RFR 8153123 : Streamline StackWalker code

[Mandy Chung]

> On Apr 4, 2016, at 4:45 PM, Brent Christian <brent.christian at oracle.com> wrote:
> 
> Hi,
> 
> I'd like to check in some footprint and code reduction changes to the java.lang.StackWalker implementation.
> 
> Webrev:
> http://cr.openjdk.java.net/~bchristi/8153123/webrev.00/
> Bug:
> https://bugs.openjdk.java.net/browse/JDK-8153123
> 

This looks good to me.

One thing to mention is that this patch is a follow-up work from the investigation on what it takes to enable Throwable to use StackWalker (JDK-8141239). The current built-in VM backtrace is very compact and performant.  We have identified and prototypes the performance improvements if Throwable backtrace is generated using stack walker.  There are some performance gaps that we agree to defer JDK-8141239 to a future release and improve the footprint performance and GC throughput concerns when MemberNames are stored in the throwable backtrace.

Mandy