RFR: 8340454: C2 EA asserts with "previous reducible Phi is no longer reducible before SUT"

[Cesar Soares Lucas]

Please, consider this patch to fix an issue that happens when a Phi previously considered reducible become later irreducible. The overall situation that causes the problem is like so:

- Consider that there are at least 2 scalar replaceable objects (Obj1 and Obj2; Obj2 is stored in a field of Obj1) when we start iterating the loop at escape.cpp:301

- In the first iteration of the loop the call chain starting with `adjust_scalar_replaceable_state` ends up calling `can_reduce_phi` and considering Phi1 as reducible. This Phi has only Obj1 as *SR* input.

- In another iteration of the loop Obj2 is flagged as NSR. For instance, because we are storing Obj2 in an unknown position of an array. This will cause `found_nsr_alloc` to be set to `true`.

After the loop finishes, the execution will go to `find_scalar_replaceable_allocs`. The code will process Obj1, because it's still scalar replaceable, but will find that this object is stored in a field of a - **now** - NSR object. Therefore, correctly, Obj1 will also be marked as NSR. When Obj1 is marked as NSR Phi1 becomes irreducible because it doesn't have any more scalar replaceable input.

The solution I'm proposing is simply revisit the "reducibility" of the Phis when an object is marked as NSR.

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### Tests

Win, Mac & Linux tier1-4 on x64 & Aarch64.

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Commit messages:
 - fix spaces
 - Reevaluate Phi reducible status after one of its input become NSR.

Changes: https://git.openjdk.org/jdk/pull/21778/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21778&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340454
  Stats: 114 lines in 3 files changed: 111 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/21778.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21778/head:pull/21778

PR: https://git.openjdk.org/jdk/pull/21778