RFR: 8274401: C2: GraphKit::load_array_element bypasses Access API

[Martin Doerr]

C2: GraphKit::load_array_element only creates nodes for loading a raw element from the given array. This is wrong when the element is an Oop which needs a load barrier for some GCs.

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Commit messages:
 - 8274401: C2: GraphKit::load_array_element bypasses Access API

Changes: https://git.openjdk.java.net/jdk/pull/5727/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5727&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8274401
  Stats: 7 lines in 4 files changed: 1 ins; 0 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5727.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5727/head:pull/5727

PR: https://git.openjdk.java.net/jdk/pull/5727