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

[Manuel Hässig]

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

Thank you for the thorough investigation and the fixes. Filing issues and concentrating on the case at hand sounds good to me. I have a few more comments on the test.

test/hotspot/jtreg/compiler/c2/TestUnlockNodeNullMemprof.java line 37:

> 35:     public static void main(String[] args) {
> 36:         int[] a = new int[0]; // test valid only when size is 0.
> 37:         for (int i = 0; i < Integer.valueOf(10000); i++)

Suggestion:

        for (int i = 0; i < Integer.valueOf(10000); i++) // test only valid with boxed loop limit

This surprised me, so I would appreciate the comment, but feel free to leave it.

test/hotspot/jtreg/compiler/c2/TestUnlockNodeNullMemprof.java line 39:

> 37:         for (int i = 0; i < Integer.valueOf(10000); i++)
> 38:             try {
> 39:                 test(a, 0);

Suggestion:

                test(a);

See below

test/hotspot/jtreg/compiler/c2/TestUnlockNodeNullMemprof.java line 44:

> 42:     }
> 43: 
> 44:     static void test(int[] a, int invar) {

Suggestion:

    static void test(int[] a) {

The test works without `invar`.

-------------

Changes requested by mhaessig (Committer).

PR Review: https://git.openjdk.org/jdk/pull/28432#pullrequestreview-3518247186
PR Review Comment: https://git.openjdk.org/jdk/pull/28432#discussion_r2571147027
PR Review Comment: https://git.openjdk.org/jdk/pull/28432#discussion_r2571140040
PR Review Comment: https://git.openjdk.org/jdk/pull/28432#discussion_r2571082704