1 /*
2 * Copyright (c) 2015, 2019, 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/exceptionHandlerTable.hpp"
29 #include "code/scopeDesc.hpp"
30 #include "code/codeCache.hpp"
31 #include "code/icBuffer.hpp"
32 #include "gc/shared/barrierSet.hpp"
33 #include "gc/shared/barrierSetNMethod.hpp"
34 #include "gc/shared/gcBehaviours.hpp"
35 #include "interpreter/bytecode.inline.hpp"
36 #include "logging/log.hpp"
37 #include "logging/logTag.hpp"
38 #include "memory/resourceArea.hpp"
39 #include "oops/methodData.hpp"
40 #include "oops/method.inline.hpp"
41 #include "prims/methodHandles.hpp"
42 #include "runtime/atomic.hpp"
43 #include "runtime/deoptimization.hpp"
44 #include "runtime/handles.inline.hpp"
45 #include "runtime/mutexLocker.hpp"
46 #include "runtime/sharedRuntime.hpp"
47
48 CompiledMethod::CompiledMethod(Method* method, const char* name, CompilerType type, const CodeBlobLayout& layout,
49 int frame_complete_offset, int frame_size, ImmutableOopMapSet* oop_maps,
50 bool caller_must_gc_arguments)
51 : CodeBlob(name, type, layout, frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),
52 _mark_for_deoptimization_status(not_marked),
53 _method(method),
54 _gc_data(NULL)
55 {
56 init_defaults();
57 }
58
59 CompiledMethod::CompiledMethod(Method* method, const char* name, CompilerType type, int size,
60 int header_size, CodeBuffer* cb, int frame_complete_offset, int frame_size,
61 OopMapSet* oop_maps, bool caller_must_gc_arguments)
62 : CodeBlob(name, type, CodeBlobLayout((address) this, size, header_size, cb), cb,
63 frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),
64 _mark_for_deoptimization_status(not_marked),
65 _method(method),
66 _gc_data(NULL)
67 {
68 init_defaults();
69 }
70
71 void CompiledMethod::init_defaults() {
72 _has_unsafe_access = 0;
73 _has_method_handle_invokes = 0;
74 _lazy_critical_native = 0;
75 _has_wide_vectors = 0;
76 }
77
78 bool CompiledMethod::is_method_handle_return(address return_pc) {
79 if (!has_method_handle_invokes()) return false;
80 PcDesc* pd = pc_desc_at(return_pc);
81 if (pd == NULL)
82 return false;
83 return pd->is_method_handle_invoke();
84 }
85
86 // Returns a string version of the method state.
87 const char* CompiledMethod::state() const {
88 int state = get_state();
89 switch (state) {
90 case not_installed:
91 return "not installed";
92 case in_use:
93 return "in use";
94 case not_used:
95 return "not_used";
96 case not_entrant:
97 return "not_entrant";
98 case zombie:
99 return "zombie";
100 case unloaded:
101 return "unloaded";
102 default:
103 fatal("unexpected method state: %d", state);
104 return NULL;
105 }
106 }
107
108 //-----------------------------------------------------------------------------
109 void CompiledMethod::mark_for_deoptimization(bool inc_recompile_counts) {
110 MutexLocker ml(CompiledMethod_lock->owned_by_self() ? NULL : CompiledMethod_lock,
111 Mutex::_no_safepoint_check_flag);
112 _mark_for_deoptimization_status = (inc_recompile_counts ? deoptimize : deoptimize_noupdate);
113 }
114
115 //-----------------------------------------------------------------------------
116
117 ExceptionCache* CompiledMethod::exception_cache_acquire() const {
118 return Atomic::load_acquire(&_exception_cache);
119 }
120
121 void CompiledMethod::add_exception_cache_entry(ExceptionCache* new_entry) {
122 assert(ExceptionCache_lock->owned_by_self(),"Must hold the ExceptionCache_lock");
123 assert(new_entry != NULL,"Must be non null");
124 assert(new_entry->next() == NULL, "Must be null");
125
126 for (;;) {
127 ExceptionCache *ec = exception_cache();
128 if (ec != NULL) {
129 Klass* ex_klass = ec->exception_type();
130 if (!ex_klass->is_loader_alive()) {
131 // We must guarantee that entries are not inserted with new next pointer
132 // edges to ExceptionCache entries with dead klasses, due to bad interactions
133 // with concurrent ExceptionCache cleanup. Therefore, the inserts roll
134 // the head pointer forward to the first live ExceptionCache, so that the new
135 // next pointers always point at live ExceptionCaches, that are not removed due
136 // to concurrent ExceptionCache cleanup.
