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

[Jakub Kuderski via llvm-commits]

================
@@ -3094,3 +3094,35 @@ void llvm::LoadIntFromMemory(APInt &IntVal, const uint8_t *Src,
     memcpy(Dst + sizeof(uint64_t) - LoadBytes, Src, LoadBytes);
   }
 }
+
+APInt APIntOps::avgFloorS(const APInt &C1, const APInt &C2) {
+  // Return floor((C1 + C2) /2))
+  unsigned FullWidth = C1.getBitWidth() + 1;
+  APInt C1Ext = C1.sext(FullWidth);
+  APInt C2Ext = C2.sext(FullWidth);
+  return (C1Ext + C2Ext).extractBits(C1.getBitWidth(), 1);
+}
+
+APInt APIntOps::avgFloorU(const APInt &C1, const APInt &C2) {
+  // Return floor((C1 + C2) /2))
+  unsigned FullWidth = C1.getBitWidth() + 1;
+  APInt C1Ext = C1.zext(FullWidth);
+  APInt C2Ext = C2.zext(FullWidth);
+  return (C1Ext + C2Ext).extractBits(C1.getBitWidth(), 1);
+}
+
+APInt APIntOps::avgCeilS(const APInt &C1, const APInt &C2) {
+  // Return ceil((C1 + C2) /2))
+  unsigned FullWidth = C1.getBitWidth() + 1;
+  APInt C1Ext = C1.sext(FullWidth);
+  APInt C2Ext = C2.sext(FullWidth);
+  return (C1Ext + C2Ext + 1).extractBits(C1.getBitWidth(), 1);
+}
+
+APInt APIntOps::avgCeilU(const APInt &C1, const APInt &C2) {
+  // Return ceil((C1 + C2) /2))
+  unsigned FullWidth = C1.getBitWidth() + 1;
+  APInt C1Ext = C1.zext(FullWidth);
+  APInt C2Ext = C2.zext(FullWidth);
+  return (C1Ext + C2Ext + 1).extractBits(C1.getBitWidth(), 1);
+}
----------------
kuhar wrote:

nit: missing newline

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