RFR: 8316880: AArch64: "stop: Header is not fast-locked" with -XX:-UseLSE since JDK-8315880 [v2]

[Andrew Haley]

On Mon, 2 Oct 2023 13:53:06 GMT, Nick Gasson <ngasson at openjdk.org> wrote:

>> Building a fastdebug image on a machine without LSE (e.g. A72) or explicitly disabling LSE results in:
>> 
>> 
>>   #
>>   # A fatal error has been detected by the Java Runtime Environment:
>>   #
>>   # Internal Error (0xe0000000), pid=64585, tid=64619
>>   # stop: Header is not fast-locked
>>   #
>>   # JRE version: OpenJDK Runtime Environment (22.0) (fastdebug build 22-internal-git-a2391a92c)
>>   # Java VM: OpenJDK 64-Bit Server VM (fastdebug 22-internal-git-a2391a92c, mixed mode, tiered, compressed oops, compressed class ptrs, g1 gc, linux-aarch64)
>>   # Problematic frame:
>>   # J 1373 c2 sun.nio.ch.NativeThreadSet.add()I java.base (155 bytes) @ 0x0000ffff7ccdf110 [0x0000ffff7ccdef80+0x0000000000000190]
>>   #
>> 
>> 
>> When UseLSE is false `MacroAssembler::cmpxchg()` uses rscratch1 as a temporary to store the result of the store-exclusive instruction. However rscratch1 may also be one of the registers passed as t1 or t2 to `MacroAssembler::lightweight_lock()` and holding a live value which is then clobbered.  Fixed by ensuring rscratch1 is never passed as one of these temporaries.
>
> Nick Gasson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Review suggestions

Marked as reviewed by aph (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/15978#pullrequestreview-1653162998