[Mlir-commits] [mlir] [MLIR] Introduce support for early exits (PR #166688)

[Matthias Springer]

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@@ -98,6 +98,10 @@ def SameOperandsAndResultElementType :
   NativeOpTrait<"SameOperandsAndResultElementType">;
 // Op is a terminator.
 def Terminator : NativeOpTrait<"IsTerminator">;
+// Op is a region terminator for the immediate region only.
+def ImmediateRegionTerminator : NativeOpTrait<"RegionTerminator", [Terminator]>;
+// Op is a region terminator, potentially breaking multiple regions
+def RegionTerminator : NativeOpTrait<"RegionTerminator", [Terminator]>;
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matthias-springer wrote:

Do we actually need `RegionTerminator` as a trait? An op is a region terminator if and only if `numBreakingControlRegions > 0`. (Is that actually the case?)

```c++
  /// Return the number of nested region levels this terminator exits.
  /// Returns 0 for ordinary operations that are not region terminators.
```

The verification seems to go only one way: you could have (registered) ops with `numBreakingControlRegions > 0` that do not implement the `RegionTerminator` trait. What would be the meaning of such an op?

https://github.com/llvm/llvm-project/pull/166688