RFR: 8347645: C2: XOR bounded value handling blocks constant folding [v11]

[Emanuel Peter]

On Tue, 28 Jan 2025 04:01:42 GMT, Johannes Graham <duke at openjdk.org> wrote:

>> C2 does not eliminate XOR nodes with constant arguments. This has a noticeable effect on `Long.expand` with a constant mask, on architectures that don't have instructions equivalent  to `PDEP` to be used in an intrinsic.
>> 
>> This patch demonstrates a potential fix to the problem, but there might well be better ways to do it.
>
> Johannes Graham has updated the pull request incrementally with one additional commit since the last revision:
> 
>   avoid MIN_VALUE in test

That is unfortunate indeed. It would be nice if we had some way of running the Types independently of the CompilerThread. It would really improve our ability to test Types.

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PR Comment: https://git.openjdk.org/jdk/pull/23089#issuecomment-2624005101