137 ExceptionCache* next = ec->next();
138 if (Atomic::cmpxchg(&_exception_cache, ec, next) == ec) {
139 CodeCache::release_exception_cache(ec);
140 }
141 continue;
142 }
143 ec = exception_cache();
144 if (ec != NULL) {
145 new_entry->set_next(ec);
146 }
147 }
148 if (Atomic::cmpxchg(&_exception_cache, ec, new_entry) == ec) {
149 return;
150 }
151 }
152 }
153
154 void CompiledMethod::clean_exception_cache() {
155 // For each nmethod, only a single thread may call this cleanup function
156 // at the same time, whether called in STW cleanup or concurrent cleanup.
157 // Note that if the GC is processing exception cache cleaning in a concurrent phase,
158 // then a single writer may contend with cleaning up the head pointer to the
159 // first ExceptionCache node that has a Klass* that is alive. That is fine,
160 // as long as there is no concurrent cleanup of next pointers from concurrent writers.
161 // And the concurrent writers do not clean up next pointers, only the head.
162 // Also note that concurent readers will walk through Klass* pointers that are not
163 // alive. That does not cause ABA problems, because Klass* is deleted after
164 // a handshake with all threads, after all stale ExceptionCaches have been
165 // unlinked. That is also when the CodeCache::exception_cache_purge_list()
166 // is deleted, with all ExceptionCache entries that were cleaned concurrently.
167 // That similarly implies that CAS operations on ExceptionCache entries do not
168 // suffer from ABA problems as unlinking and deletion is separated by a global
169 // handshake operation.
170 ExceptionCache* prev = NULL;
171 ExceptionCache* curr = exception_cache_acquire();
172
173 while (curr != NULL) {
174 ExceptionCache* next = curr->next();
175
176 if (!curr->exception_type()->is_loader_alive()) {
177 if (prev == NULL) {
178 // Try to clean head; this is contended by concurrent inserts, that
179 // both lazily clean the head, and insert entries at the head. If
180 // the CAS fails, the operation is restarted.
181 if (Atomic::cmpxchg(&_exception_cache, curr, next) != curr) {
182 prev = NULL;
183 curr = exception_cache_acquire();
184 continue;
185 }
186 } else {
187 // It is impossible to during cleanup connect the next pointer to
188 // an ExceptionCache that has not been published before a safepoint
189 // prior to the cleanup. Therefore, release is not required.
190 prev->set_next(next);
191 }
192 // prev stays the same.
193
194 CodeCache::release_exception_cache(curr);
195 } else {
196 prev = curr;
197 }
198
199 curr = next;
200 }
201 }
202
203 // public method for accessing the exception cache
204 // These are the public access methods.
205 address CompiledMethod::handler_for_exception_and_pc(Handle exception, address pc) {
206 // We never grab a lock to read the exception cache, so we may
207 // have false negatives. This is okay, as it can only happen during
208 // the first few exception lookups for a given nmethod.
