Use clear() to zero an existing APInt.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52601 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index bca5e75..abd7272 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1406,7 +1406,7 @@
   case ISD::CTPOP: {
     unsigned LowBits = Log2_32(BitWidth)+1;
     KnownZero = APInt::getHighBitsSet(BitWidth, BitWidth - LowBits);
-    KnownOne  = APInt(BitWidth, 0);
+    KnownOne.clear();
     return;
   }
   case ISD::LOAD: {