RFR: 8305783: x86_64: Optimize AbsI and AbsL

Sun Apr 9 09:48:49 UTC 2023

Hi,

This patch optimizes the sequence emitted by `AbsINode` and `AbsLNode` to save some instructions and 1 temp register. Please take a look and kindly leave your reviews.

Thanks a lot.

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Commit messages:
 - more efficient abs implementations

Changes: https://git.openjdk.org/jdk/pull/13402/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13402&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8305783
  Stats: 28 lines in 1 file changed: 0 ins; 10 del; 18 mod
  Patch: https://git.openjdk.org/jdk/pull/13402.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13402/head:pull/13402

PR: https://git.openjdk.org/jdk/pull/13402