[jdk11u-dev] RFR: 8254827: JVMCI: Enable it for Windows+AArch64 [v3]

[Andrew Haley]

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

>> src/jdk.internal.vm.ci/share/classes/jdk.vm.ci.hotspot.aarch64/src/jdk/vm/ci/hotspot/aarch64/AArch64HotSpotRegisterConfig.java line 141:
>> 
>>> 139:     private static RegisterArray initAllocatable(Architecture arch, boolean reserveForHeapBase, boolean canUsePlatformRegister) {
>>> 140:         RegisterArray allRegisters = arch.getAvailableValueRegisters();
>>> 141:         Register[] registers = new Register[allRegisters.size() - reservedRegisters.size() - (reserveForHeapBase ? 1 : 0) - (!canUsePlatformRegister ? 1 : 0)];
>> 
>> This is confusing and complicated. If you set `platformRegister` to be either `r18` or `Register.None` depending on the OS, you don't need a separate boolean `canUsePlatformRegister`.
>
> I agree, it doesn't read nice. However the code around the definition of `platformRegister` doesn't know which platform we are dealing with. We could potentially pass down the `config` object via the constructor... or use the boolean flag as proposed here. Do you think it's worth changing it? I'm mostly worried about diverging from tip.

OK, I see. Let it stand.

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PR: https://git.openjdk.java.net/jdk11u-dev/pull/307