Make meanings of variables clearer in action table generation (NFC)

Summary:

Reviewers: kristina, zhmu, dschuff, rnk

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D52680

1 files changed, 12 insertions, 11 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
index 89fe3857228..be04b9a6e8c 100644
--- a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
@@ -99,7 +99,7 @@ void EHStreamer::computeActionsTable(
   FirstActions.reserve(LandingPads.size());
 
   int FirstAction = 0;
-  unsigned SizeActions = 0;
+  unsigned SizeActions = 0; // Total size of all action entries for a function
   const LandingPadInfo *PrevLPI = nullptr;
 
   for (SmallVectorImpl<const LandingPadInfo *>::const_iterator
@@ -107,23 +107,24 @@ void EHStreamer::computeActionsTable(
     const LandingPadInfo *LPI = *I;
     const std::vector<int> &TypeIds = LPI->TypeIds;
     unsigned NumShared = PrevLPI ? sharedTypeIDs(LPI, PrevLPI) : 0;
-    unsigned SizeSiteActions = 0;
+    unsigned SizeSiteActions = 0; // Total size of all entries for a landingpad
 
     if (NumShared < TypeIds.size()) {
-      unsigned SizeAction = 0;
+      // Size of one action entry (typeid + next action)
+      unsigned SizeActionEntry = 0;
       unsigned PrevAction = (unsigned)-1;
 
       if (NumShared) {
         unsigned SizePrevIds = PrevLPI->TypeIds.size();
         assert(Actions.size());
         PrevAction = Actions.size() - 1;
-        SizeAction = getSLEB128Size(Actions[PrevAction].NextAction) +
-                     getSLEB128Size(Actions[PrevAction].ValueForTypeID);
+        SizeActionEntry = getSLEB128Size(Actions[PrevAction].NextAction) +
+                          getSLEB128Size(Actions[PrevAction].ValueForTypeID);
 
         for (unsigned j = NumShared; j != SizePrevIds; ++j) {
           assert(PrevAction != (unsigned)-1 && "PrevAction is invalid!");
-          SizeAction -= getSLEB128Size(Actions[PrevAction].ValueForTypeID);
-          SizeAction += -Actions[PrevAction].NextAction;
+          SizeActionEntry -= getSLEB128Size(Actions[PrevAction].ValueForTypeID);
+          SizeActionEntry += -Actions[PrevAction].NextAction;
           PrevAction = Actions[PrevAction].Previous;
         }
       }
@@ -136,9 +137,9 @@ void EHStreamer::computeActionsTable(
             isFilterEHSelector(TypeID) ? FilterOffsets[-1 - TypeID] : TypeID;
         unsigned SizeTypeID = getSLEB128Size(ValueForTypeID);
 
-        int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
-        SizeAction = SizeTypeID + getSLEB128Size(NextAction);
-        SizeSiteActions += SizeAction;
+        int NextAction = SizeActionEntry ? -(SizeActionEntry + SizeTypeID) : 0;
+        SizeActionEntry = SizeTypeID + getSLEB128Size(NextAction);
+        SizeSiteActions += SizeActionEntry;
 
         ActionEntry Action = { ValueForTypeID, NextAction, PrevAction };
         Actions.push_back(Action);
@@ -146,7 +147,7 @@ void EHStreamer::computeActionsTable(
       }
 
       // Record the first action of the landing pad site.
-      FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
+      FirstAction = SizeActions + SizeSiteActions - SizeActionEntry + 1;
     } // else identical - re-use previous FirstAction
 
     // Information used when creating the call-site table. The action record