[jdk8u-dev] RFR: 8283441: C2: segmentation fault in ciMethodBlocks::make_block_at(int)

[Jiří Vaněk]

backport of https://github.com/openjdk/jdk/commit/947869609ce6b74d4d28f79724b823d8781adbed

Build and test passes, now running full jtregs

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Commit messages:
 - JDK-8283441 - C2: segmentation fault in ciMethodBlocks::make_block_at(int)

Changes: https://git.openjdk.org/jdk8u-dev/pull/376/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=376&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8283441
  Stats: 106 lines in 5 files changed: 94 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/376.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/376/head:pull/376

PR: https://git.openjdk.org/jdk8u-dev/pull/376