RFR: 8143900: OptimizeStringConcat has an opaque dependency on Integer.sizeTable field [v2]

[Yi Yang]

> Hi, can I have a review for this patch? I noticed a strange field Integer.sizeTable which is used by PhaseStringOpts, after digging into the history, I think it could be replaced by an in-place array allocation and initialization. Before it, we are fetching from Integer.sizeTable and get num of digit in integer by iterating size table, now we fetch from in-place sizeTable and get size from that. The changed IR looks like this:
> 
> ![image](https://user-images.githubusercontent.com/5010047/220239446-7b8b8381-b300-4f2c-a24a-aa19ec9e2f88.png)
> 
> Thanks.

Yi Yang has updated the pull request incrementally with three additional commits since the last revision:

 - whitespace
 - mirror or Integer.stringSize
 - mirror or Integer.stringSize

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/12680/files
  - new: https://git.openjdk.org/jdk/pull/12680/files/f1794873..816f05a1

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12680&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12680&range=00-01

  Stats: 193 lines in 1 file changed: 67 ins; 114 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/12680.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12680/head:pull/12680

PR: https://git.openjdk.org/jdk/pull/12680