1 /*
2 * Copyright (c) 2015, 2018, 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 "code/compiledIC.hpp"
27 #include "code/compiledMethod.inline.hpp"
28 #include "code/scopeDesc.hpp"
29 #include "code/codeCache.hpp"
30 #include "interpreter/bytecode.inline.hpp"
31 #include "logging/log.hpp"
32 #include "logging/logTag.hpp"
33 #include "memory/resourceArea.hpp"
34 #include "oops/methodData.hpp"
35 #include "oops/method.inline.hpp"
36 #include "prims/methodHandles.hpp"
37 #include "runtime/handles.inline.hpp"
38 #include "runtime/mutexLocker.hpp"
39
40 CompiledMethod::CompiledMethod(Method* method, const char* name, CompilerType type, const CodeBlobLayout& layout, int frame_complete_offset, int frame_size, ImmutableOopMapSet* oop_maps, bool caller_must_gc_arguments)
41 : CodeBlob(name, type, layout, frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),
42 _mark_for_deoptimization_status(not_marked), _method(method) {
43 init_defaults();
44 }
45
46 CompiledMethod::CompiledMethod(Method* method, const char* name, CompilerType type, int size, int header_size, CodeBuffer* cb, int frame_complete_offset, int frame_size, OopMapSet* oop_maps, bool caller_must_gc_arguments)
47 : CodeBlob(name, type, CodeBlobLayout((address) this, size, header_size, cb), cb, frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),
48 _mark_for_deoptimization_status(not_marked), _method(method) {
49 init_defaults();
50 }
51
52 void CompiledMethod::init_defaults() {
53 _has_unsafe_access = 0;
54 _has_method_handle_invokes = 0;
55 _lazy_critical_native = 0;
56 _has_wide_vectors = 0;
57 _unloading_clock = 0;
58 }
59
60 bool CompiledMethod::is_method_handle_return(address return_pc) {
61 if (!has_method_handle_invokes()) return false;
62 PcDesc* pd = pc_desc_at(return_pc);
63 if (pd == NULL)
64 return false;
65 return pd->is_method_handle_invoke();
66 }
67
68 // Returns a string version of the method state.
69 const char* CompiledMethod::state() const {
70 int state = get_state();
71 switch (state) {
72 case not_installed:
73 return "not installed";
74 case in_use:
75 return "in use";
76 case not_used:
77 return "not_used";
78 case not_entrant:
79 return "not_entrant";
80 case zombie:
81 return "zombie";
82 case unloaded:
83 return "unloaded";
84 default:
85 fatal("unexpected method state: %d", state);
86 return NULL;
87 }
88 }
89
90 //-----------------------------------------------------------------------------
91
92 ExceptionCache* CompiledMethod::exception_cache_acquire() const {
93 return OrderAccess::load_acquire(&_exception_cache);
94 }
95
96 void CompiledMethod::add_exception_cache_entry(ExceptionCache* new_entry) {
97 assert(ExceptionCache_lock->owned_by_self(),"Must hold the ExceptionCache_lock");
98 assert(new_entry != NULL,"Must be non null");
99 assert(new_entry->next() == NULL, "Must be null");
100
101 for (;;) {
102 ExceptionCache *ec = exception_cache();
103 if (ec != NULL) {
104 Klass* ex_klass = ec->exception_type();
105 if (!ex_klass->is_loader_alive()) {
106 // We must guarantee that entries are not inserted with new next pointer
107 // edges to ExceptionCache entries with dead klasses, due to bad interactions
108 // with concurrent ExceptionCache cleanup. Therefore, the inserts roll
109 // the head pointer forward to the first live ExceptionCache, so that the new
110 // next pointers always point at live ExceptionCaches, that are not removed due
111 // to concurrent ExceptionCache cleanup.
112 ExceptionCache* next = ec->next();
113 if (Atomic::cmpxchg(next, &_exception_cache, ec) == ec) {
114 CodeCache::release_exception_cache(ec);
115 }
116 continue;
117 }
118 ec = exception_cache();
119 if (ec != NULL) {
120 new_entry->set_next(ec);
121 }
122 }
123 if (Atomic::cmpxchg(new_entry, &_exception_cache, ec) == ec) {
124 return;
125 }
126 }
127 }
128
129 void CompiledMethod::clean_exception_cache() {
130 // For each nmethod, only a single thread may call this cleanup function
131 // at the same time, whether called in STW cleanup or concurrent cleanup.
