RFR: 8296163: [aarch64] Cleanup Pre/Post addressing mode classes [v2]

[Kim Barrett]

> Please review this cleanup of the aarch64 Pre, Post, and PrePost addressing
> mode helper classes.
> 
> The special functions for the PrePost class are changed from public to
> protected, to ensure no slicing is possible.
> 
> In the Post class constructors, initialization of the members declared
> directly in that class is now performed in the ctor-initializer rather than by
> assignments in the body.
> 
> The member reader functions in PrePost and Post are now const.

Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into pre/post-cleanup
 - cleanup Pre/Post/PrePost

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10929/files
  - new: https://git.openjdk.org/jdk/pull/10929/files/867ad2aa..1306b2ca

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10929&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10929&range=00-01

  Stats: 42347 lines in 285 files changed: 10139 ins; 30874 del; 1334 mod
  Patch: https://git.openjdk.org/jdk/pull/10929.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10929/head:pull/10929

PR: https://git.openjdk.org/jdk/pull/10929