1 /*

     2  * Copyright (c) 2015, 2017, 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 "prims/methodHandles.hpp"

    31 #include "interpreter/bytecode.hpp"

    32 #include "memory/resourceArea.hpp"

    33 #include "runtime/mutexLocker.hpp"

    34 

    35 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)

    36   : CodeBlob(name, type, layout, frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),

    37   _method(method), _mark_for_deoptimization_status(not_marked) {

    38   init_defaults();

    39 }

    40 

    41 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)

    42   : CodeBlob(name, type, CodeBlobLayout((address) this, size, header_size, cb), cb, frame_complete_offset, frame_size, oop_maps, caller_must_gc_arguments),

    43   _method(method), _mark_for_deoptimization_status(not_marked) {

    44   init_defaults();

    45 }

    46 

    47 void CompiledMethod::init_defaults() {

    48   _has_unsafe_access          = 0;

    49   _has_method_handle_invokes  = 0;

    50   _lazy_critical_native       = 0;

    51   _has_wide_vectors           = 0;

    52   _unloading_clock            = 0;

    53 }

    54 

    55 bool CompiledMethod::is_method_handle_return(address return_pc) {

    56   if (!has_method_handle_invokes())  return false;

    57   PcDesc* pd = pc_desc_at(return_pc);

    58   if (pd == NULL)

    59     return false;

    60   return pd->is_method_handle_invoke();

    61 }

    62 

    63 // Returns a string version of the method state.

    64 const char* CompiledMethod::state() const {

    65   int state = get_state();

    66   switch (state) {

    67   case in_use:

    68     return "in use";

    69   case not_used:

    70     return "not_used";

    71   case not_entrant:

    72     return "not_entrant";

    73   case zombie:

    74     return "zombie";

    75   case unloaded:

    76     return "unloaded";

    77   default:

    78     fatal("unexpected method state: %d", state);

    79     return NULL;

    80   }

    81 }

    82 

    83 //-----------------------------------------------------------------------------

    84 

    85 void CompiledMethod::add_exception_cache_entry(ExceptionCache* new_entry) {

    86   assert(ExceptionCache_lock->owned_by_self(),"Must hold the ExceptionCache_lock");

    87   assert(new_entry != NULL,"Must be non null");

    88   assert(new_entry->next() == NULL, "Must be null");

    89 

    90   ExceptionCache *ec = exception_cache();

    91   if (ec != NULL) {

    92     new_entry->set_next(ec);

    93   }

    94   release_set_exception_cache(new_entry);

    95 }

    96 

    97 void CompiledMethod::clean_exception_cache(BoolObjectClosure* is_alive) {

    98   ExceptionCache* prev = NULL;

    99   ExceptionCache* curr = exception_cache();

   100 

   101   while (curr != NULL) {

   102     ExceptionCache* next = curr->next();

   103 

   104     Klass* ex_klass = curr->exception_type();

   105     if (ex_klass != NULL && !ex_klass->is_loader_alive(is_alive)) {

   106       if (prev == NULL) {

   107         set_exception_cache(next);

   108       } else {

   109         prev->set_next(next);

   110       }

   111       delete curr;

   112       // prev stays the same.

   113     } else {

   114       prev = curr;

   115     }

   116 

   117     curr = next;

   118   }

   119 }

   120 

   121 // public method for accessing the exception cache

   122 // These are the public access methods.

   123 address CompiledMethod::handler_for_exception_and_pc(Handle exception, address pc) {

   124   // We never grab a lock to read the exception cache, so we may

   125   // have false negatives. This is okay, as it can only happen during

   126   // the first few exception lookups for a given nmethod.

