[BDCE] Add comments. NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305739 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/DemandedBits.cpp b/lib/Analysis/DemandedBits.cpp
index 8f808f3e78719b34bc157574ec05339d11ae7900..926b28d6094a5bff2945a8e751713e8fa3bb7a79 100644 (file)
--- a/lib/Analysis/DemandedBits.cpp
+++ b/lib/Analysis/DemandedBits.cpp
@@ -107,6 +107,8 @@ void DemandedBits::determineLiveOperandBits(
         AB = AOut.byteSwap();
         break;
       case Intrinsic::bitreverse:
+        // The alive bits of the input are the reversed alive bits of
+        // the output.
         AB = AOut.reverseBits();
         break;
       case Intrinsic::ctlz: