[llvm] ConstRange: factor and introduce splitPosNeg (NFC) (PR #126528)

[Nikita Popov via llvm-commits]

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@@ -92,6 +92,9 @@ class [[nodiscard]] ConstantRange {
   /// unsigned domain.
   static ConstantRange fromKnownBits(const KnownBits &Known, bool IsSigned);
 
+  /// Split the ConstantRange into positive and negative components.
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nikic wrote:

I think this could explicitly mention that zero values will be ignored.

https://github.com/llvm/llvm-project/pull/126528