209 ExceptionCache* ec = exception_cache_acquire();
210 while (ec != NULL) {
211 address ret_val;
212 if ((ret_val = ec->match(exception,pc)) != NULL) {
213 return ret_val;
214 }
215 ec = ec->next();
216 }
217 return NULL;
218 }
219
220 void CompiledMethod::add_handler_for_exception_and_pc(Handle exception, address pc, address handler) {
221 // There are potential race conditions during exception cache updates, so we
222 // must own the ExceptionCache_lock before doing ANY modifications. Because
223 // we don't lock during reads, it is possible to have several threads attempt
224 // to update the cache with the same data. We need to check for already inserted
225 // copies of the current data before adding it.
226
227 MutexLocker ml(ExceptionCache_lock);
228 ExceptionCache* target_entry = exception_cache_entry_for_exception(exception);
229
230 if (target_entry == NULL || !target_entry->add_address_and_handler(pc,handler)) {
231 target_entry = new ExceptionCache(exception,pc,handler);
232 add_exception_cache_entry(target_entry);
233 }
234 }
235
236 // private method for handling exception cache
237 // These methods are private, and used to manipulate the exception cache
238 // directly.
239 ExceptionCache* CompiledMethod::exception_cache_entry_for_exception(Handle exception) {
240 ExceptionCache* ec = exception_cache_acquire();
241 while (ec != NULL) {
242 if (ec->match_exception_with_space(exception)) {
243 return ec;
244 }
245 ec = ec->next();
246 }
247 return NULL;
248 }
249
250 //-------------end of code for ExceptionCache--------------
251
252 bool CompiledMethod::is_at_poll_return(address pc) {
253 RelocIterator iter(this, pc, pc+1);
254 while (iter.next()) {
255 if (iter.type() == relocInfo::poll_return_type)
256 return true;
257 }
258 return false;
259 }
260
261
262 bool CompiledMethod::is_at_poll_or_poll_return(address pc) {
263 RelocIterator iter(this, pc, pc+1);
264 while (iter.next()) {
265 relocInfo::relocType t = iter.type();
266 if (t == relocInfo::poll_return_type || t == relocInfo::poll_type)
267 return true;
268 }
269 return false;
270 }
271
272 void CompiledMethod::verify_oop_relocations() {
273 // Ensure sure that the code matches the current oop values
274 RelocIterator iter(this, NULL, NULL);
275 while (iter.next()) {
276 if (iter.type() == relocInfo::oop_type) {
277 oop_Relocation* reloc = iter.oop_reloc();
278 if (!reloc->oop_is_immediate()) {
279 reloc->verify_oop_relocation();
280 }
281 }
282 }
283 }
284
285
286 ScopeDesc* CompiledMethod::scope_desc_at(address pc) {
287 PcDesc* pd = pc_desc_at(pc);
288 guarantee(pd != NULL, "scope must be present");
289 return new ScopeDesc(this, pd->scope_decode_offset(),
290 pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),
291 pd->return_oop());
292 }
293
294 ScopeDesc* CompiledMethod::scope_desc_near(address pc) {
295 PcDesc* pd = pc_desc_near(pc);
296 guarantee(pd != NULL, "scope must be present");
297 return new ScopeDesc(this, pd->scope_decode_offset(),
298 pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),
299 pd->return_oop());
300 }
301
302 address CompiledMethod::oops_reloc_begin() const {
303 // If the method is not entrant or zombie then a JMP is plastered over the
304 // first few bytes. If an oop in the old code was there, that oop
305 // should not get GC'd. Skip the first few bytes of oops on
306 // not-entrant methods.
307 if (frame_complete_offset() != CodeOffsets::frame_never_safe &&
308 code_begin() + frame_complete_offset() >
309 verified_entry_point() + NativeJump::instruction_size)
310 {
311 // If we have a frame_complete_offset after the native jump, then there
312 // is no point trying to look for oops before that. This is a requirement
313 // for being allowed to scan oops concurrently.
314 return code_begin() + frame_complete_offset();
315 }
316
317 // It is not safe to read oops concurrently using entry barriers, if their
318 // location depend on whether the nmethod is entrant or not.
