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