[jdk17u] RFR: 8268882: C2: assert(n->outcnt() != 0 || C->top() == n || n->is_Proj()) failed: No dead instructions after post-alloc

[Martin Doerr]

Clean backport of JDK-8268882.

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Commit messages:
 - Backport 0699220830a457959b784b35af125b70f43fa3b0

Changes: https://git.openjdk.java.net/jdk17u/pull/264/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=264&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268882
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/264.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/264/head:pull/264

PR: https://git.openjdk.java.net/jdk17u/pull/264