8289126: Cleanup unnecessary null comparison before instanceof check in jdk.hotspot.agent

Reviewed-by: ayang, cjplummer

Author: Andrey Turbanov

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/CommandProcessor.java

@@ -581,8 +581,8 @@ public void doit(Tokens t) {
                     // dump replay data
 
                     CodeBlob cb = VM.getVM().getCodeCache().findBlob(a);
-                    if (cb != null && (cb instanceof NMethod)) {
-                        ((NMethod)cb).dumpReplayData(out);
+                    if (cb instanceof NMethod nMethod) {
+                        nMethod.dumpReplayData(out);
                         return;
                     }
                     // assume it is Metadata

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/bsd/BsdThread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2022, 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
@@ -49,11 +49,11 @@ class BsdThread implements ThreadProxy {
     }
 
     public boolean equals(Object obj) {
-        if ((obj == null) || !(obj instanceof BsdThread)) {
+        if (!(obj instanceof BsdThread other)) {
             return false;
         }
 
-        return (((BsdThread) obj).unique_thread_id == unique_thread_id);
+        return (other.unique_thread_id == unique_thread_id);
     }
 
     public int hashCode() {

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/cdbg/LoadObjectComparator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2022, 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
@@ -38,9 +38,6 @@ public int compare(LoadObject lo1, LoadObject lo2) {
    }
 
    public boolean equals(Object o) {
-      if (o == null || !(o instanceof LoadObjectComparator)) {
-         return false;
-      }
-      return true;
+      return o instanceof LoadObjectComparator;
    }
 }

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/linux/LinuxThread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2022, 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
@@ -55,11 +55,11 @@ class LinuxThread implements ThreadProxy {
     }
 
     public boolean equals(Object obj) {
-        if ((obj == null) || !(obj instanceof LinuxThread)) {
+        if (!(obj instanceof LinuxThread other)) {
             return false;
         }
 
-        return (((LinuxThread) obj).lwp_id == lwp_id);
+        return (other.lwp_id == lwp_id);
     }
 
     public int hashCode() {

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/posix/DSO.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2022, 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
@@ -25,7 +25,6 @@
 
 import sun.jvm.hotspot.debugger.*;
 import sun.jvm.hotspot.debugger.cdbg.*;
-import sun.jvm.hotspot.utilities.memo.*;
 
 /** Provides a simple wrapper around the ELF library which handles
     relocation. */
@@ -69,10 +68,9 @@ public LineNumberInfo lineNumberForPC(Address pc) throws DebuggerException {
     }
 
     public boolean equals(Object o) {
-        if (o == null || !(o instanceof DSO)) {
+        if (!(o instanceof DSO other)) {
            return false;
         }
-        DSO other = (DSO)o;
         return getBase().equals(other.getBase());
     }
 

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/proc/aarch64/ProcAARCH64Thread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2015, Red Hat Inc.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
@@ -74,11 +74,11 @@ public String toString() {
     }
 
     public boolean equals(Object obj) {
-        if ((obj == null) || !(obj instanceof ProcAARCH64Thread)) {
+        if (!(obj instanceof ProcAARCH64Thread other)) {
             return false;
         }
 
-        return (((ProcAARCH64Thread) obj).id == id);
+        return (other.id == id);
     }
 
     public int hashCode() {

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/proc/amd64/ProcAMD64Thread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2022, 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
@@ -73,11 +73,11 @@ public String toString() {
     }
 
     public boolean equals(Object obj) {
-        if ((obj == null) || !(obj instanceof ProcAMD64Thread)) {
+        if (!(obj instanceof ProcAMD64Thread other)) {
             return false;
         }
 
-        return (((ProcAMD64Thread) obj).id == id);
+        return (other.id == id);
     }
 
     public int hashCode() {

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/proc/ppc64/ProcPPC64Thread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2022, 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
@@ -73,11 +73,11 @@ public String toString() {
   }
 
   public boolean equals(Object obj) {
-    if ((obj == null) || !(obj instanceof ProcPPC64Thread)) {
+    if (!(obj instanceof ProcPPC64Thread other)) {
       return false;
     }
 
-    return (((ProcPPC64Thread) obj).id == id);
+    return (other.id == id);
   }
 
   public int hashCode() {

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/proc/riscv64/ProcRISCV64Thread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2004, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2015, Red Hat Inc.
  * Copyright (c) 2021, Huawei Technologies Co., Ltd. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
@@ -75,11 +75,11 @@ public String toString() {
     }
 
     public boolean equals(Object obj) {
-        if ((obj == null) || !(obj instanceof ProcRISCV64Thread)) {
+        if (!(obj instanceof ProcRISCV64Thread other)) {
             return false;
         }
 
-        return (((ProcRISCV64Thread) obj).id == id);
+        return (other.id == id);
     }
 
     public int hashCode() {

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/proc/x86/ProcX86Thread.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2003, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2022, 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
@@ -78,11 +78,11 @@ public String toString() {
   }
 
   public boolean equals(Object obj) {
-    if ((obj == null) || !(obj instanceof ProcX86Thread)) {
+    if (!(obj instanceof ProcX86Thread other)) {
       return false;
     }
 
-    return (((ProcX86Thread) obj).id == id);
+    return (other.id == id);
   }
 
   public int hashCode() {