[jdk21u-dev] RFR: 8337660: C2: basic blocks with only BoxLock nodes are wrongly treated as empty [v2]

[Goetz Lindenmaier]

> I backport this for parity with 21.0.7-oracle
> 
> I had to adapt the flags in the run command of the test, 
> as the locking mode is experimental in 21:
> 
> Error: VM option 'LockingMode' is experimental and must be enabled via -XX:+UnlockExperimentalVMOptions.
> Error: The unlock option must precede 'LockingMode'.
> Error: Could not create the Java Virtual Machine.
> Error: A fatal exception has occurred. Program will exit.

Goetz Lindenmaier has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR. The pull request contains one new commit since the last revision:

  Backport 0105203575182e24a56a38a12da7c1af58ea0a78

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Changes:
  - all: https://git.openjdk.org/jdk21u-dev/pull/1293/files
  - new: https://git.openjdk.org/jdk21u-dev/pull/1293/files/795036dc..f3a1011e

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1293&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1293&range=00-01

  Stats: 87 lines in 1 file changed: 87 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1293.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1293/head:pull/1293

PR: https://git.openjdk.org/jdk21u-dev/pull/1293