Index: lib/CodeGen/AsmPrinter/EHStreamer.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/EHStreamer.cpp
+++ lib/CodeGen/AsmPrinter/EHStreamer.cpp
@@ -98,6 +98,11 @@
 
   FirstActions.reserve(LandingPads.size());
 
+  // SizeActions: size of all action entries for a function
+  // SizeSiteActions: size of all action entries for one landing pad
+  // SizeAction: size of an action entry (usually 2, size of typeid + size of
+  //             next action)
+  // SizeTypeID: size of typeid (usually 1)
   int FirstAction = 0;
   unsigned SizeActions = 0;
   const LandingPadInfo *PrevLPI = nullptr;