RFR: 8370502: C2: segfault while adding node to IGVN worklist [v4]

[Kerem Kat]

On Thu, 27 Nov 2025 19:14:05 GMT, Kerem Kat <krk at openjdk.org> wrote:

>> Do not try to replace `fallthrough_memproj` when it is null, fixes crash.
>> 
>> Test case is simplified from the ticket. Verified that the case crashes without the fix.
>
> Kerem Kat has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix rename

`gc/TestAllocHumongousFragment_generational` failed, seems unrelated:


#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x000055fe3a2ce64e, pid=7345, tid=7349
#
# JRE version: OpenJDK Runtime Environment (26.0) (build 26-internal-krk-a0f0ecb951a83c5069995130cfd803ad9165295f)
# Java VM: OpenJDK 64-Bit Server VM (26-internal-krk-a0f0ecb951a83c5069995130cfd803ad9165295f, mixed mode, static, sharing, tiered, compressed oops, compressed class ptrs, shenandoah gc, linux-amd64)
# Problematic frame:
# V  [java+0x149b64e]  void ShenandoahMark::mark_loop_work<ShenandoahMarkRefsClosure<(ShenandoahGenerationType)1>, (ShenandoahGenerationType)1, false, (StringDedupMode)0>(ShenandoahMarkRefsClosure<(ShenandoahGenerationType)1>*, unsigned short*, unsigned int, TaskTerminator*, StringDedup::Requests*) [clone .isra.0]+0x25e

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PR Comment: https://git.openjdk.org/jdk/pull/28432#issuecomment-3601288584