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