132 // Note that if the GC is processing exception cache cleaning in a concurrent phase,
133 // then a single writer may contend with cleaning up the head pointer to the
134 // first ExceptionCache node that has a Klass* that is alive. That is fine,
135 // as long as there is no concurrent cleanup of next pointers from concurrent writers.
136 // And the concurrent writers do not clean up next pointers, only the head.
137 // Also note that concurent readers will walk through Klass* pointers that are not
138 // alive. That does not cause ABA problems, because Klass* is deleted after
139 // a handshake with all threads, after all stale ExceptionCaches have been
140 // unlinked. That is also when the CodeCache::exception_cache_free_list()
141 ExceptionCache* prev = NULL;
142 ExceptionCache* curr = exception_cache_acquire();
143
144 while (curr != NULL) {
145 ExceptionCache* next = curr->next();
146
147 if (!curr->exception_type()->is_loader_alive()) {
148 if (prev == NULL) {
149 // Try to clean head; this is contended by concurrent inserts, that
150 // both lazily clean the head, and insert entries at the head. If
151 // the CAS fails, the operation is restarted.
152 if (Atomic::cmpxchg(next, &_exception_cache, curr) != curr) {
153 prev = NULL;
154 curr = exception_cache_acquire();
155 continue;
156 }
157 } else {
158 // It is impossible to during cleanup connect the next pointer to
159 // an ExceptionCache that has not been published before a safepoint
160 // prior to the cleanup. Therefore, release is not required.
161 prev->set_next(next);
162 }
163 // prev stays the same.
164
165 CodeCache::release_exception_cache(curr);
166 } else {
167 prev = curr;
168 }
169
170 curr = next;
171 }
172 }
173
174 // public method for accessing the exception cache
175 // These are the public access methods.
176 address CompiledMethod::handler_for_exception_and_pc(Handle exception, address pc) {
177 // We never grab a lock to read the exception cache, so we may
178 // have false negatives. This is okay, as it can only happen during
179 // the first few exception lookups for a given nmethod.
180 ExceptionCache* ec = exception_cache_acquire();
181 while (ec != NULL) {
182 address ret_val;
183 if ((ret_val = ec->match(exception,pc)) != NULL) {
184 return ret_val;
185 }
186 ec = ec->next();
187 }
188 return NULL;
189 }
190
191 void CompiledMethod::add_handler_for_exception_and_pc(Handle exception, address pc, address handler) {
192 // There are potential race conditions during exception cache updates, so we
193 // must own the ExceptionCache_lock before doing ANY modifications. Because
194 // we don't lock during reads, it is possible to have several threads attempt
195 // to update the cache with the same data. We need to check for already inserted
196 // copies of the current data before adding it.
197
198 MutexLocker ml(ExceptionCache_lock);
199 ExceptionCache* target_entry = exception_cache_entry_for_exception(exception);
200
201 if (target_entry == NULL || !target_entry->add_address_and_handler(pc,handler)) {
202 target_entry = new ExceptionCache(exception,pc,handler);
203 add_exception_cache_entry(target_entry);
204 }
205 }
206
207 // private method for handling exception cache
208 // These methods are private, and used to manipulate the exception cache
209 // directly.
