RFR: 8343789: Move mutable nmethod data out of CodeCache [v14]

[Dean Long]

On Tue, 29 Apr 2025 10:30:24 GMT, Doug Simon <dnsimon at openjdk.org> wrote:

>> The cast was added by 8331087, which reduced the supported JVMCI data size to uint16_t.  I don't remember this issue with long names coming up during that review, so I guess we all missed it.  @dougxc please file a bug so we can track this.  It seems like JVMCINMethodData::copy should do something like truncate long names rather than blindly assuming it has enough space.  If uint16_t is unreasonably small for JVMCI nmethod data we could revert that change and make it 32 bits again.
>
> I think in 8331087, I think only `_jvmci_data_offset` was subject to the [narrowing cast](https://github.com/openjdk/jdk/pull/18984/files#diff-c345a29edc19eb49f833e007143e00f897bb762b0f451a202e1d2f5304ed2308R1496).
> I've opened https://bugs.openjdk.org/browse/JDK-8355896.

Yes, my mistake.  I was thinking `_jvmci_data_offset` was used to compute `jvmci_data_end()`, not `jvmci_data_begin()`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21276#discussion_r2067417832