswap(2, "121"); break;
1501 case Bytecodes::_dup_x2: ppdupswap(3, "1321"); break;
1502 case Bytecodes::_dup2: ppdupswap(2, "2121"); break;
1503 case Bytecodes::_dup2_x1: ppdupswap(3, "21321"); break;
1504 case Bytecodes::_dup2_x2: ppdupswap(4, "214321"); break;
1505 case Bytecodes::_swap: ppdupswap(2, "12"); break;
1506
1507 case Bytecodes::_iadd:
1508 case Bytecodes::_fadd:
1509 case Bytecodes::_isub:
1510 case Bytecodes::_fsub:
1511 case Bytecodes::_imul:
1512 case Bytecodes::_fmul:
1513 case Bytecodes::_idiv:
1514 case Bytecodes::_fdiv:
1515 case Bytecodes::_irem:
1516 case Bytecodes::_frem:
1517 case Bytecodes::_ishl:
1518 case Bytecodes::_ishr:
1519 case Bytecodes::_iushr:
1520 case Bytecodes::_iand:
1521 case Bytecodes::_ior:
1522 case Bytecodes::_ixor:
1523 case Bytecodes::_l2f:
1524 case Bytecodes::_l2i:
1525 case Bytecodes::_d2f:
1526 case Bytecodes::_d2i:
1527 case Bytecodes::_fcmpl:
1528 case Bytecodes::_fcmpg: pp(vvCTS, vCTS); break;
1529
1530 case Bytecodes::_ladd:
1531 case Bytecodes::_dadd:
1532 case Bytecodes::_lsub:
1533 case Bytecodes::_dsub:
1534 case Bytecodes::_lmul:
1535 case Bytecodes::_dmul:
1536 case Bytecodes::_ldiv:
1537 case Bytecodes::_ddiv:
1538 case Bytecodes::_lrem:
1539 case Bytecodes::_drem:
1540 case Bytecodes::_land:
1541 case Bytecodes::_lor:
1542 case Bytecodes::_lxor: pp(vvvvCTS, vvCTS); break;
1543
1544 case Bytecodes::_ineg:
1545 case Bytecodes::_fneg:
1546 case Bytecodes::_i2f:
1547 case Bytecodes::_f2i:
1548 case Bytecodes::_i2c:
1549 case Bytecodes::_i2s:
1550 case Bytecodes::_i2b: pp(vCTS, vCTS); break;
1551
1552 case Bytecodes::_lneg:
1553 case Bytecodes::_dneg:
1554 case Bytecodes::_l2d:
1555 case Bytecodes::_d2l: pp(vvCTS, vvCTS); break;
1556
1557 case Bytecodes::_lshl:
1558 case Bytecodes::_lshr:
1559 case Bytecodes::_lushr: pp(vvvCTS, vvCTS); break;
1560
1561 case Bytecodes::_i2l:
1562 case Bytecodes::_i2d:
1563 case Bytecodes::_f2l:
1564 case Bytecodes::_f2d: pp(vCTS, vvCTS); break;
1565
1566 case Bytecodes::_lcmp: pp(vvvvCTS, vCTS); break;
1567 case Bytecodes::_dcmpl:
1568 case Bytecodes::_dcmpg: pp(vvvvCTS, vCTS); break;
1569
1570 case Bytecodes::_ifeq:
1571 case Bytecodes::_ifne:
1572 case Bytecodes::_iflt:
1573 case Bytecodes::_ifge:
1574 case Bytecodes::_ifgt:
1575 case Bytecodes::_ifle:
1576 case Bytecodes::_tableswitch: ppop1(valCTS);
1577 break;
1578 case Bytecodes::_ireturn:
1579 case Bytecodes::_freturn: do_return_monitor_check();
1580 ppop1(valCTS);
1581 break;
1582 case Bytecodes::_if_icmpeq:
1583 case Bytecodes::_if_icmpne:
1584 case Bytecodes::_if_icmplt:
1585 case Bytecodes::_if_icmpge:
1586 case Bytecodes::_if_icmpgt:
1587 case Bytecodes::_if_icmple: ppop(vvCTS);
1588 break;
1589
1590 case Bytecodes::_lreturn: do_return_monitor_check();
1591 ppop(vvCTS);
1592 break;
1593
1594 case Bytecodes::_dreturn: do_return_monitor_check();
1595 ppop(vvCTS);
1596 break;
1597
1598 case Bytecodes::_if_acmpeq:
1599 case Bytecodes::_if_acmpne: ppop(rrCTS); break;
1600
1601 case Bytecodes::_jsr: do_jsr(itr->dest()); break;
1602 case Bytecodes::_jsr_w: do_jsr(itr->dest_w()); break;
1603
1604 case Bytecodes::_getstatic: do_field(true, true, itr->get_index_u2_cpcache(), itr->bci()); break;
1605 case Bytecodes::_putstatic: do_field(false, true, itr->get_index_u2_cpcache(), itr->bci()); break;
1606 case Bytecodes::_getfield: do_field(true, false, itr->get_index_u2_cpcache(), itr->bci()); break;
1607 case Bytecodes::_putfield: do_field(false, false, itr->get_index_u2_cpcache(), itr->bci()); break;
1608
1609 case Bytecodes::_invokeinterface:
1610 case Bytecodes::_invokevirtual:
1611 case Bytecodes::_invokespecial: do_method(false, itr->get_index_u2_cpcache(), itr->bci()); break;
1612 case Bytecodes::_invokestatic: do_method(true , itr->get_index_u2_cpcache(), itr->bci()); break;
1613 case Bytecodes::_invokedynamic: do_method(true , itr->get_index_u4(), itr->bci()); break;
1614 case Bytecodes::_newarray:
1615 case Bytecodes::_anewarray: pp_new_ref(vCTS, itr->bci()); break;
1616 case Bytecodes::_checkcast: do_checkcast(); break;
1617 case Bytecodes::_arraylength:
1618 case Bytecodes::_instanceof: pp(rCTS, vCTS); break;
1619 case Bytecodes::_monitorenter: do_monitorenter(itr->bci()); break;
1620 case Bytecodes::_monitorexit: do_monitorexit(itr->bci()); break;
1621
1622 case Bytecodes::_athrow: // handled by do_exception_edge() BUT ...