319 assert(BarrierSet::barrier_set()->barrier_set_nmethod() == NULL, "Not safe oop scan");
320
321 address low_boundary = verified_entry_point();
322 if (!is_in_use() && is_nmethod()) {
323 low_boundary += NativeJump::instruction_size;
324 // %%% Note: On SPARC we patch only a 4-byte trap, not a full NativeJump.
325 // This means that the low_boundary is going to be a little too high.
326 // This shouldn't matter, since oops of non-entrant methods are never used.
327 // In fact, why are we bothering to look at oops in a non-entrant method??
328 }
329 return low_boundary;
330 }
331
332 int CompiledMethod::verify_icholder_relocations() {
333 ResourceMark rm;
334 int count = 0;
335
336 RelocIterator iter(this);
337 while(iter.next()) {
338 if (iter.type() == relocInfo::virtual_call_type) {
339 if (CompiledIC::is_icholder_call_site(iter.virtual_call_reloc(), this)) {
340 CompiledIC *ic = CompiledIC_at(&iter);
341 if (TraceCompiledIC) {
342 tty->print("noticed icholder " INTPTR_FORMAT " ", p2i(ic->cached_icholder()));
343 ic->print();
344 }
345 assert(ic->cached_icholder() != NULL, "must be non-NULL");
346 count++;
347 }
348 }
349 }
350
351 return count;
352 }
353
354 // Method that knows how to preserve outgoing arguments at call. This method must be
355 // called with a frame corresponding to a Java invoke
356 void CompiledMethod::preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map, OopClosure* f) {
357 if (method() != NULL && !method()->is_native()) {
358 address pc = fr.pc();
359 SimpleScopeDesc ssd(this, pc);
360 Bytecode_invoke call(methodHandle(Thread::current(), ssd.method()), ssd.bci());
361 bool has_receiver = call.has_receiver();
362 bool has_appendix = call.has_appendix();
363 Symbol* signature = call.signature();
364
365 // The method attached by JIT-compilers should be used, if present.
366 // Bytecode can be inaccurate in such case.
367 Method* callee = attached_method_before_pc(pc);
368 if (callee != NULL) {
369 has_receiver = !(callee->access_flags().is_static());
370 has_appendix = false;
371 signature = callee->signature();
372 }
373
374 fr.oops_compiled_arguments_do(signature, has_receiver, has_appendix, reg_map, f);
375 }
376 }
377
378 Method* CompiledMethod::attached_method(address call_instr) {
379 assert(code_contains(call_instr), "not part of the nmethod");
380 RelocIterator iter(this, call_instr, call_instr + 1);
381 while (iter.next()) {
382 if (iter.addr() == call_instr) {
383 switch(iter.type()) {
384 case relocInfo::static_call_type: return iter.static_call_reloc()->method_value();
385 case relocInfo::opt_virtual_call_type: return iter.opt_virtual_call_reloc()->method_value();
386 case relocInfo::virtual_call_type: return iter.virtual_call_reloc()->method_value();
387 default: break;
388 }
389 }
390 }
391 return NULL; // not found
392 }
393
394 Method* CompiledMethod::attached_method_before_pc(address pc) {
395 if (NativeCall::is_call_before(pc)) {
396 NativeCall* ncall = nativeCall_before(pc);
397 return attached_method(ncall->instruction_address());
398 }
399 return NULL; // not a call
400 }
401
402 void CompiledMethod::clear_inline_caches() {
403 assert(SafepointSynchronize::is_at_safepoint(), "cleaning of IC's only allowed at safepoint");
404 if (is_zombie()) {
405 return;
406 }
407
408 RelocIterator iter(this);
409 while (iter.next()) {
410 iter.reloc()->clear_inline_cache();
411 }
412 }
413
414 // Clear IC callsites, releasing ICStubs of all compiled ICs
415 // as well as any associated CompiledICHolders.