   127   ExceptionCache* ec = exception_cache();

   128   while (ec != NULL) {

   129     address ret_val;

   130     if ((ret_val = ec->match(exception,pc)) != NULL) {

   131       return ret_val;

   132     }

   133     ec = ec->next();

   134   }

   135   return NULL;

   136 }

   137 

   138 void CompiledMethod::add_handler_for_exception_and_pc(Handle exception, address pc, address handler) {

   139   // There are potential race conditions during exception cache updates, so we

   140   // must own the ExceptionCache_lock before doing ANY modifications. Because

   141   // we don't lock during reads, it is possible to have several threads attempt

   142   // to update the cache with the same data. We need to check for already inserted

   143   // copies of the current data before adding it.

   144 

   145   MutexLocker ml(ExceptionCache_lock);

   146   ExceptionCache* target_entry = exception_cache_entry_for_exception(exception);

   147 

   148   if (target_entry == NULL || !target_entry->add_address_and_handler(pc,handler)) {

   149     target_entry = new ExceptionCache(exception,pc,handler);

   150     add_exception_cache_entry(target_entry);

   151   }

   152 }

   153 

   154 //-------------end of code for ExceptionCache--------------

   155 

   156 // private method for handling exception cache

   157 // These methods are private, and used to manipulate the exception cache

   158 // directly.

   159 ExceptionCache* CompiledMethod::exception_cache_entry_for_exception(Handle exception) {

   160   ExceptionCache* ec = exception_cache();

   161   while (ec != NULL) {

   162     if (ec->match_exception_with_space(exception)) {

   163       return ec;

   164     }

   165     ec = ec->next();

   166   }

   167   return NULL;

   168 }

   169 

   170 bool CompiledMethod::is_at_poll_return(address pc) {

   171   RelocIterator iter(this, pc, pc+1);

   172   while (iter.next()) {

   173     if (iter.type() == relocInfo::poll_return_type)

   174       return true;

   175   }

   176   return false;

   177 }

   178 

   179 

   180 bool CompiledMethod::is_at_poll_or_poll_return(address pc) {

   181   RelocIterator iter(this, pc, pc+1);

   182   while (iter.next()) {

   183     relocInfo::relocType t = iter.type();

   184     if (t == relocInfo::poll_return_type || t == relocInfo::poll_type)

   185       return true;

   186   }

   187   return false;

   188 }

   189 

   190 void CompiledMethod::verify_oop_relocations() {

   191   // Ensure sure that the code matches the current oop values

   192   RelocIterator iter(this, NULL, NULL);

   193   while (iter.next()) {

   194     if (iter.type() == relocInfo::oop_type) {

   195       oop_Relocation* reloc = iter.oop_reloc();

   196       if (!reloc->oop_is_immediate()) {

   197         reloc->verify_oop_relocation();

   198       }

   199     }

   200   }

   201 }

   202 

   203 

   204 ScopeDesc* CompiledMethod::scope_desc_at(address pc) {

   205   PcDesc* pd = pc_desc_at(pc);

   206   guarantee(pd != NULL, "scope must be present");

   207   return new ScopeDesc(this, pd->scope_decode_offset(),

   208                        pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),

   209                        pd->return_oop());

   210 }

   211 

   212 ScopeDesc* CompiledMethod::scope_desc_near(address pc) {

   213   PcDesc* pd = pc_desc_near(pc);

   214   guarantee(pd != NULL, "scope must be present");

   215   return new ScopeDesc(this, pd->scope_decode_offset(),

   216                        pd->obj_decode_offset(), pd->should_reexecute(), pd->rethrow_exception(),

   217                        pd->return_oop());

   218 }

   219 

   220 void CompiledMethod::cleanup_inline_caches(bool clean_all/*=false*/) {

   221   assert_locked_or_safepoint(CompiledIC_lock);

   222 

   223   // If the method is not entrant or zombie then a JMP is plastered over the

   224   // first few bytes.  If an oop in the old code was there, that oop

   225   // should not get GC'd.  Skip the first few bytes of oops on

   226   // not-entrant methods.

   227   address low_boundary = verified_entry_point();

   228   if (!is_in_use() && is_nmethod()) {

   229     low_boundary += NativeJump::instruction_size;

   230     // %%% Note:  On SPARC we patch only a 4-byte trap, not a full NativeJump.

   231     // This means that the low_boundary is going to be a little too high.

   232     // This shouldn't matter, since oops of non-entrant methods are never used.

   233     // In fact, why are we bothering to look at oops in a non-entrant method??

   234   }

   235 

   236   // Find all calls in an nmethod and clear the ones that point to non-entrant,

   237   // zombie and unloaded nmethods.

   238   ResourceMark rm;

   239   RelocIterator iter(this, low_boundary);

   240   while(iter.next()) {

   241     switch(iter.type()) {

   242       case relocInfo::virtual_call_type:

   243       case relocInfo::opt_virtual_call_type: {

   244         CompiledIC *ic = CompiledIC_at(&iter);

   245         // Ok, to lookup references to zombies here

   246         CodeBlob *cb = CodeCache::find_blob_unsafe(ic->ic_destination());

   247         if( cb != NULL && cb->is_compiled() ) {

   248           CompiledMethod* nm = cb->as_compiled_method();

   249           // Clean inline caches pointing to zombie, non-entrant and unloaded methods

   250           if (clean_all || !nm->is_in_use() || (nm->method()->code() != nm)) ic->set_to_clean(is_alive());

   251         }

   252         break;

   253       }

   254       case relocInfo::static_call_type: {

   255           CompiledStaticCall *csc = compiledStaticCall_at(iter.reloc());

   256           CodeBlob *cb = CodeCache::find_blob_unsafe(csc->destination());

   257           if( cb != NULL && cb->is_compiled() ) {

   258             CompiledMethod* cm = cb->as_compiled_method();

   259             // Clean inline caches pointing to zombie, non-entrant and unloaded methods

   260             if (clean_all || !cm->is_in_use() || (cm->method()->code() != cm)) {

   261               csc->set_to_clean();

   262             }

   263           }

   264         break;

   265       }

   266       default:

   267         break;

   268     }

   269   }

   270 }

   271 

   272 int CompiledMethod::verify_icholder_relocations() {

   273   ResourceMark rm;

   274   int count = 0;

   275 

   276   RelocIterator iter(this);

   277   while(iter.next()) {

   278     if (iter.type() == relocInfo::virtual_call_type) {

   279       if (CompiledIC::is_icholder_call_site(iter.virtual_call_reloc(), this)) {

   280         CompiledIC *ic = CompiledIC_at(&iter);

   281         if (TraceCompiledIC) {

   282           tty->print("noticed icholder " INTPTR_FORMAT " ", p2i(ic->cached_icholder()));

   283           ic->print();

   284         }

   285         assert(ic->cached_icholder() != NULL, "must be non-NULL");

   286         count++;

   287       }

   288     }

   289   }

   290 

   291   return count;

   292 }

   293 

   294 // Method that knows how to preserve outgoing arguments at call. This method must be

   295 // called with a frame corresponding to a Java invoke

   296 void CompiledMethod::preserve_callee_argument_oops(frame fr, const RegisterMap *reg_map, OopClosure* f) {

   297 #ifndef SHARK

   298   if (method() != NULL && !method()->is_native()) {

   299     address pc = fr.pc();

   300     SimpleScopeDesc ssd(this, pc);

   301     Bytecode_invoke call(ssd.method(), ssd.bci());

   302     bool has_receiver = call.has_receiver();

   303     bool has_appendix = call.has_appendix();

   304     Symbol* signature = call.signature();

   305 

   306     // The method attached by JIT-compilers should be used, if present.

   307     // Bytecode can be inaccurate in such case.

