RFR: 8278784: C2: Refactor PhaseIdealLoop::remix_address_expressions() so it operates on longs [v2]

[Roland Westrelin]

> The logic in PhaseIdealLoop::remix_address_expressions() that's
> specific to int nodes apply equally to long nodes. This change
> refactors that code so it applies to both integer types. This improves
> performance on some of panama's micro-benchmarks.

Roland Westrelin 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 four additional commits since the last revision:

 - Christian's review
 - Merge branch 'master' into JDK-8278784
 - test
 - remix address

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6892/files
  - new: https://git.openjdk.java.net/jdk/pull/6892/files/c09069ea..06f67b56

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6892&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6892&range=00-01

  Stats: 6835 lines in 276 files changed: 5029 ins; 952 del; 854 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6892.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6892/head:pull/6892

PR: https://git.openjdk.java.net/jdk/pull/6892