[lworld] RFR: 8250511: [lworld] C2 compilation crashes in PhaseIdealLoop::spinup

[Roland Westrelin]

In PhaseIdealLoop::flatten_array_element_type_check(), when pushing:

(LoadKlass (AddP (CastPP ...

through a Phi, the control of CastPP clone is set to region->in(i) but
the AddP clone control is set to get_ctrl(phi->in(i)) which can be
above region->in(i) while the AddP is below the CastPP. Fix is to use
region->in(i) for all clones.

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Commit messages:
 - fix control used when pushing LoadKlass thru phi in PhaseIdealLoop::flatten_array_element_type_check()

Changes: https://git.openjdk.java.net/valhalla/pull/157/files
 Webrev: https://webrevs.openjdk.java.net/valhalla/157/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8250511
  Stats: 3 lines in 1 file changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/157.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/157/head:pull/157

PR: https://git.openjdk.java.net/valhalla/pull/157