RFR: 8370853: IGV: SEGV in IdealGraphPrinter::print after JDK-8370569

[Roberto Castañeda Lozano]

On Wed, 29 Oct 2025 09:29:52 GMT, Roberto Castañeda Lozano <rcastanedalo at openjdk.org> wrote:

>> This (trivial?) changeset initializes `IdealGraphPrinter::_parse` to `nullptr` on construction. This prevents segmentation faults when this field is accessed in: https://github.com/openjdk/jdk/blob/20bcf0eddaee0a57142bcc614cc5415b53c16460/src/hotspot/share/opto/idealGraphPrinter.cpp#L1007-L1017
>> This failure is triggered when IGV graph dumping is run with a print level lower than 6 on platforms where `IdealGraphPrinter::_parse` is not implicitly initialized to `nullptr`. On print level 6, `IdealGraphPrinter::_parse` is initialized by https://github.com/openjdk/jdk/blob/5a2b0ca7fea7d1a283aa90696c3989ae189148ec/src/hotspot/share/opto/parse2.cpp#L2785 before it is accessed.
>> 
>> **Testing:** tier1-3 (including the affected test `TestVectorInsertByte.java` on the affected platform `macosx-aarch64-debug`).
>
> This failure illustrates the need for basic regression tests that exercise IGV graph dumping. I reported an RFE for adding them: [JDK-8370870](https://bugs.openjdk.org/browse/JDK-8370870).

> LGTM. Thanks for fixing it @robcasloz

Thanks for reviewing, Damon!

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PR Comment: https://git.openjdk.org/jdk/pull/28040#issuecomment-3460567084