RFR: 8284848: C2: Compiler blackhole arguments should be treated as globally escaping [v3]

[Aleksey Shipilev]

> Blackholes should make the arguments to be treated as globally escaping, to match the expected behavior of legacy JMH blackholes. See more discussion in the bug.
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug `tier1`
>  - [x] Linux x86_64 fastdebug `tier2`
>  - [x] OpenJDK microbenchmark corpus sanity run

Aleksey Shipilev 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 five additional commits since the last revision:

 - Merge branch 'master' into JDK-8284848-blackhole-ea-args
 - Fix failures found by microbenchmark corpus run 1
 - IR tests
 - Handle only pointer arguments
 - Fix

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8228/files
  - new: https://git.openjdk.java.net/jdk/pull/8228/files/3e0a2c28..cb8085f8

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8228&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8228&range=01-02

  Stats: 6494 lines in 76 files changed: 6164 ins; 128 del; 202 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8228.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8228/head:pull/8228

PR: https://git.openjdk.java.net/jdk/pull/8228