[lworld] RFR: 8252854: [lworld] Buffering in C1 entry can trigger safepoint before nmethod entry barrier has been executed

[Tobias Hartmann]

The runtime call to buffer scalarized inline type arguments in the C1 entry points can safepoint before the entry
barrier of the corresponding nmethod has been executed. As a result, oops in the nmethod might be bad and the GC
crashes in 'nmethod_oops_do'. We should simply execute the entry barrier before calling into the runtime.

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Commit messages:
 - 8252854: [lworld] Buffering in C1 entry can trigger safepoint before nmethod entry barrier has been executed

Changes: https://git.openjdk.java.net/valhalla/pull/180/files
 Webrev: https://webrevs.openjdk.java.net/?repo=valhalla&pr=180&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8252854
  Stats: 9 lines in 1 file changed: 7 ins; 2 del; 0 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/180.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/180/head:pull/180

PR: https://git.openjdk.java.net/valhalla/pull/180