[llvm] [CodeGen] Optimize ctpop expansion using computeKnownBits (PR #221671)

[Matt Arsenault via llvm-commits]

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@@ -12246,6 +12244,19 @@ void SelectionDAGISel::LowerArguments(const Function &F) {
           OutVal = DAG.getNode(ISD::AssertNoFPClass, dl, OutVal.getValueType(),
                                OutVal, SDNoFPClass);
         }
+        if (VT.isInteger()) {
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arsenm wrote:

else if, and doesn't need the isInteger check

This also ought to be its own patch (I also thought range attributes already folded into AssertZext)

https://github.com/llvm/llvm-project/pull/221671