[jdk11u-dev] RFR: 8271202: C1: assert(false) failed: live_in set of first block must be empty

[Goetz Lindenmaier]

I backport this for parity with 11.0.15-oracle.

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Commit messages:
 - Backport 54b800d56d6bc86676722ad96e87b8344606bcb7

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/774/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=774&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271202
  Stats: 75 lines in 2 files changed: 75 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/774.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/774/head:pull/774

PR: https://git.openjdk.java.net/jdk11u-dev/pull/774