[Mlir-commits] [mlir] [MLIR][Utils] Fix overflow in constantTripCount for narrow types (PR #179985)

[Matthias Springer]

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@@ -397,11 +404,28 @@ std::optional<APInt> constantTripCount(
     return std::nullopt;
   }
 
+  // Extend stepCst to match the bitwidth of diff if needed (e.g., when diff was
+  // extended to avoid overflow). Step is always positive here, so zero-extend.
+  llvm::APInt extendedStepCst = stepCst;
+  if (extendedStepCst.getBitWidth() < diff.getBitWidth()) {
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matthias-springer wrote:

Bitwidth extension can also be dropped here.

https://github.com/llvm/llvm-project/pull/179985