416 void CompiledMethod::clear_ic_callsites() {
417 assert(CompiledICLocker::is_safe(this), "mt unsafe call");
418 ResourceMark rm;
419 RelocIterator iter(this);
420 while(iter.next()) {
421 if (iter.type() == relocInfo::virtual_call_type) {
422 CompiledIC* ic = CompiledIC_at(&iter);
423 ic->set_to_clean(false);
424 }
425 }
426 }
427
428 #ifdef ASSERT
429 // Check class_loader is alive for this bit of metadata.
430 class CheckClass : public MetadataClosure {
431 void do_metadata(Metadata* md) {
432 Klass* klass = NULL;
433 if (md->is_klass()) {
434 klass = ((Klass*)md);
435 } else if (md->is_method()) {
436 klass = ((Method*)md)->method_holder();
437 } else if (md->is_methodData()) {
438 klass = ((MethodData*)md)->method()->method_holder();
439 } else {
440 md->print();
441 ShouldNotReachHere();
442 }
443 assert(klass->is_loader_alive(), "must be alive");
444 }
445 };
446 #endif // ASSERT
447
448
449 bool CompiledMethod::clean_ic_if_metadata_is_dead(CompiledIC *ic) {
450 if (ic->is_clean()) {
451 return true;
452 }
453 if (ic->is_icholder_call()) {
454 // The only exception is compiledICHolder metdata which may
455 // yet be marked below. (We check this further below).
456 CompiledICHolder* cichk_metdata = ic->cached_icholder();
457
458 if (cichk_metdata->is_loader_alive()) {
459 return true;
460 }
461 } else {
462 Metadata* ic_metdata = ic->cached_metadata();
463 if (ic_metdata != NULL) {
464 if (ic_metdata->is_klass()) {
465 if (((Klass*)ic_metdata)->is_loader_alive()) {
466 return true;
467 }
468 } else if (ic_metdata->is_method()) {
469 Method* method = (Method*)ic_metdata;
470 assert(!method->is_old(), "old method should have been cleaned");
471 if (method->method_holder()->is_loader_alive()) {
472 return true;
473 }
474 } else {
475 ShouldNotReachHere();
476 }
477 }
478 }
479
480 return ic->set_to_clean();
481 }
482
483 // Clean references to unloaded nmethods at addr from this one, which is not unloaded.
484 template <class CompiledICorStaticCall>
485 static bool clean_if_nmethod_is_unloaded(CompiledICorStaticCall *ic, address addr, CompiledMethod* from,
486 bool clean_all) {
487 // Ok, to lookup references to zombies here
488 CodeBlob *cb = CodeCache::find_blob_unsafe(addr);
489 CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;
490 if (nm != NULL) {
491 // Clean inline caches pointing to both zombie and not_entrant methods
492 if (clean_all || !nm->is_in_use() || nm->is_unloading() || (nm->method()->code() != nm)) {
493 // Inline cache cleaning should only be initiated on CompiledMethods that have been
494 // observed to be is_alive(). However, with concurrent code cache unloading, it is
495 // possible that by now, the state has become !is_alive. This can happen in two ways:
496 // 1) It can be racingly flipped to unloaded if the nmethod // being cleaned (from the
497 // sweeper) is_unloading(). This is fine, because if that happens, then the inline
498 // caches have already been cleaned under the same CompiledICLocker that we now hold during
499 // inline cache cleaning, and we will simply walk the inline caches again, and likely not
500 // find much of interest to clean. However, this race prevents us from asserting that the
501 // nmethod is_alive(). The is_unloading() function is completely monotonic; once set due
502 // to an oop dying, it remains set forever until freed. Because of that, all unloaded
503 // nmethods are is_unloading(), but notably, an unloaded nmethod may also subsequently
504 // become zombie (when the sweeper converts it to zombie).
