yet more code review comments

Author: alanzhao1

llvm/include/llvm/IR/PassTimingInfo.h

@@ -81,8 +81,6 @@ class TimePassesHandler {
   TimePassesHandler();
   TimePassesHandler(bool Enabled, bool PerRun = false);
 
-  ~TimePassesHandler() = default;
-
   /// Prints out timing information and then resets the timers.
   void print();
 

llvm/lib/IR/PassTimingInfo.cpp

@@ -62,14 +62,10 @@ class PassTimingInfo {
 
 private:
   StringMap<unsigned> PassIDCountMap; ///< Map that counts instances of passes
-  DenseMap<PassInstanceID, Timer *> TimingData; ///< timers for pass instances
+  DenseMap<PassInstanceID, std::unique_ptr<Timer>> TimingData; ///< timers for pass instances
   TimerGroup *PassTG = nullptr;
 
 public:
-  PassTimingInfo() = default;
-
-  ~PassTimingInfo() = default;
-
   /// Initializes the static \p TheTimeInfo member to a non-null value when
   /// -time-passes is enabled. Leaves it null otherwise.
   ///
@@ -127,16 +123,16 @@ Timer *PassTimingInfo::getPassTimer(Pass *P, PassInstanceID Pass) {
 
   init();
   sys::SmartScopedLock<true> Lock(*TimingInfoMutex);
-  Timer *&T = TimingData[Pass];
+  std::unique_ptr<Timer> &T = TimingData[Pass];
 
   if (!T) {
     StringRef PassName = P->getPassName();
     StringRef PassArgument;
     if (const PassInfo *PI = Pass::lookupPassInfo(P->getPassID()))
       PassArgument = PI->getPassArgument();
-    T = newPassTimer(PassArgument.empty() ? PassName : PassArgument, PassName);
+    T.reset(newPassTimer(PassArgument.empty() ? PassName : PassArgument, PassName));
   }
-  return T;
+  return T.get();
 }
 
 PassTimingInfo *PassTimingInfo::TheTimeInfo;