[llvm] [VPlan] Try to hoist Previous (and operands), if sinking fails for FORs. (PR #108945)

[via llvm-commits]

================
@@ -795,7 +881,8 @@ bool VPlanTransforms::adjustFixedOrderRecurrences(VPlan &Plan,
     }
 
     if (!sinkRecurrenceUsersAfterPrevious(FOR, Previous, VPDT))
-      return false;
+      if (!hoistPreviousBeforeFORUsers(FOR, Previous, VPDT))
----------------
ayalz wrote:

```suggestion
      if (!sinkRecurrenceUsersAfterPrevious(FOR, Previous, VPDT) &&
          !hoistPreviousBeforeFORUsers(FOR, Previous, VPDT))
```

https://github.com/llvm/llvm-project/pull/108945