RFR: 8331264: Reduce java.lang.constant initialization overhead

Mon Apr 29 08:15:27 UTC 2024

I'm looking at ways at reducing/eliminating startup overheads the classfile API in preparation of #17108, and have pushed a series of enhancements to that effect already. This PR is a collection of minor improvements which add up to a 1.5% reduction in retired instructions - or a 5% reduction in executed bytecode - on a simple lambda startup test.

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Commit messages:
 - Missed null-check on changeReturnType
 - Reduce java.lang.constant initialization overhead

Changes: https://git.openjdk.org/jdk/pull/18991/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18991&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8331264
  Stats: 72 lines in 6 files changed: 7 ins; 5 del; 60 mod
  Patch: https://git.openjdk.org/jdk/pull/18991.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18991/head:pull/18991

PR: https://git.openjdk.org/jdk/pull/18991