Add tests for max/minIntN(64).

Summary:
Given that we had a bug on max/minUIntN(64), these should have tests
too.

Reviewers: rnk

Subscribers: dylanmckay, llvm-commits

Differential Revision: https://reviews.llvm.org/D22443

llvm-svn: 275723
diff --git a/llvm/unittests/Support/MathExtrasTest.cpp b/llvm/unittests/Support/MathExtrasTest.cpp
index 3d449cc..d373030 100644
--- a/llvm/unittests/Support/MathExtrasTest.cpp
+++ b/llvm/unittests/Support/MathExtrasTest.cpp
@@ -121,11 +121,15 @@
 TEST(MathExtras, maxIntN) {
   EXPECT_EQ(32767, maxIntN(16));
   EXPECT_EQ(2147483647, maxIntN(32));
+  EXPECT_EQ(std::numeric_limits<int32_t>::max(), maxIntN(32));
+  EXPECT_EQ(std::numeric_limits<int64_t>::max(), maxIntN(64));
 }
 
 TEST(MathExtras, minIntN) {
   EXPECT_EQ(-32768LL, minIntN(16));
   EXPECT_EQ(-64LL, minIntN(7));
+  EXPECT_EQ(std::numeric_limits<int32_t>::min(), minIntN(32));
+  EXPECT_EQ(std::numeric_limits<int64_t>::min(), minIntN(64));
 }
 
 TEST(MathExtras, maxUIntN) {