   308     Method* callee = attached_method_before_pc(pc);

   309     if (callee != NULL) {

   310       has_receiver = !(callee->access_flags().is_static());

   311       has_appendix = false;

   312       signature = callee->signature();

   313     }

   314 

   315     fr.oops_compiled_arguments_do(signature, has_receiver, has_appendix, reg_map, f);

   316   }

   317 #endif // !SHARK

   318 }

   319 

   320 Method* CompiledMethod::attached_method(address call_instr) {

   321   assert(code_contains(call_instr), "not part of the nmethod");

   322   RelocIterator iter(this, call_instr, call_instr + 1);

   323   while (iter.next()) {

   324     if (iter.addr() == call_instr) {

   325       switch(iter.type()) {

   326         case relocInfo::static_call_type:      return iter.static_call_reloc()->method_value();

   327         case relocInfo::opt_virtual_call_type: return iter.opt_virtual_call_reloc()->method_value();

   328         case relocInfo::virtual_call_type:     return iter.virtual_call_reloc()->method_value();

   329         default:                               break;

   330       }

   331     }

   332   }

   333   return NULL; // not found

   334 }

   335 

   336 Method* CompiledMethod::attached_method_before_pc(address pc) {

   337   if (NativeCall::is_call_before(pc)) {

   338     NativeCall* ncall = nativeCall_before(pc);

   339     return attached_method(ncall->instruction_address());

   340   }

   341   return NULL; // not a call

   342 }

   343 

   344 void CompiledMethod::clear_inline_caches() {

   345   assert(SafepointSynchronize::is_at_safepoint(), "cleaning of IC's only allowed at safepoint");

   346   if (is_zombie()) {

   347     return;

   348   }

   349 

   350   RelocIterator iter(this);

   351   while (iter.next()) {

   352     iter.reloc()->clear_inline_cache();

   353   }

   354 }

   355 

   356 // Clear ICStubs of all compiled ICs

   357 void CompiledMethod::clear_ic_stubs() {

   358   assert_locked_or_safepoint(CompiledIC_lock);

   359   RelocIterator iter(this);

   360   while(iter.next()) {

   361     if (iter.type() == relocInfo::virtual_call_type) {

   362       CompiledIC* ic = CompiledIC_at(&iter);

   363       ic->clear_ic_stub();

   364     }

   365   }

   366 }

   367 

   368 #ifdef ASSERT

   369 

   370 class CheckClass : AllStatic {

   371   static BoolObjectClosure* _is_alive;

   372 

   373   // Check class_loader is alive for this bit of metadata.

   374   static void check_class(Metadata* md) {

   375     Klass* klass = NULL;

   376     if (md->is_klass()) {

   377       klass = ((Klass*)md);

   378     } else if (md->is_method()) {

   379       klass = ((Method*)md)->method_holder();

   380     } else if (md->is_methodData()) {

   381       klass = ((MethodData*)md)->method()->method_holder();

   382     } else {

   383       md->print();

   384       ShouldNotReachHere();

   385     }

   386     assert(klass->is_loader_alive(_is_alive), "must be alive");

   387   }

   388  public:

   389   static void do_check_class(BoolObjectClosure* is_alive, CompiledMethod* nm) {

   390     assert(SafepointSynchronize::is_at_safepoint(), "this is only ok at safepoint");

   391     _is_alive = is_alive;

   392     nm->metadata_do(check_class);

   393   }

   394 };

   395 

   396 // This is called during a safepoint so can use static data

   397 BoolObjectClosure* CheckClass::_is_alive = NULL;

   398 #endif // ASSERT

   399 

   400 

   401 void CompiledMethod::clean_ic_if_metadata_is_dead(CompiledIC *ic, BoolObjectClosure *is_alive) {

   402   if (ic->is_icholder_call()) {

   403     // The only exception is compiledICHolder oops which may

   404     // yet be marked below. (We check this further below).

