RFR: 8185925 & 8153682 (footprint reduction of java.lang.StackFrameInfo)

[mandy chung]

On 11/6/17 4:23 PM, Brent Christian wrote:
> Please review my code change for this.  The webrev is here:
> http://cr.openjdk.java.net/~bchristi/8185925/webrev.03/
>

It's a good footprint improvement.  Thanks for doing this.

StackFrameInfo.java

   38     // Footprint improvement: MemberName::clazz can replace
   39     // StackFrameInfo::declaringClass.


The above comment can be removed.

41 private final boolean retainClassRef;

JVMS [1] has a note about Hotspot implementation of boolean array that 
is encoded as a byte array. That explains JOL output that this boolean 
field is 8-bit in our implementation.  This field could be changed to a 
byte to hold additional flags, if any in the future.  It may be good to 
change this to a byte making the field size explicit.

Otherwise looks good.

Mandy
[1] 
https://docs.oracle.com/javase/specs/jvms/se9/html/jvms-2.html#jvms-2.3.4
> An automated test run is in progress.
>
> Thanks!
> -Brent
>
> -- 
> 1. https://bugs.openjdk.java.net/browse/JDK-8153682
> 2. https://bugs.openjdk.java.net/browse/JDK-8185925
> 3. http://openjdk.java.net/projects/code-tools/jol/
> 4. 
> http://cr.openjdk.java.net/~bchristi/8185925/StackFrameInfo.jol.baseline.txt
> 5. 
> http://cr.openjdk.java.net/~bchristi/8185925/StackFrameInfo.jol.rmDeclClass.txt