src/hotspot/share/code/codeCache.cpp

ZGC: 8212989: Allow CompiledMethod ExceptionCache have unloaded klasses

*** 144,153 ****
--- 144,154 ----
  address CodeCache::_low_bound = 0;
  address CodeCache::_high_bound = 0;
  int CodeCache::_number_of_nmethods_with_dependencies = 0;
  bool CodeCache::_needs_cache_clean = false;
  nmethod* CodeCache::_scavenge_root_nmethods = NULL;
+ ExceptionCache* volatile CodeCache::_exception_cache_purge_list = NULL;
  
  // Initialize arrays of CodeHeap subsets
  GrowableArray<CodeHeap*>* CodeCache::_heaps = new(ResourceObj::C_HEAP, mtCode) GrowableArray<CodeHeap*> (CodeBlobType::All, true);
  GrowableArray<CodeHeap*>* CodeCache::_compiled_heaps = new(ResourceObj::C_HEAP, mtCode) GrowableArray<CodeHeap*> (CodeBlobType::All, true);
  GrowableArray<CodeHeap*>* CodeCache::_nmethod_heaps = new(ResourceObj::C_HEAP, mtCode) GrowableArray<CodeHeap*> (CodeBlobType::All, true);
***************
*** 900,909 ****
--- 901,938 ----
    assert(count + InlineCacheBuffer::pending_icholder_count() + CompiledICHolder::live_not_claimed_count() ==
           CompiledICHolder::live_count(), "must agree");
  #endif
  }
  
+ // Defer freeing of concurrently cleaned ExceptionCache entries until
+ // after a global handshake operation.
+ void CodeCache::release_exception_cache(ExceptionCache* entry) {
+   if (SafepointSynchronize::is_at_safepoint()) {
+     delete entry;
+   } else {
+     for (;;) {
+       ExceptionCache* free_list_head = Atomic::load(&_exception_cache_purge_list);
+       entry->set_purge_list_next(free_list_head);
+       if (Atomic::cmpxchg(entry, &_exception_cache_purge_list, free_list_head) == free_list_head) {
+         break;
+       }
+     }
+   }
+ }
+ 
+ // Delete exception caches that have been concurrently unlinked,
+ // followed by a global handshake operation.
+ void CodeCache::purge_exception_caches() {
+   ExceptionCache* curr = _exception_cache_purge_list;
+   while (curr != NULL) {
+     ExceptionCache* next = curr->purge_list_next();
+     delete curr;
+     curr = next;
+   }
+   _exception_cache_purge_list = NULL;
+ }
+ 
  void CodeCache::gc_prologue() { }
  
  void CodeCache::gc_epilogue() {
    prune_scavenge_root_nmethods();
  }