RFR: 8371628: C2: add a test case for the arraycopy changes in JDK-8297933

[Daniel Skantz]

On Wed, 12 Nov 2025 15:58:00 GMT, Daniel Skantz <dskantz at openjdk.org> wrote:

> This PR adds a test for the arraycopy bug that caused a crash in `ArrayCopyNode::prepare_array_copy` and was fixed in JDK-8297933. A crash with this signature was previously reported on `compiler/c1/TestArrayCopy.java` but this test does not reproduce the issue (at least not reliably).
> 
> Testing: T1-3. Extra testing: the added test reliably fails if the arraycopy changes from JDK-8297933 are backed out.

Thanks for reviewing!

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PR Comment: https://git.openjdk.org/jdk/pull/28269#issuecomment-3531220668