RFR: 8280872: Reorder code cache segments to improve code density [v4]

[Boris Ulasevich]

> Currently the codecache segment order is [non-nmethod, non-profiled, profiled]. With this change we move the non-nmethod segment between two code segments. It changes nothing for any platform besides AARCH.
> 
> In AARCH the offset limit for a branch instruction is 128MB. The bigger jumps are encoded with three instructions. Most of far branches are jumps into the non-nmethod blobs. With the non-nmethod segment in between code segments the jump distance from method to the stub becomes shorter. The result is a 4% reduction in generated code size for the CodeCache range from 128MB to 240MB.
> 
> As a side effect, the performance of some tests is slightly improved:
> ``ArraysFill.testCharFill      10  thrpt   15  170235.720 -> 178477.212  ops/ms``
> 
> Testing: jdk/hotspot jtreg and microbenchmarks on AMD and AARCH

Boris Ulasevich has updated the pull request incrementally with two additional commits since the last revision:

 - moving nops out of far_jump
 - minor renaming

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7517/files
  - new: https://git.openjdk.java.net/jdk/pull/7517/files/5f0fe37c..91e62888

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7517&range=03
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7517&range=02-03

  Stats: 20 lines in 6 files changed: 6 ins; 5 del; 9 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7517.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7517/head:pull/7517

PR: https://git.openjdk.java.net/jdk/pull/7517