RFR: 8348659: AArch64: IR rule failure with compiler/loopopts/superword/TestSplitPacks.java

[Bhavana Kilambi]

"test5a" in this file fails on Graviton3 (32B, SVE) as the compiler fails to match IR rules for vector size 2. This is because the minimum vector size for aarch64 machines is 8B and it does not support generation of vectors of 2 short values.

Modified the IR rules to have two separate rules - one for sse4.1 and another for sve.

The test now passes on Graviton3.

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Commit messages:
 - 8348659: AArch64: IR rule failure with compiler/loopopts/superword/TestSplitPacks.java

Changes: https://git.openjdk.org/jdk/pull/23385/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23385&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348659
  Stats: 13 lines in 1 file changed: 10 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/23385.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23385/head:pull/23385

PR: https://git.openjdk.org/jdk/pull/23385