[jdk11u-dev] RFR: 8265132: C2 compilation fails with assert "missing precedence edge"

[Martin Doerr]

Almost clean backport of JDK-8265132. Only a small hunk in block.hpp had to get inserted manually due to an unrelated context difference. Test fails in 11u without the fix.

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Commit messages:
 - Backport 5644c4f942d9280ecc2dd3fdcd1680db6621da27

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/124/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=124&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265132
  Stats: 57 lines in 3 files changed: 36 ins; 16 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/124.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/124/head:pull/124

PR: https://git.openjdk.java.net/jdk11u-dev/pull/124