[Tracing] Fix runtime call stats tracing for GC.

src/counters.h

Index: src/counters.h
diff --git a/src/counters.h b/src/counters.h
index 27ed8776ee665db93d0362529e569ac244ed25a1..18a35386f40f009ec81431be30a28304ebb39e72 100644
--- a/src/counters.h
+++ b/src/counters.h
@@ -810,15 +810,14 @@ class RuntimeCallStats {
 
 #define TRACE_RUNTIME_CALL_STATS(isolate, counter_name)                  \
   do {                                                                   \
-    if (FLAG_runtime_call_stats) {                                       \
-      RuntimeCallStats::CorrectCurrentCounterId(                         \
-          isolate->counters()->runtime_call_stats(),                     \
-          &RuntimeCallStats::counter_name);                              \
-    }                                                                    \
     if (V8_UNLIKELY(TRACE_EVENT_RUNTIME_CALL_STATS_TRACING_ENABLED())) { \
       RuntimeCallStats::CorrectCurrentCounterId(                         \
           isolate->counters()->tracing_runtime_call_stats(),             \
           &RuntimeCallStats::counter_name);                              \
+    } else if (FLAG_runtime_call_stats) {                                \
+      RuntimeCallStats::CorrectCurrentCounterId(                         \
+          isolate->counters()->runtime_call_stats(),                     \
+          &RuntimeCallStats::counter_name);                              \
     }                                                                    \
   } while (false)
 
@@ -1247,17 +1246,17 @@ class RuntimeCallTimerScope {
  public:
   inline RuntimeCallTimerScope(Isolate* isolate,
                                RuntimeCallStats::CounterId counter_id) {
-    if (V8_UNLIKELY(FLAG_runtime_call_stats)) {
+    if (V8_UNLIKELY(TRACE_EVENT_RUNTIME_CALL_STATS_TRACING_ENABLED())) {
+      isolate_ = isolate;
+      is_tracing_ = true;
+      RuntimeCallStats::Enter(
+          isolate_->counters()->tracing_runtime_call_stats(), &timer_,
+          counter_id);
+    } else if (V8_UNLIKELY(FLAG_runtime_call_stats)) {
       isolate_ = isolate;
       RuntimeCallStats::Enter(isolate_->counters()->runtime_call_stats(),
                               &timer_, counter_id);
     }
-    if (V8_UNLIKELY(TRACE_EVENT_RUNTIME_CALL_STATS_TRACING_ENABLED())) {
-      isolate_for_tracing_ = isolate;
-      RuntimeCallStats::Enter(
-          isolate_for_tracing_->counters()->tracing_runtime_call_stats(),
-          &trace_event_timer_, counter_id);
-    }
   }
   // This constructor is here just to avoid calling GetIsolate() when the
   // stats are disabled and the isolate is not directly available.
@@ -1265,26 +1264,21 @@ class RuntimeCallTimerScope {
                                RuntimeCallStats::CounterId counter_id);

[Camillo Bruni, 2016/09/07 02:00:29]

nit: could you declare both constructors in the same file.
secondary nit: could you use a delegating constructor for the HeapObject
version, this would save some code duplication.

[lpy, 2016/09/07 16:48:09]

Done.

 
   inline ~RuntimeCallTimerScope() {
-    if (V8_UNLIKELY(FLAG_runtime_call_stats)) {
-      RuntimeCallStats::Leave(isolate_->counters()->runtime_call_stats(),
-                              &timer_);
-    }
-    if (V8_UNLIKELY(isolate_for_tracing_ != nullptr)) {
-      RuntimeCallStats::Leave(
-          isolate_for_tracing_->counters()->tracing_runtime_call_stats(),
-          &trace_event_timer_);
-      isolate_for_tracing_ = nullptr;
+    if (V8_UNLIKELY(isolate_ != nullptr)) {
+      if (is_tracing_) {
+        RuntimeCallStats::Leave(
+            isolate_->counters()->tracing_runtime_call_stats(), &timer_);
+      } else {
+        RuntimeCallStats::Leave(isolate_->counters()->runtime_call_stats(),
+                                &timer_);
+      }
     }
   }
 
  private:
-  Isolate* isolate_;
-  // TODO(lpy): --runtime-call-stats and tracing should be mutually exclusive
-  // with tracing taking precendence. We need to add checks, and use a single
-  // isolate reference and a timer for both.
-  Isolate* isolate_for_tracing_ = nullptr;
+  Isolate* isolate_ = nullptr;
+  bool is_tracing_ = false;
   RuntimeCallTimer timer_;
-  RuntimeCallTimer trace_event_timer_;
 };
 
 }  // namespace internal