RFR: 8309902: C2: assert(false) failed: Bad graph detected in build_loop_late after JDK-8305189

[Roland Westrelin]

The crash happens after the following steps:

1- pre/main/post loops are created with assert predicates above the main loop.

2- the main loop is peeled

3- as a consequence, the `OpaqueZeroTripGuard` for the main loop is removed

4- That allows narrowing of the type of the CastII that was added right
  after the zero trip guard during pre/main/post loops creation
  
5- The CastII feeds into a range check CastII for the peeled iteration
  that becomes top because the narrowed type of the first CastII
  conflicts with the type recorded in the range check CastII.
  
6- The assert predicate that should fold to protect the range check
  CastII doesn't because of the fix for JDK-8282592: on assert
  predicate updates, the CastII at the zero trip guard is skipped. So
  the range check CastII sees the narrowing of the type of the CastII
  at the zero trip guard but the assert predicate doesn't.
  
The fix I propose is to revert that part of the change from
JDK-8282592 so both the range check CastII and the assert predicate
have the CastII at the zero trip guard as input and observe its type
updates. I went back to that bug and tried to reproduce the failure
again but couldn't. Reverting JDK-8281429 causes the bug to reproduce
again. I tried tweaking the test so the crash reproduces with
JDK-8281429 applied but couldn't.

This is caused by JDK-8305189 because step 3- happens because of
it. Before JDK-8305189, 3- happened after loop opts are over. I think
what happened then was that a template assertion predicate that was in
the process of having its `OpaqueLoopInit` and `OpaqueLoopStride`
removed constant folded so the crash wouldn't reproduce.

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Commit messages:
 - test & fix

Changes: https://git.openjdk.org/jdk/pull/14672/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14672&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309902
  Stats: 64 lines in 2 files changed: 58 ins; 6 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/14672.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14672/head:pull/14672

PR: https://git.openjdk.org/jdk/pull/14672