src/hotspot/share/prims/jvmtiTagMapTable.cpp

@@ -1,7 +1,7 @@
  /*
-  * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved.
+  * Copyright (c) 2020, 2024, 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
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.

@@ -62,10 +62,27 @@
  oop JvmtiTagMapKey::object_no_keepalive() const {
    assert(_obj == nullptr, "Must have a handle and not object");
    return _wh.peek();
  }
  
+ unsigned JvmtiTagMapKey::get_hash(const JvmtiTagMapKey& entry) {
+   oop obj = entry._obj;
+   assert(obj != nullptr, "must lookup obj to hash");
+   if (obj->is_inline_type()) {
+     // For inline types, use the klass as a hash code and let the equals match the obj.
+     // It might have a long bucket but TBD to improve this if a customer situation arises.
+     return (unsigned)((int64_t)obj->klass() >> 3);
+   } else {
+     return (unsigned)obj->identity_hash();
+   }
+ }
+ 
+ // Inline types don't use hash for this table.
+ static inline bool fast_no_hash_check(oop obj) {
+   return (obj->fast_no_hash_check() && !obj->is_inline_type());
+ }
+ 
  static const int INITIAL_TABLE_SIZE = 1007;
  static const int MAX_TABLE_SIZE     = 0x3fffffff;
  
  JvmtiTagMapTable::JvmtiTagMapTable() : _table(INITIAL_TABLE_SIZE, MAX_TABLE_SIZE) {}
  

@@ -92,12 +109,12 @@
  jlong JvmtiTagMapTable::find(oop obj) {
    if (is_empty()) {
      return 0;
    }
  
-   if (obj->fast_no_hash_check()) {
-     // Objects in the table all have a hashcode.
+   if (fast_no_hash_check(obj)) {
+     // Objects in the table all have a hashcode, unless inlined types.
      return 0;
    }
  
    JvmtiTagMapKey jtme(obj);
    jlong* found = _table.get(jtme);

@@ -105,11 +122,11 @@
  }
  
  void JvmtiTagMapTable::add(oop obj, jlong tag) {
    JvmtiTagMapKey new_entry(obj);
    bool is_added;
-   if (obj->fast_no_hash_check()) {
+   if (fast_no_hash_check(obj)) {
      // Can't be in the table so add it fast.
      is_added = _table.put_when_absent(new_entry, tag);
    } else {
      jlong* value = _table.put_if_absent(new_entry, tag, &is_added);
      *value = tag; // assign the new tag