RFR: JDK-8323497: On x64, use 32-bit immediate moves for narrow klass base if possible [v3]

[Thomas Stuefe]

On Wed, 21 Feb 2024 10:46:27 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> I don't think so. Why?
>
> I think the point is to reflow this into the series of ifs:
> 
> 
> char* result = nullptr;
> if (optimize_for_zero_base) {
>    result = ...
> }
> 
> if (result == nullptr) {
>    result = ...
> }
> 
> 
> Probably good for future maintenance if we want to add more cases in this block.

Ah okay. But that's wrong, since for the optimize_for_zero_base case, we would search the low address regions twice.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17340#discussion_r1497344358