[jdk11u-dev] RFR: 8303511: C2: assert(get_ctrl(n) == cle_out) during unrolling

[Goetz Lindenmaier]

I backport this for parity with 11.0.20-oracle.

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Commit messages:
 - Backport 04eb720d03edc37d7e1cb32c909c31c40485d7a8

Changes: https://git.openjdk.org/jdk11u-dev/pull/1973/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1973&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303511
  Stats: 84 lines in 2 files changed: 82 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1973.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/1973/head:pull/1973

PR: https://git.openjdk.org/jdk11u-dev/pull/1973