RFR: 8345273: Fix -Wzero-as-null-pointer-constant warnings in s390 code [v2]

[Andrew Haley]

On Fri, 6 Dec 2024 06:33:01 GMT, Kim Barrett <kbarrett at openjdk.org> wrote:

>> Please review this change to remove -Wzero-as-null-pointer-constant warnings
>> in s390 code.
>> 
>> Most places involve just changing literal 0 to nullptr.
>> 
>> Removed a dead return after ShouldNotReachHere() that is no longer needed.
>> 
>> Testing:
>> GHA sanity test build, with and without -Wzero-as-null-pointer-constant enabled.
>> I don't have the capability to run tests for this platform, so hoping someone
>> from the aix-ppc maintainers can do more testing.
>
> Kim Barrett has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
> 
>  - Merge branch 'master' into fix-s390-zero-null
>  - simple s390 fixes

Marked as reviewed by aph (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/22469#pullrequestreview-2492394768