RFR: 8373697: AArch64: Remove deoptimization stub code for nmethods with small stack frames

[Andrew Haley]

On Thu, 18 Dec 2025 11:34:42 GMT, Ruben <duke at openjdk.org> wrote:

> If we are to remove deoptimization stub code, we need an alternative way for the VM to identify the nmethod based on the return address value.
> At the same time, the return address value should be a valid pointer to executable code transferring control to the shared deoptimization blob.

Surely we don't need any of this complication. When we patch the CodeBlob frame's return address with the PC of the deopt handler, we could also store nmethod* into the slot for r8 in the same CodeBlob frame. When that CodeBlob returns, the nmethod* is in r8, and the deopt handler can read it there.

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PR Comment: https://git.openjdk.org/jdk/pull/28857#issuecomment-3677947326