RFR: 8282204: Use lea instructions for arithmetic operations on x86_64 [v5]

[Jie Fu]

On Mon, 28 Feb 2022 11:55:32 GMT, Quan Anh Mai <duke at openjdk.java.net> wrote:

> Icelakes introduce `clwb` instruction so I use that to filter Intel cpus.

I'm not sure if we can find a better way (e.g., cpuid) to filter Intel CPUs.
However, this seems fine since gcc and llvm will generate `lea` even without `clwb`.

> Mostly for completeness only, do you think I should revert this? Thank you very much.

Yes.
I would suggest not touching unnecessary part of code.

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PR: https://git.openjdk.java.net/jdk/pull/7560