RFR(T): 8252125: add an "inflating" entry to the "table" of bit patterns in share/oops/markWord.hpp

[Daniel D. Daugherty]

Greetings,

I have a trivial fix to add more clarification to markWord bit patterns.

Here's the bug report:

     JDK-8252125 add an "inflating" entry to the "table" of bit patterns in
                 share/oops/markWord.hpp
     https://bugs.openjdk.java.net/browse/JDK-8252125

And here's the context diff for the trivial change itself:

$ hg diff -r qparent
diff -r 8f73aeccb27c src/hotspot/share/oops/markWord.hpp
--- a/src/hotspot/share/oops/markWord.hpp    Thu Aug 20 11:12:00 2020 -0700
+++ b/src/hotspot/share/oops/markWord.hpp    Thu Aug 20 16:39:11 2020 -0400
@@ -84,12 +84,13 @@
  //    [header      | 0 | 01]  unlocked           regular object header
  //    [ptr             | 10]  monitor            inflated lock (header 
is wapped out)
  //    [ptr             | 11]  marked             used to mark an object
+//    [0 ............ 0| 00]  inflating          inflation in progress
  //
  //    We assume that stack/thread pointers have the lowest two bits 
cleared.
  //
-//  - INFLATING() is a distinguished markword value that is used when
-//    inflating an existing stack-lock into an ObjectMonitor. See below
-//    for is_being_inflated() and INFLATING().
+//  - INFLATING() is a distinguished markword value of all zeros that is
+//    used when inflating an existing stack-lock into an ObjectMonitor.
+//    See below for is_being_inflated() and INFLATING().

  class BasicLock;
  class ObjectMonitor;

Thanks, in advance, for any comments, questions or suggestions.

Dan