[llvm] [NFC][LV] Introduce enums for uncountable exit detail and style (PR #184808)

[Sander de Smalen via llvm-commits]

================
@@ -245,6 +245,13 @@ struct HistogramInfo {
       : Load(Load), Update(Update), Store(Store) {}
 };
 
+/// Indicates the characteristics of a loop with an uncountable early exit.
+/// * None      -- No uncountable exit present.
+/// * ReadOnly  -- At least one uncountable exit in a readonly loop.
+/// * ReadWrite -- At least one uncountable exit in a loop with side effects
+///                that may require masking.
+enum class UncountableEarlyExitDetail { None, ReadOnly, ReadWrite };
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sdesmalen-arm wrote:

nit: I find 'Detail' a bit odd, perhaps rename to:
```suggestion
enum class UncountableEarlyExitTrait { None, ReadOnly, ReadWrite };
```
?

https://github.com/llvm/llvm-project/pull/184808