[llvm] [LoopVectorize] Vectorize select-cmp reduction pattern for increasing integer induction variable (PR #67812)

[Graham Hunter via llvm-commits]

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@@ -900,6 +993,11 @@ bool RecurrenceDescriptor::isReductionPHI(PHINode *Phi, Loop *TheLoop,
                       << *Phi << "\n");
     return true;
   }
+  if (AddReductionVar(Phi, RecurKind::IFindLastIV, TheLoop, FMF, RedDes, DB, AC,
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huntergr-arm wrote:

The AnyOf recurrence kinds do the same thing, although there is a separate check for `FAnyOf` below which wouldn't be reached if `IAnyOf` matched it first, and is just redundant work if there wasn't a match.

We would only see that when looking at iv-descriptors debug output, and there's no tests for that. This code at least reports the correct type for an fcmp.

I figure it's fine with just the single case here.

https://github.com/llvm/llvm-project/pull/67812