[jdk11u-dev] RFR: 8282555: Missing memory edge when spilling MoveF2I, MoveD2L etc

[Goetz Lindenmaier]

I backport this for parity with 11.0.17-oracle.

I had to replace nullptr by NULL, because hotspot does not compile C++11.

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Commit messages:
 - Backport 4a5e7a1ada611cfdefdc3b9a6fada05494e07390

Changes: https://git.openjdk.org/jdk11u-dev/pull/1185/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1185&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8282555
  Stats: 23 lines in 2 files changed: 23 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1185.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev pull/1185/head:pull/1185

PR: https://git.openjdk.org/jdk11u-dev/pull/1185