[jdk17u-dev] RFR: 8318183: C2: VM may crash after hitting node limit [v2]

[Aleksey Shipilev]

> Semi-clean backport to solve a potential VM crash due to C2 failing.
> 
> The uncleanliness comes from two places:
> 
>  1. In `Compile::Optimize()`, we do not have the new hunk from [JDK-8286104](https://bugs.openjdk.org/browse/JDK-8286104):  https://github.com/openjdk/jdk/commit/31e50f2c7642b046dc9ea1de8ec245dcbc4e1926#diff-f076857d7da81f56709da3de1511b1105727032186cde4d02c678667761f46eaR2247-R2248 -- so no return is needed.
>  2. In `PhaseIdealLoop::verify`, we do not have the rewrites from [JDK-8173709](https://bugs.openjdk.org/browse/JDK-8173709): https://github.com/openjdk/jdk/commit/24c6af0637631153707615932f1f10ced4e5c0e8#diff-d49652d43244d52415873c37bf6990269b0d6e2f2111f4f971660470b6bca738R4653-R4657 -- so I had to resolve the conflict by hand.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug `tier{1,2,3}`
>  - [x] Linux AArch64 server fastdebug `tier{1,2,3}`

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 two additional commits since the last revision:

 - Merge branch 'master' into JDK-8318183-c2-crash-node-limit
 - Backport 31ef400f31b1fd9a861870cce69f6d3eec72aa46

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

Changes:
  - all: https://git.openjdk.org/jdk17u-dev/pull/2044/files
  - new: https://git.openjdk.org/jdk17u-dev/pull/2044/files/612848ed..dc645cd4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2044&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2044&range=00-01

  Stats: 10262 lines in 202 files changed: 5884 ins; 2239 del; 2139 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2044.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2044/head:pull/2044

PR: https://git.openjdk.org/jdk17u-dev/pull/2044