1623 // vlh(apple): do_exception_edge() does not get
1624 // called if method has no exception handlers
1625 if ((!_has_exceptions) && (_monitor_top > 0)) {
1626 _monitor_safe = false;
1627 }
1628 break;
1629
1630 case Bytecodes::_areturn: do_return_monitor_check();
1631 ppop1(refCTS);
1632 break;
1633
1634 case Bytecodes::_ifnull:
1635 case Bytecodes::_ifnonnull: ppop1(refCTS); break;
1636 case Bytecodes::_multianewarray: do_multianewarray(*(itr->bcp()+3), itr->bci()); break;
1637
1638 case Bytecodes::_wide: fatal("Iterator should skip this bytecode"); break;
1639 case Bytecodes::_ret: break;
1640
1641 // Java opcodes
1642 case Bytecodes::_lookupswitch: ppop1(valCTS); break;
1643
1644 default:
1645 tty->print("unexpected opcode: %d\n", itr->code());
1646 ShouldNotReachHere();
1647 break;
1648 }
1649 }
1650
1651 void GenerateOopMap::check_type(CellTypeState expected, CellTypeState actual) {
1652 if (!expected.equal_kind(actual)) {
1653 verify_error("wrong type on stack (found: %c expected: %c)", actual.to_char(), expected.to_char());
1654 }
1655 }
1656
1657 void GenerateOopMap::ppstore(CellTypeState *in, int loc_no) {
1658 while(!(*in).is_bottom()) {
1659 CellTypeState expected =*in++;
1660 CellTypeState actual = pop();
1661 check_type(expected, actual);
1662 assert(loc_no >= 0, "sanity check");
1663 set_var(loc_no++, actual);
1664 }
1665 }
1666
1667 void GenerateOopMap::ppload(CellTypeState *out, int loc_no) {
1668 while(!(*out).is_bottom()) {
1669 CellTypeState out1 = *out++;
1670 CellTypeState vcts = get_var(loc_no);
1671 assert(out1.can_be_reference() || out1.can_be_value(),
1672 "can only load refs. and values.");
1673 if (out1.is_reference()) {
1674 assert(loc_no>=0, "sanity check");
1675 if (!vcts.is_reference()) {
1676 // We were asked to push a reference, but the type of the
1677 // variable can be something else
1678 _conflict = true;
1679 if (vcts.can_be_uninit()) {
1680 // It is a ref-uninit conflict (at least). If there are other
1681 // problems, we'll get them in the next round
1682 add_to_ref_init_set(loc_no);
1683 vcts = out1;
1684 } else {
1685 // It wasn't a ref-uninit conflict. So must be a
1686 // ref-val or ref-pc conflict. Split the variable.
1687 record_refval_conflict(loc_no);
1688 vcts = out1;
1689 }
1690 push(out1); // recover...
1691 } else {
1692 push(vcts); // preserve reference.
1693 }
1694 // Otherwise it is a conflict, but one that verification would
1695 // have caught if illegal. In particular, it can't be a topCTS
1696 // resulting from mergeing two difference pcCTS's since the verifier
1697 // would have rejected any use of such a merge.
1698 } else {
1699 push(out1); // handle val/init conflict
1700 }
1701 loc_no++;
1702 }
1703 }
1704
1705 void GenerateOopMap::ppdupswap(int poplen, const char *out) {
1706 CellTypeState actual[5];
1707 assert(poplen < 5, "this must be less than length of actual vector");
1708
1709 // Pop all arguments.
1710 for (int i = 0; i < poplen; i++) {
1711 actual[i] = pop();
1712 }
1713 // Field _state is uninitialized when calling push.
1714 for (int i = poplen; i < 5; i++) {
1715 actual[i] = CellTypeState::uninit;
1716 }
1717
1718 // put them back
1719 char push_ch = *out++;
1720 while (push_ch != '\0') {
1721 int idx = push_ch - '1';
1722 assert(idx >= 0 && idx < poplen, "wrong arguments");
1723 push(actual[idx]);
1724 push_ch = *out++;
1725 }
1726 }
1727
1728 void GenerateOopMap::ppop1(CellTypeState out) {
1729 CellTypeState actual = pop();
1730 check_type(out, actual);
1731 }
1732
1733 void GenerateOopMap::ppop(CellTypeState *out) {
1734 while (!(*out).is_bottom()) {
1735 ppop1(*out++);
1736 }
1737 }
1738
1739 void GenerateOopMap::ppush1(CellTypeState in) {
1740 assert(in.is_reference() || in.is_inline_type(), "sanity check");
1741 push(in);
1742 }
1743
1744 void GenerateOopMap::ppush(CellTypeState *in) {
1745 while (!(*in).is_bottom()) {
1746 ppush1(*in++);
1747 }
1748 }
1749
1750 void GenerateOopMap::pp(CellTypeState *in, CellTypeState *out) {
1751 ppop(in);
1752 ppush(out);
1753 }
1754
1755 void GenerateOopMap::pp_new_ref(CellTypeState *in, int bci) {
1756 ppop(in);
1757 ppush1(CellTypeState::make_line_ref(bci));
1758 }
1759
1760 void GenerateOopMap::ppop_any(int poplen) {
1761 if (_stack_top >= poplen) {
1762 _stack_top -= poplen;
1763 } else {
1764 verify_error("stack underflow");
1765 }
1766 }
1767
1768 // Replace all occurrences of the state 'match' with the state 'replace'
1769 // in our current state vector.