210 ExceptionCache* CompiledMethod::exception_cache_entry_for_exception(Handle exception) {
211 ExceptionCache* ec = exception_cache_acquire();
212 while (ec != NULL) {
213 if (ec->match_exception_with_space(exception)) {
214 return ec;
215 }
216 ec = ec->next();
217 }
218 return NULL;
219 }
220
221 //-------------end of code for ExceptionCache--------------
222
223 bool CompiledMethod::is_at_poll_return(address pc) {
224 RelocIterator iter(this, pc, pc+1);
225 while (iter.next()) {
226 if (iter.type() == relocInfo::poll_return_type)
227 return true;
228 }
229 return false;
230 }
231
232
233 bool CompiledMethod::is_at_poll_or_poll_return(address pc) {
234 RelocIterator iter(this, pc, pc+1);
235 while (iter.next()) {
236 relocInfo::relocType t = iter.type();
237 if (t == relocInfo::poll_return_type || t == relocInfo::poll_type)
238 return true;
239 }
240 return false;
241 }
242
243 void CompiledMethod::verify_oop_relocations() {
244 // Ensure sure that the code matches the current oop values
245 RelocIterator iter(this, NULL, NULL);
246 while (iter.next()) {
247 if (iter.type() == relocInfo::oop_type) {
248 oop_Relocation* reloc = iter.oop_reloc();
249 if (!reloc->oop_is_immediate()) {
250 reloc->verify_oop_relocation();
251 }
252 }
253 }
254 }
255
256
257 ScopeDesc* CompiledMethod::scope_desc_at(address pc) {
258 PcDesc* pd = pc_desc_at(pc);
259 guarantee(pd != NULL, "scope must be present");
260 return new ScopeDesc(this, pd->scope_decode_offset(),
261 pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),
262 pd->return_oop());
263 }
264
265 ScopeDesc* CompiledMethod::scope_desc_near(address pc) {
266 PcDesc* pd = pc_desc_near(pc);
267 guarantee(pd != NULL, "scope must be present");
268 return new ScopeDesc(this, pd->scope_decode_offset(),
269 pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),
270 pd->return_oop());
271 }
272
273 address CompiledMethod::oops_reloc_begin() const {
274 // If the method is not entrant or zombie then a JMP is plastered over the
275 // first few bytes. If an oop in the old code was there, that oop
276 // should not get GC'd. Skip the first few bytes of oops on
277 // not-entrant methods.
278 address low_boundary = verified_entry_point();
279 if (!is_in_use() && is_nmethod()) {
280 low_boundary += NativeJump::instruction_size;
281 // %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
282 // This means that the low_boundary is going to be a little too high.
283 // This shouldn't matter, since oops of non-entrant methods are never used.
284 // In fact, why are we bothering to look at oops in a non-entrant method??
285 }
286 return low_boundary;
287 }
288
289 int CompiledMethod::verify_icholder_relocations() {
290 ResourceMark rm;
291 int count = 0;
292
293 RelocIterator iter(this);
294 while(iter.next()) {
295 if (iter.type() == relocInfo::virtual_call_type) {
296 if (CompiledIC::is_icholder_call_site(iter.virtual_call_reloc(), this)) {
297 CompiledIC *ic = CompiledIC_at(&iter);
298 if (TraceCompiledIC) {
299 tty->print("noticed icholder " INTPTR_FORMAT " ", p2i(ic->cached_icholder()));
300 ic->print();
301 }
302 assert(ic->cached_icholder() != NULL, "must be non-NULL");
303 count++;
304 }
305 }
306 }
307
308 return count;
309 }
310
311 // Method that knows how to preserve outgoing arguments at call. This method must be
312 // called with a frame corresponding to a Java invoke
313 void CompiledMethod::preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map, OopClosure* f) {
314 if (method() != NULL && !method()->is_native()) {
315 address pc = fr.pc();
316 SimpleScopeDesc ssd(this, pc);
317 Bytecode_invoke call(ssd.method(), ssd.bci());
318 bool has_receiver = call.has_receiver();
319 bool has_appendix = call.has_appendix();
320 Symbol* signature = call.signature();
321
322 // The method attached by JIT-compilers should be used, if present.
323 // Bytecode can be inaccurate in such case.
