Add a comment about debug intrinsics that I *really* don't want to

forget from Duncan's review as a FIXME.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163892 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/SROA.cpp

@@ -615,6 +615,8 @@ private:
   }
 
   // Disable SRoA for any intrinsics except for lifetime invariants.
+  // FIXME: What about debug instrinsics? This matches old behavior, but
+  // doesn't make sense.
   bool visitIntrinsicInst(IntrinsicInst &II) {
     if (II.getIntrinsicID() == Intrinsic::lifetime_start ||
         II.getIntrinsicID() == Intrinsic::lifetime_end) {