RFR: 8281453: New optimization: convert `~x` into `-1-x` when `~x` is used in an arithmetic expression [v15]

[Zhiqiang Zang]

> Similar to `(~x)+c` -> `(c-1)-x` and `~(x+c)` -> `(-c-1)-x` in #6858, we can also introduce similar optimizations for subtraction, `c-(~x)` -> `x+(c+1)` and `~(c-x)` -> `x+(-c-1)`.
> 
> To generalize, I convert `~x` into `-1-x` when `~x` is used only in arithmetic expression. For example, `c-(~x)` will be converted into `c-(-1-x)` which will match other pattern and will be transformed again in next iteration and finally become `x+(c+1)`.
> 
> Also the conversion from `~x` into `-1-x` happens when `x` is an arithmetic expression itself. For example, `~(x+c)` will be transformed into `-1-(x+c)` and eventually `(-c-1)-x`.
> 
> The results of the microbenchmark are as follows:
> 
> Baseline:
> Benchmark                         Mode  Cnt  Score   Error  Units
> NotOpTransformation.baselineInt   avgt   60  0.448 ± 0.002  ns/op
> NotOpTransformation.baselineLong  avgt   60  0.448 ± 0.002  ns/op
> NotOpTransformation.testInt1      avgt   60  0.615 ± 0.003  ns/op
> NotOpTransformation.testInt2      avgt   60  0.838 ± 0.004  ns/op
> NotOpTransformation.testLong1     avgt   60  0.671 ± 0.003  ns/op
> NotOpTransformation.testLong2     avgt   60  0.670 ± 0.003  ns/op
> 
> Patch:
> Benchmark                         Mode  Cnt  Score   Error  Units
> NotOpTransformation.baselineInt   avgt   60  0.451 ± 0.003  ns/op
> NotOpTransformation.baselineLong  avgt   60  0.447 ± 0.002  ns/op
> NotOpTransformation.testInt1      avgt   60  0.334 ± 0.002  ns/op
> NotOpTransformation.testInt2      avgt   60  0.334 ± 0.002  ns/op
> NotOpTransformation.testLong1     avgt   60  0.334 ± 0.002  ns/op
> NotOpTransformation.testLong2     avgt   60  0.335 ± 0.002  ns/op

Zhiqiang Zang has updated the pull request incrementally with one additional commit since the last revision:

  remove one use check for long as well.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/7376/files
  - new: https://git.openjdk.org/jdk/pull/7376/files/d7183474..91407ddf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=7376&range=14
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=7376&range=13-14

  Stats: 12 lines in 2 files changed: 9 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/7376.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/7376/head:pull/7376

PR: https://git.openjdk.org/jdk/pull/7376