8199406: Performance drop with Java JDK 1.8.0_162-b32

Summary: Improve the nmethod unloading times by optimizing the search for an itable stub in VtableStubs array
Reviewed-by: kvn, coleenp, tschatzl

src/share/vm/code/codeBlob.cpp

 /*
- * Copyright (c) 1998, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -289,6 +289,28 @@ AdapterBlob* AdapterBlob::create(CodeBuffer* cb) {
   return blob;
 }
 
+VtableBlob::VtableBlob(const char* name, int size) :
+  BufferBlob(name, size) {
+}
+
+VtableBlob* VtableBlob::create(const char* name, int buffer_size) {
+  ThreadInVMfromUnknown __tiv;  // get to VM state in case we block on CodeCache_lock
+
+  VtableBlob* blob = NULL;
+  unsigned int size = sizeof(VtableBlob);
+  // align the size to CodeEntryAlignment
+  size = align_code_offset(size);
+  size += round_to(buffer_size, oopSize);
+  assert(name != NULL, "must provide a name");
+  {
+    MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
+    blob = new (size) VtableBlob(name, size);
+  }
+  // Track memory usage statistic after releasing CodeCache_lock
+  MemoryService::track_code_cache_memory_usage();
+
+  return blob;
+}
 
 //----------------------------------------------------------------------------------------------------
 // Implementation of MethodHandlesAdapterBlob

src/share/vm/code/codeBlob.hpp

 /*
- * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -101,6 +101,7 @@ class CodeBlob VALUE_OBJ_CLASS_SPEC {
   virtual bool is_exception_stub() const         { return false; }
   virtual bool is_safepoint_stub() const              { return false; }
   virtual bool is_adapter_blob() const                { return false; }
+  virtual bool is_vtable_blob() const                 { return false; }
   virtual bool is_method_handles_adapter_blob() const { return false; }
 
   virtual bool is_compiled_by_c2() const         { return false; }
@@ -202,6 +203,7 @@ class CodeBlob VALUE_OBJ_CLASS_SPEC {
 class BufferBlob: public CodeBlob {
   friend class VMStructs;
   friend class AdapterBlob;
+  friend class VtableBlob;
   friend class MethodHandlesAdapterBlob;
 
  private:
@@ -246,6 +248,18 @@ public:
   virtual bool is_adapter_blob() const { return true; }
 };
 
+//---------------------------------------------------------------------------------------------------
+class VtableBlob: public BufferBlob {
+private:
+  VtableBlob(const char*, int);
+
+public:
+  // Creation
+  static VtableBlob* create(const char* name, int buffer_size);
+
+  // Typing
+  virtual bool is_vtable_blob() const { return true; }
+};
 
 //----------------------------------------------------------------------------------------------------
 // MethodHandlesAdapterBlob: used to hold MethodHandles adapters

src/share/vm/code/compiledIC.cpp

 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -232,7 +232,7 @@ bool CompiledIC::set_to_megamorphic(CallInfo* call_info, Bytecodes::Code bytecod
     assert(k->verify_itable_index(itable_index), "sanity check");
 #endif //ASSERT
     CompiledICHolder* holder = new CompiledICHolder(call_info->resolved_method()->method_holder(),
-                                                    call_info->resolved_klass()());
+                                                    call_info->resolved_klass()(), false);
     holder->claim();
     InlineCacheBuffer::create_transition_stub(this, holder, entry);
   } else {
@@ -270,7 +270,7 @@ bool CompiledIC::is_megamorphic() const {
   assert(!is_optimized(), "an optimized call cannot be megamorphic");
 
   // Cannot rely on cached_value. It is either an interface or a method.
-  return VtableStubs::is_entry_point(ic_destination());
+  return VtableStubs::entry_point(ic_destination()) != NULL;
 }
 
 bool CompiledIC::is_call_to_compiled() const {
@@ -534,9 +534,11 @@ bool CompiledIC::is_icholder_entry(address entry) {
     return true;
   }
   // itable stubs also use CompiledICHolder
-  if (VtableStubs::is_entry_point(entry) && VtableStubs::stub_containing(entry)->is_itable_stub()) {
-    return true;
+  if (cb != NULL && cb->is_vtable_blob()) {
+    VtableStub* s = VtableStubs::entry_point(entry);
+    return (s != NULL) && s->is_itable_stub();
   }
+
   return false;
 }
 

src/share/vm/code/vtableStubs.cpp

 /*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -60,7 +60,7 @@ void* VtableStub::operator new(size_t size, int code_size) throw() {
 
