[vectorIntrinsics] RFR: 8255437: [vector] jdk/incubator/vector/SelectFromByteMaxVectorTests f…

[Xiaohong Gong]

…ails with Arm SVE 2048-bits

The tests are used to test the Vector API "selectFrom". It uses index values stored in the lanes of this vector which is a byte vector for byte type. So its valid lane elements should be 0 ~ 127 for byte.

However, for SVE 2048-bits, the max vector length for byte is 256, which exceeds the byte boundary. Indexes greater than 127 are converted to the negative values which are invalid for the API.

To avoid this, it's better to guarantee the elements in the byte vector to the valid values if they are prepared to be used as vector indexes.

See more details from:
https://mail.openjdk.java.net/pipermail/panama-dev/2020-October/011216.html

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Commit messages:
 - 8255437: [vector] jdk/incubator/vector/SelectFromByteMaxVectorTests fails with Arm SVE 2048-bits

Changes: https://git.openjdk.java.net/panama-vector/pull/19/files
 Webrev: https://webrevs.openjdk.java.net/?repo=panama-vector&pr=19&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8255437
  Stats: 15 lines in 3 files changed: 14 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/panama-vector/pull/19.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-vector pull/19/head:pull/19

PR: https://git.openjdk.java.net/panama-vector/pull/19