PR5207: Change APInt methods trunc(), sext(), zext(), sextOrTrunc() and
zextOrTrunc(), and APSInt methods extend(), extOrTrunc() and new method
trunc(), to be const and to return a new value instead of modifying the
object in place.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121120 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 64debfc..7962c3e 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1866,9 +1866,8 @@
 }
 
 static APInt ComputeRange(const APInt &First, const APInt &Last) {
-  APInt LastExt(Last), FirstExt(First);
   uint32_t BitWidth = std::max(Last.getBitWidth(), First.getBitWidth()) + 1;
-  LastExt.sext(BitWidth); FirstExt.sext(BitWidth);
+  APInt LastExt = Last.sext(BitWidth), FirstExt = First.sext(BitWidth);
   return (LastExt - FirstExt + 1ULL);
 }