[jdk17] RFR: 8268369: SIGSEGV in PhaseCFG::implicit_null_check due to missing null check

[Tobias Hartmann]

I've missed a null check with [JDK-8266480](https://bugs.openjdk.java.net/browse/JDK-8266480), `ctrl` can be `NULL` (the comment above even says so).

Thanks,
Tobias

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Commit messages:
 - 8268369: SIGSEGV in PhaseCFG::implicit_null_check due to missing null check

Changes: https://git.openjdk.java.net/jdk17/pull/212/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=212&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268369
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/212.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/212/head:pull/212

PR: https://git.openjdk.java.net/jdk17/pull/212