   405     CompiledICHolder* cichk_oop = ic->cached_icholder();

   406 

   407     if (cichk_oop->holder_method()->method_holder()->is_loader_alive(is_alive) &&

   408         cichk_oop->holder_klass()->is_loader_alive(is_alive)) {

   409       return;

   410     }

   411   } else {

   412     Metadata* ic_oop = ic->cached_metadata();

   413     if (ic_oop != NULL) {

   414       if (ic_oop->is_klass()) {

   415         if (((Klass*)ic_oop)->is_loader_alive(is_alive)) {

   416           return;

   417         }

   418       } else if (ic_oop->is_method()) {

   419         if (((Method*)ic_oop)->method_holder()->is_loader_alive(is_alive)) {

   420           return;

   421         }

   422       } else {

   423         ShouldNotReachHere();

   424       }

   425     }

   426   }

   427 

   428   ic->set_to_clean();

   429 }

   430 

   431 unsigned char CompiledMethod::_global_unloading_clock = 0;

   432 

   433 void CompiledMethod::increase_unloading_clock() {

   434   _global_unloading_clock++;

   435   if (_global_unloading_clock == 0) {

   436     // _nmethods are allocated with _unloading_clock == 0,

   437     // so 0 is never used as a clock value.

   438     _global_unloading_clock = 1;

   439   }

   440 }

   441 

   442 void CompiledMethod::set_unloading_clock(unsigned char unloading_clock) {

   443   OrderAccess::release_store((volatile jubyte*)&_unloading_clock, unloading_clock);

   444 }

   445 

   446 unsigned char CompiledMethod::unloading_clock() {

   447   return (unsigned char)OrderAccess::load_acquire((volatile jubyte*)&_unloading_clock);

   448 }

   449 

   450 // Processing of oop references should have been sufficient to keep

   451 // all strong references alive.  Any weak references should have been

   452 // cleared as well.  Visit all the metadata and ensure that it's

   453 // really alive.

   454 void CompiledMethod::verify_metadata_loaders(address low_boundary, BoolObjectClosure* is_alive) {

   455 #ifdef ASSERT

   456     RelocIterator iter(this, low_boundary);

   457     while (iter.next()) {

   458     // static_stub_Relocations may have dangling references to

   459     // Method*s so trim them out here.  Otherwise it looks like

   460     // compiled code is maintaining a link to dead metadata.

   461     address static_call_addr = NULL;

   462     if (iter.type() == relocInfo::opt_virtual_call_type) {

   463       CompiledIC* cic = CompiledIC_at(&iter);

   464       if (!cic->is_call_to_interpreted()) {

   465         static_call_addr = iter.addr();

   466       }

   467     } else if (iter.type() == relocInfo::static_call_type) {

   468       CompiledStaticCall* csc = compiledStaticCall_at(iter.reloc());

   469       if (!csc->is_call_to_interpreted()) {

   470         static_call_addr = iter.addr();

   471       }

   472     }

   473     if (static_call_addr != NULL) {

   474       RelocIterator sciter(this, low_boundary);

   475       while (sciter.next()) {

   476         if (sciter.type() == relocInfo::static_stub_type &&

   477             sciter.static_stub_reloc()->static_call() == static_call_addr) {

   478           sciter.static_stub_reloc()->clear_inline_cache();

   479         }

   480       }

   481     }

   482   }

   483   // Check that the metadata embedded in the nmethod is alive

   484   CheckClass::do_check_class(is_alive, this);

   485 #endif

   486 }

   487 

   488 // This is called at the end of the strong tracing/marking phase of a

   489 // GC to unload an nmethod if it contains otherwise unreachable

   490 // oops.

   491 

   492 void CompiledMethod::do_unloading(BoolObjectClosure* is_alive, bool unloading_occurred) {

   493   // Make sure the oop's ready to receive visitors

   494   assert(!is_zombie() && !is_unloaded(),

   495          "should not call follow on zombie or unloaded nmethod");

   496 

   497   // If the method is not entrant then a JMP is plastered over the

   498   // first few bytes.  If an oop in the old code was there, that oop

   499   // should not get GC'd.  Skip the first few bytes of oops on

   500   // not-entrant methods.

   501   address low_boundary = verified_entry_point();

   502   if (is_not_entrant()) {

   503     low_boundary += NativeJump::instruction_size;

   504     // %%% Note:  On SPARC we patch only a 4-byte trap, not a full NativeJump.

