8337523: Fix -Wzero-as-null-pointer-constant warnings in jvmci code

[kimbarrett]

Please review this trivial change that removes some uses of literal 0 as a
null pointer constant in jvmci code.

Testing: mach5 tier1

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8337523: Fix -Wzero-as-null-pointer-constant warnings in jvmci code (Enhancement - P4)

Reviewers

• Christian Hagedorn (@chhagedorn - Reviewer)
• Aleksey Shipilev (@shipilev - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/20399/head:pull/20399
$ git checkout pull/20399

Update a local copy of the PR:
$ git checkout pull/20399
$ git pull https://git.openjdk.org/jdk.git pull/20399/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 20399

View PR using the GUI difftool:
$ git pr show -t 20399

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/20399.diff

Webrev

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[bridgekeeper]

👋 Welcome back kbarrett! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@kimbarrett This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8337523: Fix -Wzero-as-null-pointer-constant warnings in jvmci code

Reviewed-by: chagedorn, shade

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At the time when this comment was updated there had been 1 new commit pushed to the master branch:

• de0b504: 8336912: G1: Undefined behavior for G1ConfidencePercent=0

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[openjdk]

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[mlbridge]

Webrevs

• 00: Full (b82603f9)

[chhagedorn]

Looks good and trivial.

[kimbarrett]

Thanks for reviews @chhagedorn and @shipilev

[kimbarrett]

/integrate

[openjdk]

Going to push as commit 61386c1.
Since your change was applied there have been 4 commits pushed to the master branch:

• 07dd725: 8337418: Fix -Wzero-as-null-pointer-constant warnings in prims code
• c73b3cb: 8336635: Add IR test for Reference.refersTo intrinsic
• 9b428dd: 8336242: compiler/jvmci/jdk.vm.ci.code.test/src/jdk/vm/ci/code/test/SimpleDebugInfoTest.java failed assert(oopDesc::is_oop_or_null(val)) failed: bad oop found (again)
• de0b504: 8336912: G1: Undefined behavior for G1ConfidencePercent=0

Your commit was automatically rebased without conflicts.

[openjdk]

@kimbarrett Pushed as commit 61386c1.

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