RFR: 8283094: Add Ideal transformation: x + (con - y) -> (x - y) + con [v3]

Wed Mar 23 06:16:29 UTC 2022

On Mon, 21 Mar 2022 22:08:09 GMT, Zhiqiang Zang <duke at openjdk.java.net> wrote:

>> Hello,
>> 
>> `x + (con - y)  -> (x - y) + con` is a widely seen pattern; however it is missing in current implementation, which prevents some obvious constant folding from happening, such as `x + (1 - y) + 2` will be not optimized at all, rather than into `x - y + 3`.
>> 
>> This pull request adds this transformation.
>
> Zhiqiang Zang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   move tests to existing test classes.

test/hotspot/jtreg/compiler/c2/irTests/AddINodeIdealizationTests.java line 47:

> 45:                  "test14", "test15", "test16",
> 46:                  "test17", "test18", "test19",
> 47:                  "testXPlus_PosConMinusY_", "testXPlus_NegConMinusY_",

Please make the name uniform and put them in correct order, thanks.

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PR: https://git.openjdk.java.net/jdk/pull/7795