RFR (T): 8213997: Remove G1HRRSUseSparseTable flag

[Thomas Schatzl]

Hi all,

  can I have reviews to remove the G1HRRSUseSparseTable develop flag?

It has never been used to my recollection, and if so only for doing
performance comparisons.

However in that case you need a modified build anyway as it is a
develop flag, i.e. you already need to modify the code.

Even if you disable Sparse PRTs you still pay some memory costs, so it
does not allow easy memory comparisons anyway.

>From performance/memory consumption POV sparse PRTs are always a win,
in some cases we even recommend to let G1 store more remembered set
entries in sparse PRTs to save memory (without otherwise adverse
effects).

CR:
https://bugs.openjdk.java.net/browse/JDK-8213997
Webrev:
http://cr.openjdk.java.net/~tschatzl/8213997/webrev/
Testing:
local compilation

I consider this change trivial as it consists of code deletion and some
reformatting only.

Thanks,
  Thomas