RFR: 8272315: Improve assert_different_registers [v2]

[Kim Barrett]

> Please review this improvement to assert_different_register.
> 
> It reduces ~250 lines of repetitive code to ~10 lines, and improves the
> error message on failure by printing a duplicated registers name.
> 
> Unfortunately, this isn't enough to eliminate AbstractRegister[Impl].
> Although it seems to no longer be needed for the Oracle-supported platforms,
> the linux-arm/ppc64le/s390 platforms all use the value() function provided
> by AbstractRegisterImpl.
> 
> Testing:
> tier1 on Oracle supported platforms.
> built linux-arm/ppc64le/s390.
> 
> Locally changed a call to have a duplicate register and verified the error
> message had a useful register name.

Kim Barrett has updated the pull request incrementally with one additional commit since the last revision:

  nested loop instead of sort

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/5083/files
  - new: https://git.openjdk.java.net/jdk/pull/5083/files/5042f255..839a5bb8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=5083&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=5083&range=00-01

  Stats: 8 lines in 1 file changed: 2 ins; 4 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5083.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5083/head:pull/5083

PR: https://git.openjdk.java.net/jdk/pull/5083