[llvm] [ADT] Add implementations for avgFloor and avgCeil to APInt (PR #84431)

[Simon Pilgrim via llvm-commits]

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@@ -2193,6 +2193,18 @@ inline const APInt absdiff(const APInt &A, const APInt &B) {
   return A.uge(B) ? (A - B) : (B - A);
 }
 
+/// Compute the floor of the signed average of C1 and C2
+APInt avgFloorS(const APInt &C1, const APInt &C2);
+
+/// Compute the floor of the unsigned average of C1 and C2
+APInt avgFloorU(const APInt &C1, const APInt &C2);
+
+/// Compute the ceil of the signed average of C1 and C2
+APInt avgCeilS(const APInt &C1, const APInt &C2);
+
+/// Compute the ceil of the unsigned average of C1 and C2
+APInt avgCeilU(const APInt &C1, const APInt &C2);
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RKSimon wrote:

Does anyone have any preference for camelcase vs lowercase? 

https://github.com/llvm/llvm-project/pull/84431