RFR: 8372451: C2 SuperWord: "endless loop" assert. Need to implement proper worklist mechanism [v2]

[Emanuel Peter]

> **Context**: `VTransform::optimize`. Works a bit like IGVN, it allows each node to perform optimizations. Recently introduced during JDK26.
> 
> **Problem**: I made the assumption that we don't need a worklist mechanism, we can just do multiple passes over all nodes. The assumption was that there would not be any "trickling" of updates over the graph. But that is wrong: for example we can have a long chain of dead nodes, and we need to progressively remove the last node and mark it as dead.
> 
> **Solution**: Implement proper worklist mechanism, so that updates can trickle over the graph.

Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision:

  limit steps of optimize, for Manuel

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Changes:
  - all: https://git.openjdk.org/jdk/pull/28512/files
  - new: https://git.openjdk.org/jdk/pull/28512/files/f5219b12..9f5bf837

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=28512&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=28512&range=00-01

  Stats: 5 lines in 1 file changed: 5 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/28512.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28512/head:pull/28512

PR: https://git.openjdk.org/jdk/pull/28512