   505     // (See comment above.)

   506   }

   507 

   508   // The RedefineClasses() API can cause the class unloading invariant

   509   // to no longer be true. See jvmtiExport.hpp for details.

   510   // Also, leave a debugging breadcrumb in local flag.

   511   if (JvmtiExport::has_redefined_a_class()) {

   512     // This set of the unloading_occurred flag is done before the

   513     // call to post_compiled_method_unload() so that the unloading

   514     // of this nmethod is reported.

   515     unloading_occurred = true;

   516   }

   517 

   518   // Exception cache

   519   clean_exception_cache(is_alive);

   520 

   521   // If class unloading occurred we first iterate over all inline caches and

   522   // clear ICs where the cached oop is referring to an unloaded klass or method.

   523   // The remaining live cached oops will be traversed in the relocInfo::oop_type

   524   // iteration below.

   525   if (unloading_occurred) {

   526     RelocIterator iter(this, low_boundary);

   527     while(iter.next()) {

   528       if (iter.type() == relocInfo::virtual_call_type) {

   529         CompiledIC *ic = CompiledIC_at(&iter);

   530         clean_ic_if_metadata_is_dead(ic, is_alive);

   531       }

   532     }

   533   }

   534 

   535   if (do_unloading_oops(low_boundary, is_alive, unloading_occurred)) {

   536     return;

   537   }

   538 

   539 #if INCLUDE_JVMCI

   540   if (do_unloading_jvmci(is_alive, unloading_occurred)) {

   541     return;

   542   }

   543 #endif

   544 

   545   // Ensure that all metadata is still alive

   546   verify_metadata_loaders(low_boundary, is_alive);

   547 }

   548 

   549 template <class CompiledICorStaticCall>

   550 static bool clean_if_nmethod_is_unloaded(CompiledICorStaticCall *ic, address addr, BoolObjectClosure *is_alive, CompiledMethod* from) {

   551   // Ok, to lookup references to zombies here

   552   CodeBlob *cb = CodeCache::find_blob_unsafe(addr);

   553   CompiledMethod* nm = (cb != NULL) ? cb->as_compiled_method_or_null() : NULL;

   554   if (nm != NULL) {

   555     if (nm->unloading_clock() != CompiledMethod::global_unloading_clock()) {

   556       // The nmethod has not been processed yet.

   557       return true;

   558     }

   559 

   560     // Clean inline caches pointing to both zombie and not_entrant methods

   561     if (!nm->is_in_use() || (nm->method()->code() != nm)) {

   562       ic->set_to_clean();

   563       assert(ic->is_clean(), "nmethod " PTR_FORMAT "not clean %s", p2i(from), from->method()->name_and_sig_as_C_string());

   564     }

   565   }

   566 

   567   return false;

   568 }

   569 

   570 static bool clean_if_nmethod_is_unloaded(CompiledIC *ic, BoolObjectClosure *is_alive, CompiledMethod* from) {

   571   return clean_if_nmethod_is_unloaded(ic, ic->ic_destination(), is_alive, from);

   572 }

   573 

   574 static bool clean_if_nmethod_is_unloaded(CompiledStaticCall *csc, BoolObjectClosure *is_alive, CompiledMethod* from) {

   575   return clean_if_nmethod_is_unloaded(csc, csc->destination(), is_alive, from);

   576 }

   577 

   578 bool CompiledMethod::do_unloading_parallel(BoolObjectClosure* is_alive, bool unloading_occurred) {

   579   ResourceMark rm;

   580 

   581   // Make sure the oop's ready to receive visitors

   582   assert(!is_zombie() && !is_unloaded(),

   583          "should not call follow on zombie or unloaded nmethod");

   584 

   585   // If the method is not entrant then a JMP is plastered over the

   586   // first few bytes.  If an oop in the old code was there, that oop

   587   // should not get GC'd.  Skip the first few bytes of oops on

   588   // not-entrant methods.