1770 void GenerateOopMap::replace_all_CTS_matches(CellTypeState match,
1771 CellTypeState replace) {
1772 int i;
1773 int len = _max_locals + _stack_top;
1774 bool change = false;
1775
1776 for (i = len - 1; i >= 0; i--) {
1777 if (match.equal(_state[i])) {
1778 _state[i] = replace;
1779 }
1780 }
1781
1782 if (_monitor_top > 0) {
1783 int base = _max_locals + _max_stack;
1784 len = base + _monitor_top;
1785 for (i = len - 1; i >= base; i--) {
1786 if (match.equal(_state[i])) {
1787 _state[i] = replace;
1788 }
1789 }
1790 }
1791 }
1792
1793 void GenerateOopMap::do_checkcast() {
1794 CellTypeState actual = pop();
1795 check_type(refCTS, actual);
1796 push(actual);
1797 }
1798
1799 void GenerateOopMap::do_monitorenter(int bci) {
1800 CellTypeState actual = pop();
1801 if (_monitor_top == bad_monitors) {
1802 return;
1803 }
1804
1805 // Bail out when we get repeated locks on an identical monitor. This case
1806 // isn't too hard to handle and can be made to work if supporting nested
1807 // redundant synchronized statements becomes a priority.
1808 //
1809 // See also "Note" in do_monitorexit(), below.
1810 if (actual.is_lock_reference()) {
1811 _monitor_top = bad_monitors;
1812 _monitor_safe = false;
1813
1814 if (log_is_enabled(Info, monitormismatch)) {
1815 report_monitor_mismatch("nested redundant lock -- bailout...");
1816 }
1817 return;
1818 }
1819
1820 CellTypeState lock = CellTypeState::make_lock_ref(bci);
1821 check_type(refCTS, actual);
1822 if (!actual.is_info_top()) {
1823 replace_all_CTS_matches(actual, lock);
1824 monitor_push(lock);
1825 }
1826 }
1827
1828 void GenerateOopMap::do_monitorexit(int bci) {
1829 CellTypeState actual = pop();
1830 if (_monitor_top == bad_monitors) {
1831 return;
1832 }
1833 check_type(refCTS, actual);
1834 CellTypeState expected = monitor_pop();
1835 if (!actual.is_lock_reference() || !expected.equal(actual)) {
1836 // The monitor we are exiting is not verifiably the one
1837 // on the top of our monitor stack. This causes a monitor
1838 // mismatch.
1839 _monitor_top = bad_monitors;
1840 _monitor_safe = false;
1841
1842 // We need to mark this basic block as changed so that
1843 // this monitorexit will be visited again. We need to
1844 // do this to ensure that we have accounted for the
1845 // possibility that this bytecode will throw an
1846 // exception.
1847 BasicBlock* bb = get_basic_block_containing(bci);
1848 guarantee(bb != NULL, "no basic block for bci");
1849 bb->set_changed(true);
1850 bb->_monitor_top = bad_monitors;
1851
1852 if (log_is_enabled(Info, monitormismatch)) {
1853 report_monitor_mismatch("improper monitor pair");
1854 }
1855 } else {
1856 // This code is a fix for the case where we have repeated
1857 // locking of the same object in straightline code. We clear
1858 // out the lock when it is popped from the monitor stack
1859 // and replace it with an unobtrusive reference value that can
1860 // be locked again.
1861 //
1862 // Note: when generateOopMap is fixed to properly handle repeated,
1863 // nested, redundant locks on the same object, then this
1864 // fix will need to be removed at that time.
1865 replace_all_CTS_matches(actual, CellTypeState::make_line_ref(bci));
1866 }
1867 }
1868
1869 void GenerateOopMap::do_return_monitor_check() {
1870 if (_monitor_top > 0) {
1871 // The monitor stack must be empty when we leave the method
1872 // for the monitors to be properly matched.
1873 _monitor_safe = false;
1874
1875 // Since there are no successors to the *return bytecode, it
1876 // isn't necessary to set _monitor_top to bad_monitors.
1877
1878 if (log_is_enabled(Info, monitormismatch)) {
1879 report_monitor_mismatch("non-empty monitor stack at return");
1880 }
1881 }
1882 }
1883
1884 void GenerateOopMap::do_jsr(int targ_bci) {
1885 push(CellTypeState::make_addr(targ_bci));
1886 }
1887
1888
1889
1890 void GenerateOopMap::do_ldc(int bci) {
1891 Bytecode_loadconstant ldc(methodHandle(Thread::current(), method()), bci);
1892 ConstantPool* cp = method()->constants();
1893 constantTag tag = cp->tag_at(ldc.pool_index()); // idx is index in resolved_references
1894 BasicType bt = ldc.result_type();
1895 #ifdef ASSERT
1896 BasicType tag_bt = (tag.is_dynamic_constant() || tag.is_dynamic_constant_in_error()) ? bt : tag.basic_type();
1897 assert(bt == tag_bt, "same result");
1898 #endif
1899 CellTypeState cts;
1900 if (is_reference_type(bt)) { // could be T_ARRAY with condy
1901 assert(!tag.is_string_index() && !tag.is_klass_index(), "Unexpected index tag");
1902 cts = CellTypeState::make_line_ref(bci);
1903 } else {
1904 cts = valCTS;
1905 }
1906 ppush1(cts);
1907 }
1908
1909 void GenerateOopMap::do_multianewarray(int dims, int bci) {
1910 assert(dims >= 1, "sanity check");
1911 for(int i = dims -1; i >=0; i--) {
1912 ppop1(valCTS);
1913 }
1914 ppush1(CellTypeState::make_line_ref(bci));
1915 }
1916
1917 void GenerateOopMap::do_astore(int idx) {
1918 CellTypeState r_or_p = pop();
1919 if (!r_or_p.is_address() && !r_or_p.is_reference()) {
1920 // We actually expected ref or pc, but we only report that we expected a ref. It does not
1921 // really matter (at least for now)
1922 verify_error("wrong type on stack (found: %c, expected: {pr})", r_or_p.to_char());
1923 return;
1924 }
1925 set_var(idx, r_or_p);
1926 }
1927
1928 // Copies bottom/zero terminated CTS string from "src" into "dst".
