RFR: 8256438: AArch64: Implement match rules with ROR shift register value [v4]

[Eric Liu]

> This patch transforms '(x >>> rshift) + (x << lshift)' into
> 'RotateRight(x, rshift)' during GVN phase when both the shift exponents
> are constants and their sum equals to the number of bits for the type
> of shift base.
> 
> This patch implements some new match rules for AArch64 instructions
> which can take ROR as the optional shift. Such instructions are 'and',
> 'or', 'eor', 'eon', 'bic' and 'orn'.
> 
>   ror     w11, w2, #5
>   eor     w0, w1, w11
> 
> With this patch, above code could be optimized to below:
> 
>   eor     w0, w1, w2, ror #5
> 
> Finally, the patch refactors TestRotate.java[1][2].
> 
> Tested jtreg TestRotate.java, hotspot::hotspot_all_no_apps,
> jdk::jdk_core, langtools::tier1.
> 
> [1] https://bugs.openjdk.java.net/browse/JDK-8252776
> [2] https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2020-September/039911.html

Eric Liu has updated the pull request incrementally with one additional commit since the last revision:

  Add null check
  
  Change-Id: I18dda4a01154bce72fd4025685fa0721263092ce

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/1858/files
  - new: https://git.openjdk.java.net/jdk/pull/1858/files/492f4ca4..93577236

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=1858&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=1858&range=02-03

  Stats: 22 lines in 1 file changed: 4 ins; 0 del; 18 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1858.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1858/head:pull/1858

PR: https://git.openjdk.java.net/jdk/pull/1858