Avoid creating a redundant zero APInt.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52602 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp
index e13011f..38b3790 100644
--- a/lib/Support/APInt.cpp
+++ b/lib/Support/APInt.cpp
@@ -2048,7 +2048,7 @@
     result = "-";
     insert_at = 1;
   }
-  if (tmp == APInt(tmp.getBitWidth(), 0))
+  if (tmp == zero)
     result = "0";
   else while (tmp.ne(zero)) {
     APInt APdigit(1,0);