RFR: 8291555: Replace stack-locking with fast-locking [v4]

[Roman Kennke]

On Thu, 13 Oct 2022 08:46:45 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

> On aarch64 (linux and mac) I see these variations of crashes in random tests: (asserts in debug, crash in release it looks like)
> 
> ```
> #  Internal Error .... src/hotspot/share/c1/c1_Runtime1.cpp:768), pid=2884803, tid=2884996
> #  assert(oopDesc::is_oop(oop(obj))) failed: must be NULL or an object: 0x000000000000dead
> # V  [libjvm.so+0x7851d4]  Runtime1::monitorexit(JavaThread*, oopDesc*)+0x110
> ```
> 
> ```
> #  SIGSEGV (0xb) at pc=0x0000fffc9d4e3de8, pid=1842880, tid=1842994
> # V  [libjvm.so+0xbf3de8]  SharedRuntime::monitor_exit_helper(oopDesc*, JavaThread*)+0x24
> ```
> 
> ```
> #  SIGSEGV (0xb) at pc=0x0000fffca9f00394, pid=959883, tid=959927
> # V  [libjvm.so+0xc90394]  ObjectSynchronizer::exit(oopDesc*, JavaThread*)+0x54
> ```

Ugh. That is most likely caused by the recent change:
https://github.com/rkennke/jdk/commit/ebbcb615a788998596f403b47b72cf133cb9de46

It used to be very stable before that. I have backed out that change, can you try again?

Thanks,
Roman

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

PR: https://git.openjdk.org/jdk/pull/10590