RFR: 8295414: [Aarch64] C2: assert(false) failed: bad AD file [v2]

[Dean Long]

> The "bad AD file" error is because PartialSubtypeCheck produces an iRegP_R5 result, which cannot be matched as an input where iRegP is expected.
> Update the test to reproduce the crash and updated iRegP rule to match iRegP_R5.
> The fact that this went so long without being noticed makes me wonder how much test coverage PartialSubtypeCheck has received on aarch64.

Dean Long has updated the pull request incrementally with one additional commit since the last revision:

  allow test to run with release builds

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/10749/files
  - new: https://git.openjdk.org/jdk/pull/10749/files/87445222..e472a20e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=10749&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=10749&range=00-01

  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/10749.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10749/head:pull/10749

PR: https://git.openjdk.org/jdk/pull/10749