   589   address low_boundary = verified_entry_point();

   590   if (is_not_entrant()) {

   591     low_boundary += NativeJump::instruction_size;

   592     // %%% Note:  On SPARC we patch only a 4-byte trap, not a full NativeJump.

   593     // (See comment above.)

   594   }

   595 

   596   // The RedefineClasses() API can cause the class unloading invariant

   597   // to no longer be true. See jvmtiExport.hpp for details.

   598   // Also, leave a debugging breadcrumb in local flag.

   599   if (JvmtiExport::has_redefined_a_class()) {

   600     // This set of the unloading_occurred flag is done before the

   601     // call to post_compiled_method_unload() so that the unloading

   602     // of this nmethod is reported.

   603     unloading_occurred = true;

   604   }

   605 

   606   // Exception cache

   607   clean_exception_cache(is_alive);

   608 

   609   bool postponed = false;

   610 

   611   RelocIterator iter(this, low_boundary);

   612   while(iter.next()) {

   613 

   614     switch (iter.type()) {

   615 

   616     case relocInfo::virtual_call_type:

   617       if (unloading_occurred) {

   618         // If class unloading occurred we first iterate over all inline caches and

   619         // clear ICs where the cached oop is referring to an unloaded klass or method.

   620         clean_ic_if_metadata_is_dead(CompiledIC_at(&iter), is_alive);

   621       }

   622 

   623       postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);

   624       break;

   625 

   626     case relocInfo::opt_virtual_call_type:

   627       postponed |= clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);

   628       break;

   629 

   630     case relocInfo::static_call_type:

   631       postponed |= clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), is_alive, this);

   632       break;

   633 

   634     case relocInfo::oop_type:

   635       // handled by do_unloading_oops below

   636       break;

   637 

   638     case relocInfo::metadata_type:

   639       break; // nothing to do.

   640 

   641     default:

   642       break;

   643     }

   644   }

   645 

   646   if (do_unloading_oops(low_boundary, is_alive, unloading_occurred)) {

   647     return postponed;

   648   }

   649 

   650 #if INCLUDE_JVMCI

   651   if (do_unloading_jvmci(is_alive, unloading_occurred)) {

   652     return postponed;

   653   }

   654 #endif

   655 

   656   // Ensure that all metadata is still alive

   657   verify_metadata_loaders(low_boundary, is_alive);

   658 

   659   return postponed;

   660 }

   661 

   662 void CompiledMethod::do_unloading_parallel_postponed(BoolObjectClosure* is_alive, bool unloading_occurred) {

   663   ResourceMark rm;

   664 

   665   // Make sure the oop's ready to receive visitors

   666   assert(!is_zombie(),

   667          "should not call follow on zombie nmethod");

   668 

   669   // If the method is not entrant then a JMP is plastered over the

   670   // first few bytes.  If an oop in the old code was there, that oop

   671   // should not get GC'd.  Skip the first few bytes of oops on

   672   // not-entrant methods.

   673   address low_boundary = verified_entry_point();

   674   if (is_not_entrant()) {

   675     low_boundary += NativeJump::instruction_size;

   676     // %%% Note:  On SPARC we patch only a 4-byte trap, not a full NativeJump.

   677     // (See comment above.)

   678   }

   679 

   680   RelocIterator iter(this, low_boundary);

   681   while(iter.next()) {

   682 

   683     switch (iter.type()) {

   684 

   685     case relocInfo::virtual_call_type:

   686       clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);

   687       break;

   688 

   689     case relocInfo::opt_virtual_call_type:

   690       clean_if_nmethod_is_unloaded(CompiledIC_at(&iter), is_alive, this);

   691       break;

   692 

   693     case relocInfo::static_call_type:

   694       clean_if_nmethod_is_unloaded(compiledStaticCall_at(iter.reloc()), is_alive, this);

   695       break;

   696 

   697     default:

   698       break;

   699     }

   700   }

   701 }