RFR: 8310126: C1: Missing receiver null check in Reference::get intrinsic

[Tobias Hartmann]

We crash in C1 compiled code due a missing null check on the argument of the `Reference::get` method. The problem is that after [JDK-8201543](https://bugs.openjdk.org/browse/JDK-8201543), see [here](https://hg.openjdk.org/jdk/jdk/rev/4bb58f644e4e#l43.46), no `CodeEmitInfo` is passed to `access_load_at` and therefore no implicit null check is emitted.

Thanks,
Tobias

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Commit messages:
 - 8310126: C1: Missing receiver null check in Reference::get intrinsic

Changes: https://git.openjdk.org/jdk/pull/14511/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14511&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310126
  Stats: 63 lines in 2 files changed: 62 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14511.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14511/head:pull/14511

PR: https://git.openjdk.org/jdk/pull/14511