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

[Nikita Popov via llvm-commits]

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@@ -95,6 +95,17 @@ KnownBits ConstantRange::toKnownBits() const {
   return Known;
 }
 
+std::pair<ConstantRange, ConstantRange> ConstantRange::splitPosNeg() const {
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nikic wrote:

Should add unit test for the new API.

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