505 // 2) It can be racingly flipped to zombie if the nmethod being cleaned (by the concurrent
506 // GC) cleans a zombie nmethod that is concurrently made zombie by the sweeper. In this
507 // scenario, the sweeper will first transition the nmethod to zombie, and then when
508 // unregistering from the GC, it will wait until the GC is done. The GC will then clean
509 // the inline caches *with IC stubs*, even though no IC stubs are needed. This is fine,
510 // as long as the IC stubs are guaranteed to be released until the next safepoint, where
511 // IC finalization requires live IC stubs to not be associated with zombie nmethods.
512 // This is guaranteed, because the sweeper does not have a single safepoint check until
513 // after it completes the whole transition function; it will wake up after the GC is
514 // done with concurrent code cache cleaning (which blocks out safepoints using the
515 // suspendible threads set), and then call clear_ic_callsites, which will release the
516 // associated IC stubs, before a subsequent safepoint poll can be reached. This
517 // guarantees that the spuriously created IC stubs are released appropriately before
518 // IC finalization in a safepoint gets to run. Therefore, this race is fine. This is also
519 // valid in a scenario where an inline cache of a zombie nmethod gets a spurious IC stub,
520 // and then when cleaning another inline cache, fails to request an IC stub because we
521 // exhausted the IC stub buffer. In this scenario, the GC will request a safepoint after
522 // yielding the suspendible therad set, effectively unblocking safepoints. Before such
523 // a safepoint can be reached, the sweeper similarly has to wake up, clear the IC stubs,
524 // and reach the next safepoint poll, after the whole transition function has completed.
525 // Due to the various races that can cause an nmethod to first be is_alive() and then
526 // racingly become !is_alive(), it is unfortunately not possible to assert the nmethod
527 // is_alive(), !is_unloaded() or !is_zombie() here.
528 if (!ic->set_to_clean(!from->is_unloading())) {
529 return false;
530 }
531 assert(ic->is_clean(), "nmethod " PTR_FORMAT "not clean %s", p2i(from), from->method()->name_and_sig_as_C_string());
532 }
533 }
534 return true;
535 }
536
537 static bool clean_if_nmethod_is_unloaded(CompiledIC *ic, CompiledMethod* from,
538 bool clean_all) {
539 return clean_if_nmethod_is_unloaded(ic, ic->ic_destination(), from, clean_all);
540 }
541
542 static bool clean_if_nmethod_is_unloaded(CompiledStaticCall *csc, CompiledMethod* from,
543 bool clean_all) {
544 return clean_if_nmethod_is_unloaded(csc, csc->destination(), from, clean_all);
545 }
546
547 // Cleans caches in nmethods that point to either classes that are unloaded
548 // or nmethods that are unloaded.
549 //
550 // Can be called either in parallel by G1 currently or after all
551 // nmethods are unloaded. Return postponed=true in the parallel case for
552 // inline caches found that point to nmethods that are not yet visited during
553 // the do_unloading walk.
554 bool CompiledMethod::unload_nmethod_caches(bool unloading_occurred) {
555 ResourceMark rm;
556
557 // Exception cache only needs to be called if unloading occurred
558 if (unloading_occurred) {
559 clean_exception_cache();
560 }
561
562 if (!cleanup_inline_caches_impl(unloading_occurred, false)) {
563 return false;
564 }
565
566 #ifdef ASSERT
567 // Check that the metadata embedded in the nmethod is alive
568 CheckClass check_class;
569 metadata_do(&check_class);
570 #endif
571 return true;
572 }
573
574 void CompiledMethod::run_nmethod_entry_barrier() {
575 BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
576 if (bs_nm != NULL) {
577 // We want to keep an invariant that nmethods found through iterations of a Thread's
578 // nmethods found in safepoints have gone through an entry barrier and are not armed.
579 // By calling this nmethod entry barrier, it plays along and acts
580 // like any other nmethod found on the stack of a thread (fewer surprises).
