RFR: 8291555: Implement alternative fast-locking scheme [v49]

[Roman Kennke]

On Fri, 31 Mar 2023 21:59:19 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

> v47 is hitting an assertion failure in my Mach5 Tier2 and Tier3 testing:
> 
> ```
> # Internal Error (/opt/mach5/mesos/work_dir/slaves/741e9afd-8c02-45c3-b2e2-9db1450d0832-S30407/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/b94a7623-5f98-46f3-8e2c-08444e95afa4/runs/a5754c45-3d7a-46fa-ba4b-c52efcf6ca3b/workspace/open/src/hotspot/share/runtime/lockStack.cpp:78), pid=1731612, tid=1731617
> # assert((_top < end_offset())) failed: lockstack overflow: _top 1704 end_offset 1704
> #
> # JRE version: Java(TM) SE Runtime Environment (21.0) (fastdebug build 21-internal-LTS-2023-03-31-1908037.daniel.daugherty.8291555forjdk21.git)
> # Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 21-internal-LTS-2023-03-31-1908037.daniel.daugherty.8291555forjdk21.git, mixed mode, tiered, compressed oops, compressed class ptrs, serial gc, linux-aarch64)
> # Problematic frame:
> # V [libjvm.so+0x10cfa0c] LockStack::verify_no_thread(char const*) const+0x288
> ```
> 
> Please see the bug for the latest details as I investigate.

Uh, that is a simple mistake. It should assert _top <= end_offset(). _top is allowed to be at _end, but not go beyond that.

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PR Comment: https://git.openjdk.org/jdk/pull/10907#issuecomment-1492868319