RFR JDK-8193325: StackFrameInfo::getByteCodeIndex returns wrong value if bci > 32767

[Mandy Chung]

On 8/12/19 11:33 AM, Aleksey Shipilev wrote:
>> Alternatively, we can make bci an int (as Alekey suggests) that does not increase the object size:
>>
>>     http://cr.openjdk.java.net/~mchung/jdk14/8193325/webrev.02/
> @Stable seems meaningless here, for the reasons Daniel points out. I believe "final int bci" is just as good and clean.

I am happy to keep it final field and the comment already indicates that 
the field is set by the VM.  It's initialized to -1 in case any accident 
change that VM didn't set this field.


diff --git a/src/java.base/share/classes/java/lang/StackFrameInfo.java 
b/src/java.base/share/classes/java/lang/StackFrameInfo.java
--- a/src/java.base/share/classes/java/lang/StackFrameInfo.java
+++ b/src/java.base/share/classes/java/lang/StackFrameInfo.java
@@ -1,5 +1,5 @@
  /*
- * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights 
reserved.
+ * Copyright (c) 2015, 2019, 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
@@ -26,28 +26,31 @@

  import jdk.internal.access.JavaLangInvokeAccess;
  import jdk.internal.access.SharedSecrets;
+import jdk.internal.vm.annotation.Stable;

  import java.lang.StackWalker.StackFrame;
  import java.lang.invoke.MethodType;

  class StackFrameInfo implements StackFrame {
-    private final byte RETAIN_CLASS_REF = 0x01;
+    private final static byte RETAIN_CLASS_REF = 0x01;

      private final static JavaLangInvokeAccess JLIA =
          SharedSecrets.getJavaLangInvokeAccess();

      private final byte flags;
-    private final Object memberName;
-    private final short bci;
+    private final Object memberName;    // MemberName initialized by VM
+    private final int bci = -1;         // BCI set by VM
      private volatile StackTraceElement ste;

      /*
-     * Create StackFrameInfo for StackFrameTraverser and 
LiveStackFrameTraverser
-     * to use
+     * Construct an empty StackFrameInfo object that will be filled by 
the VM
+     * during stack walking.
+     *
+     * @see StackStreamFactory.AbstractStackWalker#callStackWalk
+     * @see StackStreamFactory.AbstractStackWalker#fetchStackFrames
       */
      StackFrameInfo(StackWalker walker) {
          this.flags = walker.retainClassRef ? RETAIN_CLASS_REF : 0;
-        this.bci = -1;
          this.memberName = JLIA.newMemberName();
      }