RFR: JDK-8294902: Undefined Behavior in C2 regalloc with null references [v5]

[Vladimir Ivanov]

On Thu, 1 Dec 2022 17:22:12 GMT, Andrew Haley <aph at openjdk.org> wrote:

>> I'm sorry, I've been looking at this for a while, and I can't figure out what "move the assert under the null check" means. There are three asserts here, and two of them are under the `if (caller_jvms != NULL)` check.
>
>> Please, initialize `_caller_jvms` to `NULL` (on line 47), switch the null check to `caller_jvms` (on line 60), a
> 
> Done.

I'm talking specifically about the assert you are adjusting:

assert(_caller_jvms->same_calls_as(caller_jvms), "consistent JVMS");

It can be left as is once it is under `caller_jvms != NULL`, since there's no need in `_caller_jvms == NULL` anymore.

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PR: https://git.openjdk.org/jdk/pull/10920