    // There is a dependency on the name of the blob in src/share/vm/prims/jvmtiCodeBlobEvents.cpp
    // If changing the name, update the other file accordingly.
-    BufferBlob* blob = BufferBlob::create("vtable chunks", bytes);
+    VtableBlob* blob = VtableBlob::create("vtable chunks", bytes);
     if (blob == NULL) {
       return NULL;
     }
@@ -167,17 +167,18 @@ void VtableStubs::enter(bool is_vtable_stub, int vtable_index, VtableStub* s) {
   _number_of_vtable_stubs++;
 }
 
-
-bool VtableStubs::is_entry_point(address pc) {
+VtableStub* VtableStubs::entry_point(address pc) {
   MutexLocker ml(VtableStubs_lock);
   VtableStub* stub = (VtableStub*)(pc - VtableStub::entry_offset());
   uint hash = VtableStubs::hash(stub->is_vtable_stub(), stub->index());
   VtableStub* s;
   for (s = _table[hash]; s != NULL && s != stub; s = s->next()) {}
-  return s == stub;
+  if (s == stub) {
+    return s;
+  }
+  return NULL;
 }
 
-
 bool VtableStubs::contains(address pc) {
   // simple solution for now - we may want to use
   // a faster way if this function is called often

src/share/vm/code/vtableStubs.hpp

 /*
- * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -126,7 +126,7 @@ class VtableStubs : AllStatic {
  public:
   static address     find_vtable_stub(int vtable_index) { return find_stub(true,  vtable_index); }
   static address     find_itable_stub(int itable_index) { return find_stub(false, itable_index); }
-  static bool        is_entry_point(address pc);                     // is pc a vtable stub entry point?
+  static VtableStub* entry_point(address pc);                        // vtable stub entry point for a pc
   static bool        contains(address pc);                           // is pc within any stub?
   static VtableStub* stub_containing(address pc);                    // stub containing pc or NULL
   static int         number_of_vtable_stubs() { return _number_of_vtable_stubs; }

src/share/vm/oops/compiledICHolder.cpp

 /*
- * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,30 +24,12 @@
 
 #include "precompiled.hpp"
 #include "oops/compiledICHolder.hpp"
-#include "oops/klass.hpp"
-#include "oops/method.hpp"
 #include "oops/oop.inline2.hpp"
 
 volatile int CompiledICHolder::_live_count;
 volatile int CompiledICHolder::_live_not_claimed_count;
 
 
-bool CompiledICHolder::is_loader_alive(BoolObjectClosure* is_alive) {
-  if (_holder_metadata->is_method()) {
-    if (!((Method*)_holder_metadata)->method_holder()->is_loader_alive(is_alive)) {
-      return false;
-    }
-  } else if (_holder_metadata->is_klass()) {
-    if (!((Klass*)_holder_metadata)->is_loader_alive(is_alive)) {
-      return false;
-    }
-  }
-  if (!_holder_klass->is_loader_alive(is_alive)) {
-    return false;
-  }
-  return true;
-}
-
 // Printing
 
 void CompiledICHolder::print_on(outputStream* st) const {

src/share/vm/oops/compiledICHolder.hpp

 /*
- * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,8 @@
 #define SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP
 
 #include "oops/oop.hpp"
+#include "oops/klass.hpp"
+#include "oops/method.hpp"
 
 // A CompiledICHolder* is a helper object for the inline cache implementation.
 // It holds:
@@ -48,11 +50,12 @@ class CompiledICHolder : public CHeapObj<mtCompiler> {
   Metadata* _holder_metadata;
   Klass*    _holder_klass;    // to avoid name conflict with oopDesc::_klass
   CompiledICHolder* _next;
+  bool _is_metadata_method;
 
  public:
   // Constructor
-  CompiledICHolder(Metadata* metadata, Klass* klass)
-      : _holder_metadata(metadata), _holder_klass(klass) {
+  CompiledICHolder(Metadata* metadata, Klass* klass, bool is_method = true)
+      : _holder_metadata(metadata), _holder_klass(klass), _is_metadata_method(is_method) {
 #ifdef ASSERT
     Atomic::inc(&_live_count);
     Atomic::inc(&_live_not_claimed_count);
@@ -82,7 +85,16 @@ class CompiledICHolder : public CHeapObj<mtCompiler> {
   CompiledICHolder* next()     { return _next; }
   void set_next(CompiledICHolder* n) { _next = n; }
 
-  bool is_loader_alive(BoolObjectClosure* is_alive);
+  inline bool is_loader_alive(BoolObjectClosure* is_alive) {
+    Klass* k = _is_metadata_method ? ((Method*)_holder_metadata)->method_holder() : (Klass*)_holder_metadata;
+    if (!k->is_loader_alive(is_alive)) {
+      return false;
+    }
+    if (!_holder_klass->is_loader_alive(is_alive)) {
+      return false;
+    }
+    return true;
+  }
 
   // Verify
   void verify_on(outputStream* st);