324 Method* callee = attached_method_before_pc(pc);
325 if (callee != NULL) {
326 has_receiver = !(callee->access_flags().is_static());
327 has_appendix = false;
328 signature = callee->signature();
329 }
330
331 fr.oops_compiled_arguments_do(signature, has_receiver, has_appendix, reg_map, f);
332 }
333 }
334
335 Method* CompiledMethod::attached_method(address call_instr) {
336 assert(code_contains(call_instr), "not part of the nmethod");
337 RelocIterator iter(this, call_instr, call_instr + 1);
338 while (iter.next()) {
339 if (iter.addr() == call_instr) {
340 switch(iter.type()) {
341 case relocInfo::static_call_type: return iter.static_call_reloc()->method_value();
342 case relocInfo::opt_virtual_call_type: return iter.opt_virtual_call_reloc()->method_value();
343 case relocInfo::virtual_call_type: return iter.virtual_call_reloc()->method_value();
344 default: break;
345 }
346 }
347 }
348 return NULL; // not found
349 }
350
351 Method* CompiledMethod::attached_method_before_pc(address pc) {
352 if (NativeCall::is_call_before(pc)) {
353 NativeCall* ncall = nativeCall_before(pc);
354 return attached_method(ncall->instruction_address());
355 }
356 return NULL; // not a call
357 }
358
359 void CompiledMethod::clear_inline_caches() {
360 assert(SafepointSynchronize::is_at_safepoint(), "cleaning of IC's only allowed at safepoint");
361 if (is_zombie()) {
362 return;
363 }
364
365 RelocIterator iter(this);
366 while (iter.next()) {
367 iter.reloc()->clear_inline_cache();
368 }
369 }
370
371 // Clear ICStubs of all compiled ICs
372 void CompiledMethod::clear_ic_stubs() {
373 assert_locked_or_safepoint(CompiledIC_lock);
374 ResourceMark rm;
375 RelocIterator iter(this);
376 while(iter.next()) {
377 if (iter.type() == relocInfo::virtual_call_type) {
378 CompiledIC* ic = CompiledIC_at(&iter);
379 ic->clear_ic_stub();
380 }
381 }
382 }
383
384 #ifdef ASSERT
385 // Check class_loader is alive for this bit of metadata.
386 static void check_class(Metadata* md) {
387 Klass* klass = NULL;
388 if (md->is_klass()) {
389 klass = ((Klass*)md);
390 } else if (md->is_method()) {
391 klass = ((Method*)md)->method_holder();
392 } else if (md->is_methodData()) {
393 klass = ((MethodData*)md)->method()->method_holder();
394 } else {
395 md->print();
396 ShouldNotReachHere();
397 }
398 assert(klass->is_loader_alive(), "must be alive");
399 }
400 #endif // ASSERT
401
402
403 void CompiledMethod::clean_ic_if_metadata_is_dead(CompiledIC *ic) {
404 if (ic->is_icholder_call()) {
405 // The only exception is compiledICHolder metdata which may
406 // yet be marked below. (We check this further below).
407 CompiledICHolder* cichk_metdata = ic->cached_icholder();
408
409 if (cichk_metdata->is_loader_alive()) {
410 return;
411 }
412 } else {
413 Metadata* ic_metdata = ic->cached_metadata();
414 if (ic_metdata != NULL) {
415 if (ic_metdata->is_klass()) {
416 if (((Klass*)ic_metdata)->is_loader_alive()) {
417 return;
418 }
419 } else if (ic_metdata->is_method()) {
420 Method* method = (Method*)ic_metdata;
421 assert(!method->is_old(), "old method should have been cleaned");
422 if (method->method_holder()->is_loader_alive()) {
423 return;
424 }
425 } else {
426 ShouldNotReachHere();
427 }
428 }
429 }
430
431 ic->set_to_clean();
432 }
433
434 unsigned char CompiledMethod::_global_unloading_clock = 0;
435
436 void CompiledMethod::increase_unloading_clock() {
437 _global_unloading_clock++;
438 if (_global_unloading_clock == 0) {
439 // _nmethods are allocated with _unloading_clock == 0,
440 // so 0 is never used as a clock value.
441 _global_unloading_clock = 1;
442 }
443 }
444
445 void CompiledMethod::set_unloading_clock(unsigned char unloading_clock) {
446 OrderAccess::release_store(&_unloading_clock, unloading_clock);
447 }
448
449 unsigned char CompiledMethod::unloading_clock() {
450 return OrderAccess::load_acquire(&_unloading_clock);
451 }
452
453
454 // static_stub_Relocations may have dangling references to
455 // nmethods so trim them out here. Otherwise it looks like
456 // compiled code is maintaining a link to dead metadata.
