[jdk11u-dev] RFR: 8248500: AArch64: Remove the r18 dependency on Windows AArch64

[Vladimir Kempik]

On Fri, 29 Oct 2021 15:51:58 GMT, Bernhard Urban-Forster <burban at openjdk.org> wrote:

> The ABI for AArch64 reserves r18 as a platform register [1]. Linux doesn't make use of it, thus it's available as an additional callee-saved register. This is not the case for Windows and macOS, therefore we have to make HotSpot aware of that.
> 
> [1] https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst#61machine-registers

We also have tested this patch(taken out of jep-388 backport to jdk11u) with zulu11 on macos-aarch64 about a month ago and found no regressions in linux/macos aarch64 builds

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PR: https://git.openjdk.java.net/jdk11u-dev/pull/567