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

[Vladimir Kozlov]

On Fri, 24 Feb 2023 10:19:49 GMT, Yi Yang <yyang at openjdk.org> wrote:

>> 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

Code looks reasonable and matches `Integer.stringSize()` method. I will test it.

src/hotspot/share/opto/stringopts.cpp line 1163:

> 1161: }
> 1162: 
> 1163: // Mirror of Integer.stringSize, return the count of digits in integer,

`Integer.stringSize() method`

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