1929 // Does NOT terminate with a bottom. Returns the number of cells copied.
1930 int GenerateOopMap::copy_cts(CellTypeState *dst, CellTypeState *src) {
1931 int idx = 0;
1932 while (!src[idx].is_bottom()) {
1933 dst[idx] = src[idx];
1934 idx++;
1935 }
1936 return idx;
1937 }
1938
1939 void GenerateOopMap::do_field(int is_get, int is_static, int idx, int bci) {
1940 // Dig up signature for field in constant pool
1941 ConstantPool* cp = method()->constants();
1942 int nameAndTypeIdx = cp->name_and_type_ref_index_at(idx);
1943 int signatureIdx = cp->signature_ref_index_at(nameAndTypeIdx);
1944 Symbol* signature = cp->symbol_at(signatureIdx);
1945
1946 CellTypeState temp[4];
1947 CellTypeState *eff = signature_to_effect(signature, bci, temp);
1948
1949 CellTypeState in[4];
1950 CellTypeState *out;
1951 int i = 0;
1952
1953 if (is_get) {
1954 out = eff;
1955 } else {
1956 out = epsilonCTS;
1957 i = copy_cts(in, eff);
1958 }
1959 if (!is_static) {
1960 in[i++] = CellTypeState::ref;
1961 }
1962 in[i] = CellTypeState::bottom;
1963 assert(i<=3, "sanity check");
1964 pp(in, out);
1965 }
1966
1967 void GenerateOopMap::do_method(int is_static, int idx, int bci) {
1968 // Dig up signature for field in constant pool
1969 ConstantPool* cp = _method->constants();
1970 Symbol* signature = cp->signature_ref_at(idx);
1971
1972 // Parse method signature
1973 CellTypeState out[4];
1974 CellTypeState in[MAXARGSIZE+1]; // Includes result
1975 ComputeCallStack cse(signature);
1976
1977 // Compute return type
1978 int res_length= cse.compute_for_returntype(out);
1979
1980 // Temporary hack.
1981 if (out[0].equal(CellTypeState::ref) && out[1].equal(CellTypeState::bottom)) {
1982 out[0] = CellTypeState::make_line_ref(bci);
1983 }
1984
1985 assert(res_length<=4, "max value should be vv");
1986
1987 // Compute arguments
1988 int arg_length = cse.compute_for_parameters(is_static != 0, in);
1989 assert(arg_length<=MAXARGSIZE, "too many locals");
1990
1991 // Pop arguments
1992 for (int i = arg_length - 1; i >= 0; i--) ppop1(in[i]);// Do args in reverse order.
1993
1994 // Report results
1995 if (_report_result_for_send == true) {
1996 fill_stackmap_for_opcodes(_itr_send, vars(), stack(), _stack_top);
1997 _report_result_for_send = false;
1998 }
1999
2000 // Push return address
2001 ppush(out);
2002 }
2003
2004 void GenerateOopMap::do_withfield(int idx, int bci) {
2005 // Dig up signature for field in constant pool
2006 ConstantPool* cp = method()->constants();
2007 int nameAndTypeIdx = cp->name_and_type_ref_index_at(idx);
2008 int signatureIdx = cp->signature_ref_index_at(nameAndTypeIdx);
2009 Symbol* signature = cp->symbol_at(signatureIdx);
2010
2011 // Parse signature (especially simple for fields)
2012 assert(signature->utf8_length() > 0,
2013 "field signatures cannot have zero length");
2014 // The signature is UFT8 encoded, but the first char is always ASCII for signatures.
2015 CellTypeState temp[4];
2016 CellTypeState *eff = signature_to_effect(signature, bci, temp);
2017
2018 CellTypeState in[4];
2019 int i = copy_cts(in, eff);
2020 in[i++] = CellTypeState::ref;
2021 in[i] = CellTypeState::bottom;
2022 assert(i <= 3, "sanity check");
2023
2024 CellTypeState out[2];
2025 out[0] = CellTypeState::ref;
2026 out[1] = CellTypeState::bottom;
2027
2028 pp(in, out);
2029 }
2030
2031 // This is used to parse the signature for fields, since they are very simple...
2032 CellTypeState *GenerateOopMap::signature_to_effect(const Symbol* sig, int bci, CellTypeState *out) {
2033 // Object and array
2034 BasicType bt = Signature::basic_type(sig);
2035 if (is_reference_type(bt)) {
2036 out[0] = CellTypeState::make_line_ref(bci);
2037 out[1] = CellTypeState::bottom;
2038 return out;
2039 }
2040 if (is_double_word_type(bt)) return vvCTS; // Long and Double
2041 if (bt == T_VOID) return epsilonCTS; // Void
2042 return vCTS; // Otherwise
2043 }
2044
2045 uint64_t GenerateOopMap::_total_byte_count = 0;
2046 elapsedTimer GenerateOopMap::_total_oopmap_time;
2047
2048 // This function assumes "bcs" is at a "ret" instruction and that the vars
2049 // state is valid for that instruction. Furthermore, the ret instruction
2050 // must be the last instruction in "bb" (we store information about the
2051 // "ret" in "bb").