581 nmethod* nm = as_nmethod_or_null();
582 if (nm != NULL) {
583 bool alive = bs_nm->nmethod_entry_barrier(nm);
584 assert(alive, "should be alive");
585 }
586 }
587 }
588
589 void CompiledMethod::cleanup_inline_caches(bool clean_all) {
590 for (;;) {
591 ICRefillVerifier ic_refill_verifier;
592 { CompiledICLocker ic_locker(this);
593 if (cleanup_inline_caches_impl(false, clean_all)) {
594 return;
595 }
596 }
597 // Call this nmethod entry barrier from the sweeper.
598 run_nmethod_entry_barrier();
599 InlineCacheBuffer::refill_ic_stubs();
600 }
601 }
602
603 // Called to clean up after class unloading for live nmethods and from the sweeper
604 // for all methods.
605 bool CompiledMethod::cleanup_inline_caches_impl(bool unloading_occurred, bool clean_all) {
606 assert(CompiledICLocker::is_safe(this), "mt unsafe call");
607 ResourceMark rm;
608
609 // Find all calls in an nmethod and clear the ones that point to non-entrant,
610 // zombie and unloaded nmethods.
611 RelocIterator iter(this, oops_reloc_begin());
612 bool is_in_static_stub = false;
613 while(iter.next()) {
614
615 switch (iter.type()) {
616
617 case relocInfo::virtual_call_type:
618 if (unloading_occurred) {
619 // If class unloading occurred we first clear ICs where the cached metadata
620 // is referring to an unloaded klass or method.
621 if (!clean_ic_if_metadata_is_dead(CompiledIC_at(&iter))) {
622 return false;
623 }
624 }
625
626 if (!clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, clean_all)) {
627 return false;
628 }
629 break;
630
631 case relocInfo::opt_virtual_call_type:
632 if (!clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), this, clean_all)) {
633 return false;
634 }
635 break;
636
637 case relocInfo::static_call_type:
638 if (!clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), this, clean_all)) {
639 return false;
640 }
641 break;
642
643 case relocInfo::static_stub_type: {
644 is_in_static_stub = true;
645 break;
646 }
647
648 case relocInfo::metadata_type: {
649 // Only the metadata relocations contained in static/opt virtual call stubs
650 // contains the Method* passed to c2i adapters. It is the only metadata
651 // relocation that needs to be walked, as it is the one metadata relocation
652 // that violates the invariant that all metadata relocations have an oop
653 // in the compiled method (due to deferred resolution and code patching).
654
655 // This causes dead metadata to remain in compiled methods that are not
656 // unloading. Unless these slippery metadata relocations of the static
657 // stubs are at least cleared, subsequent class redefinition operations
658 // will access potentially free memory, and JavaThread execution
659 // concurrent to class unloading may call c2i adapters with dead methods.
660 if (!is_in_static_stub) {
661 // The first metadata relocation after a static stub relocation is the
662 // metadata relocation of the static stub used to pass the Method* to
663 // c2i adapters.
664 continue;
665 }
666 is_in_static_stub = false;
667 if (is_unloading()) {
668 // If the nmethod itself is dying, then it may point at dead metadata.
669 // Nobody should follow that metadata; it is strictly unsafe.
670 continue;
671 }
672 metadata_Relocation* r = iter.metadata_reloc();
673 Metadata* md = r->metadata_value();
674 if (md != NULL && md->is_method()) {
675 Method* method = static_cast<Method*>(md);
676 if (!method->method_holder()->is_loader_alive()) {
677 Atomic::store(r->metadata_addr(), (Method*)NULL);
678
679 if (!r->metadata_is_immediate()) {
680 r->fix_metadata_relocation();
681 }
682 }
683 }
684 break;
685 }
686
687 default:
688 break;
689 }
690 }
691
692 return true;
693 }
694
695 // Iterating over all nmethods, e.g. with the help of CodeCache::nmethods_do(fun) was found
696 // to not be inherently safe. There is a chance that fields are seen which are not properly
697 // initialized. This happens despite the fact that nmethods_do() asserts the CodeCache_lock
698 // to be held.
