[block-freq] Add a right shift to BlockFrequency that saturates at 1.

llvm-svn: 197302
diff --git a/llvm/unittests/Support/BlockFrequencyTest.cpp b/llvm/unittests/Support/BlockFrequencyTest.cpp
index ffdea2c..c318451 100644
--- a/llvm/unittests/Support/BlockFrequencyTest.cpp
+++ b/llvm/unittests/Support/BlockFrequencyTest.cpp
@@ -237,4 +237,12 @@
   EXPECT_FALSE(BigZero >= BigOne);
 }
 
+TEST(BlockFrequencyTest, SaturatingRightShift) {
+  BlockFrequency Freq(0x10080ULL);
+  Freq >>= 2;
+  EXPECT_EQ(Freq.getFrequency(), 0x4020ULL);
+  Freq >>= 20;
+  EXPECT_EQ(Freq.getFrequency(), 0x1ULL);
+}
+
 }