Fix APFloat::getLargest so that it actually returns the correct value.  Found by accident while reviewing a patch to nearby code.

llvm-svn: 141816
diff --git a/llvm/unittests/ADT/APFloatTest.cpp b/llvm/unittests/ADT/APFloatTest.cpp
index 3c40a13..e70c5f7 100644
--- a/llvm/unittests/ADT/APFloatTest.cpp
+++ b/llvm/unittests/ADT/APFloatTest.cpp
@@ -648,4 +648,9 @@
   EXPECT_FALSE(APFloat(1.40129846e-45f).getExactInverse(0));
 }
 
+TEST(APFloatTest, getLargest) {
+  EXPECT_EQ(3.40282347e+38f, APFloat::getLargest(APFloat::IEEEsingle).convertToFloat());
+  EXPECT_EQ(1.7976931348623157e+308, APFloat::getLargest(APFloat::IEEEdouble).convertToDouble());
+}
+
 }