RFR: 8035284: (xs) Remove redundant null initialization

[Mike Duigou]

Apparently javac did at elide the "extraneous" null initialization at one point and it was deemed to have been contrary to point #4 of the procedure in JLS 12.5 (http://docs.oracle.com/javase/specs/jls/se7/html/jls-12.html#jls-12.5-220-D)

Mike


On Apr 11 2014, at 12:57 , Martin Buchholz <martinrb at google.com> wrote:

> It's surprising that javac does not eliminate the redundant initializations to null.  Initializing to null has documentation value (suggesting that the constructor will not assign a value; null is a "valid" value).  How about fixing javac instead?
> 
> 
> On Fri, Apr 11, 2014 at 12:22 PM, Mike Duigou <mike.duigou at oracle.com> wrote:
> Hello all;
> 
> This is a simple cleanup changeset that removes redundant initialization of fields to null from a number of collection classes. These field initializations may seem cheap but they do have a cost:
> 
> - For volatile fields there is a measurable cost on some benchmarks for these extra initializations.
> 
> - Larger byte code in <init> methods.
> 
> - For transient fields the initialization is misleading since it does not occur on deserialization.
> 
> https://bugs.openjdk.java.net/browse/JDK-8035284
> http://cr.openjdk.java.net/~mduigou/JDK-8035284/0/webrev/
> 
> Redundant null initializations in other components/packages will be handled in separate issues.
> 
> Mike
>