RFR: 8341141: Optimize DirectCodeBuilder [v18]

[Shaojin Wen]

> Some DirectCodeBuilder related optimizations to improve startup and running performance:
> 1. Merge calls, merge writeU1 and writeU2 into writeU3
> 2. Merge calls, merge writeU1 and writeIndex operations
> 3. Directly use writeU1 instead of writeBytecode
> 4. Rewrite the implementation of load and store

Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 77 commits:

 - Merge branch 'master' into optim_direct_code_builder_202409
 - optimize DirectClassBuilder::build
 - writeU2U2U2
 - optimization for powerOctal
 - label write clean
 - optimizer for codeSize
 - optimize MethodTypeDescImpl::descriptorString
 - Remove redundant requireNonNull
 - optimize buildContent
 - optimize setLabelTarget
 - ... and 67 more: https://git.openjdk.org/jdk/compare/39c17b39...6dfa07ed

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Changes: https://git.openjdk.org/jdk/pull/21243/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21243&range=17
  Stats: 967 lines in 16 files changed: 585 ins; 119 del; 263 mod
  Patch: https://git.openjdk.org/jdk/pull/21243.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21243/head:pull/21243

PR: https://git.openjdk.org/jdk/pull/21243