RFR: 8278784: C2: Refactor PhaseIdealLoop::remix_address_expressions() so it operates on longs [v4]

[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 incrementally with one additional commit since the last revision:

  review

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6892/files
  - new: https://git.openjdk.java.net/jdk/pull/6892/files/e8e3385b..702e03ad

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6892&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6892&range=02-03

  Stats: 34 lines in 2 files changed: 0 ins; 0 del; 34 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