RFR: 8293329: x86: Improve handling of constants in AES/GHASH stubs [v3]

[Vladimir Ivanov]

> Pre-generating constants saves on startup and static/dynamic footprint a bit, plus simplifies bootstrapping logic. 
> 
> As a downside, constants aren't guaranteed to be always reachable anymore, but since they are used from stubs, finding a scratch register when needed is not a problem.
> 
> Testing: 
> - [x] hs-tier1 - hs-tier4 w/ `-XX:+ForceUnreachable` 
> - [x] x86_32 build

Vladimir Ivanov 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 three additional commits since the last revision:

 - Merge branch 'stub.x86_64.aes' into stub.x86_64.aes.consts
 - Merge branch 'stub.x86_64.aes' into stub.x86_64.aes.consts
 - constants

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10152/files
  - new: https://git.openjdk.org/jdk/pull/10152/files/7c35132b..332040b5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10152&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10152&range=01-02

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/10152.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10152/head:pull/10152

PR: https://git.openjdk.org/jdk/pull/10152