[lworld] RFR: 8244092: [lworld] TestC2CCalls segfaults in frame::sender_for_compiled_frame with ZGC

[Tobias Hartmann]

Stack slot containing real_frame_size is trashed by ZCG barrier code in scalarized entry of C1 compiled code. As a
result, we crash during stack walking. We should re-set it before jumping to the verified entry. Also refactored the
related code and added an assert to catch this.

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Commit messages:
 - 8244092: [lworld] TestC2CCalls segfaults in frame::sender_for_compiled_frame with ZGC

Changes: https://git.openjdk.java.net/valhalla/pull/31/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/31/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8244092
  Stats: 73 lines in 3 files changed: 28 ins; 40 del; 5 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/31.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/31/head:pull/31

PR: https://git.openjdk.java.net/valhalla/pull/31