457 void CompiledMethod::clean_ic_stubs() {
458 #ifdef ASSERT
459 address low_boundary = oops_reloc_begin();
460 RelocIterator iter(this, low_boundary);
461 while (iter.next()) {
462 address static_call_addr = NULL;
463 if (iter.type() == relocInfo::opt_virtual_call_type) {
464 CompiledIC* cic = CompiledIC_at(&iter);
465 if (!cic->is_call_to_interpreted()) {
466 static_call_addr = iter.addr();
467 }
468 } else if (iter.type() == relocInfo::static_call_type) {
469 CompiledStaticCall* csc = compiledStaticCall_at(iter.reloc());
470 if (!csc->is_call_to_interpreted()) {
471 static_call_addr = iter.addr();
472 }
473 }
474 if (static_call_addr != NULL) {
475 RelocIterator sciter(this, low_boundary);
476 while (sciter.next()) {
477 if (sciter.type() == relocInfo::static_stub_type &&
478 sciter.static_stub_reloc()->static_call() == static_call_addr) {
479 sciter.static_stub_reloc()->clear_inline_cache();
480 }
481 }
482 }
483 }
484 #endif
485 }
486
487 // This is called at the end of the strong tracing/marking phase of a
488 // GC to unload an nmethod if it contains otherwise unreachable
489 // oops.
490
491 void CompiledMethod::do_unloading(BoolObjectClosure* is_alive) {
492 // Make sure the oop's ready to receive visitors
493 assert(!is_zombie() && !is_unloaded(),
494 "should not call follow on zombie or unloaded nmethod");
495
496 address low_boundary = oops_reloc_begin();
497
498 if (do_unloading_oops(low_boundary, is_alive)) {
499 return;
500 }
501
502 #if INCLUDE_JVMCI
503 if (do_unloading_jvmci()) {
504 return;
505 }
506 #endif
507
508 // Cleanup exception cache and inline caches happens
509 // after all the unloaded methods are found.
510 }
511
512 // Clean references to unloaded nmethods at addr from this one, which is not unloaded.
513 template <class CompiledICorStaticCall>
514 static bool clean_if_nmethod_is_unloaded(CompiledICorStaticCall *ic, address addr, CompiledMethod* from,
515 bool parallel, bool clean_all) {
516 // Ok, to lookup references to zombies here
517 CodeBlob *cb = CodeCache::find_blob_unsafe(addr);
518 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
519 if (nm != NULL) {
520 if (parallel && nm->unloading_clock() != CompiledMethod::global_unloading_clock()) {
521 // The nmethod has not been processed yet.
522 return true;
523 }
524
525 // Clean inline caches pointing to both zombie and not_entrant methods
526 if (clean_all || !nm->is_in_use() || (nm->method()->code() != nm)) {
527 ic->set_to_clean(from->is_alive());
528 assert(ic->is_clean(), "nmethod " PTR_FORMAT "not clean %s", p2i(from), from->method()->name_and_sig_as_C_string());
529 }
530 }
531
532 return false;
533 }
534
535 static bool clean_if_nmethod_is_unloaded(CompiledIC *ic, CompiledMethod* from,
536 bool parallel, bool clean_all = false) {
537 return clean_if_nmethod_is_unloaded(ic, ic->ic_destination(), from, parallel, clean_all);
538 }
539
540 static bool clean_if_nmethod_is_unloaded(CompiledStaticCall *csc, CompiledMethod* from,
541 bool parallel, bool clean_all = false) {
542 return clean_if_nmethod_is_unloaded(csc, csc->destination(), from, parallel, clean_all);
543 }
544
545 bool CompiledMethod::do_unloading_parallel(BoolObjectClosure* is_alive, bool unloading_occurred) {
546 ResourceMark rm;
547
548 // Make sure the oop's ready to receive visitors
549 assert(!is_zombie() && !is_unloaded(),
550 "should not call follow on zombie or unloaded nmethod");
551
552 address low_boundary = oops_reloc_begin();
553
554 if (do_unloading_oops(low_boundary, is_alive)) {
555 return false;
556 }
557
558 #if INCLUDE_JVMCI
559 if (do_unloading_jvmci()) {
560 return false;
561 }
562 #endif
563
564 return unload_nmethod_caches(/*parallel*/true, unloading_occurred);
565 }
566
567 // Cleans caches in nmethods that point to either classes that are unloaded
568 // or nmethods that are unloaded.
