8245216: [lworld] The JVM should inject the IdentityObject interface to types which need it

src/hotspot/share/classfile/verificationType.cpp

@@ -60,7 +60,8 @@ bool VerificationType::resolve_and_check_assignability(InstanceKlass* klass, Sym
       from_name != vmSymbols::java_lang_Object())) {
     // If we are not trying to access a protected field or method in
     // java.lang.Object then, for arrays, we only allow assignability
-    // to interfaces java.lang.Cloneable and java.io.Serializable.
+    // to interfaces java.lang.Cloneable, java.io.Serializable,
+    // and java.lang.IdentityObject.
     // Otherwise, we treat interfaces as java.lang.Object.
     return !from_is_array ||
       this_class == SystemDictionary::Cloneable_klass() ||

test/hotspot/jtreg/serviceability/dcmd/vm/ClassHierarchyTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2015, 2020, 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
@@ -79,10 +79,12 @@ public class ClassHierarchyTest {
         Pattern.compile("java.lang.Object/null"),
         Pattern.compile("\\|--DcmdBaseClass/0x(\\p{XDigit}*)"),
         Pattern.compile("\\|  implements Intf2/0x(\\p{XDigit}*) \\(declared intf\\)"),
+        Pattern.compile("\\|  implements java.lang.IdentityObject/null \\(declared intf\\)"),
         Pattern.compile("\\|  implements Intf1/0x(\\p{XDigit}*) \\(inherited intf\\)"),
         Pattern.compile("\\|  \\|--DcmdTestClass/0x(\\p{XDigit}*)"),
         Pattern.compile("\\|  \\|  implements Intf1/0x(\\p{XDigit}*) \\(inherited intf\\)"),
-        Pattern.compile("\\|  \\|  implements Intf2/0x(\\p{XDigit}*) \\(inherited intf\\)")
+        Pattern.compile("\\|  \\|  implements Intf2/0x(\\p{XDigit}*) \\(inherited intf\\)"),
+        Pattern.compile("\\|  \\|  implements java.lang.IdentityObject/null \\(inherited intf\\)")
     };
 
     public void run(CommandExecutor executor) throws ClassNotFoundException {
@@ -140,7 +142,7 @@ public void run(CommandExecutor executor) throws ClassNotFoundException {
                 Assert.fail("Failed to match line #" + i + ": " + line);
             }
             // "implements" lines should not be in this output.
-            if (i == 2 || i == 4) i += 2;
+            if (i == 2 || i == 6) i += 3;
         }
         if (lines.hasNext()) {
             String line = lines.next();
@@ -164,7 +166,7 @@ public void run(CommandExecutor executor) throws ClassNotFoundException {
                 // subsequent lines.
                 classLoaderAddr = m.group(1);
                 System.out.println(classLoaderAddr);
-            } else if (i > 2) {
+            } else if (i > 2 && i != 4 && i != 9) {
                 if (!classLoaderAddr.equals(m.group(1))) {
                     Assert.fail("Classloader address didn't match on line #"
                                         + i + ": " + line);

test/hotspot/jtreg/vmTestbase/nsk/jdwp/ReferenceType/Interfaces/interfaces001.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2020, 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
@@ -50,6 +50,7 @@ public class interfaces001 {
                 };
     static final int DECLARED_INTERFACES = class_interfaces.length;
     static final long interfaceIDs[] = new long[DECLARED_INTERFACES];
+    static long identityObjectID;
 
     public static void main (String argv[]) {
         System.exit(run(argv,System.out) + JCK_STATUS_BASE);
@@ -98,6 +99,7 @@ public int runIt(String argv[], PrintStream out) {
                         log.display("Getting ReferenceTypeID for interface signature: " + class_interfaces[i][1]);
                         interfaceIDs[i] = debugee.getReferenceTypeID(class_interfaces[i][1]);
                     }
+                    identityObjectID = debugee.getReferenceTypeID("Ljava/lang/IdentityObject;");
 
                     // begin test of JDWP command
 
@@ -124,7 +126,8 @@ public int runIt(String argv[], PrintStream out) {
                     int interfaces = reply.getInt();
                     log.display("  interfaces: " + interfaces);
 
-                    if (interfaces != DECLARED_INTERFACES) {
+                    // Adding one to the number of interfaces because of the injection of IdentityObject by the VM
+                    if (interfaces != DECLARED_INTERFACES + 1) {
                         log.complain("Unexpected number of declared interfaces in the reply packet:" + interfaces
                                     + " (expected: " + DECLARED_INTERFACES + ")");
                         success = false;
@@ -137,12 +140,19 @@ public int runIt(String argv[], PrintStream out) {
                         long interfaceID = reply.getReferenceTypeID();
                         log.display("    interfaceID: " + interfaceID);
 
-                        if (interfaceID != interfaceIDs[i]) {
-                            log.complain("Unexpected interface ID for interface #" + i + " in the reply packet: " + interfaceID
-                                        + " (expected: " + interfaceIDs[i] + ")");
-                            success = false;
+                        if (i < DECLARED_INTERFACES) {
+                            if (interfaceID != interfaceIDs[i]) {
+                                log.complain("Unexpected interface ID for interface #" + i + " in the reply packet: " + interfaceID
+                                             + " (expected: " + interfaceIDs[i] + ")");
+                                success = false;
+                            }
+                        } else {
+                            if (interfaceID != identityObjectID) {
+                                log.complain("Unexpected interface ID for interface #" + i + " in the reply packet: " + interfaceID
+                                             + " (expected identityObjectID: " + identityObjectID + ")");
+                                success = false;
+                            }
                         }
-
                     }
 
                     if (! reply.isParsed()) {