RFR: 8255606: Enable concurrent stack processing on x86_32 platforms [v3]

[Zhengyu Gu]

> 8255606: Enable concurrent stack processing on x86_32 platforms

Zhengyu Gu has updated the pull request incrementally with one additional commit since the last revision:

  Reverted back to cmpq/cmpl

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/945/files
  - new: https://git.openjdk.java.net/jdk/pull/945/files/c946b816..d6a88224

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=945&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=945&range=01-02

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/945.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/945/head:pull/945

PR: https://git.openjdk.java.net/jdk/pull/945