2052 void GenerateOopMap::ret_jump_targets_do(BytecodeStream *bcs, jmpFct_t jmpFct, int varNo, int *data) {
2053 CellTypeState ra = vars()[varNo];
2054 if (!ra.is_good_address()) {
2055 verify_error("ret returns from two jsr subroutines?");
2056 return;
2057 }
2058 int target = ra.get_info();
2059
2060 RetTableEntry* rtEnt = _rt.find_jsrs_for_target(target);
2061 int bci = bcs->bci();
2062 for (int i = 0; i < rtEnt->nof_jsrs(); i++) {
2063 int target_bci = rtEnt->jsrs(i);
2064 // Make sure a jrtRet does not set the changed bit for dead basicblock.
2065 BasicBlock* jsr_bb = get_basic_block_containing(target_bci - 1);
2066 debug_only(BasicBlock* target_bb = &jsr_bb[1];)
2067 assert(target_bb == get_basic_block_at(target_bci), "wrong calc. of successor basicblock");
2068 bool alive = jsr_bb->is_alive();
2069 if (TraceNewOopMapGeneration) {
2070 tty->print("pc = %d, ret -> %d alive: %s\n", bci, target_bci, alive ? "true" : "false");
2071 }
2072 if (alive) jmpFct(this, target_bci, data);
2073 }
2074 }
2075
2076 //
2077 // Debug method
2078 //
2079 char* GenerateOopMap::state_vec_to_string(CellTypeState* vec, int len) {
2080 #ifdef ASSERT
2081 int checklen = MAX3(_max_locals, _max_stack, _max_monitors) + 1;
2082 assert(len < checklen, "state_vec_buf overflow");
2083 #endif
2084 for (int i = 0; i < len; i++) _state_vec_buf[i] = vec[i].to_char();
2085 _state_vec_buf[len] = 0;
2086 return _state_vec_buf;
2087 }
2088
2089 void GenerateOopMap::print_time() {
2090 tty->print_cr ("Accumulated oopmap times:");
2091 tty->print_cr ("---------------------------");
2092 tty->print_cr (" Total : %3.3f sec.", GenerateOopMap::_total_oopmap_time.seconds());
2093 tty->print_cr (" (%3.0f bytecodes per sec) ",
2094 GenerateOopMap::_total_byte_count / GenerateOopMap::_total_oopmap_time.seconds());
2095 }
2096
2097 //
2098 // ============ Main Entry Point ===========
2099 //
2100 GenerateOopMap::GenerateOopMap(const methodHandle& method) {
2101 // We have to initialize all variables here, that can be queried directly
2102 _method = method;
2103 _max_locals=0;
2104 _init_vars = NULL;
2105
2106 #ifndef PRODUCT
2107 // If we are doing a detailed trace, include the regular trace information.
2108 if (TraceNewOopMapGenerationDetailed) {
2109 TraceNewOopMapGeneration = true;
2110 }
2111 #endif
2112 }
2113
2114 bool GenerateOopMap::compute_map(Thread* current) {
2115 #ifndef PRODUCT
2116 if (TimeOopMap2) {
2117 method()->print_short_name(tty);
2118 tty->print(" ");
2119 }
2120 if (TimeOopMap) {
2121 _total_byte_count += method()->code_size();
2122 }
2123 #endif
2124 TraceTime t_single("oopmap time", TimeOopMap2);
2125 TraceTime t_all(NULL, &_total_oopmap_time, TimeOopMap);
2126
2127 // Initialize values
2128 _got_error = false;
2129 _conflict = false;
2130 _max_locals = method()->max_locals();
2131 _max_stack = method()->max_stack();
2132 _has_exceptions = (method()->has_exception_handler());
2133 _nof_refval_conflicts = 0;
2134 _init_vars = new GrowableArray<intptr_t>(5); // There are seldom more than 5 init_vars
2135 _report_result = false;
2136 _report_result_for_send = false;
2137 _new_var_map = NULL;
2138 _ret_adr_tos = new GrowableArray<intptr_t>(5); // 5 seems like a good number;
2139 _did_rewriting = false;
2140 _did_relocation = false;
2141
2142 if (TraceNewOopMapGeneration) {
2143 tty->print("Method name: %s\n", method()->name()->as_C_string());
2144 if (Verbose) {
2145 _method->print_codes();
2146 tty->print_cr("Exception table:");
2147 ExceptionTable excps(method());
2148 for(int i = 0; i < excps.length(); i ++) {
2149 tty->print_cr("[%d - %d] -> %d",
2150 excps.start_pc(i), excps.end_pc(i), excps.handler_pc(i));
2151 }
2152 }
2153 }
2154
2155 // if no code - do nothing
2156 // compiler needs info
2157 if (method()->code_size() == 0 || _max_locals + method()->max_stack() == 0) {
2158 fill_stackmap_prolog(0);
2159 fill_stackmap_epilog();
2160 return true;
2161 }
2162 // Step 1: Compute all jump targets and their return value
2163 if (!_got_error)
2164 _rt.compute_ret_table(_method);
2165
2166 // Step 2: Find all basic blocks and count GC points
2167 if (!_got_error)
2168 mark_bbheaders_and_count_gc_points();
2169
2170 // Step 3: Calculate stack maps
2171 if (!_got_error)
2172 do_interpretation();
2173
2174 // Step 4:Return results
2175 if (!_got_error && report_results())
2176 report_result();
2177
2178 return !_got_error;
2179 }
2180
2181 // Error handling methods
2182 //
2183 // If we compute from a suitable JavaThread then we create an exception for the GenerateOopMap
2184 // calling code to retrieve (via exception()) and throw if desired (in most cases errors are ignored).
