8255531: MethodHandles::permuteArguments throws NPE when duplicating dropped arguments

[JornVernee]

Hi,

This small patch fixes the NPE in the following case:

MethodHandle mh = MethodHandles.empty(MethodType.methodType(void.class, int.class, int.class));
MethodHandles.permuteArguments(mh, MethodType.methodType(void.class, int.class), 0, 0);

If a parameter name was changed by a lambda form edit, LambdaForm::endEdit will try to sort the names that fall into the old range of parameter names (starting from firstChanged and up to arity in the code) to make sure that non-parameter names (exprs) properly appear after parameter names. But, if a parameter was dropped, and there are no non-paramter names, a null will fall into the range that is being sorted, and the call to name.isParam() in the sorting algorithm will result in an NPE.

We can just add a name != null check there, since null is definitely not a parameter. However, we still need to do the loop in order to get an accurate exprp value, which is later used to adjust the arity after sorting (there are other ways to get there that don't involve copying the extra null, but they are more convoluted, so I elected to go for this solution).

Thanks,
Jorn

Testing: tier1-tier2

---

Progress

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Issue

• JDK-8255531: MethodHandles::permuteArguments throws NPE when duplicating dropped arguments

Reviewers

• Claes Redestad (@cl4es - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/2054/head:pull/2054
$ git checkout pull/2054

[bridgekeeper]

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[openjdk]

@JornVernee The following labels will be automatically applied to this pull request:

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[JornVernee]

/label remove hotspot-compiler

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@JornVernee
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[mlbridge]

Webrevs

• 00: Full (c3611ce)

[cl4es]

LGTM.

[openjdk]

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

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8255531: MethodHandles::permuteArguments throws NPE when duplicating dropped arguments

Reviewed-by: redestad

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At the time when this comment was updated there had been 132 new commits pushed to the master branch:

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• 4f11ff3: 8259488: Shenandoah: Missing timing tracking for STW CLD root processing
• 0785147: 8259949: x86 32-bit build fails when -fcf-protection is passed in the compiler flags
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• 69f90b5: 8259843: initialize dli_fname array before calling dll_address_to_library_name
• 52ed2aa: 8259786: initialize last parameter of getpwuid_r
• 70b5b31: 8257664: HTMLEditorKit: Wrong CSS relative font sizes
• 0b01d69: 8260005: Shenandoah: Remove unused AlwaysTrueClosure in ShenandoahConcurrentRootScanner::roots_do()
• 0529480: 8259867: Move encoding checks into ZipCoder
• 7c32ffe: 8258383: vmTestbase/gc/g1/unloading/tests/unloading_compilation_level[1,2,3] time out without TieredCompilation
• ... and 122 more: https://git.openjdk.java.net/jdk/compare/c338f1167f2ab0c1a35876419db914dce844d5e8...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[JornVernee]

/integrate

[openjdk]

@JornVernee Since your change was applied there have been 256 commits pushed to the master branch:

• a68c6c2: 8260579: PPC64 and S390 builds failures after JDK-8260467
• 8752257: 8260502: [s390] NativeMovRegMem::verify() fails because it's too strict
• 8fe1323: 8260520: Avoid getting permissions in JarFileFactory when no SecurityManager installed
• ecde52e: 8260506: VersionHelper cleanup
• a97aedf: 8256215: Shenandoah: re-organize saving/restoring machine state in assembler code
• 316d52c: 8260497: Shenandoah: Improve SATB flushing
• 11a70d1: 8260426: awt debug_mem.c DMem_AllocateBlock might leak memory
• 396a496: 8260467: Move well-known classes from systemDictionary.hpp to vmClasses.hpp
• 62ffe75: Merge
• e28e111: 8260370: C2: LoopLimit node is not eliminated
• ... and 246 more: https://git.openjdk.java.net/jdk/compare/c338f1167f2ab0c1a35876419db914dce844d5e8...master

Your commit was automatically rebased without conflicts.

Pushed as commit d07af2b.

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