resolve comment

Author: mingmingl-llvm

llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp

@@ -168,12 +168,12 @@ static cl::list<std::string>
                       cl::desc("Prevent function(s) from being devirtualized"),
                       cl::Hidden, cl::CommaSeparated);
 
-/// If this value is other than 0, the devirt module pass will stop
-/// transformation once the total number of devirtualizations reach the cutoff
-/// value.
+/// If explicitly specified, the devirt module pass will stop transformation
+/// once the total number of devirtualizations reach the cutoff value. Setting
+/// this option to 0 explicitly will do 0 devirtualization.
 static cl::opt<unsigned> WholeProgramDevirtCutoff(
     "wholeprogramdevirt-cutoff",
-    cl::desc("Max number of devirtualization for devirt module pass"),
+    cl::desc("Max number of devirtualizations for devirt module pass"),
     cl::init(0));
 
 /// Mechanism to add runtime checking of devirtualization decisions, optionally
@@ -324,6 +324,9 @@ VirtualCallTarget::VirtualCallTarget(GlobalValue *Fn, const TypeMemberInfo *TM)
 
 namespace {
 
+// Tracks the number of devirted calls in the IR transformation.
+static unsigned NumDevirtCalls = 0;
+
 // A slot in a set of virtual tables. The TypeID identifies the set of virtual
 // tables, and the ByteOffset is the offset in bytes from the address point to
 // the virtual function pointer.
@@ -1177,14 +1180,16 @@ void DevirtModule::applySingleImplDevirt(VTableSlotInfo &SlotInfo,
       if (!OptimizedCalls.insert(&VCallSite.CB).second)
         continue;
 
+      // Stop when the number of devirted calls reaches the cutoff.
       if (WholeProgramDevirtCutoff.getNumOccurrences() > 0 &&
-          NumSingleImpl >= WholeProgramDevirtCutoff)
+          NumDevirtCalls >= WholeProgramDevirtCutoff)
         return;
 
       if (RemarksEnabled)
         VCallSite.emitRemark("single-impl",
                              TheFn->stripPointerCasts()->getName(), OREGetter);
       NumSingleImpl++;
+      NumDevirtCalls++;
       auto &CB = VCallSite.CB;
       assert(!CB.getCalledFunction() && "devirtualizing direct call?");
       IRBuilder<> Builder(&CB);