569 //
570 // Can be called either in parallel by G1 currently or after all
571 // nmethods are unloaded. Return postponed=true in the parallel case for
572 // inline caches found that point to nmethods that are not yet visited during
573 // the do_unloading walk.
574 bool CompiledMethod::unload_nmethod_caches(bool parallel, bool unloading_occurred) {
575
576 // Exception cache only needs to be called if unloading occurred
577 if (unloading_occurred) {
578 clean_exception_cache();
579 }
580
581 bool postponed = cleanup_inline_caches_impl(parallel, unloading_occurred, /*clean_all*/false);
582
583 // All static stubs need to be cleaned.
584 clean_ic_stubs();
585
586 // Check that the metadata embedded in the nmethod is alive
587 DEBUG_ONLY(metadata_do(check_class));
588
589 return postponed;
590 }
591
592 // Called to clean up after class unloading for live nmethods and from the sweeper
593 // for all methods.
594 bool CompiledMethod::cleanup_inline_caches_impl(bool parallel, bool unloading_occurred, bool clean_all) {
595 assert_locked_or_safepoint(CompiledIC_lock);
596 bool postponed = false;
597 ResourceMark rm;
598
599 // Find all calls in an nmethod and clear the ones that point to non-entrant,
600 // zombie and unloaded nmethods.
601 RelocIterator iter(this, oops_reloc_begin());
602 while(iter.next()) {
603
604 switch (iter.type()) {
605
606 case relocInfo::virtual_call_type:
607 if (unloading_occurred) {
608 // If class unloading occurred we first clear ICs where the cached metadata
609 // is referring to an unloaded klass or method.
610 clean_ic_if_metadata_is_dead(CompiledIC_at(&iter));
611 }
612
613 postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, parallel, clean_all);
614 break;
615
616 case relocInfo::opt_virtual_call_type:
617 postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, parallel, clean_all);
618 break;
619
620 case relocInfo::static_call_type:
621 postponed |= clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), this, parallel, clean_all);
622 break;
623
624 case relocInfo::oop_type:
625 // handled by do_unloading_oops already
626 break;
627
628 case relocInfo::metadata_type:
629 break; // nothing to do.
630
631 default:
632 break;
633 }
634 }
635
636 return postponed;
637 }
638
639 void CompiledMethod::do_unloading_parallel_postponed() {
640 ResourceMark rm;
641
642 // Make sure the oop's ready to receive visitors
643 assert(!is_zombie(),
644 "should not call follow on zombie nmethod");
645
646 RelocIterator iter(this, oops_reloc_begin());
647 while(iter.next()) {
648
649 switch (iter.type()) {
650
651 case relocInfo::virtual_call_type:
652 clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, true);
653 break;
654
655 case relocInfo::opt_virtual_call_type:
656 clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, true);
657 break;
658
659 case relocInfo::static_call_type:
660 clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), this, true);
661 break;
662
663 default:
664 break;
665 }
666 }
667 }
668
669 // Iterating over all nmethods, e.g. with the help of CodeCache::nmethods_do(fun) was found
670 // to not be inherently safe. There is a chance that fields are seen which are not properly
671 // initialized. This happens despite the fact that nmethods_do() asserts the CodeCache_lock
672 // to be held.
673 // To bundle knowledge about necessary checks in one place, this function was introduced.
674 // It is not claimed that these checks are sufficient, but they were found to be necessary.
675 bool CompiledMethod::nmethod_access_is_safe(nmethod* nm) {
676 Method* method = (nm == NULL) ? NULL : nm->method(); // nm->method() may be uninitialized, i.e. != NULL, but invalid
677 return (nm != NULL) && (method != NULL) && (method->signature() != NULL) &&
678 !nm->is_zombie() && !nm->is_not_installed() &&
679 os::is_readable_pointer(method) &&
680 os::is_readable_pointer(method->constants()) &&
681 os::is_readable_pointer(method->signature());
682 }