[lworld] RFR: 8303000: [lworld] C2 compilation fails with assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr)) failed: correct memory chain

[Tobias Hartmann]

Mainline fix for [JDK-8288204](https://bugs.openjdk.org/browse/JDK-8288204) needs to be extended to account for flat/null-free arrays.

Best regards,
Tobias

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Commit messages:
 - 8303000: [lworld] C2 compilation fails with assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr)) failed: correct memory chain

Changes: https://git.openjdk.org/valhalla/pull/841/files
 Webrev: https://webrevs.openjdk.org/?repo=valhalla&pr=841&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303000
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/valhalla/pull/841.diff
  Fetch: git fetch https://git.openjdk.org/valhalla.git pull/841/head:pull/841

PR: https://git.openjdk.org/valhalla/pull/841