RFR: 8269725: AArch64: Add VectorMask query implementation for NEON [v2]

[Ningsheng Jian]

On Thu, 8 Jul 2021 10:47:36 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

> Seems `negr` is also needless for `lasttrue`, since `7 >> 3 == 0` ?

Yeah. And the in-reg mask representation of these VectorMaskOp nodes (0/1) are different from anytrue/alltrue (VectorTest, 0/-1), which looks a bit confusing.

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PR: https://git.openjdk.java.net/jdk/pull/4699