RFR: 8339205: Optimize StackMapGenerator [v5]

[Shaojin Wen]

> Reduce code size by combining calls and defining local variables

Shaojin Wen has updated the pull request incrementally with one additional commit since the last revision:

  Update src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
  
  Co-authored-by: Chen Liang <liach at openjdk.org>

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Changes:
  - all: https://git.openjdk.org/jdk/pull/20756/files
  - new: https://git.openjdk.org/jdk/pull/20756/files/59102d50..eca48ba0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20756&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20756&range=03-04

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20756.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20756/head:pull/20756

PR: https://git.openjdk.org/jdk/pull/20756