2185 // Otherwise it is considered a fatal error to hit malformed bytecode.
2186 void GenerateOopMap::error_work(const char *format, va_list ap) {
2187 _got_error = true;
2188 char msg_buffer[512];
2189 os::vsnprintf(msg_buffer, sizeof(msg_buffer), format, ap);
2190 // Append method name
2191 char msg_buffer2[512];
2192 os::snprintf(msg_buffer2, sizeof(msg_buffer2), "%s in method %s", msg_buffer, method()->name()->as_C_string());
2193 Thread* current = Thread::current();
2194 if (current->can_call_java()) {
2195 _exception = Exceptions::new_exception(JavaThread::cast(current),
2196 vmSymbols::java_lang_LinkageError(),
2197 msg_buffer2);
2198 } else {
2199 fatal("%s", msg_buffer2);
2200 }
2201 }
2202
2203 void GenerateOopMap::report_error(const char *format, ...) {
2204 va_list ap;
2205 va_start(ap, format);
2206 error_work(format, ap);
2207 }
2208
2209 void GenerateOopMap::verify_error(const char *format, ...) {
2210 // We do not distinguish between different types of errors for verification
2211 // errors. Let the verifier give a better message.
2212 report_error("Illegal class file encountered. Try running with -Xverify:all");
2213 }
2214
2215 //
2216 // Report result opcodes
2217 //
2218 void GenerateOopMap::report_result() {
2219
2220 if (TraceNewOopMapGeneration) tty->print_cr("Report result pass");
2221
2222 // We now want to report the result of the parse
2223 _report_result = true;
2224
2225 // Prolog code
2226 fill_stackmap_prolog(_gc_points);
2227
2228 // Mark everything changed, then do one interpretation pass.
2229 for (int i = 0; i<_bb_count; i++) {
2230 if (_basic_blocks[i].is_reachable()) {
2231 _basic_blocks[i].set_changed(true);
2232 interp_bb(&_basic_blocks[i]);
2233 }
2234 }
2235
2236 // Note: Since we are skipping dead-code when we are reporting results, then
2237 // the no. of encountered gc-points might be fewer than the previously number
2238 // we have counted. (dead-code is a pain - it should be removed before we get here)
2239 fill_stackmap_epilog();
2240
2241 // Report initvars
2242 fill_init_vars(_init_vars);
2243
2244 _report_result = false;
2245 }
2246
2247 void GenerateOopMap::result_for_basicblock(int bci) {
2248 if (TraceNewOopMapGeneration) tty->print_cr("Report result pass for basicblock");
2249
2250 // We now want to report the result of the parse
2251 _report_result = true;
2252
2253 // Find basicblock and report results
2254 BasicBlock* bb = get_basic_block_containing(bci);
2255 guarantee(bb != NULL, "no basic block for bci");
2256 assert(bb->is_reachable(), "getting result from unreachable basicblock");
2257 bb->set_changed(true);
2258 interp_bb(bb);
2259 }
2260
2261 //
2262 // Conflict handling code
2263 //
2264
2265 void GenerateOopMap::record_refval_conflict(int varNo) {
2266 assert(varNo>=0 && varNo< _max_locals, "index out of range");
2267
2268 if (TraceOopMapRewrites) {
2269 tty->print("### Conflict detected (local no: %d)\n", varNo);
2270 }
2271
2272 if (!_new_var_map) {
2273 _new_var_map = NEW_RESOURCE_ARRAY(int, _max_locals);
2274 for (int k = 0; k < _max_locals; k++) _new_var_map[k] = k;
2275 }
2276
2277 if ( _new_var_map[varNo] == varNo) {
2278 // Check if max. number of locals has been reached
2279 if (_max_locals + _nof_refval_conflicts >= MAX_LOCAL_VARS) {
2280 report_error("Rewriting exceeded local variable limit");
2281 return;
2282 }
2283 _new_var_map[varNo] = _max_locals + _nof_refval_conflicts;
2284 _nof_refval_conflicts++;
2285 }
2286 }
2287
2288 void GenerateOopMap::rewrite_refval_conflicts()
2289 {
2290 // We can get here two ways: Either a rewrite conflict was detected, or
2291 // an uninitialize reference was detected. In the second case, we do not
2292 // do any rewriting, we just want to recompute the reference set with the
2293 // new information
2294
2295 int nof_conflicts = 0; // Used for debugging only
2296
2297 if ( _nof_refval_conflicts == 0 )
2298 return;
2299
2300 // Check if rewrites are allowed in this parse.
2301 if (!allow_rewrites()) {
2302 fatal("Rewriting method not allowed at this stage");
2303 }
2304
2305
2306 // Tracing flag
2307 _did_rewriting = true;
2308
2309 if (TraceOopMapRewrites) {
2310 tty->print_cr("ref/value conflict for method %s - bytecodes are getting rewritten", method()->name()->as_C_string());
2311 method()->print();
2312 method()->print_codes();
2313 }
2314
2315 assert(_new_var_map!=NULL, "nothing to rewrite");
2316 assert(_conflict==true, "We should not be here");
2317
2318 compute_ret_adr_at_TOS();
2319 if (!_got_error) {
2320 for (int k = 0; k < _max_locals && !_got_error; k++) {
2321 if (_new_var_map[k] != k) {
2322 if (TraceOopMapRewrites) {
2323 tty->print_cr("Rewriting: %d -> %d", k, _new_var_map[k]);
2324 }
2325 rewrite_refval_conflict(k, _new_var_map[k]);
2326 if (_got_error) return;
2327 nof_conflicts++;
2328 }
2329 }
2330 }
2331
2332 assert(nof_conflicts == _nof_refval_conflicts, "sanity check");
2333
2334 // Adjust the number of locals
2335 method()->set_max_locals(_max_locals+_nof_refval_conflicts);
2336 _max_locals += _nof_refval_conflicts;
2337
2338 // That was that...