699 // To bundle knowledge about necessary checks in one place, this function was introduced.
700 // It is not claimed that these checks are sufficient, but they were found to be necessary.
701 bool CompiledMethod::nmethod_access_is_safe(nmethod* nm) {
702 Method* method = (nm == NULL) ? NULL : nm->method(); // nm->method() may be uninitialized, i.e. != NULL, but invalid
703 return (nm != NULL) && (method != NULL) && (method->signature() != NULL) &&
704 !nm->is_zombie() && !nm->is_not_installed() &&
705 os::is_readable_pointer(method) &&
706 os::is_readable_pointer(method->constants()) &&
707 os::is_readable_pointer(method->signature());
708 }
709
710 address CompiledMethod::continuation_for_implicit_exception(address pc, bool for_div0_check) {
711 // Exception happened outside inline-cache check code => we are inside
712 // an active nmethod => use cpc to determine a return address
713 int exception_offset = pc - code_begin();
714 int cont_offset = ImplicitExceptionTable(this).continuation_offset( exception_offset );
715 #ifdef ASSERT
716 if (cont_offset == 0) {
717 Thread* thread = Thread::current();
718 ResetNoHandleMark rnm; // Might be called from LEAF/QUICK ENTRY
719 HandleMark hm(thread);
720 ResourceMark rm(thread);
721 CodeBlob* cb = CodeCache::find_blob(pc);
722 assert(cb != NULL && cb == this, "");
723 ttyLocker ttyl;
724 tty->print_cr("implicit exception happened at " INTPTR_FORMAT, p2i(pc));
725 print();
726 method()->print_codes();
727 print_code();
728 print_pcs();
729 }
730 #endif
731 if (cont_offset == 0) {
732 // Let the normal error handling report the exception
733 return NULL;
734 }
735 if (cont_offset == exception_offset) {
736 #if INCLUDE_JVMCI
737 Deoptimization::DeoptReason deopt_reason = for_div0_check ? Deoptimization::Reason_div0_check : Deoptimization::Reason_null_check;
738 JavaThread *thread = JavaThread::current();
739 thread->set_jvmci_implicit_exception_pc(pc);
740 thread->set_pending_deoptimization(Deoptimization::make_trap_request(deopt_reason,
741 Deoptimization::Action_reinterpret));
742 return (SharedRuntime::deopt_blob()->implicit_exception_uncommon_trap());
743 #else
744 ShouldNotReachHere();
745 #endif
746 }
747 return code_begin() + cont_offset;
748 }
749
750 class HasEvolDependency : public MetadataClosure {
751 bool _has_evol_dependency;
752 public:
753 HasEvolDependency() : _has_evol_dependency(false) {}
754 void do_metadata(Metadata* md) {
755 if (md->is_method()) {
756 Method* method = (Method*)md;
757 if (method->is_old()) {
758 _has_evol_dependency = true;
759 }
760 }
761 }
762 bool has_evol_dependency() const { return _has_evol_dependency; }
763 };
764
765 bool CompiledMethod::has_evol_metadata() {
766 // Check the metadata in relocIter and CompiledIC and also deoptimize
767 // any nmethod that has reference to old methods.
768 HasEvolDependency check_evol;
769 metadata_do(&check_evol);
770 if (check_evol.has_evol_dependency() && log_is_enabled(Debug, redefine, class, nmethod)) {
771 ResourceMark rm;
772 log_debug(redefine, class, nmethod)
773 ("Found evol dependency of nmethod %s.%s(%s) compile_id=%d on in nmethod metadata",
774 _method->method_holder()->external_name(),
775 _method->name()->as_C_string(),
776 _method->signature()->as_C_string(),
777 compile_id());
778 }
779 return check_evol.has_evol_dependency();
780 }