RFR: JDK-8294902: Undefined Behavior in C2 regalloc with null references [v3]

[Vladimir Kozlov]

On Wed, 23 Nov 2022 10:54:27 GMT, Andrew Haley <aph at openjdk.org> wrote:

>>> > Changes are good. Can you tell more about `-fsanitize=null` effect on libjvm size and performance of fastdebug build we use in testing? If it is only few percents I am for enabling it in debug build.
>>> 
>>> It might be a bit more than that: it's a test-and-branch on every memory access. Maybe enable it only on a non-optimized build?
>> 
>> I am fine with enabling it for debug VM. But can you give at least some numbers?
>
>> > > Changes are good. Can you tell more about `-fsanitize=null` effect on libjvm size and performance of fastdebug build we use in testing? If it is only few percents I am for enabling it in debug build.
>> > 
>> > 
>> > It might be a bit more than that: it's a test-and-branch on every memory access. Maybe enable it only on a non-optimized build?
>> 
>> I am fine with enabling it for debug VM. But can you give at least some numbers?
> 
> Sorry I'm being slow on this. I'm trying to get scoped values done before the fork.

@theRealAph you may defer it to next release (`tbd`) since you don't have time to work on this.

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