2339 _new_var_map = NULL;
2340 _nof_refval_conflicts = 0;
2341 }
2342
2343 void GenerateOopMap::rewrite_refval_conflict(int from, int to) {
2344 bool startOver;
2345 do {
2346 // Make sure that the BytecodeStream is constructed in the loop, since
2347 // during rewriting a new method is going to be used, and the next time
2348 // around we want to use that.
2349 BytecodeStream bcs(_method);
2350 startOver = false;
2351
2352 while( !startOver && !_got_error &&
2353 // test bcs in case method changed and it became invalid
2354 bcs.next() >=0) {
2355 startOver = rewrite_refval_conflict_inst(&bcs, from, to);
2356 }
2357 } while (startOver && !_got_error);
2358 }
2359
2360 /* If the current instruction is one that uses local variable "from"
2361 in a ref way, change it to use "to". There's a subtle reason why we
2362 renumber the ref uses and not the non-ref uses: non-ref uses may be
2363 2 slots wide (double, long) which would necessitate keeping track of
2364 whether we should add one or two variables to the method. If the change
2365 affected the width of some instruction, returns "TRUE"; otherwise, returns "FALSE".
2366 Another reason for moving ref's value is for solving (addr, ref) conflicts, which
2367 both uses aload/astore methods.
2368 */
2369 bool GenerateOopMap::rewrite_refval_conflict_inst(BytecodeStream *itr, int from, int to) {
2370 Bytecodes::Code bc = itr->code();
2371 int index;
2372 int bci = itr->bci();
2373
2374 if (is_aload(itr, &index) && index == from) {
2375 if (TraceOopMapRewrites) {
2376 tty->print_cr("Rewriting aload at bci: %d", bci);
2377 }
2378 return rewrite_load_or_store(itr, Bytecodes::_aload, Bytecodes::_aload_0, to);
2379 }
2380
2381 if (is_astore(itr, &index) && index == from) {
2382 if (!stack_top_holds_ret_addr(bci)) {
2383 if (TraceOopMapRewrites) {
2384 tty->print_cr("Rewriting astore at bci: %d", bci);
2385 }
2386 return rewrite_load_or_store(itr, Bytecodes::_astore, Bytecodes::_astore_0, to);
2387 } else {
2388 if (TraceOopMapRewrites) {
2389 tty->print_cr("Suppress rewriting of astore at bci: %d", bci);
2390 }
2391 }
2392 }
2393
2394 return false;
2395 }
2396
2397 // The argument to this method is:
2398 // bc : Current bytecode
2399 // bcN : either _aload or _astore
2400 // bc0 : either _aload_0 or _astore_0
2401 bool GenerateOopMap::rewrite_load_or_store(BytecodeStream *bcs, Bytecodes::Code bcN, Bytecodes::Code bc0, unsigned int varNo) {
2402 assert(bcN == Bytecodes::_astore || bcN == Bytecodes::_aload, "wrong argument (bcN)");
2403 assert(bc0 == Bytecodes::_astore_0 || bc0 == Bytecodes::_aload_0, "wrong argument (bc0)");
2404 int ilen = Bytecodes::length_at(_method(), bcs->bcp());
2405 int newIlen;
2406
2407 if (ilen == 4) {
2408 // Original instruction was wide; keep it wide for simplicity
2409 newIlen = 4;
2410 } else if (varNo < 4)
2411 newIlen = 1;
2412 else if (varNo >= 256)
2413 newIlen = 4;
2414 else
2415 newIlen = 2;
2416
2417 // If we need to relocate in order to patch the byte, we
2418 // do the patching in a temp. buffer, that is passed to the reloc.
2419 // The patching of the bytecode stream is then done by the Relocator.
2420 // This is necessary, since relocating the instruction at a certain bci, might
2421 // also relocate that instruction, e.g., if a _goto before it gets widen to a _goto_w.
2422 // Hence, we do not know which bci to patch after relocation.
2423
2424 assert(newIlen <= 4, "sanity check");
2425 u_char inst_buffer[4]; // Max. instruction size is 4.
2426 address bcp;
2427
2428 if (newIlen != ilen) {
2429 // Relocation needed do patching in temp. buffer
2430 bcp = (address)inst_buffer;
2431 } else {
2432 bcp = _method->bcp_from(bcs->bci());
2433 }
2434
2435 // Patch either directly in Method* or in temp. buffer
2436 if (newIlen == 1) {
2437 assert(varNo < 4, "varNo too large");
2438 *bcp = bc0 + varNo;
2439 } else if (newIlen == 2) {
2440 assert(varNo < 256, "2-byte index needed!");
2441 *(bcp + 0) = bcN;
2442 *(bcp + 1) = varNo;
2443 } else {
2444 assert(newIlen == 4, "Wrong instruction length");
2445 *(bcp + 0) = Bytecodes::_wide;
2446 *(bcp + 1) = bcN;
2447 Bytes::put_Java_u2(bcp+2, varNo);
2448 }
2449
2450 if (newIlen != ilen) {
2451 expand_current_instr(bcs->bci(), ilen, newIlen, inst_buffer);
2452 }
2453
2454
2455 return (newIlen != ilen);
2456 }
2457
2458 class RelocCallback : public RelocatorListener {
2459 private:
2460 GenerateOopMap* _gom;
2461 public:
2462 RelocCallback(GenerateOopMap* gom) { _gom = gom; };
2463
2464 // Callback method
2465 virtual void relocated(int bci, int delta, int new_code_length) {
2466 _gom->update_basic_blocks (bci, delta, new_code_length);
2467 _gom->update_ret_adr_at_TOS(bci, delta);
2468 _gom->_rt.update_ret_table (bci, delta);
2469 }
2470 };
2471
2472 // Returns true if expanding was successful. Otherwise, reports an error and
2473 // returns false.
