RFR: 8352065: [PPC64] C2: Implement PopCountVL, CountLeadingZerosV and CountTrailingZerosV nodes

[Martin Doerr]

On Fri, 14 Mar 2025 16:09:34 GMT, David Linus Briemann <duke at openjdk.org> wrote:

> VectorCastL2X was not added due to bad performance and thus the bit count instructions are only vectorized for `int` but not for `long`.

I've reviewed the new instructions and the usage in the .ad file. Looks all correct. Changing `TestNumberOfContinuousZeros.java` to test vectorization with `int` types on Power9 and later makes sense.
I only wonder about `TestPopCountVectorLong.java`. We're enabling the test which is supposed to test vectorization for `long`, but we run it without vectorization on PPC64? Wouldn't it be better to keep the test disabled for PPC64 (revert changes in this file)?

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PR Review: https://git.openjdk.org/jdk/pull/24064#pullrequestreview-2705400116