[counters] Making counter properly reentrant.

src/counters.h

Index: src/counters.h
diff --git a/src/counters.h b/src/counters.h
index bf10a4ece0b298aa680a335b0064dffb5135ff44..533e26ea1212bacd30920011ee2d7de7ed1ae6b7 100644
--- a/src/counters.h
+++ b/src/counters.h
@@ -701,27 +701,60 @@ double AggregatedMemoryHistogram<Histogram>::Aggregate(double current_ms,
   /* Total count of functions compiled using the baseline compiler. */         \
   SC(total_baseline_compile_count, V8.TotalBaselineCompileCount)
 
-typedef struct RuntimeCallCounter {
+struct RuntimeCallCounter {
+  explicit RuntimeCallCounter(const char* name) : name(name) {}
+  void Reset();
+
+  const char* name;
   int64_t count = 0;
   base::TimeDelta time;
-  RuntimeCallCounter* parent_counter;
+};
 
-  void Reset();
-} RuntimeCallCounter;
+// TimerLink is used to keep track of the stack of currently active timers used
+// for RuntimeCallCounter.
+class TimerLink {
+ public:
+  TimerLink(RuntimeCallCounter* counter, TimerLink* parent)
+      : counter_(counter), parent_(parent) {}
+
+  inline void Start() {
+    timer_.Start();
+    counter_->count++;
+  }
+
+  inline TimerLink* Stop() {
+    base::TimeDelta delta = timer_.Elapsed();
+    counter_->time += delta;
+    if (parent_ != NULL) {
+      parent_->AdjustForSubTimer(delta);
+    }
+    return parent_;
+  }
+
+  void AdjustForSubTimer(base::TimeDelta delta) { counter_->time -= delta; }
+
+ private:
+  RuntimeCallCounter* counter_;
+  TimerLink* parent_;
+  base::ElapsedTimer timer_;
+};
 
 struct RuntimeCallStats {
+  // Dummy counter for the unexpected stub miss.
+  RuntimeCallCounter UnexpectedStubMiss = {"UnexpectedStubMiss"};
+  // Counter for runtime callbacks into JavaScript.
+  RuntimeCallCounter RuntimeCallbacks = {"RuntimeCallback"};
 #define CALL_RUNTIME_COUNTER(name, nargs, ressize) \
-  RuntimeCallCounter Runtime_##name;
+  RuntimeCallCounter Runtime_##name = {#name};
   FOR_EACH_INTRINSIC(CALL_RUNTIME_COUNTER)
 #undef CALL_RUNTIME_COUNTER
-#define CALL_BUILTIN_COUNTER(name, type) RuntimeCallCounter Builtin_##name;
+#define CALL_BUILTIN_COUNTER(name, type) \
+  RuntimeCallCounter Builtin_##name = {#name};
   BUILTIN_LIST_C(CALL_BUILTIN_COUNTER)
 #undef CALL_BUILTIN_COUNTER
 
-  // Dummy counter for the unexpected stub miss.
-  RuntimeCallCounter UnexpectedStubMiss;
   // Counter to track recursive time events.
-  RuntimeCallCounter* current_counter;
+  TimerLink* current_timer_link_;
 
   // Starting measuring the time for a function. This will establish the
   // connection to the parent counter for properly calculating the own times.
@@ -729,7 +762,7 @@ struct RuntimeCallStats {
   // Leave a scope for a measured runtime function. This will properly add
   // the time delta to the current_counter and subtract the delta from its
   // parent.
-  void Leave(base::TimeDelta time);
+  void Leave();
 
   void Reset();
   void Print(std::ostream& os);