2474 void GenerateOopMap::expand_current_instr(int bci, int ilen, int newIlen, u_char inst_buffer[]) {
2475 JavaThread* THREAD = JavaThread::current(); // For exception macros.
2476 RelocCallback rcb(this);
2477 Relocator rc(_method, &rcb);
2478 methodHandle m= rc.insert_space_at(bci, newIlen, inst_buffer, THREAD);
2479 if (m.is_null() || HAS_PENDING_EXCEPTION) {
2480 report_error("could not rewrite method - exception occurred or bytecode buffer overflow");
2481 return;
2482 }
2483
2484 // Relocator returns a new method.
2485 _did_relocation = true;
2486 _method = m;
2487 }
2488
2489
2490 bool GenerateOopMap::is_astore(BytecodeStream *itr, int *index) {
2491 Bytecodes::Code bc = itr->code();
2492 switch(bc) {
2493 case Bytecodes::_astore_0:
2494 case Bytecodes::_astore_1:
2495 case Bytecodes::_astore_2:
2496 case Bytecodes::_astore_3:
2497 *index = bc - Bytecodes::_astore_0;
2498 return true;
2499 case Bytecodes::_astore:
2500 *index = itr->get_index();
2501 return true;
2502 default:
2503 return false;
2504 }
2505 }
2506
2507 bool GenerateOopMap::is_aload(BytecodeStream *itr, int *index) {
2508 Bytecodes::Code bc = itr->code();
2509 switch(bc) {
2510 case Bytecodes::_aload_0:
2511 case Bytecodes::_aload_1:
2512 case Bytecodes::_aload_2:
2513 case Bytecodes::_aload_3:
2514 *index = bc - Bytecodes::_aload_0;
2515 return true;
2516
2517 case Bytecodes::_aload:
2518 *index = itr->get_index();
2519 return true;
2520
2521 default:
2522 return false;
2523 }
2524 }
2525
2526
2527 // Return true iff the top of the operand stack holds a return address at
2528 // the current instruction
2529 bool GenerateOopMap::stack_top_holds_ret_addr(int bci) {
2530 for(int i = 0; i < _ret_adr_tos->length(); i++) {
2531 if (_ret_adr_tos->at(i) == bci)
2532 return true;
2533 }
2534
2535 return false;
2536 }
2537
2538 void GenerateOopMap::compute_ret_adr_at_TOS() {
2539 assert(_ret_adr_tos != NULL, "must be initialized");
2540 _ret_adr_tos->clear();
2541
2542 for (int i = 0; i < bb_count(); i++) {
2543 BasicBlock* bb = &_basic_blocks[i];
2544
2545 // Make sure to only check basicblocks that are reachable
2546 if (bb->is_reachable()) {
2547
2548 // For each Basic block we check all instructions
2549 BytecodeStream bcs(_method);
2550 bcs.set_interval(bb->_bci, next_bb_start_pc(bb));
2551
2552 restore_state(bb);
2553
2554 while (bcs.next()>=0 && !_got_error) {
2555 // TDT: should this be is_good_address() ?
2556 if (_stack_top > 0 && stack()[_stack_top-1].is_address()) {
2557 _ret_adr_tos->append(bcs.bci());
2558 if (TraceNewOopMapGeneration) {
2559 tty->print_cr("Ret_adr TOS at bci: %d", bcs.bci());
2560 }
2561 }
2562 interp1(&bcs);
2563 }
2564 }
2565 }
2566 }
2567
2568 void GenerateOopMap::update_ret_adr_at_TOS(int bci, int delta) {
2569 for(int i = 0; i < _ret_adr_tos->length(); i++) {
2570 int v = _ret_adr_tos->at(i);
2571 if (v > bci) _ret_adr_tos->at_put(i, v + delta);
2572 }
2573 }
2574
2575 // ===================================================================
2576
2577 #ifndef PRODUCT
2578 int ResolveOopMapConflicts::_nof_invocations = 0;
2579 int ResolveOopMapConflicts::_nof_rewrites = 0;
2580 int ResolveOopMapConflicts::_nof_relocations = 0;
2581 #endif
2582
2583 methodHandle ResolveOopMapConflicts::do_potential_rewrite(TRAPS) {
2584 if (!compute_map(THREAD)) {
2585 THROW_HANDLE_(exception(), methodHandle());
2586 }
2587
2588 #ifndef PRODUCT
2589 // Tracking and statistics
2590 if (PrintRewrites) {
2591 _nof_invocations++;
2592 if (did_rewriting()) {
2593 _nof_rewrites++;
2594 if (did_relocation()) _nof_relocations++;
2595 tty->print("Method was rewritten %s: ", (did_relocation()) ? "and relocated" : "");
2596 method()->print_value(); tty->cr();
2597 tty->print_cr("Cand.: %d rewrts: %d (%d%%) reloc.: %d (%d%%)",
2598 _nof_invocations,
2599 _nof_rewrites, (_nof_rewrites * 100) / _nof_invocations,
2600 _nof_relocations, (_nof_relocations * 100) / _nof_invocations);
2601 }
2602 }
2603 #endif
2604 return methodHandle(THREAD, method());
2605 }