[jdk17] RFR: 8262017: C2: assert(n != __null) failed: Bad immediate dominator info.

[Christian Hagedorn]

This was already reviewed:

https://github.com/openjdk/jdk/pull/4362

but needs to be fixed in 17.

Thanks,
Christian

-------------

Commit messages:
 - set_subtree_ctrl()
 - cleanup & signed_max/min
 - New fix
 - Revert fix
 - Add case for positive stride*scale
 - 8262017: C2: assert(n != __null) failed: Bad immediate dominator info.

Changes: https://git.openjdk.java.net/jdk17/pull/192/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=192&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8262017
  Stats: 192 lines in 2 files changed: 180 ins; 4 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/192.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/192/head:pull/192

PR: https://git.openjdk.java.net/jdk17/pull/192