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

Xiaohong Gong xgong at openjdk.java.net
Thu Jul 8 10:50:53 UTC 2021


On Thu, 8 Jul 2021 10:45:36 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> Yes, but you reverse the bits in $dst, which reverses the byte order and changes each 0x01 byte to 0x80. You then count the leading zeroes. What, then, is the point of negating each 0x01 byte to 0xff first?
>
> Yes, I was intending to make the bits right after reversing. But seems it's also ok to remove the `negr` for `firsttrue`. And for `lasttrue`, I think it's better to keep the `negr`. I will remove it for `firsttrue` and have a test. Thanks for the review!

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

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


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