RFR: 8251322: Improve BitMap::iterate

[Kim Barrett]

> On Aug 10, 2020, at 3:41 AM, Thomas Schatzl <thomas.schatzl at oracle.com> wrote:
> 
> Hi,
> 
> On 09.08.20 09:44, Kim Barrett wrote:
>> Please review this improvement to BitMap::iterate.  The code is both
>> simplified and made more performant by using get_next_one_bit to scan
>> the bitmap.  Making it inline may allow the compiler to devirtualize
>> and possibly inline the closure invocation.  These changes result in
>> some configurations executing ~1M fewer instructions during startup.
>> CR:
>> https://bugs.openjdk.java.net/browse/JDK-8251322
>> Webrev:
>> https://cr.openjdk.java.net/~kbarrett/8251322/open.00/
>> Testing:
>> mach5 tier1-3.
>> Used Linux-x64 perf on java -version to examine startup impact.
> 
> lgtm.
> 
> Thanks,
>  Thomas

Thanks.