[jdk17u-dev] RFR: 8315920: C2: "control input must dominate current control" assert failure

[Goetz Lindenmaier]

I backport this for parity with 17.0.11-oracle.

I had to resolve two chunks in loopopt.cpp because of differences in context and spaces withing ().

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Commit messages:
 - Backport 4e1e579e8b916191397fc958df32ac3f6003c791

Changes: https://git.openjdk.org/jdk17u-dev/pull/2070/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=2070&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315920
  Stats: 97 lines in 4 files changed: 76 ins; 17 del; 4 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/2070.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/2070/head:pull/2070

PR: https://git.openjdk.org/jdk17u-dev/pull/2070